Optimization Method for C₄F₇N Gas Mixture Based on Flory Huggins Model

At present, most insulation gases need to be mixed with other neutral gases to avoid the phenomenon of gas liquefaction when the ambient temperature is too low. If neutral gases are selected through experimental methods, the research cycle is long and the workload is large, which brings great difficulties to the research work. In this paper, $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N}$ gas as an example, based on density functional theory and Flory Huggins mixing model. By calculating the interaction factors between two gases in the gas mixture, it is found that the compatibility of $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N}$ gas mixed with CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> is better than that of $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{N}_{2}$, $\mathrm{SF}_{6} / \mathrm{N}_{2}$, and $\mathrm{SF}_{6} / \mathrm{CO}_{2}$ gas mixtures. Furthermore, the binding structure and binding energy between $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{CO}_{2}$ and $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{N}_{2}$ molecules were calculated under different ratios. The results showed that the $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{CO}_{2}$ gas mixture was more stable than the $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{N}_{2}$ gas mixture. Meanwhile, when the $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N}$ content is low, the stability of the $\mathrm{C}_{4} \mathrm{~F}_{7} \mathrm{~N} / \mathrm{CO}_{2}$ gas mixture is better. This method can greatly shorten the research cycle of insulation gas mixtures, and can also be extended to multicomponent gas mixtures, which is conducive to efficiently and accurately finding more suitable neutral gases as mixed insulation gases for environmentally friendly gases, and can promote the efficient research and development of environmentally friendly gas insulation equipment.