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Abstract This paper is focusing on a numerical investigation of hydrogen Active Magnetic Regenerative Liquefier (AMRL). For this purpose, two-dimensional transient numerical modeling with finite volume method has been developed (i.e. CFD method) to simulate the parallel plane plate (PPP) AMRL regenerators type in order to predict and investigate its thermal performances. The resulting mathematical model has been implanted in ANSYS-Fluent software to overcome the complexity of the Active Magnetic Regenerative (AMR) cycle. To run the simulations, a six cascade-stages hydrogen AMRL cycle has been proposed. From the first to the last stage, the regenerators are made of the following magnetic materials: Gd, Tb, Dy, Ho, Er and Tm respectively. The validity of the proposed model has been performed through Cristal2 AMR demonstrator built to operate at room temperature. Good agreements have been found between experimental and numerical results. Then, simulations of the proposed multistage hydrogen AMRL have been carried out for applied magnetic induction up to 7 T. It has been shown that a mass flow rate of 100 mg s−1 of hydrogen initially at 300 K and 1 atm can be cooled down to 57 K. Thus, the capability of the proposed CFD method for predicting consistent results has been demonstrated.

Abstract The “shell” dryer is an African solar food dryer which uses natural convection. Its design has been defined by users, in terms of local working conditions and ease of use. However, it is necessary to optimize the design of the dryer's air flow section for best performance. We present here a theoretical study of a simple process using mathematical modelling tools.

The necessity for improving the thermal performances of the solar air collector, for some needs, encouraged us to carry out this study. Initially, to improve the efficiency factor of these solar collectors, we create an increasingly turbulent flow between the absorber and the back wooden plate. For that, we use obstacles of various forms. In this study, we chose rectangular plate fins inserted perpendicular to the flow. The fluid flows out through the interstices between fins in the same row, this allows a good distribution of the fluid and reduces the dead zones. Secondly, and for the same configuration, we undertake a study on the evaluation of the transfer coefficient. The results are compared with those obtained with a solar air collector without fins, using two types of absorbers selective (in coppersun) or not selective (black-painted aluminium).

Abstract This work presents and analyses the X-ray diffraction data for the semiconducting compound CuInSe2, synthesized by the vertical Bridgman method. The ( Cu In ) ratio was varied to produce a stoichiometric CuInSe2 ingot. Structure factors (Fhkl) equations for the (hkl) reflections, which are available for the ternary chalcopyrite-structured semiconductors, were deduced analytically and have been used to calculate the relative peak intensities for CuInSe2 diffraction planes. CuInSe2 thin films were also prepared by flash evaporation of a stoichiometric CuInSe2 powder, onto different substrates. Structural characterization of these films was carried out by X-ray diffraction and scanning electron microscopy studies. The composition of the different samples has been determined by energy dispersive spectrometry. The results obtained indicate the presence of the chalcopyrite phase and nearly stoichiometric compositions.

Abstract The purpose of the experiment was to better understand the changes due to thermal transitions and the molecular organizations of EVA encapsulant material after cross linking process by thermal analysis methods as DSC, TSC and DMTA. DSC experiments on EVA show a glass transition at about −33.1 °C, which is characteristic of crystalline phase and an endothermic peak at temperature of 55 °C characteristic of amorphous phase. The basic results by TSC technique is that there are two relaxations that are reproducibly observed in crosslinked EVA encapsulant material. At temperature polarization 60 °C, a low temperature relaxation occurs at temperature −24.4 °C and a high temperature relaxation occurs at temperature +30.4 °C. DMTA results exhibit two tanδ peaks located at −14.9 °C and +66.6 °C. In addition, our results reveal that the glass transition temperature determined by TSC experiments in depolarization mode is more relevant than DSC and DMTA methods. TSC was chosen due to its low equivalent frequency consideration, useful to study encapsulant material exhibiting multiple relaxations.

The purpose of this work is to examine specific features of thermal and photovoltaic solar systems and their contribution to the sustainable tourism development of Mediterranean islands. In doing so, the best practices are studied and the factors which influence the transfer of these practices in other geographic regions are examined. We take under consideration the sensitiveness of many islander Mediterranean regions in relation to the climate changes and the perspective of their economic development through thematic tourism forms and differentiated tourism products and services. At a further step, we present currently developed innovative applications which are specially adapted to the needs identified within this research and we propose marketing strategies for their further expansion. The marketing approach followed is based on an innovative concept, which suggests that solar energy systems could constitute a driver for the development of specific forms of tourism. These systems are mainly the ICS solar water heaters, the coloured flat plate-collectors, the CPC collectors and the hybrid PV/T collectors. Apart from these, the use of booster reflectors that achieve a higher energy output in all cases of the above mentioned collectors is also suggested. We conclude that turning solar energy systems into a driver for specific types of tourism development and consequently of a local economic development is possible, if we take into consideration specific social needs and aspirations.