Y. Agrouaz

Modeling and CFD study of heat transfer within the circulation pipes of solar water heating systems

The main objective of this work is to study numerically the thermal behavior of solar collectors. In particularly, we performed a detailed design and parametric study of the circulation pipe of an evacuated tube collector. Indeed, we altered the geometry of the anodes by adopting three configurations: circular, rectangular and triangular. In each configuration, we changed the inlet position of cold water and the outlet of hot water: either at the top, middle or bottom. The obtained results show that rectangular shape is most optimal due to the large exchange area. On the other hand, the water inlet must be positioned at the bottom and the outlet at the top in order to take profit of the stratification of the hot water and subsequently obtain high efficiency.

Parametric study on the influence of geometrical characteristics of horizontal wavy surface on nusselt number: Solar applications

In this paper a steady-state natural convection was numerically simulated in horizontal rectangular cavity with a sinusoidal bottom wavy wall. This new type of surface rarely studied and investigated. The vertical walls are insulated while the bottom surface maintained to higher temperature than the top surface. In this numerical simulation that based on our elaborated code. the investigated parameters are Rayleigh number that is fixed to Ra=106, the wave length λ varied from 1 to 6 and the amplitude of the wave A is changing from 0.10 to 0.20 with a step of 0.05 were chosen in order to analyze the effect of these parameters on the heat transfer and the flow fields in two dimensional (2-D) enclosure filled with air. It is found that the geometrical parameters has a significant influence on the heat transfer inside the cavity, and also the importance of this study occur in the different applications where this kind of phenomena is present such as cooling, drying systems and solar captors.

Effect of inclined wavy surface on heat transfer inside a rectangular cavity: Solar applications

In this present work a steady-state natural convection was numerically simulated in an inclined rectangular cavity with a sinusoidal bottom wavy wall. The vertical walls are insulated while the bottom surface maintained to higher temperature than the top surface. In this numerical simulation, Rayleigh number (103, 106 and 6×106) and inclination angle (30°, 60° and 90°) were chosen in order to analyze the effect of these parameters on the heat transfer and the flow fields in two dimensional(2-D) enclosure filled in air (Pr=0.71). It is found that the same Rayleigh number, the heat transfer is influenced by the inclination angle. In other words the increase of inclination angle leads to an increase in the heat transfer inside the rectangular cavity.

Heat transfer inside cavities heated by discrete sources: Solar systems

In this paper, we studied numerically laminar natural convection in two types of configurations: the first a square enclosure with four types of discrete sources (Plane, Circular, Square and Triangular) with partial heating of the bottom wall while the rest is maintained constantly adiabatic. The second configuration a rectangular enclosure in which we increased the number of discrete sources for each geometric shape. This study simulates the case of heat generation in a storage tank of hot water or in an electronic component mounting enclosure. The light source is considered to be located in the lower wall with a heated fixed width. This heating will be introduced either as an isothermal or uniform flow. For the purposes of this analysis, the length of the source is set at 20% of the total length of the lower wall. The upper wall, the unheated portion of the bottom wall, the right and left walls will be considered adiabatic. For all configurations the Rayleigh number was fixed at 106. The streamlines and isotherms are presented for various combinations of forms of the heated zone. The results will also be presented in a number of local Nusselt on heated wall.