Experimental comparison on performance characteristics of two carbon dioxide transcritical expander

Although CO2 transcritical cycle has been a most potential technology in replacement of working fluid, it has a low coefficient of performance compared with present conventional high performance refrigerant systems. So successful development Of CO2 expander to improve the coefficient of performance is still critical to the application Of CO2 system. In this study, the CO2 rolling piston expander was developed. The second expander was improved based on the first. Experiments were conducted on two CO2 transcritical expander in order to compare their performance properties and its influence on the whole system. The experimental results show that the efficiency of the expander is relational to its revolution speed and there exists an optimum value to reach the efficiency maximum. The performance of the second expander also was better than that of the first. And then the improving measures are effective.