Experimental Study on a Hydrogen Closed Loop Pulsating Heat Pipe with Different Adiabatic Lengths.

Pulsating heat pipes (PHPs) are promising heat transfer devices due to their high heat transfer rate, simple construction, and low manufacturing cost. Most previous investigations focused mainly on their performances at room temperature. In order to have a better understanding on their thermal performances in the cryogenic field, a PHP element with liquid hydrogen as the working fluid has been fabricated. In this paper, the effect of adiabatic length (100 and 500 mm) on the thermal performance of the hydrogen PHP was investigated in order to determine whether it is capable of transferring heat over a long distance. Experiments were carried out at the filling ratio of 51% and the heat loads from 0 to 14 W. It can be observed that the two PHPs are able to maintain stable temperature profiles during the operation as the heat load increases. Their thermal resistances are almost constant around 0.3 K/W, but that of the longer PHP is about 30% larger. The results demonstrate the potential advantages of PHPs to effectively transport heat over a long distance. [ABSTRACT FROM AUTHOR]