United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development February 1993 EPA-600/S-93-0Q1
CEDA ENVIRONMENTAL
\/fcnr\ RESEARCH BRIEF
Thermo physics! Properties of HFE-125
N. Dean Smith
Thermophysical properties of HFE-125
(pentafluorodimethylether) suggest that it
could serve as an alternative non-ozone
depleting refrigerant for certain low
temperature applications. This Brief
presents the thermophysical properties of
HFE-125 (Tables 1-4) which have been
obtained by the Environmental Protection
Agency's Air and Energy Engineering Research
Laboratory.
Measured properties include boiling point,
freezing point, critical temperature, critical
density, heat of vaporization at the boiling
point, and liquid specific heat at 40°C. The
critical pressure was determined from the
critical temperature and critical density.
Liquid densities were measured at six
temperatures over the range of approximately
10 to 60°C and were calculated from below
the boiling point to the critical temperature
using a least squares fit of the measured data.
Vapor pressures were measured at 39
temperatures ranging from below the boiling
point to the critical temperature. Vapor
densities were not measured but were
calculated by a modified corresponding states
method using the measured critical
temperature, critical density, and boiling
point
All measured properties were determined
using 99.5 percent pure HFE-125 which was
obtained from a commercial source and
repurified. Freezing point, boiling point, and
critical temperature are considered accurate
to ±.Q.2°C. Vapor pressures measured from
below the boiling point up to the boiling point
are accurate to ±.0.5 kPa, and vapor
pressures measured above the boiling point
are accurate to ±3 kPa. The heat of
vaporization measured at the boiling point is
accurate to ±,0.1 kj/mol. Measured liquid
densities and the critical density are accurate
to within 2 percent, and the liquid specific
heat to within 3 percent.
Vapor densities for CFC-12 (difluoro-
dichloromethane) determined by the modified
corresponding states method were found to be
within 3 percent of literature values.
Therefore, this same accuracy Is assumed for
the calculated vapor densities of HFE-125.
Details regarding the methods utilized for
determining these properties are reported by
Beyerlein et al.1 Similar property data for
HFE-125 have also been reported by Salvi-
Narkhede et al.2

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TABLE 1. MEASURED PHYSICAL PROPERTIES OF HFE-125
Property
SI Units
English Units
Boiling Point (Tb)
-34.6°C
-30.3°F
Freezing Point
-1 56.1 °C
-249.0OF
Critical Temperature
80.7°C
177.3°F
Criticat Pressure*
3253 kPa
471.8 psia
Critical Density
584 kg/m3
36.4 lb/ft3
Heat of Vaporization @ Tb
181.2 kJ/kg
69.34 Btu/lb
¦liquid Specific Heat @ 40°C
1.327 kJ/ka K
0.3172 Btu/lb °F
* Critical pressure determined from critical temperature and critical density
TABLE 2. MEASURED LIQUID DENSITIES OF HFE-125
Temperature, °C (°F)
Liquid
Density, kg/m3 (lb/ft3) |
S.7 (49.5)
1362
(85.00) I
22.4 (72.3)
1298
(81.05)
32.1 (89.8)
1254
(78.32)
42.2 (108.0)
1196
(74.68)
51.4 (124.4)
1133
(70.72)
60.8 (141.5)
1051
(65.62)
TABLE 3. MEASURED VAPOR PRESSURES OF HFE-125
Temperature, °C (°F)
Vapor Pressure, kPa (psia)
-104.4 (-155.7)
0.83
(0.120)
-95.7 (-140.3)
1.53
(0.222)
-85.8 (-122.4)
4.20
(0.609) I
I -74.6 (-102.3)
10.16
(1 -474)
-73.4 (-100.1)
10.80
(1.566)
-65.3 (-85.5)
19.47
(2.823)
-63.4 (-82.1)
21.73
(3.152)
-55.6 (-68.1)
34.80
(5.047)
-54.6 (-66.3)
36.00
(5.221)
I -53.9 (-65.0)
38.40
(5.569)
-49.5 (-56.4)
49.73
(7.213)
-48.6 (-55.5)
50.73
(7.358)
-44.8 (-48.6)
61.72
(8.953)
-44.4 (-44.9)
63.46
(9.204)
-39.3 (-38.7)
80.53
(11.68)
-38.9 (-38.0)
83.06
(12.05)
1 -38.6 (-37.5)
83.99
(12.18)
-36.9 (-34.4)
90.53
(13.13)
-34.6 (-30.3)
100.9
(14.83)
-34.3 (-29.7)
102.3
(14.83)
-34.2 (-29.6)
102.7
(14.89)
(Continued)
2

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Table 3 Continued
Temperature, °C (°F)	Vapor Pressure, kPa (psia)
5.4 (41.7)
499.9 (72.50)
10.1 (50.2)
580.6 (84.21)
14.8 (58.6)
668.9 (97.02) I
20.0 (68,0)
776.6 (112.6) I
24.8 (76.6)
889.3 (129.0) I
30.4 (86.7)
1034 (150.0) I
34.7 (94.5)
1160 (168.2)
40.0 (104.0)
1327 (192.4)
45.3 (113.5)
1508 (218.8)
50.4 (122.7)
1703 (247.0)
54.9 (130.8)
1881 (272.8) 1
59.9 (139.8)
2100 (304.6) 1
I 65.9 (150.6)
2393 (347.1)
70.0 (158.0)
2610 (378.6)
74.8 (166.6)
2892 (419.5)
78.0 (172.4)
3087 (447.8) I
80.0 (176.0)
3203 (464.6) I
80.7 (177.3)
3253 (471.8) II
TABLE 4. CALCULATED UQUID DENSITY, VAPOR DENSITY, AND HEAT OF VAPORIZATION OF
HFE-125

Temperature
Liquid Density
Vapor Density
Heat of Vaporization

°C (°F)
kg/m
3 (lb/ft3)
kg/m3 (lb/ft3)
kJ/kg
(Btu/Ib)

-54.6 (-66.3)
1603
(100.1)
2.79 (0.174)
167.5
(72.06) 1

-50.6 (-59.1)
1590
(99.24)
3.44 (0.215)
166.2
(71,52)

-46.6 (-51.9)
1576
(98.39)
4.21 (0.263)
165.0
(70.98)

-42.6 (-44.7)
1562
(97.54)
5.11 (0.319)
163.7
(70.44)

38.6 (-37.5)
1549
(96.67)
6.16 (0.384)
162.5
(69.90)

-34.6 (-30.3)
1535
(95.80)
7,32 (0.457)
161.2
(69.34)

-30.0 (-22.0)
1518
(94.78)
8.94 (0.558)
158.6
(68.26) I

-25.4 (-13.7)
1502
(93.74)
10.83 (0,676)
156.1
(67.16) 1

-20.8 (-5.4)
1485
(92.68)
13.01 (0.812)
153.4
(66.02) |

-16.2 (2.9)
1467
(91.60)
15.53 (0.970)
150.7
(64.85)

¦11.5 (11.2)
1450
(90.50)
18.43 (1.150)
147.9
(63.65)

-6.9 (19.5)
1432
(89.37)
21.73 (1.356)
145.0
(62.41) I

-2.3 (27.8)
1413
(88.22)
25.49 (1.591)
142.1
(61.13) |

2.3 (36.1)
1394
(87.03)
29.75 (1.857)
139.0
(59,81) I

6.9 (44.4)
1375
(85.81)
34.58 (2,159)
135.8
(58.43)

11.5 (52.7)
1351
(84,37)
40.03 (2.499)
132.5
(57.01)

16.1 (61.0)
1333
(83.23)
46.19 (2.884)
129.0
(55.52) I

20.7 (69.3)
1313
(81.96)
53.15 (3.318)
125.4
(53.96) 1

25.4 (77.6)
1291
(80.58)
61.03 (3.810)
121.6
(52.33) I

30,0 (85.9)
1267
(79.07)
69.94 (4.366)
117.6
(50.62)

34.6 (94.2)
1240
(77.44)
80.08 (4.999)
113.4
(48.80)

39.2 (102.6)
1212
(75.68)
91.67 (5.723)
109.0
(46.87)
(Continued)
3

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Table 4 Continued
Temperature
Liquid Density
Vapor Density
Heat of Vaporization I
°C («F)
kg/m3 (lb/ft3)
kg/m3 (lb/ft3)
kJ/kg (Btu/ib) |
43.8 (110.8)
1182 (73.81)
105.0 (6.554)
104.1 (44.80)
48.4 (119.2)
1150 (71.81)
120.4 (7.518)
98.96 (42.56)
I 53,0 (127.4)
1116 (69.69)
138.6 (8.649)
93.22 (40.12)
1 S7.6 (135.8)
1080 (67.45)
160.1 (9.994)
86.97 (37.41)
62.2 (144.0)
1046 (65.29)
186.2 (11.62)
79.84 (34.35)
66.9 (152.4)
999 (62.36)
218.4 (13.63)
71.46 (30.76)
71.5 (160.7)
943 (58.87)
259.4 (16.20)
61.17 (26.33)
76.1 (169.0)
874 (54.54)
314.1 (19.61)
46.90 (20,19)
80.7 (177.3)
584 (36.43)
583.6 (36.43)
0.00 (0,00)
Equation for liquid density In kg/m3 is;
D, = 1388.6 + (-2.698E+00)C + (-4.597E-02)C2	C - temperature In °C
Range is 9.7 to 60.8°C.
Equation for liquid density in lb/ft3 Is;
D| = 88.777 + {-3.687E-02)F + {-8.857E-04)F2	f = temperature in °F
Range is 49.5 to 141.5°F.
Vapor density was calculated by a modified corresponding states method.1.3
Heat of vaporization was calculated by the method of Thek and StieH with the Viswanath
modification.5
References:
1.	Beyerlein, A. L., et al., "Physical Properties of Fluorinated Propane and Butane
Derivatives as Alternative Refrigerants," Technical Paper No. 3858, presented at
American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)
Winter Meeting, Chicago, January 23-27, 1993.
2.	Salvi-Narkhede, M., et al., "Vapor Pressures, Liquid Molar Volumes, Vapor Nonideality,
and Critical Properties of Some Partially Fluorinated Ethers {CF3OCF2CF2H, CF3OGF2H,
and CF3OCH3), Some Perfluoroethers (CF3OCF2OCF3, C-CF2OCF2OCF2, and
C-CF2CF2CF2O), and CHFgir and CF3CFHCF3," J. Chem. Thermodynamics, 1993 (in
press).
3.	Reid, R. C„ J. M. Prausnitz, and B. E. Poling, The Properties of Gases and Liquids. 4th
ed., McGraw-Hill, New York, 1984.
4.	Thek, R. E, and L. I. Stiel, "A New Reduced Vapor Pressure Equation," AlChE J„ 12, 599
(1966); Addendum, 13., 626 (1967).
5.	Viswanath, D. S. and N. R. Kuloor, "On a Generalized Watson's Relation for Latent Heat of
Vaporization," Can. J. Chem. Eng., 29, 1967.
4

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