Removal of R134a from air/R134a mixture based on cryogenic condensation method

The emission of greenhouse gases is aggravating the global warming. Nowadays, R134a is widely used in refrigeration engineering, and its globe warming potential (GWP) is relatively high (1301). So, it is imperative to recover the R134a in refrigerating devices, and prevent it from being released to the atmosphere. In present study, the R134a/nitrogen mixture is cooled by cryogenic nitrogen and R134a is removed and captured based on the different boiling point of the mixture. The self-programming approach was adopted to calculate the heat and mass transfer process of the mixture in different molar concentration in a sleeve-type heat exchanger with recuperating. The results of the calculation shown that, the required length of the heat exchanger is different under various molar concentrations. The temperature distribution of the mixture gas, the wall temperatures of the heat exchanger and the cold nitrogen, as well as the molarity and the accumulation of R134a at different length are also computed and plotted into graphs. From the obtained data, it could be found that the molar concentration of R134a in the mixture could be reduced to 100ppm which is low enough to discharge. This work could be referenced by further studies and engineering applications.