Hot exhaust gas flows out of an engine at 377°C and 140 kPa at a rate of 1.5 kg/s. The gas (exhaust gas) is used to produce saturated steam at 175°C in a thermally insulated heat exchanger. Liquid water enters from the surroundings at 20°C and 101 kPa. The temperature of the exhaust gas is 277°C at the outlet of the heat exchanger. You may treat the exhaust gas as air behaving as an ideal gas. Use constant specific heat capacities at the average temperature (for the exhaust gas). You may neglect any pressure changes in the exhaust gas pipe. Tasks: a) Calculate the steam production rate in kg/s (i.e., the mass flow rate of water through the heat exchanger).b) Calculate the entropy generation rate in the heat exchanger in kW/K.c) Calculate the second-law efficiency of the heat exchanger.
Hot exhaust gas flows out of an engine at 377°C and 140 kPa at a rate of 1.5 kg/s. The gas (exhaust gas) is used to produce saturated steam at 175°C in a thermally insulated heat exchanger. Liquid water enters from the surroundings at 20°C and 101 kPa. The temperature of the exhaust gas is 277°C at the outlet of the heat exchanger. You may treat the exhaust gas as air behaving as an ideal gas. Use constant specific heat capacities at the average temperature (for the exhaust gas). You may neglect any pressure changes in the exhaust gas pipe.
Tasks:
a) Calculate the steam production rate in kg/s (i.e., the mass flow rate of water through the heat exchanger).
b) Calculate the entropy generation rate in the heat exchanger in kW/K.
c) Calculate the second-law efficiency of the heat exchanger.
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