Gas Heating Mechanisms in Atmospheric Pressure Helium Dielectric-Barrier Discharges Driven by a kHz Power Source

Abstract

The present work investigates contributions of different heating mechanisms and power efficiency of atmospheric-pressure helium dielectric-barrier discharges (APHeDBDs) containing a small amount of N2 for temperature measurements by developing the numerical methodology combining the one-dimensional (1D) plasma fluid model (PFM) and 3D gas flow model (GFM) with simulated results validated by measurements including the discharge power consumption and temperature distribution. The discharge dynamics are modeled by the 1D PFM for evaluating the average heating source considering elastic collision, ion Joule heating, and exothermic reactions as the source term of energy equation solved in the 3D GFM. The simulated current density reaches 29 A m−2 which is close to that measured as 35 A m−2. The simulated power consumption is 2.0 W which is in good agreement with the average measured power consumption as 2.1 W. The simulated average gas temperature in the reactive zone is around 346 K which is also close to the rotational temperature determined. The analysis shows that elastic collision and ion Joule heating are dominant heating mechanisms contributing 23.9% and 65.8% to the heating source, respectively. Among ion species, N2+ and N4+ are dominant species contributing 44.1% and 50.7% to the heating source of ion Joule heating, respectively. The simulated average total heating source is around 5.6 × 105 W m−3 with the maximum reaching 3.5 × 106 W m−3 in the sheath region due to the contribution of ion Joule heating.

Characterization of OH species in kHz He/H2O atmospheric pressure dielectric barrier discharges

“…Therefore, the van der Waals broadening is neglected in this work without losing the analysis accuracy. The average gas temperature in the reactive zone is characterized as around 370 K by the methodology developed previously [37]. The heating source generated in the reactive zone is evaluated by the 1D PFM considering the energy released mostly from elastic collisions and ionic Joule heating and is provided as the source term of the energy equation solved in the 3D gas flow model to model the temperature distribution of the reactor with the distribution of surface temperature validated by the temperature distribution measured by an infrared thermal imager.…”

“…The previously developed 1D PFM is employed to characterize the discharge behavior and OH chemical kinetics of helium APDBDs with different H 2 O concentrations under the assumption of uniform glow discharge generated between the gap [37]. The simulation domain is comprised of a 5 mm discharge gap and 0.7 mm glass plates at both sides of the gap, which is identical to the experimental configuration.…”

“…Then species densities are calculated with the integration of electron dynamics. Detailed descriptions of the developed 1D PFM can be found in the previous work [37].…”