WEAR BEHAVIOUR OF VANES FOR A ROTARY VANE EXPANDER WITH VARIOUS GRAPHITE MATERIALS UNDER DRY SLIDING CONDITIONS

Abstract

This study presents tribological properties of various graphite materials of vanes for rotary vane expanders. A test device was developed in order to measure the wear and power dissipation under conditions similar to a real operation of a vane expander. Subsequently, the friction coefficients of vanes for a rotary vane expander were evaluated. Parameters of the test device are based on the vane expander used for an experimental organic Rankine cycle unit. Four materials in total were tested: graphite, antimony-impregnated graphite, 2D carbon fibre-reinforced graphite, and 2.5D carbon fibre-reinforced graphite. Wear tests were performed under dry sliding conditions at the temperature of 115 °C and at 3030 rpm for the total time of about 400 hours. The method of evaluating the wear involved measuring the vane weight loss in relation to the duration of the load. Furthermore, specific wear coefficients were established in order to evaluate the tribological properties of the tested materials. Measurements have shown that carbon fibre materials are the most advantageous in terms of wear. The best friction properties were obtained for the pure graphite.