The thermal performance of a miniature, three-dimensional flat-plate oscillating heat pipe (3D FP-OHP) was experimentally investigated during high-gravity loading with nonfavorable evaporator positioning. The heat pipe had dimensions of 3.0 × 3.0 × 0.254 cm3 and utilized a novel design concept incorporating a two-layer channel arrangement. The device was charged with acetone and tested at a heat input of 95 W within a spin-table centrifuge. It was found that the heat pipe operated and performed near-independent of the investigated hypergravity loading up to 10 g. Results show that at ten times the acceleration due to gravity (10 g), the effective thermal conductivity was almost constant and even slightly increased which is very different from a conventional heat pipe. The gravity-independent heat transfer performance provides a unique feature of OHPs.

An experimental investigation of a compact, triple-layer oscillating heat pipe (OHP) has been conducted to determine the channel layer effect on the heat transport capability in an OHP. The OHP has dimensions 13 mm thick, 229 mm long, and 76 mm wide embedded with two-independent closed loops forming three layers of channels. The unique design of the investigated OHP can be readily used to explore the channel layering effect on the heat transport capability in the OHP. The experimental results show that the addition of channel layers can increase the total power and at the same time, it can increase the effective thermal conductivity of the OHP. When the OHP switches from one layer of channels to two layers of channels, the highest effective thermal conductivity can be increased from 5760 W/mK to 26,560W/mK. At the same time, the dryout limit can be increased. With three layers of channels, the OHP investigated herein can transport a power up to 8kW with a heat flux level of 103 Wlcrr? achieving an effective thermal conductivity of 33,170 WImK.

The effect of heat conduction through the adiabatic section on the oscillating motion and heat transfer performance in an oscillating heat pipe (OHP) was investigated experimentally. Two, closed loop, 6-turn OHPs were constructed; one with a separate copper block for the evaporator and condenser sections (split block design) and one using a single continuous copper block for the evaporator, adiabatic, and condenser sections (continuous block design). The results show that the presence of heat conduction directly from the evaporator wall to the adiabatic section and from the adiabatic section to the condenser of a heat pipe will reduce the oscillating amplitude of the evaporator, adiabatic, and condenser temperatures. It was also found that in addition to a higher level of temperature uniformity, the continuous block design results in better heat transfer performance than a heat pipe without conduction through the adiabatic section.

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A novel oscillating heat pipe (OHP) has been constructed and experimentally investigated featuring a meandering channel formed entirely by a wicking structure. The hybrid approach utilizes the wicking structure found in traditional heat pipes, while also utilizing the meandering channels and plug flow of OHPs. Water and acetone were both tested with acetone demonstrating higher peak performance and water demonstrating a wider operating range. While OHPs typically require a high startup power, the hybrid approach presented achieves startup at very low power input and demonstrates a significant improvement in performance over the same device without any working fluid.