COMPUTATIONAL PROBLEMS OF THERMAL RADIATION IN SOLAR ENGINEERING

The assessment of the Darcy–Forchheimer flow of magnetohydrodynamic Williamson nanofluid with entropy optimization is the main purpose of this article. This study was carried out to analyze the impacts on fluid flow via a stratified plate. The impacts of viscous dissipation, chemical reaction, and Joule heating are examined in the existence of nonlinear thermal radiation. The framework of partial differential expressions is transformed into ordinary differential equations by utilizing a suitable set of similarity transformations. The obtained differential equations are analytically tackled by the homotopy analysis approach. -curves, table of convergence, and graphical outcomes are displayed and examined by using MATHEMATICA software. A distinctive parameter chart, against the profiles of temperature, velocity, and concentration with relevant discussion is portrayed for emphasizing their physical importance. Through graphical representations, the Sherwood number, the coefficient of skin friction, local Nussel1t number, and entropy generation impact are examined. This kind of study is useful in many industries like solar engineering, polymer extrusion, electronic supplies, biomedical, etc.

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Characterizing the convective heat exchange with plastic shading nets under natural arid conditions

International Journal of Energy Technology ◽

10.32438//ijet.11415 ◽

2019 ◽

pp. 11-20

Author(s):

Ahmed M Abdel-Ghanya ◽

Ibrahim M Al-Helal

Keyword(s):

Wind Speed ◽

Thermal Radiation ◽

Convective Heat ◽

Convective Heat Transfer Coefficient ◽

Convective Heat Exchange ◽

Radiative Properties ◽

Wooden Frame ◽

Arid Conditions ◽

Air Temperatures ◽

Radiation Fluxes

Plastic nets are extensively used for shading purposes in arid regions such as in the Arabian Peninsula. Quantifying the convection exchange with shading net and understanding the mechanisms (free, mixed and forced) of convection are essential for analyzing energy exchange with shading nets. Unlike solar and thermal radiation, the convective energy, convective heat transfer coefficient and the nature of convection have never been theoretically estimated or experimentally measured for plastic nets under arid conditions. In this study, the convected heat exchanges with different plastic nets were quantified based on an energy balance applied to the nets under outdoor natural conditions. Therefore, each net was tacked onto a wooden frame, fixed horizontally at 1.5-m height over the floor. The downward and upward solar and thermal radiation fluxes were measured below and above each net on sunny days; also the wind speed over the net, and the net and air temperatures were measured, simultaneously. Nets with different porosities, colors and texture structures were used for the study. The short and long wave’s radiative properties of the nets were pre-determined in previous studies to be used. Re and Gr numbers were determined and used to characterize the convection mechanism over each net. The results showed that forced and mixed convection are the dominant modes existing over the nets during most of the day and night times. The nature of convection over nets depends mainly on the wind speed, net-air temperature difference and texture shape of the net rather than its color and its porosity.

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