Design and performance characteristics of a turbulent mixing condensation nuclei counter

The design and optimization of operation parameters of a Turbulent Mixing Condensation Nuclei Counter (TMCNC) are discussed as well as its performance using dibutylphthalate (DBP) as the working fluid. A detection limit of 3 nm has been achieved at a Row rate of 2.8 l min(-1) (0.1 cfm). In addition, the effect of saturation temperature on particle growth in the TMCNC was investigated to identify the temperature range where particles could grow to a detectable size regardless of their initial sizes and materials. Size distributions of particles after condensation growth were measured as a function of saturation temperature for three types of nuclei: atmospheric aerosol particles, monodisperse NaCl particles, and liquid DBP particles generated by homogeneous nucleation. The size distribution after condensation growth can be described by a log-normal distribution with sigma(g) = 1.2-1.3. The modal diameter of the size distribution can be predicted by the classical equations for particle growth in supersaturated media. The final particle size distribution is a function of the initial particle diameter unless the saturator temperature is above 125 degrees C. (C) 2000 Elsevier Science Ltd. All rights reserved.