APTD-1358
VAPOR GENERATOR FEED PUMP
FOR RANKINE CYCLE
AUTOMOTIVE PROPULSION SYSTEM
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Mobile Source Pollution Control Program
Ann Arbor, Michigan 48105
LEAR MOTORS CORPORATION
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APTD - 1358
VAPOR GENERATOR FEEDPUMP
FOR RANKINE CYCLE
AUTOMOTIVE PROPULSION SYSTEM
CONTRACT NUMBER 68-01-0437
FINAL REPORT
Prepared By
Max K. Winkler
LEAR MOTORS CORPORATION
Reno, Nevada 89510
EPA Project Officers
W. Dyer Kenney and Kenneth F. Barber
Prepared For
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Mobile Source Pollution Control Program
Advanced Automotive Power Systems Development Division
Ann Arbor, Michigan 48105
December, 1972
LEAR MOTORS CORPORATION
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The APTD (Air Pollution Technical Data) series of reports is issued by
the Office of Air and Water Programs, U.S. Environmental Protection
Agency, to report technical data of interest to a limited number of
readers. Copies of APTD reports are available free of charge to Federal
employees, current contractors and grantees, and non-profit organizations
as supplies permit - from the Air Pollution Technical Information Center,
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina 27711 or may be obtained, for a nominal cost, from the National
Technical Information Service, U.S. Department of Commerce, 5285 Port
Royal Road, Springfield, Virginia 22151.
This report was furnished to the U.S. Environmental Protection Agency by
Lear Motors Corporation, Reno, Nevada in fulfillment of Contract Number
68-01-0437. The contents of this report are reproduced herein as
received from the Lear Motors Corporation. The opinions, findings, and
conclusions expressed are those of the author and not necessarily those
of the Environmental Protection Agency.
Office of Air and Water Programs Publication Number APTD - 1358
LEAR MOTORS CORPORATION
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TABLE OF CONTENTS
PAGE
LIST OF TABLES i v
LIST OF FIGURES. v
SECTION
I. INTRODUCTION 1
II. SUMMARY... 2
III. TECHNICAL DISCUSSIONS 6
A. Feedpump Operating Principle and Description 6
B. Feedpump Design Study 8
C. Feedpump Performance Study 14
D. Material Compatibility Study '18
IV. SYSTEM CONTRACTOR TECHNICAL REQUIREMENTS AND LEAR MOTORS
APPROACH
A. Steam Engine Systems - Water base fluid -
Recriprocating Expander 26
1. Pump performance 27
2. Pump Inlet Envelope 29
3. Pump Drive 31
4. General Requirements 33
B. Aerojet Liquid Rocket Company - Organic Fluid -
Turbine Expander 34
1. Pump Performance 35
2. Pump Inlet Envelope 37
3. Pump Drive and Control 39
4. General Requirements 41
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TABLE OF CONTENTS cont.
SECTION PAGE
C. Thermo Electron Corporation - Organic Fluid -
Recriprocating Expander 42
1. Pump Performance 43
2. Pump Inlet Envelope 45
3. Pump Drive and Control 47
4. General Requirements 49
V. CONCLUSION 50
REFERENCES 52
APPENDIX - LEAR MOTORS PUMP STANDARDS 53
Pump Test Code ^-1
Pump Rating Criteria A-5
Net Positive Suction Head Definition A-8
Net Positive Suction Head Calculations A-9
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LIST OF TABLES
TABLE PAGE
1. Summary of Contract Technical Requirements 3
2. System Contractor Feedpump Design Specifications 13
3. Candidate Materials for System Contractor Proposed
Feedpumps 25
LEAR MOTORS CORPORATION
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LIST OF FIGURES
FIGURE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
PAGE
Estimated System Contractors Feedpump performance.
Estimated Feedpump Performance and Typical System
Operating Envelope
Lear Motors Feedpump and Typical Test Stand..
LMC Feedpump Mechanical Efficiency vs. Flow..
LMC Feedpump Performance
LMC Feedpump Net Positive Suction Head Chart.
SES Estimated Pump Performance
SES Estimated Pump Inlet Envelope
SES Pump Outl.ine Drawing
ALRC Estimated Pump Performance
ALRC Estimated Inlet Envelope
ALRC Pump Outline Drawing
TECO Estimated Pump Performance
TECO Estimated Pump Inlet Envelope
TECO Pump Outline Drawing
5
7
15
16
17
28
30
32
36
38
40
44
46
48
LEAR MOTORS CORPORATION
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INTRODUCTION
This report is submitted in fulfillment of Environmental
Protection Agency Contract No. 68-01-0437. The data presented herein
are the results of preliminary design studies conducted to define
feedpumps that satisfy the performance requirements for Rankine
Cycle automotive power systems under development for the Environmental
Protection Agency.
SUMMARY OF SYSTEMS UNDER DEVELOPMENT
System
Contractor
Steam Engine Systems
CSES)
Aerojet Liquid Rocket
Company (ALRC)
Thermo Electron
Corporation (TECO)
Working
Fluid
Demineralized
water.
AEF-78
(Organic fluid)
Fluorinal 85
(Organic fluid)
Type of
Expander
Reciprocating
expander.
Turbine expander,
Reciprocating
expander.
LEAR MOTORS CORPORATION
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II SUMMARY
The approach followed in this study consisted of establishing
feedpump requirements for three (3) separate applications. This was
accomplished in conjunction with the EPA and the three system
contractors. The technical requirements as established by the contract
and subsequent coordination meetings with the EPA and system contractors
are summarized in Table I, and detailed in Section IV. An additional
requirement was to select a single design which satisfied both organic
systems. However, the final selection could not compromise significant
gains in performance or cost reductions resulting from separate designs.
Further investigations revealed that the feedpump developed by
Lear Motors Corporation satisfies the basic requirements of the three
system contractors. This Lear feedpump was used as a baseline for the
preliminary design and performance study presented in this report. A
description of the Lear feedpump and its operating principle is
presented in Section III-A. From the discussion presented in
Section III-A, it can be seen that this Lear Motors pump has been
designed for, and satisfies the basic requirements of; hermetic sealing
of the working fluid, contamination of the working fluid, variable
displacement capability, and low N.P.S.H. capability.
A summary of the flow requirements and estimated brake horsepower
for the three system contractor feedpumps is shown graphically in
Figure 1. These data which show system mass flow and brake horsepower
versus percent of expander speed illustrate the relative magnitude of
the respective requirements. Figure 2 shows the estimated feedpump
performance, with a typical system operating envelope superimposed.
These data show the affect of pump displacement-speed relationship on
pump mechanical efficiency.
Details of the contracts technical requirements and the Lear
Motors approach for each system contractor are presented in Section IV.
These data, showing the estimated pump performance, estimated pump
inlet envelope, and pump outline drawing were derived from actual test
results and physical relationships of the Lear Motors 4th generation
design feedpump.
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SUMMARY OF CONTRACT TECHNICAL REQUIREMENTS
SES
ALRC
TECO
Pump Performance
Type of Expander
Expander Speed
Flow Range and Corner
Condition
Discharge Pressure
Mechanical Efficiency
Pump Inlet Envelope
Inlet Pressure
NPSH Capability
Temperature Range
Temperature Transients
Boost Pump
Pump Drive
Drive Mechanism & Flow
Range Control
Working Fluid
Reciprocating
300-2500 RPM
0-2.5 6PM
Max system flow @ 40% speed
1200 PSIA max.
70% from 30-80% of flow max.
50% min. at 10% of flow max.
0.09 PSIA @ Start
7-50 PSIA operation
Minimized to operate
without boost
180-250 °F Normal
32-275 °F Start
3° per second for 10 seconds
Only if needed
Mechanical with provision
for;variable speed or
variable capacity.
Water - Demineralized
(Pump to have provision
for draining)
Turbine
16,800-31,200
1.85:1 Speed Ratio
0.5-28 GPM
Max system flow @ 54% speed
1100 PSIA max.
70% from 30-80% of max flow
50% min. at 10% of flow max.
1.0 PSIA @ Start
10.0-40.0 PSIA operation
7 inches min. avail
(.45 PSI @ 72 °F)
160-250 °F Normal
-40-275 °F Start
Only if needed
Mechanical with provision
for variable speed or
variable capacity.
Organic
S.G. = 1.793 @ 72 °F
Reciprocating
300-1800 RPM
0-17 GPM
Max system flow @ 45% speed
1000 PSIA max.
70% from 30-80% of max flow
50% min. at 10% of flow max.
0.5 (3 Start
5-90 PSIA during operation
10 inches min. avail.
(149 PSI @ 72 °F)
160-250 °F Normal
-40-275 °F Start
Only if needed
Mechanical with provision for
variable speed or variable
capacity.
Organic
S.G. = 1.368 @ 72 °F
TABLE 1
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Q.
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ESTIMATE OF SYSTEM CONTRACTORS
FEEDPUMP PERFORMANCE
SYSTEM CONTRACTOR
FLOW REQUIREMENTS
10
100
cc
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ESTIMATED FEEDPUMP
BRAKE HORSEPOWER
10
EXPANDER SPEED ~(%)
0 20 40 60 80
EXPANDER SPEED- (%)
100
-------
ESTIMATED FEEDPUMP PERFORMANCE
100
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70
M
TYPICAL NORMAL
OPERATING RANGE
100
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20
20 40 60 80 100
EXPANDER SPEED^(%)
CONTRACT MECHANICAL EFFICIENCY DESIGN POINTS
TYPICAL NORMAL
OPERATING RANGE
20 40 60 80
PUMP MASS FLOW~(%)
100
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Ill TECHNICAL DISCUSSION
In Rankine cycle automotive power systems the feedpump must be
capable of efficiently pumping the working fluid up to system pressure
while operating at very low net positive suction head conditions and
very high fluid inlet temperature to achieve reasonable cycle
efficiencies. Three years ago, Lear Motors initiated the development
of pump specifically designed for Rankine cycle applications. The
results of this development have been used as the basis for these
studies.
A. LEAR MOTORS FEEDPUMP OPERATING PRINCIPLE AND DESCRIPTION
The Lear Motors high pressure feedpump design, incorporates
pistons reciprocating within close fitting cylinders filled with
oil. A flexible diaphragm is positioned between each cylinder
cavity and the working fluid pump chamber. The alternate suction
and displacement of oil by the pistons actuates the diaphragms and
thus results in an equal displacement in the working fluid chamber.
No mechanical connection is required between diaphragm and piston.
Since incompressable fluids are present on both sides of the
diaphragm, pressure across the diaphragm is always equal. The pump
may be operated at any pressure within the structual limits of the
pump without stress upon the diaphragms or any reduction in
diaphragm 1ife.
The pump incorporates a fixed stroke, needle bearing, eccentric
on a drive she.ft which is supported by two ball bearings. The
eccentric converts shaft rotary motion to reciprocating motion and
is used to drive the pistons which are equally spaced around the
drive shaft. On the displacement, or pressure stroke, the eccentric
drives the piston up, pressurizing the oil chamber above the piston
which actuates the diaphragm and displaces the working fluid in the
pump chamber through the outlet valve. During the suction, or
return stroke, the piston is held to the eccentric by a positive
return band and as the piston, oil and diaphragm are drawn back,
working fluid enters the pump chamber through the inlet valve.
The entire drive shaft and piston assembly is located within
the pump's temperature compensating oil reservoir and is completely
lubricated. The oil filled chamber above the piston is connected
to the oil reservoir through a slot in the piston wall and a
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LEAR MOTORS TYPICAL TEST STAND
LEAR MOTORS FEEDPUMP
FIGURE 3
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triangular port in the side of the cylinder. The piston slot must
be closed before oil can be displaced in the chamber above the
piston. That portion of fixed mechanical stroke during which the
piston slot is closed is the effective stroke of the pump. By
varying the cylinder port with respect to the piston slot, the
pump's effective stroke or displacement can be controlled. Each
cylinder is linked mechanically, inside the pump, to an external
pump displacement control shaft which can be actuated directly or
with a small servo mounted outside the pump.
There are no sliding or rotating seals in contact with the
pumped fluid, allowing the pumped fluid to be hermetically sealed
from atmosphere and lubricating oil. All of the highly stressed
moving parts in the pump are oil lubricated allowing conventional,
low cost materials to be used throughout its construction.
Efficient operation of the pump, during low N.P.S.H. conditions of
Rankine cycle system, is made possible by utilization of large
passages and valves designed for minimum flow losses throughout the
inlet circuit of the feedpump.
This feedpump, designed specifically for use with the Rankine
cycle system, is the result of a continuing feedpump development
program at Lear Motors Corporation.
B. FEEDPUMP DESIGN STUDY
Pump size is determined primarily by the system flow require-
ments as defined by the high flow-low speed corner condition. This
point and the mass flow at idle define the mass flow-speed
characteristics slope. By extending the line to 100% expander speed
the flow capability of the pump is defined. Since the system can't
utilize the total capability of the pump, variable displacement or
capacity is required to allow operation within the system envelope.
The corner condition of the pump performance map is determined
by vehicle performance in terms of lugging and acceleration
capability. If system performance is allowed to degrade then the
slope of the pump characteristics can be changed. Thus, a compromise
in system performance is required if one pump design is used for
both organic fluid system contractors. For this study a penalty
in system performance was considered undesirable. Therefore, a
separate pump design was prepared for each system contractor.
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After the high flow-low expander speed corner condition for
each system contractor was established, the maximum speed capability
of each pump was investigated based on an analysis of both radial
and axial piston pump designs.
From this analysis it was determined that maximum speed
capability of the radial pump is limited by the valve dynamics and
speed at which the oil in the pump crank case may be sheared without
excessive friction losses, rather than the dynamic unbalance of the
fixed eccentric on the crank shaft. Further study revealed that
the radial piston design would be physically smaller, lighter in
weight, and less expensive to produce.
Utilizing the established maximum pump speed in conjunction
with the system contractor flow and maximum pressure ripple require-
ments, the bore/stroke relationship and number of cylinders were
selected. To keep the instantaneous total flow of the pump, for any
given crank shaft angle, as smooth as possible, an odd number of
cylinders was used. The number of cylinders and the bore/stroke
relationship determine the displacement of the pump as well as its
smoothness. Obviously the greater the number of pistons for a
given flow the smoother the pump will be, however, pump cost and
physical size must be considered. After close examination of the
parameters involved and based on our four years of feedpump
experience, the bore/stroke relationship and number of pistons
which would best meet the individual system contractor feedpump
requirements was determined.
The diaphragm seals for each pump were then examined. These
diaphragms are the key to the hermetic sealing capability of the
Lear Motors feedpump design. They also enable the pump to produce
high pressure working fluid without utilizing the fluid to lubricate
highly stressed moving components such as piston seals, gear teeth,
or vane tips. The diaphragm effective area selection was based on
several factors: 1) The maximum volume it must displace during
each piston stroke. 2) The physical design of the seal . 3) The
material used to construct this flexible sealing member.
As the Lear Motors feedpump has demonstrated excellent per-
formance with a flat circular sealing member using an elastomer
material, our major effort was directed toward finding elastomers
LEAR MOTORS CORPORATION
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which had the physical properties required and were compatible with
the two organic fluids used by the system contractors.
A separate study was conducted and limited tests for compatibil-
ity were conducted by the organic fluid system contractors on
candidate elastomer materials selected and supplied by Lear Motors
Corporation. The results of this study indicated that several of the
elastomers evaluated, were acceptable for use as sealing diaphragm
material. The suggested procedure and test results are shown in
Section III-D of this report.
An additional investigation into the possible use of a bellows
type metal diaphragm was carried out. However, due to the low cycle
life and high costs quoted by the venders and available design
literature, the use of this type of seal was deemed not practical.
Having established a suitable elastomer material for each of the
system contractors and selected the flat circular diaphragm design,
the minimum effective area required for long diaphragm life was
determined. It is apparent that for a given piston displacement the
larger the effective or flex area of the sealing diaphragm, the longer
the diaphragm life. However, the physical size of the pump, namely its
outside diameter, will become proportionately larger. Therefore, the
minimum area of diameter of the diaphragm becomes an important
individual pump design feature. This sealing member is simply a
flexible incompressible barrier which separates two other virtually
incompressible fluids; the most important physical characteristic of
the elastomer sealing or separating members used in these pumps is
the flex life capability of the elastomer. Fortunately, this is
what most elastomers are compounded for and the selection of materials
is large even when limited by the Rankine cycle system fluid tempera-
ture extremes and material compatibility requirements.
The designed maximum movement or flex used by Lear Motors is
8 to 10 percent change. For each system contractor a specific
diaphragm effective area was determined based on the maximum volume
displaced per piston and the 8 to 10 percent flex value which has
proved successful in the Lear Motors feedpump. It must be pointed
out that during most of the vehicles normal operation the feedpump is
LEAR MOTORS CORPORATION
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functioning at a reduced displacement and the diaphragms would be
flexing less than design.
Having determined the individual system contractors pump, bore
and stroke, number of cylinders, pump speed, and outside diameter
required by the pitch circle of the individual diaphragm seals, a
preliminary analysis of each pumps bearing requirements and operating
mechanics was made. As one of the basic strong points of the Lear
Motors feedpump design is that all of the highly stressed bearings and
moving parts required by the feedpump are oil lubricated, conventional
low cost bearings and materials may be used, making the analysis of
the lubricated section of the pump straight forward. One area in this
lubricated section required special attention. The pumps unique
outlet flow or displacement control, described in Section III-A
Feedpump Operating Principle and Description, must be designed to keep
orifice and passage losses low to maintain high pump mechanical
efficiency.
The next basic area which was examined during this design and
performance study involved the inlet passages and inlet valve sizing.
To reduce the net positive suction head required by the pump for
efficient operation, special attention must be given the working fluid
inlet of the pump. A description of the term net positive suction
head (NPSH) is given in the appendix. Basically, a positive displace-
ment pump is not known for its low NPSH characteristics; any entrained
vapor in the pumped fluid will cause the pump performance to degrade
rapidly. To minimize the NPSH required by the feedpump, the inlet
velocity of the working fluid must be kept as slow as possible so that
the friction losses are kept to a minimum. Also the inlet valve
spring must be kept as light as possible and still allow the valve to
operate at high pump speed. Large inlet passages and inlet valves
which reduce fluid flow velocities were designed into each of the
feedpumps. Maximum inlet velocities of 5 to 6 feet per.second were
used in the design of the Lear Motors feedpump and each of the system
contractor feedpumps. The estimated inlet envelope showing the NPSH
required for each of the pumps is detailed graphically in Section IV
of this report. These data, corrected for individual organic fluid
specific gravity variations, demonstrate what each of the pumps would
be capable of based on actual Lear Motors test data shown in
LEAR MOTORS CORPORATION
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Section III-C of this report.
Further examination of the NPSH required by these feedpumps,
although low for positive displacement pumps, indicates that some
amount of sub-cooling or boost pressure is required to meet the
system contractor requirements. Sub-cooling of the working fluid
results in a significant loss in Rankine cycle system efficiency due to
the power expended in the cooling of the fluid as well as the heat
required to bring it back up to a temperature after it has been
pumped. Adding boost pressure or head to the inlet of the pump by
placing the working fluid reservoir physcially higher than the
feedpump is not practical in an automotive Rankine cycle system due
to the limits of the engine compartment and the added expander back
pressure. However, increasing the inlet pressure to the feedpump with
an independently driven centrifugal pump demonstrates several
advantages; the centrifugal type of pump has inherently low NPSH
characteristics and can be designed to handle significant amounts of
vapor. A centrifugal pump can operate at and below the systems
working fluid vapor pressure line, allowing greater cycle efficiencies
through the minimum sub-cooling required. By mounting a small
separately driven centrifugal pump low in the system the feedpump may
be conveniently mounted and driven without regard to the systems
liquid level. The vehicle will be operational with the absolute
minimum sub-cooling because the independently driven centrifugal pump
will provide some liquid to the feedpump regardless of the expander
speed. An independently driven centrifugal boost pump will allow the
system to be started after a hot shutdown. It was concluded after
examining the parameters involved that a small independently driven
centrifugal pump is important to the efficient operation of an
automotive Rankine cycle system.
Having concluded the preliminary design portion of this study,
an outline or installation drawing for each pump, shown in Section IV,
was drawn. It must be pointed out that these pumps were designed
specifically to meet the individual system contractors requirements
and that their physical size is determined primarily by the systems
high flow-low speed corner condition not just the maximum system flow
required.
Example: A positive displacement pump with flow-speed
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SYSTEM CONTRACTOR FEEDPUMP
DESIGN SPECIFICATIONS
Configuration
Number of
Cylinders
Bore
Effective Stroke
Diaphragm seal
effective are
per cylinder
Pump Design
Theoretical Flow
0 85% Vol. Eff.
System Flow
Requirement
Pump Speed
(Max. Design)
Pump Displacement
VoT/Rev.
Inlet Velocity
@ Max System Flow
Estimated Pump
Weight with
1. Iron Housing
2. Aluminum
Housing*
SES
Radial Piston,
Diaphragm seal
6.2 GPM @ 100
percent speed
2.5 GPM @ 40
percent speed
2400 RPM
.77 in3/Rev.
5.1 FPS
16 1/2 pounds
12 pounds
AJLRC
Radial Piston,
Diaphragm seal
52 GPM @ 100
percent speed
28 GPM @ 54
percent speed
2000 RPM
6.52 in3/Rev.
5.9 FPS
108 pounds
81 pounds
TECO
Radial Piston,
Diaphragm seal
.68 inches
.41 inches
2.08 in2
1 .25 inches
.75 inches
6.51 in?
1 .18 inches
.67 inches
5.43 in2
40 GPM @ 100
percent speed
17 GPM (3 45
percent speed
2000 RPM
4.64 in3/Rev.
5.5 FPS
66 pounds
46.5 pounds
Additional stress analysis required.
TABLE 2
13
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characteristics capable of producing 26 GPM (gallons per minute) at
50 percent or one-half speed is theoretically capable of producing
52 GPM at 100 percent or maximum speed. While the system may only
require 26 GPM mass flow the pump must be physically large enough to
produce 52 GPM. The only reduction in pump size, due to the 26 GPM
system requirement, will be working fluid flow passage area. From
this example it can be seen that any reduction of the system
contractors high flow-low speed corner requirement will result in a
significant reduction in the feedpump size and weight.
C. FEEDPUMP PERFORMANCE STUDIES
Estimates of the individual system contractor proposed feedpumps
performance and inlet envelope are shown graphically in Section IV.
These estimates were obtained by extrapolating actual Lear Motors
Corporation feedpump test data. The procedure and feedpump rating
criteria used in conducting the tests, which were run specifically
for this study, are shown in the Appendix.
The proposed feedpump estimated performance curves, showing pump
brake horsepower, mechanical efficiency, and flow vs. pump and ex-
pander speed, demonstrate the broad range over which these pumps can
operate. The lower section of these pump performance maps, indicate
the flow characteristics of the pump at various speeds and displace-
ment levels. Superimposed are the 50 and 70% mechanical efficiency
lines denoting how the pump performs with respect to contractor
performance requirements. Also indicated is the pumps full displace-
ment flow line the slope of which is determined by the individual
system maximum flow-minimum expander speed corner condition and the
volumetric efficiency of the pump. Based on Lear Motors Corporation
feedpump data, full displacement volumetric efficiency of the proposed
pumps will be 85 to 90% depending on outlet pressure and inlet
N.P.S.H.
Feedpump inlet envelope estimates are also shown in Section IV,
under the individual system contractor heading. These inlet envelopes,
superimposed over the contractors working fluid vapor pressure
characteristics, demonstrate the N.P.S.H. required by the pump to
maintain efficient operation. The pressure and temperature limits
during normal and extreme operating conditions, as outlined by the
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100
90
80
Z
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3
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MECHANICAL EFFICIENCY VS PUMP FLOW
Silver 4-cv Bus Pump
Test Conditions:
Outlet Press.-- 1000 PSIG
Suction Press.- 15 PSIG
Water Temp. 75-90°
Mech. Eff.= W-H-P- x ion
456
PUMP FLOW~ GPM
FIGURE 4
15
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20
30
40 50 60
PUMP SPEED -- PER CENT
70
80
90
100
Full Displacement Mech. Eff.
PUMP PERFORMANCE
4-CV Bus Pump
Test Conditions:
Outlet Pressure -
Suction Pressure-
Water Temp. - - -
- 1000 PSIG
- 15 PSIG
- 100-160° F
s
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\
CX,
s
d.
10
9
8
7
6
5
4
3
2
1
20
30
40 50 60
PUMP SPEED - PER CENT
70
80
90
100
90
80 \
70 I
M
60 M
50 w
_]
40 3
30 |
20 s
707.
Mech
Eff
50%
Mech
Eff
100
200 400 600 800 1000 1200
" PUMP SPEED ~ RPM
1400 1600 1800 2000
FIGURE 5
16
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92.5
S2.5-
NET POSITIVE SUCTION HEAD (NPSH) CHART
Fluid - Water
Conditions - 5000 Ft Altitude
NPSH = hs-(hvp-ha)
Where:
hs=Static Suction Head
at Pump Inlet (Gage)
=Vapor Pressure (Absolute)
ha=Atmospheric Pressure
(Absolute)
O -- DATA POINTS
PUMP SPEED 1260 RPM
Open Pot
Boiling Point of
Water @ 5000 Ft.Alt.
(12.5 PSIA @ 204° F Nominal)
150
160
210 220
TEMPERATURE -
280
290
-------
contract requirements, are also indicated.
Minimum N.P.S.H. characteristics shown were taken directly from
Lear Motors feedpump data, corrected only for the individual
contractors working fluid specific gravity. It has been our
experience, as pointed out in the feedpump design studies, that while
the minimum N.P.S.H. characteristics of the Lear Motors feedpump
design is low, significant gains in Rankine cycle efficiency are
obtained by using an externally driven boost pump designed to handle
even lower N.P.S.H. conditions.
D. MATERIAL COMPATIBILITY STUDY
The proposed feedpumps utilize a flexible diaphragm to provide
positive hermetic sealing of the working fluid from the atmosphere
and oil contamination. Lear Motors Corporation has found that many of
the common elastomers demonstrate all of the physical qualities
necessary to effect this seal. However, compatibility with the
working fluid must be established.
At the first contract coordination meeting, due to the small
number of elastomers which had been tested, it was decided that each
of the organic fluid system contractors should perform compatibility
tests on candidate elastomers and non-metallic materials. Samples
of the candidate materials and a suggested test procedure were pro-
vided by Lear Motors Corporation.
The compiled results of these tests as well as additional data
from the system contractors and an organic fluid manufacturer are
shown. A summary of the elastomers which are acceptable for the
feedpump sealing diaphragms follows:
THERMO ELECTRON CORPORATION - Organic Working Fluid-Fluorinol 85
Elastomers which have passed initial compatibility tests with
the TECO.organic working fluid at 250°F.
1. Silicone Rubber, Parker-Compound No. S455-7.
AEROJET LIQUID ROCKET COMPANY - Organic Working Fluid AEF-78
Elastomers which have passed initial compatibility tests with
the ALRC organic working fluid at 250°F.
1. Silicon-Rubber - (Dow Corning L-53).
2. Silicon Rubber - (Dow Corning L-63).
LEAR MOTORS CORPORATION
18
-------
3. Chloroprene Rubber - (Dupont "Neoprene").
4. Polysulfide Rubber - (Thiokol Chemical Corp.).
The results of these preliminary tests have demonstrated that
elastomers for use with the organic working fluids are available.
However, due to the short term and limited scope of these tests, Lear
Motors recommends additional investigations.
LEAR MOTORS CORPORATION
19
-------
Results of Material Compatibility
Tests Performed by Thermo Electron Corp.
Test Conditions:
Solution -
Temperature -
LMC Candidate
Material
Chloroprene Rubber
Florinol 85 and oil (10 to 1 ratio)
250°F
Percent Weight
Change
+ 6.8
Time
(days)
17
Nitrel
+ 8.3
17
Polyimide
(Dupont) Vespel SP-1
Polyamide DFS-20
(experimental-Dupont)
CONCLUSIONS
+ .48
+ . 11
Visual Observations
Surface corroded, small pin
holes, but still strong.
Liquid yellow with small
black particles hanging,
white particles sticking on
glass.
Grey color at bottom in
liquid F-85 immersed portion,
also softer at bottom. White
spots scattered on surface,
white line at interface
liquid yellow black colored,
with some fine white parti-
cles hanging.
Color changed to a darker
brown, material stron, F-85
and oil light brown, very
few suspended fine fibers.
Very few brown spots at
bottom, more yellow colored
material, slightly softer,
oil and F-85 light brown.
1. Neither Neoprene nor Nitrel Rubber should be used in the presence of
F-85 liquid and oil at 250°F.
2. SP-1 Polyimide may be used in the system at 250°F but preferably a
lower temperature in the presence of F-85 liquid and oil. It
showed about 0.44% swelling.
3. High temperature Polyamide DFS-20 may be used in the system at 250°F
or a lower temperature in the presence of F-85 liquid and oil. It
showed about 1.1% swelling with very light softening.
'Based on personal correspondence between Luco R. DiNanno,
Development Engineer for Thermo Electron, Corp, and writer,
September 13, 1972.
LEAR MOTORS CORPORATION
20
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Results of Material Compatibility
o
Tests Performed by Thermo Electron Corp.
Test Conditions:
Solution - Fluorine! 85 and lubricating oil 10 to 1 ratio
Temperature - 250°F
Duration - 17 days
Material Visual Observation
Dow Corning, LS53, The rubber was much softer, lightly attack at
Fluorosilicone Rubber bottom in liquid immersed portion, brownish
(-2" x 0.07" O.D.) material was sticking on glass and liquid
F-85 turned to very light brown.
Dow Corning LS63, The rubber was much softer, lightly attack in
Fluorosilicone Rubber liquid immersed portion. F-85 turned very
(1.5" x 0.1" O.D.) light brown.
Parker No. S455-7 The rubber was lightly softer, no apparent
Silicon Rubber change, F-85 turned light brown.
(2" x 0.1" O.D.)
RECOMMENDATIONS:
Silicone Rubber - Parker No. S455-7 is recommended to be used in the system
at temperature not exceeding 250°F in the presence of F-85 solution and air,
Based on correspondence between Dyer Kenney, Contract
Project Officer for Environmental Protection Agency, and writer
October, 1972.
LEAR MOTORS CORPORATION
21
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Material Compatibility Information on Elastomers Obtained from the Fluid
Manufacturer - Halocarbon Products Corporation
Test Conditions:
Solution - Fluorinol 85
Temperature - 284°F
Duration 7 days
Material % Height Change % Thickness Change
Ethylene-Propylene Rubber 1.3 to 2.6 1.1 to 1.5
Silicone Rubber 4.7 to 11 2.6 to 3.4
Neoprene 15 to 16 5.2 to 10
Pure Gum & Polyisoprene 20 to 46 8.8 to 16
Flurosilicone Rubber 1.6 to 49 -23 to 18
Viton A 34 to 54 13 to 15
Butyl 16 7.0
Completely Unsatisfactory: Buna N, Buna S and Hypalon.
3Based on correspondence between Mr. Rex Conner, Halocarbon
Products Corporation and writer, August, 1972.
LEAR MOTORS CORPORATION
22
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Results of Material Compatibility Tests
Performed by Aerojet Liquid Rocket Co.
Test Conditions:
Solution -
Temperature -
Duration -
AEF-78 (A.LRC working fluid)
250°F
150 hours
LMC Candidate Materials
Neoprene (Diaphragm. Stock)
Delrin (Dupont)
Vespel SP-1 Polyimide (Dupont)
Vespel SP-21 Polyimide (Dupont)
Polyamide DFS-21, Experimental (Dupont)
Nitrel (Diaphragm Stock)
Viton (Diaphragm Stock)
Polyamide DFS-20, experimental (Dupont)_
Natural Rubber (A.B. Boyd)
Silicone
Polyurethane (Newage Industries)_
Test Results
_Marginal
_Not Acceptable
Good
Good
Good
_Not Acceptable
_Marginal
Good
_Not Acceptable
Good
_Marginal
4Based on telephone conversation between A.H. Kreeger,
Manager Automotive Rankine Program, Aerojet Liquid Rocket Co. and
writer, November, 1972.
LEAR MOTORS CORPORATION
23
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Results of Elastomer Material Compatibility Tests
Performed by Aerojet Liquid Rocket Co. 5
Test Conditions:
Solution -
Temperature -
Duration
AEF-78
250°F
Long Term
Elastomer
Silicon Rubber (Dow Corning L-53)
Silicon Rubber (Dow Corning L-63)
Silicon Rubber (Parker HS 455-7)_
Florosilicon Rubber.
Chloroprene Rubber
Polysulfide (Thiokol Chemical Corp.)
Test Results
Good
Good
Good
_Not Acceptable
Good
Good
5Based on telephone conversation between A.H. Kreeger,
Manager Automotive Rankine Program, Aerojet Liquid Rocket Co. and
writer, September, 1972.
LEAR MOTORS CORPORATION
24
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CANDIDATE MATERIALS FOR SYSTEM
CONTRACTOR LMC PROPOSED FEEDPUMPS
Component
Manifold
(Inlet & Outlet)
Valve Plate
Outlet Valve
Inlet Valve
Valve Spring
(Inlet & Outlet)
Seals
(Enclosed & Static)
Diaphragm Seal
Materials for Working
SES
Cast 356 Aluminum
Stainless Steel
Type 303
Aluminum 6061-T6
Aluminum 6061-T6
Stainless Steel
Type 804
Nitrile Rubber
"Hydrin" Rubber
Fluid Section of Feedpump
ALRC TECO
Cast 356 Aluminum Cast 356 Aluminum
Stainless Steel
Type 303
Aluminum 6061-T6
Aluminum 6061-T6
Stainless Steel
Type 804
Silicone Rubber
Stainless Steel
Type 303
Aluminum 6061-T6
Aluminum 6061-T6
Stainless Steel
Type 804
Silicone Rubber
l.Silicone Rubber* Silicone Rubber*
2. Polysulfide Rubber*
Material for1 Oil Lubricate Section of Feedpump
Feedpump Housing
Bearings
(Drive Shaft)
Drive Shaft
Pistons
Bearings (Piston)
Cylinders
Seals
1. Cast Ductile Iron
2. Cast Aluminum
356-T6**
1. Cast Ductile Iron 1,
2. Cast Aluminum 2,
356-T6**
Cast Ductile Iron
Cast Aluminum
356-T6**
Steel (Anti-Friction) Steel (Anti-Friction) Steel (Anti-Friction)
Carborized 4620 Steel
Carborized 1117 Steel
Aluminum Bronze
Cast Nodular Iron
Buna "N" Rubber
Carborized 4620 Steel Carborized 4620 Steel
Carborized 1117 Steel Carborized 1117 Steel
Aluminum Bronze Aluminum Bronze
Cast Nodular Iron Cast Nodular Iron
Buna "N" Rubber Buna "N" Rubber
* Preliminary selection based on limited material compatibility study,
** Additional stress analysis required.
TABLE 3
-------
STEAM ENGINE SYSTEMS TECHNICAL REQUIREMENTS AND
LEAR MOTORS CORP. APPROACH
VAPOR GENERATOR FEEDPUMP
FOR RANKINE CYCLE AUTOMOTIVE
PROPULSION SYSTEM
EPA CONTRACT NUMBER 68-01-0437
December 1972
LEAR MOTORS CORPORATION
-------
STEAM ENGINE SYSTEMS
PUMP PERFORMANCE
TECHNICAL REQUIREMENTS
1. Expander Speed The speed of the reciprocating expander during
operation will vary from a minimum of 300 rpm to a maximum of
2500 rpm.
2. Flow The flow range shall be from 0 to 2.5 gpm. Maximum system
flow (2.5 GPM) shall occur at 40 percent of maximum expander speed
The feedpump shall be capable of modulating upon command from the
propulsion control system to satisfy any flow condition within the
the operating range specified. The feedpump shall be capable of
operating with no inlet flow for periods up to one minute without
damage.
3. Discharge Pressure The feedpump shall be capable of delivering
flow as specified, while discharging to a pressure of 1200 psia.
The discharge pressure shall be stable with no high frequency
oscillations in excess of 25 psia.
4. Efficiency The feedpump mechanical efficiency shall be 70% or
greater over the flow range from 30% to 80% of maximum design
flow. The mechanical efficiency shall be 50% or greater at 10%
of maximum design flow.
5. Fluid The working fluid for this system will be demineralized
water.
TECHNICAL APPROACH
The estimated performance curves, on the following page, demonstrate
how the proposed LMC feedpump would meet the SES technical requirements
shown above. This estimate was obtained by extrapolating actual LMC
feedpump data.
The maximum pressure ripple requirement is met by utilizing an odd
number of cylinders which are sized so that the instantaneous total flow of
the pump for any given crank angle is as smooth as possible.
Additional information regarding the LMC technical approach to the SES
feedpump performance requirements may be found in the technical discussions
section of this report.
LEAR MOTORS CORPORATION
27
-------
20
30
40 50 60
SPEED -' PER CENT
70
80
90
100
a
o
\
o
fa
Full Displacement Mech.
ESTIMATED FEEDWATER PUMP PERFORMANCE
EPA Contract No. 68-01-0437
System Contractor-Steam Engines Systems Corp.
Conditions:
Outlet Pressure .... 1200 PSIG
Suction Condition ... 5 PSI Min. N.P.S.H.
Fluid Temp. .... 160-250°F
O System Max. Flow -
Low Speed Corner Requirement
40 50 60 70
EXPANDER SPEED - PER CENT
80
90
100
90
80
70
O
z
w
M
O
60 £
w
50
40
O
30
20
707»
Mech.
EFF.
507«
Mech.
EFF.
100
240 480 720 960 1200 1440 1680 1920 2160 2400
PUMP SPEED ^ RPM
500
1000 1500
EXPANDER SPEED - RPM
2000
2500
FIGURE 7
28
-------
STEAM ENGINE SYSTEMS
PUMP INLET ENVELOPE
TECHNICAL REQUIREMENTS
1. Inlet Pressure The minimum pressure at the pump inlet valve
during start-up maybe as low as 0.09 psia. During system
operation, the inlet pressure may vary from a minimum of 7 psia
to a maximum of 50 psia.
2. Net Positive Suction Head The net positive suction head required
by the feedpump shall be minimized so that the pump can operate
without cavitating under low liquid head conditions without the
necessity of a boost pump.
3. Temperature Range During system operation, the temperature of
the working fluid may vary from 180°F to 250°F. At system
start-up the temperature of the working fluid may vary from 32°F
to 275°F.
4. Temperature Transients The feedpump shall stand feedwater
temperature transients of 3°F per second for periods of 10 seconds
without cavitating.
5. Booster Pump A booster pump for providing the required net
positive suction head to the feedpump shall be considered only
if trade-off studies conducted by the contractor reveal that the
utilization of a boost pump will simplify the feedpump design
sufficiently to offset the additional cost, weight and power
consumption required by the boost pump.
TECHNICAL APPROACH
The estimated pump inlet envelope on the following page shows the
Lear pump capability while operating at the 85% to 90% volumetric
efficiency level. The N.P.S.H. values shown are taken from actual data.
RECOMMENDATIONS
Due to the inherent lower N.P.S.H. characteristics of a centrifugal
pump and its ability to handle large quantities of entrained vapor, a
separate centrifugal boost pump is recommended for this system. The size
and characteristics of this pump will require a trade-off study of the
system condenser capability and the amount of sub-cooling allowable before
significant decreases in cycle efficiency occur.
LEAR MOTORS CORPORATION
29
-------
112.5
102.5-
92.5-
82.5-
100
90
80
00
ESTIMATED FEED PUMP INLET ENVELOPE
Fluid - Water
Conditions - 5000 Altitude
System Contractor-Steam Engine Systems
Normal
'Operating
Range
\ \l \
Open Pot Boiling Point of
Water @ 5000 Ft. ALT.
(12.5 PSIA @ 204°F Nominal)
20 I 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320
32
TEMPERATURE - °F
-------
STEAM ENGINE SYSTEMS
PUMP DRIVE
TECHNICAL REQUIREMENTS
1. Drive Mechanism The feedpump shall be mechanically driven with
power taken from the expander shaft or gearbox. The feedpump
shall provide the total range of required flow and pressure with
the expander operation at any speed within its specified speed
range. The non-linear relationship between expander speed and
required feedpump flow and pressure shall be accommodated by
variable drive mechanism characteristics and/or variable feedpump
and drive mechanism should be capable of being mounted in the
power plant as required by the system contractor.
TECHNICAL APPROACH
An outline drawing of the proposed Lear Motors Pump is shown on the
following page. The pump has variable displacement capability and can be
directly driven by the expander. Pump to expander speed ratio and interface
are not firm and will have to be worked out between Lear Motors and the
system contractor.
Pump physical size is based on the contracts pump performance
requirements, i.e. flow rate, and any change in the design flow rate will
directly affect pumps physical size and weight.
LEAR MOTORS CORPORATION
31
-------
OUTLINE DWG.,
PUMP -SCS/
-------
STEAM ENGINE SYSTEMS
GENERAL REQUIREMENTS
TECHNICAL REQUIREMENTS
1. Vehicle Design Goals Where applicable, "Vehicle Design Goals-
Six Passenger Automobile", shall be used as a guide for the design
requirements.
2. Materials All materials utilized in the construction of the
feedpump shall be corrosive resistant in a water/air environment.
3. Lubrication Any lubricants that may be used within the feedpump
and its drive mechanism shall not mix with or contaminate the
working fluid. The lubricant shall be the same as that used in
the expander.
4. Leakage There shall be no external leakage from the feedpump and
its drive mechanism. The unit shall be capable of being
hermetically sealed.
5. Working Fluid Drainage The feedpump shall be designed such that
all working fluid within the pump will drain back out of the
inlet side of the pump into the system sump at shutdown. Care
should be taken to assure that all pockets of fluid are adequately
drained to prevent damage due to freezing.
TECHNICAL APPROACH
The Lear Motors pump design, with its flexible diaphragm seal provides
inherent hermetic sealing of working fluid from the air and lubricated
section of the pump.
Working fluid drainage requirement will be met by unseating the inlet
valves at system shutdown allowing the fluid in each chamber to drain back
to the inlet manifold. This approach would not degrade the pumps
performance and would be integral to the pump.
Materials used for the construction of the proposed SES feedpump are
shown in Table 3. The material used for the pumps flexible sealing member
can be constructed from almost any elastometer which can meet the temperature
requirements and is compatible with the working fluid.
LEAR MOTORS CORPORATION
33
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AEROJET LIQUID ROCKET COMPANY TECHNICAL REQUIREMENTS AND
LEAR MOTORS CORP. APPROACH
VAPOR GENERATOR FEEDPUMP
FOR RANKINE CYCLE AUTOMOTIVE
PROPULSION SYSTEM
EPA CONTRACT NUMBER 68-01-0437
DECEMBER 1972
LEAR MOTORS CORPORATION
34
-------
AEROJET LIQUID ROCKET COMPANY
PUMP PERFORMANCE
TECHNICAL REQUIREMENTS
1. Speed Range The speed of the turbine expander will vary from a
minimum of 16,800 rpm to a maximum of 31,200 rpm. This same
speed ratio (1.85:1) will be available from the expander gearbox,
if required.
2. Flow The feedpump and its drive mechanism shall be capable of
delivering a constant flow of organic fluid from a minimum of
0.5 gpm to a maximum of 28 gpm at a discharge pressure from 650
psia to 1100 psia and at any given expander speed within the range
specified. Maximum system flow (28 gpm) shall occur at 59 percent
maximum expander speed.
3. Discharge Pressure The feedpump shall be capable of delivering
flow as specified while discharging to a pressure of 1100 psia.
The discharge pressure shall be stable with no high frequency
oscillations in excess of 25 psi.
4. Efficiency The feedpump mechanical efficiency shall be 70% or
greater over the flow range from 30% of maximum design flow to
80% of maximum design flow. The mechanical efficiency shall be
50% or greater at 10% of maximum design flow.
5. Fluid The working fluid will be a non-corrosive organic fluid
with a density of approximately 100 Ibs/ft^.
TECHNICAL APPROACH
The estimated performance curves, on the following page, demonstrate
how the proposed LMC feedpump would meet the ALRC technical requirements
shown above. This estimate was obtained by extrapolating actual LMC
feedpump data.
The maximum pressure ripple requirement is met by utilizing an odd
number of cylinders which are sized so that the instantaneous total flow
of the pump for any given crank angle is as smooth as possible.
Additional information regarding the LMC technical approach to the
ALRC feedpump performance requirements may be found in the technical
discussions section of this report.
LEAR MOTORS CORPORATION
35
-------
<4U
40 50 60
SPEED -" PER CENT
70
80
90
LOO
o
\
Cn
(Xc
S
PL,
52
48
44
40
36
32
28
24
20
16.
12
8
4
0"
Displacement Mech
ESTIMATED FEEDWATER PUMP
PERFORMANCE
EPA CONTRACT NO. 68-01-0437
System Contractor-
Aerojet Liquid Rocket Co.
Conditions:
Outlet Pressure - 1000 PSIG
Suction
Condition - 8 PSI Min.N.P.S.H.
Fluid Temp - 160-250° F
O System Max. Flow -
Low Speed Corner Requirement
20
28 GPM=1007.
8 GPM
4 GPMX
30 40 50 60 70
PUMP & EXPANDER SPEED -- PER CENT
80
100
90
80
70
60
50
40
30
20
z
w
707.
Mech.
EFF.
507«
Mech.
EFF.
90
100
0
0
200
3.1
400
6.2
600 800 1000 1200 1400
PUMP SPEED ^ RPM
9^4 12.5" is'. 6 18.6 2l'.8
EXPANDER SPEED x 10.3"^-RPM
1600
25.0
1800
2000
28.1 31.2
FIGURE 10
36
-------
AEROJET LIQUID ROCKET COMPANY
PUMP INLET ENVELOPE
TECHNICAL REQUIREMENTS
1. Inlet Pressure The minimum pressure at the pump inlet valve
during start-up may be as low as 1.0 psia. During system
operation, the inlet pressure may vary from a minimum of 10 psia
to a maximum of 40 psia.
2. Net Positive Suction Head The minimum liquid head at the pump
inlet is 7 inches. Care must be taken to assure cavitation does
not occur during start-up or during abnormal operating conditions
resulting in a loss of condenser sub-cooling.
3. Temperature Range During system operation, the temperature of
the working fluid may vary from 160°F to 250°F. At start-up the
temperature of the working fluid may vary from -40°F to 275°F.
4. Booster Pump A booster pump for providing the required net
positive suction head to the feedpump shall be considered only
if trade-off studies conducted by the contractor reveal that the
utilization of a boost pump will simplify the feedpump design
sufficiently to offset the additional cost, weight,and power
consumption required by the boost pump.
TECHNICAL APPROACH
The estimated pump inlet envelope on the following page shows the
Lear pump capability while operating at the 85% to 90% volumetric
efficiency level. The N.P.S.H. values shown are taken from actual data
which has been corrected to meet the system contractors fluid character-
istics.
RECOMMENDATIONS
Due to the inherent lower N.P.S.H. characteristics of a centrifugal
pump and its ability to handle large quantities of entrained vapor, a
separate centrifugal boost pump is recommended for this system. The size
and characteristics of this pump will require a trade-off study of the
systems condenser capability and the amount of sub-cooling allowable
before significant decreases in cycle efficiency occur.
LEAR MOTORS CORPORATION
37
-------
114.7
104.7-
94.7-
84.7-
100
90
80
70
60
50
40
ESTIMATED FEED PUMP INLET ENVELOPE
Fluid- AEF-78
Specific Gravity = 1.793 @72°F
System Contractor - Aerojet Liquid Rocket Co.
Open Pot Boiling Point
For AEF-78
(14.7 PSIA @ 189°F)
-20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
TEMPERATURE °F
CO
Co
-------
AEROJET LIQUID ROCKET COMPANY
PUMP DRIVE AND CONTROL
TECHNICAL REQUIREMENTS
1. Drive Mechanism The feedpump shall be mechanically driven with
power taken from the expander shaft or gearbox. The feedpump
shall provide the total range of required flow and pressure with
the expander operation at any speed within-its specified speed
range. The non-linear relationship between expander speed and
required feedpump flow and pressure shall be accommodated by
variable drive mechanism characteristics and/or variable feedpump
capacity characteristics. The feedpump and drive mechanism should
be capable of being mounted in the power plant as required by the
system contractor.
2. Control Movement of the vehicle accelerator pedal will provide
a mechanical input signal to the feedpump for flow modulation.
TECHNICAL APPROACH
An outline drawing of the proposed Lear Motors pump is shown on the
following page. The pump has variable displacement capability and can be
directly driven by the expander. Pump to expander speed ratio and
interface are not firm and will have to be worked out between Lear Motors
and the system contractor.
Pump physical size is based on the contract pump performance require-
ments, i.e. flow rate, and any change in the design flow rate will directly
affect pump physical size and weight.
LEAR MOTORS CORPORATION
39
-------
O
-------
AEROJET LIQUID ROCKET COMPANY
GENERAL REQUIREMENTS
TECHNICAL REQUIREMENTS
1. Vehicle Design Goals Where applicable, "Vehicle Design Goals-
Six Passenger Automobile", shall be used as a guide for the
design requirements.
2. Leakage There shall be no external leakage from the feedpump
and its drive mechanism. The unit shall be capable of being
hermetically sealed.
3. Lubrication Any lubricants that may be used within the feedpump
and its drive mechanism shall not mix or contaminate the
working fluid. The lubricant shall be the same as that used in
the expander.
4. Materials Compatibility All materials utilized in the construction
of the feedpump shall not corrode or otherwise chemically react
with the fluid in any manner.
TECHNICAL APPROACH
The Lear Motors pump design with its flexible diaphragm seal provides
inherent hermetic sealing of working fluid from the air and lubricated
section of the pump.
Materials used for the construction of the proposed ALRC feedpump are
shown in Table 3. The material used for the pumps flexible sealing member
can be constructed from elastomers which meet the temperature requirements
and is compatible with the working fluid.
LEAR MOTORS CORPORATION
41
-------
THERMO ELECTRON CORPORATION TECHNICAL REQUIREMENTS AND
LEAR MOTORS CORP. APPROACH
VAPOR GENERATOR FEEDPUMP
FOR RANKINE CYCLE AUTOMOTIVE
PROPULSION SYSTEM
EPA CONTRACT NUMBER 68-01-0437
DECEMBER 1972
LEAR MOTORS CORPORATION
42
-------
THERMO ELECTRON CORPORATION
PUMP PERFORMANCE
TECHNICAL REQUIREMENTS
1. Expander Speed Range The operating speed range of the recipro-
cating expander will vary from a minimum of 300 rpm to a maximum
of 1800 rpm.
2. Flow Flow range shall be from 0 to 17 gpm. Maximum system flow
(17 gpm) shall occur at 45 percent maximum expander speed. The
feedpump shall be capable of modulating upon command from the
propulsion control system to satisfy any flow condition within the
operating range specified.
3. Discharge Pressure The feedpump shall be capable of operating at
a constant discharge pressure of 1000 psia while modulating flow
over the range specified. The discharge pressure shall be stable
with no high frequency oscillations in excess of 25 psi.
4. Efficiency The feedpump mechanical efficiency shall be 70% or
greater over the flow range from 30% of maximum design flow to
80% of maximum design flow. The mechanical efficiency shall be
50% or greater at 10% of maximum design flow.
5. Fluid The working fluid will be a non-corrosive organic fluid
with a density of approximately 80 lbs/ft3.
TECHNICAL APPROACH
The estimated performance curves, on the following page, demonstrate
how the proposed LMC feedpump would meet the TECO technical requirements
shown above. This estimate was obtained by extrapolating actual LMC
feedpump data.
The maximum pressure ripple requirement is met by utilizing an odd
number of cylinders which are sized so that the instantaneous total flow
of the pump for any given crank angle is as smooth as possible.
Additional information regarding the LMC technical approach to the
TECO feedpump performance requirements may be found in the technical
discussions section of this report.
LEAR MOTORS CORPORATION
43
-------
20
30
40 50 60
PUMP SPEED -' PER CENT
70
80
90
100
40
36
32
s
PM
o
1
fa
Pu
a
CM
28
24
20
16
12
Full Displacement Mech. EFF.
ESTIMATED FEEDWATER PUMP PERFORMANCE
EPA Contract No. 68-01 0437
System contractor - Thermo Electron Corp.
Conditions:
Outlet Pressure . . . 1000 PSIG
Suction Condition . . 7 PSI Min, N.P.S.H.
Fluid Temp 160-250°F
O System Max. Flow -
Low Speed Corner Requirement
20
30 40 50 60 "70
PUMP & EXPANDER SPEED <- Per Cent
80
"90
100
90
6-S
80 I
70
w
60
fa
50 w
40
30 2
a
w
20 33
10
70%
Mech.
Eff
507,
Mech.
Eff
100
0
0
200
180
400
360
600
540
800 1000 1200
PUMP SPhclD ^ RPM
720 900 1000
EXPANDER SPEED ^ RPM
1400
1260
1600
1440
i
1800 2000
1620 1800
FIGURE 13
44
-------
THERMO ELECTRON CORPORATION
PUMP INLET ENVELOPE
TECHNICAL REQUIREMENTS
1. Inlet Pressure In the Rankine cycle system, the feedpump inlet
pressure is determined by the condensing pressure and the
elevation of the pump relative to the condenser. At system
start-up, prior to the time when condenser pressure builds up due
to heat load, the inlet pressure at the pump may be no greater
than 0.5 psia. During operation the inlet pressure may vary
from a minimum of 5 psia to a maximum of 90 psia.
2. Net Positive Suction Head The minimum liquid head at the pump
inlet is 10 inches. Care must be taken to assure cavitation does
not occur during start-up or during abnormal operating conditions
resulting in a loss of condenser sub-cooling.
3. Temperature Range During system operation, the temperature of
the working fluid may vary from 160°F to 250°F. At start-up
the temperature of the working fluid may vary from -40°F to 275°F.
4. Booster Pump A booster pump for providing the required net
positive suction head to the feedpump shall be considered only if
utilization of a boost pump will simplify the feedpump design
sufficiently to offset the additional cost, weight and power
consumption required by the boost pump.
TECHNICAL APPROACH
The estimated pump inlet envelope on the following page shows the
proposed LMC pump capability while operating at the 85% to 90% volumetric
efficiency level. The N.P.S.H. values shown are taken from actual data
which has been corrected to meet the TECO organic fluid characteristics.
Due to the inherent lower N.P.S.H. characteristics of a centrifugal
pump and its ability to handle large quantities of entrained vapor, a
separate centrifugal boost pump is recommended for this system. The size
and characteristics of this pump will require a trade-off study of the
system condenser capability and the amount of sub-cooling allowable before
significant decreases in cycle efficiency occur.
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114.7
104.7-
100
Normalv
Operating
Range \
ESTIMATED FEED PUMP INLET ENVELOPE
FLUID - Trifluoroethanol
(Fluorinol-85
SPECIFIC GRAVITY = 1.368 @72~F
SYSTEM CONTRACTOR - Thermo
Electron Corp.
Open Pot Boiling Point
Fluorinol - 85
(14.7 PSIA @ 166
-20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 28.0 300
TEMPERATURE -F
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THERMO ELECTRON CORPORATION
PUMP DRIVE AND CONTROL
TECHNICAL REQUIREMENTS
1. Drive Mechanism The feedpump shall be mechanically driven with
power taken from the expander shaft or gearbox. The feedpump
shall provide the total range of required flow and pressure with
the expander operation at any speed within its specified speed
range. The non-linear relationship between expander speed and
required feedpump flow and pressure shall be accommodated by
variable drive mechanism characteristics and/or variable feedpump
capacity characteristics. The feedpump and drive mechanism should
be capable of being mounted in the powerplant as required by the
system contractor.
2. Control Movement of the accelerator pedal will provide a
mechanical input signal to the feedpump for flow modulation.
TECHNICAL APPROACH
An outline drawing of the proposed Lear Motors pump is shown on the
following page. The pump has variable displacement capability and can be
directly driven by the expander. Pump to expander speed ratio and inter-
face are not firm and will have to be worked out between Lear Motors and
the system contractor.
Pump physical size is based on the contracts pump performance
requirements, i.e. flow rate, and any change in the design flow rate will
directly affect pump physical size and weight.
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THERMO ELECTRON CORPORATION
GENERAL REQUIREMENTS
TECHNICAL REQUIREMENTS
1. Vehicle Design Goals Where applicable "Vehicle Design Goals-
Six Passenger Automobile", shall be used as a guide for the
design requirements.
2. Leakage There shall be no external leakage from the feedpump
and its drive mechanism. The unit shall be capable of being
hermetically sealed.
3. Lubrication Any lubricants that may be used within the feedpump
and its drive mechanism shall not mix with or contaminate the
working fluid. The lubricant shall be the same as that used in
the expander.
4. Materials Compatibility All materials utilized in the
construction of the feedpump shall not corrode or otherwise
chemically react with the fluid in any manner.
TECHNICAL APPROACH
The Lear Motors pumo design with its flexible diaphragm seal provides
inherent hermetic sealing of working fluid from the air and lubricated
section of the pump.
Materials used for the construction of the proposed TECO feedpump are
shown in Table 3. The material used for the pumps flexible sealing member
can be constructed from most elastomers which meet the temperature
requirements and is compatible with the working fluid.
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V CONCLUSION
Based on the results of this study and the past experience of Lear
Motors in the development of Rankine Cycle Automotive Propulsion Systems,
a radial piston, variable displacement feedpump design was selected to
satisfy the requirements of the three Rankine Cycle System Contractors.
The proposed feedpumps hermetically seal the working fluid from
the atmosphere and lubricating oil by utilization of a diaphragm seal.
all of the highly stressed moving parts in the pump are oil lubricated
allowing conventional, low cost materials to be used throughout its
construction.
Three separate pumps were determined necessary because of the vast
difference in system flow requirements. Due to the high flow at low
speed requirements of the two organic systems, these pumps will be
physically larger than the pump designed for the water base contractor.
Ductile iron was selected as the material of construction for the
pump housing. A detailed stress analysis of an aluminum pump housing as
a means of reducing weight is recommended. Also, any reduction in the
high flow - low speed requirement of the organic systems would allow a
significant reduction in size and weight.
Projected feedpump performance will contribute to high cycle
efficiency; full displacement mechanical efficiencies from 85 to 90
percent are feasible.
It is recommended that an externally driven boost pump be used with
the proposed feedpumps to assure reliable operation at all system
operating conditions. A centrifugal type boost pump was selected because
of its capability for pumping at very low NPSH values.
A major effort was directed toward finding elastimers which were
compatible with the two organic fluids. Several candidates were found
acceptable for operation at 250° or lower. Additional investigations are
required to determine the long term effects of the fluids on elastomers.
The Lear Motors proposed feedpumps will satisfy the requirements
of the three Rankine Cycle Automobile Power Systems with one exception;
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the low flow - high speed region of the estimated pump performances
does not fully meet the system contractors mechanical efficiency
requirements.
The knowledge gained from this study and the background stemming
from our four year feedpump development program are incorporated in
these proposed pump designs. Reliable operation with a minimum develop-
ment time is assured as this basic type of pump has been well developed
in the Lear Motor Rankine Cycle Systems.
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REFERENCES
Baumeister, Theodore and Lionel S. Marks, ed., Mechanical Engineer's
Handbook, New York: McGraw-Hill, 1958.
Binder, R.C., Fluid Mechanics, Englewood Cliffs, New Jersey:
Prentice-Hall, 1955.
Erast, Walter, Oil Hydraulic Power and Its Industrial Applications,
New York: McGraw-Hill, 1960.
Gartmann, Hans, ed., Del-aval Engineering Handbook, New York:
McGraw-Hill, 1970.
Tuve, G.L. and L.C. Domholdt, Engineering Experimentation, New York:
McGraw-Hill, 1966.
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APPENDIX A
LEAR MOTORS PUMP STANDARDS
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7001-3401
July 26, 1972
PUMP STANDARDS
LEAR MOTORS CORPORATION
PUMP TEST CODE
I. Object
This code establishes a procedure for conducting and
reporting tests of Rankine Cycle feedwater and condensate
pumps. It is intended that the tests shall be made and reported
by qualified personnel trained in the proper application and
use of the various instruments and methods involved.
II. Records
Complete records shal'l be kept of all information relevant
to a test. The serial number, type, size, or other means of
identification of each pump tested shall be recorded in order
that mistakes in identity be avoided.
III. Measurements
The essential measurements for test of feedwater and
condensate pumps are:
1. Flow
2. Outlet Pressure
3. Suction Pressure or Vacuum
4. Temperature of pumped fluid
5. Temperature of pump
6. Power input to pump
7. Speed
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IV. Flow Measurement
The rate of flow shall be expressed in gallons per minute
(gpm) and be measured with calibrated rotameter compatible
with pumped fluid.
V. Outlet Pressure Measurement
Head or outlet pressure shall be designated in pounds per
square inch gage (psig). Measurement will be made with a
calibrate pressure gage of the proper range.
VI. Suction Pressure or Vacuum Measurement
Suction pressure shall be designated in pounds per
square inch absolute (psia). Suction vacuum conditions shall
be designated in inches of mercury (in. Hq). Measurement will
be made with a calibrated pressure gage or mercury manometer
of the proper range.
VII. Temperature Measurements
Temperature will be expressed in degrees fahrenheit (°F).
A calibrated thermometer with the proper range will be used.
VIII.Input Power Measurements
(a) Pump input horsepower may be determined by means of
transmission dynamometers, torsion dynamometers or calibrated
drivers.
(b) Transmission Dynamometers. When pump input horsepower
is to be determined by transmission dynamometers, the unloaded
and unlocked dynamometer must be properly balanced prior to
the test at the same speed at which the test is to be run and
the scales should be checked against standard weights. After
the test, the balance must be rechecked to assure that no change
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(b) Cont.
has taken place. In the event of an appreciable change,
the test shall be rerun. An accurate measurement of speed is
essential.
(c) Torsion Dynamometers. When pump input horsepower is to
be determined by torsion dynamometers, the unloaded dynamometer
shall be statically calibrated prior to the test by measuring
the angular deflection for a given torque, the tare reading
on the dynamometer scale being taken at rated speed with the
pump disconnected. After the test, the calibrations must be
rechecked to assure that no change has taken place. In the event
of an appreciable change, the test shall be rerun. An accurate
measurement'of speed is essential.
(d) Calibrated Drivers. When pump input horsepower is to be
determined by the use of a calibrated motor, the following shall
be applied:
1. All measurements of power input shall be made at the
terminals of the motor to exclude any line losses that may
occur between the switchboard and the driver itself.
Certified calibration curves of the motor must be obtained.
The calibration shall be conducted on the specific motor
in question, and not on an identical machine.
2. Such calibration curves must indicate the true input-
output value of motor efficiency and not some conventional
method of determinining an arbitrary efficiency.
3. When the pump is arranged with a speed changing device
between the driver and the pump, the input to the pump
shall be the actual output of the driving element less the
loss through the speed changing device. The value of
this loss shall be certified by the manufacturer of the
speed changing device.
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X. Measurement of Speed
(a) Measurement of speed shall be made by means of revolution
counters or tachometers.
(b) For speed measurements taken by means of a revolution
counter, the timing period shall be of sufficient length to
obtain a true average speed and the stopwatch used should be
checked against a standard timer.
(c) When a tachometer is used, it shall be calibrated against
a revolution counter before and after test. Tachometer readings
should be made at frequent intervals during each test point to
obtain an accurate measurement of average speed over the reading
period.
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PUMP RATING CRITERIA
I. Introduction
The following numbered paragraphs define the quantities
used to designate pumping applications.
II. Volume, Standard Units
(a) The standard unit of volume shall be the United States
gallon or the cubic foot. The standard U.S. gallon contains
231.0 cubic inches. One cubic foot equals 7.4805 gallons.
(b) The rate of flow shall be expressed in gallons per minute
(gpm), gallons per hour (gph).
(c) The specific weight of water at a temperature of 68°F
shall be taken as 62.3 Ib per cu ft. For other temperatures,
proper specific weight corrections should be made.
III. Pump Volumetric Efficiency (Symbol E )
The volumetric efficiency of a rotary pump is the ratio of
the actual pump capacity to the displacement, expressed in percent,
at the specified pumping conditions:
F = capacity „ lnn
v displacement
IV. Pump Input (Symbol bhp or ehp)
The unit of power input to pump is the horsepower.
1 horsepower = 550 foot-pounds per second
= 33,000 foot-pounds per minute
= 2545 Btu per hour
= .7457 kilowatts
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(a) The input horsepower (bhp) when measured by a transmission
or torsion dynamometer, is calculated from the following
formula:
bhp = 2 *
33,000
where
L = length of lever arm in feet
W = net weight in pounds
N = speed in rpm
IT = 3.1416
(b) The electrical horsepower input to an electric motor is
given by:
ehp = kw^Qr Volts X Amps
where
kw = kilowatt input.
(c) The input horsepower to a pump driven by an electric
motor is:
bhp = ehp X Em
where
E = true efficiency of motor.
V. Pump Output (Symbol whp)
(a) Pump output is the liquid horsepower delivered by the pump.
(b) The liquid horsepower is to be computed by the following
formula:
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pounds of liquid x Total head in
U(hn _ pumped per min. ft of liquid
W P 33,000
(c) If the capacity is expressed in gallons per minute (gpm)
the formula for liquid horsepower becomes:
,,hn gpm X (total head in feet) X sp gr
wnp " 3960
where:
sp gr = specific gravity of liquid referred to 68°F water,
weighing 62.3 Ib per cu ft.
(d) If the total head is expressed in pounds per square inch,
the formula for liquid horsepower, irrespective of specific
gravity of the liquid, becomes:
whp = gpm X (total head in psi)
17T4
VI. Mechanical Efficiency
(a) Pump mechanical efficiency (E ) is the ratio of the energy
delivered by the pump to the energy supplied to the pump
shaft; that is, the ratio of the liquid horsepower to the brake
horsepower expressed in percent:
100 or whP _
IUU or
_
p bhp ehp X Em
(b) Overall unit efficiency (EQ) is the ratio of the energy
delivered by the pump to the energy supplied to the input side
of the pump driver; that is, in the case of electric-driven
pumps, the ratio of the liquid horsepower to the electrical
horsepower input to the driver, expressed in percent:
E, •
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VII. NPSH Definition
NPSH (net positive suction head) is defined as the net
pressure absolute above vapor pressure at the pump inlet. In
pumping .liquids we are concerned with getting the liquid into
the pump in a liquid state (i.e. without vaporization).
Suction lift, friction losses, and entrance losses all conspire
to reduce net pressure and in some cases interfere with the
liquid getting into the pump in liquid phase.
It should be remembered that the boiling ooint of a liquid is
that point at which vapor pressure equals external pressure.
Whether this takes place in open or closed vessels there is
usually a vapor area in contact with the liquid and a liquid
level line. At boiling point the addition of heat or the lowering
of external pressure unbalances this equilibrium and results
in the vaporization of an amount of liquid.
Also to be considered is that centrifugal pumps are liquid
handling machines. Although pumps will handle up to 50%
entrained gas or vapor and will dispose of the air in suction
lines during priming cycle they are not efficient vapor handling
devices. Further,there is a great expansion of volume in the
conversion from liquid to vapor state which takes up the
inherent pump capacity.
Reduced capacity at low NPSH is an efficiency loss permitting
no revision of brake horsepower. Because of this'major
consideration of maintaining liquid state during the pumping
cycle it is essential to make an NPSH calculation in all
applications involving a liquid at or close to boiling point.
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NPSH CALCULATION
Three general cases may be considered in making an NPSH
calculation.
Case I - The liquid level of the supply is above the pump
centerline. This is termed static suction head.
Case II- The liquid level of the supply is below the pump
centerline. This is suction lift.
Case I is by far the most common in industrial applications.
Hot water or various other liquids are pumped out of a vessel
elevated above the pump. In such a case it is usually necessary
to consider only four elements in calculating NPSH.
CASE I
Fluid Level
Direction
Of Flow
WHERE:
hs = Static Suction Head (PSIG)
h = Vapor Pressure (PSIA)
ha = Atmospheric Pressure (PSIA)
hf = Friction Loss (PSIG)
In the range of capacities involving pumps (up to 250 GPM)
velocity head need not be considered.
Then in any Case I system the following formula applies:
hs + ha - (hvp + M = NPSH
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Case IA: The liquid is in a closed vessel in vacuum or pressure
systems. In this special case vapor pressure will equal atmo-
spheric pressure.
CASE IA
Vent
Direction
Of Flow
WHERE:
= Static Suction Head (PSIG)
= Vapor Pressure (PSIA)
h, = Atmospheric Pressure (PSIA)
a
hf = Friction Loss (PSIG)
vp
.'. hs - hf = NPSH
In planning piping for NPSH problems it is usually desirable to
increase the size of suction piping until friction loss in the
suction line is less than 6 in. of liquid head.
In such cases h-r may be disregarded in the application. The
formulae then becomes:
Case I:
Case IA:
ha - hvp = NPSH
hs = NPSH
In Case I NPSH is identical with static suction head when the liquid
is at boiling point and the suction piping is large enough to keep
total friction loss below 6 in. of liquid head.
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Case II can never involve liquids at boiling point since a
negative NPSH condition would result and vaporization would
take place. All cases of NPSH calculations involving suction
lift must also involve liquids below boiling point. With the
vapor pressure less than the atmospheric pressure the formula is
as follows:
CASE II
Discharge
Direction
of f1ow
—i-iii^^j— LI-— /—Foot Valve
WHERE:
= Static Suction Head (PSIG)
= Vapor Pressure (PSIA)
ha = Atmospheric Pressure (PSIA)
. = Friction Loss (PSIG)
vp
ha ' hvp - hs ' NPSH
Atmospheric pressure is then the only positive force in Case II
Both vapor pressure and suction lift are negative factors.
NOTE:
Static suction head (h ) for any fluid:
Inches of Head x Specific Gravity x .03613 = PSIG
Feet of Head x Specific Gravity x .4335 = PSIG
K*
Max K. Winkler
Reference: Standard of Hydraulic Inst.
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