Cryogenic Pulsating Heat Pipes – Update and Direction

J.M. Pfotenhauer, F.K. Miller, C. Xu, X. Sun

University of Wisconsin - Madison

Cryogenic pulsating heat pipes (PHP) present a number of unique features as compared to their room temperature counterparts.  The pressure and temperature range defined by the two-phase regions for a number of the cryogens is easily accessible with standard experimental processes.  As a result, one can observe temperature dependent fill ratios, operation into the supercritical region, and specific-volume-dependent limiting behavior at high heat loads.  The viscosity for many of the cryogens is sufficiently low so that orientation effects are not reduced by increasing the number of turns.  Although no visualization studies have been reported due to the challenge associated with the low temperatures, numerical models and CFD studies are providing a description of the internal flow patterns and system level behavior.  This report provides an update on recent developments regarding cryogenic PHPs including details related to the associated modeling activities.