NUMERICAL-STUDIES ON THE BEHAVIOR OF AEROSOLS IN SMOG CHAMBERS

A physical and chemical model to describe the formation and the behaviour of aerosols in smog chamber experiments is essential if such experiments are to be evaluated. On the basis of already existing computer models for simulating the aerosol behaviour during accidents in nuclear power plants, a model was developed, including nucleation of sulfuric acid and water vapour, condensation of sulfuric acid on particles, heterogeneous reaction on the particle surface and, of course, the aerosol-physical processes of coagulation, sedimentation and diffusion to the walls. The last effect turned out to be very important for such experiments due to the high mobility of the small nuclei. In developing the model, intensive studies on the data base were performed and are presented together with several comparisons between model calculations and experiments. The comparisons with the experiments showed that one of the crucial points is the exact definition of the thermodynamic conditions in the chamber. Otherwise conclusions drawn from the experiments might be incorrect and misleading.