Power-maximization of an irreversible simple Brayton cycle space nuclear power plant

Abstract

A simple Brayton cycle space power plant includes two parts: closed Brayton cycle with a compressor, a turbine and two heat exchangers, and radiator panel to dissipate heat to cosmic space. A model of simple irreversible closed Brayton cycle space power plant is established by utilizing finite-time thermodynamics herein, cycle thermal efficiency and cycle power output are deduced and optimized. When heat transfer areas of two heat exchangers and radiator panel are $F_H$ = $F_L$ = $15.7m^2$ and $F_R=122.4m^2$, and low temperature heat sink is $T_L$ = 490 $K$, cycle power of initial design scheme is $P$ = 33.72 $\text{kW}$. When three area distributions ($f_H$, $f_L$ and $f_R$) are optimized and $T_L$ = 490 $K$, the maximum cycle power is $P_{\max }$ = 34.75 $\text{kW}$, with an increase of about 3.05% compared with $P$. When $T_L$ is further optimized, the double maximum cycle power is $P_{\max ,2}$ = 39.45 $\text{kW}$, with an increase of about 13.53 % compared with $P_{\max }$, and an increase of about 17 % compared with $P$. The curve between $P_{\max }$ and the corresponding efficiency ${\eta }_{opt}$ is loop-shape one, that is, there is the maximum optimal efficiency ${\left({\eta }_{opt}\right)}_{\max }$ and the corresponding power output $P_{{\left({\eta }_{opt}\right)}_{\max }}$. The reasonable working range of irreversible plant should be $P_{{\left({\eta }_{opt}\right)}_{\max }}\le P\le P_{\max ,2}$ and ${\left({\eta }_{opt}\right)}_{P_{\max ,2}}\le \eta \le {\left({\eta }_{opt}\right)}_{\max }$.