CH-24-C050 - Test Methodology to Determine Aerosol Transfer in Membrane Energy Exchangers

Ventilation systems are generally designed to meet occupant comfort and air quality requirements, but not for infectious disease control. However, by increasing the amount of clean fresh outdoor air, the concentration of bio-aerosols indoors can be decreased thereby reducing the chances of airborne transmission of diseases. Membrane energy exchangers are energy saving devices that can be used to precondition outdoor air by recovering energy from building exhaust air. A recent study has shown that aerosols deposit inside these exchangers (Engarnevis et al. 2017). These deposited aerosols could be transferred to the supply air into the building which would hinder the application of energy exchangers in some situations, such as during a pandemic. The ratio of the aerosols transferred from the building exhaust air stream to the supply air stream can be defined as the exhaust contaminant transfer ratio (ECTR) and is an important parameter to quantify. ISO A-3 test dust and lab safe E-coli bacteria aerosols are used in this research to determine the ECTR in a small-scale experiment facility. A test method is proposed for lab-scale experiments and the method is applied to a dense membrane. Preliminary test results indicate no aerosol transfer for particles in the size range 0.3 ??m – 10 ??m (PM 2.5 and PM 10) and E-coli in the tested membrane.Future work will use this test methodology with different porous membranes.