The objective of this work is the mathematical modelling and the numerical simulation of the stationary, laminar, and natural convection, in a confined square cavity (H = L) filled with two fluids (a mixture of nanoparticles of aluminum oxide and Al2O3 water) in one partition and pure water in the other partition. A porous conductive wall of thickness w (w = L/e) and thermal conductivity Keff constitutes the exchange surface between these two partitions. The fluid movement is modeled by the Navier-Stokes equations in the two partitions, while the porous medium is modelled by the Darcy–Brinkman equation. Comsol Multiphysics software is used to solve the system of differential equations that is based on the finite element method. The results are discussed with particular attention to the mean and local Nusselt number (Nu), streamlines and isotherms. A parametric study for Rayleigh number Ra (102 to 106), volume fraction j (0% to 10%), and Darcy number Da (10-7 to 10-2) is performed. The obtained findings show that the increase in Ra, Da, and j intensifies the flow and improves the thermal exchange on the cold wall. For Da £ 10-5, Nu remains practically low and the natural convection is being dominated by conduction. For Da > 10-5, an increase in Nu is observed and the flows tend towards a purely convective situation. Furthermore, an increase in the heat transfer coefficients is observed with the raise of the porous layer permeability, volume fraction and Rayleigh number.

Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. The critical problem in the a-Si:H-based photovoltaic cell is increasing the conversion efficiency. To overcome the difficulty,  higher conversion efficiency demands a longer optical path  to increase optical absorption. Thus, a light trapping  structure is needed to obtain more efficient absorption. In this context, we propose a complete solar cell structure for which a 1D grating is etched into the ultrathin active absorbing layer of a one-dimensional "CP 1D" photonic crystal a-Si: H characterized by the optimal parameters: period a = 480 nm, a filling factor ff = 50% and a depth d = 150 nm. This was selected by varying the CP1D parameters to maximize the absorption integrated into the active layer. CP1D is suggested as an intermediate layer in the solar cell concentration system. This study allowed us to model the optical and electrical behavior of a CP1D solar cell. After optimization of the geometrical parameters (period and fill factor ... etc.), we concluded that the CP1D led to greater optical gains than for their unstructured equivalent. The simulation clearly illustrates that the electric field strongly affects the electro-optical characteristics of the devices studied, and that it is clear that 1D PC solar cells as active layer have exhibited a high electric field distribution. We have focused on the net on the effect of the active layer and its beneficial role in the sense of expressing the photovoltaic performance of the devices.

In the proposed study, an investigation has been carried out in order to find a material efficient structure, capable of harnessing maximum solar spectrum. A material efficient structure designed using a one dimensional photonic crystal (1D PC) for amorphous silicon. Silicon material is used as it leads to environmental friendly design. The principal objective of this study is to maximize the photon absorption, keeping reflection to a minimum. The influence of geometric parameters on the absorption is studied by using the Finite element method (FEM). The results show that the absorption is affected by the geometry parameters. The optimum parameters of the proposed structure are period (a  480 nm), a filling factor (ff  50 %) and depth (d  150 nm). The increase of absorption in the lower region where the wavelengths are around 480 nm, is explained by the reduction of the effective index resulting from the structure of the absorbent layer. For wavelengths between 480 nm and 600 nm, the absorption is directly related to existing Fabry-Perot modes within the absorbent layer. Creating additional absorption peaks at wavelengths above about 600 nm weakly absorbed normally comes from the coupling of the incident light with slow Bloch modes of PC located above the light line.

In this article, we have shown the possibility of improving the quality of the energy injected into the electrical network and the flexibility of its exchange between the different components of the proposed hybrid network (photovoltaic generator connected to the network-storage battery-load of the DC motor) to develop a control element based on the combination of fuzzy logic and an algorithm derived from PSO Animal Behavior. The proposed control works on DC/AC and bi-directional DC/DC converters, which form the basis of power management between the parts of the proposed hybrid network. MATLAB/Simulink software is used to demonstrate the effectiveness of the proposed control. The results show that the proposed control contributed to the stability of the photovoltaic energy produced, the improvement of the quality of energy injected into the network, as well as the response speed during the process of charging and discharging the battery, which gave more efficiency to the DC motor connected to the DC bus.

Good light trapping is essential to make high efficiency InGaN-based solar cells. As InGaN wafers are being made increasingly, thinner, light trapping becomes even more important. In this study, we propose a structure of one-dimensional InGaN grating for the InGaN-based solar cells is proposed. The solar energy absorption characteristics of this structure are studied by the the Finite element method (FEM) method. By alternately altering the grating depth and the filling factor, a new type of grating structure is proposed. For such a structure, different gratings are studied. Numerical computation shows that the absorptance of the InGaN grating structure is over 0.88 throughout the entire computational band. The optimum parameters of the proposed structure are period (a = 480 nm), a filling factor (ff = 50 %) and depth (d=210 nm), which indicates the proposed structured surface may have potential applications in solar cells manufacturing.