Document dYvw71pD3nyy24EKeq7poVzze

American Society of Heating and Ventilating Engineers Guide, 1937! Table 1. Properties of Ammonia Sat. Temp. F Abs Press. Lb FEB Sq In. Volume liquid Vapor Heat Content and Entbopt Takbn From -40 F Heat Content liquid Vapor Entropy Liquid Vapor 100 F Superheat 200 F Superheat Ht. Ct. Entropy Ht. CL Entropy 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 30.42 0.02419 9.116 34.27 0.02432 8.150 38.51 0.02446 7.304 43.14 0.02460 6.562 48.21 0.02474 5.910 53.73 0.02488 5.334 59.74 0.02503 4.825 66.26 0.02518 4.373 73.32 0.02533 3.971 80.96 0.02548 3.614 89.19 0.02564 3.294 98.06 0.02581 3.008 107.60 0.02597 2.751 117.80 0.02614 2.520 128.80 0.02632 2.312 140.50 0.02650 2.125 153.00 0.02668 1.955 166.40 0.02687 1.801 180.60 0.02707 1.661 195.80 0.02727 1.534 211.90 0.02747 1.419 228.90 0.02769 1.313 42.9 48.3 53.8 59.2 64.7 70.2 75.7 81.2 86.8 92.3 97.9 103.5 109.2 114.8 120.5 126.2 132.0 137.8 143.5 149.4 155.2 161.1 611.8 0.0975 1.3352 613.3 0.1092 1.3253 614!9 0.1208 1.3157 616.3 0.1323 1.3062 617.8 0.1437 1.2969 619.1 0.1551 1.2879 620.5 0.1663 1.2790 621.7 0.1775 1.2704 623.0 0.1885 1.2618 624.1 0.1996 1.2535 625.2 0.2105 1.2453 626.3 0.2214 1.2373 627.3 0.2322 1.2294 628.2 0.2430 1.2216 629.1 0.2537 1.2140 629.9 0.2643 1.2065 630.7 0.2749 1.1991 631.4 0.2854 1.1918 632.0 0.2958 1.1846 632.6 0.3062 1.1775 633.0 0.3166 1.1705 633.4 0.3269 1.1635 666.8 1.4439 668.9 1.4339 670.9 1.4242 673.0 1.4148 675.0 1.4056 677.0 1.3965 678.9 1.3879 680.8 1.3794 682.7 1.3712 684.6 1.3630 686.4 1.3552 688.1 1.3474 689.9 1.3399 691.7 1.3326 693.3 1.3254 695.0 1.3184 696.6 1.3116 698.2 1.3048 699.7 1.2983 701.2 1.2919 702.7 1.2855 704.2 1.2793 720.3 1.5317 722.7 1.5215 725.0 1.5115 727.3 1.5018 729.6 1.4925 731.9 1.4833 734.2 1.4744 736.5 1.4658 738.6 1.4575 740.9 1.4493 743.1 1.4412 745.3 1.4335 747.4 1.4260 749.5 1.4186. 751.6 1.4114 753.7 1.4044 755.8 1.3976 757.9 1.3909 759.9 1.3843 761.9 1.3783 763.8 1.3718 765.7 1.3655 cp n = = 1.3172 Lv Table 2. Properties of Carbon Dioxide I Sat. Temp. F Ab8 Press. Lb per So In. Volume liquid Vapor Heat Content and Entbopt Taken From -40 F Heat Content liquid Vapor Entropy ' 50 F Superheat 100 -F Superheat liquid Vapor HtCt. Entropy Ht Ct Entropy 0 305.5 0.01570 0.29040 18.8 5 332.0 0.01592 0.26610 20.3 10 360.2 0.01614 0.24370 24.0 15 390.0 0.01637 0.22360 26.7 20 421.8 0.01663 0.20490 29.4 25 455.3 0.01690 0.18790 32.3 30 490.8 0.01719 0.17220 35.4 35 .529.3 0.01752 0.15770 38.5 40 567.8 0.01787 0.14440 41.7. .45 609.6 0.01826 0.13210 45.0 50 653.6 0.01868 0.12050 48.4 55 700.0 0:01917 0.10960 51.9 60 748.6 0:01970 0.09940 55.5 65 799.8 0.02034 0.08990 59.4 70 853.4 0.02112 0.08040 63.7 75 909.7 0.02217 0.07072 68.4 80 968.7 0.02370 0.06064 73.9 85 1030.3 0.02620 0.05006 81.4 87.8 1069.9 0.03454 0.03454 97.0 138.9 0.0418 0.3024 153.7 0.3342 167.5 0.3612 138.8 0.0472 0.3000 153.7 0.3312 167.8 0.3582, 138.7 0.0526 0.2970 138.5 0.0581 0.2939 138.3 0.0638 0.2909 138.1 0.0697 0.2879 137.8 0.0758 0.2849 137.3 0.0817 0.2813 136.7 0.0874 0.2776 135.9 0.0935 0.2739 135.0 0.1000 0.2699 133.7 0.1062 0.2656 132.1 0.1135 0.2608 130.2 0.1206 0.2554 127.5 0.1282 0.2487 123.7 0.1370 0.2404 118.7 0.1476 0.2304 112.2 0.1668 0.2169 153.7 0.3281 153.7 0.3257 153.7 0.3227 153.7 0.3196 153.7 0.3164 153.7 0.3147 153.7 0.3132 153.7 0.3112 153.7 0.3081 153.7 0.3051 153.7 0.3022 153.7 0.2995 153.7 0.2971 153.7 0.2947 153.7 0.2927 153.7 0.2909 168.0 0.3550 . 168.3 0.3517' 168.6 0.3489 168.8 0.3464 169.1 0.3441, 169.3 0.3415' 169.6 0.3391 169.9 0.3365 , 170.1 0.3342 170.4 0.3320 170.7 0.3297. 170.9 0.3277. 171.2 0.3257 171.4 0.3237 ' 171.7 0.3220 180.0 0.3204 97.0 0.1880 0.1880 153.7 0.2901 180.1 0.3199 y:-- = 1.28 t-V 36 ,. ^ Chapter 2--Refrigeration flows to the evaporator through an expansion valve which reduces its pressure and regulates its flow. The evaporator absorbs heat from a medium which is to be cooled. When this medium is water or brine, the evaporator is known as a water or brine cooler and the refrigeration system, if used for air cooling, is known as an indirect system. When the medium cooled is air, the evaporator is known as a direct expansion cooler and the system is known as a direct expansion system. Fundamentally, the function of-the system is to absorb heat at one temperature and pump it to a higher temperature, where it may be re moved by an available cooling medium: In order to conserve refrigerant. Heat of Compression Added to Gas virtually all refrigeration systems are completely closed and the same refrigerant is recirculated. Theoretical Mechanical Refrigeration Cycle The complete mechanical refrigeration cycle may be illustrated on the temperature-entropy diagram, and also.on the pressure-volume diagram both of which are shown in Fig. 2. Considering the theoretical cycle, saturated vapor is drawn into the compressor at a and compressed at constant entropy (adiabatically) and then delivered to the condenser at b. Condensation occurs at constant temperature Tt from b to c with a contraction from the vapor to the liquid volume. The line cd represents cooling from the temperature of the condenser to that of the evaporator by an external cooling 'means. At the same time, the pressure is lowered to Pi. Evaporation then occurs from d to a at temperature 7\, completing the work cycle abcda\ Since no ' external means of cooling the refrigerant liquid is normally available,-the cooling is generally accomplished by evaporation of a portion of the refrigerant. Since the work of'expansion is usually used up as friction in the expansion valve, this process is carried on at constant total heat, as represented by the line ce on the temperature-entropy diagram. Thus the refrigerating effect is represented by an area eagfe. While the normal 37 /