DC discharges with a porous liquid anode: Increasing refrigerant efficiency for flash evaporation cooling with charged particle kinetics

摘要

The increasing heat flux of a functional device cannot be effectively taken through the simple increment of the liquid spay flux in a vacuum flash vaporization cooling process. Here we demonstrate that a new approach of increasing phase-change efficiency by coupling the charged particle kinetic energy in a DC discharge plasma with a porous liquid water anode can lead to the significant vaporization cooling enhancement effect under similar coolant evaporation rate. Systematic experiments on heat conduction and plasma diagnostics with controlled groups (liquid-free and plasma-free) allow us to describe the correlation patterns of the characteristic properties among a flash evaporation fluid, discharging plasma, and the cooling effects, in detail. It is observed that the temperatures of the working fluid (water) and the metallic heating target have been decreased by 9 and 12 °C, respectively, in plasmas, which is -80% effective than the controlled cases without plasmas. It is also found that the coolant molecules have been partially ionized, and pumped into a much higher energy state through the discharging collisions, where the rotational temperature of OH(A-X) transition is more than 2000 K based on the diagnostics of the optical emission spectrum. The plasma enhancement effect explored in this work opens novel ways to increase and control the heat flux taken by the vacuum flash vaporization cooling.