Open Access Original Research Article

Heat and Mass Transfer Effects on Unsteady MHD Fluid Embedded in Inclined Darcy-Forchemmer Porous Media with Viscous Dissipation and Chemical Reaction

S. A. Amoo, G. Ajileye, A. O. Amoo

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2018/41870

The Darcy-Forchemmer in fluid-saturated porous media finds application in a variety of engineering processes such as heat exchanger devices, chemical catalytic reactors and metallurgical applications-hot rolling of wires, drawing of metals and plastic extrusion. Also, entrepreneurial development helps in developing MHD power generation systems. The study therefore, investigated unsteady nonlinear MHD fluid embedded in an inclined Darcy-Forchemmer in an inclined porous media. The governing partial differential equations of the model are reduced to a system of coupled nonlinear ordinary differential equations by applying similarity variables and solved numerically using shooting with fourth-order Runge-Kutta method. The local similarity solutions for different values of the physical parameters were presented for velocity, temperature and concentration. The results for Skin friction, Nusselt and Sherwood numbers were presented and discussed. The study included MHD fluid mechanisms in this presentation to justify advance in scientific research and the need for computational analysis and applications.  The study reported the effects of unsteady MHD fluid flow in Darcy-Forchemmer in porous media and its implication as gateway to entrepreneurial development and National growth.

Open Access Original Research Article

An Elastic-plastic Finite Element Analysis of Two Interfering Hemispheres Sliding in Frictionless Contact

Itzhak Green

Physical Science International Journal, Page 1-34
DOI: 10.9734/PSIJ/2018/42783

A vast amount of previous work on hemispherical contact is almost solely dedicated to quasi-static normal loading (axisymmetric 2D models). Some scarce work exists on tangential loading but it is limited to full stick conditions. The sliding of interfering bodies is considerably distinct. Hence, the objective of this work is to investigate two hemispheres sliding across each other, subject to an interference that is large enough to deform their surfaces permanently, during and after contact. Similar (steel-on-steel) and dissimilar (aluminum-on-copper) materials are investigated using a 3D finite element analysis (FEA). The behavior and outcomes are vastly different from previously reported work. Results include the formation and propagation of the von Mises stresses, the deformations, the contact areas, and the energy loss even with friction being absent.  The results are normalized so that they may be applied to any scale (from macro to micro contacts); the main intention, however, is to apply the results to interfering asperities in rough surfaces that are sliding. The effectiveness of that normalization is discussed. Empirical equations for the net energy loss, the permanent residual deformations (damage), and the effective coefficient of friction (in frictionless sliding) are given as functions of the interference. Lastly, some FEA results are favorably compared to those obtained from a semi-analytical method, but these are only limited to a few special cases that the latter is able to solve.

Open Access Original Research Article

Quantification of Total Suspended Particulate (TSP) and its Elemental Content in Different Micro Environments of a Residential Area in Lagos State, Nigeria

J. M. Okuo, F. O. Oyibo, B. Anegbe, I. E. Chiedu, O. Adeniyi, W. Ojo

Physical Science International Journal, Page 1-18
DOI: 10.9734/PSIJ/2018/43109

The need for comprehensive periodic air quality measurements to assess the extent of airborne particulate matter and trace metals exposure in residential areas in Lagos State in view of the urbanization and different energy cooking source cannot be overemphasized. Total Suspended Particulates (TSP) was collected from July 2016 to April 2017 by gravimetric sampling technique in different indoor-outdoor micro environments of a residential area in Lagos and was analyzed by Atomic Absorption Spectroscopic (AAS) method. High base-line concentrations were obtained with an indoor range of 833.33-1944.45 µgm-3 and outdoor range of 1111.11-1944.45 µgm-3 during the wet season. During the dry season, it ranged from 1111.11-2777.78 µgm-3 in the indoors and 1388.89-2222.22 µgm-3 in the outdoors. Elemental concentrations were subjected to enrichment factor analysis (EF) and principal component analysis (PCA) for source identification. EF analysis was used to assess the relative contributions of natural and anthropogenic metals inputs to the air in the area while, PCA identified road dust, combustion activities and marine as the predominant sources of pollutants emission to the environment. To further elucidate the relationship among pollutants in the sampling sites, correlations analysis, cluster analysis and analysis of variance (ANOVA) were carried out. The results of the correlations analysis and cluster analysis confirmed the results of the EF and PCA. The results of ANOVA showed that, there was no spatial variation in the elemental concentration of most of the metals (P>0.05).

Conclusively, results obtained showed that, pollutants concentration in most of the sites were higher than safe limits proposed by regulatory limits.

Open Access Original Research Article

Investigation of the Optical and Electrical Properties of Copper Telluride and Cadmium Telluride Thin Films Using Electrodeposition Technique

Ikhioya Imosobomeh Lucky, P. O. Orji, Osolobri B. Uyoyou, Ijabor, B. Okeoghene, P. N. Okanigbuan

Physical Science International Journal, Page 1-9
DOI: 10.9734/PSIJ/2018/43238

Copper and Cadmium Telluride thin films have been successfully deposited on a glass substrate indium doped Tin oxide (ITO) by electrodeposition technique. The absorbance was measured using M501 UV-visible spectrophotometer in the wavelength range of 300-900 nm. Copper and Cadmium Telluride thin films were investigated at room temperature. The absorbance of cadmium telluride thin films of sample CdTe2 and CdT3 increase with the wavelength while sample CdTe1, CdT4 and CdT5 partially increase as the wavelength increases. The transmittance spectra of the cadmium telluride thin films deposited increases with the wavelength. The absorbance of copper telluride thin films were found to be in the range of 0.152-0.334 for sample CT1, 0.064-0.254 for sample CT2, 0.065-0.257 for sample CT3, 0.049-0.272 for sample CT4 and 0.009-0.220 for sample CT5. Absorbance of copper telluride films is high in the UV region and in visible and IR regions. The transmission spectrum has a very high transmittance in the VIS-NIR regions of the electromagnetic spectrum. It is also observed that the transmittance of the films is high in visible & infrared regions. The band gap energy of (2.0eV-2.2eV for CT) and (2.2eV-2.5 for CdT) was obtained.

Open Access Original Research Article

Degradation of Crystalline Silicon Photovoltaic Cells/Modules under Heat and Temperature Effect

Géraud Florentin Hounkpatin, Basile Bruno Kounouhéwa, Macaire Agbomahéna, Vianou Irénée Madogni

Physical Science International Journal, Page 1-12
DOI: 10.9734/PSIJ/2018/42864

Temperature is extremely significant to the PV modules degradation process, especially hot spots, encapsulant bleaching, delamination failure on interconnections, corrosion, discoloration, and bubbles on the panel’s surface. 

We investigated the degradation of crystalline silicon PV cells/modules exposed under heat and temperature effect.

We established a qualitative correlation between the electrical parameters affected and the different modes of PV cells/modules degradation.

We reveal that: the leakage current increase rapidly with increasing number of hot spots. The effect of discoloration causes loss of transmittance of the encapsulant EVA, and reduces the photocurrent density (Jph) owing to a decrease of absorption, and therefore the power loss. Discoloration does not affect the fill factor (FF) and (Voc) more, but the corrosion causes a decrease of the PV modules maximal power (Pmax) when the delamination of the PV module reduces the thermal conductivity locally and hence increases the temperature of the cell.    

Delamination, bubbles, corrosion, hot pots, EVA discoloration are the predominant modes of the PV cells/ modules degradation.