Solar energy is a renewable type, clean, and inexhaustible which is sufficiently available on the Algerian territory. The energy received daily on a horizontal surface of 1 m2 is in the order of 5 kWh over almost the whole Algerian territory; the duration of sunshine surpasses 2000 hours annually and can reach 3900 hours on the highlands and the Sahara. The importance of this work is based on exploiting solar energy to produce electricity. This study is based on the experimental exploitation of solar energy using solar tree’s prototype suggestion. This new model is focused to replace the leaf of a tree by the solar cell, starting by examining the solar field and physical phenomenon related with it; the description of cell photovoltaic comes after; and finally, the dimension of the solar system and the experimental studies are virtually released in the University of M’sila. In this work, a prototype of new artificial solar tree is proposed experimentally by using material available in the local market: 25 solar panels, metal support, electrical queues, regulator, and battery. The results highlight a power improvement in the case of the proposed new model (solar tree) compared to the traditional one provided (solar panel), for the specified time range between 8 am and 2:30 pm. On the other hand, the traditional model values improve if the time dimension is extended from 2:30 pm to 6:00 pm. This is due to the temperature of the region and the presence of interstellar spaces between the cells of the solar tree.

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A solar polymer heat exchanger is designed to heat water; its primary materials are plastic water bottles with a capacity of 1.5 liters. These materials were recycled to preserve the environment and to make use of it again. The thermal insulation properties are adopted for the characterization of polymeric materials. These properties concern the conservation of energy for the longest period of time and the absence of problems caused by rust and corrosion, which are usually encountered in traditional heat exchangers. The heat exchanger experiments start by tracking the flow of water inside the pipes by a valve. The water temperature and flow rates are determined at the inlet and outlet surfaces of the exchanger. The obtained results indicated an increase in water temperature exceeding 10℃ in an ideal spring day. The thermal efficiency of the solar collector was about 62% under the sunlight, and 44% in the laboratory where halogen lamps were used as an industrial light source.

Numerical simulations aim to investigate the bifurcation caused by swirling flow between two coaxial vertical cylinders, and the fluid layers produced by the thermal gradient. The stability of both bifurcation and fluid layers by an axial magnetic field is analyzed. The finite-volume method is used to solve the governing Navier–Stokes, temperature and potential equations. A conducting viscous fluid characterized by a small Prandtl number [Formula: see text] is placed in the gap between two coaxial cylinders. The combination of aspect ratio, [Formula: see text] and Reynolds number, [Formula: see text] for three annular gaps ([Formula: see text] and [Formula: see text]) is compared in terms of flow stability, and heat transfer rates. Without a magnetic field, the vortex breakdown takes place near the inner cylinder due to the increased pumping action of the Ekman boundary layer. Fluid layered structures are developed by the competition between buoyancy and viscous forces. The increase in the magnitude of the magnetic field retarders the onset of the oscillatory instability caused by the disappearance of the vortex breakdown and reduces the number of fluid layers. The limits in which a vortex breakdown bubble manifests and the limits of transition from the multiple fluid layers to the single fluid layer are established.

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The hydrothermal behavior of air inside a solar channel heat exchanger equipped with various shaped ribs is analyzed numerically. The bottom wall of the exchanger is kept adiabatic, while a constant value of the temperature is set at the upper wall. The duct is equipped with a flat rectangular fin on the upper wall and an upstream V-shaped baffle on the lower wall. Furthermore, five hot wall-attached rib shapes are considered: trapezoidal, square, triangular pointing upstream (type I), triangular pointing downstream (type II), and equilateral-triangular (type III) cross sections. Effects of the flow rates are also inspected for various Reynolds numbers in the turbulent regime (1.2 × 10 4 -3.2 × 10 4 ). The highest performance (η) value is given for the II-triangular rib case in all Re values, while the square-shaped ribs show a significant decrease in the η along the achieved Re range. The η value at Re max is 2.567 for the II-triangular roughness case. Compared with the other simulated cases, this performance is decreased by about 3.768% in the case of I-triangular ribs, 15.249% in the case of III-triangular ribs, 20.802% in the case of trapezoidal ribs, while 27.541% in the case of square ribs, at the same Re max . Also, a comparison is made with air-heat exchangers that have non-rough walls and contain cross-shaped VGs presented previously, in order to highlight the effectiveness of the rough surface presence in the baffled and finned channels. The obtained results indicated that the triangular-shaped rib (type II) has the most significant hydrothermal behavior than the other cases. This indicates the necessity of roughness heat transfer surfaces for finned and baffled channels to improve significantly the performance of the air-heat exchangers they contain.

Solar distillation is a very economical process for the fresh water production, especially in arid and semi-arid areas where solar energy is abundant. Several types of solar stills have been designed and manufactured for a purpose to increase their performances. This work aims to study experimentally under outdoor conditions of Hodna’s region, two types of solar still, the first is an inclined solar still with different wick thicknesses (thick, medium and thin) operating in drop by drop system of feed water and the other is conventional. Four clear days of the April months have been chosen to experiment the solar stills performances. The results showed that the solar stills performances are notably influenced by design and operating conditions, as revealed by the daily production and efficiency values of the inclined solar still with thin wick which achieved 4.14 liter/m2.day and 46.66%, with an improvement of about 23.21% and 12.56 % respectively, compared to those of the conventional solar still, which reached 3.36 l/m2 and 34.1% respectively. In addition, the economic analysis illustrates that the low cost of one liter of distilled water and the quicker payback period at the same time are for the inclined solar still with a thin wick of about 0.011$/l and 77 days respectively.

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