A frosting limit model of air-to-air quasi-counter-flow membrane energy exchanger for use in cold climates

A theoretical frosting limit model is developed in this study for a quasi-counter-flow MEE. The frosting limit model uses analytical relationship between the onset of frosting at the coldest location of the exchange and the inlet air conditions. The model is validated with experimental data and consistent agreements are obtained between the theoretical and experimental data. Parametric studies are conducted using the validated model. The influence of airflow rates, exhaust air temperature and channel spacing on the frosting limit is rather limited compared to the diffusive resistance of moisture transfer. A membrane with improved moisture transfer properties is crucial to implement frost-free operation at normal indoor relative humidities.