抄録
This work is a computational approach of transport (electrical & thermal conductivities) and ther-modynamic (enthalpy & density) properties of SF6 gas polluted with Al vapor, which are the basic data necessary for the prediction of the behavior of high power arcs in GISs (Gas Insulated Switchgear) or between ACSR conductor. These calculations provide also a profile of electric field vs arc current for wall-stabilized arcs. Calculations have been done for a wide range of the temperature from 15, 000 K to 30, 000 K at a pressure of 0.4 MPa with the vapor admixture ratio from 0% to 50%. The results show that the electron density and the electrical conductivity are enhanced by Al vapor with relatively lower ionization potential even though a large number of electrons are expended to form F- through recombination, especially at temperature 4, 000_??_8, 000 K. For instance, at 5, 000 K electrical conductivity σ is 0. 16 S/cm while it is 0.88 S/cm and 1.8 S/cm for 10% and 50% of Al vapor contamination, respectively. But below or near 3, 000 K, number of free Al atoms are nearly zero as they all remain in the molecular form of AlF and AIF3 resulting almost no effect upon the electrical conductivity. The thermal conductivity is found to change only under heavily, more than 10%, contaminated condition of Al vapor. It decreases below 5, 000K due to waning of SF6 molecule whereas it increases from 5, 000K to 8, 000K due to the reaction thermal conductivity by the breakdown of AlF. The effect of Al vapor inclusion upon enthalpy and density is almost negligible. In order to provide a typical example for using obtained data, a study has been performed for prediction of the behavior of wall-stabilized SF6 gas arcs using the transport properties of the gas contaminated with Al vapor. Results indicate that the electric field intensity and axis temperature of arc at a certain value of arc current decrease for Al vapor inclusion. These reductions in the electric field intensity and the axis temperature are the reflections of input power contraction and of pressure suppression inside the tank, respectively.
