Thermal Management of the High-power Electronics in High Temperature Downhole Environment

Abstract

The logging tool, which is utilized to detect the underground oil and gas resources, is a typical electronic instrument working in extremely high-temperature downhole environment (∼200°C) for more than 9 hours. Generally, the internal electronics can only withstand the temperature below 125°C, and thus adopting thermal management methods to ensure its normal operation turns into an urgent task. Previous researches mainly focused on the thermal management methods of the low-power electronics in the logging tool, but these methods were not suitable for high-power electronics due to a significant thermal resistance between the heat source and heat storage module. To solve this issue, a new thermal management method of integrating the heat sink and the heat storage module was proposed to enhance the heat transfer between electronics and heat storage module. The thermal performance of the structure was evaluated by the finite element method and the experiment. The simulated results show that the temperature of heat transfer and storage integrated structure is lower and more uniform than that of conventional finned heat dissipation structure, the maximum temperature of heat source drops from 165.8°C to 133.4°C, and the utilization rate of latent heat increases from 52.8% to 63.5%. Besides, inserting heat pipes to PCMs significantly reduces the maximum temperature to 110.7°C and increases the latent heat utilization rate to 99.0%. Further, the experimental results show that the electronics temperature can maintain below 125°C for 9 hours with the proposed thermal management method, which is consistent with the simulated results.