Double-diffusive natural convection in a solar distiller with external fluid stream cooling

• DOI: 10.1016/j.ijmecsci.2020.105728
• Publication Date: 2020-05-15T20:38:09Z
• Authors: Khalid B. Saleem; Lounes Koufi; Ahmed K. Alshara; Lioua Kolsi
• Keywords: Sherwood number; Lewis number; Schmidt number

Abstract Numerical results of laminar double-diffusive natural convection in a trapezoidal shape solar distiller occupied with an air-vapor mixture are carried out. In the present paper, the distiller is subjected to cooling fluid with a cold free stream temperature from the upper wall that kept at low concentration. The lower distiller wall kept with hot temperature and high concentration. The finite volume method based on SIMPLE algorithm is employed to solve the governing equations. Outcomes are performed with a scope of Rayleigh number (104 ≤ Ra ≤ 106), free stream Reynolds number (102 ≤ Re∞ ≤ 105), buoyancy ratio (N = 1, 2,5 and 10) and varying cooling fluid (air or water). The Prandtl (Pr), Schmidt (Sc) and Lewis (Le) numbers are fixed at 0.7, 0.62 and 0.89, respectively. The results revealed a considerable enhancement on the mass and heat transfer rates with increasing of Ra, N and Re∞. The effect of Re∞ is more pronounced with Ra = 106. On the other hand, more vortices formed in the cavity as Ra and N augments and the maximum vortices number obtained when N = 5. Regarding the local Nusselt (NuL) and Sherwood (ShL) numbers, improvements are found both on the upper and lower cavity walls as Ra and N rise. The impact of N on NuL and ShL turns out significant with the higher value (N = 10).