A MODEL FOR MASS AND HEAT-TRANSFER IN AN AEROSOL CLOUD

In mathematical models for heavy gas clouds dispersing in the atmosphere, two-phase dynamics is usually modelled using assumptions of homogeneous equilibrium. This implies that the mixture of liquid droplets and gas is homogeneous and in thermodynamic equilibrium at all times. This paper discusses a more rigorous approach for modelling the thermodynamical aspects of heavy gas dispersion. A model is presented for the evaporation and condensational growth of a monodisperse binary droplet population, including also the influence of air entrainment. The model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets and a three-component gas. The model has been applied for evaluating two-phase ammonia clouds released in both dry and moist air. The numerical results show the influence on contaminant concentration of the droplet size, the atmospheric moisture and the non-ideality of a liquid solution.