Adnane Labed

Performance investigation of single- and double-pass solar air heaters through the use of various fin geometries

This paper presents an experimental comparative study on the thermal performance of the following three single-pass types of solar air heaters (SAHs): (i) without obstacles, (ii) with rectangular obstacles and (iii) with a new form of obstacles in the air flow duct. Thus, we carried out studies to compare the best system with (iiii) a double-pass flat plate collector having the same type of obstacles in order to determine the best-performing model. All collectors were designed, constructed and tested in the University of Biskra (Algeria) in a stand facing South at an inclination angle equal to the local latitude. In comparison with the recent literature, at different air mass flows, the highest efficiencies were obtained from the double-pass SAH with trapezoidal obstacles. In addition, this study has allowed us to show that the use of obstacles, in the air flow duct of the SAHs, is an efficient method to improve their performances.

Experimental investigation of various designs of solar flat plate collectors: Application for the drying of green chili

This paper presents an experimental study by comparing between the thermal performance of three types of solar air flat plate collectors, FPCs: (i) without obstacles, (ii) with rectangular obstacles, and (iii) with trapezoidal obstacles in the air flow duct. In order to determine the best performing model, we have proceeded to reversing the flow direction, in each collector, and comparing the six obtained models under outdoor conditions. All collectors were designed, constructed, and tested in the University of Biskra (Algeria) in a stand facing south at an inclination angle equal to the local latitude. Thus, we have proceeded to the application of the best system for the drying of the green chili. We have sought to determine the moisture content and loss of mass for the forced convection hot air drying of the product and their temperature dependence. In comparison with the recent literature, at different air mass flow, the highest efficiencies (77%) were obtained from the FPC with trapezoidal obstacles, ...

Effect of Different Parameters on the Solar Drying of Henna; Experimental Investigation in the Region of Biskra (Algeria)

This paper presents the results of an experimental investigation on the thermal performances of two models of solar air flat-plate collectors (FPCs) for drying applications (indirect dryers). We carried out studies in order to determine the best-performing model and to achieve a clean product in the least possible time by using a sustainable energy. Thus, we have proceeded to the application of the best-performing dryer for the drying of the henna (Lawsonia inermis); we have sought to determine the influence of some parameters on the drying kinetic of the product for the forced convection hot-air drying and their temperature dependence. The drying air was heated by solar energy under variable outdoor conditions. Both collectors were designed, constructed, and tested in the University of Biskra (Algeria) on a stand facing south at an inclination angle equal to the local latitude.

Multiple solutions for free convection flow in inclined enclosures

In this paper, we investigated the free convection flow in inclined rectangular enclosures filled with air. The analysis is carried out by a numerical solution of the full governing equations of the problem employing the finite volumes approach with staggered grid arrangement by the iterative SIMPLE-C algorithm. We propose for three aspect ratios AR = 3, 4 and 8 a parametric description illustrated the influence of the inclination angles 0° ≤ φ ≤ 90° and Rayleigh number 103 ≤ Ra ≤ 104, on the flow patterns likely to develop in each configuration. The results indicate that the effects of inclination on flow mode transition and multiplicity of solutions for each aspect ratio at various Rayleigh numbers, the existence of such multi-steady solutions strongly depends on the value of the Rayleigh number. For that the Hysteresis phenomenon for Ra ≥ 2000 are demonstrated and also the parameter maps of Ra vs φ are constructed.