The operational characteristics of a pulsating heat pipe (PHP) under different startup modes

Abstract

A pulsating heat pipe is a two-phase passive heat transportation device. It is a serpentine capillary tube which is partially charged with the working fluid. A PHP does not have any moving parts and does not require any additional power source to operate. Its simple structure, scalability, effectiveness, and low manufacturing cost have made the PHP an attractive option for thermal management of electronic devices. Two startup modes of the PHP, a soft or gradual startup, and a hard or sudden startup have been reported in the literature. These startup modes govern the behavior of a PHP during the startup period, and it is presently hypothesized that it further affects the PHP performance under its steady-state operation. This study focuses on understanding the operational characteristics of a PHP as a function of the mode of startup. Experimental investigations were conducted on a single loop PHP over a range of heat inputs, and an attempt has been made to gain insights into the mechanisms of different startup modes using CFD modeling.