Heat Transfer Enhancement and Exergy Efficiency Improvement of a Micro Combustor with Internal Spiral Fins for Thermophotovoltaic Systems

Abstract Targeting at addressing the low exergy efficiency of micro thermophotovoltaic (MTPV) system, a novel micro combustor with internal spiral fins is proposed. The geometrical parameters, including internal spiral fin number, length and pitch distance, on the thermal performance and exergy efficiency are numerically investigated. The introduction of internal spiral fins can effectively improve the exergy efficiency and energy output of MTPV system, but with higher pressure loss. The results show that the micro combustor with 8 spiral fins exhibits the highest exergy efficiency of 66.9%, which is 6.9% higher than that of the conventional one at the inlet velocity of 5 m/s. Moreover, the micro combustor with 8 spiral fins obtains the highest energy output is 5.01 W at inlet velocity of 8 m/s. Taking the pressure loss into consideration, the optimal internal spiral fins length of 10 mm is suggested.