An experimental study towards the practical application of closed-loop flat-plate pulsating heat pipes

The thermal performance of a flat-plate closed-loop pulsating heat pipe (PHP) is experimentally obtained. The PHP is manufactured by means of CNC-milling and vacuum brazing of a stainless steel 316L bottom plate and lid. Each channel of the PHP has a 2∗2 mm2 square cross section. In total 12 channels (6 turns) fit in the 50∗200 mm2 effective area of the PHP. During the experimental investigation, the power input is increased from 20W to 100W through a 50∗50 mm2 evaporator section, while cooling is performed through a 50∗50 mm2 condenser section with the use of a Thermo-Electric Cooler (TEC). The PHP is charged with methanol with 40% filling ratio. The thermal resistance is obtained for different inclination angles. It is observed that the 6-turn device operates well in vertical orientation. It however does not operate horizontally. Moreover, experiments have shown that the operating orientation is between 15–30°. The overall thermal resistance was determined at 0.48 K/W for a 100 Wpower input in the vertical evaporator-down orientation.