Performance Analysis And Thermal Reliability Test Of Thermoelectric Refrigerators Under Extreme Conditions

With the development of electronic components toward miniaturization,high frequency and integration,solving the heat dissipation problem has become the key to the stability and reliability of electronic components.Thermoelectric refrigerators have been widely studied and applied in the field of electronic device heat dissipation because of their small size,high temperature control accuracy,no moving parts and quick response.However,when applied in some special occasions,thermoelectric refrigerators are easy to be in extreme conditions,and the refrigeration performance as well as reliability of thermoelectric refrigerators is challenged.However,most researches on thermoelectric refrigerators currently focus on the room temperature,while the refrigeration effect of refrigerators under extreme conditions is not clear.Based on the above research background,the performance characteristics and thermal reliability of thermoelectric refrigerators under extreme conditions are studied.In this thesis,a multi-physical field coupling simulation model of thermoelectric refrigerators is established,and the accuracy of the model is verified based on the performance test platform of thermoelectric refrigerators.Secondly,using the simulation model of the thermoelectric refrigerator,the change rule of the refrigeration performance of the thermoelectric refrigerator under the conditions of extremely low temperature and extremely high temperature is studied,the causes of the performance change and the influence of physical parameters are analyzed,and the optimal operating current of the device under extreme conditions is determined.At the same time,the change rule of the temperature of the cold and hot ends under the maximum heat load is explored,and the influence of the working current and heat load on the refrigeration coefficient is analyzed.Then,the thermal reliability of the thermoelectric refrigerators under extreme conditions is tested by high temperature test,cold and heat shock test and power cycle test.Finally,the thermal stress distribution of thermoelectric refrigerators under the condition of maximum thermal load is researched,and the measures to improve the reliability of thermoelectric refrigerators are discussed.Research shows that at extremely low temperatures,the performance of the thermoelectric refrigerator decreases with the loss of the hot side temperature and When the temperature of the hot end is reduced to-60 ℃,the maximum cooling temperature difference and the maximum cooling capacity decrease by 51.7% and 40% respectively compared with the room temperature(the hot end temperature is 27℃);However,optimizing the physical parameters of thermoelectric materials at extremely low temperatures does not significantly improve the refrigeration performance of the device.Under the extremely high temperature condition,the refrigeration performance will increase first and then decrease with the increase of hot end temperature,and reach the best when the hot end temperature is150 ℃.At this time,the maximum refrigeration temperature difference and maximum refrigeration capacity are increased by 48.6% and 31.52% respectively;It is worth noting that the maximum cooling capacity can be greatly improved by optimizing the physical property parameters of thermoelectric materials under extremely high temperature conditions,and the maximum cooling temperature difference can be significantly improved when the hot end temperature is higher than 150 ℃.Under the condition of maximum thermal load,the effective COP of the thermoelectric refrigerator decreases obviously with the increase of thermal load or input current.When the thermal load increases from 1.5W to 2.3W,the maximum effective COP of the thermoelectric refrigerator decreases by 66.7%,while the optimal operating current decreases by 45.5% compared with that at room temperature.For the thermal reliability test,compared with high temperature test and thermal shock test,thermoelectric refrigerators is more likely to fail during power cycle test.The main reason for the failure of thermoelectric refrigerators is that the thermal stress of the copper joint and the Sn Sb solder layer is too large.The thermal stress can be reduced by using the materials with better thermal expansion coefficient and reducing the contact thermal resistance between different materials.The research content of this thesis has a certain reference value and guiding significance for the use and optimization of thermoelectric refrigerators under extreme conditions.