Power optimization of an irreversible closed intercooled regenerated brayton cycle coupled to variable-temperature heat reservoirs

Abstract

In this paper, power is optimized for an irreversible closed intercooled regenerated Brayton cycle coupled to variable-temperature heat reservoirs in the viewpoint of the theory of thermodynamic optimization (or finite-time thermodynamics (FTT), or endoreversible thermodynamics, or entropy generation minimization (EGM)) by searching the optimum intercooling pressure ratio and the optimum heat conductance distributions among the four heat exchangers (the hot-and cold-side heat exchangers, the intercooler and the regenerator) for fixed total heat exchanger inventory. When the optimization is performed with respect to the total pressure ratio of the cycle, the maximum power is maximized twice and the double-maximum power is obtained. Further, as the optimization is performed with respect to the thermal capacitance rate matching between the working fluid and the heat reservoir, the double-maximum power is maximized again and a thrice-maximum power is obtained. In the analysis, the heat resistance losses in the four heat exchangers, the irreversible compression and expansion losses in the compressors and the turbine, the pressure drop loss in the piping, and the effects of finite thermal capacity rate of the three heat reservoirs are taken into account. The effects of the heat reservoir inlet temperature ratio, the total heat exchanger inventory and some other cycle parameters on the cycle optimum performance are analyzed by a numerical example. The optimum results are compared with those reported in recent reference for the conceptual design of a closed-cycle intercooled regenerated gas turbine nuclear power plant for marine ship propulsion. The numerical example shows that the method herein is valid and effective.