United States
Environmental Protection
Agency
<&EF¥V Research and
Development
TWO-PHASE FLOW OF TWO HFC
REFRIGERANT MIXTURES THROUGH
SHORT TUBE ORIFICES
EPA-600/R-95-168
November 1995
Prepared for
Office of Air and Radiation
Prepared by
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
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FOREWORD
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ATTENTION
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copy furnished NTIS by the
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Although it is recognized
that certain portions are
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TECHNICAL REPORT DATA
(Please read butfmftiotts en the reverse before comph III ||| 1 111 111 II H 1 III III
1. REPORT NO. 2.
EPA-600/R-95-168
a HI llll II Hill llllllllll t III 111
PB98-142045
4, TITLE ANO SUBTITLE
Two-phase Flow of Two HFC Refrigerant Mixtures
Through Short Tube Orifices
S. REPORT DATE
November 1995
6. PERFORMING ORGANIZATION COOE
7. AUTHOR®
W. Vance Payne and Dennis L. O'Neal
8. PERFORMING ORGANIZATION REPORT NO.
S. PERFORMING ORGANIZATION NAME ANO AOORESS
Texas A and M' University
Department of Mechanical Engineering
College Station, Texas 77843
10. PROGRAM ELEMENT NO.
11. CONTRACTA3RANT NO.
CR 822227
12. SPONSORING AGENCY NAME ANO AOORESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT ANO FEHIOO COVERED
Final; 1-12/94
14. SPONSORING AGENCY CODE
EPA/600/13
is.supplementary notes APPCD project officer is Robert V, Hendriks, Mail Drop 62B,
919/541-3928.
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EPA- 600 /R- 95-168
November 1995
TWO-PHASE FLOW OF TWO HFC REFRIGERANT
MIXTURES THROUGH SHORT TUBE ORIFICES
By:
W. Vance Payne
Dennis L. O'Neal
Energy Systems Laboratory
Department of Mechanical Engineering
Texas A&M University
College Station, TX 77843
EPA Cooperative Agreement No. CR-822227
EPA Project Officer:
Robert V. Hendriks
Air Pollution Prevention and Control Division
UJS. Environmental Protection Agency
Research Triangle Park, N.C. 27711
Prepared For:
U.S. Environmental Protection Agency
Office of Research and Development
Washington, D.C. 20460
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ABSTRACT
An experimental investigation was performed to develop an acceptable flow model for short
tube orifice expansion devices used in heat pumps. The refrigerants investigated were two
HFC mixtures considered HCFC-22 replacements: HFC-32/HFC-125/HFC-134a
(23%/25%/52% on a mass percentage basis) and HFC-32/HFC-125 (50%/50%). A series of
tests for both refrigerants was performed to generate data at varying operating conditions with
twelve short tubes. The tests included both single- and two-phase flow conditions at the inlet
of the short tube with different oil concentrations. Experimental data were presented as a
function of major operating parameters and short tube diameter. Based on test results and
analysis, a mass flow model was developed. The test results for both refrigerants showed the
mass flow rate was strongly dependent on upstream conditions, but slightly dependent on
downstream conditions. The mass flow rate was extremely sensitive to changes in short tube
diameter. The presence of oil below a concentration of approximately 2% would appear to
only slightly affect the mass flow rate (less than 5%). It was found that the semi-empirical
flow model estimates were in good agreement with laboratory results for both single- and
two-phase flow entering the short tubes.
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TABLE OF CONTENTS
CHAPTER Page
List of Tables * vi
List of Figures .v±ii
Nomenclature
I INTRODUCTION 1
n EXPERIMENTAL SETUP 3
Short Tube Description 6
Oil Injection and Sampling . 8
Instrumentation 10
Data Acquisition 12
H EXPERIMENTAL PROCEDURE... 14
IV EXPERIMENTAL RESULTS
FOR R32/125/134a (23%!25%152%) 20
Pure R32/125/134a (23%/25%/52%) 20
Mixture of Oil and R32/125/134a (23%/25%/52%) 28
Summary of Results for R32/125/134a (23%/25%/52%) 32
V EXPERIMENTAL RESULTS
FOR R32/125 (50%/50%) 34
Pure R32/125 (50%/50%) 34
Mixture of Oil and R32/125 (50%/50%) 42
Summary of Results for R32/125 (50%/50%) 47
VI SEMI-EMPIRICAL MODEL DEVELOPMENT 49
Goodness of Fit 59
iv
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CHAPTER CONTENTS (continued) Page
VII SUMMARY AND RECOMMENDATIONS 64
REFERENCES 68
APPENDIX A
MODEL COMPARISON WITH EXPERIMENTAL DATA 70
APPENDIX B
QUALITY ASSURANCE AND UNCERTAINTY ANALYSIS ... 81
Data Quality Objectives 88
Quality of Calculated Parameters 90
Inlet Quality,..,,... 90
Oil Concentration 92
Uncertainties Calculated ...'. 93
APPENDIX C
QUALITY ASSURANCE AUDIT REPORT.. 95
Technical Systems Audit 96
Audit of Data Quality.... 105
APPENDIX D
EXAMPLE THERMODYNAMIC STATE OF
THE TEST REFRIGERANTS...... 112
V
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LIST OF TABLES
Table Page
2.1 Dimensions of the Test Sections 8
2.2 Description of the Data Acquisition Sensor Channels 13
3.1 Sample of Operating Conditions 16
3.2 Summary of Gas Chromatograph Tests.. 17
5.1 Mass Flowrate Change for Two-Phase at Orifice Inlet. 37
5.2 Variation of Mass Flowrate with Orifice Diameter 39
5.3 Percent Change in Mass Flowrate for a
Change in Subcooling/Quality 48
6.1 Coefficients of Correction Factors in the Flow Model 54
6.2 - 95% Confidence Intervals for R32/125/134a 55
6.3 95% Confidence Intervals for R32/125 56
6.4 Limitations on the Application of the Flow Model 58
6.5 Overall Goodness of Fit for Mass Flow
Model Using 95% of the Data 59
6.6 Pure Single-Phase Model Comparison Based Upon Short Tube Length 60
6.7 Pure Single-Phase Model Comparison Based Upon Short Tube Diameters 60
6.8 Chi Squared Values for Semi-Empirical Models 63
7.1 Comparison of the Mass Flowrate for a Short
Tube with L=0.5 in (12.7 mm) and D=0.O528 in (1.34 mm) 65
B1 Test Matrix for Pure AC9000 with Orifice Length of 0.5 in (12,7 mm) 82
B2 Test Matrix for Pure AC9000 with Orifice Lengths
of 0.75 in (19.05 mm) and 1.00 in (25.4 mm) 83
B3 Test Matrix for Pure AZ20 with Orifices of Length of 0.5 in (12.7 mm) 84
VI
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TABLES (continued)
fable
B4 Test Matrix for Pure AZ20 with Orifices of Length ^a8e
0.75 in (19,05 mm) and 1.00 in (25.4 mm) 85
B5 Oil Tests for AC9000 86
B6 Oil Tests for AZ20 87
B7 Data Quality Summary for Directly Measured Variables 88
B8 Uncertainty of Quantities Used to Calculate Quality 92
B9 Example Quality Uncertainty Values 93
BIO Example Oil Concentration Uncertainty Values 94
D1 Thermodynamic Properties of the Saturated Liquid and Vapor Phases
for SUVA AC9000 Engineering Units 115
vii
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LIST OF FIGURES
Figure Page
2.1 Schematic diagram of the short tube test setup 4
2.2 Schematic of a short tube test section
for routine performance tests 7
2.3 Schematic of the sampling vessel and filter assembly 9
2.4 A typical refrigerant line temperature probe 11
4.1 Flow dependency on downstream pressure for a short tube
with length of 0.5 in (12.7 mm) and diameter of 0.0528 in (1.34 mm) 21
4.2 Flow dependency on subcooling/quality for three
upstream pressures for a short tube with length
0.5 in (12.7 mm) and diameter of 0.0528 in (1.34 mm) 23
4.3 Flow dependency on subcooling/quality for three
diameters and upstream pressures of 271 psia (1870 kPa)
at all downstream pressures.. . 23
4.4 Flow dependency on upstream pressure as a function of
upstream subcooling/quality for a short tube with length
0,5 in (12.7 mm) and diameter of0.0528 in (1.341 mm) 25
4.5 Flow dependency on short tube diameter for several upstream
pressures and subcoolings of 20°F (11.1°C) 26
4 .6 Mass flow as a function of diameter for upstream pressures of
271 psia (1870 kPa), length of 0.5 in (12.7 mm), and various
levels of subcooling/quality 26
4.7 Effects of length on mass flow for upstream pressure of
271 psia (1.9 MPa) and diameter of0.0528 in (1.341 mm) 27
4 8 Mass flow ratio as a function of oil concentration for upstream
pressure of 271 psia (1870 kPa), length of 0.5 in (12.7 mm),
diameter of 0.0528 in (1.34 mm), and several subcooling/qualities 29
4 .9 Mass flow ratio as a function of oil concentration for all upstream
pressures with length of 0.5 in (12.7 mm), diameter of0.0528 in
(1.34 mm), and subcooling of 10°F (5.6°C) 30
viii
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FIGURES (continued)
Figure
4.10 Mass flow ratio as a function of upstream subcooling Page
for several upstream pressures........ 31
4.11 Mass flow ratio as a function of upstream
pressures for all upstream subcoolings and 1% oil 32
5.1 Flow dependency on downstream pressure for a short tube of
length 0.5 in (12.7 mm) and diameter of0.052S in (1.341 mm)
with upstream pressure of 380 psia (2618 kPa). 35
5.2 Flow dependency on subeooling/quality for all upstream pressures
with length of 0.5 in (12.7 mm) and diameter of0.0528 in (1.341 mm) 36
5.3 Flow dependency on upstream pressure for all subcooling/qualities
and downstream pressures with length of 0.5 in (12.7 mm)
and diameter of0.0528 in (1.341 mm) 38
5 A Flow dependency on short tube diameter for all upstream pressures
at 20°F (11.1°C) subcooling and all downstream pressures..... 40
5.5 Effect of length on mass flowrate for a short tube of diameter
0.0528 in (1.341 mm), upstream pressure of380 psia (2618 kPa),
and several subcooling/qualities 41
5.6 Flow dependency on oil concentration for short tube with length of
0.5 in (12.7 mm), diameter of0.0528 in (1.341 mm), several
subcooling/qualities, and upstream pressure of380 psia (2618 kPa).. 43
5.7 Flow dependency on upstream subcooling at all upstream
pressures for the 0.0528 in (1.341 mm) diameter orifice 46
5.8 Flow dependency on upstream pressure for the short tube with
diameter of 0.0674 in (1.71 mm) and length of 0.5 in (12.7 mm)... 46
6.1 Control volume of the mass flow model 51
D1 Sample pressure-enthalpy diagram for a zeotropic refrigerant 113
D2 Sample pressure-enthalpy diagram for an azeotropic refrigerant 114
D3 Operating regime of the short tube orifice test bench 114
ix
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NOMENCLATURE
A, short tube cross-sectional area, in.2 (m2)
Cr oil concentration on a pure refrigerant basis
C, oil concentration based on oil and refrigerant mass
Cv correction factor for two-phase flow
D short tube diameter, in.(mm)
D^- reference short tube diameter, 0,060 in. (1.52 mm)
DR ratio of tube diameter to reference tube diameter, DlDre/-
EVAP normalized downstream pressure, (P in psia (kPa))
Yc dimensional gravity constant, SI unit: 1.2960 * 1010 [s2N/(h2 kN)]
English unit: 2.8953 x 106 [lbmft3/(lbf in2 h2)]
L short tube length, in. (mm)
UD ratio of short tube length to diameter
m ormr mass flow rate, Ibjh (kg/h)
mR mass flow ratio of oil and refrigerant mixtures to pure refrigerant
P . pressure, psia (kPa)
Pc critical pressure, psia (kPa)
Pjo^, downstream (evaporator) pressure, psia (kPa)
Pf adjusted downstream pressure, psia (kPa)
Pw, upstream liquid saturation pressure, psia (kPa)
Pup upstream (condenser) pressure, psia (kPa)
PRA ratio of upstream pressure to critical pressure, PUjJPc
Q heat transfer rate, Btu/h (W)
SUBC normalized subcooling, {T^T^T, [T in °R (K)]
T temperature, °R (K) or °F (°C)
Tc critical temperature, °R (K)
TMt liquid saturation temperature of the upstream fluid, °R (K)
Tup temperature of upstream fluid, °R (K)
x refrigerant quality
p density, lb^ft3 (kg/m3)
UA overall heat transfer coefficient, Btu/(h °R), (W/K)
X
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CHAPTER 1
INTRODUCTION
The need for new refrigerants was established when scientists first realized the ozone
depleting effects of CFC and HCFC refrigerants. The chlorine atom in these refrigerants is
capable of reaching the upper atmosphere where it can destroy more than 100,000 ozone
atoms (Langley 1994). Section 608 of the Clean Air Act (1990) prohibited the venting of
ozone depleting refrigerants as of July 1,1992. In addition, the Clean Air Act (1990) also
requires the EPA to develop regulations limiting the emissions of ozone depleting
refrigerants. Efforts are currently underway to find CFC replacements before the complete
phaseout of CFC manufacturing in January of 1996.
Much of the effort to replace CFC and HCFC refrigerants has centered on
development of refrigerant mixtures that could replace R-22. Before systems can be designed
with a new refrigerant (or mixture), thermodynamic and thermophysical properties must first
be characterized. An important component in air conditioners is the expansion device.
Because of their low cost, several manufacturers have chosen to use short tube orifices for the
expansion device in their systems. Designing a system with an orifice requires knowledge of
the flow characteristics of short tube orifices. Recent work on orifices has focused on R-12
and R-22 (Kim and O'Neal, 1993a; Aaron and Domanski, 1990; Krakow and Lin, 1988; and
Mei, 1982). In addition, there are unpublished data on R-134a (Kim and O'Neal, 1993b) and
the effect of lubricants on flow characteristics (Kim, 1993; Kim and O'Neal, 1994b).
The present study presents data for flow of two refrigerant mixtures through short
tube orifices. The two mixtures were R32/125/134a (23%/24%/52% on a mass percentage
1
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basis) and R32/125 (50%/50%). The following presents results for the flow of these two
refrigerants through short tube orifices of various diameters and lengths of 0,5 in (12.7 mm),
0.75 in (19 .05 mm), and 1.00 in (25,4 mm) in a pure form and mixed with various mass
percentages of oil.
2
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CHAPTER II
EXPERIMENTAL SETUP
A schematic diagram of the experimental setup is shown in Figure 2,1. The test loop
was designed to allow easy control of each operating parameter such as upstream subcooling
or quality, upstream pressure, and downstream pressure. It also allowed for changing the oil
concentration by injection of the oil into the system. The test rig consisted of three major
flow loops: (1) a refrigerant flow loop containing a detachable test section, (2) a hot water
flow loop used for the evaporation heat exchanger and (3) a chilled water-glycol flow loop
used for the condensation heat exchanger.
A diaphragm liquid pump with a variable speed motor was used to provide a wide
range of refrigerant mass flow rates. Ail advantage of the diaphragm pump was that it did not
require lubrication as would a compressor. Thus, it allowed oil concentration to be an
adjustable parameter in operating the system. The pressure entering the test section
(upstream or condenser pressure) was controlled by adjusting the speed of the refrigerant
pump. A hand-operated needle valve was utilized to permit precise control of upstream
pressure by bypassing liquid refrigerant from the pump to the short tube exit. To provide
additional flow control into the test section, a by-pass line which included a capillary tube was
utilized from the pump exit to the short tube exit. The refrigerant flow rate was measured by
a Coriolis effect mass flow meter in the liquid line between the pump and the evaporation heat
exchanger.
The refrigerant subcooling or quality entering the test section was set by a water
heated heat exchanger (evaporation heat exchanger) and a heat tape. For single-phase
3
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Liquid Pump
Oil Fill ft
Sampling
Liquid
Receiver
—©
Meter
Needle Valve
Cold
Water
Tank
i
Pump
x
-© .
-© T
Evaporation
Heat
Exchanger
Condensation
Heat
Exchanger
Ball Valve
J®
Filter
Sight Glass
Water
Tank
By-Pass
Valve
Ball Valve
Detachable _
Test Section /Heat Tape
Figure 2.1: Schematic Diagram of the Short Tube Test Setup.
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conditions at the inlet of the test section, most of the energy transfer to the refrigerant was
supplied by the evaporation heat exchanger. A heat tape with adjustable output from 0 to
3071 Btu/h (0.9 kW) was utilized to provide precise control of upstream subcooling. For
two-phase flow conditions at the inlet of the test section, the flow from the pump was heated
by the evaporation heat exchanger to 2°F (1.1°C) of subcooling, and a heat tape was used to
reheat the refrigerant to the desired inlet quality. A hot water loop supplying water to the
evaporation heat exchanger consisted of a residential water heater and a centrifugal pump.
Water flow rates were controlled by both a throttling valve and a by-pass valve. The
temperature of the water entering the heat exchanger was monitored using a thermocouple
and adjusted by a mechanical thermostat.
The heat tape was mounted along an eight foot (2 .44 m) section of refrigerant tubing
after the evaporation heat exchanger. To prevent heat loss to the ambient, the heat tape was
insulated with 9 in. (22.9 cm) thick rubber insulation. Six thermocouples were placed inside
and outside of the insulation to calculate the overall heat transfer coefficient for heat loss. For
two-phase entering the test section, the power input into the heat tape was measured using a
watt transducer. Liquid refrigerant temperature entering the heat tape section plus inside and
outside insulation temperatures were also measured. The refrigerant enthalpy at the inlet of
the test section was calculated by performing an energy balance of the power input into the
heat tape, heat loss through the insulation, and enthalpy at the inlet of the heat tape. The
enthalpy at the inlet of the heat tape, which was always subcooled, was determined from the
measured temperature and pressure. The quality of the refrigerant flow entering the test
section was calculated from the enthalpy and the measured pressure at the inlet of the test
section.
After all upstream conditions were established, the flow entered the test section. The
pressure and temperature were measured upstream and downstream of the short tube. .Flow
5
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conditions were also monitored using a sight glass at the exit of the short tube. A filter-dryer
was mounted in the by-pass line of the test section and was used prior to collection of data.
Two-phase refrigerant exiting the test section was condensed and subcooled in the
water/glycol cooled heat exchanger (condensation heat exchanger) so that the refrigerant
pump had only liquid at its suction side. A liquid receiver was used before the refrigerant
pump to ensure only liquid entered the pump. The pressure at the exit of the test section
(downstream or evaporator pressure) was controlled by adjusting the temperature and flow
rate of chilled water/glycol entering the heat exchanger. The water-glycol loop consisted of a
170 gal (644 L) insulated storage tank, 3 ton (10,6 kW) chiller unit, a centrifugal pump, and
a by-pass line concentric tube heat exchanger. The concentration of glycol in the water was
50 %. The water/glycol mixture was cooled to 3°F (-16°C) by the chiller. The mass flow rate
of the mixture was metered using a throttling valve and by-pass line. The temperature of the
storage tank and the supplied mixture to the heat exchanger were monitored by a
thermocouple.
SHORT TUBE DESCRIPTION
The orifice test section located between the heat tape and condensation heat
exchanger was designed to allow fast orifice replacement. The current testing utilized short
tube orifices having a length of 0.5 in. (12.7 mm), 0.75 in (19.05 mm), and 1.0 in (25,4 mm)
and no entrance chamfering. The orifice diameters were selected to correspond to
commercially available short tubes in residential air conditioners or heat pumps.
Figure 2.2 shows the schematic of the orifice test section for routine performance
tests. The short tube was made from brass which was bored and reamed to insure a smooth
surface. The short tubes were fixed between two 0.375 in. ± 0.005 in.(9.53 mm ± 0.13 mm)
f
O.D. * 8 in. ± 0.5 in. (20.32 cm ± 1.27 cm) long copper tubes using soft solder. The test
6
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section was mounted into the test loop using Swagelok connections which provided ease of
installation and replacement.
The short tubes used in this investigation are listed in Table 2.1. Short tube diameters
were measured using a precise plug gauge set with 0.0005 in. (0.013 mm) increment of
diameter. The precision error of the diameter measurement was estimated at ±0.0005 in.
(0.013 mm). Short tube lengths were measured with a dial caliper which had a ±0.0005 in.
(0,013 mm) accuracy.
Flow
Copper Tube
Soft Soldering
Short Tube
W$k
Short Tube Length (L)
Short Tube
.Diameter (D)
Figure 2.2: Schematic of a Short Tube Test Section for Routine Performance Tests.
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Table 2,1: Dimensions of the Test Sections
Refrigerant
Diameter, in.(mm)
Ternary:
0.0676(1.72)
@ 0.0763 (1.94)
OH. INJECTION and SAMPLING
The lubricant was injected into the suction side of the refrigerant pump using an air-
cylinder in a batch process. The testing sequence proceeded from pure refrigerant to oil and
refrigerant mixtures. Hie amount of the lubricant injected was calculated from the rod
displacement and the diameter of the cylinder. The weight of the lubricant batch was also
monitored to inject the required amount of oil using an electronic scale accurate to ±0.02 lb
(10.0 g).
Oil concentration was determined by sampling. The schematic of the sampling vessel
and filter assembly is shown in Figure 2.3. The sampling vessel was cylindrical and had an
inside diameter of 5 in. (12.7 cm) and a length of 12 in. (30.5 cm). The volume of sampling
vessel was large compared to the volume of the sample to ensure low vapor velocity during
the distilling procedure so that no oil particles could leave with the vapor. The amount of
refrigerant-lubricant mixture sampled from the suction side of the pump was approximately
one pound (0.454 kg). During the sampling process, the sample weight entering the vessel
was monitored using a scale accurate to ± 0.002 lb (± 1.0 g). After sampling, the refrigerant
i
8
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Sampling &
Vacuum Port
Filter
Sampling Vessel
»
iy|lillilll:|f
flU
¦laiis
liiiiiii
iillllililllS
:•¦¦
ivSv?;?;
Capillary
^Tube
Vapor Bleeding
Drain Port
Scale
Figure 2.3: Schematic of the Sampling Vessel and Filter Assembly.
was removed from the sampling vessel by slowly bleeding the refrigerant vapor through a
bleeder assembly which included a filter and a capillary tube 10 ft (3.05 m) long * 0.025 in,
(0.64 mm) bore to catch any entrained oil in the exiting refrigerant. After bleeding, the
cylinder was evacuated to remove any dissolved refrigerant in the lubricant. Based on the
measurement of the empty weight of the cylinder and filter assembly, the weight immediately
after sampling, and the weight after bleeding off the refrigerant, the oil concentration in the
refrigerant was calculated. The procedure for calculating the oil concentration was based on
ASHRAE Standard 41.4-1984 (ASHRAE 1984). According to this method, oil concentration
could be calculated by one of two methods. The first method, known as the sample basis
calculation, determined oil concentration based upon the mass of the oil and refrigerant. The
second method determined oil concentration based upon the pure refrigerant basis. Both
methods are described by the following equations:
9
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Method 1 ;
' mt-mt mr + ma
(21)
Method 2:
(2.2)
r m, - mf mr
where: mt = initial vessel weight
m0 = weight of the oil
m, = weight of the refrigerant
m( = total weight of vessel, refrigerant and oil
mj- = total weight of vessel and oil
All quantities reported in this report are based upon Method 2.
INSTRUMENTATION
Temperatures, pressures, flow rate, and power input were monitored in the test loop
using a computer and data acquisition system. Each sensor was calibrated before being
connected to the data logger to reduce experimental uncertainties.
All temperature measurements were made using copper constantan thermocouples.
The total error of the temperature measurement was estimated at ±0.72°F (0.4°C).
Calibration of a thermocouple was performed by adjusting a potentiometer located on each
isothermal block of the input card (the zero point was set using the ice bath). After making a
thermocouple junction, the thermocouple was calibrated in a constant temperature bath. Six
thermocouple probes were mounted in the refrigerant line to measure accurately the
refrigerant temperature. The probes with 1/16 in. (1.59 mm) O.D. were inserted far enough
into the flow of the refrigerant to minimize the conduction effects of the copper tube (Figure
Six pressure transducers were used in measuring the refrigerant pressures. Each
pressure transducer was calibrated with a standard dead weight tester . The pressure
2.4).
10
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transducers in the refrigerant line were installed with ball valves to allow easy disassembly
without any loss of the refrigerant in the system.
The refrigerant mass flow rate was measured with a Coriolis effect mass flow meter.
The precision of the flow meter was ±0.4% of full scale [26 lb/min (11.8 kg/min)]. Hot water
was used as a calibration liquid because hot water has approximately the same kinetic
viscosity as the refrigerants. Therefore, the error in the measurement of the mass flow rate
caused from the viscosity difference between refrigerants and a calibration liquid can be
assumed negligible (Tree 1970). Calibration was performed by measuring the weight of water
flowing into a measuring tank per unit time.
Thermocouple Wire
Shrinkable Tube
Flow
<5
Probe
Refrigerant Tube
Figure 2.4: A Typical Refrigerant Line Temperature Probe.
11
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A voltage transformer and a watt transducer were utilized to measure the power input
into the heat tape. A watt transducer was calibrated using a standard voltmeter and ampere
meter. Estimated experimental uncertainty was ±0.5% foil scale (5118 Btu/h (1.5 kW))
accuracy.
The two-phase quality at the inlet of the short tube was determined by applying an
energy balance to the heat tape at the entrance of the short tube. The uncertainty of the
quality was estimated using the Kline and McClintock (1953) error method. Based on sample
calculations, the uncertainties of the qualities were less than 4% of calculated qualities.
DATA ACQUISITION
The data acquisition was done with a personal computer and an Acurex (Model
Autocalc) data logger. Sensor signals from the test points listed in Table 2.2 were collected
and converted to engineering units by a data logger which handled millivolt and milliamp
signals as well as voltages and frequency signals. During the test, the data processed by the
data logger were transferred to a personal computer where they were displayed continuously
on the screen and stored on a hard disk. The scan rate was adjustable, so the data were
collected every six seconds. Before the final data were collected, all operating parameters
were monitored on the screen to check establishment of the required conditions.
After completion of the test for each short tube, the data reduction program, which
was written in QuickBASIC, was used to calculate properties for analysis. Thermodynamic
properties for the ternary zeotrope and binary near-azeotrope were calculated based upon
thermodynamic property data supplied by the refrigerant manufacturers.
12
-------
Table 2.2: Description of the Data Acquisition Sensor Channels.
Channel
Sensor Type
Location
00
Pressure Transducer
Shoit Tube Inlet
01
Pressure Transducer
Short Tube Exit
04
Pressure Transducer
Liquid Receiver Inlet
05
Pressure Transducer
Flow Meter Inlet
06
Pressure Transducer
Flow Meter Exit
07
Pressure Transducer
Upstream of Heat Tape
08
Flow Meter
Liquid Pump Exit
09
Watt Transducer
Heat Tape
10
Thermocouple-Probe
Short Tube Inlet
11 :
Thermocouple-Probe
Short Tube Exit
14
Thermocouple-Probe
Liquid Receiver Inlet
15
Thermocouple-Probe
Flow Meter Inlet
16
Thermocouple-Probe
Flow Meter Exit
17
Thermocouple-Probe
Upstream of Heat Tape
18-23
Thermocouple
Heat Tape Insulation
44
Mass Flow Meter
Liquid Pump Exit
13
-------
CHAPTER III
EXPERIMENTAL PROCEDURE
A series of experiments for each refrigerant was run to investigate the influence of the
operating parameters on the mass flow rate though the short tubes. Two types of experiments
were performed: (1) measurement of the mass flow for the pure refrigerants (i.e., no oil
added) and (2) measurements of the effects of oil concentration on performance. Conditions
were chosen to cover a wide range of operating conditions for a short tube expansion device
found in a typical residential heat pump or air-conditioner.
The experimental variables controlled included: (1) upstream subcooling or quality,
(2) upstream pressure, (3) downstream pressure, and (4) orifice geometry. Operating
pressures for the short tubes tested were selected based upon several condensing
temperatures. Nominal condensing temperatures 95°F (35.0°C), 110°F (43.3°C), and 125°F
(51.7°C) were selected for both the ternary and binary refrigerants. The corresponding
upstream saturation pressures for the ternary mixture were 221 psia (1524.kPa), 271 psia
(1870 kPa), and 329 psia (2271 kPa). The binary mixture had corresponding upstream
saturation pressures of 310 psia (2136kPa), 380 psia (2618 kPa), and 461 psia (3176 kPa).
Downstream pressures were selected based upon evaporating temperatures of 30°F (-1.1°C),
40°F (4.4°C), and 50°F (10.0°C) for both the ternary and binary refrigerants.
Upstream conditions were varied by altering the degree of subcooling of the
refrigerant for single phase tests and altering the quality for two-phase tests. Oil tests for the
binary and ternary mixtures were performed with oil concentrations on a mass basis ranging
from 0% to 2.15%. The lubricant was Mobil RL32S (32 centistokes) polyol ester.
Conditions for each test were a combination of operating variables listed in Table 3.1.
14
-------
Approximately 32 tests were completed for the pure refrigerants for each short tube diameter.
The downstream pressure for the oil tests were set at the median pressure used to test the
pure refrigerants. Oil tests were conducted for each orifice at all subcooling levels and
upstream pressures, but only the median downstream pressure was tested.
The data developed from the measurements included refrigerant flow rate, pressure
drop across the short tube, and upstream subcooling/quality. Data were taken at steady state.
Several criteria had to be met for the data to be accepted. The controlling parameters had to
be within the following limits: upstream pressure, ±1.0 psia (7 kPa); downstream pressure,
±2.0 psia (14 kPa); upstream temperature ±0.72°F (0.4°C); and quality, ±0.3%. When the
flow rate was insensitive to downstream pressure, the downstream pressure limit was set to
±5.0 psia (34 kPa) to allow faster stabilization of the flow conditions.
The setup was allowed to reach steady state while satisfying required operating
conditions before the final data acquisition was started. The establishment of steady state was
checked by monitoring the operating conditions and mass flow rates. When the system came
to steady-state, data were collected every six seconds for a period of four minutes. The data
for each channel were then averaged over four minute intervals.
15
-------
Table 3.1: Sample of Operating Conditions
Refrigerant
Upstream
Pressure, psia
(MPa)
Downstream
Pressure, psia
(MPa)
Subcooling or
Quality
Oil Mass
Percent
Ternary:
221
(1,53)
78
(0.54)
20°F
(11.1°C)
0%
R32/R125/R134a
271
(1.87)
94
(0.65)
10°F
(5.6°C)
1.0%
(23%/25%/52%)
329
(2.27)
111
(0.76)
5°F
(2.8°C)
0°F
(0°C)
5.0 %
Binary:
310
(2.14)
114
(0.78)
20°F
(ii. ro
0%
R32/R125
3S0
(2.62)
135
(0.93)
10°F
(5.6°C)
2.15%
(50%/50%)
461
(3.18)
160
(1.10)
5°F
(2.8°C)
0°F
(0°C)
5.0 %
ir
16
-------
After finishing a series of the tests for a short tube, the test section was replaced with
a new test section. The replacement of the test section was conducted by closing the ball
valves before and after the existing test section to shut off the refrigerant flow and opening
the bypass around the test section. After changing the test section, the space between the ball
valves was evacuated. Flow through the test section was re-established by opening the ball
valves and closing the bypass ball valves. The bypass line made it possible to re-route
refrigerant flow without shutting the system down, thus saving time in reaching steady state
with the new test section.
The composition of the ternary and binary refrigerant mixtures was checked by
performing a gas chromatograph (GC) analysis on small samples from the system taken during
testing. Samples were taken from the high pressure liquid side of the system. A summary of
the GC results is presented in Table 3.2. The zeotropic ternary mixture showed some
variation in composition between the liquid and vapor phases. Further sampling for the
ternary mixture confirmed the variation in composition seen in the summary data presented in
Table 3.2. The azeotropic binary mixture consistently yielded compositions as shown in the
table below.
Table 3.2: Summary of Gas Chromatograph Tests*
Refrigerant
Mass Percentages
Sample Source
R32/125/134a
(25.1 / 25.7/49.2)
Cylinder
(24.3/27.7/48.1)
System
R32/125
(51.4/48.6)
Cylinder
(53.1 /46.9)
• System
* Refrigerant composition tolerances were let «t ±4% for all tests.
17
-------
On completion of the tests with a refrigerant, the system was discharged and then
evacuated. The system was flushed with R-I34a and then evacuated again for several hours.
This flush/evacuate procedure was repeated for a total of two cycles. The system was then
charged with the required amount of the replacement refrigerant, which was around 15 lb (7
kg). After a series of test runs were made with the first short tube to verify charge levels, the
system was ready for further testing.
Oil was injected into the suction side of the pump (the detailed procedure was
described in the section "Oil Injection and Sampling"). Before sampling of the refrigerant-
lubricant mixture, the system was operated for three hours to allow the refrigerant and
lubricant to fully mix. The sampling and calculation procedure for oil concentration was
based on ASHRAE Standard 41.4-1984 (ASHRAE 1984).
For two-phase flow conditions at the inlet of the test section, the quality was
determined from the energy balance on the heat tape. The overall heat transfer coefficient,
UA, for the insulation section was determined from measured data for single-phase flow
conditions and an energy balance on the test section.
Where QH is power input to the heat tape, Qr is the rate that heat energy is transferred to the
refrigerant, Ql is the rate that heat energy is lost through the insulation, nv is the mass
flowrate of refrigerant, and Ti m and To m are the mean temperatures at the inside and outside
of the insulation, respectively. Based on the overall heat transfer coefficient and measured
data for two-phase conditions, the enthalpy at the exit of the heat tape was determined by :
UA=(Q„
Qr ~~ % (^o,r ~^l,r )
Qi = Q„-Q,
(3.1)
(3.2)
(3.3)
Ql = UA(T^m - Tijm)
(3.4)
18
-------
u - Qh Ql . t,
"os . T 'Hjr
mr
(3.5)
Finally, the quality was evaluated from the enthalpy calculated using Equation (3,5) and the
pressure at the inlet of the test section. The overall heat transfer coefficients were checked by
comparing the results of Equation (3.1) with the curve fitted results as a function of power
input and mean operating temperature of the insulation. The maximum difference between
these two methods was within ±2.0%,
19
-------
CHAPTER IV
EXPERIMENTAL RESULTS FOR R32/125/134a (23%/25%/52%)
The ternary refrigerant mixture of R32/125/134a (23%/25%/52%) (Tradename
AC9000) was tested in the apparatus as described in chapter two. Test conditions for all tests
were a combination of condensing temperatures ranging from 95°F (35.0°C) to 125°F (51,7°
C) and evaporating temperatures ranging from 30°F (-1.1°C) to 50°F (10°C). Short tube
orifices of length 0.5 in (12.70 mm), 0.75 in (19.05 mm), and 1 in (25.4 mm) with diameters
ranging from 0.0432 in (1.09 mm) to 0.0763 in (1,94 mm) were tested at all condensing and
evaporating conditions. The following describes the results for the ternary refrigerant mixture
(AC9000) for the stated flow conditions and oil contamination mass percentages.
PURE R32/125/134a (23%/25%/52%)
The following section discusses the effects of downstream pressure, upstream
subcooling/quality, upstream pressure, diameter, and length on the mass flowrate of
refrigerant through a given orifice geometry. Appropriate figures are also introduced to
represent the effects of varying the above parameters on the mass flowrate through the short
tube. The flow model introduced in chapter VI is used in some of the figures to aid the reader
in following the trends of the data.
Effects of Downstream Pressure on Mass Flowrate
When the upstream pressure was greater than the saturation pressure corresponding to
the given upstream temperature, the mass flowrate of refrigerant was generally insensitive to a
change in downstream pressure (Figure 4.1). Mass flowrate varied by less than 2% from its
20
-------
135
125
115
105
v *~
V*-
R32/12»134a
<23%rt5V52%)
Pup = 1,87 MP#
L=12.7mm
0=1.341 mm
Subcooling/Qusllty
~ 1I.1C
¦ 5.6C
A28C
X0.8C
*320%
75
625
675
725 775
Downstream Pr««*ur« (kPa)
825
Figure 4.1: Flow dependency on downstream pressure for a short tube with length 0.5
inand diameter of 0.0528 in.
value at the highest downstream pressure tested. For downstream pressures below the
saturation pressure, approximate choking flow conditions were typically established in the
short tube orifices. Choked flow is achieved when mass flow reaches a maximum value as the
downstream pressure is lowered. Approximately choked flow was evident for all tests.
Because heat pumps and air conditioners operate at evaporating pressures lower than
the saturation pressure, approximately choked flow would be the main operating condition for
all upstream temperatures. Figure 4.1 was typical of the behavior of the other orifices tested
at different downstream pressures. For all subcooling levels and two-phase qualities tested in
the present study, the mass flowrate was almost constant as the downstream pressure was
decreased. For a short tube with a length of 0.5 in (12.7 mm) and diameter of0.0528 in (1.34
mm), mass flowrate varied by less than 2% for all subcooling levels and qualities. These
trends were observed in the previous research (Kim, 1993, Aaron and Domanski, 1990).
21
-------
Effects of Upstream Subcooline/Oualitv
Figure 4.2 shows the mass flowrate as a function of subcooling/quality for three
upstream pressures and all downstream pressures. Please note that the negative subcooling
represents a percent quality. The general trend seen in this figure was consistent with the
previous results obtained for R22 and R134a (Kim and O'Neal, 1993a, 1993b). The
refrigerant flowrate increased as the upstream subcooling increased, and decreased as the inlet
quality increased. It should be noted that in Figure 4.2, there is a scale change due to the
representation of percent quality as negative numbers.
Abrupt drops in flowrate were seen as inlet conditions progressed from saturated
liquid (zero percent quality) into the saturation region. For an upstream pressure of 221 psia
(1524 kPa), flowrate decreased 21% from 205 lb/h (93.2 kg/h) to 162 Ib/h (73.4 kg/h) as the
quality increased from 0% to 1.7%. For an upstream pressure of 271 psia (1870 kPa),
flowrate decreased 18.5% from 210 lb/h (95.3 kg/h) to 171 lb/h (77.6 kg/h) as quality
increased from 0% to 3.2%. These trends are consistent with the previous work performed by
Kim and O'Neal (1993a, 1993b).
The variation of mass flowrate with subcooling/quality for several different diameters
can be seen in Figure 4.3. As the diameter increased, the slope of the subcooling line
increased. For two phase entering the short tube, the slope appeared to decrease slightly as
the diameter was increased. In the subcooling region, the mass flowrate increased an average
of 32.5% as subcooling varied from 0°F (0°C) to 20°F (11.1°C). In the two phase region,
mass flowrate decreased an average of 18% as quality was increased from 0% to 2%.
22
-------
«t
m
R32/125/134a
(23%/25%/52%)
Increasing
pressure
L*12.7 mm
D»1.34mm
All downstream
pressures
Upstream
Pressure
¦ 1524 W*j
~ 1870 tf*
A2271kP«
Lines Represent the Model
—f 1 h—t ~—l -t 1 l
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 S 10 11 12 13 14 15 16 1? 18 19 20
Quality |-%) / Subcoollng (#C)
Figure 4.2: Flow dependency on subcooling/quality for three upstream pressures for a
short tube with length 0.5 in (12.7 mm) and diameter of 0.0528 in (1.34 mm).
330
at
8
s
R32/125/134a
<23%/25%/52%)
Pup»187u kPa
Alt downstream
pressures
Diameters
~ 1.097 mm
¦ 1.3*1 mm
41.71? mm
X 1.938 rtfn
lines Represent the Model
Note Scale Change
30 f 4 -•¦¦-) ¦— ¦¦¦~ "I" • 1'-' ['1 "1 I I t 1 'I 1
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 S 10 11 12 13 14 15 16 17 18 19 20
Quality f.%} 15ubcoo»ng (*C) ;
Figure 4.3: Flow dependency on subcooling/quality for three diameters and upstream
pressure of 271 psia (1870 kPa) at ati downstream pressures.
23
-------
Effects of Upstream Pressure
Figure 4.4 shows the variation in mass flowrate with upstream pressure at different
levels of subcooling/quality. As the upstream pressure was increased, the mass flowrate
increased in a linear fashion. This trend was maintained even though the upstream pressure
was as high as 329 psia (2271 kPa) corresponding to an evaporating temperature of 125°F
(51.7°C). The slope of each line was approximately linear and increased with an increase in
subcooling. This increase in slope appeared to decrease with an increase in diameter. For two
phase at the inlet of the short tube, Figure 4.4 shows that mass flowrate averaged 18% lower
than the mass flowrate at saturated conditions over the range of upstream pressures. (Please
note that these figures include all downstream pressures.)
Effects of Short Tube Diameter
The variation in mass flowrate with short tube diameter is shown in Figure 4.5. The
effects of the short tube diameter on flowrate was consistent with the results of R22 and
R134a (Kim and O'Neal, 1993a, 1993b). For high subcooling the mass flowrate was
proportional to the diameter squared. As the diameter increased, mass flow increased with
slope increasing slightly with upstream pressure. This figure shows that the diameter strongly
affected mass flowrate; therefore, it is necessary to accurately measure diameter in order to
predict flowrate.
As upstream subcooling decreased (Figure 4.6), the effects of the short tube diameter
on flowrate decreased. The data near the saturation temperature (near zero subcooling)
tended to vary directly with the diameter. For two-phase flow entering the short tube,
flowrate was almost linearly proportional to the short tube diameter. This suggested that any
model of this behavior would need to correct for this variation in behavior near saturation and
at various qualities.
24
-------
R32/125/134a
(23%/ 25%/ 52%)
Increasing
Subcooiing
L=12.7mm
D=1.34 mm
Subcooling/Quality
~ 11.1C
¦ 5,6 C
4 2.8 C
O 0.0 C
*230%
60
Lines Represent Model
1500 1700 1900 2100 2300
Upstream Pressure (kPa)
2500
2700
Figure 4.4: Flow dependency on upstream pressure as a function of upstream
subcooiing/quality for a short tube with length 0.5 in (12.7 mm) and diameter
of 0.0528 in (1.341 mm).
25
-------
«
«
270
220
170
120
70
R32/125/134a
(23%/ 25%/ 52%)
Decreasing
Pressure
L»12.7 mm
Subcooling ¦ 11.1 C
All downstream
pressures.
Upstream Pressure
~ 1524kP»
¦ 1870 kPa
A 2271 kPa
Lines Represent the Model
1.25
1.75
Diameter (mm)
2.25
2.5
Figure 4.5; Flow dependency on short tube diameter for several upstream pressures and
subcooling of 20°F (11.1 °C).
335
285
235
£
I
| 185
UU
m
m
S 135
85
35
R32/125/134a
(23%/25%/52%)
Increasing
Subcooling
Pup= 1870 kPa
1=12.7 mm
All downstream
pressures.
Subcooling/Quality
~ 11.1 C
¦ 5.6 C
A 2.8 C
oo.sc
*2.50%
Lines Represent the Model
1.2 1.4 1.6 1.8
Diameter (mm)
2.2
2.4
Figure 4.6: Mass flow as a function of diameter for upstream pressure of 271 psia (1870
kPa), length of 0.5 in (12.7 mm), and various levels of subcooling/quality.
26
-------
Effects of Short Tube Leneth
Figure 4.7 shows the effects of increased short tube length on mass flowrate. As short
tube length was increased from 0.5 in (12.7 mm) to 1.0 in (25.4 mm) mass flow decreased by
an average of 9.5% from its value at the 0.5 in (12.7 mm) length. This decrease in mass flow
with increasing length was more exaggerated at the lower subcoolings. For the orifice given
in Figure 4.7, mass flow decreased from the value at 0.5 in (12.7 mm) by 3.3%, 8.4%, and
16.7% for subcoolings of20°F (ll.TC), 10°F (5.6°C), and 1.8°F (1 0°C), respectively. The
basic trends seen within this figure were consistent for all orifices tested.
140
130 -
120
1 110 -
1
- 100
w
m
5
90
80
70
>1
R32/125/134a
(23%/ 25%/ 52%)
Pup - 1870 kPa
D=1.34 mm
All downstream
pressures.
Subcooling
~ 11.1 C
¦ S.6C
A 1.0 C
Lines Represent the Model
10 12 14 16
18 20 22
Length (mm)
24
26
26
30
32
Figure 4.7; Effects of length on mass flow for upstream pressure of 271 psia (1.9 MPa) and
diameter of 0.0528 in (1.341 mm).
27
-------
MIXTURES OF OIL AND R32/125/134a (23%/25%/52%)
This section presents the experimental results obtained during examination of the flow
characteristics of the ternary refrigerant mixture and oil through the various short tube
orifices. Discussion with the advisory committee directed testing toward oil concentrations of
1% to 3%. It was agreed that oil concentrations of 1% to 3% were normally seen circulating
in a heat pump or air-conditioning system. The mass percentage of oil was set at 1,0% for
testing of all the short tube diameters at all upstream pressures and the median downstream
pressure which corresponded to evaporating conditions of 40°F (4.4°C). The mass flowrate
ratio, mR ,was calculated to compare the mass flowrate of pure refrigerant and oil/refrigerant
mixtures. The mass flow ratio, mR, was defined as:
mass flowrate of oil and refrigerant mixture
mR (4.1)
mass flowrate of pure refrigerant
Due to the limited number of data points available at particular points of interest, the
flow model developed in succeeding chapters is used to represent the basic trends of the data.
This is necessary because exact duplication of test conditions between the pure refrigerant
tests and the oil/refrigerant mixture tests is not possible.
General Trends
Figures 4.8 and 4.9 show the effects of oil concentration on mass flowrate for a given
geometry with a range of subcoolings/qualities and upstream pressures. These figures
revealed that the mass flowrate remained within 5% of the pure value at all upstream
pressures and subcoolings. For two-phase flow at the entrance of the short tube, the addition
of oil to the refrigerant mixture increased mass flow by more than 12%. Previous research
showed that increasing the oil concentration beyond a certain percentage would cause mass
28
-------
flow to drop sharply. Generally, mass flow would drop sharply for oil concentrations greater
than 2% to 2.5% in keeping with trends observed for R134a.
Figure 4.9 shows the effects of upstream pressure and oil concentration on the mass
flow ratio for a fixed upstream subcooling of 10 °F (5.6 °C). The trends plotted show that the
Model Comparison
¦'up ~ 1870 kPa
12 7 mm, D=1.34 mm
R32/125/134a
(23%/ 25%/ 52%)
Subcooina /Qualy
11.1 C
1,04
A"***
\ Increasing quality
0.6 0.8 1
Oil Conc«ntr«atlon (%)
Figure 4.8: Mass flow ratio as a function of oil concentration for upstream pressure of 271
psia (1870 kPa), length of 0.5 in (12.7 mm), diameter of 0.0528 in (1.34 mm),
and several subcoolings/qualities.
29
-------
R32/125/134a
(23%/ 25%/ 52%)
Model Comparison
Subcooling * 5 J C
Up*tr»«m F*essure
L»12.7 mm, t>1.34 mm
—•—1524 kPa
- -1870kPa
—* - 2271 kPa
0.95
0
0.2
0.4 0.6 0.8
Oil Conccntrcatlon (%)
1.2
1.4
Figure 4.9: Mass flow ratio as a function of oil concentration for all upstream pressures with
length of 0.5 in (12.7 mm), diameter of 0.0528 in (1.34 mm), and subcooling of
10 °F (5.6 °C)
mass flow ratio is lower for the higher upstream pressures. For the upstream pressure of 221
psia (1524 kPa), the mass flowrate was reduced by 3.1% compared to a reduction of less than
4.7% for an upstream pressure of329 psia (2271 kPa).
Effects of Upstream SubcooUne/Oualitv
Figure 4 .10 shows the variation in mass flowrate as a function of upstream subcooling
for a fixed geometry and a range of upstream pressures. At high levels of subcooling, the
addition of oil decreased flowrate from the pure case by approximately 3%. For the given oil
concentration, a decrease in upstream subcooling caused a decrease in mass flow. The mass
flow ratio at an upstream pressure of 221 psia (1524 kPa) decreased by approximately 2% as
upstream subcooling dropped from 20°F (11.1°C) to saturated conditions.
i
Effects of Upstream Pressure
30
-------
The flow dependency of the oil/refrigerant mixture upon upstream pressure can be
seen in Figure 4.11. The mass flowrate increased with increasing upstream pressure even for
the oil/refrigerant mixture. One possible explanation for the lower mass flow ratio at the
higher upstream pressures could be the missibility of the oil in the refrigerant at the higher
temperatures. Even though subcooling was constant for a given line in Figure 4.11, higher
upstream pressures meant higher upstream temperatures. Mass flowrates for the 20°F
(11.1°C) subcooling level were generally within ±3% of pure refrigerant flowrates. For
subcooling levels below 10°F (5 .6°C), the addition of oil tended to decrease the mass flowrate
more rapidly than at higher subcooling levels (Figure 4.11). On average flowrates decreased
by 3.5% for subcoolings below 10°F (5.6°C). Similar trends were observed in the previous
work on R-134a (Kim, 1993). Two-phase conditions at the short tube entrance showed that
the addition of oil caused flowrate to decrease by a maximum of 9% with the average
reduction being 6%.
1.000
oaso
_ 0 .980
| 0.970
| 0.960
| 0.950
«
«
I 0.940
0.930
0.920
Quaiittf.*)/Subcooling (+C)
Figure 4.10: Mass flow ratio as a function of upstream subcooling for several upstream
pressures.
Increasing
Pressure
Note the scale change.
L« 12.7 mm
D« 1.341 mm
All downstream
pressures.
Upstream
Pressure
1524 kPa
1870 kPa
-2271 kPa
R32/125/134a
(23%/25%/52%)
.5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
31
-------
0.99 y
0.98
0.96 -
?
0.97
1
0.97
6
0.96
*
0.96 ¦¦
i
1L.
0.95
m
8
0.95 -
SE
0.94 •
0.94 •
0.93
R32/125/134a
(23%/25%/ 52%)
*
t
2.5%
L
¦ 12,7 mm
D-1.34 mm
All downstream
pressures.
Subcooling/Quality
11.1 c
— — 2.8 C
o
0
1
•
1
— - - 2.50%
1500
1700
1900 2100
Upstream Pressure (It Pa)
2300
2500
Figure 4.11: Mass flow ratio as a function of upstream pressure for all upstream subcoolings
and 1% oil.
SUMMARY OF RESULTS FOR R32/125/134a (23%/25%/52%)
For the conditions of the present study, the existence of choked flow conditions was
verified from plots of the mass flowrate of refrigerant as a function of downstream pressure.
It was noted that weak establishment of choked flow may not promote system reliability and
constant control.
Upstream pressure was also examined as a dominant parameter affecting the mass
flowrate of refrigerant through the short tube orifice. As upstream pressure was increased,
mass flow increased in a linear fashion. The increase in the slope of the mass flow/upstream
subcooling line tended to decrease slightly with increases in short tube diameter. Increases in
upstream subcooling also tended to cause increases in mass flowrate for a given upstream
pressure.
32
-------
The variation in refrigerant mass flowrate with short tube diameter for the ternary
refrigerant mixture followed the same trends seen for the flow of R-22 and R-134a. For high
subcooling, the mass flowrate varied with approximately the square of the orifice diameter.
At subcooling levels near zero, the changes in flowrate with diameter were less pronounced.
For tworphase conditions at the short tube entrance, the flowrate was almost linearly
proportional to diameter.
The addition of oil to the ternary refrigerant had little effect on mass flowrate at higher
subcooling levels. The flowrate generally remained within 5% of the pure case at subcooling
levels of 20°F (11.1°C). If oil concentrations were increased further, the rapid drop in mass
flow seen in past tests with R22 and R134a may have been more evident. The variations in
flowrate with upstream pressure followed the same trends seen in the pure case. Increases in
upstream pressure caused a linear increase in the mass flowrate. However, the rate of increase
was lower for the oil/refrigerant mixture.
33
-------
CHAPTER V
EXPERIMENTAL RESULTS FOR R32/125 (50%/50%)
The (near) azeotropic refrigerant R32/125 (50%/50% on a mass percentage) was
tested in critical flow through short tube orifices of length 0,5 in (12,7 nun), 0.75 in (19,05
mm), and 1.0 in (25.4 mm) with diameters ranging from 0.0432 in. (1 09 mm) to 0.0763 in,
(1.94 mm). Simulated condensing temperatures ranged from 80°F (26.7°C) to 125°F (51.7°
C) with evaporating conditions of30°F (-1.11°C) to 50°F (10.0°C). Upstream pressure
corresponding to the various condensing temperatures ranged from a peak value of 461 psia
(3176 kPa) to 310 psia (2136 kPa). Downstream pressure, upstream pressure, upstream
subcooling/quality, short tube diameter, and short tube length were studied to determine their
effects on refrigerant mass flowrate.
PURE R32/125 (50%/50%)
The following sections describe the effects of the above parameters on refrigerant
mass flowrate through the short tube orifice. The figures introduced below represent the
general trends in mass flow for the conditions under consideration. Where necessary, the flow
model developed for the R32/125 mixture is used in the figures to help the reader follow the
basic trends of the data.
Effects of Downstream Pressure on Mass Flowrate
For the case of the binary refrigerant mixture, upstream pressures averaged much
higher than the saturation pressure corresponding to the given upstream temperature. This
meant that approximately choked flow conditions existed for all tests. Figure 5.1 shows the
variation in mass flowrate with downstream pressure for all subcooling/qualities. At
34
-------
155
145
€ 135
| 125
| 115
X
105
95
Downstaam Pressure (kPa)
Figure 5.1: Flow dependency on downstream pressure for a short tube of length 0.5 in (12.7
mm) and diameter of 0.0528 in (1.341 mm) with upstream pressure of 380 psia
(2618 kPa).
subcooling levels of 20°F (11.1°C), mass flowrate varied by less than 0.25% over the range of
downstream pressures. These figures showed that for the high operating pressures of the
binary refrigerant mixture, approximately choked conditions were well established at all
downstream pressures visited in the normal operating ranges of heat pumps and air-
conditioners.
Effects of Umtream SubcooIine/OuaUtv
Mass flowrate as a function of subcooling/quality is shown in Figure 5.2. The trends
presented were consistent with the results seen for the ternary refrigerant mixture. As
subcooling increased from 0°F to 20°F (11.1°C), mass flowrate increased as a second order
polynomial. The figure shows that mass flowrate increased by an average of 35% as
subcooling increased from 0°F to 20°F (11.1°C) for all upstream pressures tested. Refrigerant
flowrate decreased as the inlet quality increased. The disagreement seen between the model
and the data in the two-phase region can be attributed to the error in calculating refrigerant
R32/125
{50%/ 50%)
a» m m ¦
Pup=2618 kPa
L-12.7 mm
D*!34 mm
Subcooling
~ 11.1 C
¦ 5.6 C
A 0.9 C
00
800
900
1000
1100
1200
1300
35
-------
f
M
105J -
R32/R125
(50%, 50%)
Pup*2618 kPa
L« 12.7mm
D« 1.34 mm
Ml downstream
pressures.
Upstream
Pressure
«2136kfti
*2618 Id*
A 3176
Note the scale change.
Lines represent the model.
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Quality (•*) I Subcooling (~€}
Figure 5.2: Flow dependency on subcooling/quality for all upstream pressures with length of
0.5 in (12.7 mm) and diameter of0,0528 in (1.341 mm).
quality. The error in refrigerant quality calculation averaged 0.007 (Ibm of vapor/ Ibm of
refrigerant).
For two-phase conditions at the inlet of the short tube, there was a sharp decrease in
refrigerant mass flowrate as compared to the saturated conditions. Table 5.1 summarizes the
change in mass flowrate for qualities between 0% and 3% for an upstream pressure of 380
psia (2618 kPa). Although the percent change in mass flowrate for two-phase at the short
tube entrance was approximately constant, the magnitude of the flow drop varied with
diameter. This was to be expected since mass flowrate has been shown to increase in
proportion to the orifice diameter raised to the power of 2.5.
36
-------
Table 5.1: Mass Flowrate Change for Two-Phase at Orifice Inlet
Diameter, in.
(mm)
Flowrate Change, lb/h (kg/h)
Difference,
lb/h (kg/h)
Percent
Change (%)
0% Quality
3% Quality
0.0432(1.09)
139.4 (63.3)
107.2 (48.6)
32.2 (14.7)
-23.0
0.0528 (1.34)
213.9 (97.0)
165.2 (74.9)
48.7(22.1)
-22.7
0.0674 (1.71)
375.5 (170.4)
291.4(132.2)
84.2 (38.2)
-22.3
0.0763 (1.94)
509.11 (230.9)
396.0 (179.6)
113.1 (51.3)
-22.2
* Pup = 379.66 psia (2617.7 kPa), length = 0.5 in (12.7 mm)
Effects of Upstream Pressure
Figure 5.3 shows the variation in mass flowrate with upstream pressure at different
levels of subcooling/quality. Mass flowrate tended to increase almost linearly as the upstream
pressure was increased. The slope of the mass flowrate/upstream pressure line increased
slightly with an increase in subcooling. The trends presented were consistent with the results
seen for the ternary refrigerant mixture even though operating upstream pressures were 40%
higher than those for the ternary mixture. For the figure shown, the slope increased by 14%
as subcooling increased from 0°F to 20°F (11.1°C). For two-phase conditions at the inlet of
the short tube, mass flowrate averaged 31% lower than at a subcooling level of 20°F (11.1°C)
and 7% lower than at saturated conditions. This trend was evident for all diameters tested
with the additional trend of an increase in slope as diameter was increased. For example at a
subcooling of 10°F (5.6°C), the slope increased from 0.219 Ib/h/psia (0.686 kg/h/kPa) to
0.652 lb/h/psia (2.038 kg/h/kPa) as the diameter varied from 0.0432 in (1.09 mm) to 0.0763 in
(1.94 mm). Please note the figure includes all downstream pressures.
37
-------
160 j
150 ¦
140 ¦
130 ¦
f
£
120
1
110 ¦
m
*
at
100 -
90-
80
70-
R32/125
(50%/ 50%)
£
a-
L*12 .7 mm
D=1,34 mm
Al Downstream
Pressure*
Subcooling/Quality
~ 11.1 C
¦ 5.5C
A 2.7 C
O 0,8 C
*2%
Lines Represent the Mode!
2000 2200 2400 2600 2800 3000
Upstream Pressure (kPa)
3200
3400
3600
Figure 5,3: Flow dependency on upstream pressure for all subcooling/qualities and
downstream pressures with length of 0.5 in (12.7 mm) and diameter of 0.0528 in
(1.341 mm).
38
-------
Effects of Short Tube Diameter
Figure 5.4 shows the variation in mass flowrate with orifice diameter at 20°F (11.1°C)
of subcooling and all upstream pressures. While the ternary refrigerant mixture mass flowrate
tended to vary with diameter raised to the 2.2 power, the binary mixture mass flowrate tended
to vary more closely with diameter raised to the 2.5 power. Table 5.2 shows how this trend
developed for several different subcooling/qualities when the data were fit to an equation of
the form:
m-cx+c2- (5.1)
The last row in the table gives the value of the coefficient, C3, in Equation (5.1).
Table 5.2: Variation of Mass Flowrate with Orifice Diameter
Length = 0.5 in
(12.7 mm)
Diameter, in (mm)
Mass Flowrate, lb/h (kg/h)
Subcooling/Quality
20°F (11,1°C)
5°F (2.7°C)
3%
0.0432(1.09)
213.5 (96.9)
159.2 (72.2)
117.3 (53.2)
0.0528 (1.34)
325.1 (147.5)
244.5(110.9)
180.5 (81.9)
0 0674 (1.71)
551.8 (250.3)
426.8 (193.6)
317.9(144.2)
0.0763 (1.94)
728.4 (330.4)
575.5 (261.0)
431.5 (195.73)
Cj, coefficient
2.33
2.58
2.66
* Upstream pressure of379.66 psia (2617.7 kPi) and all downstream pressures.
This calculation revealed the polynomial characteristics of the mass flowrate as a function of
orifice diameter for the binary refrigerant mixture. The above polynomial fits reveal the
necessity of measuring the orifice diameter accurately.
39
-------
385
L*12.7 mm
All downstream
pressures.
Upstream
Pressure
336
285 - *
1
u.
«
*
m
2
235
185 ••
Increasing Pressure
Lines Represent the Model
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 23 2.4
1
Diameter (mm)
Figure 5.4: Flow dependency on short tube diameter for all upstream pressures at 20"F
(11.1°C) subcooling and all downstream pressures.
40
-------
Effects of Short Tube Length
Figure 5.5 shows the effects of increasing the short tube length for the given
conditions. As length increased the mass flowrate of refrigerant decreased slightly. For the
range of lengths being tested, the mass flowrate decreased an average of 4.5%. As subcooling
decreased from 20°F (11.1°C) to 0°F, the slope of the mass flowrate versus length curve
increased by 42% varying from -28.4 lb/(h in) [-0.508 kg/(h mm)] to -16.6 lb/(h in) [-0.296
kg/(h mm)]. The trends shown below were consistent with all the orifices tested.
175
165 4
155
145
% 135
1 125
S 115
«
S
105 4
95
85
75
R32/R125
(50%/50%)
t -
*
Decreasing *ubcooing
L
Pup=2618 kPa
D=1.341 mm
Lines represent
model.
Subcooling / Quality
12 14 16 18 20 22 24
Length (mm)
26
-11.1 C
¦5.6C
OC
•3%
28
30
32
Figure 5.5: Effect of length on mass flowrate for short tube of diameter 0.0528 in (1.341
mm), upstream pressure of380 psia (2618 kPa), and several subcoolings/qualities.
41
-------
MIXTURES OF OIL AND R32/125 (50%/50%)
Tests were performed for all orifices with oil added to the pure refrigerant to more
closely simulate actual operating conditions for air conditioners and heat pumps. Oil mass
percentage was set at approximately 2.2%. Testing was performed at various upstream
pressures and at the median downstream pressure of 132.7 psia (915 kPa). Oil concentration
was determined using the methods described in chapter two (pure refrigerant method).
General Trends
Figure 5,6 show the variation in mass flowrate ratio, m,, as a function of oil
concentration for several subcooling/qualities. The apparent scatter in the data was due to the
large dependency of mass flowrate on the degree of upstream subcooling. A general trend of
the form seen for the ternary mixture was again apparent for the binary mixture. At an oil
concentration of 2.2% with subcoolings above 10°F (5.6°C), the refrigerant remained within
1.5% of the pure case. The mass flow ratio generally tended to decrease with decreasing
subcooling. The two-phase data showed an increase in mass flow ratio as quality increased
from 1% to 5%. For a fixed subcooling, mass flow ratio tended to decrease as upstream
pressure increased. This could be a consequence of the solubility of the oil in the refrigerant
at different temperatures (Corr et al, 1994). These trends were seen to apply for all orifices
and upstream pressures tested.
The main emphasis of Figure 5.6 should be that oil concentrations lower than
approximately 2% cause less than a 2% variation in mass flowrate as compared to the pure
case. This was true of all the orifices tested. Additional data for lower oil concentrations
would clarify the exact form of the mass flow ratio and oil concentration function. However,
the flow trends shown seemed to agree with previous trends seen for the ternary refrigerant.
42
-------
s
5
1.03
1.02
1.01
1 I
0.99 '
0.98
M
Z 0.97
0.96
0.95
R32/125
(50%/ 50%)
X
5%
i - .
1%
0.5
1.5 2
CXI Concentration (%)
Pup = 2618 kPa
L ¦ 12.7 mm
D
¦ 1.341 mm
Subcooling/Quality
•—11.1 c
- ~ -5.6C
— d- -0C
—* - 1%
—*— 5%
2.5
Figure 5.6: Flow dependency on oil concentration for short tube with length of 0.5 in (12.7
mm), diameter of0.0528 in (1.341 mm), several subcooling/qualities, and
upstream pressures of380 psia (2618 kPa).
43
-------
Effects of Upstream Subcooline/Oualitv
Figure 5.7 shows the flow dependency on upstream subcooling for the binary
refrigerant mixture with 2.2% POE oil flowing through the 0.0528 in. (1.34 mm) diameter
orifice. All upstream pressures were included in the figure. The mass flow ratio was
calculated based upon the method introduced in chapter four.
At subcooling levels of20°F (11.1°C), the addition of oil to the pure refrigerant
caused the mass flowrate to remain essentially constant as compared to the pure case. For all
diameters and subcoolings, the mass flowrate for the oil refrigerant mixture remained within
5% of the pure case. As the subcooling was lowered, the mass flowrate decreased below the
levels seen for the same conditions in the pure case. At subcooling levels of 10°F (5.5°C), the
mass flowrate averaged 2% lower than the pure case for all diameters. This trend continued
with the mass flowrate averaging 2.5% lower than the pure case at saturated upstream
conditions for all diameters. In the low quality two-phase region, the addition of oil decreased
mass flowrate by as much as 9.5% from the pure case. As the quality increased, the mass flow
ratio approached unity. Thus, for the high inlet quality region, the presence of oil did not
substantially affect the mass flow.
The drop in flowrate at the lower subcooling levels for the 0.5 in (12.7 mm) orifice
was consistent with results presented by Kim (1993) for R134a with a PAG oil. The binary
refrigerant/oil mixture showed the same trends as the R134a/PAG mixture in the subcooled
and two-phase regions.
44
-------
Effects of Upstream Pressure
The flow dependency on upstream pressure for the oil/refrigerant mixture is shown in
Figure 5.8. This figure shows the trends for a 0.0674 in. (1.71 mm) diameter orifice for all
subcoolings. The weak dependence of flowrate ratio on upstream pressure indicated that the
mass flowrate for the oil/refrigerant mixture tended to follow the same trends as seen for the
pure case. The main emphasis of this figure was that mass flowrate was lowered for all
upstream pressures and subcoolings of 10°F (5.6°C) or less. The figure shorn that mass
flowrate averaged approximately 1.8% lower than the pure case for the 0.0674 in. (1.71 mm)
diameter orifice at subcoolings of 10°F (5.6°C) or less. This trend was extended to all
diameters with mass flowrate averaging 1% lower than the pure case for subcoolings of 10°F
(5.6°C) or less.
For these oil tests, the length of the short tube was also varied. Short tubes of length
0.5 in (12.7 mm), 0.75 in (19.05 mm), and 1.0 in (25.4 mm) were tested. These orifices had
diameters of0.0528 in (1.341 mm) and 0.0674 mm (1.71 mm). At the oil concentration of
2 .15%, mass flow rate remained within 1% of its value for the pure refrigerant at all lengths
and for the two diameters tested. Therefore, mass flow trends were consistent with those
produced by the pure refrigerant.
45
-------
-*85-
*
m
Increasing v
Pressure 0.90'
0.85
-em-
R32/125
(50%/50%)
Note the scale change.
2.2% POE Oil
L « 12.7 mm
D «= 1.341 mm
All downstream
pressures.
Upstream
Pressure
-2136 tf*
-2618 kRa
—317« kP&
-4 -3 -2 -1 0 1 2 3 4 S 6 7 8 9 10 11 12
Quality (-*4) I Subcooling (+C)
Figure 5.7: Flow dependency on upstream subcooling at all upstream pressures for the
0.0528 in (12.7 mm) diameter orifice.
1.00
0.98
?
9
&
5 0.96
£
i
| 0.94
m
m
m
S
0.92
0.90
2000 2200 2400 2600 2800 3000 3200 3400 3600 '3800
Upstream Pressure (kPa)
Figure 5.8: Flow dependency on upstream pressure for the short tube with diameter of
0.0674 in. (1.71 mm) and length of 0.5 in (12.7 mm).
2.2% POE Oil
L
¦ 12.7 mm
D
* 1.71 mm
Ml downstream
pressures.
Subcooling/Quafity
———11.1 C
S.6C
—¦ - -2.8C
— 1%
46
-------
SUMMARY OF RESULTS FOR R32/I25 (50%/50%)
For the high operating pressures of the binary refrigerant mixture, choked flow
conditions existed at all downstream pressure. Regardless of the diameter of the short tube,
the mass flowrate varied by less than 1% for the range of downstream pressures tested.
As the upstream subcooling decreased, the mass flowrate of refrigerant decreased.
Table 5.3 shows the trends in mass flowrate for decreasing subcooling. As subcooling
decreased from 20°F (11. PC) to 0°F, mass flowrate decreased an average of 27%, For two-
phase at the orifice inlet, the mass flowrate decreased sharply. Mass flowrate for all diameters
dropped an average of 23% as quality was increased from 0% to 3%. The magnitude of the
resulting decrease in mass flowrate for two-phase conditions was higher for larger diameter
orifices. This meant that the larger orifices tended to be more affected by two-phase
conditions at the entrance.
The slope of the mass flowrate/upstream pressure curve increased as upstream
subcooling was increased. This trend continued for all diameter orifices. For two-phase at
the orifice inlet, the mass flowrate averaged 18% lower than at saturated conditions for all
diameters.
Mass flowrate was affected more by short tube diameter for the binary refrigerant
mixture than for the ternary refrigerant mixture. While the ternary refrigerant mixture mass
flowrate varied approximately with the square of the orifice diameter (diameter raised to the
2.2), the binary refrigerant mixture mass flowrate tended to vary more closely with orifice
diameter raised to the power of 2.5. This was true for all diameters and upstream
subcooling/quality conditions.
47
-------
Table 5.3: Percent Change in Mass Flowrate for a Change in Subcooling/Quality
Length of
0.5 in
(12.7 mm)
Pup = 310 psia
(2136 kPa)
Pup = 380 psia
(2618 kPa)
Pup = 461 psia
(3176 kPa)
Subcooling / Quality
Subcooling / Quality
Subcooling / Quality
Diameter,
in (mm)
20°F-*0°F
11.1°C-*0°C
0%-*3%
20°F-*0°F
n.i°c-+o°c
0o/<^3%
20°F-*0°F 0%-»3%
ll.l°C-*08C
0.0432
(1.09)
-31.5
-23.1
-28.7
-23.0
-27.4 -22.9
0.0528
(1.341).
-29.6
-22.8
-28.2
-22.7
-26.9 -22,6
0.0674
(1.71)
-27.1
-22.4
-25.8
-22.3
-24.7 -22.3
0.0763
(1.94)
-25.1
-22.2
-23.9
-22.2
-23.0 -22.1
The addition of oil to the pure refrigerant caused flow trends that were also observed
in the ternary refrigerant mixture. At subcooling levels of 20°F (11.1°C), the mass flowrate
change was negligible. As subcooling decreased, the decrease in mass flowrate as compared
to the pure case followed a seemingly linear trend dropping by approximately 4% for all
diameters tested. Increasing the length of the short tube for the oil/refrigerant mixture caused
less than a 1% change in mass flowrate.
48
-------
CHAPTER VI
SEMI-EMPIRICAL MODEL DEVELOPMENT
Due to complicated two-phase flow conditions in the orifice and a step pressure
gradient at the exit plane of the short tube, most previous investigators have chosen semi-
empirical flow models over analytical or numerical models for refrigerant flow through short
tubes. One approach to modeling two-phase flow through short tubes is to start with the
single-phase orifice equation and make corrections in it, This method has been used by
several previous researchers (Pasqua, 1953; Davies and Daniels, 1973; Mei, 1982; and Aaron
and Domanski, 1990).
The present flow model was basically derived from the single-phase orifice equation
with adequate modification of a theoretical equation to satisfy the flow characteristics through
short tube orifices. The developed flow model for both R32/125/134a (23%/25%/52%) and
R32/125 (50%/50%) covered single and two-phase flow at the inlet of the short tube with
consideration for oil contamination effects. This section discusses the governing equations
and coefficients for the semi-empirical flow model. The detail description of theoretical
equations will not be included here, but the detailed procedure can be found in the paper by
Kim and O'Neal (1994a).
The single-phase orifice equation used for orifices can be derived from equations of
continuity and energy with the given assumptions (ASME, 1971). The single-phase orifice
equation for a single-component, single-phase substance is given as:
m, = CA,^2y0p(P„p - P^j/O - p4) (6.1)
49
-------
where m3 is the mass flowrate for single -phase flow, C is a discharge coefficient to account
for friction and other effects, and P is the ratio of orifice throat diameter to upstream tube
diameter. The total mass flow for two-phase flow, mlp, can be related to the inlet quality, xup,
and single-phase mass flow rate, ms by the following relationship (Kim and O'Neal, 1994a;
Chisholm, 1967):
. 5g
m'p (\-xupy(\+aY+Y2fs
where Y is a variable that depends on the upstream quality, relative densities of the inlet vapor
and liquid, and another term, F, which is a function of the polytropic ratio, n, and the pressure
ratio of downstream to upstream, r. Y and F are given below:
r Pf
03
Y = p
1 -x^pj
(6.3)
-(¦
n-1 i-r If
„ ' | _ ,.(¦-!)/¦ ' rv» J
The variable a in Equation (6.2) depends on the cross sectional areas occupied by the liquid
and vapor (Chisholm, 1967).
When an arbitrary control volume (shown by dotted line in Figure 6.1) was drawn
around the short tube orifice with subcooled liquid at the inlet, it was noted that the
assumption of incompressible flow for Equation (6,1) was violated due to the fact that
flashing occurred inside of the short tube (Kim and O'Neal, 1993a). Once the flow flashed,
there was a density change. Because choked conditions were established just after the
flashing point, the flow rate was not a function of the pressure at the downstream control
surface. Therefore, the downstream control surface was reset to the inlet section before
flashing occurred (shown by continuous line in Figure 6.1).
50
-------
Subcooled Liquid Onset of Flashing
Two-Phase Fluid
Upstrei
Flow
Pdown
Downstream
New C.V. Full C.V. Metastable Liquid Core
Figure 6.1: Control Volume of the Mass Flow Model.
It was observed that the measured pressure at the inlet section of the short tube was
lower than (Kim, 1993). However, due to the existence of metastable liquid flow at the
inlet section of the tube, the temperature change anticipated from the pressure dip near the
inlet could be small within the new control volume. Therefore, the change of the liquid
density across the control volume may be assumed to be negligible because of small
temperature differences. Thus, the assumption of incompressible flow was approximately
satisfied by moving the downstream control surface.
Once the assumptions were examined with the new control volume, Equations (6.1)
and (6.2) had to be modified to satisfy both the flow characteristics through short tubes and
flow conditions within the new control volume. After dropping the term (1-p4) from Equation
(6.1) due to small values of P4 compared with unity (for current study, 0.1 < J3 < 0.2), a mass
flow model for both single and two-phase flow was derived by combining Equations (6.1) and
(6.2):
(6.5)
where,
C,= (i-x,ry(i+ay+Y')
(6.6)
51
-------
It should be noted that for single-phase flow entering the short tube, the mass flow rate,
was equal to M s (Equation (6.1)) because Ctp was unity. For two-phase flow entering the
short tube, m and m,p (Equation (6.2)) were identical.
To satisfy the pressure condition at the downstream control surface, Pf. which was the
pressure before the flashing occurred, was applied instead of Pdow„. The adjusted downstream
pressure, Pf, covered the assumption of incompressible flow and choked flow conditions. The
single-phase flow models were typically correlated by modifying downstream pressure and the
orifice constant. In this study, the orifice constant, C, was set equal to unity and Pf was
correlated with the experimental data. Due to the limited data for oil contamination, a
correction factor for oil contamination was not included in the present model. New
coefficients for the oil/refrigerant mixtures were calculated instead. Further testing of these
refrigerants at various concentrations of oil would be needed to properly correlate mass
flowrate with oil concentration. The final form of the model was given by:
* = CrA,j2r.P
-------
mixture effects. It should also be noted that for subcooled liquid entering the short tube, Ctp
was unity because xup in Equation (6.9) was set equal to zero.
After deciding basic normalized parameters included in each correction factor, a
correlation between correction factor and normalized parameters was determined using a non-
linear regression technique along with the experimental data. This technique minimized the
sum of the squares of the error between the model and the experimental data. This technique
did not take into account the errors in the measured variables. All coefficients were
determined to the number of digits presented in Table 6.1. The use of this degree of precision
is not necessary, but these numbers were presented to allow the reader to duplicate the results
given in this report. All coefficients included in the flow model are given in Table 6.1. Tables
6.2 and 6.3 list the 95% confidence intervals for the model used with the ternary and binary
refrigerant mixtures.
Based on all the measured data for pure refrigerants, the adjusted downstream
pressure, Pp was correlated with inlet subcooling, upstream pressure, downstream pressure,
short tube length, and short tube diameter. The liquid saturation pressure, Pm, was used as a
reference value for Pf, because flashing occurred when the pressure was near Psa!.
Pf = P^
where,
DR = D/Drtf
EVAP = (Pc-PdowJ/Pc (P is in absolute pressures)
LD = (L/D)
PRA = Pu/Pc (P is in absolute pressures)
SUBC = {Ttat-Tu^ITe (T is in absolute temperatures)
D - short tube diameter, in. (mm)
Awf = reference short tube diameter, 0.060 in. (1.524 mm)
bx+b2- PRAb> • LD* • SUBC** + b6 • PRAbl
+ bt • exp(b9 • DR * Llf1" ) + bu- EVAP
53
-------
Pc = critical pressure for a given refrigerant, psia (kPa)
Pdown - downstream (evaporator) pressure, psia (kPa)
Pm - saturated liquid pressure corresponding to upstream temperature, psia (kPa)
Tc = critical temperature for a given refrigerant, °R (K)
Table 6.1: Coefficients of Correction Factors in the Flow Model
Equations
Coefficients
R32/125/134a (23%/25%/52%)
R32/125 (50%/50%)
Pure
1% Oil
Pure
2.2% Oi
h
0.963034325
0.980538238
0.874805831
1.0501041
b2
4.2S6408416
4.957604391
3.131470913
6.3059865
b3
-0.278235435
-0.309919995
-0.214726407
0.0991388
*4
-0,043090943
-0.116219951
0.083394737
-0.0456261
Eq (6,8)
bs
0.916226528
0.906610038
0.901559277
0.9584592
b6
0.071794702
0.227476573
-0.020574536
-0.254071'
h
0.499098698
0.186773583
0.944446846
0.1371989
h
-0.208417565
-0.398196082
-0.418400083
-0.2765161
b9
-0.034680678
-0.030711793
-0.025322802
-0.0145891
bi0
1.844061084
1.587754176
2.33507746
2.512190
bu
-0.091235910
-0.134132834
0.068890172
0.130875;
«!
-4.45974577
-4.349745770
3.693038038
1.4276181
Eq(6.9)
a2
10.69467130
10.454571210
0.120175996
0.5307511
*3
-0.55303036
-0.663120121
0.194241638
-0.365456;
°4
0.39429366
0.323273661
0.022577667
0.0186699
Constants
Unit
R32/125/134a (23W25W52%)
R32/125 (50%/50%)
p
SI
4619.14 kPa
4949.65 kPa
1 c
English
669.95 psia
717.886 psia
V
SI
359.89 K
345.65 K
* c
English
647.80 °R
622.17°R
Yc
SI
1.2960x10'°
1.2960xl010
English
2.8953x10*
2.8953x10®
Reproduced from Jlifl
best available copy.
54
-------
Table 6,2: 95% Confidence Intervals for R32/125/134a
Equations
Coefficients
Pure
1.1% POE Oil
Lower
Upper
Lower
Upper
bi
0.963034325
0.963034325
-4.787001464
6.748077940
bi
3.1224119659
5,4504048657
3.699873309
6.215335472
b3
-0.4373237299
-0.1191471410
-0.331931505
-0.287908486
b4
-0.0885788530
0.0023969672
-0.254075896
0.021635994
b5
0.9162265277
0.9162265277
0.906610038
0.906610038
Eq, 6.8
b6
-1.1382600458
1.2818494506
0.227476573
0.227476573
t>7
-6.4449286196
7.4431260148
0.186773583
0.186773583
bg
-0.4652161714
0.0483810419
-16.002595330
15.206203167
b9
-0.1066567015
0.0372953458
-0.030711793
-0.030711793
bio
1.2161602881
2.4719618798
1.587754176
1.587754176
bi,
-0.2263526123
0.0438807918
-0.134132834
-0.134132834
ai
-4.9637146381
-3.955776907
-4.8537146381
-3.845776907
Eq. 6.9
a2
9.7390766871
11.650265915
9.7390766871
11.410165825
m
-0.6347830631
-0.471277658
-0.7448728241
-0.581367419
aj
0.3816792114
0.406908115
0.3106592124
0.3358881096
55
-------
"able 6.3: 95% Confidence Intervals for R32/125
Equations
Coefficients
Pure
1.1% POE Oil
Lower
Upper
Lower
Upper
b,
0.8747920941
0.874819568
0.814668545
1.285539821
b2
1.9838974355
4.279044391
2.941485847
9.670487248
b3
-0.4665078602
0.037055047
-0.225962204
0.42423984C
h4
0.0064426512
0.160346823
-0.173420786
0.082168574
bs
0.8091066774
0.994011876
0.833799837
1.083118756
Eq. 6.8
be
-0.0849233234
0.043774252
-0.629647111
0.121503545
b7
-9.0356913394
10.924585032
-0.199120275
0.473518185
b8
-6.2433121026
5.406511937
-8.601773326
8.048740954
b9
-0.3829220836
0.332276480
-0.636469775
0.607290238
bio
-5.7158555578
10.396010477
-13.126793997
18.151175594
bii
-0.0528574639
0.190637808
-0.32516S662
0.593340779
at
0.29247000809
7.0936060678
-4.0091047403
6.864340965!
Eq. 6.9
a2
0.01462620069
0.2257257910
0.0818249345
0.979677289?
a3
-0.40220973453
0.7906930106
-1.3182002460
0.587287714:
a4
-0.07816871690
0.1233240504
-0.1248108046
0.162150680*
Repfoduc&d from
best available copy.
Upstream pressure, Pup, was considered in the updated model (Equation. (6.7)), but it
did not adequately account for the observed slope change for flow rate with respect to
upstream pressure and subcooling. Therefore, the effects of the upstream subcooling were
correlated with the normalized subcooling, (T,al-Tup)/Tc and normalized upstream pressure,
/yPc.. Because the cross sectional area of the short tube, A„ in Equation (6.7) did not fully
correlate diameter effects on flow rate, a normalized form of diameter, DR, was included in
the correction of the adjusted downstream pressure, Pf. Due to non-ideal choking that occurs
56
-------
in orifices, the slight mass flow dependency on downstream pressure was considered using the
normalized downstream pressure, (Pc mPdow*yPc-
Because the two-phase correction factor, Cr defined by Equation (6.6) did not
include the effects of short tube geometry and boundary conditions at the downstream control
surface, some modifications were required. First, the Fin Equation (6.4) was set equal to
unity because of the difficulty in evaluation of pressure ratio, r, within the new control
volume. However, the effects of compressibility for vapor (the physical meaning in the value
of F) was considered by modifying inlet quality, xup (coefficients a, and a2 in Equation (6.9)).
Second, the correlation between the single-phase flow rate and liquid flow rate during two-
phase flow was modified by including the effects of a short tube diameter. The single-phase
mass flow, ms, was calculated at zero subcooling to obtain the continuity between the single
and two-phase flow rate. Thus, after setting SUBC-0 while keeping the coefficients of Pf
constant, the coefficients of Cp were determined from the experimental data for two-phase
entering the short tube.
The pf and p in the Equation (6.10) is the saturated liquid and saturated vapor density,
respectively, at a given upstream pressure which is equal to saturation pressure, Psan for two-
phase entering the short tube.
The presence of oil had a stronger effect on mass flowrate at low subcooling levels
than at high subcooling levels. The effects of the oil were partially dependent on upstream
subcooling and upstream pressure (Chapter IV and V). If more data were taken for several
1
(6.9)
where
(6.10)
57
-------
more oil concentrations, a correction factor for oil concentration, C0 .could be included in
equation 6.7. However, due to limited data for mass flow at different oil concentrations, the
present model only includes flow equation for the specific oil concentrations tested.
Using Equation (6.7) through (6.10), the mass flow rate at a given operating condition
and short tube geometry can be predicted. When applying the above equations, it should be
understood that the application of the flow model has a limited range due to the limited range
of the experimental data (Table 6.4). To apply the flow model successfully, some attention is
required in the following: (1) temperature and pressure are in their absolute values, and area
has units of in2 (m2), (2) xup should be set equal to zero (C^»=l) for calculation of single-phase
mass flow rate, (3) SUBC should be set equal to zero for calculation of two-phase mass flow
rate, and (4) the oil model does not cover every geometry included in the pure tests with two-
phase flow at the inlet of the short tube.
Table 6.4: Limitations on the Application of the Flow Model
Refrigerants
Parameter
Minimum
Maximum
R32/125/134a
(23%/25%/52%
)
L
0.5 in (12.70 mm)
1.0 in (25.40 mm)
D
0.0431 in (1.09 mm)
0.0763 in (1.94 mm))
221 psia (1524 kPa)
329 psia (2271 kPa)
P
4 down
78 psia (483 kPa)
p
* sat
Subcooling
0°F (0°C)
20°F (11.1°C)
Quality
0%
5%
Oil Cone.
0%
1.0%
R32/125
(50%/50%)
L
0.5 in (12.70 mm)
1.0 in (25.40 mm)
D
0.0431 in (1.09 mm)
0.0763 in (1.94 mm)
PUB
309 psia (1751 kPa)
461 psia (3176 kPa)
^down
111 psia(769kPa)
P
1 sat
Subcooling
0°F (0°C)
"20°F (11.1°C)
Quality
0%
5%
Oil Cone
0%
2.4 %
58
-------
GOODNESS OF FIT
The detail comparison of the present flow model with the experimental data is
included in the Appendix A. Generally the prediction of mass flowrate fit the experimental
data well for a wide operating range. An absolute value percent difference as defined by the
following equation was used to determine the goodness of fit for each model.
I calculated-actual
100%J <6"
Table 6,5 compares the model with the experimental data over the entire range of geometries
and conditions tested. For the pure ternary mixture (AC9000) with both single phase at the
Table 6.5: Overall Goodness of Fit for Mass Flow Model Using 95% of the Data
R32/125/134a (23%/25%/52%)
R32/125 (50%/50%)
Absolute Value
Percent
Difference
Pure
Oil
Pure
Oil
Mean
2.814
1.629
1.999
1.882
Standard
Deviation
2.050
1.174
1.904
1.568
Maximum
8.420
4.145
9.394
8.296
inlet of the short tube, approximately ninety-five percent of the measured data were within ±
3% of the model's prediction (the model predicted the results with a standard deviation of
2.05%). The maximum difference between the measured data and the model's prediction was
within ±10%. For the pure binary mixture (AZ20) with single phase flow at the inlet of the
short tube, the predicted mass flowrate was within ±2,6% of the measured flow rates, and
t
ninety-five percent of the experimental data were within ±2% of the model's prediction (the
59
-------
model predicted the results with a standard deviation of 3.6%). We hypothesize that the
accuracy of the model for the ternary mixture (AC9000) was lower than the binary mixture
(AZ20), due to composition change in the ternary mixture as it vaporized. The small
difference between the model's prediction and experimental data could also be attributable to
uncertainties in measurements such as mass flowrate.
The goodness of it of the current model can be explored further by breaking the
amount of error into groups based upon length and diameter. Tables 6.6 and 6.7 show the
agreement of the model to ill of the experimental data for the various lengths and diameters of
short tubes.
Table 6.6: Pure Single Phase Model Comparison Based Upon Short Tube Length
L = 0.5 in (12.7 mm)
L = 0.75 in (19.05 mm)
L= 1.0 in (25.4 mm)
Pdiff
Ternary
Binary
Ternary
Binary
Ternary
Binary
Mean
2.94
1.42
2.49
1.50
4.86
7.34
Standard
Deviation
2.92
0.98
1.79
1.57
2.78
5.82
Maximum
18.15
4.08
7.65
6.47
10.30
22.70
* All values ire abtolute value percent differences between the model and experimental data.
Table 6.7: Pure Single Phase Model Comparison Based Upon Short Tube Diameter
Diameter =>
0.0432 in
(1.09 mm)
0.0528 in
(1.34 mm)
0.0674 in
(1.71 mm)
0.0763 in
(1.94 mm)
Pd®
Ternary
Binary
Ternary
Binary
Ternary
Binary
Ternary
Binary
Mean
2.78
4.20
3.59
2.29
2.73
2.54
3.02
1.33
Standard
Deviation
2.45
6.16
2.24
2.30
2.83
2.15
4.04
1.32
Maximum
10.30
22.70
11.95
9.39
16.15
7.65
18.15
4.73
* All value* are abeoiute value percent difference! between the model and experimental data.
60
-------
Table 6.6 shows that the short tubes with lengths of 1.0 in (25.4 mm) produced the
highest absolute value percent difference for mass flowrate when compared to the model.
These larger deviations from the model were generally caused by one short tube which had a
length of 1.0 in (25.4 mm) and diameter of 0.0431 in (1.09 mm). The maximum deviation of
22% occurred with the binary refrigerant mixture and averaged 17.6% for this short tube.
Close examination of this orifice showed no rough internal features or obvious geometric
irregularities. This same orifice was modeled well for the ternary refrigerant mixture. It was
hypothesized that flow conditions within the orifice had changed due to the higher operating
pressures of the binary refrigerant mixture and the large length to diameter ratio (23:1) of this
orifice.
For two-phase flow at the inlet of the short tube, the mass flow model did not predict
flowrate as well. For the ternary refrigerant mixture the model predicted flowrate to within
±15% for all pure refrigerants and oil/refrigerant mixtures. Two-phase conditions for the
binary refrigerant mixture did not show the same rapid decrease in flowrate as seen with the
ternaiy refrigerant mixture. This would be expected since the binary refrigerant mixture
operates at pressures which averaged 40% higher than those seen by the ternary refrigerant
mixture. The limited range of two-phase data prevented the development of a good fit for all
flow conditions and geometries. The absolute value percent difference for the pure case
averaged 10% with a standard deviation of 7%. This also applied to the oil/refrigerant
mixtures with an average absolute value percent difference of 9%. This lack, of good fit could
possibly be due to the uncertainty in measuring quality (±20% is the uncertainty for quality
calculations).
For both refrigerants (AC9000 and AZ20) with oil (RL32S POE), the model was a
t
better fit due to the limited geometries tested. With the ternary refrigerant mixture only 0.5 in
61
-------
(12.7 mm) orifices with diameters of0,0528 in (1.34 mm) and 0.0676 in (1.72 mm) were
tested. This limited range of experimental data was much easier to fit. Approximately ninety-
five percent of the single phase data were within ±2% of the model's prediction (the
oil/refrigerant models for AC9000 and AZ20 were fit the experimental results with a standard
deviation of 1.3% and 2.7%, respectively). Due to the limited data range for oil
concentration, the application of the model to higher oil concentrations should be done with
caution. Because oil did not have any significant effect on flow rate in the low oil
concentration region (less than 2%), the use of the pure refrigerant flow model is strongly
recommended for oil concentrations ranging from 0% to 2%. The maximum error occurred
from using the pure refrigerant model in the low oil concentration range should be less than ±
5% of the measured mass flow.
A complete summary of the model's goodness of fit can be summarized by the use of a
% (Chi Squared) calculation using the following equation:
X2 ='
Pr edicted - Measured
Error in Measured
N-n-1
(6.12)
where
N = Number of measurements
n = Number of adjustable coefficients
Error in Measured = 95% Confidence Interval on the measurement
The Chi Squared parameter given by Equation 6.12 is calculated for the various
models in Table 6,8 below.
62
-------
Table 6.8: Chi Squared Values for Semi-Empirical Models
Chi Squared Values
State
R32/125/134a
R32/125
Pure
1.1% Oil
Pure
2.2% Oil
Single-Phase
781
140
425
276
Two-Phase
3020
6514
760
243
63
-------
CHAPTER VII
SUMMARY AND RECOMMENDATIONS
To develop an acceptable flow model, an experimental investigation was performed.
The refrigerants investigated were those considered R22 replacements: R32/125/134a
(23 %/2 5 %/S 2%) and R32/125 (50%/50%). A series of tests for both refrigerants were
performed to generate data at varying operating conditions with twelve short tubes. The tests
included both single and two-phase flow conditions at the inlet of the short tube with different
oil concentrations Experimental data were presented as a function of major operating
parameters and short tube diameter. Based on test results and analysis, a mass flow model
was developed.
Short tube orifices of length 0.5 in (12.70 mm) to 1.0 in (25.4 mm) and diameters
ranging from 0.0431 in (1.09 mm) to 0.0763 in (1.94 mm) were tested for R32/125/134a
(23%/25%/52%) and R32/125 (50%/50%) at selected testing conditions found in heat pump
or air-conditioner applications. The general trends observed in both refrigerants were
consistent with the previous results for R22 (Kim and O'Neal, 1993a; Aaron and Domanski,
1990). At the same condensing temperature conditions, the mass flowrate of the ternary
mixture varied by approximately ±5% as compared to R22 while the binary refrigerant
mixture flowrate averaged 15% higher than that for R22 due to its higher operating pressures
(Table 7.1). The maximum percent difference in Table 7.1 occurred at high levels of
subcooling and large qualities. Generally, flow trends of both refrigerants were also quite
similar to each other even though mass flow rate for the binary mixture (AZ20) was
approximately 6 to 15% higher than that for the ternary mixture (AC9000). The test results
for both refrigerants showed that the mass flow rate was strongly dependent on upstream
conditions, but slightly dependent on downstream conditions.
64
-------
Table 7.1: Comparison of the Mass Flowrate for a Short Tube with L=0.5 in (12.7 mm) and D=0.0528 in (1.34 mm).
Sat. Liq.
Temp., °F (°C)
Subcooling /
Quality °F (°C)
Refri
gerant Flow, lb/h (kg/h)
% Differences
R22
R32/125/134a
(23%/25%/52%)
R3 2/125
(50%/50%)
R32/125/134a
(23%/25%/52
%)
R3 2/125
(50%/50%)
95 (35)
P
Sat Liq-
R22 : 196 psia
(1351 kPa)
Ternary: 221 psia
(1524 kPa)
Binary: 309 psia
(2130 kPa)
20(11.1)
259(117)
264 (120)
304 (138)
1.9
17.4
10 (5.6)
224 (102)
225 (102)
249(113)
0.4
11.2
5 (2.8)
211(96)
211 (96)
225 (102)
0.0
6.6
0
201 (91)
210(95)
214(97)
4.5
6.5
5%
138(63)
152 (69)
154 (70)
10.1
11.6
110(43.3)
P
Sal Liq'
R22 :241 psia
(1662 kPa)
Ternary: 271 psia
(1868 kPa)
Binary: 379 psia
(2613 kPa)
20(11.1)
281(127)
289(131)
325 (147)
2.9
15.7
10 (5.6)
242(110)
247(112)
268 (122)
2.1
10.7
5 (2.8)
226(103)
230 (104)
245(111)
1.8
8.4
0
212(96)
225 (102)
234(106)
6.1
10.4
5%
157(71)
170 (77)
169(77)
8.3
7.6
* Percent difference = (Refrigerant Mixtures - R22)/R22.
-------
The major factor affecting the flow rate was upstream conditions. For both
subcooled liquid and two-phase flow entering a short tube, the mass flow rate was directly
proportional to upstream pressure. The increase in mass flowrate with upstream pressure was
accelerated for high levels of upstream subcooling. The refrigerant flow rate increased in a
polynomial fashion with increases in upstream subcooling. The mass flow continued dropping
inside the saturation region as the quality increased.
The mass flow rate was extremely sensitive to changes in short tube diameter. The
binary mixture (AZ20) showed more effects of short tube diameter on flowrate than the
ternary mixture (AC9000). While the ternary refrigerant mixture mass flowrate in the
subcooled region varied approximately with the square of the orifice diameter, the binary
refrigerant mixture mass flowrate tended to vary more closely with diameter raised to the 2.6.
The effects of diameter varied as a function of upstream subcooling and quality.
The effects of oil on the flow through short tubes were studied by comparing test
results for oil/refrigerant mixtures with pure refrigerants (mass flow ratio mM). The presence
of oil below a concentration of approximately 2% would appear to only slightly affect the
mass flowrate (less than 5%). For both refrigerants at high levels of subcooling (beyond 10°F
(5.6°C)), the addition of oil varied flowrate from the pure case by ±5%. As subcooling
decreased, the decrease in mass flow as compared to the pure case followed a linear trend.
To predict the mass flow rate, the semi-empirical models for both single and two-
phase flow at the inlet of the short tubes were developed by empirically correcting the
modified orifice equation as a function of normalized forms of operating conditions. Due to
the limited range of oil concentrations tested, new coefficients were calculated for each oil
concentration tested. It was found that the semi-empirical flow model estimates were in good
agreement with laboratory results for both single and two-phase flow entering the short tubes.
66
-------
The tests for the effects of oil concentration were performed over a limited range of
test conditions and short tube diameters with one lubricant: RL 32S POE. Oils of higher
viscosity could produce different results from what was seen here. Also the miscibility of the
oil and refrigerant were not factored into model development. Although this oil was reported
to be miscible with the refrigerants under the test conditions, other oils may not show this
same behavior. Further study would be required to characterize the effects of oil
concentration with short tube geometry and test conditions.
It was earlier noted that the limitations on the application of the semi-empirical flow
model were imposed by the range of the experimental data. Therefore, a more
comprehensive semi-empirical model may need to be developed to obtain wider applicability.
67
-------
REFERENCES
Aaron, A.A., and Domanski, P.A. 1990. "Experimentation, analysis, and correlation of
refrigerant-22 flow through short tube restrictors." ASHRAE Transactions, Vol. 96,
Part 1, pp. 729-742.
ASHRAE. 1984. ANSI/ASHRAE Standard 41.4-1984, Standard methodfor measurement of
proportion of oil in liquid refrigerant. Atlanta; American Society of Heating,
Refrigerating, and Air-Conditioning Engineers, Inc.
ASME. 1971. Fluid meters - their theory and application, sixth edition. New York: The
American Society of Mechanical Engineers, Inc.
Chisholm, D, 1967. "Flow of compressible two-phase mixtures through throttling devices."
Chemical and Process Engineering, Vol. 48, pp. 342-350.
Corr, Stuart; Murphy, F. Thomas, and Wilkinson, Stuart. 1994. "Composition shifts of
zeotropic HFC refrigerants in service", ASHRAE Transactions, Vol 100, Pt.2.
Davies, D., and Daniels, T.C. 1973. "Single and two-phase flow of dichlorodifluoromethane,
(R-12), through sharp-edged orifice." ASHRAE Transactions, Vol. 79, Part 1, pp.
109-123.
Kim, Y., 1993. "Two-phase flow of HCFC-22 and HFC-134a through short tube orifices."
Ph.D. Dissertation, Texas A&M University, Texas.
Kim, Y. and O'Neal, D.L., 1993a. "Two-phase flow of refrigerant-22 through short tube
orifices." ASHRAE Transactions, Vol. 100, Part 1.
Kim, Y. and O'Neal, D.L., 1993b. "An experimental study of two-phase flow of HFC-134a
through short tube orifices." Heat Pump and Refrigeration System Design, Analysis,
and Applications, AES Vol 29, ASME Winter Annual Meeting New Orleans.
Kim, Y. and O'Neal, D.L., 1994a. "A semi-empirical model of two-phase flow of refrigerant-
134a through short tube orifices." Accepted for publication in Experimental Thermal
and Fluid Science, Vol 9, pp. 426-435.
Kim, Y. and O'Neal, D.L., 1994b. "The effect of oil on the two-phase critical flow of
refrigerant 134a through short tube orifices." International Journal of Heat and Mass
Transfer, Vol. 37, No. 9, pp. 1377-86.
Kline, S.J., and McClintock, F.A. 1953. "Describing uncertainties in single sample
experiments." Mechanical Engineering, Vol. 75, pp. 3-8.
68
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Krakow, K.I., and Lin, S. 1988, "Refrigerant flow through orifices." ASHRAE Transactions,
Vol. 94, Part 1, pp. 484-506.
Langley, B. 1994, Refrigerant management: the recovery, recycling, and reclaiming of
CFC's, Delmar, Albany, NY.
Mei, V.C, 1982. "Short tube refrigerant restrietors," ASHRAE Transactions, Vol. 88, Part 2,
pp. 157-168.
Pasqua, P.F. 1953. "Metastable flow of Freon-12." Refri. Eng., Vol. 61, pp. 1O84A-1088.
69
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APPENDIX A
MODEL COMPARISON WITH EXPERIMENTAL DATA
The semi-empirical flow model was developed to predict the mass flowrate through
short tubes with a given sets of conditions. The flow model was formed to cover both single
and two-phase flow at the inlet of the short tube with consideration for the effects of oil
concentration. This appendix presents the experimental data with the predicted mass flowrate
using the mass flow model developed in chapter six. It consists of four sections for each
refrigerant either with or without oil:
Page
A.l. Pure R32/125/134 (23%/25%/52%) (AC9000) 71
A.2. Pure R32/125 (50%/50%) (AZ20) 74
A.3. Mixtures of oil and R32/125/134a (23%/25%/52%) 77
A.4. Mixtures of oil and R32/125 (50%/50%), 78
The variables used in each column of the table are defined as:
L = short tube length (inch)
D = short tube diameter (inch)
Pup - upstream (condensing) pressure (psia)
Pdowrt - downstream (evaporating ) pressure (psia)
Tsub = upstream subcooling (°F)or quality (%)
(negative value indicates quality)
Mact = measured mass flowrate (Ib/min)
Mcalc = predicted flowrate using the mass flow model (Ib/min)
(Mcalc - Mact) /Mact - percent difference between the predicted and
measured mass flowrate (%)
70
-------
AI. Pure R32/125/134» (23%/ 25%/ S2%\ bv mass
PUP
PDOWN
TSUB
L
D
MACT
MCALC
%D!FF
221.57
77.94
20.205
0.5
0.0432
3.123
2.9908
-4.2336
221,41
92.05
19.958
0.5
0.0432
3.098
2.9643
•4.3142
220.22
91.89
9.811
0.5
0.0432
2.478
2.4768
-0.0486
220.81
91.87
4.792
0.5
0.0432
2.292
2.2944
0.1039
221.04
94.04
0.469
0.5
0.0432
2.186
2.22
1.5541
218.71
93.26
-0.275
0.5
0.0432
2.157
1.9547
-9.3783
221.44
94.01
-0.396
0.5
0.0432
2.175
2.0459
-5.934
222.02
93.02
-0.981
0.5
0.0432
1.986
1.7773
10.507
220.85
94.35
-3.063
0.5
0.0432
1.696
1.9901
17.3409
271.45
110.32
19.971
0.5
0.0432
3.261
3.1365
-3.8181
271.86
93.39
19.909
0.5
0.0432
3.3
3.1524
-4.4721
270.73
78.73
19.732
0.5
0.0432
3.253
3.1549
-3.0163
271.4
78.93
10.369
0.5
0.0432
2.688
2.6856
-0.091
271.21
111.81
10,188
0.5
0.0432
2.65
2.6303
-0.7451
271.86
93.29
10.149
0.5
0.0432
2.683
2.6564
-0.9926
271.35
78.58
9.497
0.5
0.0432
2.631
2.6471
0.6106
269.89
94.4
3.945
0.5
0.0432
2.421
2.4105
-0.4348
271.22
110.59
2.063
0.5
0.0432
2.345
2.3413
-0.1575
269.63
110.33
1.305
0.5
0.0432
2.291
2.3272
1.5802
271.21
80.29
1.105
0.5
0.0432
2.292
2.3822
3.9345
270.67
110.77
0.649
0.5
0.0432
2*227
2.325
4.4022
272.24
93.86
-0.131
0.5
0.0432
2.253
2.2951
1.8686
272.05
93.24
-0.227
0.5
0.0432
2.182
2.1456
-1.6688
271.23
92.78
-1.22
0.5
0.0432
2.008
2.0729
3.2338
272.18
92.15
-4.1
0.5
0.0432
1.894
2.1613
14.112
328.46
83.37
19.969
0.5
0.0432
3.507
3.3286
-5.0862
328.63
82.86
9.921
0.5
0.0432
2.866
2.7911
-2.6135
328.22
92.08
4.435
0.5
0.0432
2.66
2.5628
•3.6529
329.21
92.89
2.422
0.5
0.0432
2.544
2.5068
-1.4622
327.83
94.88
1.825
0.5
0.0432
2.525
2.4885
-1.446
328.97
92.89
1.425
0.5
0.0432
2.517
2.4885
-1.1315
327.23
93.97
-0.072
0.5
0.0432
2.404
2.4431
1.6261
329.18
92.92
-4.733
0.5
0.0432
2.087
2.3885
14.4474
221.8
93.15
20.544
0.5
0.0528
4.369
4.5456
4.0418
221.78
92.4
10.376
0.5
0.0528
3.651
3.8521
5.509
221.59
92.2
4.998
0.5
0.0528
3.522
3.5738
1.4717
221.23
94.02
1.901
0.5
0.0528
3.424
3.4733
1.4412
220.89
93.6
-1.721
0.5
0.0528
2.698
3.1043
15.0608
270.92
92.62
20.38
0.5
0.0528
4.704
4.8269
2.6117
271.43
93.15
20.352
0.5
0.0528
4.641
4.8258
3.9818
271.21
93.35
20.097
0.5
0.0528
4.684
4.8045
2.5723
271.17
110.43
19.834
0.5
0.0528
4.603
4.7573
3.3513
270.68
93.89
19.562
0.5
0.0528
4.575
4.7601
4.0468
272.06
94.26
10.199
0.5
0.0528
3.878
4.0948
5.5916
270.6
110.85
9.854
0.5
0.0528
3.852
4.0323
4.6811
271.46
94.28
9.849
0.5
0.0528
3.86
4.0699
5.4389
271.61
111.8
5.042
0.5
0.0528
3.679 *
3.7673
2.3991
271.2
94.96
4.969
0.5
0.0528
3.62
3.8018
5.0209
271.58
110.61
4.769
0.5
0.0528
3.665
3.7578
2.531
271.6
95.13
2.086
0.5
0.0528
3.552
3.7044
4.2905
271.83
94
1.682
0.5
0.0528
3.577
3.7001
3.4423
71
-------
270.73
112.08
1.568
0.5
0.0528
3.519
3.6487
3.6858
270.87
94.15
1.305
0.5
0.0528
3.522
3.6912
4.8042
271.05
94.27
0.955
0.5
0.0528
3.501
3.6884
5.3531
271.04
92.09
-2.895
0.5
0.0528
2.901
3.2484
11.9765
270.28
110.55
-3.077
0.5
0.0528
2.851
3.1719
11.2563
270.35
110.92
-3.262
0.5
0.0528
2.853
3.154
10.5486
327.54
92.9
20.004
0.5
0.0528
4.923
5.0678
2.9413
329.1
91.24
9.793
0.5
0.0528
4.179
4.3058
3.0353
329.81
93.25
5.005
0.5
0.0528
3.925
4.0261
2.5766
330.2
95.4
4.079
0.5
0.0528
3.89
3.9803
2.3223
329.94
96.37
3.249
0.5
0.0528
3.872
3.9446
1.8744
330.94
94.3
-0.396
0.5
0.0528
3.424
4.2022
22.7274
222.07
93.49
19.675
0.5
0.0531
4.705
4.5367
-3.5767
221.06
93.09
9.907
0,5
0.0531
3.837
3,8659
0.7528
220.89
93.79
4.666
0.5
0.0531
3.502
3.5984
2.7532
220.22
94.06
0.058
0.5
0.0531
3.266
3,5179
7.7137
220.6
94.4
-0.129
0.5
0.0531
3.248
3.2435
-0.1383
220.17
94.86
-3.691
0.5
0.0531
2.598
2.7666
6.4903
271.35
111.84
20.297
0.5
0.0531
5.043
4.8499
-3.8297
271.07
78.32
20.188
0.5
0.0531
5.098
4.8922
-4.0371
271.56
93.87
20.172
0.5
0.0531
5.078
4.8692
-4.1127
270.32
110.39
19.992
0.5
0.0531
4.982
4.8228
-3.1955
269.6
78.51
19.886
0.5
0.0531
5.045
4.8602
-3.6633
271.56
94.28
19.652
0.5
0.0531
4.994
4.828
-3.3246
270.66
77.79
10.161
0.5
0.0531
4.172
4.1701
-0.045
271.07
111.59
8.878
0.5
0.0531
4.075
4.0842
0.2246
270.9
93.64
9.863
0.5
0.0531
4.155
4.1203
-0.8362
271.53
77.99
5.179
0.5
0.0531
3.823
3.9004
2.0257
271.42
94.25
4.81
0.5
0.0531
3.765
3.845
2.1258
270.73
111.02
4.542
0.5
0.0531
3.728
3.7908
1,6843
272.69
78.51
2,079
0.5
0.0531
3.597
3.7975
5.5752
271.52
111.6
1.17
0.5
0.0531
3.568
3.6946
3.5472
270.32
112.17
0.896
0.5
0.0531
3.532
3.6873
4.3965
270.52
78.99
0.754
0.5
0.0531
3.48
3.7726
8.4089
269.93
111.86
0.474
0.5
0.0531
3.543
3.6881
4.0942
271.84
92.S2
0.453
0.5
0.0531
3.558
3.746
5,2833
270.58
112.41
0.155
0.5
0.0531
3.302
3.6964
11.8451
272.23
77,58
-0.634
0.5
0.0531
3.208
3.7034
15.442
270.77
93.6
-2.303
0.5
0.0531
3.06
3.2603
6.5447
270.86
111.25
-2.743
0.5
0.0531
3.009
3.2116
6.7326
329.43
92.7
19.979
0.5
0.0531
5.426
5.1349
-5.3652
329.74
93.22
10.084
0.5
0.0531
4.462
4.3767
-1.9109
330.29
93,7
5.638
0.5
0.0531
4.112
4.1086
-0.0831
330.21
93.41
1.977
0.5
0.0531
3.917
3.9657
1.2423
330.66
94.48
0.557
0.5
0.0531
3.771
3.9479
4.6906
329.4
94.04
-1.72
0.5
0.0531
3.4
3.7315
9.7512
222.06
94.27
20.632
0.5
0.0676
7.491
7,6362
1.9384
221,49
91.26
10.381
0.5
0.0676
6.579
6.5714
-0.1157
222.12
94.98
4.796
0.5
0.0676
6.318
6.1516
-2.6341
221.78
93.57
1.886
0.5
0.0676
6.127
6.0375
-1.46
222.4
94.75
-1.573
0,5
0.0676
4.59
4.7675
3.8665
220.88
94.32
-1.972
0.5
0.0676
4.494
4.565
1.5803
272.31
92.98
20.238
0.5
0.0676
7.91
8.1078
2.5009
271.12
93.22
19.974
0.5
0.0676
7.874
8.0642
2.4154
270.31
111.83
19.856
0.5
0.0676
7.857
7.9967
1.7785
270.48
91.87
19.61
0,5
0.0676
7.821
8.0181
. 2.5195
72
-------
269.99
110.55
19.466
0.5
0.0676
7.813
7.9488
1.7376
270.91
111.71
9.669
0.5
0.0676
6.806
6.8878
1.2015
269.48
94.03
9.4
0.5
0.0676
6.771
6.9092
2.0409
272.18
94.4
5.407
0.5
0.0676
6.552
6.6147
0.9568
270.74
111.65
2.876
0.5
0.0676
6.481
6.4047
-1.178
271.48
112.65
2.67
0.5
0.0676
6.406
6.3976
-0.1311
271.83
96.16
2.562
0.5
0.0676
6.361
6.4592
1.5438
272.68
112.03
1.57
0.5
0.0676
6.411
6.3791
-0.498
271.33
97.82
1.518
0.5
0.0676
6.326
6.423
1.5341
271.59
98.74
1.294
0.5
0.0676
6.247
6.419
2.754
270.38
111.58
1.061
0.5
0.0676
6.355
6.3594
0.0685
270.22
113.19
0.596
0.5
0.0676
6.355
6.3551
0,0013
270.88
93.93
-0.179
0.5
0.0676
5.321
6.4219
20.689
271.02
112.58
-1.844
0.5
0.0676
4.982
5.1001
2.3709
329.54
98.48
20.036
0.5
0.0676
8.394
8.5415
1.757
329.93
98.72
19.961
0.5
0.0676
8.398
8.5333
1.6112
329.83
100.26
9.968
0.5
0.0676
7.282
7.3769
1.3032
330.39
102.75
5.109
0.5
0.0676
6.92
6.9554
0.5109
328.22
103.09
4.266
0.5
0.0676
6.837
6.8868
0.7287
329.69
105.19
2.051
0.5
0.0676
5.84
6.7834
16.1549
329.81
107.54
2.006
0.5
0.0676
6.687
6.7729
1.2852
327.38
106.31
1.918
0.5
0.0676
6.618
6.7611
2.1623
330.96
104.66
1.838
0.5
0.0676
6.508
6.7867
4.2819
220.93
92.3
20.029
0.5
0.0763
9.79
9.7529
-0.3785
220.54
94.79
9.785
0.5
0.0763
9.083
8.4566
-6.8966
221.07
99.66
4.53
0.5
0.0763
8.759
7.9944
-8.7289
221.35
101.46
1.394
0.5
0.0763
7.882
7.8712
-0.1365
222.09
101.85
1.354
0.5
0.0763
8.024
7.8786
-1.8126
222.07
100.89
1.333
0.5
0.0763
7.854
7.8817
0.3532
222.13
102.83
1.212
0.5
0.0763
8.219
7.874
-4.1978
221.15
93.8
-0.275
0.5
0.0763
6.362
7.212
13.3612
271.07
102.39
19.673
0.5
0.0763
10.357
10.3402
-0.1618
270.62
102.44
19.054
0.5
0.0763
10.256
10.2428
-0.129
270.29
105.5
9.64
0.5
0.0763
9.099
8.9903
-1.1946
272.16
109.72
5.29
0.5
0.0763
8.876
O C7CO
0.3 / 00
-3.3824
271.1
109.38
4.786
0.5
0.0763
8.852
8.5282
-3.6583
271.2
106.44
1.87
0.5
0.0763
7.108
8.3979
18.1466
272.53
114.18
1.591
0.5
0.0763
8.3
8.3678
0.8174
271.35
112.51
1.452
0.5
0.0763
8.086
8.3615
3.4068
272.14
114.67
1.326
0.5
0.0763
8.442
8.3584
-0.9901
329
116.27
19.446
0.5
0.0763
11.072
10.88
-1.7344
329.34
118.49
10.136
0.5
0.0763
9.666
9.5521
-1.1782
327.86
118.4
9.281
0.5
0.0763
9.596
9.4381
-1.6452
329.48
126.24
5.112
0.5
0.0763
9.185
8.9907
-2.1153
330.53
127.21
2.405
0.5
0.0763
7.666
8.8192
15.0428
329.91
134.97
2.048
0.5
0.0763
8.848
8.7603
-0.9907
330.01
132.39
2.021
0.5
0.0763
8.903
8.7737
-1.4518
328.56
131.48
-0.363
0.5
0.0763
7.231
8,2044
13.4609
271.88
94.79
20.135
0.75
0.0435
3.148
3.0789
-2.1959
270.45
93.7
10.054
0.75
0.0435
2.496
2.4921
-0.157
271.45
93.88
2.412
0.75
0.0435
2.194
2.1535
-1.8447
270.89
93.91
1.435
0.75
0.0435
2.18
2.1284
-2.369
270.12
94.19
19.279
0.75
0.0528
4,603
4.4558
-3.1974
270.89
92.46
19.26
0.75
0.0528
4.539
4.4606
-1.7277
270.94
92.51
11,151
0.75
0.0528
3.838
3.777
-1.5903
269.99
92.97
10.464
0.75
0.0528
3.745
3.7185
-0.7078
73
-------
271.16
92.68
9.604
0.75
0.0528
3.7
3.6569
-1.1651
270.93
93.25
2.401
0.75
0.0528
3.264
3.206
-1,7784
271.9
93.55
0.269
0,75
0.0528
3.206
3.1652
-1.2734
271.25
94.23
20.182
0.75
0.0676
7.697
7.4787
-2.8384
271.07
93.15
10.31
0.75
0.0676
6.322
6.1591
-2.5775
270.13
92.75
9.447
0.75
0.0676
6.204
6.0506
-2.4728
270.42
95.38
2.08
0.75
0.0676
5.649
5.3521
-5.2562
271.58
96.29
1.354
0.75
0.0676
5.591
5,3231
-4.7908
271.67
96.61
1.198
0.75
0.0676
5.567
5.318
-4.4735
270
97.41
1.103
0.75
0.0676
5.557
5.3028
-4.5746
271.18
100.98
20.084
0.75
0.0762
9.656
9.5063
-1.5498
270.25
97.03
9.5
0.75
0.0762
7.791
7.7567
-0.4406
270.79
97.72
2.667
0.75
0.0762
6.453
6.9465
7.6468
271.24
103.31
2.273
0.75
0.0762
7.092
6.8889
-2.8631
272.02
105.77
2.145
0.75
0,0762
7.024
6.8725
-2.1569
272.02
106.76
2.052
0.75
0.0762
6.856
6.8609
0.0708
271.93
93.07
20.35
1
0.0431
2.883
3.0446
5.6057
270.68
92.33
19.826
1
0.0431
2.816
3.0103
6.8992
272.01
92.66
9.961
1
0.0431
2.215
2.4432
10.3016
271.41
93.99
1.711
1
0.0431
1.942
2.0759
6,8961
271.62
93.31
20.105
1
0.0535
4.503
4.6462
3.1797
271.5
93.21
20.026
1
0.0528
4.517
4.5188
0.0399
271.25
94.01
19.543
1
0.0535
4.996
4.5914
-8.0987
271.07
92.51
10.165
1
0.0535
3.529
3.7636
6.6491
270.38
93.55
9.887
1
0.0535
4.002
3.7357
-6.6538
271.76
93.66
2.512
1
0.0535
3.42
3.2323
-5.4893
271.54
94.79
2.05
1
0.0535
2.96
3.2086
8.3985
269.74
94.15
1.258
1
0.0535
3.332
3.1784
-4.6108
271.38
94.53
0.962
1
0.0535
3.293
3.1746
-3.5941
271.18
95.3
20.574
1
0.0676
8.132
7.4473
-8.4203
271.11
94.14
9.789
1
0.0676
6.288
5.9392
-5.5468
271.08
94.35
2.257
1
0.0676
5.069
5.1455
1.5085
271.32
96.32
2.111
1
0.0676
5.47
5.1279
-6.2542
270.38
97.07
1.065
1
0.0676
5.297
5.0708
-4.2699
270.93
99.22
19.462
1
0.0762
9.472
9.2277
-2.5792
270.93
99.22
19.462
1
0.0762
9.472
9.2277
-2.5792
271.09
95.29
10.231
1
0.0762
7.654
7.613
-0.5359
270.93
98.76
2.867
1
0.0762
6.69
6.5813
-1.6244
271.56
101.22
2.414
1
0.0762
6.666
6.5292
-2.0524
A2: Pure R32/125 (50%/ 50%) bv mass
Pup
Pdown
- Tsub
L
D
Mact
Mcalc
% Diff
310.44
132.02
20.434
0.5
0.0432
3.444
3.358635
-2.47867
309.36
134.77
10.062
0.5
0.0432
2.668
2.709058
1.538913
309.78
131.99
5.629
0.5
0.0432
2.476
2.469837
-0.24892
309.73
135.82
2.246
0.5
0.0432
2,384
2.342438
-1.74338
309.65
129.13
-1.735
0.5
0.0432
2.318
2.112346
-8.87205
379.72
155.77
20.133
0.5
0.0432
3.63
3.587644
-1.16683
378.83
110.02
19.91
0.5
0.0432
3.644
3.530904
-3.10363
380.39
133.36
19.59
0.5
0.0432
3.564
3.534278
-0.83395
379.31
133.27
10.17
0.5
0.0432
2.914
2.928121
0.484588
74
-------
378.
379,
379,
380.
379,
37)
379,
460,
460,
461,
460,
460,
309,
309.
310,
310,
309,
308
380,
379,
37!
379.
379,
379,
379.
379.
379,
38!
379.
461.
460,
461.
4
461.
461.
309.
310.
310.
309.
309.
309.
379.
379.
379.
379.
379.
380.
460.
460.
460.
461.
156.22
9.962
0.5
0.0432
2.916
2.943303
111.19
9.911
0.5
0.0432
2.949
2.886071
132
5.348
0.5
0.0432
2.7
2.668467
134.55
1.559
0.5
0.0432
2.544
2.538887
157.89
1.185
0.5
0.0432
2.559
2.565479
112.71
1.01
0.5
0.0432
2.533
2.494349
133.87
-5.692
0.5
0.0432
2.055
1.986915
132.94
20.162
0.5
0.0432
3.889
3.789406
133.47
9.756
0.5
0.0432
3.221
3.110816
133
5.227
0.5
0.0432
2.929
2.869756
131.72
2.272
0.5
0.0432
2.785
2.754733
131.73
-2.249
0.5
0.0432
2.812
2.482679
133.67
20.067
0.5
0.0528
4.959
5.070886
132.4
9.804
0.5
0.0528
4.075
4.123073
134.07
4.643
0.5
0.0528
3.731
3.732589
134
1.364
0.5
0.0528
3.61
3.567817
134.24
0.864
0.5
0.0528
3.542
3.553918
133.39
-3.714
0.5
0.0528
2.941
2.956285
115.71
20.108
0.5
0.0528
5.333
5.411588
156.88
20.008
0.5
0.0528
5.306
5.451177
132.48
19.776
0.5
0.0528
5.313
5.396154
156.11
10.123
0.5
0.0528
4.434
4.520349
117.78
9.888
0.5
0.0528
4.45
4.434929
132.3
9.664
0.5
0.0528
4.424
4.43707
133.69
4.662
0.5
0.0528
4.139
4.05335
123.77
1.879
0.5
0.0528
3.977
3.884434
133.01
1.755
0.5
0.0528
4.047
3.899814
156.16
1.735
0.5
0.0528
3.982
3.950208
131.97
-0.205
0.5
0.0528
3.778
3.684507
132.28
20.249
0.5
0.0528
5.643
5.7826
134.1
9.406
0.5
0.0528
4.722
4.734656
138.35
5.326
0.5
0.0528
. 4.51
4.422825
139.25
4.712
0.5
0.0528
4.461
4.378474
146.99
1.932
0.5
0.0528
4.319
4.251782
142.8
-1.111
0.5
0.0528
4.258
3.959133
132.68
20.184
0.5
0.0674
8.416
8.610179
133.32
10.364
0.5
0.0674
7.154
7.209345
133.46
4.624
0.5
0.0674
6.682
6.518471
135.01
1.513
0.5
0.0674
6.453
6.267879
133.11
1.468
0.5
0.0674
6.445
6.261112
132.87
-1.52
0.5
0.0674
5.426
5.537805
140.12 .
19.742
0.5
0.0674
8.952
9.168242
144.36
10.078
0.5
0.0674
7.753
7.76593
147.46
4.961
0.5
0.0674
7.317
7.152936
153.16
2.037
0.5
0.0674
7.083
6.920342
155.32
1.398
0.5
0.0674
6.998
6.894781
152.58
-0.701
0.5
0.0674
6.84,5
6.239181
149.1
19.481
0.5
0.0674
9.58
9.734323
157.32
9.907
0.5
0.0674
8.373
8.324651
155.98
4.908
0.5
0.0674
7.921
7.712995
169.8
2.026
0.5
0.0674
7.626
7il9496
-------
461.48
164.82
460.87
167.65
310.35
133.73
309.73
132.94
310.18
135.77
310.1
141.17
310.17
145.07
310.08
140
309.94
141.71
380.4
150.17
380.17
159.66
380.24
150.56
380.71
158.35
380.69
157.3
381.6
159.05
380.36
159.5
379.86
153.93
459.78
161.29
459.75
168.84
461.3
168.98
460.38
177.19
461.05
179.52
460.5
177.05
379.32
132
379.52
133.1
378.93
134.11
378.92
131.65
379.25
133.16
379.66
133.76
379.23
134.08
379.49
133.98
379.63
132
378.95
133
378.83
136.48
380.15
161.21
379.2
166.6
379.15
169.46
378.99
167.92
379.96
153.32
379.03
146.03
378.83
149.7
379.82
165.15
380.02
168.21
380.51
167.92
380.13
159.96
379.36
160.52
379.39
136.04
379.72
140.03
379.49
140.82
380.62
140.68
379.59
136.75
1.94
0.5
-1.867
0.5
20.165
0.5
10.488
0.5
5.131
0.5
1.833
0.5
1.364
0.5
-1.377
0.5
-1.943
0.5
19.969
0.5
10.116
0.5
5.231
0.5
1.594
0.5
1.569
0.5
1.38
0.5
1.313
0.5
-0.395
0.5
19.423
0.5
9.745
0.5
5.083
0.5
2.039
0.5
1.901
0.5
-0.921
0.5
20.258
0.75
9.939
0.75
1.262
0.75
-3.766
0.75
19.909
0.751
9.799
0.751
1.56
0.751
1.525
0.751
-5.512
0.751
19.679
0.751
9.713
0.751
1.666
0.751
1.543
0.751
1.406
0.751
1.373
0.751
-1.231
0.751
19.94
0.751
9.543
0.751
1.587
0.751
1.38
0.751
1.262
0.751
-0.609
0.751
-1.565
0.751
20.028
0.998
19.851
0.998
10.092
0.998
9.762
0.998
9.592
0.998
0.0674
7.57
0.0674
7.233
0.0763
11.329
0.0763
9.556
0.0763
8,876
0.0763
8.528
0.0763
8.2
0.0763
6.899
0.0763
6.742
0.0763
12.17
0.0763
10.409
0.0763
9.807
0.0763
9.474
0.0763
9.455
0.0763
9.265
0.0763
9.202
0.0763
7.977
0.0763
12.878
0.0763
11.186
0.0763
10.567
0.0763
10.099
0.0763
10.076
0.0763
9.277
0.0528
5.265
0.0528
4.183
0.0528
3.607
0.0528
3.176
0.0431
3.698
0.0431
2.893
0.0431
2.432
0.0431
2.47
0.0431
2.1
0.0676
8.591
0.0676
7.06
0.0676
6.331
0.0676
6.286
0.0676
6.239
0.0676
6.227
0.0676
5.582
0.0762
11.011
0.0762
9.04
0.0762
8.15
0.0762
8.08
0.0762
8.121
0.0762
7.492
0.0762
7.208
0.06894
9.684
0.06894
9.671
0.06894
7.783
0.06894
7.748
0.06894
7.735
7.499009
-0.93779
6.63006
-8.33596
11.36361
0.30548
9.648284
0.965719
8.869722
-0.07073
8.549576
0.253007
8.534385
4.077862
7.500221
8.71461
7.398134
9.732037
12.18455
0.119545
10.44318
0.328414
9.691262
-1.18018
9.360815
-1.19469
9.353321
-1.0754
9.358833
1.012768
9.345735
1.561998
8.662744
8.596511
12.87925
0.00971
11.14249
-0.389
10.46849
-0.93227
10.17637
0.76608
10.18054
1.037547
9.273064
-0.04243
5.271819
0.129507
4.290924
2.580067
3.735
3.548649
3.106081
-2.20148
3.458644
-6.47257
2.829579
-2.19221
2.488453
2.321246
2.488502
0.749089
1.956836
-6.81734
8.640098
0.571501
7.075445
0.218772
6.265432
-1.03567
6.271201
-0.23542
6.27571
0.588402
6.267333
0.647713
5.710685
2.305355
11.13272
1.105404
9.061369
0.236378
7.995942
-1.89028
7.998916
-1.00351
7.995304
-1.54779
7.511221
0.256551
7.161986
-0.63838
8.949701
-7.5826
8.931384
-7.64777
7.355116
-5.49767
7.314617
-5.59348
7.2(69676
-6.01583
-------
378.86
149.95
380.15
152.34
379.64
154.15
379.15
146.48
378.98
146.8
380.27
147.12
379.71
132.62
379.85
133.64
379.5
131.9
380.06
134.34
379.41
132.78
379.27
132.34
379.11
134.53
379.06
133.52
378.92
130.66
379.17
136.45
379.4
131.78
379.52
133.12
379.3
145.48
379.17
151.01
379.98
164.42
379.02
164.2
380.48
168.97
378.94
161.25
379.23
161.85
1.744
0.998
1.426
0.998
1.36
0.998
-0.047
0.998
-0.5
0.998
-0.881
0.998
20.125
1
9.833
1
4.31
1
2.121
1
-6.136
1
-8.717
1
19.798
1
9.591
1
1.798
1
1.383
1
-2.361
1
-4.028
1
19.988
1
9.693
1
1.713
1
1.661
1
1.174
1
-0.2
1
-0.69
1
0.06894
6.721
0.06894
6.693
0.06894
6.663
0.0676
6.129
0.0676
6.134
0.0676
5.911
0,0431
3.034
0.0431
2.35
0.0431
2.195
0.0431
2.03
0.0431
1.73
0.0431
1.726
0.0528
5.077
0.0528
3.978
0,0528
3.437
0.0528
3.413
0.0528
3.142
0.0528
3.047
0.0762
11.004
0.0762
8.756
0.0762
7.67
0.0762
7.664
0.0762
7.596
0.0762
7.303
0.0762
7.011
6.444114 -4.11872
6.449137 -3.64356
6.450304 -3.1822
6,065846 -1.03041
5.863994 -4.40179
5.731254 -3.04087
3.428074 12.88859
2.798861 18.10048
2.543335 15.8695
2.490787 22.69889
1.897159 9.662343
1.754912 1.675099
5.161225 1.658945
4.211765 5.876443
3.727512 8.45248
3.733632 9.394438
3.26121 3.794091
3.033776 -0.43399
10.99799 -0.05463
8.982799 2.590208
7.95563 3.723988
7.943449 3.646257
7.955277 4.729817
7.568625 3.637202
7.396483 , 5.498257
A3: 1.0% Oil and R32/125/134a (23%/ 25%/ S2%> bv mass
PUP
PDOWN
TSUB
I
D
MACT
MCALC
%DlFF
220.83
91.32
20.32
0.5
0.0528
4.372
4,3933
0.4862
221.55
92.72
9.871
0.5
0.0528
3.554
3,7013
4.1454
220.94
94.7
4.577
0.5
0.0528
3.417
3.4577
1.19
220.8
92.75
3.151
0.5
0.0528
3.41
3.4271
0.5015
220.88
93.04
2.751
0.5
0.0528
3.375
3.4195
1.3173
220.64
92.65
-3.647
0.5
0.0528
2.457
2.9048
18.2248
270.47
94.5
19.755
0.5
0.0528
4.597
4.6107
0.297
270.79
94.46
9.991
0.5
0.0528
3.86
3.9154
1.4341
271.45
95.97
4.812
0.5
0.0528
3.555
3.6495
2.6573
271.49
97.36
2.834
0.5
0.0528
3.53
3.5857
1.5778
272.2
96.29
-2.563
0.5
0.0528
2.891
3.3481
15.8095
271.12
96.38
-2.752
0.5
0.0528
2.846
3,2965
15.8286
329.58
94.23
20.414
0.5
0,0528
4.982
4.9166
-1.3119
329.12
92.42
10.114
0.5
0.0528
4.188
4.122
-1.5759
329.07
93.58
5.001
0.5
0.0528
3.91
3.828
-2.0974
329.86
95.17
3.631
0.5
0.0528
3.93T
3.7695
-4.1085
328.84
94.88
2.848
0.5
0.0528
3.706
3.7453
1.0596
329.01
92.94
-2.706
0.5
0.0528
3.153
3.6931
17.1283
220.52
92.56
19.657
0.5
0.0676
7.316
7.3588
0.5855
221.21
94.37
9.922
0.5
0.0676
6.604
6.4507
-2.3214
-------
221,76
95.61
5.804
0.5
0.0676
6.467
6.201
-4.1138
221.27
95.52
5.192
0.5
0.0676
6.447
6.1716
-4.272
220.49
98.37
2.503
0.5
0.0676
6.21
6.089
-1.9483
221.35
100.31
2.109
0.5
0.0676
6.195
6.0861
-1.7574
221.9
93.7
-2.225
0.5
0.0676
5.304
4.9459
-6.7506
270.72
100.91
20.115
0.5
0.0676
7.76
7.8627
1.3231
271.73
102.32
10.375
0.5
0.0676
6.667
6.8607
2.9055
270.6
104.9
4.638
0.5
0.0676
6.338
6.4659
2.0174
270.54
108.56
2.568
0.5
0.0676
6.223
6.3881
2.6533
270.8
105.62
-2.289
0.5
0.0676
5.976
5.3547
-10.3961
272.55
105.04
-2.291
0.5
0.0676
5.928
5.3713
-9.391
329.24
104.28
20.052
0.5
0.0676
8.263
8.2906
0.3344
329.49
106.68
10.091
0.5
0.0676
7.161
7.178
0.2377
328.42
111.54
4.926
0.5
0.0676
6.785
6.7643
-0.3047
329.45
112.37
4.879
0.5
0.0676
6.778
6.7629
-0.2233
330.16
117.72
3.103
0.5
0.0676
6.586
6.6603
1.1282
329.94
113.7
-2.803
0.5
0.0676
5.922
5.7471
-2.9539
A4: 2.15% Oil and R32/125/134a
Pup
Pdown
Tsub Length
Diameter
Mdotact
Mdotcalc
%Diff
380.62
132.32
20.226
0.5
0.0432
3.689
3,536306
-4,13918
379.34
132.79
9.78
0.5
0.0432
2.889
2.88945
0.01556
380.01
132.45
5.044
0.5
0.0432
2.673
2.632653
-1.50943
379.55
132.44
1.966
0.5
0.0432
2.588
2.492717
-3.68173
379.98
132.08
1.709
0.5
0.0432
2.541
2.483187
-22752
379.12
133.18
0.971
0.5
0.0432
2.499
2.457419
-1.66392
379.1
133.77
-2.546
0.5
0.0432
2.214
2.166751
-2.13412
379.81
132.89
-2.866
0.5
0.0432
2.217
2.174384
-1.92223
310.73
133.63
20.206
0.5
0.0528
5.02
5.087245
1.33954
309.72
134.25
19.825
0.5
0.0528
4.984
5.049347
1.311135
310.23
133.94
10.287
0.5
0.0528
4.073
4.160596
2.150645
309.74
133.49
9.868
0.5
0.0528
4.073
4.119206
1.134441
309.76
131.93
5.247
0.5
0.0528
3.734
3.710186
-0.63776
309.94
131.67
4.834
0.5
0.0528
3.709
3.675372
-0.90666
309.23
133.76
0.822
0.5
0.0528
3.461
3.385429
-2,18351
309.4
135.55
0.686
0.5
0.0528
3.444
3,385323
-1.70375
309.46
132.38
-2.18
0.5
0.0528
3.069
2.946352
*3,99636
309.67
132.64
-3.428
0.5
0.0528
2.927
2.868348
•2.00384
379.53
134.67
19.843
0.5
0.0528
5.318
5.295735
-0.41866
379.07
136.12
9.621
0.5
0.0528
4.409
4.39289
-0.3654
379.63
132.23
5.008
0.5
0.0528
4.094
4.027935
-1.61369
380.08
134.56
1.584
0.5
0.0528
3.973
3.830509
-3.58649
379.62
135.26
1.079
0.5
0.0528
3.906
3.80775
-2.51536
380.07
133.59
-1.886
0.5
0.0528
3,43.1
3.328881
-2.97637
379.97
133.38
-3.338
0.5
0.0528
3.305
3.250963
-1.63501
459.86
132.92
20.037
0.5
0.0528
4.752
5.517195
16,10259
461.61
133.84
10.602
0.5
0.0528
4.805
4.733553
-1.48694
78
-------
481.02
132.83
461.34
133.97
460.89
133.29
460.82
131.65
309.59
131.84
310.35
134.05
310.14
133.79
310.51
133.85
309.29
133.83
310.71
133.48
310.27
134.87
309.62
133.92
378.96
143.4
379.47
139.44
379.54
142.59
379.27
147.31
380.42
147.15
380.09
147.96
379.99
144.03
379.65
143.02
460.71
156.31
460.8
147.51
460.1
151.23
461.3
156.21
460.86
157.01
460.66
159.12
460.51
152.92
379.1
153.02
379.17
160.27
379.77
166.98
379.18
178.52
379.94
170.34
380.19
170.5
379.96
132.22
379.72
132.39
379.93
134.75
379.41
135.34
380.07
134.45
380.08
134.44
379.19
132.95
379.54
133.36
379.77
141.68
379.1
141.53
379.3
143.37
379.66
132.77
378.97
131,27
377.62
133.59
379.82
132.73
379.84
130.77
379.47
134.53
379.99
134.49
4.93
0.5
2.141
0.5
-1.8
0.5
-3.241
0.5
19.654
0.5
10.019
0.5
9.858
0.5
5.188
0.5
1.146
0.5
1.12
0.5
-0.445
0.5
-1.511
0.5
20.085
0.5
9.939
0.5
5.064
0.5
1.322
0.5
1,186
0.5
1.13
0.5
-1.07
0.5
-1.906
0.5
19.653
0.5
9.716
0.5
4.946
0.5
1.842
0.5
1.811
0.5
-0.2
0.5
•0.805
0.5
19.618
0.5
9.784
0.5
4.98
0.5
1.03
0.5
-0.5
0.5
-0.6
0.5
20.101
0.75
9.989
0.75
1.809
0.75
1.175
0.75
-2.491
0.75
-3.921
0.75
19.782
0.751
9.979
0.751
1.902
0.751
-0.2
0.751
-0.3
0.751
19.587
1
1.519
1
1.453
1
-0.25
1
-0.35
1
20
1
10.445
1
0.0528
4.461
0.0528
4.262
0.0528
3.693
0.0528
3.623
0.0674
8.35
0.0674
6.94
0.0674
6.947
0.0674
6.506
0.0674
6.211
0.0674
6.185
0.0674
5.389
0.0674
5.14
0.0674
9.005
0.0674
7.645
0.0674
7.184
0.0674
6.838
0.0674
6.788
0.0674
6.798
0.0674
5.726
0.0674
5.59
0.0674
9.695
0.0674
8.313
0.0674
7.882
0.0674
7.464
0.0674
7.376
0.0674
6.434
0.0674
6.248
0.0763
12.057
0.0763
10.225
0.0763
9.6
0.0763
8.952
0.0763
8.162
0.0763
8.151
0.0528
5.253
0.0528
4.13
0.0528
3.616
0.0528
3.586
0.0528
3.233
0.0528
3.16
0.0676
8.685
0.0676
7.036
0.0676
6.264
0.0676
5.919
0.0676
5.846
0.0528
5.123
0.0528
3.372
0.0528
3.296
0.0528
3.378
0.0528
3.33
0.0676
9.143
0.0676
7.244
4.353018
-2.42059
4.225008
-0.86795
3.765162
1.95402
3.656689
0.92987
8.439376
1.070372
7.101657
2.329347
7.077945
1.884916
6.491887
-0.21693
6.05701
-2.47931
6.066806
-1.91098
5.308304
-1.49742
5.213445
1.428883
8.97342
-0.35069
7.617182
-0.36387
7.102042
-1.14085
6.824261
-0.20092
6.825299
0.549479
6.824439
0.388925
5.84425
2.065146
5.710267
2.151469
9.35576
-3.49912
8.116024
-2.3695
7.705054
-2.24494
7.554937
1.21834
7.555868
2.43856
6.779874
5.375721
6,647975
6.401646
11.75769
-2.48247
10.26705
0.411217
9.723675
1.28828
9.46226
5.69995
7.988684
-2.12345
7.956423
-2.38715
5.265684
0.241457
4.31501
4.479653
3.684364
1.890598
3.648284
1.736867
3.289741
1.755071
3.23016
2.220265
8.537644
-1.69667
7.049685
0.194497
6.097859
-2.65232
5.531913
-6.53973
5.504198
-5.84676
5.251021
2.498942
3.65175
8.296271
3.6514
10.78276
3.489089
3.288607
3.451509
3.648907
8.631537
-5.59404
7.159178
-1.17092
-------
379.54 141.42 1.835 1 0.0676 6.127 6.088179 -0.6336
379.81 141.31 -0.16 1 0.0676 5.727 5.654051 -1.25807
379.47 140.07 -0.21 1 0.0676 5.713 5.688834 -0.42125
** When calculations are being made in the two-phase region, the value of SUBC
is set equal to zero.
80
-------
APPENDIX B
QUALITY ASSURANCE AND UNCERTAINTY ANALYSIS
The original quality assurance plan outlined possible test conditions for the short tube
orifice test facility. The actual test sequence and the methods of assuring data quality will be
described below. All data quality objectives were met throughout the short tube orifice tests.
All tests were designed to reveal the effects of the main operating parameter on mass
flowrate through a short tube orifice. Two R22 replacement refrigerants were tested under
the same condensing and evaporating conditions. The ternary zeotropic refrigerant, AC9000,
and the binary near-azeotropic refrigerant, AZ20, were tested to determine the mass flowrate
through short tube orifices as a function of the primary variables upstream pressure,
downstream pressure, upstream subcooling, orifice length, and orifice diameter. Tables B1
and B2 list the tests performed for the pure ternary refrigerant while Tables B4 and B5 list the
tests performed for the pure binary refrigerant. Oil and refrigerant mixture testing was done
within a limited range of the primary variables. The oil tests performed are shown in Tables
B6 and B7.
The asterisk subscripts appearing in the upper portion of a table adjacent to a diameter
and again in the lower portion of a table adjacent to a downstream pressure indicate that these
were the only orifices tested at varying downstream pressures. It was unnecessary to test all
orifices at varying downstream pressures due to the choked conditions of the tests.
Downstream pressure was shown not to affect mass flowrate as long as the flow was choked,
which was the case for all tests.
Short tube orifice length was tested at only one upstream pressure. Previous
investigations have shown that testing at other upstream pressures was unnecessary due to the
similarity of flow trends for the different lengths.
81
-------
Table Bl: Test Matrix for Pure AC9000 with Orifice Length of 0,5 in (12.7 mm)
Diameter, in (mm)
Length, in (mm)
0,0431 (1.09)
0.500(12.7)
0.0528(1.34)
0.0676(1.72)
0.0763 (1.94)
psit fkPa)
mm (fcPa)
*F °TT fCfC%\
*ip JT 1 VI
TMb °F rc>
221.06(1524)
93.65 (646)
75 (23.9)
20(11.1)
85 (29.4)
10 (5.6)
90 (32.2)
5 (2.8)
95 (35)
0(0)
95 (35)
5%
271.25 (1870)
78.37 (540) ~~
90 (32.2)
20(11.1)
93.65 (646)
100 (37.8)
10 (5.6)
111.07(765)****
105 (40.6)
5 (2.8)
110(43.3)
0(0)
110 (43.3)
5%
329J1 (2271))
93.65 (646)
105 (40.6)
20(11.1)
115(46.1)
10 (5.6)
120 (48.9)
5 (2.8)
125 (51.7)
0(0)
125 (51.7)
5%
82
-------
Table B2: Test Matrix for Pure AC9000 with Orifice Lengths of 0.75 in (19.05 mm) and 1.00
in (25.4 mm)
Diameter, in (mm)
Length, in (mm)
0.0431 (1.09)
0.750 (19.05)
1.000 (25.4)
0.0528 (1.34)
0.0676 (1.72)
0.0763 (1.94)
PB0 psia (kPa)
Pdomi psia (kPa)
Tbd °F (°C)
TMb °F (°0
271.25 (1870)
93.65 (646)
90 (32.2)
20(11.1)
100 (37.8)
10 (5.6)
105 (40.6)
5 (2.8)
110(43.3)
0(0)
110(43.3)
5%
83
-------
Table B3: Test Matrix for Pure AZ20 with Orifices of Length 0.5 in (12.7 mm)
Diameter, in (mm)
Length, in (mm)
0.0431(1,09)"*"
0.500 (12.7)
0.0528 (1.34)
0.0676 (1.72)
0.0763 (1.94)
Py„ psia (kPa)
Pdown psia (kPa)
Tub °F (°C)
T,ub °F (°C)
309.79 (2136)
132.71 (915)
75 (23.9)
20(11.1)
85 (29.4)
10 (5.6)
90 (32.2)
5 (2.8)
95 (35)
0(0)
95 (35)
5%
379.66 (2618)
111.51 (769)*""
90 (32.2)
20(11.1)
132.71 (915)
100 (37.8)
10(5.6)
156.89 (1082) ****
105 (40.6)
5(2.8)
-
110(43.3)
0(0)
110(43.3)
5%
460.66 (3176))
93.65 (646)
105 (40.6)
20(11.1)
115(46.1)
10 (5.6)
120 (48.9)
5 (2.8)
125 (51.7)
0(0)
125 (51.7)
5%
84
-------
Table B4: Test Matrix for Pure AZ20 with Orifices of Length 0.75 in (19,05 mm) and 1.00 in
(25.4 mm)
Diameter, in (mm)
Length, in (mm)
0.0431 (1.09)
0.750(19.05)
1.000 (25.4)
0.0528 (1.34)
0.0676 (1.72)
0.0763 (1.94)
Pai> psia (kPa)
Pdow. psia (kPa)
Tuo °Ff°C)
T„b°F(°a
379.66 (2618)
132.71 (915)
90 (32.2)
20(11.1)
100 (37.8)
10(5.6)
105 (40.6)
S (2.8)
110(43.3)
0(0)
110(43.3)
5%
85
-------
Table B5: Oil Tests for AC9000
Diameter, in (mm)
Length, in (mm)
0.0528(1.34)
0.500 (12.7)
0.0676 (1.72)
P„ psia (kPa)
Pj«w» psia (kPa)
T.-FCO
T^'Fra
221.06(1524)
93.65 (646)
75 (23.9)
20(11.1)
85 (29.4)
10(5.6)
90 (32.2)
5 (2.8)
95 (35)
0(0)
95 (35)
5%
271.25 (1870)
93 .65 (646)
90 (32.2)
20(11.1)
100 (37.8)
10 (5.6)
105 (40.6)
5(2.8)
110 (43.3)
0(0)
110(43.3)
5%
329.31 (2271))
93.65 (646)
105(40.6)
20 (11.1)
115(46.1)
10 (5.6)
120 (48.9)
5 (2.8)
125 (51.7)
0(0)
125 (51,7)
5%
86
-------
Table B6: Oil Tests for AZ20
Diameter, in (mm)
Length, in (mm)
0.0431 (1.09) Middle Pressure Only
0.500 (12.7)
0.750 (19.05) Middle Pressure with 0.0528 (1.34)
and 0.0676 (1.72) Only
1.00 (25.40) Middle Pressure with 0,0528 (1.34)
and 0.0676 (1.72) Only
0.0528 (1.34)
0.0676 (1.72)
0.0763 (1.94) Mic
die Pressure Only
PUD psia (kPa)
fimm psia (kPa)
Tuo °F (°C)
T„b°Fra
309.79 (2136)
132.7,1 (915)
75 (23.9)
20(11.1)
85 (29.4)
10(5.6)
90 (32.2)
5 (2.8)
95 (35)
0(0)
95 (35)
5%
379.66 (2618)
132.71 (915)
90 (32.2)
20(11.1)
100 (37.8)
10(5.6)
105 (40.6)
5 (2.8)
110(43.3)
0(0)
110(43.3)
5%
460.66(3176))
93.65 (646)
105 (40.6)
20(11.1)
115(46.1)
10(5.6)
120 (48.9)
5 (2.8)
125 (51.7)
0(0)
125(51.7)
5%
87
-------
Data Quality Objectives
The quality assurance plan was formed to specify the type of data necessary to
formulate a flow model for short tube orifices and to quantify the acceptable error in any
measurements undertaken during that effort. Before any tests were performed, all equipment
was inspected and calibrated. During the process of generating data for the flow model, a
quality assurance supervisor audited the test facility to determine if data quality goals were
being met. Every effort was made to insure consistent and accurate measurement of the
primary variables. A copy of the quality assurance report is included as Appendix C. Table
B7 lists the variables necessary for the flow model in addition to the measurement method and
associated error.
Table B7: Data Quality Summary for Directly Measured Variables
Measured
Quantity
Measurement
Method
Bias Error
Precision Error
Total Error
Acceptable
Total Error
Pressure
Stainless Steel
Diaphragm
Pressure
Transducer
0.1% of
measured value
*s 0.5 psia
(3.4 kPa)
k 0.8 psia
(5.5 kPa)
1 psia
(6.9 kPa)
Temperature
Thermocouple
T-type
0.2°F
(0.36°C)
0.3°F
(0.S4°O
0.5°F
(0.90°C)
1.0°F
(1.8°C)
Mass Flowrate
Coriolis Effect
Mass Flow
Meter
0.4% of
measured
flowrate
18 lbm / h
(8.2 kg/h)
* 19.0 lbm Ih
(8.6 kg/h)
30 lbm / h
(13.6 kg/h)
Length
Dial Calipers
0.0005 in
(.012 mm)
.001 in
(.025 mm)
0.0015 in
(.038 mm)
0.002 in
(.050 mm)
Diameter
Plug Gages
0.00001 in
(.00025 mm)
0.0005 in
(.012 mm)
0.00051 in
(.013 mm)
0.001 in
(.025 mm)
Heat Tape
Power
Watt Transducer
0.5% of reading
Unknown
0.5% of reading
NA
Weight
Balance Beam
Scale
.017 oz
(0.5 g)
,035 oz
(1.0 R)
.053 oz
(1.5 ft)
.053 oz
(Ug)
Pressure measurements were performed at various locations around the flow loop.
During testing the upstream pressure had to be maintained within ±1 psia (6.9 kPa) of the
88
-------
desired value for the data to be acceptable. Any data that fell outside of this range was not
used to develop the flow model, but it was still included in the data comparison shown in
Appendix A. The main reason for the upstream pressure criteria not always being met was the
inability to match pump speed and bypass valve opening to produce the desired pressure. The
diaphragm pump used to circulate the refrigerant consisted of three separate diaphragm
cavities. If the pump speed were allowed to drop too low, the resulting flow pulsations would
cause pressure to oscillate. To prevent these oscillations, the pump speed needed to remain
high, with the main flow adjustment being initiated with the bypass valve.
Temperatures were controlled using the hot water and chilled water flow loops and
their various bypass and control valves. At low mass flowrates, the temperature of the
upstream refrigerant was easily maintained. As orifice diameter increased, increasing mass
flowrate caused more variation in the upstream temperature. Upstream temperature control
was also affected by upstream pressure control. Higher pressures caused higher flowrate
which in turn lowered the upstream temperature. If the hot water flowrate was not adjusted
accordingly, the upstream temperature could vary beyond the limit specified. Generally, any
data that failed to meet temperature control criteria was discarded and the tests retaken.
Mass flowrate was measured with a coriollis effect mass flowmeter in the subcooled
liquid line before the heat tape and orifice test section. Mass flowrate was the variable being
modeled and therefore care was taken to assure accurate mass flow determination. Before
testing with each refrigerant, the meter was calibrated using warm water. A bucket and stop
watch method was used. Generally linear calibration produced agreement within 1% of the
values supplied by the manufacturer. The main factor affecting steady flowrate was the
pulsing nature of the three cavity pump. Pump rpm was kept high to maintain smooth flow
through the flow meter.
89
-------
Length and diameter were measured using a dial caliper and wire gages, respectively.
All measurements of orifice dimensions were made prior to installation of the short tube in the
copper tubing. If a series of tests revealed that mass flowrate was not consistent with the
measured diameter, the orifice was removed and checked for burrs or other debris which
could impede flow. Several orifices were reconstructed after inspection revealed burrs or
machining marks on the brass surface. New tests were then performed with the replacement
short tube orifices. The data presented in Appendix A includes some orifices that were not
specified in the test matrices. These orifices were slightly larger than initial measurements
suggested. The orifices that were used in modeling the flow were of the same diameter, but
some of the off diameter data has been compared to the model.
In calculating the mass percentage of oil in the system, it was necessary to accurately
measure the weight of the sampling vessel both before and after samples were taken. The
accuracy of the scale used was sufficient to meet standards prescribed by ANSI/ASHRAE
(1984).
Quality of Calculated Parameters
The variables which were directly measured were used in calculating other quantities
such as upstream quality, upstream subcooling, and refrigerant properties. This section
presents the propagation of error analysis for these calculated quantities.
Inlet Quality
An energy balance on the heat tape section of the flow loop revealed the expression
used to calculate inlet quality:
90
-------
x = Ql l fy"
where x = quality (mass vapor / total mass)
Qh = heat energy added, Btu/min (Watts)
Ql = heat energy lost through insulation, Btu/min (Watts)
ih - mass flowrate of refrigerant, Ibm/ min (kg/h)
hfg - enthalpy of vaporization (hg - hf), Btu/lbm (kJ/kg)
hi„« heat tape inlet refrigerant enthalpy, Btu/lbm (Id/kg)
hf = enthalpy of saturated liquid, Btu/lbm (kJ/kg)
hg = enthalpy of saturated vapor, Btu/lbm (kJ/kg)
The propagation of error through the quality equation can be determined using the following
equation:
CO2 =
JT
dc
\
-co,
dc
"%I +
fa V
CO-, +
Km J
/
dc
Y
-co.
A, V
dc
-co.
\2 ( _ \2
dc
\»r "'j
co.
J
Using the equation for quality, the error propagation equation reduces to the following form:
a>„J =1 C°Qh
mh#
V ,f
* t
J '1
+
\
«*(Qh-Ql)'
m2h
CO,
G)
mhfe
ft /
k,(QH "Ql +m(h«, -hf)-mhfc)y f®k,(Qii -Ql +™(l>il -hf)f|2
lk s
iiih %
/
91
-------
Table B8: Uncertainty of Quantities Used to Calculate Quality
Uncertainty
Value
aQn
0.5% of reading
<°ql
1,0 Btu/min (8.8 W)
0.3 Ib/min (4.1 kg/h)
0.02 Btu/lbm (0.023 kJ/kg)
0.02 Btu/lbm (0.023 kJ/kg)
W\
0.01 Btu/lbm (0.012 kJ/kg)
Oil Concentration
Gil concentration was determined by taking a one pound (0,45 kg) sample from the
system. The sampling vessel was evacuated and weighed prior to pulling the sample. Once
the sample was taken, the vessel containing the refrigerant and oil was weighed. Then the
refrigerant was allowed to slowly bleed out through the filter and capillary tube assembly.
Once the vessel reached atmospheric pressure, it was evacuated for several hours and then
weighed. The following expression was used to calculate oil concentration:
p _ Myo ~ My
wn —
MVqr Mvo
where C0 = oil concentration, 02. oil/ oz. refrigerant (g oil/ g refrigerant)
Mvo = mass of the vessel and oil, ounces (grams)
Mv = mass of the vessel, ounces (grams)
Mvor = mass of the vessel, oil, and refrigerant, ounces (grams)
Using this equation, the propagation of error through the oil concentration equation could be
calculated as follows:
( V ( XT V f ao \2
I . I
+
ac0
,mvo vaMv Mv krnvm v
92
-------
©Mvo(MVOR "Mv)
2
4.
® MV
2
4.
<°Uot(MVO-Mv)
(MVOr — Myo)
_(Mvor - Mvo)_
where eo0 ~ uncertainty in oil concentration
wMm = uncertainty in mass of oil, ounces (grams)
cor - uncertainty in mass of refrigerant, ounces (grams)
Uncertainties Calculated
The uncertainty in upstream quality and oil concentration was determined using actual
test data. Table B9 and BIO gives examples of uncertainty for tests done with the ternary and
binary refrigerants. All uncertainties are based upon a 95% confidence interval with:
95% Confidence Interval = X ± Wx
% Error - (WJ X * 100%)
Table B9: Example Quality Uncertainty Values
m , Ib/h
(kg/h)
Qh ,
Btu/min
(Watts)
Ql,
Btu/min
(Watts)
hit.
Btu/lbm
(kJ/kg)
Btu/lbm
(kl/kg)
Btu/lbm
(kJ/kg)
X
w.
% Error
AC9000
171 (78)
11.27
(198)
1.67
(29)
51.53
(119.9)
52.62
(122.4)
123.47
(287.2)
.0321
.007054
22
171 (78)
11.28
(198)
1.67
(29)
51.54
(119.9)
52.74
(122.7)
123.45
(287.1)
.0306
.007064
23
174 (79)
11.31
(199)
1.68
(30)
51.54
(119.9)
52.73
(122.6)
123.64
(287.6)
.0314
.006878
22
AZ20
123 (56)
12.9
(227)
1.86
(33)
49.50
(115.1)
49.38
(114.9)
119.28
(277.4)
.0786
.013219
17
126 (57)
13.49
(237)
1.94
(34)
49.41
(114.9)
49.38
(114.9)
119.28
(277.4)
.0791
.013159
17
183 (83)
13.89
(244)
1.98
(35)
49.50
(115.1)
49.38
(114.9)
119.28
(277.4)
.0730
.007244
13
93
-------
Table BIO: Example Oil Concentration Uncertainty Values
Refrigerant
Mv, oz (f.)
Mvor. oz (r)
Mvo, OZ (g)
Co
Wr„
% Error
AC9000
130,8 (3708)
148.1 (4197,5)
1310 (3713.5)
0.01136
0.002939
26
A220
131.4 (3726.5)
147.8(4189.5)
131.8(3736)
0.0215
0.003152
- 15
94
-------
APPENDIX C
QUALITY ASSURANCE AUDIT REPORT
95
-------
ncNRiCAi smuts audit
QUALITY ASSUKANCi AUOIT CNICX11ST
Air f Energy Engineering Research laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carol 1ni VIM
Outfit Subject: Date: &uau«t ?6, iqqa
Audltee: Lead AudnorjMariri fy>i»T»nc*
location: pohertv Room 102 Auditor Affiliation: ^ ^
Personnel Present During Audit: Vance Pajne __
University
Audit Question
Response
. Yes* I ' Ho K N/A
i
Comments
k. General
Is a written and approved quality
assurance Project Plan available for this
project?
X
"s
I. Laboratory Procedures
Is the calibration of Instruments and
equipment performed according to the OA
Project Plan?
x
March 14, 1994-
August 23# 1994
Are duplicate samples analyzed? (What t
of thl time?)
X
Every Sample
Are spiked samples used? (What I of the
time?)
X
Does the laboratory participate 1n an
Interlaboratory QC program?
X
•
96
-------
Plfi I of I
TECHNICAL SYSTEMS AUDIT
QUALITY ASSURANCE AUDIT CHECKLIST
Date: ftygyif gfi |9H
Audit Ouestlon
Response
tes 1 ho 1 k/k
Comments
Laboratory Facilities arid Eauloment
Are all Instruments and equipment 1n
operating condition?
X
Are written SOPs available for all Instru-
ments and procedures?
X
Is glassware properly cleaned according
to the laboratory SOP?
X
Does a schedule for preventive
maintenance exist?
X
Are QC procedures for maintaining and
servicing equipment available?
X
Are Inspections and maintenance of facili-
ties and equipment conducted regularly?
(By whom, and who receives reports?)
X
By graduate
Does the QAO inspect records for equipment,
consumables, and services? (How frequent-
ly, and what corrective action is taken?)
X
Are balances calibrated at regular
intervals? (Specify intervals.)
X
97
-------
TECHNICAL SYSTEMS AUDIT
QUALITf ASSURANCE AUDIT OCCW.tr
DateAwautt 26. f f94
Audit Ouestlon
iesoonse
Yes 1 Ho 1 N/A
Comments
C. Laboratory Facilities and Equipment
(Continued)
'
Art all measurement devices (e.g.* pH
meters and automatic pipettes) calibrated
before use?
X
i D. Sarnpl1nq
Are samples collected 1n a representatlve
manner? (Describe*)
X
Is the duration of sampling sufficient to
detect all Important.pollutant(s) gener-
ated by the process under Investigation?
X
Art the number of samples collected suf-
ficient to satisfy the completeness
requirements specified 1n OA Project Plan?
X
Were dupllcatt or replicate samples taken
for each sampling location?
X
Is the integrity of each sample
maintained? .(Describe)
X
. Sealed under presaur
in cooper table
Was sampling performed in accordance with
the approved QA Project Plan?
X
Notebook entry (MB)
/ere uniform procedures followed for the
col lection of field blanks, container
clean-up, and the preservation of samples?
X
•
98
-------
Nge 4 of I
TECHNICAL SYSTEMS AUDIT
QUALITY ASSURANCE AUDIT CHECKLIST
OltCi Auamt 26, 1»9<
Audit Question
Resoonse
Yes I No 1 N/A
Comments
3. Sampling (Continued)
' Were samples adequately labeled; and were
sample custody requirements, as specified
In the OA Project Plan, implemented.
X
Is there a Standard Operating Procedure
or other source of documentation which
describes the organization's sample
custody orocedures?
X
Are records available of when, how, and
where the sample was collected?
X
NB
Are records available of who collected
the sample?
X
NB
Are records available of who collected
the sample and how the sample was pre-
pared and transported to the laboratory?
X
NB
Are records available of when the samples
were prepared and transported to the tab*
oratory, and of who performed this task?
X
NB
Is there someone designated as the sample
custodian?
X
Is there a designated receipt location
for samples 1n the laboratory?
i
X
99
-------
quality mmrni audit checklist
&**•: ftMBHit .11.- Iff! ' .
Audit Question
fteseense
Veil KoIM
Commenti
>. Sampling (Continued)
Art the date and condition of the sample
upon receipt documented?
X
Samples mm when
received
Art samples Individually Identified by
number or code so that they can be traced?
X
Art records available as to how the sample
was stored upon receipt?
X
If there a system for documentation of the
K!story of the sample after It has been.
Jogged Into the laboratory? (Describe.)
X
Art records available of when the sample
was extracted and analyzed, and of who
perforated these tasks?
f
. x
\
Once analysis has been completed, are
records available of the fate of the
remainder of the sample {e.g.. storage
or disposal?
* *
X
Were deviations from all SOPs or pro-
tocol s properly documented?
X
-
Analysis
was the analysis performed 1n
accordance with the QA Project
Plan?
X ¦
100
-------
Page • of f
TECHNICAL SfSTIW A*>*T _
QUALITY ASSURANCE AUDIT CHECKLIST
Date: Amqu>t 26, 1994
Audit Question
Response
Yes 1 NO 1 N/A
Comments
E. Analysis (Continued)
'
•
Is the time between collection end
analysis reasonable for every sample?
X
Are samples stored under appropriately
controlled conditions? (4.g., tempera- •
ture, 1 Ight, and humidity)?
X
Are all* Instruments calibrated prior to
anilyiisT"
X
i
Are ftheiOC-procedures specified in the
OA 'Project Plan being implemented?
X
, 4 i j, i v; • ii • -»* -•*'¦>' a v> -.»
Are sample preparation and extraction
procedures documented and implemented
accordingly?
X
Are .analytical procedures and associ-
ated SOPs documented and implemented
accordingly?
X
Are calculations verified? (Describe.)
X
Has the Lab successfully participated
in previous performance evaluation
.studies? (Describe record)
X
loi
-------
P«9t 7 of t
TECHNICAL STSTWS AUDI? . —
QUALITY ASSURANCE AUDIT CHECKLIST
* *"H".* *« 'aq*
Audit Ouestlon
Response
Yes No 1 A/A
Comments
£. Analysis (Continued)
Art control samples used to ensure that
valid data are being generated?
X
Were field spikes used to assess loss
due to storage, handling, and chemical
analysis?
X
Art the Identities of the specific Instru-
ments used 1n the study documented?
X
•
Art the detection limits of Instrumenta-
tion appropriate for the samples under
investigation?
X
Is an Instrument log or record maintained
describing when the Instrument was used
andt Its condition?
X
If microprocessors or laboratory data
management systems are used, are hard
copies available?
X
If problems arise with instrument perfor-
mance, do instrument logs or records
record the pertinent Information?
•
* *
Were field biased blanks and/or trip
blanks used?
X
-
102
-------
TECHNICAL SYSTEMS XOfitT
QUALITY ASSURANCE AUOIT CHECKLIST
Response
Audit Ou«st1on
[KH9KHEH1
Comments
F. Standards and Reagents
r
•
Are standards or reference Materials
available to perfom periodic QC checks?
X
Are the source and quality^ fclVstiri^'
dards or reference natiHali dociMftttifi''*
i i
X
•
f
Are standard solutions* reigents.^and
solvents appropriately labeled?
> ¦
I 4
Are records retained for the source of
standard solutions, solvents, reagents,
etc.?
X
-
Are records available for the source and
purity of solvents, reagents, etc.?
X
i
Are standards or reference naterlals
discarded after the recommended shelf life
has expired?.
' ¦*
X
j
i
i
i
Are background reagents and solvents
run with every series of samples?
X
j
r
i
103
-------
*let 9 9* J
TtCKKICAL SYSTEMS AUOIT
QUALITY ASSURANCE AUDIT CHECKLIST
'• 1
0»tt: »|
1 .
Audit Ouestlon
Response
Comments
res
No
H/k
i
•
i
-
-
-
i
-
*
•
104
-------
AUDIT OF DATA QUALITY
105
-------
AUDIT OF DATA QUALITY
QUALITY ASSURANCE AUDIT CHECKLIST
Air I Energy Engineering Research laboratory
U.S. Environmental Protection Agency
Research Triangle Park, Worth Carolina 27711
Audit Subject: Date; August 26, 19§4
Audi tee; Lead Auditor: MarioCoikluca""
Location; Soherty Room 102 "" Auditor Afff 11at 1 on: Texas MM
Personnel Present During Audit: Vance Payne nm^r-cit-v
' Dating rs'KfeaT
Audit Question
Resoonst
Ves i HO | H/K
Comments
A. Data Quality Indicators
-
Are all data routinely assessed for pre-
cision and bias?
X.
•Frcro Notebook (NB)
Are guidelines 1n the "Chapter 5" docu-
ment used for determining precision and
bias? (If not, describe method used.)
X
Is there a record of the determination
of precision and bias for each result?
X
On floppy discs
Were the data quality objectives for
precision and bias net? (If not, were
deviations justified?)
X
'
Were the data quality objectives for
completeness met? (If not, were the
reasons documented?)
X
Does the degree of data representative-
ness and comparability achieved meet
project plan objectives?
X
106
-------
AUDIT or DATA QUALITY
QUALITY ASSURANCE AUOIT CHECKLIST
Date August 26/ 1994
Audit Question
Resoonse
res 1 No n/a
Comments
A. Data Quality Indicators (Continued)
Is a method detection limit given for
each analytical method described 1n
the project plan?
X
Is there a description of how the method
detection limits were determined?
X
•
If assumptions were used In statistical
analyses of dan, are these described? .
X
-
» t
Are reasons given for missing samples or
data?
X
*
Were the overall data quality objectives
of the study achieved?
X
i. Data Generation
Are all calculations shown or described? .
X
Are some fraction of the calculations
checked by another person? (Can this
person be identified?)
X
Are control charts or other techniques
routinely used to evaluate precision
and bias?
X
107
-------
AUDIT OF DATA QUALITY
QUALITY ASSURANCE AUDIT CHECKLIST
Date: August: 26, 1994
Audit Ouestlon
Resoonse
Tes 1 m | N/A
Comments
B. Data Generation (Continued)
» r
Art procedures for Identifying outliers
documented and applied?
X
Are "significant figures" established
for each analysis?
X
Are "round-off rules* uniformly applied?
X
C. Data Process 1 no
•
•
Is there an Individual responsible for
checking data transcriptions? (Can the
Individual be Identified?)
X
'
Graduate Student
(V.P.)
Are computer programs documented and
validated?
X
Are duplicates of raw data kept?
•
«~
X
V.P.
Is there an Individual responsible for
maintaining data files?
X
>
' Are there SOPs or other written documenta-
tion for data transcription and retrieval ?
(Are these procedures followed?)
X
*
108
-------
AUDIT OF DATA QUALITY
QUALITY ASSURANCE AUDIT CHECKLIST
pa . August 26/ 1994
Audit Ouestion
Response
Yes 1 No 1 N/A
Comments
C. Data Processing (Continued)
Are data collected and recorded In a
standard format?
X
Are data formatting guidelines consistent
within the Lab?
X
•
For routine measurements, ire appropriate
data validation methods specified (control
charts, outlier tests, etc.)?
X
.
Have report forms been developed to pro-
vide complete data documentation to
facilitate data processing?
X
Are data reported 1n proper units?
X
, Notebooks
•
•
Are entries in a non-erasable medium?
X
Is the author of an entry identifiable?
X
i
Reproduced from
best available eopy-
109
-------
AUDIT OF DATA QUALITY
QUALITY ASSURANCE AUDIT CHECKLIST
Pitt,* August 26# 1994
Audit Question
Response
res i no | H/A
Comments
0. Notebooks (Continued)
-
Art entries dated?
X
Are changes in entries documented.
Initialed, end dated?
X
..
Are entries clean and understandable?
X
•
Is there a Table of Contents or Index
to find specific entries In a notebook?
X
Are there erasures or excised pages In
notebooks?
X
*
Are entries and calculations 1n laboratory.
notebooks required to be countersigned?
*
X
110
-------
AUDIT OF DATA QUALITY
CHECKLIST FOR PROCEDURES USED TO PRODUCE FINAL RESULTS
FRON RAW DATA
DateJ August 26, 1994
Procedural Step
(In reverse order)
Description of
Calculations Performed
Satisfactory
Yes
NO
Comments
I. Data in Final
* Report
•
2.
•
¦
-
3.
•
*
r
*
>•
•
•
-
111
-------
APPENDIX D
EXAMPLE THERMODYNAMIC STATE OF THE TEST
REFRIGERANTS
%
The use of zeotropic refrigerant blends introduces the concept of the temperature glide
into the design of air conditioning components. The zeotropic ternary blend tested in these
experiments (AC9000) shows the characteristics of all zeotropic refrigerants; most notably,
the temperature glide produced during a change of phase from a saturated liquid to a saturated
vapor. Figures D1 and D2 can be used to compare the characteristics of the two types of
refrigerants. Figure D1 shows that temperature does not remain constant while the refrigerant
condenses or evaporates for a given pressure. This is due to the different vapor temperatures
of the various constituents in the refrigerants. The zeotropic refrigerant will not have the
same bubble point and dew point temperature. This is contrary to the constant bubble and
dew point temperatures seen with the more commonly used azeotropic refrigerants. Table
Dl, a sample of the thermodynamic property data for AC9000, is included in order to
familiarize the reader with the concept of the temperature glide.
The realm of operation of the expansion device in an air conditioning unit can be seen
in Figure D3. Refrigerant upstream of the expansion device is in a subcooled state shown by
point A on the figure. As the refrigerant moves throughout the expansion device, pressure
drops rapidly as the refrigerant vaporizes under the two-phase "dome" until reaching the
downstream pressure at point B on the figure.
In an actual heating or cooling cycle, the refrigerant would follow the state path
ABCD. For the short tube orifice test bench the refrigerant only traverses the path ABEF as
112
-------
seen on Figure D3. It is unnecessary to completely vaporize the refrigerant since we are only
concerned with the expansion device performance.
Line of constant temperature
Pressure
Dew Point
Bubble Point
ted Liquid
Saturated Vapo
Enthalpy
Figure D1: Sample Pressure-Enthalpy Diagram for a Zeotropic Refrigerant
113
-------
Constant Temperature
Pressure
Bubble Point - Dew Point
turated Liquid
Saturated Vapor
Enthalpy
Figure D2: Sample Pressure-Enthalpy Diagram for an Azeotropic Refrigerant
Pressure
El B
Enthalpy
Figure D3: Operating Regime of the Short Tube Orifice Test Bench
114
-------
Table Dl: Thermodynamic Properties of
the Saturated Liquid and Vapor Phases for SUVA* AC9000
Engineering Units
T. *F
60.00
61.00
62.00
63.00
64.00
65.00
66.00
67.00
66.00
69.00
70.00
71.00
72.00
73.00
74.00
75.00
76.00
77.00
78.00
79.00
80.00
81.00
82.00
83.00
84.00
85.00
86.00
87.00
88.00
89.00
90.00
91.00
92.00
93.00
94.00
95.00
96.00
97.00
98.00
99 .00
P. PaU
130.82
132.94
135.07
137.23
139.42
141.63
143.87
146.14
148.43
150.75
153.10
155.47
157.87
160.30
162.75
165.24
167.75
170.29
172.86
175.45
178.08
180.73
183.42
186.13
188.87
191.65
194.45
197.28
200.15
203.04.
205.97
208.92
211•91
214.93
217.98
221.06
224.18
227.32
230.50
233.71
Saturated Liquid Phase
D-lb/ft1_ I .
H.Btu/lb S.Btu/lbR
P. P8la P.tlb/fl:
73.204
73.065
72.926
72.786
72.646
72.506
72.365
72.224
72.083
71.941
71.799
71.657
71.514
71.371
71.228
71.084
70.940
70.795
70.650
70.505
70.359
70.213
70.066
69.919
69.771
69.623
69.475
69.326
69.176
69.026
68.876
68.725
68.574
68.421
68.269
68.116
67.962
67.808
67.653
67.497
0.02894
0.02941
0.02990
0.03039
0.03089
0.03139
0.03191
0.03242
0.03295
0.03349
0.03403
0.03458
0.03513
0.03570
0.03627
0.03685
0.03744
0.03803
0.03864
0.03925
0.03987
0.04050
0.04114
0.04179
0.04245
0.04311
0.04379
0.04447
0.04517
0.04587
0.04659
0.04731
0.04805
0.04879
0.04955
0.05032
0.05109
0.05188
0.05268
0.05350
32.9338
33.3024
33.6720
34.0426
34.4142
34.7868
35.1604
35.5351
35.9108
36.2875
36.6654
37.0443
37.4243
37.8055
38.1877
38.5711
38.9S56
39.3413
39.7282
40.1162
40.5055
40.8960
41.2877
41.6806
42.0748
42.4703
42.8671
43.2652
43.6647
44.0655
44.4676
44.8712
45.2761
45.6825
46.0903
46.4996
46.9104
47.3227
47.7365
48.1518
0.06956
0.07026
0.07096
0.07166
0.07235
0.07305
0.07375
0.07445
0.07516
0.07586
0.07656
0.07726
0.07796
0.07867
0.07937
0.08008
0.08078
0.08149
0.08220
0.08290
0.08361
0.08432
0.08S03
0.08574
0.08645
0.08717
0.08788
0.08859
0.08931
0.09003
0.09074
0.09146
0.09218
0.09290
0.09362
0.09434
0.09507
0.09579
0.09652
0.09724
109.45
111.35
113.27
115.23
117.20
119.21
121.23
123.29
125.37
127.48
129.61
131.78
133.97
136.18
138.43
140.70
143.01
145.34
147.70
150.09
152.50
154.95
157.43
159.94
162.48
165.04
167.64
170.28
172.94
175.63
178.36
181.12
183.91
186.73
189.59
192.48
195.40
198.36
201.35
204.37
1.9610
1.9953
2.0302
2.0656
2.1015
2.1380
2.1750
2.2126
2.2507
2.2894
2.3286
2.3685
2.4090
2.4500
2.4917
2.5340
2.5770
2.6206
2.6648
2.7097
2.7553
2.8016
2.8486
2.8962
2.9447
2.9938
3.0437
3.0944
3.1458
3.1980
3.2510
3.3048
3.3595
3.4150
3.4714
3.5286
3.5867
3.6457
3.7057
3.7666
0.86272
0.86094
0.85914
0.85732
0.85548
0.85363
0.85177
0.84988
0.84798
0.84607
0.84413
0.84218
0.84022
0.83823
0.83623
0.83421
0.83218
0.83012
0.82805
0.82596
0.82385
0.82173
0.81958
0.81742
0.81524
0.81304
0.81082
0.80858
0.80632
0.80405
0.80175
0.79943
0.79710
0.79474
0.79237
0.78997
0.78755
0.78S11
0.78266
0.78018
118.5043
118.6198
118.7344
118.8483
118.9613
119.0736
119.1850
119.2957
119.4054
119.5143
119.6224
119.7295
119.8358
119.9412
120.0456
120.1491
120.2516
120.3532
120.4538
120.5534
120.6520
120.7496
120.8461
120.9415
121.0359
121.1292
121.2214
121.3124
121.4023
121.4910
121.5785
121.6649
121.7500
121.8338
121.9164
121.9977
122.tt777
122.1563
122.2336
122.3095
0.23608
0.23596
0.23584
0.23572
0.23560
0.23548
0.43536
0.23524
0.23512
0.23500
0.23488
0.23476
0.23464
0.23452
0.23440
0.23428
0.23416
0.23404
0.23392
0.23380
0.23368
0.23356
0.23344
0.23331
0.23319
0.23307
0.23294
0.23282
Q.23270
0.23257
0.23244
0.23232
0.23219
0.23206
0.23194
0.23181
0.23168
0.23155
0.23141
0.23X28 ^
Vcont.
AH_
PtW/lP.
85.5706
85.3174
85.0624
84.8057
84.5472
84.2868
84.0246
83.7606
83.4946
83.2268
82.9570
82.6852
82.4115
82.1357
81.8579
81.5780
81.2960
81.0119
80.7256
80.4372
80.1465
79.8536
79.5584
79.2609
78.9611
78.6589
78.3542
78.0472
77.7376
77.4255
77.1109
76.7937
76.4739
76.1513
75.8261
75.4981
75.1673
74.8337
74.4971
v74.1577
-------
Table Dl- Thermodynamic Propertlee of the Saturated Liquid and Vapor Phasee for SUVA* AC9000
idU1 Engineering Units (cont.)
T."F P * Peia
Saturated Llould Phaee
D. lb/ft Z H.Ptu/lb
100.00
101.00
102.00
103.00
104.00
105.00
106.00
107.00
108.00
109.00
110.00
111.00
112.00
113.00
114.00
115.00
116.00
117.00
118.00
119.00
120.00
121.00
122.00
123.00
124.00
125.00
126.00
127.00
128.00
129.00
130.00
131.00
132.00
133.00
134.00
135.00
136.00
137.00
138.00
139.00
236.96
240.24
243.55
246.09
250.27
253.68
257.12
260.60
264.12
267.67
271.25
274.87
278.52
282.21
285.94
289.70
293.49
297.33
301.20
305.10
309.04
313.02
317.04
321.09
325.18
329.31
333.48
337.68
341.93
346.21
350.53
354.89
359.28
363.72
368.20
372.71
377.27
381.86
386.49
391.17
67.341
67.185
67.027
66.869
66.710
66.551
66.391
66.230
66.069
65.906
65.743
65.579
65.414
65.249
65.082
64.915
64.747
64.578
64.408
64.236
64.064
63.891
63.717
63.542
63.365
63.188
63.009
62.829
62.648
62.465
62.281
62.096
61.909
61.721
61.531
61.339
61.146
60.952
60.755
60.557
0.05432
0.05516
0.05600
0.05607
0.05774
0.05063
0.05953
0.06044
0.06137
0.06231
0.06326
0.06423
0.06522
0.06621
0.06723
0.06826
0.06931
0.07037
0.07145
0.07255
0.07366
0.07480
0.07595
0.07712
0.07831
0.07951
0.08074
0.08199
0.08326
0.08456
0.08587
0.08721
0.08857
0.08996
0.09137
0.09280
0.09427
0.09576
0.09727
0.09882
48.5688
48.9873
49.4075
49.8293
50.2528
50.6780
51.1049
51.5336
51.9641
52.3964
52.8305
53.2P66
53.7045
54.1444
54.5863
55.0302
55.4762
55.9243
56.3745
56.8269
57.2815
57.7383
58.1975
58.6591
59.1231
59.5895
60.0584
60.5300
61.0041
61.4809
61.9605
62.4429
62.9282
63.4165
63.9078
64.4022
64.8998
65.4006
65.9048
66.4125
S.Btu/lbR
0.09797
0.09870
0.09943
0.10017
0.10090
0.10164
0.10237
0.10311
0.10385
0.10459
0.10534
0.10608
0.10683
0.10758
0.10833
0.10908
0.10984
0.11059
0.11135
0.11211
0.11288
0.11364
0.11441
0.11518
0.11595
0.11673
0.11751
0.11829
0.11907
0.11986
0.12065
0.12144
0.12224
0.12304
0.12384
0.12465
0.12546
0.12627
0.12709
0.12791
P. pela
P,lb/ft
207.44
3.8284
210.53
3.8913
213.66
3.9551
216.83
4.0199
220.03
4.0858
223.27
4.1527
226.54
4.2207
229.85
4.2898
233.20
4.3600
236.59
4.4314
240.01
4.5039
243.47
4.5776
246.97
4.6525
250.51
4.7287
254.08
4.8061
257.70
4.8849
261.35
4.9649
265.05
5.0464
268.78
5.1292
272.56 .
5.2134
276.37
5.2991
280.23
5.3863
284.13
5.4750
288.07
5.5652
292.05
5.6571
296.07
5.7506
300.14
5.8457
304.25
5.9426
308.40
6.0413
312.60
6.1418
316.84
6.2441
321.13
6.3484
325.46
6.4546
329.84
6.5628
334.26
6.6731
338.73
6.7856
343.24
6.9003
347.81
7.0172
352.42
7.1365
357.07
7.2582
grig
AH—
lzIL
0.77767
0.77515
0.77260
0.77004
0.76745
0.76483
0.76220
0.75954
0.75686
0.75415
0.75142
0.74867
0.74589
0.74309
0.74026
0.73740
0.73452
0.73161
0.72868
0.72572
0.72273
0.71972
0.71667
0.71360
0.71050
0.70737
0.70421
0.70101
0.69779
0.69454
0.6912S
0.68793
0.68457
0.68119
0.67776
0.67430
0.67081
0.66728
0.66371
0.66010
122.3840
122.4570
122.5286|
122.5988
122.6674
122.7344
122.7999
122.8638
122.9261
122.9867
123.0456
123.1028
123.1583
123.2119
123.2637
123.3137
123.3617
123.4078
123.4519
123.4940
123.5340
123.5718
123.6075
123.6410
123.6723
123.7012
123.7277
123.7518
123.7734
123.7925
123.8089
123.8227
123.8337
123.8419
123.8473
123.8496
123.8489
123.8450
123.8379
123.8275
0.23115
0.23101
0.23088
0.23074
0.23060
0.-23046
0.23032
0.23018
0.23004
0.22989
0.22975
0.22960
0.22945
0.22930
0.22915
0.22900
0.22884
0.22868
0.22852
0.22836
0.22820
0.22803
0.22787
0.22770
0.22753
0.22735
0.22718
0.22700
0.22681
0.22663
0.22644
0.22625
0.22606
0.22586
0.22566
0.22546
0.22525
0.22504
0.22483
0.22461
73.8152
73.4697
73.1212
72.7695
72.4146
72.0565
71.6950
71.3302
70.9620
70.5903
70.2151*
69.8362
69.4537
69.0675
68.6774
68.2834
67.8855
67.4835
67.0774
66.6671
66.2525
65.8335
65.4100
64.9819
64.5492
64.1117
63.6693
63.2219
62.7693
62.3115
61.8484
61.3798
60.9055
60.4254
59.9395
59.4474
58.9491
58.4444
57.9331
57.4150
------- |