Consider a cascade system that uses Carnot refrigeration for the high temperature cycle, and vapor compression refrigeration for the low temperature cycle. Saturated vapor ammonia enters the compressor in the low temperature cycle at 20 psi and exits at 90 psi as it enters the heat exchanger. R134a enters the compressor in the high temperature cycle at 20oF and a quality of 0.84, and exits at 120 psi. Sat. liquid then enters the turbine at 120 psi, which is then expanded to a mixture of quality 0.25. Given a refrigeration capacity of 10 tons, determine:
Ratio of the mass flow rate of ammonia to R134a
Power input/output of each compressor and turbine (hp)
Coefficient of performance