Experimental investigation of the thermal resistance of advanced two-phase thermosyphon heatsinks

In this study, the heater-to-air thermal resistance of an air-cooled reflux thermosyphon with internal pool boiling and confined condensation was studied relative to four parameters the heater input power, the fan input power, the integrated heat spreader area and the condenser volume. Four different prototypes were identically designed except for their integrated heat spreader area and condenser volume. The prototypes were tested for a heater input power ranging from 200 W to 500 W and a fan input power from 2.5 W to 18 W. Each prototype was filled at its optimal filling ratio with a dielectric liquid that was degassed before the measurements. The heater-to-air thermal resistance of the prototypes was broken down into three intermediate thermal resistances: the heater-toliquid, liquid-to-condenser and condenser-to-air thermal resistances A model was constructed to predict each intermediate thermal resistance. The parameters of this model were fitted to the experimental data, to achieve a mean relative deviation and a maximum relative deviation of 3.4 % and 10 % respectively when comparing the model to the experimental data.