Thermal Performance of a Mesoscale Heat Regenerating Combustor

Abstract

Heat regenerating principle is a common strategy employed in mesoscale combustors to overcome the issue of thermal quenching of the flame. The present paper discusses the thermal performance of a mesoscale combustor fabricated using a low thermal conductivity ceramic material. Propane and air were used as reactants in this investigation. Flames could be stabilized successfully inside this combustor for a wide range of equivalence ratios and residence times. Experimental investigation of the reactant preheating and product exhaust temperatures was performed using K-type thermocouples which were so installed to provide non-intrusive measurement of temperature. Sufficient preheating temperatures ensure steady combustion whereas high exhaust temperatures indicate good thermal efficiency of the combustor. The reactant preheating temperatures were observed to be in the range 700K-1000K. However, the combustor exhaust temperatures were considerably lower than the combustion temperatures which implied that the combustor suffered significant heat losses. Exhaust temperatures were observed to be in the range 500K-750K. For a constant fuel flow rate the exhaust temperature increased monotonously with decrease in equivalence ratio until the blow-off condition. This implies that the combustors maximum thermal efficiency occurs at its lean blow-off limit. For a given fuel flow rate, preheating of the reactant was highest for slightly fuel-rich condition. It decreased monotonously on either side of this condition.