Enhancing electrospray cooling via electrode ring: An experimental and numerical study

Electrospray cooling is a promising technique for its high heat transfer efficiency and extreme low coolant and energy consumption. However, few articles focused on the enhancement of electrospray cooling using auxiliary electrodes. Moreover, there is no article referring to the numerical model for electrospray cooling with auxiliary electrode. Herein, we develop a numerical model and set up an experimental system to explore the influence of electrode ring on electrospray cooling. Results demonstrate that the potential difference between the electrode ring voltage and the capillary voltage determines the electrospray mode, and the electrode ring can enlarge the atomization angle and increase the velocity of the atomized droplets, thereby intensifying electrospray heat transfer coefficient. When the electrode ring is grounded, the capillary-ring electric potential rises, causing both increases in charge density and average velocity of cone jet. When the total voltage is the same in the cone-jet mode, the grounding electrode ring can reduce the wall temperature by 7.5 %. In the cone-jet and multi-jet modes, the larger the total voltage of capillary tube and electrode ring, the better the cooling effect. Increasing the inner diameter of the electrode ring from 2 mm to 4 mm and 6 mm can respectively improve heat transfer coefficient by 49.3 % and 116.7 %.