Thermoelectric device to measure the thermal conductivity of materials

A new device for the measure of the thermal conductivity has been developed. This device is very fast in taking measurements and does not need to reach the steady state to do. Therefore, it will be ideal for the quality control of thermal isolating materials. Right now, it is being built to be able to test samples of different dimensions, ranging from 600*600 to 300*300 mm and thickness within 20 and 250 mm. The measures are taken in less than 30 minutes. Device configuration: it consists of two plates each of them with 14 peltier pellets. Five of the 14 pellets work as Seebeck effect, that is to say, they measure the heat fluxes coming in and out the device. The other nine pellets work to reach an inside temperature, controlled by a 0.1°C precision PID, of 25°C up or below ambient temperature. The sample is sandwiched between the two plates which provide a temperature distribution and heat flux in each side of the sample. This information is then sent to a computer which compares this information (temperature and heat flux) to that given by the numerical model previously defined. The computer continuously modifies both the thermal resistance and capacity of the sample according to the information coming from the device in order to meet it. All the measures and calculus are automatically made and saved by the system. The thermal inertia of the device is also considered in the numerical model so as to get more precise measurements during the transitory state. This system requires a calibration once. In this paper this technique will be discussed and some results plotted.