Design Optimization of Plate-Fin Heat Sink with Forced Convection for Single-Module Thermoelectric Generator

Thermoelectric generators (TEGs) often use plate-fin heat sinks as cold side heat exchangers. In forced convection cooling, the net electrical power supplied by the TEG corresponds to generation (Seebeck effect) minus self-consumption (cooling fan power). Both effects have different trends as a function of the forced flow speed, so a maximum of the net electrical output power is expected at intermediate cooling air flow values. Here, a methodology to obtain 1) the forced flow speed value that maximizes the net electrical power for a given plate-fin heat sink geometry, and 2) the heat sink design (fin thickness and fin-to-fin distance) that optimizes the net electrical power for a fixed hot source temperature is proposed. The procedure is based on the development of a numerical model whose predictions are successfully validated with experimental data. Numerical results indicate that the optimal dimensions of the plate-fin heat sink depend, among others, on the TEG effective properties. For a given TEG, the net output power is less sensitive to changes in fin thickness than in fin spacing. For the cases here studied, the optimal heat sink designs have fin thickness of 0.32 and 0.44 mm with fin-to-fin distances of 1 mm.