HEPA Filtration in Smart Cabin Air Filter Systems for Vehicles
Jérôme Migaud, CHRISTOPH KRAUTNER, Thomas Siegele, Martin Lehmann,
MANN+HUMMEL GmbH Abstract Number: 641
Working Group: Control and Mitigation Technology
AbstractRecent studies show: 90% of all airborne particles are ultrafine particles. UFPs are easily inhaled. They can reach the pulmonary alveoli and affect health. Vehicle occupants are confined to only a few cubic meters without any dilution effects. As a result, the air pollution inside a vehicle cabin can be up to five times higher than outside. Therefore, solutions are needed to protect vehicle occupants.
To improve the air quality in the vehicle we have developed the Smart Cabin Air Filter system which includes up to three filters: a prefilter, a HEPA* filter and an HVAC filter. The prefilter removes coarser particles, thus protecting the HEPA (High Efficiency Particulate Air) filter from clogging and maximizing its lifetime. HEPA is designed to remove ultrafine particles from the air and can remove more than 99.95% of those particles. In addition, a particulate sensor controls the PM2.5 concentration in the incoming and outgoing cabin air and actively monitors the filters. Based on the CO2 level in the cabin, a flap controls the incoming air supply. The HEPA filter is activated only when the outside air is extremely polluted, e.g. in a tunnel or traffic jam. The smart control flap system, combined with an algorithm, adjusts and triggers the system’s air modes.
We retrofitted an electric car with such a system to prove its benefits. In this scenario, a high-efficiency combi filter with antimicrobial properties and activated carbon for adsorption of odors and harmful gases like SO2, NO2 and VOCs is used as a prefilter. A UV-C device has also been added to neutralize microorganisms. UFPs and PM2.5 filtration efficiency and energy consumption were measured. Thanks to digital solutions, drivers and passengers can monitor the air quality in the cabin.
*Tested according to DIN EN 1822