561 / 2017-05-14 16:40:49

Thermophysical Properties Calculation of C4F7N/CO2 mixture Based on Computational Chemistry ——A Theoretical Study of SF6 Alternative

C4F7N/CO2 mixture,Thermophysical Properties,SF6 Alternative

An SF6 alternative gas based on C4F7N mixed CO2 has attracted great attention in recent years. The related experimental reports show that it has good insulation, thermal dissipation, switching performances and other characteristics. In theoretical research area, the plasma thermophysical properties are of great significance to study the microscopic mechanism of arc plasma breaking process and arc plasma simulation. However, for C4F7N, due to the relatively large molecular formula, the decomposition process of the arc process is complex. For some relevant gas particles，the spectral parameters are lacking. Reasons mentioned above caused that the thermophysical property studies related C4F7N are rarely reported.
In order to obtain the decomposition process, it is assumed that the decomposition of C4F7N molecules during arc combustion is carried out in the form of covalent bond cleavage. Then the main decomposition path and decomposition products of C4F7N can be obtained by analyzing the molecular bond energy. The relevant parameters of gas particles lacking of spectral parameters, were calculated from the molecular structure using computational chemistry software. Based on the composition results, which assume local thermodynamic equilibrium, the transport properties including viscosity, thermal conductivity and electrical conductivity of C4F7N-CO2 are calculated in the temperature range from 300 to 30000 K at pressures between 0.1 and 16 atm, using Chapman enskog method. For the collision integrals, the phenomenological potential was adopted.