Electrohydrodynamically augmented micro heat pipes

For high power density dissipation, micro heat pipes and micro grooves have demonstrated much promise. Several experimental investigations were conducted to evaluate the potential benefits of electrohydrodynamic (EHD) forces on the operation of micro heat pipes. In these experiments, electric fields were used to orient and guide the flow of the dielectric liquid within the micro heat pipes from the condenser to the evaporator. The first series of experiments indicate that the heat transport capability of the EHD micro heat pipes is increased by up to 6 times of that of conventional ones. Simultaneously, a theoretical model was developed to predict the maximum heat transport capability for various electric field intensities and micro heat pipe geometries. The analytical model agrees well with the experimental results. The model shows that large pore sizes are optimal from a heat transport capacity perspective. Finally, a critical assessment of the experimental results suggest an alternative design capable of achieving as much as a 240 times improvement in the heat transport capacity in comparison to traditional micro heat pipes.; Another means to augment the heat transport capacity of micro heat pipes is to employ an ion-drag pumping. An analytical model is developed to evaluate the maximum heat transport capacity as a function of the applied electric field. The predictions indicate that ion drag pumping can achieve a four times increase in heat transport capacity under the application of an electric field relative to what would exist in the absence of a field. A transient analytical model was developed to permit variation of the electric field with applied thermal load. A proportional-integral-derivative controller was used to simulate active temperature control. The feasibility of achieving active temperature control was demonstrated experimentally.; Finally, a simpler EHD enhanced micro groove model was constructed and tested. A pair of electrodes was used as a liquid artery to convey the working liquid from the condenser to the evaporator. A six times increase of the heat transport capability was obtained.