Determine the heat transfer area requirements of Problem 8.41 if a 1-2 shell and tube, an unmixed crossflow, and a parallel flow heat exchanger are used, respectively. From Problem 8.41: A regenerator is used in a gas turbine power plant to preheat the air before it enters the combustor. The air leaves the compressor at a temperature of 350?C. Exhaust gas leaves the turbine at 700?C. The mass flow rates of air and gas are 5 kg/s. Take the cp of air and gas to be equal to 1.05 kJ/(kg K). Determine the required heat transfer area as a function of the regenerator effectiveness, if the overall heat transfer coefficient is 75W/(m2 K).GIVENAn air-to-gas heat exchangerEntering temperaturesTa,in = 350?CTg,in = 700?CMass flow rates: ma = mg = 5 kg/sSpecific heats: cpa = cpg = 1.05 kJ/(kg K) = 1050 J/(kg K)Overall heat transfer coefficient (U) = 75 W/(m2 K)ASSUMPTIONSFor case (a) the air is in thetubes

Transcribed Image Text:

Tain = 700°C Gas Air Tan = 350°C Case (a) Gas Tain = 700°C Gas Tain = 700°C Air Tain = 300°C Tain = 350°C Air Case (c) Case (b)