A novel hybrid pyroelectric-Stirling engine power generation system

Abstract

Temperature fluctuations in the thermal regenerator of Stirling Engine SE occur at relatively high frequencies, making them amenable to direct harvesting using Pyroelectric materials. This paper demonstrates the technical feasibility of a novel hybrid Stirling Engine (SE), coupled with inserted pyroelectric generators in its thermal regenerator, to produce extra power through the pyroelectric effect and increase engine performance. Theoretical models have been constructed to analyze the performance of the pyroelectric-Stirling engine (P-SE) system and determine its advantages over conventional SEs. The transient thermal behavior of the pyroelectric regenerator is modeled by subdividing it into multiple lumped sub-regenerators. Replacing the metal regenerator in a conventional SE at 750 K hot chamber temperature with a pyroelectric regenerator increased power production by 2.9%. Furthermore, at 25 Hz fluctuation, 15 mm regenerator length, and regenerator porosity of 0.6, the system efficiency of the hybrid P-SE system increased by 0.5% and 3.5% compared to systems using steel and aluminum regenerators, respectively. Also, the P-SE system operating at 25 Hz yields the highest combined efficiency of 49.8% at the regenerator porosity of 0.6.