Numerical Investigations on the Emitter Power and Energy Conversion Efficiency Improvement of Micro‐cylindrical Combustor by an Internal Spiral Fin for Micro‐thermophotovoltaic Systems

Aiming at improving the energy output and energy conversion efficiency of thermophotovoltaic systems, a micro-combustor with high and uniform outer wall temperature is desirable. Therefore, the micro-cylindrical combustor with a novel micro-spiral fin is proposed to improve the thermal performance. The effect of inlet velocities of premixed hydrogen/air, the critical design parameters of the spiral fin length (L) and the spiral fin pitch (W) on the thermal performance of the micro-cylindrical combustor are numerically investigated. Results show that micro-spiral fin is beneficial to improve the outer wall temperature value and uniformity, which can significantly increase the emitter power and energy conversion efficiency of micro-cylindrical combustor. However, the improvement of thermal performance is at the cost of higher pressure loss. Furthermore, compared with all the investigated geometrical models, the micro-cylindrical combustor with spiral fin length at the size of 14 mm and spiral fin pitch at the size of 2.355 mm obtains the best comprehensive heat transfer performance.