Browsing by Author "REHOUMA, Ferhat"

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    EXPRIMENTAL AND ANALYTICAL STUDY OF A PARABOLIC SOLAR CONCENTRATOR IN EL OUED CITY
    (University of Eloued جامعة الوادي, 2018-02-05) BOURAS, L; REHOUMA, Ferhat
    This study is focused on the parabolic solar concentrator, called the collector as well as the solar dish. The work is divided into two parts: Firstly, analytical analysis was done to study the effect of the geometrical and optical parameters on the spot focal. Secondly, to design a mini-prototype reflector with 63cm diameter, 6.2cm height, an aperture area of 1.24 m2and focal distance of 42 cm, the reflector surface was covered by silver chrome film. The cylindrical receiver is made of aluminium with 8.5cm diameter and 15cm length. The obtained results showed a significant increase in the temperature of the optical spot ranging from 200 to a maximum value of 850 °C. The distribution of the temperature on the receiver surface area showed clearly that the flux intensity increases gradually and a peak at the focus.
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    Numerical comparative study of Nd: YAG solar laser power in end-pumping and sidepumping configurations
    (University of Eloued جامعة الوادي, 2018-02-05) MEHELLOU, Saïd; REHOUMA, Ferhat
    Solar-pumped solid-state lasers are promising for many applications. Since the report of the first sun-pumped solid-state laser, several pumping schemes have been proposed for enhancing the solar laser performance. Although the most efficient laser systems have end-pumping approaches, side-pumping configurations are very suitable for laser power scaling. Here we report numerical comparisons between the performances of Nd: YAG solar lasers by using either end-pumping or side-pumping techniques. In end-pumping configuration, a conical-shaped fused silica light-guide with 3D-CPC output end is used to transmit, compress the concentrated solar radiation from the focal zone of the parabolic mirror into a 4 mm diameter, 30 mm length Nd: YAG rod, within a conical pump cavity, which enables the multi-pass pumping through the laser rod. In side-pumping configuration, a fused silica light-guide with rectangular cross-section is used to collect nearly the same concentrated solar power from the focal zone. The guide also acts as a beam homogenizer by transforming the near-Gaussian profile of the concentrated light spot, incident on its input face, into a uniform rectangular light distribution at its output end. A 2D-CPC cavity is employed in this approach to enhance both the absorbed pump power and distribution along a 4 mm diameter, 30 mm length Nd: YAG rod. Uniform absorption along the rod is achieved, reducing the thermal loading problems. For 900W/m2 solar irradiance, the maximum solar laser power of 60 W is calculated for the end-pumping configuration, corresponding to 40 % enhancement over the collection efficiency of side pumping configuration.