Development And Experiment Of Apparatus For Testing Physical Properties And Performance Of Thermoelectric Devices

With the development of thermoelectric materials and the demand for applications,the application research of thermoelectricity has been rapidly developed in the past 20 years.The physical property parameter acquisition and performance characterization of thermoelectric devices is a key step in the research of thermoelectric applications.For the existing test apparatus,it is found that it can only test electrical physical parameters or have low accuracy of thermal parameters measurement.Therefore,this paper designs a set of apparatus that can simultaneously measure the electrical and thermal properties and performance parameters of thermoelectric generation and cooling devices with good repeatability and high precision.By reviewing the existing thermoelectric test methods,the U-I curve method and the DC transient method were used to design and build a thermoelectric device physical property and performance test apparatus,and the test procedures were developed.Two commercial thermoelectric generation devices TEG-199-1.4-1.6 and thermoelectric cooling device TEC1-12706 were selected for physical property and performance testing.The test accuracy of the apparatus was analyzed and the effects of temperature,clamping pressure,load resistance and working current on its physical properties and performance were studied.The relative standard deviations of internal resistance and Seebeck coefficient of thermoelectric generation and cooling devices are within 1%,and the relative standard deviations of heat transfer coefficient and ZT are within 3.5%and 2.5%,respectively.The measured value or derived value of each physical property parameter is close to the manufacturer data,and the apparatus has high measurement accuracy.Among the physical properties of the thermoelectric generation device,only the internal resistance R is greatly affected by the average temperature of the hot and cold end.And it increases linearly with the increase of the average temperature of the hot and cold end.Increasing the temperature difference between the hot and cold ends is the most effective way to improve the performance of the thermoelectric generation device.Increasing the clamping pressure can also improve the performance of the thermoelectric generation device,but the effect is small.Under the constant heat flow condition,the load resistance corresponding to the maximum output power and conversion efficiency of the thermoelectric generation device is not equal to the internal resistance value.When the maximum cooling capacity or the maximum cooling temperature difference of the thermoelectric cooling device meets the requirements for use,the operating current should be made as small as possible and the maximum current I_max should not be exceeded to obtain a higher COP.Under the condition of constant working current,increasing the hot end temperature is beneficial to improve the performance of the thermoelectric cooling device,and the clamping pressure has no effect on the maximum cooling temperature differenceΔT_max,the maximum cooling capacity Q_C,max and the maximum cooling coefficient COP_max.Finally,by measuring the physical properties or performance parameters of thermoelectric generation and cooling devices in the atmosphere,the influence of atmospheric environment on the measurement results is analyzed.It is found that the measurement in the atmospheric environment has a greater influence on the thermal parameters,but has no effect on the electrical parameters.Compared with the measurement results in the vacuum environment,the heat transfer coefficient of the thermoelectric generation device increased by 2.76%,and the heat transfer coefficient of the thermoelectric cooling device increased by 8.96%.