Optimization of a novel drive mechanism approaching the ideal cycle for beta type Stirling engines

Stirling engines are capable in the renewable energy gain and the recovery of waste heat, both of which are important issues today. Existing studies revealed that the piston trajectories convergent to the Stirling cycle provide more power than traditional crank mechanism. In this study, a hypocycloid drive mechanism not used in the literature was optimized on the ideal piston trajectories for beta type Stirling engines. Optimization was realized to improve the isochoric heating and cooling processes as well as the isothermal compression and expansion. The cyclic work was treated as another objective succession. The optimal results taking into account these five objectives were obtained with the gear ratios of 5 and 4 for displacer piston and power piston, respectively. The piston dwells provided the enough objective succession not only for the both isochoric processes but also for the isothermal compression process, while failed in the isothermal expansion. In comparison with crank mechanism, a cyclic work increment of 10% was achieved in the near-ideal piston trajectories, but the maximum increment of 14% eventuated in some out of ideal.