A vapor-compression refrigeration system circulates R-134a at a rate (m) of 10 kg/min. The refrigerant enters the compressor at - 10oC, 1.2 bar and exits at 7 bar. The isentropic compressor efficiency is 68%. There are no significant pressure drops as the refrigerant flows through the condenser and evaporator. The refrigerant leaves the condenser at 7 bar and 24oC. Ignoring the heat transfer between the compressor and its surroundings, determine
(a) The refrigerating capacity in tons and
(b) The coefficient of performance (COPR),
(c) The irreversibility rates of the compressor and expansion valve each in kW for an ambient temperature of 20oC.