AEROSOL FORMATION IN PHOTOCHEMICAL SMOG

During operation of smog chambers, the gas mixture is normally well-stirred although the extent of stirring varies from chamber to chamber. Experiments conducted at Battelle’s Columbus Laboratories in a 200-liter and a 610-cu ft smog chamber have shown that stirring can decrease aerosol formation. The faster the chamber contents are stirred the greater the reduction in aerosol formation observed. Sufficiently rapid stirring can completely prevent observation of aerosol formation by light scattering. However, thermal gradients in these chambers have been adequate to maintain homogeneity after initial mixing and satisfactory chamber experiments are being performed by turning the stirring off prior to turning on the lights. The differences in aerosol formation between stirred and nonstirred chamber operation is dependent on the type of system being studied and the stirring rate. In the 200-liter chamber during dynamic operation (4-hour average residence time) aerosol formation from 1-heptene/NOx and l,3,5-tr...