Investigations on Performance of Stirling Engine Regenerator Matrix Available to Purchase

Stirling engine technology has attracted attention due to recent environmental and energy problems. The regenerator is the main component in high efficiency Stirling engines. A suitable regenerator must be designed for each Stirling machine to provide high performance. The aim of the present work is to find a feasible number of screens in regenerator by taking into account the pressure drop, dead volume, the thermal penetration depth and geometry of regenerator. The second order cyclic analysis with realistic assumptions is carried out for a single cylinder, beta Stirling engine with rhombic drive for predecided operating conditions, such as pressure of 30 bar, hot side temperature of 750 K, speed of 1440 rpm and hydrogen as the working fluid. It is intended to design and develop the Stirling engine with capacity ≥ 1.5 kW_e and the efficiency of drive mechanism and alternator is assumed as 85% each. Miyabe’s and Martini’s approaches are used to simulate regenerator performance considering non-sinusoidal motion of displacer and piston. The results reveal that the flow loss increases remarkably to attain higher value of regenerator effectiveness. However, increase in the speed results into an increase in the mass flow rate of the working fluid. It is observed that regenerator effectiveness decreases only marginally over the range of speeds considered. It is also ensured for selected regenerator screen that the thermal penetration depth (239 μm) should be greater than wire radius of mesh (20.5 μm). For present set of operating and geometrical parameters, length of regenerator is fixed as 22 mm which gives regenerator effectiveness as 0.965. Further, the practice to fill more screens than the designed number of screens in the regenerator, while assembling is not advantageous. It increases pressure drop which results in reduced power output. These are some of the important conclusions.