Vacuum swing adsorption for R-32 recovery from R-410A refrigerant blend
Rui P. P. L. Ribeiro, Julio E. Sosa, João M. M. Araújo, Ana B. Pereiro, José P. B. Mota
Abstract
The recovery of high purity fluorinated gases from refrigerant blends is vital to promote a circular economy in the field of refrigeration and air conditioning. In this work, we evaluate the performance of a four-step Vacuum Swing Adsorption (VSA) process using activated carbon for the recovery of R-32 (difluoromethane) from a R-410A refrigerant blend—a binary mixture of R-125 (pentafluoroethane) and R-32 (yR−32=0.7; yR−125=0.3). Breakthrough curves were performed using dilute and bulk feed concentrations to determine mass and heat transfer parameters, which were then employed in simulations of fixed-bed adsorber dynamics. The mathematical model employed successfully predicts the experimental results of a four-step VSA cycle (feed, blowdown, purge, pressurization). The VSA performance was evaluated using process simulation. For a cycle time of 800 seconds (each step taking 200 s) and feed and regeneration pressures of 1.01 and 0.01 bar, respectively, R-32 is obtained with 97.0 mol-% purity and 30.9% recovery, with process productivity of 4.06 mol h−1 per kilogram of adsorbent, and energy consumption of 123.2 kJ/mol. Our results demonstrate the feasibility of using VSA processes for the recovery of R-32 from the near-azeotropic R-410A refrigerant blend.