Numerical Study on the Thermal Stress and its Formation Mechanism of a Thermoelectric Device

The strong thermo-mechanical stress is one of the most critical failure mechanisms that affect the durability of thermoelectric devices. In this study, numerical simulations on the formation mechanism of the maximum thermal stress inside the thermoelectric device have been performed by using finite element method. The influences of the material properties and the thermal radiation on the thermal stress have been examined. The results indicate that the maximum thermal stress was located at the contact position between the two materials and occurred due to differential thermal expansions and displacement constraints of the materials. The difference in the calculated thermal stress value between the constant and the variable material properties was between 3% and 4%. At a heat flux of 1 W·cm^(-2) and an emissivity of 0.5, the influence of the radiation heat transfer on the thermal stress was only about 5%; however, when the heat flux was 20 W·cm^(-2) and the emissivity was 0.7, the influence of the radiation heat transfer was more than 30%.

A Model to Evaluate the Device-Level Performance of Thermoelectric Cooler with Thomson Effect Considered

In this paper,a one-dimensional thermodynamic model was developed to evaluate the device-level performance of thermoelectric cooler(TEC)with the Thomson effect,contact resistance,gap heat leakage,heat sink,and heat load taken into account.The model was generalized and simplified by introducing dimensionless parameters.Experimental measurements showed good agreement with analytical results.The parametric analysis indicated that the influence of the Thomson effect on cooling capacity continued to expand with increasing current,while the effect on COP hardly changed with current.Low thermal contact resistance was beneficial to obtain lower hot-junction temperature,which can even reduce 2 K compared with the electrical contact resistance in the case study.The gap heat leakage was a negative factor affecting the cooling performance.When the thermal resistance of the heat sink was small,the negative effect of heat leakage on performance would be further enlarged.The enhancement of heat load temperature would increase the cooling power of the TEC.For example,an increase of 5 K in heat load can increase the cooling capacity by about 4%.However,once the current exceeded the optimum value,the raising effect on the cooling power would be weakened.The research can provide an analytical approach for the designer to perform trade studies to optimize the TEC system.

A Strategy to Reduce the Peak Temperature of the Chip Working under Dynamic Power Using the Transient Cooling Effect of the Thin-Film Thermoelectric Cooler

The thin-film thermoelectric cooler(TEC)is a promising solid-state heat pump that can remove the high local heat flux of chips utilizing the Peltier effect.When an electric current pulse is applied to the thin-film TEC,the TEC can achieve an instantaneous lower temperature compared to that created by a steady current.In this paper,we developed a novel strategy to reduce the peak temperature of the chip working under dynamic power,thus making the semiconductor chip operate reliably and efficiently.A three-dimensional numerical model was built to study the transient cooling performance of the thin-film TEC on chips.The effects of parameters,such as the current pulse,the heat flux,the thermoelement length,the number of thermoelements,and the contact resistance on the performance of the thin-film TEC,were investigated.The results showed that when a current pulse of 0.6 A was applied to the thin-film TEC before the peak power of the chip,the peak temperature of the chip was reduced by more than 10℃,making the thin-film thermoelectric cooler a promising technology for the temperature control of modern chips with high peak powers.