Document EdOxnqMD705mOJG3or11d2a4b

546 CHAPTER 38 1959 Guide Table 2 .... Properties of Monochlorodifluoromefhane (CHQF*)* Sot. Tmap. f AA*. Pntt, U> porSqln. Vobnm Enthalpy Enthgfry and Entropy fetea treat -- 40 F Entropy 50 Dog Saporhuat liquid Vapor Liquid Vapor liquid Vapor Enthalpy Entropy 100 Dag Soparheaf Enthalpy Entropy 0 38.79 0.01192 1.373 10.63 105.02 0.0240 0.2293 112.35 0.2446 120.00 0.2590 2 40.43 0.01195 1.320 11.17 105.24 0.0251 0.2289 112.59 0.2442 120.26 0.2586 4 42.14 0.01198 1.270 11.70 105.45 0.0262 0.2285 112.83 0.2438 120.52 0.2581 5 43.02 0.01200 1.246 11.97 105.56 0.0268 0.2283 112.95 0.2436 120.65 0.2579 6 43.91 0.01201 1.221 12.23 105.66 0.0274 0.2280 113.07 0.2434 120.78 0.2577 8 45.74 0.01205 1.175 - 12.76 105.87 0.0285 0.2276 113.31 0.2430 121.04 0.2572 10 12 14 16 18 20 22 24 26 . 28 30 32 84 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 47.63 49.58 51.59 53.66 55.79 57.98 60.23 .62.55 64.94 67.40 69.93 72.53 75.21 77.97 80.81 83.72 86.69 89.74 92.88 96.10 99.40 102.8 106.2 109.8 113.5 117.2 . 121.0 . 124.0 128.9 133.0 137.2 141.5 145.9 150.4 155.0 159.7 164.5 169.4 174.5 179.6 0.0120S 0.01211 0.01215 0.01218 0.01222 1.130 1.088 1.048 1.009 0.9721 13.29 13.82 14.36 14.90 15.44 106.08 106.29 106.50 106.71 106.92 0.0296 0.0307 0.0319 0.0330 0.0341 0.01225 0.01229 0.01232 0.01236 0.01239 0.9369 0.9032 0.8707 0.8398 0.8100 15.98 16.52 17.06 17.61 18.17 107.13 107.33 107.53 107.73 107.93 0.0352 0.0364 0.0375 0.0379 0.0398 0.01243 0.01247 0.01250 0.01254 0.01258 0.7816 0.7543 0.7283 0.7032 0.6791 18.74 19.32 19.90 20.49 21.09 108.13 108.33 108.52 108.71 108.90 0.0409 0.0421 0.0433 0.0445 0.0457 0.01262 0.01266 0.01270 0.01274 0.01278 0.6559 0.6339 0.6126 0.5922 0.5726 21.70 22.29 22.90 23.50 24.11 109.09 109.27 109.45 109.63 109.80 0.0469 0.0481 0.0493 0.0505 0.0516 0.01282 0.01286 0.01290 0.01294 0.01299 0.5537 0.5355 0.5184 0.5014 0.4849 24.73 25.34 25.95 26.58 27.22 109.98 110.14 110.30 110.47 110.63 0.0528 0.0540 0.0552 0.0564 0.0576 0.01303 0.01307 0.01312 0.01316 0.01320 0.4695 0.4546 0.4403 0.4264 0.4129 27.83 28.46 29.09 29.72 30.35 110.78 110.93 111.08 111.22 111.35 0.0588 0.0600 0.0612 -.0.0624 0.0636 0.01325 0.01330 0.01334 0.01339 0.01344 0.4000 0.3S75 0.3754 0.3638 0.3526 30.99 31.65 32.29 32.94 33.61 111.49 111.63 111.75 111.88 112.01 0.0648 0.0661 0.0673 0.0684 0.0696 0.01349 0.01353 0.01358 0.01363 0.01368 0.3417 0.3313 0.3212 0.3113 0.3019 34.27 34.92 35.60 36.28 36.94 112.13 112.24 112.36 112.47 112.57 0.0708 0.0720 0.0732 0.0744 0.0756 0.2272 0.2268 0.2264 0.2260 0.2257 113.55 113.79 114.02 114.25 114.48 0.2426 0.2422 0.2418 0.2414 0.2410 121.30 121.56 121.82 122.08 122.33 0.2568 0.2564 0.2560 0.2556 0.2552 0.2253 0.2249 0.2246 0.2242 0.2239 114.71 114.94 115.17 115.40 115.62 0.2406 0.2402 0.2398 0.2395 0.2391 122.59 122.84 123.10 123.35 123.60 0.2548 0.2544 0.2540 0-2537 0.2533 0.2235 0.2232 0.2228 0.2225 0.2222 115.84 116.07 116.29 116.52 116.74 0.2387 0.2383 0.2380 0.2376 0.2373 123.85 124.10 124.35 124.59 124.84 0.2529 0.2525 0.2522 0.2518 0 2515 0.2218 0.2215 0.2211 0.2208 0.2205 116.96 117.18 117.40 117.61 117.82 0.2369 0.2366 0.2363; 0.2359 0.2356 . 125.08 125.32 125.56 125.80 126;04 ' 0.2511 0.2508 0.2504 0.2501 0.2497 0.2201 0.2198 0.2194 0.2191 0.2188 118.02 118.22 118.42 118.62 118.82 0.2353 0.2350 0.2347 0.2343 0.2340 126.27 126.50 126.73 126.96 127.19 0.2494.. 0.2491 0.2488 0.2484 0.2481 0.2185 0.2181 0.2178 0.2175 0.2172 119.01 119.21 119.40 119.59 119.77 0.2337 0.2334 0.2331 0.2327 0.2324 127.42127.65 127.87 128.10 128.32 0.2478 0.2475 0.2472 0.2469 0.2466 0.2168 0.2165 0.2162 0.2158 0.2155 119.96 120.16 120.32 120.50 120.67 0.2321 0.2318 0.2315 0.2312 0.2309 128.54 128.76 128.97 129.19 129.40 0.2463 0.2460 0.2457 0.2455 0.2452 0.2151 0.2148 0.2144 0.2140 0.2137 120.85 121.02 121.18 121.34 121.50 0.2306 0.2303 0.2300 0.2297 0.2294 129.61 129.82 130.02 130.23 130.43 0.2449 0.2446 0.2443 0.2441 0.2438 Refrigeration 547 Table 2 .... Properties of Monochlorodifluoromethane (CHCIFJ* (Cone/odet/) Enthalpy and Entropy Tafean from --40 F Sat. Totup. F Ah*. Pmx. lb pwSqfa. Vbm Enthalpy Entropy 50 Deg Superheat liquid Vapor liquid Vapor Liquid Vapor Enthalpy .bitropy 100 Deg Superheat Enthalpy Ertrcpy 90 184.8 0.01374 0.2928 37.61 112.67 0.0768 0.2133 92 190.1 0.01379 0.2841 38.28 112.76 0.0780 0.2130 94 195.6 0.01384 0.2755 38.97 112.85 0.0792 0.2126 96 201.2 0.01390 0.2672 39.65 112.93 0.0603 0.2122 98 206.8 0.01396 0.2594 40.32 113.00 0.0815 0.2119 100 212.6 0.01402 0.2517 40.98 113.06 0.0827 0.2115 102 218.5 0.01408 0.2443 41.65 113.12 0.0839 0.2111 104 224.6 0.01414 0.2370 42.32 113-16 0.0851 0.2107 106 230.7 0.01420 0.2301 42.98 .113.20 0.0862 0.2104 108 237.0 0.01426 0.2233 43.66 113.24 0.0874 0.2100 110 243.4 0.01433 0.2167 44.35 113.29 0.0886 0.2096 112 249.9 0.01440 0.2104 45.04 113.34 0.0898 0.2093 114 256.6 0.01447 0.2043 45.74 113.38- 0.-0909^ 0.2089 116 263.4 0.01454 0.1983 46.44 113.42 0.0921 0.2085 118 270.3 0.01461 0.1926 47.14 113.46 0.0933 0.2081 120 277.3 0.01469 0.1871 47.86 113.52 0.0945 Date bens Euwtio Cbemkele, lafc, IMS. * ASRE designation--Refricetent *2. 0.2078 121.66 121.82 121.97 122.12 122.28 122.40 122.53 122.66 122.79 122.92 123.04 123.16 123.28 123.40 123.51 123.62 0.2291 0.2288 0.2285 0.2282 0.2279 0.2276 0.2273 0.2270 0.2267 0.2264 0.2261 0.2258 0.2255 0.2253 0.2250 0.2247 130.63 130.83 131.03 131.23 131.42 131.61 131.80 131.99 132.17 132.35 132.53 132.71 132.88 133.05 133.22 133.39 0.2435 0.2432 0.2429 0.2427 0.2424 0.2421 0.2418 0.2416 0.2413 0-2411 0.2408 0.2405 0.2403 0.2400 0.2398 0.2395 52.7 psia and 121 psia with dichlorodifluoromethane, CCI'*F* . as the refrigerant. Determine: (a) the cooling effect provided by each pound of refrigerant; (b) the refrigerant circulating rate; (c) the horsepower reauired; (d) the quantity of heat to ' be dissipated from the condenser; (c) the required condenser cooling water, in gallons per minute, if the temperature rise of water passing through the condenser ts 8 deg; (/) the bore - and stroke of a double acting cylinder (neglecting the effect of the piston rod) if speed of compressor is'500 revolutions per minute; (p) coefficient of performance. ") Solution: (o) Saturated liquid CC1*F* at 121 psia leaves the condenser and enters the expansion valve. The enthalpy of this material (from Table 1} is 29.68 Btu per pound, and this must . also be its enthalpy at entrance.to the evaporator. Leaving the evaporator as a,saturated vapor at 52.7 psia, its enthalpy is 82.82, so the refrigerating effect must be 82.82 -- 29.68 = 53.14 Btu per pound. - ^ (b) The ' refrigerant circulating rate is equal to the total heat to be picked up in unit time, divided by the' pickup per pound of refrigerant or, ' Wt -- (7 ton'X 200) + 53.14"= 28.3 lb per minute. (c) The horsepower required is eaual to the increase in energy, of the refrigerant passing through the compressor (expressed in Btu per minute) divided by the conversion factor 42.42, which is the number of Btu per minute corresponding to 1 hp, (bp) - BV(k - h,.) + 42.42 (7) where (hp) = horsepower. W, -- refrigerant circulating rate in pounds per minute. Atf = enthalpy of vapor at condition of discharge from - compressor.' h%, - enthalpy of saturated vapor entering compressor. ' 'Wt is known from (b) and A. is the enthalpy of refrigerant as it enters the compressor in a saturated vapor state at 52.7 psia; thus A= 82.82. In order to determine A* , the state of the refrigerant must first be determined at the compressor discharge. At the known suction state the entropy (from.Table 1 for saturated vapor at 52.7 psia) is 0.16828 and, since the compression is assumed to occur isentropically, it therefore follows that the discharge stage must have the entropy at 121 psia. From the table the entropy of vapor superheated 25 deg is 0.17330, so the super heat, , possessed by the actual gas discharged from this compressor can be obtained by interpolation as, W 0.16828 - 0.16608 25 " 0.17330 - 0.16608 from which t* = 7.6 deg. As the saturation temperature at 121 psia is 94 F the actual temperature, b , of the vapor leaving-the compressor is, U = 94 + tw = 94 + 7.6 = 101.6 F. By the same kind of interpola tion the enthalpy of the discharged vapor can be.determined from the enthalpies given for vapor superheated 25 F and for saturated vapor, (A, - 88.10) ' (0.16828 - 0.16608) (92.16 - 88.10) " (017330 - 0.16608) from which, Kt -- 89.34 Btu per pound. Then substituting in Equation 7, (hp) = 28.3 (89-34 - 82.82) -5- 42.42 = 4.03. (d) The rate of heat loss from the condenser, Q. , must be equal to the sum of the energies picked up by the refrig erant in the evaporator and the compressor, Qt =. 53.14 4(89.34 - 82.82) - 53.14 + 6.52 - 59.66 Btu per pound or 26-3 X 59.66 ** 1569 Btu per minute. This same figure can, o! course, be determined more directly by subtraction of the enthalpy z'