No abstract

No abstract

No abstract

In this study, the turbulent buoyancy driven fluid flow and heat transfer in a differentially heated rectangular enclosure filled with water is quantified numerically. The two dimensional governing differential equations are discretized using the finite volume method. SIMPLE algorithm is employed to obtain stabilized solution for high Rayleigh numbers by a computational code written in FORTRAN language. A parametric study is undertaken and the effect of Rayleigh numbers (1010 to 1014), the aspect ratio (30, 40 and 50), and the tilt angle (10o to 170o ) on fluid flow and heat transfer are investigated. The results of the adopted model in the present work is compared with previously published results and a qualitative agreement and a good validation is obtained. Results show that the fluid circulation and temperature fields are strongly affected by the enclosure tilt angle and Rayleigh Number.

The evaluation of flat shallow cavity solar collector inserted with porous substrate was investigated experimentally and numerically. The aim of this work is to improve the thermal performance of flat plate solar collectors using enhanced heat transfer technique. Porous media were made of multilayer of aluminum mesh to form a porous layer of thickness 25 mm inserted under the absorber plate with porosity of 0.9 and permeability of 84.87.  The solar collector was installed in Baghdad south facing at a fixed tilt angle (45°). Three types of solar collector have been designed and constructed namely solar collector made of shallow enclosure (model I), solar collector made of shallow enclosure inserted partially with porous layer (model II) and solar collector with channels of corrugated channels inserted partially with porous layer (model III). The results of parametric study of model III in case of continuous operating showed that the maximum average water temperature difference of water between collector outlet and inlet exceeds (7.21°C) and the maximum outlet temperature exceeds (50°C) at solar noon for (November, and December 2013). The thermal efficiency for collector model III was ranged from 47.52% to 52.2%, while that for model I was ranged (33.5% to 42.3%) under the same environmental conditions.