Experimental study on regenerative effectiveness and flow characteristics of parallel-plate regenerator in Stirling engine

Abstract

Regenerator is the critical component of the Stirling engine. Its performance directly affects the efficiency of the whole engine. The heat transfer and flow characteristics of the parallel-plate regenerator (PPR) are experimentally investigated, and the influences of material and geometric parameters on regenerative effectiveness and pressure drop are obtained. The results show that the axial heat conduction will reduce the regenerative effectiveness of the PPR. The higher the thermal conductivity of the plate, the lower the regenerative effectiveness. Larger plate thickness and smaller plate length will also increase the axial heat conduction loss. The PPR shows good flow characteristics. The comparative experiment with the wire mesh regenerator shows that its friction coefficient is much lower than that of the wire mesh regenerator. Through the comprehensive index NPH/NTU defined as the ratio of number of pressure heads (NPH) to number of transfer units (NTU), the overall performances of PPR and wire mesh regenerator are compared. The results show that the PPR has better working performance. To reduce the adverse effect of axial heat conduction on the PPR, the optimization experiment was carried out by segmenting the regenerator into several sections. The results show that the regenerative effectiveness of the segmented PPR is increased by 20%, while the increase of pressure drop is within an acceptable range.