Experimental investigation of the thermo-hydraulic performance of a stacked flat plate oscillating heat pipe

A stacked double-layer flat plate oscillating heat pipe charged with degassed DI water was designed, fabricated, and characterized under different operating conditions (orientation, cooling water or system temperature and heat load). The oscillating heat pipe was designed to dissipate 500 W within a footprint of 170 mm x 100 mm. The oscillating heat pipe had a total of 46 channels (23 channels per layer) with a hydraulic diameter of 2 mm. Tests were performed to characterize the performance of the oscillating heat pipe for axial heat transfer. The stacked oscillating heat pipe showed a distinctive feature in that it overcame the absence of the gravity effect when operated in a horizontal orientation. The thermal performance was found to be greatly dependent on the operational parameters. The oscillating heat pipe was able to dissipate a heat load greater than 500 W without any indication of dry-out. An increase in the cooling water temperature enhanced the performance and was accompanied with an increase in the on/off oscillation ratio. The lowest thermal resistance of 0.06 K/W was achieved at 500 W with a 50 °C cooling water temperature, with a corresponding evaporator heat transfer coefficient of 0.78 W/cm2K.