Current automotive air conditioners use R134a as a working fluid. Assume an evaporator temperature of 0C (in practice, this would be just above freezing, to prevent ice buildup) and a condenser temperature of 40C (needs to be able to exhaust heat into the hot summer air). In this problem, neglect the finite compressor efficiency.
a) Carry out a simple thermodynamic analysis of this process: find the operating pressures in the evaporator and condenser, sketch the cycle on a PH diagram, find the heat flows QH and QL and work done W. Present your results in a table (units kJ/kg). Compute the COP, and compare to the Carnot COP.
b) Now assume the compressor e?ciency is 75 percent. Determine the new COP.