Investigation on effect of fin pattern of hot-side heat sink under expulsion flow for a portable thermoelectric unit

The compactness of the thermoelectric energy conversion system is mainly constrained by mechanical design of the heat sinks. Particularly, the hot side heat sink of a thermoelectric unit is critical in system performance due to the fact that a larger heat dissipation capacity of hot-side heat sink can endure larger Joule heating of a thermoelectric module. For the portable thermoelectric energy conversion unit, air-cooled heat sink is more practical to be used. However, the low heat transfer coefficient with air fluid makes the thermal resistance from fin to ambient dominant the overall heat sink performance. This work aims to better understanding of the effect of fin pattern on thermal and flow resistance of an air-cooled heat sink under expulsion flow and choose a more favorable fin design for a portable thermoelectric conversion unit. Numerical result shows that the stagger configuration outperforms inline configuration. Then comparison between square fin shape and hexagonal fin shape with both stagger configuration shows that the thermal resistance for different fin shape reaches to close value but by using hexagonal fin shape, the pressure drop can reduce by 22.5%. Thus, stagger hexagonal fin pattern is employed during the prototyping of the thermoelectric conversion unit.