Controlling effect of phase change material based heat exchanger on supercritical CO2 Brayton cycle

Supercritical carbon dioxide (SCO2) Brayton cycle is widely known as highly potential bottoming cycle among energy conversion systems in the future due to its low requirement to heat source, high efficiency and small volume. Recently, SCO2 Brayton cycle has been considered utilized in marine industry. In marine environment, unstable disturbance due to the oscillating condition driven by wind and waves makes an impact to on the dynamic performance of SCO2 Brayton cycle. In this study, we proposed a novel type of compact heat exchanger coupled with phase change material (PCM) based on the concept of printed circuit heat exchanger (PCHE) as a transient controlling method in order to stabilize the dynamic performance of main compressor, re-compressor and turbine in the SCO2 recompression Brayton cycle system. In this paper, dynamic modelling of the SCO2 recompression Brayton cycle system with designed PCM based heat exchanger is developed and its dynamic performance is tested. The result of the transient simulation shows that with the effect of PCM based heat exchanger, the disturbing ranges of compression and expanding power of the main compressor, re-compressor and turbine decrease at most by 84%, 75%, and 95% respectively, and the disturbing range of efficiency is reduced by 94%. The PCM based heat exchangers are proved to have great effect on reducing disturbing amplitude of performance of turbo machineries and cycle parameters.