We have a refrigeration unit that works at a pressure of 0.1MPain the evaporator and 1 MPa in the condenser. The refrigeration unit uses a compressor with an efficiency of 90% and a turbine with 100% efficiency is used to expand the refrigerant after the

condenser.

a) What is the coefficient of performance for this refrigeration unit?

b) Above what outside (ambient) temperature will you start having problems with heat rejection from the condenser? Assume the refrigeration unit uses a vapour-compression cycle and HCF-134a (also called R-134a) as the refrigerant.

Assume that the exit of the condenser is 100% saturated liquid and the exit of the evaporator is 100% saturated vapor.