An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were built-in clay bricks in order to study their influence on the compressive strength, Young's modulus and the speed for soundproofing. Testings in compressive strength were made on the parallelepiped clay bricks, stabilized with different percentages of cement, with incorporation to various percentages of sawdust or wood chips (Mahogany), using a universal press. Young's modulus was measured from the speed of sound by the ultrasonic method. The results obtained show that the incorporation of mahogany tree chips in the stabilized brick at 8% of cement, does not have much effect on the compressive strength. It was found that the incorporation of chips or sawdust on the clay brick, does not improve the compressive strength. The Young's modulus decreases with increasing content of sawdust and practically remains constant regardless of the content of chips at 4% and 6% of cement. The clay brick mixed with 8% of mahogany sawdust can be an acoustic barrier.
To take into account the variation of the recombination velocity at the grain boundaries, we present in this paper a new approach of characterization of the solar cells, based on the two dimensional finite element method. The results of this study on a bifacial polycrystalline silicon solar cell, modelled in the rectangular form, highlighting the effects of the boundary recombination velocity (S gb) on the solar cell electrical parameters. The photogenerated excess carrier's density, the photocurrent density; the phototovoltage and the current-voltage characteristics are analyzed, namely. A good agreement with the results given in the literature is observed.
Abstract-In this paper, we present results of characterization of a bifacial silicon solar cell, under multispectral steady state illumination, using finite element method (FEM). The illumination level (n) and back surface recombination velocities (Sb) effects on solar cell electrical parameters have been highlighted. After solving the continuity equation that describes the solar cell operation, the excess minority carrier's density and current-voltage characteristics are determined for various values of illumination level and recombination velocities on the junction and the back surface of the solar cell. The results obtained are in agreement with those given by analytical methods and prove that the photovoltaic cells can be analyzed only by numerical methods, such as the FEM, characterized by their robustness and flexibility in their applications in a context where those methods take more and more importance in the development of Computer Aided Design (CAD) tools.
The use of the Peltier effect for the cooling of a cooler powered by photovoltaic energy is a solution for the conservation of foodstuffs or pharmaceuticals when conditions as well geographical and climatic become difficult. Only a problem often arises with the choice of the supply current. Indeed, a choice of the supply current too low will produce less cold while a choice of too much supply current (very close to the maximum value indicated by the manufacturer of the module) will produce more cold, but the module will work in saturation, which will reduce its life. This article proposes to present the possibility of optimizing a thermoelectric refrigeration installation. In particular: by improving the performances of the installation, by maximizing the coefficient of performance and the cooling capacity as a function of the power supply current of the Peltier effect module (of the TEC1-12706 type). Thus, to solve this problem, we propose an optimization of the thermoelectric installation while passing by the method of the derivatives which will make it possible to find this optimal current. This optimal current will be average current corresponding to the performance coefficient and the current for which the refrigeration power becomes maximum.
In this paper we present a technique for determining the optimum junction recombination velocity of a solar cell, using a combination of the electrical equivalent model, and the finite element method. Starting from the continuity equation that describes the solar cell operation solved in one dimension by the finite element method, the excess minority carrier's density is determined. From this density, the photocurrent, the photovoltage and the power produced by the solar cell are determined. The photocurrent and the photovoltage are represented according to the junction recombination velocity, as well as the solar cell power versus the photovoltage, for various values of the series resistance. In considering its equivalent electrical model, the solar cell is modeled and simulated with Matlab/Simulink. In this simulation model, the capacitor initially discharged, charges under the effect of the solar cell. Its impedance varying according to time, represents the load resistance which corresponds to an operating point of the solar cell. During the capacitor charge process for various values of the series resistance, we obtain the current-voltage characteristic of the solar cell in order to highlight the series resistance effects on the solar cell power. From the optimal value of the power, and that of solar cell photovoltage obtained by simulating the solar cell using Matlab/Simulink, the value of the junction recombination velocity corresponding to the maximum value of the solar cell power is determined numerically, for various values of the series resistance.
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