This paper reports the theory and modeling of a nanoparticle monitor, the condensation particle counter. A four-point finite difference implicit approach and Crank-Nicolson approach are utilized for the model and nonuniform grids are adopted. The simulated results have revealed that the four-point finite difference implicit approach is in good agreement with the previous studies, while the stability and precision are improved. This paper numerically validates the feasibility of high temperature condensation particle counter, which was proposed by Cambrige to replace the existing particle measurement program. The result shows that the cut-off size is 4 nm, thus eliminating the effect of volatile compounds. At last, the depletion of working medium is verified, which is caused by working fluid condensing on the particles, thus lowering saturation ratio can be safely neglected.

aerosol  /  condensation particle counter  /  numerical simulation  /  nonuniform grids  /  counting efficiency