Thermodynamic Properties and Transport Coefficients of C4F7N/CO2/PTFE Mixtures arc Plasma

The physical parameters of arc plasma are a prerequisite for conducting arc magnetohydrodynamic(MHD) calculations, which are crucial for understanding the extinguishing capabilities of $\mathbf{C}_{4}\mathbf{F}_{7}\mathbf{N}$ mixed gas. The self-blast circuit breaker (CB) has an arc blocking effect when interrupting the fault current, causing the ablation of nozzle material and form PTFE vapor, which mixes with $\mathbf{C}_{4}\mathbf{F}_{7}\mathbf{N}/\mathbf{CO}_{2}$. In this paper, the thermodynamic properties and transport coefficient of $\mathbf{C}_{4}\mathbf{F}_{7}\mathrm{N}/\mathbf{CO}_{2}/\mathbf{PTFF}$ mixed gas are calculated, and the effects of gas pressure and PTFE volume fraction on the arc plasma physical parameters are explored. The results show that the higher the gas pressure, the higher the density and the electric conductivity of the plasma, which suppresses particle dissociation and ionization reactions, reduces the peak specific heat and thermal conductivity of the plasma, and moves towards high temperature regions. The volume fraction of PTFE has minimal impact on the thermodynamic properties of the plasma at the same gas pressure. An increase in the PTFE volume fraction results in a decrease in thermal conductivity and an increase in viscosity and electric conductivity.