Downhole Electronics Cooling Using a Thermoelectric Device and Heat Exchanger Arrangement

Abstract

This paper investigates the use of thermoelectric (TE) devices for thermal management of downhole electronics. The research carried out will help in the mitigation of costs associated with thermal damage of downhole electronics used in oil drilling industry. An experimental set up was prepared where a TE device was used in conjunction with heat exchanger and a cold plate to remove heat from electronics module. A finned copper rod in contact with hot side of TE device was used to reject the heat out to the ambient. The experimental set up was housed inside a cylindrical vacuum flask, which was in turn placed inside an oven to simulate thermally harsh downhole conditions. Experiments were carried out with electronics heat dissipation of 0–8 W and ambient temperature of 140 °C. Due to the differences in the environmental conditions of the laboratory and the practical downhole scenario, the experiment could not completely capture the conditions of downhole heat rejection. A mathematical model of the experimental apparatus was prepared and validated against the experimental results. The model was used to predict performance of a TE device for thermal management of downhole electronics at an ambient temperature of 200–250 °C. It was observed that the ability of the thermal management system to keep electronics cool varied from 30 °C to a few degrees below the surrounding temperature, for chip wattage varying from 0 W to 8 W, respectively.