Heat Transfer in Atmospheric Pressure Non-equilibrium Plasma and Suppression of Joule Loss by High Voltage Pulses.

Abstract

Fundamental properties of the process of heat exchange between atmospheric pressure non-equilibrium plasma and solid wall have been inventigated by focusing on a surface discharge. The surface discharge was exposed to air and nitrogen jet impingement to secure the flow field as well as feed gas supply, and in situ measurement of the wall temperature was employed by thermography. About 80% of the discharge power was measure as heat flow to the wall and heat transfer rate was dominated by the generation of Joule heat. On the other hand reaction enthalpy or recombination of electric charges showed minor effect on heat transfer rate due to the low degree of ionization. Such Joule loss was successfully suppressed by 50% with the fast rising pulsed voltage, which is well-known technique to minimize ion current, thus heat flow rate to the insulating wall could be also halved compared to the results obtained with the high frequency sinusoidal voltage (10 kHz-80 kHz).