C066 -- Employing Water Vapor-Selective Membranes for Sustainable Humidification of Ventilation Air

It is well known that indoor occupant comfort and health are tied to humidity levels. In warm seasons, dehumidification is required to maintain low indoor humidity conditions, however in cold months, indoor air is generally drier than would be desired. In this work, we present the unique application of the Active Membrane Energy Exchanger (AMX) concept to achieve heating and humidity recovery, while prior work on the concept has focused on cooling and dehumidification. The AMX employs selective membranes and heat exchange coils with a vacuum water vapor compressor for high efficiency, controllable humidity recovery and heat transfer. In this work, we derive system models for the AMX and baseline systems based on the first and second laws of thermodynamics to compare between the two. Specifically, we focus on understanding the capability of the AMX to recover humidity compared to membrane energy recovery ventilators (M-ERV). We conduct parametric calculations to understand the energy savings and exergy destruction of the AMX and baseline systems. We find the AMX to be reasonably capable of saving up to 35% of the energy spent on heating and humidifying air. Exergy destruction in the AMX was 13-33% lower than the baseline, except at exceptionally cold and dry conditions where the baseline actually used less energy and experienced less exergy destruction. Overall, the AMX shows great potential to operate as a sustainable heating and humidification device in cold climates (this study) in addition to its capability to operate as a high-efficiency cooling and dehumidification device (prior work).