Prior studies have shown that electric field in the form of fluid flow can be used for gas pumping and heat transfer enhancement. In this study, heat transfer enhancement by a two stage electrohydrodynamic (EHD) gas pump in a square channel is numerically analyzed. Using the finite difference and finite volume method respectively, the three-dimensional governing equations for the electric, flow and temperature fields are solved. The EHD induced flow in a square channel is calculated first, and its results are compared with the collected experimental data to validate the computational code. This study is implemented by a two stage EHD gas pump with different polarities for 24 emitting electrodes configuration to seek its effectiveness in the enhancement of heat transfer and pumping power requirement. To achieve the maximum enhancement, the emitting electrodes of the EHD gas pump are flush mounted on the channel walls so that the fluid flow produced directly disturbs the boundary layer thickness and improves the heat transfer coefficient. This is leading to a higher velocity near the channel walls and resulting in an inverted parabolic velocity profile at the center of the channel, which is opposite to the fully developed velocity profile of a forced flow. Both the current and fluid velocity inside the channel is obtained by positive and negative polarity.&nbsp;The EHD gas pump is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV. According to the findings, the EHD gas pump can produce and sustain gas flows with a maximum velocity and its maximum performance is better than conventional cooling fan. The influence of electric field on the flow and temperature fields is also examined for a wide range of Reynolds numbers (Re). The Reynolds numbers considered in this study varies in a range between 100 and 2000. At Re = 100, a maximum increase of average Nusselt number is achieved with an applied voltage of 28 kV. The pumping power required for the heat transfer enhancement is also critically evaluated. The enhancement produced by the EHD gas pump is found to be higher than other techniques and with a smaller power penalty. The overall effectiveness of the EHD gas pump in heat transfer enhancement is evaluated by the thermal hydraulic performance parameter, (Nu/Nu0)/(f/f0), which is always greater than unity. These results disclose that EHD technique has a great potential for many engineering applications, particularly for thermal management.

Enhancement of Heat Transfer by a Two Stage Electrohydrodynamic Gas Pump With Different Polarities

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.