Validation of a High-Temperature Experimental Setup for Thermoelectric Characterization of Novel Materials

Abstract

This research validates an experimental setup to measure the thermal and electrical resistances of novel thermoelectric materials. The efficiency of these materials increases with temperature, with maximum values around 600 °C. New experimental setups that take account of the heat transfer losses and material properties at that high temperature are needed. The sample for this validation is a thermoelectric generator, TG12-8L from Marlow Industry. A low AC current (~5 mA) was applied to measure the electrical resistance, minimizing the Joule heating and Peltier effects. The thermal resistance was calculated by using a 1-D steady state model. For that model: 1) the setup was enclosed in a vacuum chamber to minimize the convection heat losses, while a ceramic heater was used as the heat source; 2) to improve the thermal contact with the sample, two thin aluminum plates sandwiched the sample and were used as a heat spreader; 3) A copper block with K-type thermocouples for heat flux measurements were used. Electrical resistance around 1.5 ohms for the sample was calculate from the voltage versus current graph, with excellent agreement with the manufacturer values. As expected, the electrical resistance was increasing with temperature. The thermal resistance was calculated as 1.503 °C/W, which is higher than the manufacturer values. This difference could be due to radiation heat transfer and other energy losses, and also due to the unsteady measurements in the big thermal mass in the setup. Future setups will minimize the heat transfer parasitic effects and time for steady state