Effect of micro-pin-fin arrays on the heat transfer and combustion characteristics in the micro-combustor

Micro-combustor is an important component elements of the micro-thermophotovoltaic (MTPV) conversion device. The combustion stability is critical to improve its thermal performance, and thus three kinds of combustors are compared by computational fluid dynamics (CFD), which includes single - channel combustor, alternate permutation combustor and in-line combustor. The influences of micro-pin-fin arrays on the performance of the micro-combustor are discussed. Results indicate that the maximum surface temperature of combustor with fins is about 100 K higher than that without fins and the mean temperature and heat flux of in-linecombustor are always higher in magnitude than those of the alternate permutation combustor. Analysis in this paper reveals that comparing with single-channel combustor, the micro-combustor with fins greatly enhances the heat transfer process through the wall. There are low velocity zones in the tail of fins, which can gather the reactants and prolong the residence time which make the combustion more sufficient and improve the effect of stable combustion. Meanwhile, under calculated conditions, the influence of micro-pin-fin arrays on the combustion reaction is stronger as the flow rate increase. The fin array in micro-combustor does not only improve the wall temperature but also minimize the wall temperature difference along the axial direction. Moreover, when the inlet velocity is larger than 4 m/s, the hydrogen conversion ratios of micro-combustors with fins was not strengthened obviously with the further increase of inlet velocity. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.