Study On Porous Media Combustor For Micro-Thermal Photovoltaic Power Generation System

With the development of micro-mechanical system(MEMS),micro-thermal photovoltaic power generation system(MTPV)research and development has gradually become a hot topic.The MTPV system uses fossil fuel combustion directly to generate electricity through low-banded photovoltaic cells.Because the energy density of fossil fuels is much greater than that of conventional chemical fuel cells,the MTPV system has been considered to be the best choice for alternative chemical fuel cells.To improve the energy conversion efficiency of the MTPV system,we must increase the wall temperature of the micro-scale burner on the one hand,and on the other,we must increase the wall uniformity of the micro-scale burner.Therefore,to improve the micro-burner wall temperature and enhance the uniformity of wall temperature is the core of the current research.In this paper,the effect of porous media on the wall temperature was studied.In this paper,the micro-scale burners filled with porous media were studied by means of experimental and numerical simulation methods,and compared with the backward-facing step combustor without filling the porous media.Experiments and simulations show that the wall temperature of the micro-scale combustor with porous media is significantly improved compared with that of the backward-facing step combustor without adding the porous medium.When the methane flow rate is 0.100 L/min and 0.125 L/min,the average temperature of the outer wall surface of the micro-combustor increases 35.85 K and 62.88 K,respectively,and the peak temperature increases 48.15 K and 81.71 K,respectively.It was found that the tail filling method could obtain more uniform wall temperature.In addition,we studied the stable effect of porous media surface on flame,we found that there was a stable limit,and the stability limit had a great correlation with the oxygen concentration.Through experiments and simulations,we also found that the porosity,thermal conductivity and pore size of porous media have different effects on the outer wall temperature of micro-scale combustor.Porous media with larger porosity,smaller thermal conductivity and smaller pore size in the micro combustor can obtain higher wall peak temperature.The peak wall temperature is lower when the smaller porosity,larger thermal conductivity and larger pore size of the porous medium is filled in the micro combustor,but the uniformity is better.We explained this phenomenon from the theoretical calculation.These results provide a reference for the filling of porous media with micro-scale combustor.