Heat Pipe Bending Effect on Cooling Effectiveness in Electrical Machines

Heat pipes (HPs) are being extensively explored in motor cooling scenarios for enhanced cooling capacity. HPs are commonly bent to adapt to the compact structure of electrical machines, whereas the bending effect on motor cooling effectiveness still requires further investigation. This article analytically and experimentally studies the effect of the bending process, including bending angle and bending radius, on HP thermal properties. Cooling density is defined and derived to analyze the tradeoff between HP thermal performance and additional volume due to HP installation. Practical guidelines for feasible HP bending solutions under different space constraints are provided to achieve a higher cooling density. Finally, the HP bending effect on motor cooling effectiveness under various cooling methods is quantitatively evaluated through a validated thermal model based on a stator-winding assembly. The bending process can degrade the HP equivalent thermal conductivity by up to 76%, thus leading to a temperature difference of 4.8 K under liquid cooling conditions.

Automated summary

This article investigates the effect of bending on the thermal properties of heat pipes used in motor cooling, provides practical guidelines for bending solutions under different space constraints, and quantitatively evaluates the impact of bending on motor cooling effectiveness through a thermal model.