Although thermoelectric cooling technology has been developed very fast, there are still many problems that need resolution. Because of the material constraints, the cooling capacity of thermoelectric cooler (TEC) is limited and its cooling efficiency is too low. With the increase of the required temperature difference, the more the TEC series is, the lower the cooling efficiency is. So TEC cannot completely replace the traditional cooling technology, which can only be used in the small cooling capacity field. Only if the cooling capacity is improved, TEC can get more extensive application. The key is that better materials should be developed based on the cooling principle of TEC.
When the direct current I is through couple, the cooling capacity of couples should be the difference value of Piltier’s cooling capacity, Joule heat on the cold end and the heat of couple on the hot end.
When couple is working, the total power consumption is the summation of the resistance consumption and the consumption of overwhelming the thermoelectric potential:
So the cooling coefficient is
If the corresponding thermal coefficients λ, thermal conductivity σ, and thermoelectric coefficient α of couple arm are equal, the maximum temperature difference between the hot end and the cold end can be expressed as:
Obviously, the maximum temperature difference of TEC depends on the cold end temperature Tc and the figure of merit:
So in order to improve the thermoelectric properties of TEC, the figure of merit Z can be improved from considering three aspects, increasing thermal coefficients λ and thermal conductivity σ and reducing thermoelectric coefficientα.
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