Development of a Pulsating Heat Pipe Test Apparatus and Investigation of Pulsating Heat Pipe Performance

Nick Hansen

Abstract

Pulsating heat pipes (PHPs) are passive, two-phase heat transfer devices. The working fluid within the PHP is driven by a saturation pressure difference in the working fluid caused by the temperature difference between the evaporator and condenser sections of the PHP. While many research projects have been undertaken in the past decade to investigate the physical mechanisms of PHP operation, numerous aspects require further study. In this work, a PHP test apparatus was designed with the versatility to operate under a wide range of many of the variables that affect PHP operation. The performance of the apparatus and instrumentation was validated by verification of PHP heat transfer performance trends found in previous research. Next, the effect of the direction of change of heat dissipation rate was explored by approaching a quasi-steady state by either increasing or reducing the evaporator temperature to a given heat input. It was found that an overlap existed between the two approaches; rather than having a single, steady-state operational evaporator temperature, there is a temperature range within which the evaporator will fluctuate for a given heat input and condenser temperature. Finally, the effect of condenser temperature on PHP performance was tested. It was found that, for water, an increase in condenser temperature improves performance. It is therefore possible, in some cases, to dissipate more heat for a given evaporator temperature by increasing the condenser temperature.