Analysis of improved pulsating heat pipe designs for hot spot applications

Pulsating heat pipes (PHPs) are increasingly used for the thermal management of hot spots. A major goal in the design process of PHPs is the handling of high heat fluxes and, thus, improved thermal resistance. The thermal resistance can be reduced by increasing the latent or convective heat transfer. Two design approaches with that goal are presented in this study: a flower-shaped PHP design to increase the latent heat transfer and a star-shaped PHP design to increase the convective heat transfer. We compare the proposed designs to a state-of-the-art, meander-shaped PHP design. Thereby, we quantify the thermal performance and the flow pattern of the different PHP designs. The copper PHPs were filled with acetone and tested horizontally and vertically. The filling ratios varied from 0 % to 90 % and the heat inputs increased from 50 W to 200 W. Our results illustrate that the flower-shaped PHP design reduces the thermal resistance by 7 % in horizontal and 12 % in vertical position. We found a strong interrelation between flow pattern and heat transfer in PHPs. Our study shows that phase change plays a key role for the thermal resistance. Based on that, we provide design criteria to optimize the thermal capabilities of PHPs with a special focus on hot spots.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study compares different designs of pulsating heat pipes (PHPs), including flower-shaped and star-shaped designs, with the existing meander-shaped design. The results show that the flower-shaped design reduces thermal resistance and phase change plays a key role in thermal resistance. The study provides design criteria to optimize the thermal performance of PHPs.