Document B8naZYaYb2Kjpko3vEJgLBma8

918 CHAPTER 36 1958 Guide Table 3. Properties op Trichloromonofluoromethane (CCUF) Sat. Temp. F Abs. Press. Lb peb Sq In. Volume Enthalpy and Entropy Taken Fbom --40 F Enthalpy Entropy 25 F Superheat 50 F Superheat Liquid Vapor Liquid Vapor Liquid Vapor En thalpy En tropy En thalpy En tropy 0 2:59 0.01020 13.700 7.81 90.4 0.0178 0.1975 93.9 0.2049 97.4 0.2120 5 2.96 0.01024 12.100 8.81 91.2 0.0200 0.1974 94.7 0.2047 97.2 0.2117 10 3.38 0.01028 10.700 9.82 92.0 0.0222 0.1973 95.5 0.2045 99.0 0.2114 15 3.85 0.01032 9.530 10.80 92.8 0.0243 0.1971 96.3 0.2043 99.8 0.2111 20 4.36 0.01036 8.490 11.90 93.7 0.0264 0.1970 97.2 0.2041 100.7 0.2109 25 4.94 0.01040 7.580 12.90 94.5 0.0286 0.1969 98.0 0.2039 101.5 0.2107 30 5.57 0.01045 6.770 13.90 95.3 0.0307 0.1969 98.8 0.2038 102.3 0.2105 35 6.27 0.01049 6.080 14.90 98.1 0.032S 0.1968 99.6 0.2037 103.1 0.2103 40 7.03 0.01053 5.460 16.00 96.8 0.0349 0.1968 100.3 0.2036 103.8 0.2101 45 7.88 0.01057 4.920 17.00 97.6 0.0370 0.1967 101.1 0.2035 104.6 0.2099 50 8.79 0.01062 4.440 18.10 98.4 0.0391 0.1967 101.9 0.2034 105.4 0.2098 55 9.80 0.01066 4.020 19.10 99.2 0.0412 0.1967 102.7 0.2033 106.2- 0.2097 60 10.90 0.01071 3.640 20.20 100.0 0.0432 0.1967 103.5 -0.2033 107.0 0.2096 65 12.10 0.01076 3.300 21.30 100.8 0.0453 0.1967 104.3 0.2032 107.8 0.2094 70 13.40 0.01081 3.000 22.40 101.5 0.0473 0.1967 105.0 0.2032 108.5 0.2093 75 14.80 0.01086 2.740 23.50 102.2 0.0493 0.1967 105.7.- 0.2031 109.2 0.2092 80 16.30 0.01091 2.500 24.50 102.9 0.0513 0.1966 106.4 0.2030 109.9 0.2090 85 17.90 0.01096 2.280 25.60 103.6 0.0533 0.1966 107.1 0.2029 110.6 0.2089 90 19.70 0.01101 2.090 26.70 104.4 0.0553 0.1968 107.9 0.2028 111.4 0.2088 95 21.60 0.01106 1.918 27.80 105.1 0.0573 0.1966 108.6 0.2028 112.1 0.2087 100 23.60 0.01111 1.761 28.90 105.7 0.0593 0.1965 109.2 0.2027 112.7 0.2085 105 25.90 0.01116 1.620 30.10 106.4 0.0613 0.1965 109.9 0.2026 113.4 0.2084 * ASRE designation--Refrigerant 11. Table 4. Properties op Trichlorotrifluoroethane (C*C1>Fj)" Temp Pressure Volume Density Enthalpy prom --40F Entropy prom --40F Liquid Vapor Liquid Vapor Liquid Latent Vapor Liquid Vapor cu ft/lb cu ft/lb lb/cu ft lb/cu ft Btu/lb Btu/lb Btu/lb F deg F deg 0 0.8377 28.21* 0.00966 31.31 103.56 0.03194 7.98 70.92 78.89 0.0182 0.1725 4 8 .9503 27.99* 1.075 27.73* .00968 27.84 .00971 24.81 103.27 102.98 .03592 .04031 8.78 70.68 79.46 9.59 70.44 80.03 .0199 .0216 .1723 12 1.213 27.45* .00974 22.17 102.69 .04511 10.41 70.20 80.61 .0234 16 1.366 27.14* .00977 19.84 102.40 .05040 11.22 69.96 81.18 .0251 20 1.534 26.80* 0.00979 17.81 102.10 0.05616 12.03 69.72 81.75 0.0268 0.1722 24 1.719 26.42* .00982 16.02 101.81 .06243 12.85 69.48 82.33 .0285 28 1.922 26.01* .00985 14.43 101.51 .06929 13.67 69.24 82.91 .0302 32 2.145 25.55* .00988 13.03 101.21 .07675 14.49 69.00 83.49 .0318 36 2.388 25.06* .00991 11.79 100.91 .08483 15.32 68.75 84.07 .0335 40 2.655 24.52* 0.00994 10.68 100.60 0.09361 16.16 68.50 84.65 0.0352 0.1723 44 48 2.944 3.258 23.93* 23.29* .00997 .01000 9.703 100.30 8.830 99.99 .1031 .1133 16.99 68.25 85.24 17.82 68.00 85.82 .0368 .0385 . 1/24 52 3.602 22.59* .01003 8.044 99.68 .1243 18.66 67.74 86.40 .0401 56 3.973 21.83* .01006 7.342 99.37 .1362 19.50 67.48 86.98 .0418 60 4.374 21.02* 0.01010 6.713 99.05 0.1490 20.35 67.22 87.57 0.0434 0.1728 64 68 4.807 5.275 20.14* 19.18* .01013 .01016 6.149 5.640 98.73 98.42 .1626 .1773 21.19 66.96 88.15 22.05 66.69 88.74 .0450 .0467 .i/31 72 5.780 18.16* .01019 5.180 98.10 .1931 22.90 66.43 89.33 .0483 76 6.320 17.06* .01023 4.769 97.77 .2097 23.76 66.16 89.92 .0499 80 6.902 15.87* 0.01026 4.392 97.45 0.2277 24.63 65.88 90.51 0.0515 0.1736 84 7.527 14.60* .01030 4.051 97.12 .2468 25.49 65.60 91.09 .0531 88 8.194 13.24* .01033 3.742 96.79 .2672 26.36 65.32 91.68 .0547 92 8.908 11.79* .01037 3.463 96.46 .2888 27.24 65.04 92.28 .0563 96 9.668 10.24* .01040 3.208 96.13 .3117 28.11 64.75 92.86 .0578 100 10.48 1C4 11.35 108 12.28 110 12.76 8.59* 6.82* 4.93* 3.95* 0.01044 .01048 .01051 0.01053 2.976 2.762 2.567 2.477 95.79 95.46 95.12 94.95 0.3360 .3620 .3896 0.4038 28.99 29.89 ! 30.78 | 31.22 64.46 64.16 63.86 63.71 93.45 94.05 94.64 94.93 0.0594 .0610 .0626 0.0634 0.1716 * Inches of mercury below one atmosphere, t Standard cycle temperatures. * ASRE designation--Refrigerant 113. Refrigeration 919 Values of v, and vd for use in Equation 4 can be obtained directly or by calculation from the tables of properties of refrigerants. By a reversal of this same procedure the tabular data can'be used to determine the state of a mixture leaving an expansion valve. Consider a valve to which saturated liquid at pressure p, is admitted, and a mixture of saturated liquid and vapor at pressure pa is discharged. The quality of the material at discharge is then determined by making use of the fact that the expansion process is completely irreversible, is a throttling-process, and hence, occurs without change in enthalpy. Thus, the enthalpy of the mix ture, hm, is equal to the enthalpy of the saturated liquid at the entrance state, hi,,, and can therefore be read from the table. ' Thus, Af. = An, = Ayd (1 I-) (Art ; Afd) (5) or, where x = (Am -- Afd) -s- (Art -- Afd) (6) ht, = enthalpy of saturated liquid at entrance to expansion valve. Am = enthalpy of mixture. A,d = enthalpy of saturated vapor at discharge. Afd = enthalpy of liquid at discharge. x = proportion of liquid in the mixture, decimal. Vapor Compression Refrigeration Cycle Simple Cycle. The refrigerant cycle is the series of state changes (which occur in the conditioning processes) needed to restore the refrigerant to a condition in which it will possess the ability to extract heat from the space to be cooled. For all compression-type systems the cycle consists of four processes: heat gain in the evaporator; pressure rise in the compressor; heat loss in the condenser; pressure loss in the expansion valve. The com pression process is accomplished at the expense of energy added to the compressor in the form of shaft work, and the expansion process could be carried out, if the economics of the system would permit, in an expanding engine with consequent release of energy as shaft work. In ordinary sys tems, however, the additional first cost and maintenance costs of an expandmg engine so greatly exceed the advantage resulting from the work realized, that such engines are not used, and the pressure reduction is allowed to occur irreversibly in an expansion valve. Basically, then, a refrigeration cycle consists of two heat transfer processes and.two pressure change proc esses, no work entering into the heat transfer processes and--in the simple cycle--no heat transfer occurring during the pressure-change processes. The most common and least complicated type of refrigeration cycle is caUed the simple saturation cycle, and is shown diagrammatically in Fig. 3 and plotted upon pressure-enthalpy coordinates in Fig. 4. For this system, saturated vapor flows without gain or loss of heat from the evaporator to the suction of the compressor. During passage through the compressor the energy added as shaft work goes entirely to increase the enthalpy of he refrigerant, and the compression process, which is assumed to occur rreversibly and without external heat transfer, is characterized by constant ntropy. Thus, the state of the superheated vapor leaving the compressor .e determined from the tables of thermodynamic properties by noting e discharge pressure and fixing, also, the entropy of the saturated vapor entrance to the compressor. Superheated vapor from the compressor flows to the condenser where