Pulsating heat pipes filled with acetone and water under radial rotation conditions: Heat transfer performance and semi-empirical correlation

Abstract

A significant amount of heat can be generated during the operation of rotary machinery, which degrades its working performance and lifetime. It has been proven that, under radial rotation conditions, pulsating heat pipes (PHPs) can operate with good thermal performance. PHPs have excellent potential for application in rotary machinery, owing to their enhanced heat transfer and material duration. Experimental studies on radially rotating PHPs remain scarce, and further in-depth physical understanding is required to achieve a better thermal design for practical configurations. In this study, the effects of centrifugal acceleration and heat flux on the heat transport in radially rotating PHPs were investigated in detail. The results demonstrate that centrifugal acceleration can promote the circular motion of chains of liquid plugs and vapor slugs with an improvement in thermal performance, particularly above a given heat flux threshold and a critical value of the rotation velocity. In addition, by considering the key influencing parameters, a semi-empirical correlation of dimensionless numbers was built to estimate the heat transport. Additionally, dimensionless numbers, i.e., Weber number, temperature number (ΔT/Tev), and a newly-defined number (Ψ1, represents the influence of heat flux, surface tension and centrifugal acceleration), significantly impact the thermal performance.