Study on heat transfer coupling mechanism of direct thermoelectric conversion with regenerative cooling for supersonic combustor applications

Direct thermoelectric conversion is a promising technology that converts aerodynamic and combustion heat into electric energy for thermal management of supersonic combustors. However, the heat transfer process of direct thermoelectric conversion coupled with regenerative cooling of supersonic combustors is rarely studied and the coupling mechanism is not clear. In this paper, a novel "SANDWICH" thermoelectric/cooling integrated model (TCIM) proposed by the present work based on Skutterudite (SKD) or Half-Heusler (HH) thermoelectric conversion devices is analytically studied. The energy conversion and heat transfer mechanism of the direct thermoelectric conversion coupled with regenerative cooling are revealed. Using the analytical model, the effects of structural parameters of thermoelectric conversion device and the heat transfer coefficient of regenerative cooling on the energy conversion efficiency and output power are investigated for two typical thermal conditions corresponding to the isolation part and the combustion part of a Mach 2.5 supersonic combustor. The analytical results showed that larger size of the thermoelectric conversion device can effectively improve the conversion efficiency and output power per unit area. Increasing the heat transfer coefficient of regenerative cooling can lower the structural temperature and increase the output power per unit area by more than 12%. Furthermore, with a multi-parameter optimization method based on Genetic Algorithm, optimization for the output power per unit area is conducted with variations of the structural parameters of TCIM under constraints of the tolerance temperature and the types of thermoelectric conversion devices. A more than 10% increase in the output power per unit area for both SKD and HH TCIMs are achieved via the optimization.