(65a) Hollow Fiber Membrane Module Fabrication for the Separation of R-410A

Hydrofluorocarbon (HFC) refrigerant mixture separation has become a pressing issue due to legislation calling for a gradual phase out because of their high global warming potential. Currently, there are no viable solutions for separating HFC mixtures that are cost effective, energy efficient, and environmentally conscious. Fluoropolymer membranes can provide a solution to separate HFCs in a way that reduces wasted refrigerants and aids in their phase out. Previous research has shown that fluoropolymers can be used on a small scale with membrane films, offering high separation but low permeation. However, industrial scale separation requires higher surface area. This research aims to scale up the membrane separation from polymer films to thin films on hollow fiber supports. The analytical research examines the efficacy of hollow fiber supports coated with thin layers of perfluoro(butenyl vinyl ether) (PBVE) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) copolymers to increase the scale of difluoromethane (HFC-32, CH₂F₂) and pentafluoroethane (HFC-125, CHF₂CF₃) separation as previously investigated in literature. An in-depth study of membrane module fabrication focusing on lab scale methods to test hollow fibers was completed and several iterations of fiber potting methods were tested to find a material and technique suitable for use in experiments. Research is in progress to optimize fiber supports for high gas permeation and proper adhesion of polymer coating. A dip-coating method is used to apply a one-micron thick layer of 30 mol% PBVE-co-70 mol% PDD, and SEM imaging is used to ensure even coating and minimal defects of the coating. The fibers were then tested in a membrane module and measurements for selectivity and permeation showed promising results for scaled-up industrial separation use.