Numerical Study of Heat and Mass Transfer by Laminar and Turbulent Natural Convection With Cross Diffusion Effects in Square Cavity

Author(s):  
Wenguang Geng ◽  
Baoming Chen ◽  
Maocheng Tian ◽  
Fang Liu

Laminar and turbulent natural convection flow in a two-dimensional square cavity filled two component system with compensating horizontal thermal and solute concentration gradients is investigated in this paper. The temperature gradient and volatile organic compounds (VOCs) concentration gradient are kept uniform in horizontal direction, while horizontal surfaces are kept adiabatic and impermeable within a square cavity. According to the principle of irreversible thermodynamics, with thermal-diffusion (Soret) effect and diffusion-thermo (Dufour) effect, a commercial computational fluid dynamics (Fluent) code is used to simulate heat and mass transfer numerically in present work. After validation of the method with available measurements, the range of the cross diffusion coefficients are analyzed firstly. Furthermore, the thermal field and solute concentration fields are presented for various conditions. Finally, the average Nusselt number and Sherwood number at the vertical wall are presented graphically. The numerical results show that the present work would help to know about the convective diffusion and distribution of VOCs indoor environment accurately. Also, it gives the more accurate characteristics of heat and mass transfer in multi-component system with cross diffusion effects.

Author(s):  
Wenguang Geng ◽  
Baoming Chen ◽  
Kai Sun ◽  
Li Wang ◽  
Fang Liu

Natural convective heat and mass transfer with Soret effect and Dufour effect is experimental studied in this paper to investigate the diffusion characteristic of volatile organic compounds (VOCs) in multi-physical fields. Firstly, Soret effect (thermal diffusion effect) experiment is conducted. The transfer process of isobutane and nitrogen in two close container connected by a small-diameter pipe is experimental studied. The results show that temperature difference between the two containers would conduct a solute concentration difference. Furthermore, multi-component convective diffusion experiment in a closed cavity which simulate indoor environment is developed under temperature gradient, humidity and propane gas concentration gradients. In this experiment, Temperature, humidity and concentration of propane could be surveyed real-time and do not interfere the natural convection in the closed cavity. The experiment results show that that the temperature gradient and the water vapor concentration gradient have effects on the convective diffusion of VOCs indoor environment. 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.


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