ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract An apparatus is described for the study of aerosol particle condensation in a plume of vapour rising from a heated source. The principal advantages of this plume chamber over the heat-pulse cloud chamber previously used include the attainment of steady-state conditions at a controlled source temperature and the suppression of recirculation. The coagulation of particles and the further growth or re-evaporation that tends to occur in the outer zone of the heat-pulse equipment is discouraged, and samples taken on substrates positioned in the plume are expected to be more representative of the original nucleation and growth processes. Aerosol particles were condensed in zinc vapour emitted at various source temperatures (T 0) with the walls at room temperature (T ∞). Trends occur in particle size and morphology when T 0 is varied at fixed T ∞ which broadly resemble those in the cloud chamber work, where T ∞ is varied. Thus, in addition to the dendrites and prisms typical of low T 0 there is an increasing proportion of spheres when T 0 is raised above the melting point, until they eventually become the only species present. The particles condensing in the invisible fume generated at T 0 settings below the melting point, were found to consist only of prisms and dendrites. This confirms that these particles condense directly in the solid state, unlike the spheres, which are originally liquid. The trends observed when changing T 0 at constant T ∞ are shown to be in agreement with theoretical predictions for nucleation in a boundary layer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00549836
