Thermoelectric devices tested for thermoelectric performance are usually heated at one end and cooled at the other, and a stable temperature difference is established between the two ends of the device. Then, the open circuit voltage voc, output power P and thermoelectric conversion efficiency when connected with different load resistors are measured. Then, the large output power pmax and large conversion efficiency max under the temperature difference are analyzed.
Existing thermoelectric performance test systems and measurement methods have the following shortcomings:
(1) The conversion efficiency of the thermoelectric device is determined by the heat flux qh flowing into the high temperature end of the thermoelectric device and the output power P of the thermoelectric device, and the calculation formula is =p/qh. The existing method calculates the heat flow qh by measuring the temperature difference between different locations of the heat source. This method requires additional calibration to measure the thermal conductivity of the heat source material, and it is difficult to accurately evaluate the heat loss caused by convective heat transfer and radiation heat transfer between the heat source and the environment, which will introduce errors and make the calculated thermoelectric conversion efficiency low.
(2) In order to obtain the large output power pmax and large conversion efficiency max of the thermoelectric device at a given temperature difference, it is necessary to measure the current and voltage flowing through the load under different load resistance, and the large output power pmax of the thermoelectric device and the corresponding large conversion efficiency max can be obtained by fitting and solving.
However, due to the Peltier effect, when the thermoelectric device outputs current, the hot end of the device absorbs heat, and the cold end releases heat, and with the increase of the output current, this effect will become more significant, resulting in the thermoelectric device hot end temperature decline, cold end temperature increase, thereby reducing the temperature difference between the two ends of the device. If measured directly, large output power pmax and large conversion efficiency max will be lower.
Therefore, the thermoelectric performance test system and test method can solve the problems of the existing thermoelectric device performance test system and test method are inaccurate and the measurement error is large.
The thermoelectric performance test includes a pressure bracket, heating block and cooling block installed in the bracket to heat the hot end of the thermoelectric device and cool the cold end of the thermoelectric device. The test system also includes a test circuit. The test circuit comprises an electronic load electrically connected with the output electrode of the thermoelectric device and capable of adjusting the resistance value instantaneously; The test circuit instantaneously adjusts the resistance value of the electronic load, and measures the output current value and voltage value of the thermoelectric device under different resistance values, so as to obtain the power generation performance parameters of the thermoelectric device. In addition, the test system includes insulation blocks; The heating block is embedded in the insulation block, and one side of the heating block is reserved for contact with the hot end of the thermoelectric device, so that the heat flow in the heating block flows into the thermoelectric device; During the test, the temperature setting of the insulation block matches the temperature of the heating block, and the heat loss on the surface of the heating block is eliminated. The test circuit is connected to the computer equipment.