The shock tube technique applied to study aerosol rate processes

Aerosols are gas-particle suspensions characterized by two features: the size of the particles is very small and the volume fraction of the particle phase is extremely low. Aerosols can undergo different rate processes causing changes of the particle and/or of the gas properties. In the present case a shock tube is used as an isothermal-isobaric reactor, in which aerosol rate processes can be started by the step-like temperature and the fluid velocity increase. Examples are heterogeneous oxidation reactions at the surface of carbonaceous particles, evaporation of solid or liquid aerosol particles, or fluid flow induced disintegration of agglomerated solid primary particles. All these aerosol rate processes were studied behind shock waves in the form of relaxation processes. Rate parameters were determined from light scattering or spectroscopic measurements as will be shown in the paper.