This paper deals with a numerical study of mixed convection heat transfer in horizontal eccentric annulus. The inner cylinder is supposed hot and rotating, however the outer one is kept cold and motionless. The numerical problem was solved using COMSOL Multiphysics® which is based on finite element method. The resolution of the partial differential equations was conducted through an implicit scheme with the use of the damped Newton’s method. The present numerical analysis concerns the effect of eccentricity, rotation speed and Rayleigh number on the flow patterns, heat transfer rate, and energy efficiency of the process. It was found that the heat transfer rate increases with the increase of Rayleigh number. In addition, the heat transfer rate drops with the increase of rotation speed. Finally, we have demonstrated that maximum energy efficiency is achieved not only with higher Rayleigh number but also it is maximum with small eccentricity.

The objective of this paper is to improve the design of an even-span greenhouse by analyzing the effect of some climatic and design parameters on its performance of drying Olive Mill wastewater. A mathematical model describing the coupled heat and mass transfers inside the dryer was developed and simulated under different condition using COMSOL Multiphysics. An analysis of the dryer performance was conducted in terms of the obtained overall drying efficiency. The findings indicated that the use of a shallow and large pond dyer under hot climatic conditions can improve significantly the drying process. The dryer high and the extension added to the configuration had not achieved any enhancement to the drying efficiency, but can affect the calculations time and installation cost. The developed model was thus used as an effective tool to optimize the drying process.