Brownian coagulation of aerosols at low Knudsen number

Abstract

Dibutyl phthalate aerosols of narrow size distribution have been prepared in a falling-film generator using nitrogen rather than helium as the carrier gas. The Knudsen number in nitrogen is considerably lower so that the Cunningham correction is much less. A large number of coagulation experiments give average coagulation times in excellent agreement with theory. However, the spread of the values is much greater than obtained earlier in helium. The spread of the results reported here may be due to the lower thermal conductivity of nitrogen.