In this paper, four possible design variants of the Revolving Vane expander have been examined in relation to their application when using CO 2 as the working fluid in a refrigeration cycle. The detailed examination of the design components and illustrations are presented and discussed. The study shows that the Revolving Vane expander RV-I design configuration with the vane attached to the rotor and in which the rotor is also used as the driving component is the most superior design. It is found to have the highest mechanical efficiency and the most desirable variation of the power produced.