Question

A heat exchanger employs 1.5kg/s of a liquid whose specific heat is 5kJ/(kg K) at 15o C to cool 5kg/s of air from 120o C to 25o C. The air pressure during this cooling process remains constant at 100kPa.

asked Jun 5, 2021 76.2k views

A heat exchanger employs 1.5kg/s of a liquid whose specific heat is 5kJ/(kg K) at 15o C to cool 5kg/s of air from 120o C to 25o C. The air pressure during this cooling process remains constant at 100kPa. The air leaving the heat exchanger enters an isentropic compressor where it is compressed to 1000kPa. Find the temperature of the air leaving the compressor. If the liquid leaves the heat exchanger at 20o C, how much is the external heat transfer rate to the ambient from the heat exchanger? What is the power required to drive the compressor? What is the irreversibility rate in the heat exchanger? Assume the ambient temperature to be 25o C and that air is an ideal gas with constant specific heats and use a value of 1.004kJ/(kg K) for Cp,o and 0.717kJ/(kg K) for Cv