Stirling Engine with Combustion in Porous Media

Abstract

Operation characteristics of a Sirling engine with combustion in a porous medium (regenerator) were investigated through one-dimensional numerical simulation. The porous medium was assumed to consist of fine spheres with a 0.1mm diameter and have a 98% porosity and a 15mm thickness. The compressed mixture is preheated by the porous medium and is ignited in the vicinity of its power-piston side end. The main reaction occurs in the gas phase, resulting in the increase in the gas temperature. The thermal efficiency becomes higher as the reaction zone is stabilized closer to the porous medium; then, if reaches the maximum, i.e., 57.5%, under the conditions of the revolution speed of 100rpm, the phase relation angle of 55deg., and the concentration of 2vol.% methane in air. With increasing concentration, the revolution speed attaining the maximum thermal efficiency is shifted to the high-speed side. The thermal efficiency higher than 55% was obtained over a range of the revolution speed from 50 to 250rpm.