Concept and combustion characteristics of the high-luminescence flame for thermophotovoltaic systems

The thermophotovoltaic (TPV) power system mainly consists of a heat source, an emitter and a photovoltaic (PV) cell array. One of the major deficiencies leading to the relatively low overall efficiency of the TPV power system is the spectral mismatch between the emitter radiation and the quantum efficiency peak of the PV cells. Therefore, application of high-luminescent-flame in the visible range is a cost-effective method to enhance the radiant efficiency of a small TPV system. The concept of the high-luminescent-flame combustor is proposed with central-porous liquid fuel-film injection of n-heptane and trace amount of iron pentacarbonyl, and an emitter tube. The metal-porous fuel-film injection is an effective method to increase contact surface and thermal conduction for liquid fuel vaporization and for flame stabilization. Chemiluminescence measurement and Abel deconvolution are further performed to identify the flame structure in two different porous materials, bronze and stainless steel, respectively. Flame structure and stabilization mechanism in the chamber can be related to the tribrachial flame. The radiant intensity of the iron pentacarbonyl flame is significantly enhanced by fivefold, and flame color turns to sliver-white. Inserting an emitter tube in the combustor can further effectively integrate the radiation from the flame luminosity and emitter incandescence, and improve the radiant efficiency of the TPV system.