Study On The Performance Degradation Of Thermoelectric Cooling Chips With Poor Heat Dissipation And Interface Contact Effects

There is an interface effect at the junction of metal conductor and thermoelectric material inside the thermoelectric cooling(TEC)chip,that is,boundary thermal resistances caused by material mismatch and contact effects caused by surface defects.In the case of poor heat dissipation,contact effect is particularly prominent,such as cracks caused by thermal stress.In this study,finite element method and commercial software ANSYS Workbench were used,and a TEC chip was taken as the research object to study the influence of several bad working conditions of the TEC chip on the cooling capacity of the TEC chip.For example,poor heat dissipation,thermal stress concentration,and increased contact effects.This article finally points out the possible failure mechanism of TEC chips,and provides a reference for engineering applications.The results of a study on a non-uniform temperature distribution show that as the excess temperature and the scale factor increase,the cooling capacity decreases,the power increases,thedecreases,and the peak thermal stress increases.Under the influence of the quantized non-uniform temperature field,the relative refrigerating capacity deviation reaches to-8.788%,the relative power deviation reaches to 2.608%,the relative coefficient of performance()reaches to-10.9%,and the maximum thermal stress reached 268 MPa.The contact deterioration caused by the concentration of thermal stress was expressed by the changes of N and M,which are the magnifying factors of thermal contact resistance and electrical contact resistance,respectively.Considering the non-uniform temperature distribution and contact effects at the same time,the research shows that the chip performance decline caused by local poor heat dissipation does not exceed 10%,and the chip performance decline caused by thermal contact resistance does not exceed 50%.However,the increase in electrical contact resistance has the most obvious impact on the performance of the chip.Whether it is_c mode ormode,the influence of M on the performance curve is far more than the other parameters.In severe cases(=400),the chip performance can be reduced by 100%,that is,the working ability is completely lost.The deterioration of the contact also leads to a drift of the optimal current.The phenomenon of stress concentration causing local material deformation,dislocation,and cracking is called stress warpage which appears as local contact deterioration,that is,changes in N and M.According to the calculation results,using the dimensionless cooling capacity as the index,the working area(0.9～1),transition area(0.3～0.9)and deterioration area(0～0.3)were defined.When the working state of the TEC chip is in the deterioration area(0～0.3),its cooling capacity drops below 30%,which can hardly meet the cooling demand,the TEC chip fails at this time.