Comparative study on the performance of different drive mechanisms used in a beta type Stirling engine through thermodynamic analysis

Abstract

In this study, thermodynamic and kinematic analyses of bell crank, slider crank, rhombic and scotch yoke drive mechanisms were performed for a beta type Stirling engine with a swept volume of 365 cm3. The kinematic analyses of Stirling engines with these different drive mechanisms were investigated by using the MSC Adams program, and the pressure-volume variations depending on the crankshaft angle were determined by using the isothermal analysis method. It was determined that compression and expansion volume values of rhombic drive mechanism were close to each other, while compression volume value was extremely higher than expansion volume value in other drive mechanisms. For this reason, in this research conducted with working fluid of equal amount (m=0.000716 kg), for all of drive mechanisms, it was determined that engine with rhombic drive mechanism generates 19.2% net work more than the other drive mechanism. The masses of working fluid used in 1 bar charge pressure from engines with bell crank, slider crank, rhombic and scotch yoke drive mechanism were 0.000716 kg, 0.000737 kg, 0.000536 kg and 0.000724 kg, respectively. The net work amounts obtained as a result of the thermodynamic analyses made for the 1 bar charge pressure value in bell crank, slider crank, rhombic and scotch yoke drive mechanisms are 12.85 J, 12.44 J, 11.61 J and 13.05 J, respectively. In this research conducted with working fluid in the same charge pressure, it was determined that 10.8% less net work was obtained from engine with rhombic drive mechanism. Since all the changes of the volume in the bell crank, slider crank and scotch yoke drive mechanisms are very close to each other, the net work performance values obtained with the equal amount of working fluid and the same charge pressure values are also very close to each other.