The influence of the intermediate channel of CO2 two-cylinder rolling piston expander on efficiency and expansion ratio is investigated in this paper. The channel is improved by decreasing its diameter and length at the same time. The experiment of the improved expander is carried out in this paper. 26℃
6.5MPa is the optimum work condition of the test. The recovered power of the expander is up to 200W and the efficiency is 42.3%. The expander ratio has already gone to 2.2
which is very close to the theoretical ratio 2.5. However
there is still the room for improvement of the expander.