Enhancement of Gas Pumping and Heat Transfer Using a Two-Stage Electrohydrodynamic Pump Operated at Uneven Applied Voltage

摘要

A two-stage electrohydrodynamic (EHD) gas pump inside a square channel is numerically examined for its potential in the enhancement of gas pumping and heat transfer. The gas pump with 28 emitting electrodes in each stage is charged at a combination of three different operating voltages (20 kV, 24 kV, and 28 kV) for the possible performance improvement. The emitting electrodes are flush mounted on the channel walls so that the corona wind produced can directly disturb the development of momentum and thermal boundary layers to create maximum enhancement in gas pumping and heat transfer. 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 the enhancement is evaluated using the thermal hydraulic parameter, (Nu/Nu_0)/(f/f_0), which is defined as the ratio of heat transfer enhancement over the power penalty. It is found that this parameter is always greater than unity for the EHD pump considered. These results reveal that EHD gas pump has a great potential for applications in thermal management and can be more energy-efficient when operated with uneven applied voltages.