The Effect of Relative Humidity on Coagulation and Surface Losses of Ammonium Chloride Smoke

Abstract

Studies have been made of the change with time in the particulate number and rate of loss to surfaces of ammoniunl chloride smoke a t various relative humidities ranging from 15% to 98%. The results are adequately described by the theory given previously with appropriate values for the loss and coagulation constants. The rate of disappearance of the smoke increased with increasing relative humidity, particularly above a value of about 60%. This circumstance is due to an increased loss rate from the system and not to increased coagulation. Though the possibility of 'protecting' an aerosol against coagulation is remote, it would appear possible to render certain aerosols more persistent in humid atmospheres by treatment affecting loss processes rather than coagulation.

The effect of the electric charge distribution on the ageing of an aerosol

“…The experiments were carried out in a 0*2 m3 wooden cube fitted with surface-loss samplers similar to those described by Gillespie & Langstroth (1951a). These samplers allowed a direct determination of the number of particles lost to the chamber surfaces during successive periods throughout an experiment.…”

“…The values of these constants were obtained by an analytical treatment of appropriate particle number and surface-loss data. The details of the method have been described elsewhere (Gillespie & Langstroth 1951a) and a brief summary is given below. For various aerosols having quite similar size distributions and no marked difference in particle shape the values of k obtained were found to vary appreciably; in some cases by as much as a factor of ten.…”

Control of Particle Size by Coagulation of Novel Condensation Aerosols in Reservoir Chambers

“…3,4 In the latter are processes such as coagulation, evaporation, hygroscopic growth, air entrainment and settling. 5,6 In this paper, coagulation was investigated as a means of controlling the size of CAG aerosols; in this process aerosol particles collide and coalesce to form larger droplets. 7 When this occurs, aerosols show a progressive decrease in number concentration and a simultaneous increase in particle size; the rate and extent coagulation occurs is highly dependent on the aerosol number concentration and the duration of coagulation.…”