An experimental comparative study of the effects on the engine performance of using three different motion mechanisms in a beta-configuration Stirling engine

This study deals with three different Stirling engines with rhombic, slider-crank, and bell-crank motion mechanisms which have been designed and manufactured. Engine performance tests of Stirling engines with these three different motion mechanisms at different operating parameters have been carried out in a laboratory environment. During the experimental studies under consideration, the cooler and heater temperatures have been kept at 300 K (+/- 5) and 1000 K (+/- 10), respectively. Engine performance tests have been performed at different charging pressures using helium, nitrogen, and air as working fluids. Despite the fact that the Stirling engines with these three different motion mechanisms have the same sweeping volumes and technical specifications, engine performance values have been obtained differently from each other. The main reason for this difference can be explained as friction and other mechanical losses in motion mechanisms. The performance values obtained depending on the type of motion mechanism are rhombic, slider-crank, and bell-crank, from highest to lowest, respectively. The highest engine power measured among all experimental studies has been 215.48 W at 550 rpm and 4 bar charging pressure in tests using helium gas and rhombic motion mechanism. The lowest engine power among the maximum power values has been obtained as 82.5 W at 167 rpm and 4 bar charging pressure in experiments using air as the working fluid and the bell-crank motion mechanism. As a matter of fact, the highest engine power within the maximum engine power values is 161.2% higher than the lowest engine power.