Experimental investigation of a condensation particle counter challenged by particles with varying wettability to working liquid

The counting efficiency of an in-house laminar flow Condensation Particle Counter (CPC) was investigated experimentally. The CPC was challenged by different sources of particles (ambient particles, and combustion particles generated from CH₄ and C₂H₄), and the counting efficiency of the in-house ultrafine CPC (IUCPC) was obtained by comparing particle concentration data measured by the IUCPC with that measured by a reference instrument, TSI CPC 3775. The counting efficiency is closely related to the contact angle (an indication of the wettability of particles by the working fluid) and the combination of the saturator and the condenser temperatures. The particles from different sources appeared to have different contact angles, in other words, different wettability by the working liquid.