Consider an ideal two-stage refrigeration system that uses R-12 as the working fluid. Saturated liquid leaves the

Question:

Consider an ideal two-stage refrigeration system that uses R-12 as the working fluid. Saturated liquid leaves the condenser at 40oC and is throttled to -20oC. The liquid and vapor at this temperature are separated, and the liquid is throttled to the evaporator temperature at -70oC. Vapor leaving the evaporator is compressed to the saturation pressure corresponding to -20oC, after which it is mixed with the vapor leaving the flash chamber. Determine
The coefficient of performance (COPR) of the system.