EXPERIMENTAL INVESTIGATION OF A SINGLE CLOSED LOOP PULSATING HEAT PIPE
Electronic devices are shrinking in size while their performance is increasing. The increased functionality has resulted in higher heat loads whereas the reduced sizes have complicated the thermal management further by making the heat fluxes more severe. Hence commercially competitive and efficient thermal management techniques have gained large significance in the electronics industry.
The pulsating heat pipes (PHPs) have been researched due to their promise as effective heat transport devices. The PHPs being less complicated in their construction render themselves as more than suitable alternatives to the conventional heat pipes. Though PHPs have the perceived advantages, reliable data for their simulation, design and performance prediction has not been established [1-2]. In this work, a single closed loop PHP has been experimentally studied to ascertain the performance and operating characteristics.
A PHP with a single loop of 2.5 mm internal diameter and 190mm overall length was tested for evaporator down orientation for varying heat loads. The fill ratio maintained was around 50% by volume with methanol as the working fluid.
The overall steady state thermal resistance (Rth) was estimated from the experiment for various input heat loads up to 70 W. The start-up characteristic for each heat load was recorded as a temperature trace with respect to time. The thermal resistance of the heat pipe was found to reduce with increasing heat loads with 70 W having a resistance of 0.46 K/W and an evaporator temperature of 110°C. The start-up was almost instantaneous for the higher heat loads whereas the PHP barely initiated operation at 10 W.