Exergetic performance optimization of an endoreversible intercooled regenerated Brayton cogeneration plant. Part 2: Exergy output rate and exergy efficiency optimization

Abstract

The exergy output rate and exergy efficiency performances of an endoreversible intercooled regenerative Brayton cogeneration plant are optimized based on the model which is established using finite time thermodynamic in Part 1 of this paper. It is found that the optimal heat conductance allocation of the regenerator is almost zero. When the total pressure ratio and the heat conductance allocation of the regenerator are fixed, it is shown that there exist two optimal intercooling pressure ratios, and two optimal groups of the heat conductance allocations among the hot-, cold- and consumer-side heat exchangers and the intercooler, which correspond to a maximum dimensionless exergy output rate and a maximum exergy efficiency. When the total pressure ratio is variable, there exist two optimal total pressure ratios which correspond to a double-maximum dimensionless exergy output rate and a double-maximum exergy efficiency, also the corresponding exergy efficiency and exergy output rate are obtained. The effects of the total heat exchanger conductance and the consumer-side temperature on the double-maximum dimensionless exergy output rate and the double-maximum exergy efficiency are discussed. It is found that there exists an optimal consumer-side temperature which correspond to a thrice- maximum dimensionless exergy output rate, and the intercooling process is not necessary by taking exergy efficiency as the objective when the consumer-side temperature is high.