(52c) A Heat-Recirculating Combustor Using SiC Porous Foam for Thermophotovoltaic Power Devices

Efficient and reliable portable power devices have been investigated due to the increasing demand of electronic devices. Because of the advantage of the high energy density, power systems using the combustion of hydrocarbon fuels are considered as one alternative to replace secondary batteries. A thermophotovoltaic (TPV) power system, which is one of the combustion-driven power systems, converts thermal energy to electricity through photons. The TPV power systems consist of simple structure and have high efficiency without friction loss by moving parts. To enhance the efficiency of the TPV systems, several design factors are important: stable burning in the combustor as a heat source and high enough temperature of the emitter as a radiation source. In this study, to improve the performance of the combustor that was developed for TPV power devices in a previous study, silicon carbide (SiC) porous foam is inserted into a combustion chamber. Porous burners have been considered as one possible technology for achieving the high-efficiency by increasing residence time for complete combustion and enhancing internal heat recirculation. To evaluate the combustor performance, combustion stability limits and temperature distribution along the emitter wall surface are measured. Compared with the case without SiC porous foam in the combustion chamber, the flame stability limits are extended with SiC porous foam, implying a widened operating range of the combustor. The temperature of the emitter wall surface is locally enhanced where SiC porous foam is installed, and the average temperature of the emitter wall also increases when SiC porous foam is used.