Transport Coefficients of H2–Cu/Al2O3 Plasma Mixtures Considering Solid and Liquid Status

Abstract

Obtaining the plasma transport coefficients of the mixed system of arc-extinguishing medium and erosion product is the precondition of numerical simulation of erosion–diffusion in an arc chamber. In this article, the minimum Gibbs free energy method was used to calculate the composition of the H2–Cu/Al2O3 system, including solid and liquid copper (aluminum oxide), because copper and aluminum oxide are commonly used as electrode and ceramic materials in hydrogen dc contactors, respectively. The transport coefficients of H2–Cu/Al2O3 system and the phase transition of erosion products provide the basis for the subsequent simulation of erosion–diffusion of electrode and arc chamber in the H2 plasma. Results revealed that: 1) in the low-temperature range, copper (aluminum oxide) mainly exists in the form of a solid or a liquid state, resulting in the transport coefficients of the H2–Cu/Al2O3 system consistent with that of the H2 system; 2) as temperature increases, the copper (aluminum oxide) undergoes gasification (sublimation–decomposition) reaction that exists in a gaseous state and begins to affect the transport properties of the H2–Cu/Al2O3 system; in particular, the proportion of copper (aluminum oxide) has the most significant effect on viscosity; and 3) as the temperature continues to rise, atoms and molecules in the H2–Cu/Al2O3 system are completely ionized and the proportion of copper (aluminum oxide) has little effect on the transport properties (except electrical conductivity) of the H2–Cu/Al2O3 system. Finally, the transport coefficients of H2–Cu/Al2O3 plasma mixtures are reliable enough, in engineering application aspect, to be applied for simulation of erosion–diffusion in hydrogen dc contactors.