Investigation of CH4 and porous media addition on thermal and working performance in premixed H2/air combustion for micro thermophotovoltaic

Abstract

Primary obstacles to the development of micro-thermoelectric generators are the gigantic heat loss ratio and flame instability. Premixed H2/air combustion in the micro-planar combustor with porous media (PM) and CH4 blended is experimentally and numerically conducted to boost the generator working performance. Effects of porosities, PM length and CH4 blending on combustion characteristics and thermal performance are detailedly studied at various operating conditions. Results indicate that flame stability is enhanced in PM, and the burner radiation temperature is also significantly boosted because of heat recirculation and heat transmission from flame. PM porosity ε = 0.9 balances the effects of solid skeleton on flame propagation and thermal improvement, which is conducive to flame stabilization. The coupling of PM setting and 25 % CH4 blending strongly improves the combustor thermal performance via altering the flame location and enhancing heat transmission. It also ameliorates the uniformity of radiation wall. Moreover, prolonging porous matrix has a positive effect on the improvement of thermal performance under a high chemical energy input. Particularly, combustor #C-Ls13 obtains an electrical output of 2.5 W and a system efficiency of 2.1 % at 25 %CH4-75 %H2 fueled combustion.