An ammonia-water absorption refrigeration cycle is used to

Chapter 11, Problem 87P

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Problem 87P

An ammonia-water absorption refrigeration cycle is used to keep a space at 25°F when the ambient temperature is 70°F. Pure ammonia enters the condenser at 300 psia and 140°F at a rate of 0.04 lbm/s. Ammonia leaves the condenser as a saturated liquid and is expanded to 30 psia. Ammonia leaves the evaporator as a saturated vapor. Heat is supplied to the generator by geothermal liquid water that enters at 240°F at a rate of 0.55 lbm/s and leaves at 200°F. Determine (a) the rate of cooling provided by the system, in Btu/h, the COP, and (b) the second-law efficiency of the system. The enthalpies of ammonia at various states of the system are: condenser inlet h2 = 665.7 Btu/lbm, evaporator inlet h4 = 190.9 Btu/lbm, evaporator exit h1 = 619.2 Btu/lbm. Also, take the specific heat of geothermal water to be 1.0 Btu/lbm•°F.