Membrane, Dehumidification, Ventilation, Heat Exchanger, Energy Savings
As concern for indoor air quality grows, many buildings will likely opt to provide higher rates of outdoor air than would traditionally be specified. This imposes a challenge on air conditioning systems since the latent loads associated with ventilation air are much higher than those associated with recirculated air. Membrane-based technologies, which enable mechanical separation of water vapor from air, have recently emerged as promising candidates for efficiently providing dehumidification, however, limitations remain. To date, most modeling work on these types of systems has focused on 100% outdoor air configurations that employ isothermal dehumidification designs. However, we have proposed a design referred to as the Active Membrane Energy Exchanger (AMX) that integrates cooling and membrane dehumidification into one device (thus non-isothermal) for a range of benefits. This work presents a specific application of the AMX in a system configuration that includes the treatment of both outdoor ventilation air and recirculated air. The system’s performance is analyzed over a broad range of ambient conditions and the effect of ventilation rates on the system performance is studied in detail. This configuration is found to be capable of providing three times the ventilation air of conventional systems with comparable or less energy consumption for the given conditions. Additionally, the optimal membrane module-outlet air temperature is found to be 18-20 ℃. Lastly, a case study using EnergyPlus building simulations shows that this configuration can reduce annual cooling energy requirements by as much as 34% in hot and humid cities for buildings with high latent loads and high ventilation rates.