Efficient power analysis and five-objective optimization for a simple endoreversible closed Brayton cycle

Abstract

Based on a simple endoreversible closed Brayton cycle model established in the previous literature, this paper performs thermodynamic analyses and multi-objective optimizations by applying finite-time thermodynamics and NSGA-II. Cycle efficient power expression of the cycle is derived and analyzed. Heat exchanger heat conductance distribution and cycle pressure ratio are used as optimization variables, and cycle power output, ecological function, thermal efficiency, power density and efficient power are taken as optimization goals. The results obtained with LINMAP, TOPSIS and Shannon Entropy decision-making methods used in five-objective optimization are compared with those of five single-objective optimizations. The results show that efficiency at the maximum efficient power is higher than that at the maximum power; there are an optimal values of heat conductance distribution and pressure ratio make efficient power reaches the maximum; in the five-objective optimization, deviation indices with LINMAP, TOPSIS and Shannon Entropy decision-making methods are 0.2443, 0.2443 and 0.2400, respectively, deviation index with Shannon Entropy approach is the smallest, and the result is closer to ideal scheme; while the deviation indices for five single-objective optimizations with power, efficiency, ecological function, power density and efficient power are 0.4111, 0.6750, 0.2651, 0.2443 and 0.2400, respectively.

Keywords

• Endoreversible closed brayton cycle
• Optimal pressure ratio
• Optimal heat conductivity distribution
• Multi-objective optimization
• NSGA-II algorithm
• Finite-time thermodynamics