40_Lessons_on_Refrigeration_and_Air_Conditioning_www.hvac-eng.ir_119

40_Lessons_on_Refrigeration_and_Air_Conditioning_www.hvac-eng.ir_119

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Version 1 ME, IIT Kharagpur 25 COP NH3,1st = 1.363 Power input to single stage ammonia system is given by: W c,NH3,1st = Q e / COP NH3,1st = 35.17/1.363 = 25.8 kW (Ans.) Comments: 1) Using a cascade system the power consumption could be reduced by about 9.5 %. 2) More importantly, in actual systems, the compared to the single stage system, the compressors of cascade systems will be operating at much smaller pressure ratios, yielding high volumetric and isentropic efficiencies and lower discharge temperatures.
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