The numerical study of the energy and exergy efficiencies of the micro-combustor by the internal micro-fin for thermophotovoltaic systems

Abstract

The use of micro-combustor for thermophotovoltaic systems requires that the energy conversion efficiency, exergy efficiency, and wall temperature be high and uniform. In this work, in order to improve the thermal performance of the micro-combustor, a new micro-fin is placed inside the micro-combustor in the outlet. The key parameter in the design, i.e., the length of the section containing the fin is investigated on the performance of the newly proposed micro-combustor. The hydrogen-air premixed combustion in a stoichiometric state is simulated numerically and the effect of the input speed, the thermal conductivity coefficient of the solid zone and the different heat transfer conditions from the exterior wall are investigated on the energy and exergy performances. The results showed that the micro-fin had a significant positive effect on the performance of the micro-combustor with micro-fin, by increasing the area exposed to heat transfer, thereby significantly increasing the mean wall temperature and uniformity. It also increases the energy conversion efficiency and exergy efficiency by increasing the radiation power. Increasing the micro-fin length, while increasing the thermal performance of the micro-combustor, also causes a little drop in pressure. The best performance is provided for the extended micro-combustor with the micro-fin for micro thermophotovoltaic systems.