Optimal structure design of supercritical CO2 power cycle for gas turbine waste heat recovery: A superstructure method

Abstract

The supercritical CO2 power cycle is an effective way for gas turbine waste heat recovery due to its compact system structure and high efficiency. The stepwise optimization of operating parameters and system structure in the early research results in a great limitation of the search space on the optimal structure, consequently, there are still huge challenges in determining the optimal structure of the supercritical CO2 power cycle for waste heat recovery. Therefore, this study proposed a new superstructure of supercritical CO2 cycle for waste heat recovery based on the concept of splitting, which could optimization system structure and design parameters simultaneously. Taking the net power output as the objective function, the optimal structure of supercritical CO2 cycle under different boundary conditions and equipment parameters are investigated. The results show that the superstructure method produces new cycle structures which are not reported before, which is mainly embodied in the flow split and compression structure of the cold end. Compared with traditional supercritical CO2 and steam Rankine cycles at the heat source temperature of 400–600 °C, the maximum net power output obtained by the superstructure method are increased by 4.09–6.94% and 11.65–21.23%, respectively.