Membranes for Air-to-Air Water Vapor Exchangers

Energy recovery ventilation (ERV) is an emerging application for polymeric membranes used in energy efficient building ventilation systems. In these enthalpy exchange devices, heat and moisture are transported through a membrane between fresh supply ventilation air streams and stale building exhaust air streams.  Membranes for these devices must have high water vapor permeance and good selectivity of water vapour over indoor air contaminants.

This presentation will discuss ongoing membrane research and development efforts at dPoint Technologies. Experimental results on multi-layer membrane structures based on several substrate platforms are presented, demonstrating the contribution of substrate and selective layer resistances to transport in these air-to-air transport devices. Several selective layer polymers are also discussed and results are reported in terms of water vapour permeability and selectivity for water vapour over gases and volatile organic compounds. The thermal effects on permeability in these polymers and interactions of water and water vapour with these polymers are also discussed. Specifically development of the "Gryphon" series of membranes will be discussed, these blended membranes are designed to have low VOC transport under humid air conditions. Results from mixed gas studies demonstrate how high humidity impacts selectivity when using various polymers. Focus areas for future membrane, exchanger, and process research will be discussed.