Numerical Modeling and Parametric Study of a Wet Air Flow Between Parallel Plates
Ana Carolina O. de Paula1; Kamal A. R. Ismail1
1 UNICAMP
doi:10.20906/CPS/CILAMCE2017-0643
Resumo
Many engineering applications involve not only fluid motion due to temperature difference, but also due to gradients of other scalar quantities. This phenomenon is called binary natural convection and occurs in refrigeration towers, pollutants dispersion applications, and even desalination through distillation. In this context, the present paper investigates numerically heat transfer and fluid flow by binary natural convection in a cavity filled with air and water vapor, and analyzes the effects of varying inclination and aspect ratio on Nusselt number and condensation rate. The cavity contains two horizontal plates subject to different temperature and concentration. The vertical walls are adiabatic. Water vapor is considered at saturated state. The governing equations for this problem are conservation of mass, energy, momentum and concentration, and these equations are discretized through the finite volume method and organized in an algorithm. The conservation equations are coupled, and their solutions are based on the algorithm SIMPLE. The velocity, temperature and concentration fields are obtained for a Rayleigh number range where laminar flow prevails, and for different cavity inclination angle and aspect ratio. Results show that Nusselt number and condensation rate at the cold wall tend to increase as Rayleigh number and cavity inclination increases. However, for low aspect ratios, Nusselt number decreases and condensation rate at the cold wall increases. For higher Rayleigh numbers, the thickness of concentration and temperature boundary layers decreases leading to a homogeneous mixture in the central region of the cavity. Considering these results, a cavity of good performance has 40 degrees inclination and aspect ratio of 1/12.
Palavras-chave: Binary natural convection; Finite Volume Method; Algorithm SIMPLE; Inclined cavity; Condensation rate