Factors affecting the performance of thermoelectric cooler (Ⅰ)

The principle of thermoelectric cooler (TEC) is solid thermoelectric effect. Comparing with other cooling methods, TEC has obviously different cooling effect. This cooling method takes electrons as energy carrier, and because of no need of refrigerant, there is no environmental pollution problem. TEC has no moving parts besides fan, so it has simple structure, small noise, high reliability, long service lifetime and some other advantages. Most of TECs are made of N type and P type thermocouple arms, which are composed of multiple pairs of thermocouples.

Due to the presence of heat transfer temperature difference, weld resistance between cooling element, conductive metal, heat dissipation exchange and so on, the cooling performances of thermocouples can be affected a lot.

1.Additional heat transfer temperature difference

Additional heat transfer temperature difference has the largest influences on the performances of thermopiles. As electric installation heat conduction layer, brazing layer and conductive layer have their own thermal resistance, the cold side temperature is lower than the node temperature of thermocouples and the hot side temperature is higher than that. The actual cold and hot side temperature of thermocouples are: , , where,  and  respectively represent the cold side heat transfer temperature difference and the hot side heat transfer temperature difference. In the same working conditions, with the increase of  and  will reduce and  will increase. So cooling capacity, cooling coefficient and the maximum obtained temperature difference will decline quickly. The electric installation heat conduction layer is made of ceramic or plastic, which has low thermal conductivity and large thickness, so the temperature difference generated by electric installation heat conduction layer is large, about 92% of the total temperature difference.

Some other influence factors will be introduced in the next articles.
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