Flame and heat transfer characteristics of a micro combustor with multihole baffle-induced inflows for a thermo-photovoltaic application

Abstract

For an effective thermo-photovoltaic application, the inflow effects on the flame and heat transfer characteristics of micro power generators are numerically investigated in a multihole baffled micro combustor. The flow inside the baffle hole is considered as a circular pipe flow. Various inlet profiles of the micro combustor are obtained by varying the baffle thickness corresponding to the length of the baffle hole. The velocity distribution of the flow past the baffle plate attains an M-shaped (also called saddle-back), a parabolic, or a fully developed profile according to the baffle thickness. For a baffle thickness less than the fuel hole diameter, the inflow of the combustion chamber has an M-shaped velocity profile with two off-center peaks. Vortical motions and lobe-shaped flame are promoted by this type of inlet condition. Combustion characteristics, including flame length, combustion efficiency, heat loss ratio, and preheating effect, are comprehensively examined to evaluate the possibility as an thermo-photovoltaic device. The results indicate that a micro combustor with a thin baffle (b_t ≤ 0.1D_f) increases the combustion efficiency and wall heat flux. This suggests that the current baffled combustor can be effectively applied in both micro power generation systems and micro thermal emitters.

Keywords:

• Baffle thickness
• flow recirculation
• lobed shape flame
• multihole baffled micro combustor
• secondary flows
• streamwise vortices
• thermal efficiency

Additional information

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B02012446, 2020R1A6A3A01097105).