A novel meso-scale combustion system for operation with liquid fuels

Abstract

A novel meso-scale combustion concept utilizing a flow-blurring injector to produce fine fuel droplets, a counter-flow heat exchanger to preheat reactants using product gas enthalpy, and porous inert medium to homogenize reactants and stabilize the flame is presented. The overall system is 30 mm long and 17 mm in diameter, with combustor diameter of 10 mm. For atmospheric pressure operation on kerosene fuel, the combustion system achieved heat release rate of up to 460 W, pertaining to energy density of 90 MW/m 3 based on the total volume and 230 MW/m 3 based on the combustor volume. The combustor performance was determined from surface temperatures measured by an infra-red camera, product gas temperature measured by an R-type thermocouple probe, and carbon monoxide (CO) and nitric oxide (NO x ) concentrations measured by a miniature sampling probe attached to gas analyzers. A comprehensive Computational Fluid Dynamics (CFD) model incorporating conjugate heat transfer, radiation heat exchange, flow and heat transfer in PIM, and heat release by combustion was developed and validated in this study. The CFD model accurately predicted the thermal performance of the combustion system. A 1D, burner-stabilized flame model incorporating detailed chemical kinetics was used to predict the flame structure. Model predictions are compared with measured CO and NO x concentrations, and subsequently, analyzed to identify the key reactions affecting the NO x production.