Heterogeneous Condensation of Water Vapor on Nanoparticles in a Membrane-Based High-Flow Process Monitored by a New In Situ Measuring Cell

摘要

This article presents a membrane-based process to improve separation efficiency of airborne particles by heterogeneous condensation of water vapor. A plant was set up in laboratory scale to control the supersaturated state of water vapor in air accurately. Droplet growth due to heterogeneous condensation is investigated experimentally and supersaturation is calculated by solving the differential equations for heat and mass transfer in a laminar gas flow. The apparatus is based on a water condensation particle counter (WCPC). It operates with several growth tubes in parallel thereby allowing higher aerosol throughput. The increase of particle size based on heterogeneous condensation is detected by an in situ measuring system. Therefore a new measuring cell was operated with well-defined test aerosols differing in wetting abilities and initial nuclei size. First results of particle activation and condensational droplet growth are presented.