A cascade system is composed of two ideal refrigeration cycles, as shown in Fig. 9.28. The high

Question:

A cascade system is composed of two ideal refrigeration cycles, as shown in Fig. 9.28. The high temperature cycle uses R-410a. Saturated liquid leaves the condenser at 40◦C, and saturated vapor leaves the heat exchanger at −20◦C. The low temperature cycle uses a different refrigerant, R-23. Saturated vapor leaves the evaporator at −80◦C, h = 330 kJ/kg, and saturated liquid leaves the heat exchanger at −10◦C, h = 185 kJ/kg. R-23 out of the compressor has h = 405 kJ/kg. Calculate the ratio of the mass flow rates through the two cycles and the COP of the system.