Moderated, Water-Based, Condensational Particle Growth in a Laminar Flow

Presented is a new approach for laminar-flow water condensation that produces saturations above 1.5 while maintaining temperatures of less than 30 degrees C in the majority of the flow and providing an exiting dew point below 15 degrees C. With the original laminar flow water condensation method, the particle activation and growth occurs in a region with warm, wetted walls throughout, which has the side-effect of heating the flow. The moderated approach presented here replaces this warm region with two sections-a short, warm, wet-walled initiator, followed by a cool-walled moderator. The initiator provides the water vapor that creates the supersaturation, while the moderator provides the time for particle growth. The combined length of the initiator and moderator sections is the same as that of the original, warm-walled growth section. Model results show that this new approach reduces the added heat and water vapor while achieving the same peak supersaturation and similar droplet growth. Experimental measurements confirm the trends predicted by the modeling. Copyright 2014 American Association for Aerosol Research