Off-design and control performance analysis of a novel supercritical carbon dioxide power cycle for waste heat recovery

Abstract

A novel supercritical carbon dioxide power cycle (sCO2) for waste heat recovery (WHR) is developed. This novel cycle has high efficiency, and it could make a more complete utilization of the waste heat. Besides, the flexible and independent controls of recompression compressor and main compressor can be made to obtain the better off-design performance. The off-design and control performance of this system is quantitatively investigated in this paper. The results indicate that the optimal net power output increases as mass flow rate or temperature of flue gas increases, whereas it decreases with increasing ambient temperature. The first and second highest exergy destruction shares always belong to the cooler and LTWHE under various external conditions. The adjustment of two compressor outlet pressures should be a priority under various mass flow rates or temperatures of flue gas, while the adjustment of cycle minimum pressure should be given a high-priority rating in response to variation of ambient temperature. Moreover, the control performance of recompression compressor is more sensitive to the variation of flue gas mass flow rate, while the control performance of main compressor is more sensitive to the variation of flue gas temperature and ambient temperature.