Study on the COP of free piston Stirling cooler (FPSC) in the anti-sublimation CO2 capture process

Free piston Stirling cooler (FPSC) is a promising alternative for the conventional coolers and has been applied to various fields. In the previous research, a novel cryogenic CO2 capture system based on FPSCs has been exploited. In order to enhance the cryogenic CO2 capture efficiency, the investigation on the coefficient of performance (COP) of the FPSC is carried out in this work. In detail, the influence of different materials (aluminium and copper), size of cold head (length and diameter), as well as ambient conditions (humidity and temperature) on the COP of the cryogenic system were tested. The experiment results indicate that the material of cold head should be selected at copper to increase the COP of CO2 capture system. The length and diameter of cold head should be short and thick. In addition, the low ambient temperature is benefit for the high COP. For the optimal conditions (the material was copper, length and diameter were 180 and 40 mm, respectively), the temperature of the cold head reached −140 °C, and the COP of the FPSC and the cryogenic CO2 system was 0.82 and 0.70, respectively.