Abstract— pulsating (or oscillating) heat pipes (PHP or OHP) are new two-phase heat transfer devices that rely on the oscillatory flow of liquid slug and vapor plug in a long miniature tube bent into many turns. The unique feature of PHPs, compared with conventional heat pipes, is that there is no wick structure to return the condensate to the heating section; thus, there is no counter current flow between the liquid and vapor. Significant experimental and theoretical efforts have been made related to PHPs in the last decade. While experimental studies have focused on either visualizing the flow pattern in PHPs or characterizing the heat transfer capability of PHPs, theoretical examinations attempt to analytically and numerically model the fluid dynamics and/ or heat transfer associated with the oscillating two-phase flow. The existing experimental and theoretical research, including important features and parameters are discussed. Progresses in flow visualization, heat transfer characteristics, and theoretical modeling are reviewed. Finally, unsolved issues on the mechanism of PHP operation, modeling, and application are discussed.

Index Terms— Pulsating heat pipe, Oscillating heat pipe

Cite: Prafull V Shahare and K K Jain, " Review of Unsolved Matter Related to Pulsating Heat Pipes," International Journal of Mechanical Engineering and Robotics Research, Vol. 1, No. 2, pp. 220-228, July 2012.