Numerical Study of Natural Convective Diffusion of VOCs With Soret and Dufour Effects in Ternary-Component System

The effect of cross diffusion namely Soret effect and Dufour effect on the convective diffusion of volatile organic compounds (VOCs) indoor environment is investigated in this paper. Based on the principle of thermodynamics of irreversible processes, a mathematical model is developed for the ternary component system (VOCs, dry air and water vapor) with compensating thermal and solute gradients, and this mathematical model is solved numerically by commercial CFD (Fluent) code. Profiles of the dimensionless velocity, temperature and concentration are shown graphically with Soret and Dufour coefficients. Furthermore, the cross diffusion effects on the mass transfer induced by two different solute (VOCs and water vapor) concentration gradients is numerical studied. Finally, numerical values of physical quantities, such as the average Nusselt number and Sherwood number are presented. The numerical results show that the temperature gradient and the water vapor concentration gradient have an effect on the convective diffusion of VOCs indoor environment, and the cross diffusion effects would be taken into consideration for the problem of simultaneous heat and mass transfer especially in the presence of large temperature and concentration gradients.