A hybrid thermal management system combining liquid cooling and phase change material for downhole electronics

The electronics inside the logging tools are prone to failure due to the extreme thermal environments. In this study, a hybrid thermal management system using liquid cooling and phase change material (PCM) for downhole electronics is proposed to extend the workable time. In this system, a spiral pipe and a S-shaped pipe are respectively arranged inside the PCM and the cold plates to strengthen the heat exchange. To investigate the performance of this system, the transient flow and heat transfer simulation are implemented using finite element method. The accuracy is validated by comparing with the reported experimental results, showing an error of less than 6.7 %. The results show that the hybrid thermal management system increases the operating time of the electronics from 230 min to 450 min, which is attributed to the introduction of liquid cooling. The maximum temperature difference between the electronics and PCM reduces from 30 °C to 2 °C. Moreover, the effect of flow rate, spiral pipe spacing, heating power and ambient temperature on the temperature control performance are explored. This work provides a guidance for the design and optimization of logging tools, which is significative to shorten their research and development cycle.