Particle Activation Probability in n-butanol based Condensation Particle Counters

The effect of chemical composition of aerosol particles on the counting efficiency of a TSI 3790 condensation particle counter (CPC) was theoretically and experimentally investigated. The activation probability was determined from thermodynamic theories (Kelvin, Köhler) and a kinetic theory (heterogeneous nucleation). The saturation ratio of n-butanol, the CPC working fluid, and particle losses were numerically obtained from the infinite series solution of the Graetz problem. Experimental measurements of counting efficiencies of diesel soot, emery oil, and Combustion Aerosol Standard soot particles were in reasonable agreement with heterogeneous nucleation theory predictions (contact angle ¿~10-12°), whereas the experimental counting efficiency of tetracontane (C40) particles fell in between predictions of Köhler theory (completely soluble particle in n-butanol) and ¿=0° heterogeneous nucleation. The Kelvin equation did not provide a reasonable approximation to the calculation of particle activation in the n-butanol CPC.JRC.DDG.H.4-Transport and air qualit