Keywords: CO2 transcritical cycle, expander, expansion process, rolling piston
The development of CO2 expander technology in CO2 transcritical cycles
In this study, the CO2 expansion process in CO2 transcritical cycles is analysed by taking a typical operation condition as an example. The expansion work is divided into two parts: the first is the work done mainly by pressure potential energy without the phase change, and the second is the work done mainly through the volume expansion of the two-phase fluid. According to the process, the ideal expander requirement was given. By the comparison and evaluation of many types of expander, the rolling piston was identified for our initial development due to its low cost, wide application, and reasonable efficiency. The rolling piston efficiency was analysed and the inlet fluid control methods were discussed.