Pyrolysis mechanism of HFO-1234yf with R32 by ReaxFF MD and DFT method

Abstract

The pyrolysis mechanism of pure HFO-1234yf and R32 is investigated by ReaxFF molecular dynamics simulation(MD) and density function theory (DFT) calculation. There are 15 initiation reaction pathways observed in the process of pyrolysis. The pyrolysis processes of mixed working fluid (HFO-1234yf/R32) are carried out at different temperatures and different ratios of mixture. The results show that R32 can restrain the decomposition of HFO-1234yf at 2600 K–2800 K and promote one of HFO-1234yf after 3000 K. This is also demonstrated by the kinetic analysis. The radical CHF2 from the decomposition of R32 plays a significant role and can obviously decrease the energy barrier of all the decomposition pathways of HFO-1234yf after 3000 K based on the analysis of DFT. HF is the dominant product in the all pyrolysis processes. In the mixture, R32 slows down the formation of HF at 2600 K–3100 K, but increase the quantity of HF at 3200–3500 K.