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A refrigerant 22 vapor compression system includes a liquid-to-suction heat exchanger in the system. The heat exchanger warms saturated vapor coming from the evaporator from -10 to 5 C with liquid which comes from the condenser at 30 C. The compressions are isentropic in both cases listed below. (a) Calculate the coefficient of performance of the system without the heat exchanger but with the condensing temperature at 30 C and an evaporating temperature of -10 C. (b) Calculate the coefficient of performance of the system with the heat exchanger?

A refrigerant 22 vapor compression system includes a liquid-to-suction heat exchanger in the system. The heat exchanger warms saturated vapor coming from the evaporator from -10 to 5 C with liquid which comes from the condenser at 30 C. The compressions are isentropic in both cases listed below. (a) Calculate the coefficient of performance of the system without the heat exchanger but with the condensing temperature at 30 C and an evaporating temperature of -10 C. (b) Calculate the coefficient of performance of the system with the heat exchanger?

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
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In this problem, I can't figure out where in the Table A-7 I can find the h_2 needed for both (a) and (b), please tell me how to find it, also how are they different with or without heat exchanger, when it comes to the same Table?

This is the Solution manual for the, Stoecker, W. F., Jones, J. W. (1982). Refrigeration and Air Conditioning, 2nd ed., McGraw-Hill, Inc.

10-7. A refrigerant 22 vapor compression system includes a liquid-to-suction heat exchanger in the system. The heat exchanger warms saturated vapor coming from the evaporator from -10 to 5 C with liquid which comes from the condenser at 30 C. The compressions are isentropic in both cases listed below. (a) Calculate the coefficient of performance of the system without the heat exchanger but with the condensing temperature at 30 C and an evaporating temperature of -10 C. Calculate the coefficient of performance of the system with the heat exchanger? (b) Solution: (a) Without heat exchanger At 1,6, -10 C, Table A-6. h₁ = 401.555 kJ/kg s₁ = 1.76713 kJ/kg.K At 2, 30 C, constant entropy, Table A-7 h₂ = 431.787 kJ/kg (b) At 3,4, 30 C, Table A-6. h₂ = 236.664 kJ/kg At 5, h =h₂ = 236.664 kJ/kg h₁-h5 h₂ h₁ coefficient of performance = 5.46 . . .Ans. coefficient of performance = With heat exchanger At 6, -10 C, Table A-6 h = 401.555 kJ/kg = 401.555-236.664 431.787-401.555 At 1,-10 C evaporator temperature, 5 C, Table A-7 h₁ = 411.845 kJ/kg At 3, 30 C, table A-6 h₂ = 236.664 kJ/kg. At 2, 30 C, constant entropy, Table A-7 h₂ = 444.407 kJ/kg Since no mention of subcooling. h=h₂=h₂ = 236.664 kJ/kg = 411.845-236.664 444.407-411.845 coefficient of performance = h₁-h5 h₂-h₁ coefficient of performance = 5.38... Ans. Table A-7 Refrigerant 22: properties of superheated vapor 1,"C v, L/kg v, L/kg h, kJ/kg s, kJ/kg - K Saturation temperature, -20°C 1.7841 1.7969 92.8432 397.467 400.737 95.1474 404.017 97.4256 99.6808 101.915 104.130 407.307 1.8095 1.8219 1.8341 1.8461 1.8580 1.8697 1.8813 1.8928 -20 -15 -10 -5 0 5 10 15 20 25 5 10 15 20 25 30 35 40 45 50 20 25 30 35 40 45 50 55 60 65 106.328 108.510 110.678 112.832 35 40 45 50 55 60 65 70 75 80 410.610 413.926 417.258 420.606 423.970 426.353 Saturation temperature, 5°C 40.3556 407.143 41.4580 42.5379 410.851 414.542 43.5979 44.6401 45.6665 425.562 418.222 421.894 Table A-7 (continued) 46.6786 429.229 47.6779 432.897 436.569 48.6656 49.6427 440.247 1.7446 1.7578 1.7708 1.7834 1.7958 1.8080 1.8200 1.8319 1.8435 1.8550 Saturation temperature, 20°C 26.0032 411.918 26.7900 415.977 27.5542 419.991 28.2989 423.970 29.0264 427.922 29.7389 431.852 30.4379 435.766 31.1250 439.668 31.8012 443.561 32.4678 447.450 Saturation temperature, 32°C 19.0907 417,648 19.7093 422.014 20.3062 426.310 20.8847 430.549 21.4471 434.743 438.900 21.9956 443.028 22.5318 23.0571 447.133 451.219 23.5726 24.0794 455.292 1.7246 1.7383 1.7517 1.7646 1.7774 1.7899 1.8021 1.8141 1.8258 1.8374 1.7182 1.7322 1.7458 1.7591 1.7719 1.7845 1.7968 1.8089 1.8207 1.8323 h, kJ/kg s, kJ/kg - K Saturation temperature, -10°C 401.555 65.3399 67.0081 404.983 68.6524 408.412 70.2751 411.845 415.283 71.8785 418.730 73.4644 75.0346 422.186 425.653 76.5904 1.7671 1.7800 1.7927 1.8052 1.8174 1.8295 1.8414 1.8531 Saturation temperature, 10°C 34.7136 408.835 35.6907 412.651 416.442 36.6454 420.215 37.5804 38.4981 423.974 39.4002 427.724 431.469 40.2884 41.1642 435.211 42.0286 438.954 Saturation temperature, 25°C 22.6242 413.289 23.3389 417.487 24.0306 421.627 24.7027 425.721 25.3575 429.779 25.9974 433.807 26.6239 437.813 27.2386 441.801 27.8427 445.777 1.7377 1.7511 1.7642 1.7769 1.7894 1.8017 1.8137 1.8256 1.8373 1.7183 1.7322 1.7458 1.7590 1.7718 1.7844 1.7967 1.8087 1.8206 Saturation temperature, 34°C 1.7099 1.7243 1.7382 1.7517 1.7647 1.7775 1.7899 1.8021 1.8141 1.8258 17.8590 416.325 18.4675 420.792 19.0526 425.174 429.487 19.6178 20.1660 433.747 20.6994 437.963 21.2199 442.143 21.7289 446.294 22.2278 450.424 454.535 22.7176 v, L/kg h, kJ/kg s, kJ/kg K Saturation temperature, 0°C 1.7518 1.7649 1.7777 1.7903 1.8026 1.8148 Saturation temperature, 15°C 405.361 47.1354 48.3899 408.969 416.159 49.6215 412.567 50.8328 52.0259 53.2028 29.9874 30.8606 419.649 423.339 410.430 414.362 31.7114 418.260 32.5427 422.133 33.3568 425.985 34.1556 429.823 34.9409 433.650 35.7139 437.470 Saturation temperature, 30°C 19.7417 414.530 20.3962 418.881 21.0272 423.159 21.6381 427.378 22.2316 431.549 22.8101 435.683 23.3733 439.787 23.9288 443.867 1.7120 1.7262 1.7400 1.7534 1.7664 1.7791 1.7915 1.8036 Saturation temperature, 36°C 17.2953 419.483 17.8708 423.961 18.4247 428.358 18.9603 432.690 19.4802 436.970 19.9865 441.207 20.4807 445.410 20.9643 449.586 21.4385 453.739 1.7162 1.7304 1.7442 1.7575 1.7704 1.7830 1.7954 1.8074 1.8193 1.7311 1.7556 1.7578 1.7707 1.7833 1.7956 1.8078 1.8197
Transcribed Image Text:10-7. A refrigerant 22 vapor compression system includes a liquid-to-suction heat exchanger in the system. The heat exchanger warms saturated vapor coming from the evaporator from -10 to 5 C with liquid which comes from the condenser at 30 C. The compressions are isentropic in both cases listed below. (a) Calculate the coefficient of performance of the system without the heat exchanger but with the condensing temperature at 30 C and an evaporating temperature of -10 C. Calculate the coefficient of performance of the system with the heat exchanger? (b) Solution: (a) Without heat exchanger At 1,6, -10 C, Table A-6. h₁ = 401.555 kJ/kg s₁ = 1.76713 kJ/kg.K At 2, 30 C, constant entropy, Table A-7 h₂ = 431.787 kJ/kg (b) At 3,4, 30 C, Table A-6. h₂ = 236.664 kJ/kg At 5, h =h₂ = 236.664 kJ/kg h₁-h5 h₂ h₁ coefficient of performance = 5.46 . . .Ans. coefficient of performance = With heat exchanger At 6, -10 C, Table A-6 h = 401.555 kJ/kg = 401.555-236.664 431.787-401.555 At 1,-10 C evaporator temperature, 5 C, Table A-7 h₁ = 411.845 kJ/kg At 3, 30 C, table A-6 h₂ = 236.664 kJ/kg. At 2, 30 C, constant entropy, Table A-7 h₂ = 444.407 kJ/kg Since no mention of subcooling. h=h₂=h₂ = 236.664 kJ/kg = 411.845-236.664 444.407-411.845 coefficient of performance = h₁-h5 h₂-h₁ coefficient of performance = 5.38... Ans. Table A-7 Refrigerant 22: properties of superheated vapor 1,"C v, L/kg v, L/kg h, kJ/kg s, kJ/kg - K Saturation temperature, -20°C 1.7841 1.7969 92.8432 397.467 400.737 95.1474 404.017 97.4256 99.6808 101.915 104.130 407.307 1.8095 1.8219 1.8341 1.8461 1.8580 1.8697 1.8813 1.8928 -20 -15 -10 -5 0 5 10 15 20 25 5 10 15 20 25 30 35 40 45 50 20 25 30 35 40 45 50 55 60 65 106.328 108.510 110.678 112.832 35 40 45 50 55 60 65 70 75 80 410.610 413.926 417.258 420.606 423.970 426.353 Saturation temperature, 5°C 40.3556 407.143 41.4580 42.5379 410.851 414.542 43.5979 44.6401 45.6665 425.562 418.222 421.894 Table A-7 (continued) 46.6786 429.229 47.6779 432.897 436.569 48.6656 49.6427 440.247 1.7446 1.7578 1.7708 1.7834 1.7958 1.8080 1.8200 1.8319 1.8435 1.8550 Saturation temperature, 20°C 26.0032 411.918 26.7900 415.977 27.5542 419.991 28.2989 423.970 29.0264 427.922 29.7389 431.852 30.4379 435.766 31.1250 439.668 31.8012 443.561 32.4678 447.450 Saturation temperature, 32°C 19.0907 417,648 19.7093 422.014 20.3062 426.310 20.8847 430.549 21.4471 434.743 438.900 21.9956 443.028 22.5318 23.0571 447.133 451.219 23.5726 24.0794 455.292 1.7246 1.7383 1.7517 1.7646 1.7774 1.7899 1.8021 1.8141 1.8258 1.8374 1.7182 1.7322 1.7458 1.7591 1.7719 1.7845 1.7968 1.8089 1.8207 1.8323 h, kJ/kg s, kJ/kg - K Saturation temperature, -10°C 401.555 65.3399 67.0081 404.983 68.6524 408.412 70.2751 411.845 415.283 71.8785 418.730 73.4644 75.0346 422.186 425.653 76.5904 1.7671 1.7800 1.7927 1.8052 1.8174 1.8295 1.8414 1.8531 Saturation temperature, 10°C 34.7136 408.835 35.6907 412.651 416.442 36.6454 420.215 37.5804 38.4981 423.974 39.4002 427.724 431.469 40.2884 41.1642 435.211 42.0286 438.954 Saturation temperature, 25°C 22.6242 413.289 23.3389 417.487 24.0306 421.627 24.7027 425.721 25.3575 429.779 25.9974 433.807 26.6239 437.813 27.2386 441.801 27.8427 445.777 1.7377 1.7511 1.7642 1.7769 1.7894 1.8017 1.8137 1.8256 1.8373 1.7183 1.7322 1.7458 1.7590 1.7718 1.7844 1.7967 1.8087 1.8206 Saturation temperature, 34°C 1.7099 1.7243 1.7382 1.7517 1.7647 1.7775 1.7899 1.8021 1.8141 1.8258 17.8590 416.325 18.4675 420.792 19.0526 425.174 429.487 19.6178 20.1660 433.747 20.6994 437.963 21.2199 442.143 21.7289 446.294 22.2278 450.424 454.535 22.7176 v, L/kg h, kJ/kg s, kJ/kg K Saturation temperature, 0°C 1.7518 1.7649 1.7777 1.7903 1.8026 1.8148 Saturation temperature, 15°C 405.361 47.1354 48.3899 408.969 416.159 49.6215 412.567 50.8328 52.0259 53.2028 29.9874 30.8606 419.649 423.339 410.430 414.362 31.7114 418.260 32.5427 422.133 33.3568 425.985 34.1556 429.823 34.9409 433.650 35.7139 437.470 Saturation temperature, 30°C 19.7417 414.530 20.3962 418.881 21.0272 423.159 21.6381 427.378 22.2316 431.549 22.8101 435.683 23.3733 439.787 23.9288 443.867 1.7120 1.7262 1.7400 1.7534 1.7664 1.7791 1.7915 1.8036 Saturation temperature, 36°C 17.2953 419.483 17.8708 423.961 18.4247 428.358 18.9603 432.690 19.4802 436.970 19.9865 441.207 20.4807 445.410 20.9643 449.586 21.4385 453.739 1.7162 1.7304 1.7442 1.7575 1.7704 1.7830 1.7954 1.8074 1.8193 1.7311 1.7556 1.7578 1.7707 1.7833 1.7956 1.8078 1.8197
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