Experimental investigation of oscillating heat pipes under direct current and pulse width modulation heating input conditions

An experiment was designed to quantify any change in thermal performance of an oscillating heat pipe (OHP) subjected to Pulse Width Modulation (PWM) power input as opposed to the more traditional Direct Current (DC) power input/heating. Two identical ThermAvant Technologies aluminum 152.4 × 50.8 × 2.0 mm3, 34 turn closed-loop OHPs with 0.76 mm diameter channels were built. One OHP was filled with acetone (54% by volume at room temperature) and another filled with R-134a (55% by volume at room temperature). The OHPs were tested horizontally with DC and PWM (at 2.88 Hz) heat inputs of 0-40 W. Three trials of each OHP and power type were performed. It was found that nearly all trials of each OHP were within one standard deviation of one another. Based on these results and prior findings in OHP performance repeatability it is reasonable to conclude that the use of PWM power input does not influence the thermal performance of a flat-plate OHP of this design.