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.

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The thermal performance of a miniature, three-dimensional flat-plate oscillating heat pipe (3D FP-OHP) was experimentally investigated during high gravity loading with non-favorable 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 hyper-gravity loading up to 10g. Results show that at ten times the acceleration due to gravity (10g) 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.

The Pulsed Power Physics Branch at the U.S. Naval Research Laboratory (NRL) is developing a battery-powered, rep-rate charger for a 60-kJ capacitor bank. The goal is to charge a 4800μF capacitor to 5kV in five seconds for a fifty shot burst. A bank of LiFePO4 batteries is used with a full H-bridge converter and transformer to elevate the 500V battery voltage to a 5kV secondary voltage. The operation of the Integrated Gate Bipolar Transistor (IGBT) generates heat as a byproduct of the energy transfer from the batteries to the capacitor, which must be effectively removed. The traditional method of cooling the IGBTs involves a passive heat sink and forced air cooling, which can be quite large if the dissipated power load is high enough. This work investigates the replacement of the forced air cooling method with an oscillating heat pipe (OHP). The OHP investigated herein was made of aluminum with dimensions of 130.1 mm × 101.9 mm × 2.5 mm. The OHP channel dimension imbedded in the aluminum block is 1.0 mm by 1.0 mm. Utilizing high effective thermal conductivity, the integrated OHP has the potential to reduce the overall system volume and enable the design of a sealed converter package. Numerical analysis and experimental results demonstrate that the OHP can significantly increase the effective thermal conductivity and enable a fast time response of the pulsed power DC-DC converter. Comparison with the numerical analysis show that the heat transfer resistance occurring in the cooling block is the primary resistance for the investigated IGBT OHP cooling.

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