| Nowadays,microelectronic chips are at the nanometer scale,but the thermoelectric leg used to cool the chips stay at the millimeter scale,which is far behind the technological level of electronic chips.When the working conditions and materials of the refrigeration unit are determined,the cooling capacity Q0 only depends on the ratio of the length L and the cross-sectional area S of the thermoelectric leg.If the cross-sectional area S of the thermoelectric leg is to be greatly reduced without affecting the cooling effect,the length L must be reduced in the same proportion.However,reducing the length of the thermoelectric leg will cause the distance between the hot and cold ends of the thermopile to be too close,resulting in a large amount of internal heat transfer,which greatly reduces the efficiency of the thermopile.If this problem can be avoided by optimizing the thermopile structure,it is expected to obtain ultra-high integration thermopile,which can greatly improve its heat flux and work efficiency.In this paper,an intermediate conductor were added to the thermoelectric legs of the thermopile with the traditional structure to form a structure in which the hot and cold ends are separated.Based on the thermoelectric module of COMSOL multiphysics,the thermopile with different materials and lengths of intermediate conductors was studied.In this paper,the influence of different materials and lengths of intermediate conductor on the temperature of hot and cold end of thermopile was analyzed.The temperature field of intermediate conductor with different length under different operating conditions was compared.Furthermore,the influence of different length of intermediate conductor on the temperature of thermoelectric leg was analyzed.The effect of the aspect ratio of the thermoelectric leg on the temperature of the hot and cold ends of the thermopile with a copper structure was also studied.Numerical simulation laid the foundation for the selection of thermopile in the experiment.In the experiment,many kinds of copper thermopiles with different sizes were fabricated by using the method of diaphragm thermopile.The temperature data and infrared thermal image of the hot and cold ends of the traditional thermopile and the copper structure thermopile were recorded using the temperature acquisition system,and the model and simulation results were verified.And the advantages of copper structure thermopile compared with traditional structure thermopile were analyzed.Research results show that the cold end temperature of copper thermopile was lower than that of aluminum thermopile under the same conditions.With the longer the intermediate conductor,the temperature of the cold and hot ends of the thermopile was lower.The effect of changing the length of the intermediate conductor on the thermal leg at the hot end was greater than the cold.In a certain range,with the increased of l/S ratio of thermoelectric leg,the cold end temperature of thermopile was lower,and the hot was higher.When the input current was greater than 1.5A,the cold end temperature of the thermopile with the aspect ratio of 2,2.5 and 3 increased sharply.In the design of thermopile,we should not blindly pursue the thermoelectric leg with large aspect ratio and long intermediate conductor.We would choose the appropriate size of intermediate conductor and thermoelectric leg according to the needs of actual refrigeration situation.There were some errors between the experimental values and the simulated values,but the overall trend was consistent.The experimental results verified the correctness of the model and simulation results.Finally,it was found that when the input current was 2A,the maximum temperature difference between the hot and cold ends of the copper thermopile was up to 90℃.In this paper,the temperature field of the copper structure thermopile was studied by combining experiment and numerical simulation.The new structure of hot and cold end separation opens a new exploration of thermopile.Expanding the application field of thermoelectric refrigeration technology can promote the energy conservation and environmental protection. |
