Implementation of Ethanol Heat Pipe at Cetiat

Abstract

CETIAT is a calibration laboratory accredited by COFRAC. The temperature generators are stirred calibration baths (from −80 °C up to +215 °C), dry blocks and furnaces (from −90 °C up to +1050 °C) and thermostatic chamber (from −30 °C up to +160 °C). The best calibration uncertainty is achieved in calibration bath, for Platinum Resistance Thermometers (PRTs), it is 0.03 °C. Nevertheless, the daily calibrations lead to an uncertainty about 0.06 °C for industrial RTD sensors. The CETIAT is working on the implementation of a Gas Controlled Heat Pipe (GCHP) temperature generator to replace the thermometric baths in order to increase productivity and in order to improve temperature stability in the working volume of the generator. Many studies [1, 2], explain the advantage of this method. For this purpose, the new system must have better thermal performance and produce the same temperature range than the stirred baths.Two years ago, the CETIAT characterized a water GCHP for industrial applications cover the temperature range from +30 °C up to +150 °C [3]. The results were in good agreement with the expectations and water GCHP could be used to calibration production. But, we need to extend the temperature range towards the low temperatures. This year, the CETIAT characterized a new type of ethanol’s heat pipe. We used the same heat pipe but this time we replaced water by ethanol. The possibilities of using ethanol, would allow generation of temperatures between −40 °C and 30 °C low temperature enclosure.This article presents the first results on the study of a low temperature heat pipe made at CETIAT. The results obtained during the metrological characterization, in terms of temperature homogeneity and stability, in this study are encouraging. However, an issue with the stability of the cooling system diminish the quality of the results. The stability of the surrounding environment must be improved. This will be the subject of a future study. The results at 20 °C are very positive. Over an axial length of 250 mm, the thermal homogeneity is less than 5 mK.