A study has been conducted to compare the performances of the four novel RV (revolving vane) expander design variants at suction pressures of between 2 and 30 bars, a constant discharge pressure of 1 atm and operating speeds of between 600 and 1800 rev min(-1). The aspects considered were the mechanical, volumetric and overall performances of the machines. From the study, it was found that the RV-II expander, where the vane is fixed to the cylinder and the cylinder is the driving component, is the most preferred mechanism across the operating range studied here. The RV-I mechanism, where the vane is fixed to the rotor and the rotor is used as the driving component, is the least preferred. On average, the overall efficiency of RV-II is 10% higher than that of RV-I while at a certain condition, RV-II can be more than 65% better than RV-I. (C) 2014 Elsevier Ltd. All rights reserved.