College of Engineering, The University of Utah

Dynamic Modeling of Atmospheric Aerosols


Current research is also focused on the dynamics of the evolution of aerosols. It consists in two main streams.

First Part : Modeling the Multicomponent Aerosol Dynamics



The detailed dynamic modeling of multicomponent aerosol particles is complicated by a variety of factors, including a complex set of ionic and non-ionic species formed in the system, complex thermodynamics, simultaneous phase and reaction equilibria, and the appearance and disappearance of thermodynamic phases depending on atmospheric conditions.
Over the last decade, a number of aerosol dynamic models have been developed. Although these models apply fundamental mass transfer equations to liquid aerosol particles, they employ significant simplifications in their representation of solid particles. They may also encounter difficulties with transitions between solid and liquid phases as well as between neutral and acidic states.
Recently, we have developed efficient computational methods that can adequately describe the dynamics of an aqueous electrolytic system involving one vapor, one aqueous and multiple solid phases. This algorithm is based on the active-set method to model the phase appearance and disappearance. The overall model can be expressed as a mixed set of differential and algebraic equations of index 1. The algorithm is implemented in UHAERO module 3, a general dynamic model that predicts efficiently the aerosol deliquescence, crystallization, solid to solid phase transitions, and acidity transitions. In this study, our goal is to develop a general multicomponent aerosol dynamics model that is capable of solving the condensation/evaporation equations of atmospheric mixed organic and inorganic aerosols.

Second Part : Modeling the Deliquescence and Efflorescence Hysteresis


For atmospheric aerosols, the particle phase behavior is accurately described by the thermodynamic phase diagrams during deliquescence. However, for efflorescence, a kinetic barrier must usually be overcome. The deliquescence behavior of some common inorganic salt components of individual and mixed aerosols such as NaCl, Na2SO4, (NH4)2SO4, and NH4NO3 have been studied extensively using numerous techniques. Only a few studies, however, have been carried out on the deliquescence behavior of multicomponent inorganic aerosols. Given the impacts of particle phase on atmospheric chemistry and the radiation balance, modeling the deliquescence and efflorescence behavior of mixed atmospheric particles is clearly essential to predicting their roles in the atmosphere. Recently, we have developed a computational method for the micro-physically consistent treatment of deliquescence/efflorescence hysteresis effects of inorganic aerosols. Our model is based on classical homogeneous and heterogeneous nucleation theory. Combined with state-of-the-art laboratory data and models of surface tension, our kinetic model can be applied to simulate the induced crystallizations and other hysteretic hygroscopic responses of atmospheric particles containing water-insoluble components such as mineral dusts. In this study, our goal is to develop a general multicomponent dynamics model that is capable of simulating the deliquescence and efflorescence behavior of atmospheric mixed organic and inorganic aerosols.


The UHAERO dynamics module will be available [here] in a near future.


http://www.tlc2.uh.edu/uhaero/Research/Project3/index_html
© College of Engineering, The University of Utah