Green Engineering of Low-GWP Refrigerant Blends: Risk Assessment and Product Characteristics

To address the environmental threat of fluorinated gases, blended refrigerants can balance the environmental benefits of low GWP refrigerants with their inherent flammability. Therefore, this study tested the combustion characteristics of HFO-1216/HFC-161 and HFO-1216/HFC-32, and analyzed the products generated during their oxidative pyrolysis. The results indicate that, as the HFO-1216 proportion increases, the flammability range and maximum explosion pressure of HFC-161 first expand and then decrease, while the corresponding parameters for HFC-32 continue to decline. The higher the proportion of HFO-1216, the lower the peak rate of maximum pressure rise of HFC-32 and HFC-161. Then, as the proportion of HFO-1216 increases, changes in toxic products CO, HF, and COF2, as well as the amount of environmentally impactful CO2, were analyzed. The efficiency of HFO-1216/HFC-161 carbon atoms converting into CO and CO2 first increases and then decreases, whereas in HFO-1216/HFC-32, it uninterruptedly decreases. Finally, as the temperature rises, the generation rates of toxic products HF, CO, and COF2 from the two mixed working fluids increase. Compared to HFO-1216/HFC-32, HFO-1216/HFC-161 generates more toxic products. This study provides a new perspective for analyzing the combustion characteristics of HFOs/HFCs.