A vapor-compression air conditioning system operates at steady state as shown in Fig. P10.26. The system maintains a cool region at 608F and discharges energy by heat transfer to the surroundings at 908F. Refrigerant 134a enters the compressor as a saturated vapor at 408F and is compressed adiabatically to 160 lbf/in.2 The isentropic compressor efficiency is 80%. Refrigerant exits the condenser as a saturated liquid at 160 lbf/in.2 The mass flow rate of the refrigerant is 0.15 lb/s. Kinetic and potential energy changes are negligible as are changes in pressure for flow through the evaporator and condenser. Determine
(a) the power required by the compressor, in Btu/s.
(b) the coefficient of performance.
(c) the rates of exergy destruction in the compressor and expansion valve, each in Btu/s.
(d) the rates of exergy destruction and exergy transfer accompanying heat transfer, each in Btu/s, for a control volume comprising the evaporator and a portion of the cool region such that heat transfer takes place at TC 5 5208R (608F).
(e) the rates of exergy destruction and exergy transfer accompanying heat transfer, each in Btu/s, for a control volume enclosing the condenser and a portion of the surroundings such that heat transfer takes place at TH 5 5508R (908F).
Let T0 5 5508R.