Evaluation of High Flow Rate Mixing Type CNC

Abstract

Mixing type CNC (Condensation Nucleus Counter), one of the typical three types of CNC's, where an aerosol is mixed with heated air saturated by a certain vapor to produce supersaturation, has been evaluated. Counting efficiency of the CNC (flow rate : 2.8 l/min, particle size : 4-20 nm) was observed by an electrometer for three kinds of condensing vapor, 1)ethylene-grycol, 2) di-ethylene-grycol and 3) tri-ethylene-grycol. The best result, where efficency was about 70 % with 5 nm particles, was observed for di-and tri-ethylene-grycol vapor. Experimental results are discussed from the view point of super-saturation produced and the amount of condensing vapor which are calculated for various operating conditions and vapor used, and factors affecting performance of mixing type CNC have been made clear.