The enhancement effect and competition behavior of a flash evaporation system with a continuous DC glow discharge plasma

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• A DC continuous glow discharge is demonstrated to enhance flash evaporation cooling. • The temperature drop, pressure and evaporation mass generally increase with current. • The gas temperature of plasma increases with current. • The rotational temperature and electron density of plasma are independent of current. The transient plasma kinetic has been proved to be able to significantly improve the refrigerant efficiency of vacuum flash evaporation. Here we explore the flash evaporation cooling enhancement effect induced by a continuous glow discharge plasma, generally exists in vacuum, but the heat deposition is more severe than a transient plasma source. Several controlled groups with different discharge currents, which determine the thermal deposition rates, are subjected to an oscilloscope, CCD, and optical emission spectroscopy (OES) for diagnosis of plasma and Infrared Radiation (IR) thermography, vacuum gauge, and electronic balance for thermal and evaporative properties to reveal the influence of plasma characteristics on flash evaporation cooling. The characterization results of plasma show that the translational temperature increases with current while the rotational temperature and electron density are almost independent of current. Compared to plasma-free, the plasma generally leads to a significant increase in the maximum temperature drop ( Δ T max ), but the effect increases with current from 0.95 to 3.07 mA and decreases at 3.87 mA. The behavior is attributed to the competition between the positive effect of evaporative cooling enhancement resulted from particle kinetic and the negative effect of joule heat itself. This has also led to that the system presents a best cooling enhancement efficiency defined by the increased Δ T max per unit watt due to plasma, ( Δ T max ( I ) − Δ T max ( Plasma − free ) ) / P , at the current of 2.01 mA for our cases. In conclusion, the continuous DC glow discharge plasma has been demonstrated to be useful to enhance flash evaporation cooling.