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Huizing R.,University of British Columbia | Huizing R.,dPoint Technologies | Merida W.,University of British Columbia | Ko F.,University of British Columbia
Journal of Membrane Science

Membranes with high water vapour permeance and selectivity find many end uses including protective clothing, dehydration, and humidification. One application for water vapour transport membranes is in energy recovery ventilators (ERVs) for buildings. These devices improve building energy efficiency by transporting heat and moisture between incoming and outgoing air streams in building ventilation systems, effectively 'recycling' the energy used to condition the indoor air. Membranes for these devices must have high vapour permeance, and selectivity for water vapour over other gases and contaminants that may be present in the exhaust indoor air. Due to the high rates of water vapour transport required in these gas to gas devices, boundary layer and internal resistances within the membrane contribute significantly to performance. Commercially available membranes suffer from high water vapour transport resistance in the microporous substrate support layer. In this study we report the fabrication of novel impregnated electrospun nanofibrous membranes (IENM) for water vapour transport applications. Electrospun nanofibre layers are impregnated with a polyether-polyurethane solution and cured to create continuous thin impregnated fibre loaded film layers which are bound to a non-woven support layer. These membranes have high water vapour permeance and selectivity while eliminating the requirement for a microporous support layer which has high vapour transport resistance. Here we report initial studies on how controllable factors in the membrane fabrication (namely fibre loading and impregnated solution polymer solids concentration) affect structural and permeation properties of IENMs created. Membranes with adequate permeance and selectivity are demonstrated and direction for optimization is identified. We find that the nanofibre loading has a significant impact on water vapour permeability as the membrane thickness decreases. Future work will study how modifications to the geometric and structural properties of the fibres affect the membrane performance. © 2014 Elsevier B.V. Source

Ahluwalia R.K.,Argonne National Laboratory | Wang X.,Argonne National Laboratory | Johnson W.B.,W L Gore and Associates | Berg F.,Ford Motor Company | Kadylak D.,dPoint Technologies
Journal of Power Sources

Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer. © 2015 Published by Elsevier B.V. Source

dPoint Technologies | Date: 2010-05-17

Coated membranes comprise a porous desiccant-loaded polymer substrate that is coated on one surface with a thin layer of water permeable polymer. Such membranes are particularly suitable for use in enthalpy exchangers and other applications involving exchange of moisture and optionally heat between gas streams with little or no mixing of the gas streams through the membrane. Such membranes have favorable heat and humidity transfer properties, have suitable mechanical properties, are resistant to the crossover of gases when the membranes are either wet or dry, and are generally low cost.

dPoint Technologies | Date: 2012-12-19

A heat and humidity exchanger has example application in exchanging heat and water vapour between fresh air entering a building and air being vented from the building. The heat and humidity exchanger has a self-supporting core formed from layered sheets (

A water vapour transport membrane comprises a nanofibrous layer disposed on a macroporous support layer, the nanofibrous layer coated with a water permeable polymer. A method for making a water vapour transport membrane comprises forming a nanofibrous layer on a macroporous support layer and applying a water permeable polymer to the nanofibrous layer. The water permeable polymer can be applied for so that the nanofibrous layer is substantially or partially filled with the water permeable polymer, or so that the coating forms a substantially continuous layer on one surface of the nanofibrous layer. In some embodiments of the method, the nanofibrous layer is formed by electro-spinning at least one polymer on at least one side of the porous support layer. In some embodiments, the support layer is formable and the method further comprises forming a three-dimensional structure from the water vapour transport membrane, for example, by compression molding, pleating or corrugating.

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