The Maximum Power Operating Point for a Combustion-Driven Thermoelectric Converter With Heat Recirculation

Abstract

A model is developed for determining the ideal operating point, based on maximum power output, for a thermoelectric conversion (TEC) element coupled to a combustor. In the analysis, heat recirculation from the combustor exhaust is included. Results presented here are relevant to the operating characteristics of small, combustion-driven energy systems. The model is composed of a TEC element, a combustor, a counterflow heat exchanger, and a thermal shunt resistance to the surroundings. Including the shunt is necessary due to the increased importance of this effect in small-scale thermal systems. From this combination of components, an optimal combustor operating temperature is found giving maximum power output and efficiency. The model is used to determine ideal performance figures as a function of system parameters such as the effectiveness of heat regeneration, loss of heat by conduction, and the parameters describing the thermoelectric conversion element (the so-called ZT parameter). Although a high degree of idealization is employed, the results show the importance of heat recirculation and the significance of thermal losses on system operation.