EXAMPLE 6 A household refrigeration system works with a vapor compression refrigeration system with two evaporators using Refrigerant 134a as the working fluid. This arrangement is used to achieve refrigeration at two different temperatures with a single compressor and a single condenser. The low temperature evaporator operates at -18°C with saturated vapor at its exit and has a refrigerating capacity of 10.5 kW (3 tons). The higher- temperature evaporator produces saturated vapor at 3.2 bar at its exit and has a refrigerating capacity of 7 kW (2 tons). Compression is isentropic to the condenser pressure of 10 bar. There are no significant pressure drops in the flows through the condenser and the two evaporators, and the refrigerant leaves the condenser as saturated liquid at 10 bar. Calculate (a) the mass flow rate of refrigerant through each evaporator, in kg/min. (b) the compressor power input, in kW. (c) the rate of heat transfer from the refrigerant passing through the condenser, in kW