Power and efficiency performance analyses for a closed endoreversible binary Brayton cycle with two isothermal processes

Adopting finite-time thermodynamics and building a model of closed endoreversible binary Brayton cycle with two isothermal processes, this paper derives analytical expressions of power output and thermal efficiency of the cycle. The influences of characteristic parameters of compressor pressure ratio, effectivenesses of the hot- and cold-side heat exchangers and effectivenesses of the ordinary regenerator and isothermal regenerator on the cycle performances are analyzed through detailed calculations. The results indicate that the maximum power output is achieved when the optimal pressure ratios of the topping and bottoming cycles are chosen, and the power output increases first and then decreases with the increase of pressure ratio of the topping cycle. The thermal efficiency of cycle gradually increases with the increase of pressure ratio of the topping cycle. It is also discovered that the power output and thermal efficiency of cycle increase by increasing effectivenesses of hot- and cold-side heat exchangers, ordinary regenerator, isothermal regenerator as well as heat reservoir temperature ratio of the cycle. The effects of effectivenesses of regenerators on power output obtained herein differ from those obtained based on classical thermodynamics. The results of this paper can provide some guidelines for the designs of new-type gas turbine plants.