Power density optimisation of an endoreversible closed variable-temperature heat reservoir intercooled regenerated Brayton cycle

SYNOPSIS Taking power density, defined as the ratio of power output to the maximum specific volume in the cycle, as the objective function, this paper applies the theory of finite time thermodynamics to find the optimal distribution of heat conductance of the hot- and cold-side heat exchangers, the optimal intercooling pressure ratio, the optimal total pressure ratio and the optimal heat capacity ratio between working fluid and heat reservoir of an endoreversible closed intercooled regenerated Brayton cycle coupled to variable-temperature heat reservoirs with heat resistance losses in the hot- and cold-side heat exchangers, the intercooler and the regenerator, by using detailed numerical calculation. The maximum power density, the double-maximum power density and the triple-maximum power density are obtained by optimisation. The effects of some design parameters, including the cycle inlet heat reservoir temperature ratio, the inlet temperature ratio of cooling fluid in the intercooler and the cold-side heat reservoir, and the total heat exchanger inventory, on the maximum power density and the corresponding efficiency, optimum intercooling pressure ratio, and optimum heat conductance distributions between the hot- and cold-side heat exchangers, the double-maximum power density and the corresponding efficiency and optimum total pressure ratio, as well as the triple-maximum power density, are analysed.