Cooling electronic components using electrohydrodynamically induced convection

The rapid growth of the development of electronic components makes them more and more powerful and smaller. Despite being very reliable components due to the absence of moving parts, its reliability and lifespan can be reduced owing to failures caused by overheating. Thus, new efficient cooling techniques should be studied to guarantee the correct operation and lifespan of this type of components. An electrohydrodynamic system is studied in the following Master Thesis based on the experiment of Moghanlou, F. S. et al. (2014): Experimental study on electrohydrodynamically induced heat transfer enhancement in a minichannel. A CFD analysis is performed in order to determine the effect of electric field on heat transfer enhancement and pressure drop for different Reynolds numbers for laminar flow through a square minichannel. The device is composed of three different parts: inlet, outlet and test section. The fluid passes through the inlet section in order to become hydrodynamically fully developed. The test section is composed of a copper wire located at the top simulating the high voltage electrode, and a heated plate located at the bottom as the electronic component to be cooled down. Besides, the bottom of the test section (the heated plate) is considered as ground. The walls of the minichannel are thermally and electrically insulated. The high voltage electrode injects charge through the fluid, producing a secondary flow towards the ground (heated plate). The neutral molecules of the fluid are pushed by this secondary flow, thus the velocity profile of the flow is modified. Some different numerical simulations with the ANSYS Fluent software are performed in order to study the electrohydrodynamic physics and determine the effects of the injection of charge in the flow. Some different parameters are studied with the purpose of analysing the heat transfer enhancement and the pressure drop and explain the behaviour of the electrodynamic device. By analysing the results, it can be concluded that the effects of the electric field increase when the Reynolds number decreases. In fact, for the scenarios with the lower Reynolds number, the modification of the fluid is more significant. A recirculation phenomenon is observed at the outlet of the test section. The electric field contributes negatively to the momentum equation at this part of the minichannel, reintroducing fluid towards the test section and no contributing to the heat transfer enhancement. An increase of pressure drop is observed with the appliance of the voltage and this augmentation rises with the voltage applied, and thus with the strength of the electric field. PEC values performed shows that the 2D configuration is efficient for scenarios with 5 kV and 10 kV applied at the wire. PEC values increase with the voltage. The recirculation problem becomes more noticeable when the voltage applied is greater and thus, with the strength of the electric field. Regarding the 3D model, none of the scenarios shows a PEC value greater than unity so the overall efficiency of the cooling technique studied is lower. However, by performing a segmented temperature analysis of the heated plate, the temperature increase due to the recirculation phenomenon is localised at the end part of the plate, and the maximum temperatures reached for the first part of the plate are lower. This temperature reduction is perfectly noticed in scenarios with the lower Reynolds number and less visible in the scenarios with the higher Reynolds number.