A refrigeration system operates on the ideal vapor-compression refrigeration cycle with ammonia as the refrigerant. The evaporator and condenser pressures are 200 kPa and 2000 kPa, respectively. The temperatures of the low-temperature and high-temperature mediums are 29oC and 27oC, respectively. If the rate of heat rejected in the condenser is 18.0 kW, determine
(a) The volume flow rate of ammonia at the compressor inlet, in L/s.
(b) The power input and the COP.
(c) The second-law efficiency of the cycle and the total exergy destruction in the cycle. The properties of ammonia at various states are given as follows:
h1 = 1439.3 kJ/kg, s15 =.8865kJ/kg·K, v1 = 0.5946 m3/kg, h2 = 1798.3 kJ/kg, h3 = 437.4 kJ/kg, s3 = 1.7892kJ/kg·K, s4 = 1.9469kJ/kg·K.
state 1: compressor inlet, state 2: compressor exit, state 3: condenser exit, state 4: evaporator inlet.