Document NNeaga6LNo4gaB91vrYyxQXyy

562 CHAPTER 38 1960 Guide Sat. Temp. F Aits. Frets. la p*r 0 23.87 2 24.89 4 25.96 5 26.51 6 27.05 Toble 1..... Properties of Dichlorodifiuoromethane (COjFJ* Yehfme Liquid Vapor Enthalpy liquid Vapor Enthalpy and Entropy Token From ---40 f Entropy 25 F Superheat Liquid Vapor Enthalpy Entropy 0.0110 0.0110 0.0111 0.0111 0.0111 1.637 1.574 1.514 1.485 1.457 8.25 8.67 9.10 9.32 9.53 78.21 78.44 78.67 78.79 78.90 0.01869 0.01961 0.02052 0.02097 0.02143 0.17091 0.17075 0.17060 0.17052 0.17045 81.71 81.94 82.17 82.29 82.41 0.17829 0.17812 0.17795 0.17786 0.17778 SO F Superheat Enthalpy Entropy 85.26 85.51 85.76 85.89 86.01 0.18547 0.18529 0.18511 0.18502 0.18494 8 28.18 0.0111 1.403 9.96 79.13 0.02235 0.17030 82.66 0.17763 86.26 0.18477 10 29.35 0.0112 1.351 10.39 79.36 0.02328 0.17015 82.90 0.17747 86.51 0.18460 12 30.56 0.0112 1.301 10.82 79.59 0.02419 0.17001 83.14 0.17733 86.76 0.18444 14 31.80 0.0112 1.253 11.26 79.82 0.02510 0.16987 83.38 0.17720 87.01 0.18429 16 33.08 0.0112 1.207 11.70 80.05 0.02601 0.16974 83.61 0.17706 87.26 0.18413 18 34.40 0.0113 1.163 12.12 80.2? 0.02692 0.16961 83.85 0.17693 87.51 0.18397 20 35.75 0.0113 1.121 12.55 80.49 0.02783 0.16949 84.09 0.17679 87.76 0.18382 22 37.15 0.0113 1.081 13.00 80.72 0.02873 0.16938 84.32 0.17666 88.00 0.18369 24 38.58 0.0113 1.043 13.44 80.95 0.02963 0.16926 '84.55 0.17652 88.24 0.18355 26 40.07 0.0114 1.007 . 13.88 81.17 0.03053 0.16913 84.79 0.17639 88.49 0.18342 28 41.59 0.0114 0.973 14.32 81.39 0.03143 0.16900 85.02 0.17625 88.73 0.18328 80 43.16 0.0115 0.939 14.76 81.61 0.03233 0.16887 85.25 0.17612 88.97 0.1S315 32 44.77 0.0115 0.908 15.21 81.83 0.03323 0.16876 85.48 0.17600 89.21 0.18303 34 46.42 0-0115 0.877 15.65 82.05 0.03413 0.16865 85.71 0.17589 89.45 0.18291 36 48.13 0.0116 0.848 16.10 82.27 0.03502 0.16854 85.95 0.17577 89.68 0:18280 38 49.88 0.0116 0.819 16.55 82.49 0.03591 0.16843 86.18 0.17566 89.92 0.18268 39 50.78 0-0116 0.806 16.77 82.60 0.03635 0.16838 86.29 0.17560 90.04 0.18262 40 51.68 0.0116 0.792 17.00 82.71 0.03680 0.16833 86.41 0.17554 90.16 0-18256 41 52.70 0.0116 0.779 17.23 82.82 0.03725 0.16828 86.52 0.17549 90.28 0.18251 42 53.51 0.0116 0.767 17,46 82.93 0.03770 0.16823 86.64 0.17544 90.40 0.18245 44 55.40 0.0117 0.742 17.91 83.15 0.03859 0.16813 86.86 0.17534 90.65 0.18235 46 57.35 0.0117 0.718 18.36 83.36 0.0394S 0.16803 87.09 0.17525 90.89 0.18224 48 59.35 0.0117 0.695 18.82 83.57 0.04037 0.16794 87.31 0.17515 91.14 0.18214 50 61.39 0.0118 0.673 19.27 83.78 0.04126 0.16785 87.54 0.17505 91.38 0.18203 52 63.49 0.0118 0.652 19.72 83.99 0.04215 0.16776 87.76 0.17496 91.61 0.18193 54 65.63 0.0118 0.632 20.18 84.20 0.04304 0.16767 87.98 0.17486 91.83 0.18184 56 67.84 0.0119 0.612 20.64 84.41 0.04392 0-16758 88.20 0.17477 92.06 0.18174 58 70.10 0.0119 0.593 21.11 84.62 0.04480 0.16749 88.42 0.17467 92.28 0.18165 60 72.41 0.0119 0.575 21.57 84.82 0.04568 0.16741 88.64 0.17458 92.51 0.18155 62 74.77 0.0120 0.557 22.03 85.02 0.01657 0.16733 88.86 0.17450 92.74 0.18147 64 77.20 0.0120 0.540 22.49 85.22 0.04745 0.16725 89.07 0.17442 92.97 0.18139 66 79.67 0.0120 0.524 22.95 85.42 0.04833 0.16717 89.29 0.17433 93.20 0.18130 68 82.24 0.0121 0.508 23.42 85.62 0.04921 0.16709 89.50 0.17425 93.43 0.18122 70 84.82 0.0121 0.493 23.90 85.82 0.05009 0.16701 89.72 0.174L7 93.66 0.18114 72 87.50 0.0121 0.479 24.37 86.02 0.05097 0.16693 89.93 0.17409 93.99 0.18106 74 90.20 0.0122 0.464 24.84 86.22 0.05185 0.16685 90.14 0.17402 94.12 0.18098 76 93.00 0.0122 0.451 20.32 86.42 0.05272 0.16677 90.36 0.17394 94.34 0.18091 78 95.85 0.0123 0.438 25.80 86.61 0.05359 0.16669 90.57 0.17387 94.57 0.18083 80 98.76 0.0123 0.425 26.28 86.80 0.05446 0.16662 90.78 0.17379 94.80 0.18075 82 101.70 0.0123 0.413 26.76 86.99 0.05534 0.16655 90.98 0.17372 95.01 0.18068 84 104.8 0.0124 0.401 27.24 87.18 0.05621 0.16648 91.18 0.17365 95.22 0.18061 68 107.9 0.0124 0.389 27.72 87.37 0.05708 0.16640 91.37 0.17368 95.44 0.18054 88 111.1 0.0124 0.378 28.21 87.56 0.05795 0.16632 91.57 0.17351 95.65 0.18047 90 114.3 0.0125 0.368 28.70 87.74 0.05882 0.16624 91.77 0.17344 95.86 0.18040 92 117.7 0.0125 0.357 29.19 87.92 0.05969 0.16616 91.97 0.17337 96.07 0.18033 Refrigeration 563 Sot. Temp. F Ab*. Piet*. lb per Sq fa 94 121.0 96 124.5 98 128.0 100 131.6 102 135.3 Table 1 .... Properties of Dichlorodifiuoromethane (CG,F*}" (Concluded) Vohete liquid Vapor Enthalpy liquid Vapor Enthalpy and Entropy Token From --40 F Entropy 25 F Superheat liquid Vapor Enthalpy Entropy 0.0126 0.0128 0.0126 0.0127 0.0127 0.347 0.338 0.328 0.319 0.310 29.68 30.18 30.67 31.16 31.65 88.10 88.28 88.45 88.62 88.79 0.06056 0.06143 0.06230 0.06316 0.06403 0.10608 0.16600 0.16592 0.16584 0.16576 92.16 92.36 92.55 92.75 92.93 0.17330 0.17322 0.17315 0.17308 0.17301 104 139.0 0.0128 0.302 32.15 88.95 0.06490 0.16568 93.11 0.17294 106 142.8 0.0128 0.293 32.65 89.11 0.06577 0.16560 93.30 0.17288 108 146.8 0.0129 0.285 33.15 89.27 0.06663 0.16551 93.48 0.17281 110 150.7 0.0129 .0.277 33.65 89.43 0.06749 0.16542 93.66 0.17274 112 154.8 0.0130 0.269 34.15 89.58 0.06836 0.16533 83.82 0.17266 114 158.9 0.0130 0.262 34.65 89.73 0.06922 0.16524 93.98 0.17258 116 163.1 0.0131 0.254 35.15 89.87 0.07008 0.16515 94.15 0.17249 118 167.4 0.0131 0.247 35.65 90.01 0.07094 0.16505 94.31 0.17241 120 171.8 0.0132 0.240 36.16 90.15 0.07180 0.16495 94.47 0.17233 122 176.2 0.0132 0.233 36.66 90.28 0.07266 0.16484 94.63 O.17224 124 180.8 0.0133 0.227 37.16 90.40 0.07352 0.18473 94.78 0.17215 126 185.4 0.0133 0.220 37.67 90.52 0.07437 0.16462 94.94 0.17206 128 190. i 0.0134 0.214 38.18 90.64 0.07522 0.16450 95.09 0.17196 130 194.9 0.0134 0.208 38.69 90.76 0.07007 0.16438 95.25 0.17186 132 199.8 0.0135 0.202 39.19 90.86 0-07691 0.16425 95.41 0.17176 134 204.8 0.0135 136 209.9 0.0136 138 215.0 0.0137 140 220.2 0.0138 * ASHRAE dcajpatarm RafruBPmat IS. 0.196 0.191 0.185 0.180 39.70 40.21 40.72 41.24 90.96 91.06 91.15 91.24 0.07775 0.07858 0.07941 0.08024 0.16411 0.16396 0.16380 0.16363 95.56 95.72 95.87 96.03 0.17166 0.17156 0.17145 0.17134 SO F Superheat Enthalpy Entropy 96.28 96.50 96.71 96.92 97.12 0.18028 0.18018 0.18011 0.18004 0.17998 97.32 97.53 97.73 97.93 98.11 0.17993 0.17987 0.17982 0.17976 0.17969 98.29 98.48 98.66 98.84 99.01 0.17961 0.17954 0.17946 0.17939 0.17931 99.18 .99.35 99.53 99.70 99.87 0.17922 0.17914 0.17906 0.17897 0.178S9 100.04 100.22 100.39 100.56 0.17881 0.17873 0.17864 0.17856 to restore the refrigerant to a condition in which it will pos sess 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 compression 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 expand ing engine with consequent release of energy as shaft work. In ordinary systems, however, the additional first cost and maintenance cost of an expanding engine so greatly exceed the advantage resulting from the work realised, that such engines are not used, and instead, the pressure reduction is allowed to occur irreversibly in an expansion valve. Basically, then, a refrigeration cycle consists of two heat-transfer proc esses and two pressure-change processes, no work entering into the heat-transfer processes and--in the simple cycle-- do heat transfer occurring during the pressure-change proc esses. The most common and least complicated type of refrigera tion cycle is called the simple saturation cycle, and is shown diagrammatically in Fig. 3 and plotted upon pressure-en thalpy coordinates in Fig. 4. For this system, saturated va por 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 the refrigerant, and the compression process, which is assumed to occur reversibly and without external heat transfer, is characterized by constant entropy. Thus, the state of the superheated vapor leaving the com pressor can be determined from the tables of thermody namic properties by noting the discharge pressure and fixing, also, the entropy of the saturated vapor at entrance to the compressor. Superheated vapor from the compressor flows to the con denser where de-superheating and condensation take place. From the condenser the refrigerant flows to the expansion valve, undergoes a constant-enthalpy pressure reduction, and returns to the evaporator where it again removes a quantity of undesired heat. WheD the evaporator is arranged to permit direct cooling of room air by the refrigerant, the system is said to be of the direct-expansion type, while a system in which the evaporating refrigerant cools water or brine, which in turn cools the air, is said to be indirect. Although many differences exist between most actual systems and that of the simple saturation cycle, this latter is, nonetheless, of great value in that it provides an extremely simple method of rap idly achieving an approximate analysis of probable power requirements, compressor size, etc. Further, the equations used in analysis of a simple saturation cycle form the basis of the more complex treatments required for compound re frigeration cycles. For these reasons a typical simple satura tion problem will be worked in detail. Example l: A. simple saturation cycle carries a 7-ton load when operating between suction and discharge pressure of s'