Effect of large redundant volume on the performance of multiple turns helium pulsating heat pipe

Abstract

The quench process in high-field superconducting magnets releases a significant amount of energy, leading to a rapid increase in local temperature. This temperature rise can result in damage to the magnet components and even lead to magnet burnout. Therefore, it is crucial to effectively dissipate heat after a quench event occurs. Helium pulsating heat pipes (PHPs), as a novel and highly efficient heat transfer element, have been investigated for cooling superconducting magnets. However, during a quench event, the internal pressure of the helium PHP increases rapidly due to the sharp temperature rise, which can potentially cause pressure overload and damage to the PHP itself. Additionally, higher filling ratios exacerbate the pressure rise. One potential solution to address this issue is connecting a buffer tank to the PHP to reduce the pressure. However, this approach introduces a larger redundant volume, consequently diminishing the heat transfer performance of the helium PHP. This study focuses on mitigating such degradation through adjustments in structural design and optimization of operating parameters, particularly the filling ratio. By employing three different configurations of the PHP, the study investigates the coupling effect between structure and redundant volume on the performance of the helium PHP. The results indicate that, except for the series–parallel PHP with a filling ratio of 94.2 %, connecting the PHP to a buffer tank weakens the heat transfer performance in other configurations. Analysis of the series–parallel configuration 24-turn helium PHP reveals that the migration of helium gas among sub-PHPs facilitates pulsating motion, thereby alleviating the detrimental effects of the large redundant volume. Overall, this research examines methods to mitigate the heat transfer performance degradation caused by the introduction of a buffer tank and larger redundant volume in helium PHPs. The findings underscore the importance of considering the structural design and operating parameters to optimize the cooling efficiency of superconducting magnets.