A refrigerator works using a two-stage cascade system. Each of the cycles uses the same refrigerant R134a. The low-temperature cycle operates between the pressures of 14.5 psia and 50 psia. The high-temperature one – between 50 psia and 100 psia. The flow rate in the high-temperature cycle is 50 lbs/min. Assume both cycles as ideal vapor-compression cycles and no losses in the heat transfer between the cycles. Answer the following questions:(a) Calculate the flow rate in the low-temperature cycle. (b) Calculate the rate of heat removal from the refrigerated unit.(c) What is the power input needed for the compressors?(d) What is the COP?(e) Compare the COP of this system with a single vapor-compression cycle operation in the same pressure range.(d) [narrative] Discuss the pros and cons of the cascade refrigeration system.Use the attached P H diagram to solve this problem.
A refrigerator works using a two-stage cascade system. Each of the cycles uses the same refrigerant R134a. The low-temperature cycle operates between the pressures of 14.5 psia and 50 psia. The high-temperature one – between 50 psia and 100 psia. The flow rate in the high-temperature cycle is 50 lbs/min. Assume both cycles as ideal vapor-compression cycles and no losses in the heat transfer between the cycles. Answer the following questions:(a) Calculate the flow rate in the low-temperature cycle. (b) Calculate the rate of heat removal from the refrigerated unit.(c) What is the power input needed for the compressors?(d) What is the COP?(e) Compare the COP of this system with a single vapor-compression cycle operation in the same pressure range.(d) [narrative] Discuss the pros and cons of the cascade refrigeration system.Use the attached P H diagram to solve this problem.
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