Thermal performance of pulsating heat pipes with different heating patterns

• Non-uniform heating patterns could shorten the start time.
• The thermal resistance will be increased when non-uniform heating patterns is applied.
• It is better to take non-uniform heating patterns for start, take uniform heating patterns for stable operation.

The start-up and the heat transfer performance of pulsating heat pipes (PHPs) operated with various heating patterns are numerically studied at 30%, 50%, 70% filling ratio, respectively. The volume of fluid (VOF) method and continuous surface force method (CSF) are introduced to model the unsteady vapor–liquid two-phase flow. The results reveal that the PHPs at a lower filling ratio can start easily in the considered range. Furthermore, the heating patterns have a significant effect on the start-up process and thermal resistance of PHPs. Compared with the uniform heating pattern, non-uniform heating pattern can reduce the start-up period and increase the thermal resistance of PHPs.