Document o9J7ZDx3zQQ95gGy3Oo3pmpNX

American Society of Heating and Ventilating Engineers Guide, 1936 Table 5. Properties of Methyl Chloride Sat. Tump. F Ass Press. Lb pkb Sq In. Volume Liquid Vapor Heat Content and Entbopt Taken From -40 F Heat Content Entropy 100 F Superheat 200 F Superheat Liquid Vapor Liquid Vapor Ht Ct Entropy Ht. Ct. Entropy 0 18.5 0.01628 s 20.89 0.01635 10 23.3 0.01645 IS 25.8 0.01652 20 28.3 0.01660 25 32.0 0.01669 , 30 35.0 0.01678 35 38.8 0.01689 40 42.8 0.01700 45 46.5 0.01710 50 51.0 0.01721 55 55.7 0.01727 60 61.0 0.01734 65 66.8 0.01746 70 72.6 0.01758 75 79.5 0.01768 80 87.0 0.01779 85 93.9 0.01790 90 102.0 0.01801 95 108.7 0.01813 too 117.0 0.01825 105 124.3 0.01836 110 133.0 0.01847 115 143.0 __________ __ 120 154.0 -- 5.00 4.52 4.09 3.73 3.37 3.07 2 78 2.55 2.32 2.13 1.94 1.79 1.64 1.51 1.39 1.28 1.18 1.09 1.01 0.94 0.87 ___ -- 14.5 16.3 18.0 19.9 21.7 23.5 25.2 27.0 28.9 30.7 32.5 34.5 36.5 38.5 40.5 42.5 44.5 46.3 48.0 50.0 52.0 53.8 55.5 57.3 59.0 194.0 0.032 0.424 215.6 0.467 237.2 195.3 0.036 0.4225 217.0 0.464 238.5 196.5 0.040 0.421 218.5 0.463 240.0 198.0 0.044 0.420 219.8 0.461 241.0 199.0 0.048 0.418 221.0 0.460 242.5 200.0 0.052 0.417 222.1 0.459 244.0 201.2 0.056 0.415 223.4 0.457 245.2 202.4 0.060 0.414 224.5 0.454 246.5 203.7 0.064 0.413 225.7 0.453 247.7 204.5 0.068 0.412 226.8 0.451 249.1 205.3 0.071 0.410 227.9 0.449 250.5 206.1 0.075 0.408- 228.8 0.448 251.7 207.0 0.079 0.406 229.6 0.446 253.0 207.5 0.083 0.404 230.5 0.443 254.3 208.0 0.086 0.402 231.3 0.441 255.5 208.5 0.090 0.400 232.2 0.439 256.8 209.0 0.093 0.398' 233.0 0.437 257.9 209.5 0.097 0.396 233.8 0.435 259.2 210.0 0.100 0.394 234.5 0.433 260.4 210.3 0.104 0.392 235.2 0.432 261.5 210.5 0.107 0.390 236.0 0.431 262.4 210.6 0.111 0.388 237.0 0.430 263.3 210.7 0.114 0.386 237.9 0.428 264.3 210.8 0.118 0.384 238.5 0.427 265.0 211.0 0.121 0.382 239.0 0.425 265.6 0.507 0.503 0.500 0.498 0.496 0.494 0.493 0.492 0.490 0.488 0.487 0.486 0.484 0.483 0.481 0.479 0.478 0.477 0.476 0.475 0.474 0.473 0.472 0.470 0.468 ' It-is frequently helpful to think of the compression of the vapor in terms of head. The head may be likened to a vertical column of vapor in which is located the vapor to be compressed. The compression occurs when the vapor is moved down from a level corresponding to Pi to.a new level corresponding .to Pa, in equilibrium with the surrounding-vapor. If this process is carried on isen tropically, the result will be the same as indicated previously. Then' if h is the head in-feet, W~h (3) This relationship may easily be seen from the fact that a small difference of head dh divided by the specific volume of the vapor V is equal to the increment of pressure difference dP. . Thus, dh. = VdP; also it can be seen by a comparison of the diagram that VdP = SdT, whence by integration all three of the previous ex pressions may be derived. Head is very useful in considering the performance of centrifugal com pressors, which merely substitute a centrifugal for the gravity head. .It is also useful in considering problems of fluid flow. In these problems, the head per degree can be obtained either by direct calculation or 42 EBBSESB-a Chapter 2--Refrigeration Table 6. Properties of Monofluorotrichloromethane (F) Sat. Temp. F Abs Press. Sq In- Volume Liquid Vapor Heat Content and Entbopt Taken From -40 F Heat Content Liquid Vapor Entropy Liquid Vapor 25 F Superheat 50 F Superheat Ht. Ct. Entropy Ht. Ct. Entropy 2 5Q 0.01020 13.7 7.81 90.4 0.0178 0.1975 93.9 0.2049 97.4 0.2120 0 2 Qft 0.01024 12.1 0.01028 10.7 8.81 91.2 0.0200 0.1974 94.7 0.2047 98.2 0.2117 9.82 92.0 0.0222 0.1973 95.5 0.2045 99.0 0.2114 10 \ as 0.01032 9.53 4 36 0.01036 8.49 10.8 11.9 92.8 0.0243 0.1971 96.3 0.2043 99.8 0.2111 93.7 0.0264 0.1970 97.2 0.2041 100.7 0.2109 zo 4 04 0.01040 7.58 12.9 : 94.5 0.0286 0.1969 98.0 0.2039 101.5 0.2107 s S7 0.01045 6.77 13.9 95.3 0.0307 0.1969 98.8 0.2038 102.3 0.2105 00 45 6.27 0.01049 7 03 0.01053 7.88 0.01057 8.79 0.01062 6.08 5.46 4.92 4.44 14.9 16.0 17.0 18:1 96.1 0.0328 0.1968 99.6 0.2037 103.1 0.2103 96.8 0.0349 0.1968 100.3 0.2036 103.8 0.2101 97.6 0.0370 0.1967 101.1 0.2035 104.6 0.2099 98.4 0.0391 0.1967 101.9 0.2034 105.4 0.2098 55 9.80 0.01066 4.02 19.1 99.2 0.0412 0.1967 102.7 0.2033 106.2 0.2097 60 65 70 7* an 10.9 12.1 13.4 14.8 16.3 0.01071 0.01076 0.01081 0.01086 0.01091 3.64 3.30 3.00 2.74 2.50 20.2 100.0 0.0432 0.1967 103.5 0.2033 107.0 0.2096 21.3 100.8 0.0453 0.1967 104.3 0.2032 107.8 0.2094 22.4 101.5 0.0473 0.1967 105.0 0.2032 108.5 0.2093 23.5, 102.2 0.0493 0.1967 105.7 0.2031 109.2 0.2092 24.5 102.9. 0.0513 0.1966 106.4 0.2030 109.9 0.2090 85 90 95 jfif) 17.9 19.7 21.6 23.6 0.01096 0.01101 0.01106 0.01111 2.28 2.09 1.918 1.761 25.6 26.7 27.8 28.9 103.6 0.0533 0.1966 107.1 0.2029 110.6 0.2089 104.4 0.0553 0.1966 107.9 0.2028 111.4 0.2088 105.1 0.0573 0.1966 108.6 0.2028 112.1 0.2087 105.7 0.0593 0.1965 109.2 0.2027 112.7 0.2085 105 25.9 0.01116 1.620 30.1 106.4 0.0613 0.1965 109.9 0.2026 113.4 0.2084 n= - = 113 approximately by dividing the total head by the temperature difference T2 -- Ti. The velocity head loss can then be calculated in degrees, using the customary formula V* = 2gh. Refrigerating Effect per Pound The refrigerating effect per pound, is computed by the same method, regardless of the type of refrigeration system. The solution is indicated on the temperature-entropy diagram of Fig. 2. Assuming that the vapor leaving the evaporator is saturated, the refrigerating effect.in Btu per pound is obtained by subtracting from the heat content of the vapor at temperature T\, the heat content of the liquid at Tt, or if the liquid is sub-cooled, the liquid temperature. Thus, the refrigerating effect in Btu per pound, is equal to . . H& - Hc = Ha - -He (4) If the vapor entering the compressor is superheated or supersaturated, a correction in the heat of the vapor is made accordingly. The. unit of refrigeration is the Ion, based on the latent heat of fusion of one ton of ice in 24 hours. ^' Thus one ton = 200 Btu per minute = 12,000 Btu per hour. .43