The calculation of the decomposition products of C5F10O–CO2 mixtures with a chemical kinetic model

Abstract

This paper presents a chemical kinetic model to investigate the physicochemical process in C5F10O-CO2 mixtures. The model contains 12 ions, including e, C+, O+, C2 +, O2 +, CO+, CO2 +, O−, C−, C2 −, O2 −, O3 − and 38 neutral species, containing C, O, C2, O2, CO, CO2, O3, C5F10O, C4F7Oa, C4F7Ob, C4F7Oc, C4F7Od, C3F5O, C3F4Oa, C3F4Ob, C3F4Oc, C3F4Od, C3F4Oe, C3F3Oa, C3F3Ob, COCF3, C2F2Oa, C2F2Ob, COFC, COF, C3F7a, C3F7b, C3F6a, C3F6b, C2F5, C2F4a, C2F4b, C2F3a, C2F3b, C2F2, CF3, CF2, CF. The total number of 180 reactions are considered. For the reactions whose forward and reverse rate constants can be obtained, the reactions are split into two one-way reactions. In addition, the reactions which produce photons are also considered as one-way reactions. The other reactions are reversable. The reverse rate constants can be obtained by the ratio of the forward rate constants and the equilibrium constants. The molar fractions of the decomposition products in C5F10O-CO2 mixtures with the C5F10O content to be 5%, 7% and 13% are calculated in the temperature range of 500–3500 K. The ratio of the electron temperature to the temperature of the heavy species is calculated to obtain the deviation from local thermodynamic equilibrium in different temperatures. The characteristic decomposition products in different temperature ranges are determined. In addition, the main reaction pathways for the main species are determined by analyzing the contributions of the corresponding reactions to the generation and consumption of the species. In order to validate the chemical kinetic model, the molar fractions of the species in pure CO2 are compared with those by Gibbs free energy minimization in a wide temperature range. This model can help better understand the physicochemical process from the aspect of the reactions during the over-heat fault, and the characteristic decomposition products in different temperature range can help identify the potential fault to avoid great power accidents.