EXPERIMENTAL AND COMPUTATIONAL ANALYSIS OF AN ELECTROHYDRODYNAMIC MESOPUMP FOR SPOT COOLING APPLICATIONS

Abstract

As electronic products become faster, more compact, and incorporate greater functionality, their thermal management becomes increasingly more challenging as well. In fact, shrinking system sizes, along with increasing circuit density, are resulting in rapid growth of volumetric heat generation rate and reduction in surface area for adequate heat dissipation. Moreover, system miniaturization by employing microfabrication technology has had a great influence on thermal and fluid research Smaller systems have many attractive characteristics and can be more conveniently fabricated using batch production technologies. One of the fields showing promising potential in microsystems and electronics cooling is the use of the phenomenon of electrohydrodynamics or EHD defined as a direct interaction between the electric and hydrodynamic fields where the electric field introduces fluid motion. The objectives of the present study were to identify the physics of these phenomena as related to the present study, to simulate it numerically, and to verify the modeling through experiments. More specifically, the goals were to develop a novel numerical methodology to simulate the highly complex interaction between fluid flow and electrical fields. Next, to verify the model a mesoscale ion-injection pump was designed and fabricated, followed by a set of experiments that characterized the pump's performance. The experiments will also demonstrate the application potential of the concept in electronics cooling and particularly for spot cooling applications. Experimental tests were conducted on an EHD ion-injection mesopump to measure the flow rates and generated pressure heads with HFE -7100 as working liquid. It is shown that the results of two different flow rate measurement techniques that were employed, are in agreement. The experimental results also show that maximum flow rate of about 30 ml/min and pressure head of 270 Pa for the electrode gap of 250 m and voltage of 1500 V are achievable. A novel numerical modeling method was developed that incorporates both the injection and dissociation of ions. This modeling method is used to simulate the EHD mesopump. The numerical results show a fairly good agreement with experimental data.