ABSTRACT
Diffusion is the primary means of transportation and deposition of small airborne particles and gaseous molecules in a low air velocity field. For large particles and flow fields with high velocity, gravitational settling and convection become the primary means of transportation and deposition. A variety of applications of particle diffusion are found in air-quality instrumentation and control technologies. Typical applications include diffusive batteries for the study of size distribution of small particulate matters, and denuders to separate gaseous molecules from particles. This chapter will review the parameters that determine the particle diffusion coefficient, and then discuss the applications of particle diffusion for typical instrumentation and air-cleaning technologies.
