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This paper presents an empirical investigation of the melting processes of phase change material (PCM) in a tube and shell heating exchanger utilizing solar thermal energy. The experiments were conducted outdoors in Al-Mussaib city, Babylon, Iraq (Lat 32.5° North, long 44.3° East), utilizing a north-south (N-S) collector oriented at a tilt angle of 32.5° from the horizontal. This work utilized pure Iraqi black paraffin with 12 kg as PCM. The main empirical rig involves a vacuum tube solar collector (VTSC) utilizing a tube and shell heating exchanger to melt PCM in the shell regime. Different rates of water flow inside the internal heating exchanger's tube, namely (3.5, 5, and 8.5 L/m), were utilized for each season from August 2022 to January 2023. The empirical findings concluded that the internal tube inlet and surrounding temps significantly influence the melting process compared to the rates of water flow. It was found that the melting process of PCM needs about (3 to 4) hours in the summer season. Still, winter needs a longer time, about 14 to 16 hours. Increasing surrounding temp and solar radiation reduces the melting time of phase-change material. The findings of the present work were compared with the earlier investigations and agree with increasing the present work by 23.5 %. The findings from the present study are of practical importance for industries requiring storage materials to improve thermal storage system performance.

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ABSTRACT: A numerical study is executed to analyze the steady-state heatlines visualization, fluid flow, and heat transfer inside a square enclosure with the presence of the magnetic field. The enclosure is divided into three layers, the right and left layers are filled with (Cu-Water) nanofluid while the center layer is sinusoidal porous and filled with the same nanofluid. Constant hot and cold temperature is applied to the right and left walls, respectively, the top and bottom walls are adiabatic. Galerkin finite element approach based on weak formulation is applied to solve the governing equations. The parameters studied are the number of undulation (N=1, 2 and 3), Rayleigh number (103≤Ra≤106), Darcy number (10-5≤Da≤10-1), Hartmann number (0≤Ha≤100) and volume fraction (0≤φ≤0.06). Three cases were provided depending on the number of undulations of the porous medium layer. The results obtained that the absolute value of the maximum stream function decreases with the increase of the Hartmann number and the decrease of the Darcy number for all three cases of the wavy porous layer. Heatlines and isothermal lines increase as the Darcy number is increased. The average Nusselt number grows by increasing the Rayleigh number and decreasing the Hartmann number. The enhancement of heat transfer occurred for case (2) as the Darcy number increased at a constant Ra=105, Ha=40. Also, It can be concluded that there was an excellent agreement between this study and those of Hamida and Charrada, by an approximately maximum absolute error of 2.062%

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In this article, an investigational analysis has been conducted to explore the effect of biodiesel fuel blends on characteristics of engine and releases (CO2, CO, HCl, and NOx) of single-cylinder, four strokes at the variable biodiesel concentration. The releases of gases and the engine's characteristics were measured at six blending biofuels and six-speed conditions and constant load. The blending proportions of biodiesel with diesel fuel-based by volume were at 0% pure diesel, 5%, 10%, 15%, 20%, and 25%. This investigation aims to assess the biodiesel fuel mixture's impact on the CI engine performance in terms of its Bsfc, Ƞbth, and engine release of CO2, CO, HCl, and NOx. The investigation revealed that biodiesel remarkably minimized the release of CO2, CO, HCl, and NOx. The influence of this fuel mixture was studied between 5% to25% biodiesel concentration, and the results of this investigation could aid in understanding the Impact of utilizing biodiesel as an energy source on engine releases and performances.