| 1. |
- Al-Obaidi, Mudhar A., et al.
(författare)
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Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators
- 2024
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Ingår i: Water. - : MDPI. - 2073-4441. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.
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| 2. |
- Khalaf, Abbas Fadhil, et al.
(författare)
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A Numerical Study of the Effect of Water Speed on the Melting Process of Phase Change Materials Inside a Vertical Cylindrical Container
- 2024
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 14:8
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Tidskriftsartikel (refereegranskat)abstract
- The present work offers a thorough analysis of the impact of water velocity on phase change material (PCM) melting in a vertical cylindrical container. A detailed quantitative analysis uses sophisticated numerical techniques, namely the ANSYS/FLUENT 16 program, to clarify the complex relationship between enthalpy and porosity during the melting process. The experimental focus is on phase transition materials based on paraffin wax, particularly Rubitherm RT42. This study’s primary goal is to evaluate the effects of different water velocities (that is, at velocities of 0.01 m/s, 0.1 m/s, and 1 m/s) on the PCM’s melting behavior at a constant temperature of 333 K. This work intends to make a substantial contribution to the development of thermal energy storage systems by investigating new perspectives on PCM behavior under various flow circumstances. The study’s key findings highlight the possible ramifications for improving PCM-based thermal energy storage devices by revealing significant differences in melting rates and behavior that correlate to changes in water velocities. Future research is recommended to explore the impact of temperature variations, container geometries, and experimental validation to improve the accuracy and practicality of the results and to advance the creation of sustainable and effective energy storage solutions.
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| 3. |
- Khalaf, Abbas Fadhil, et al.
(författare)
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Numerical investigation of the effect of an air layer on the melting process of phase change materials
- 2024
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Ingår i: Materials for Renewable and Sustainable Energy. - : Springer. - 2194-1459 .- 2194-1467.
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Tidskriftsartikel (refereegranskat)abstract
- Designing more effective thermal energy storage devices can result from understanding how air layers impact the melting process. The total efficiency of these systems can be improved by optimizing the melting process of the phase change materials (PCMs), which are utilised to store and release thermal energy. The current study utilises an analysis to evaluate how an air layer would affect melting of the PCM. The enthalpy-porosity combination based ANSYS/FLUENT 16 software is specifically used to accomplish this study, considering the paraffin wax (RT42) as the PCM. The study reveal that the presence of an air layer would impact the dissolution process. This result is assured an increase of melting time of PCM by 125% as a result to having an air layer of 5 cm thickness compared to a cell without an air layer. Furthermore, an increase of the layer thickness beyond 5 cm has a progressive effect on the melting time of PCM. One important component that affects the melting process is the existence of an air layer above the cell. Greater heat transfer resistance from thicker air layers prolongs the time needed to finish melting. The efficient heat transmission of PCM is shown to be reduced when there is an air layer above the cell. The melting process gradually slows down as the air layer thickness rises, which reflects the decreased heat transmission. These results highlight how crucial it is to take the environment into account while creating PCM-filled energy storage cells.
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| 4. |
- Rashid, Farhan Lafta, et al.
(författare)
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A Review of Using Solar Energy for Cooling Systems: Applications, Challenges, and Effects
- 2023
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:24
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Forskningsöversikt (refereegranskat)abstract
- Energy security refers to a country’s capacity to provide the energy resources essential to its wellbeing, including a reliable supply at an affordable costs. Economic growth and development cannot occur without access to reliable energy sources. Energy availability is a proxy for a country’s standard of living and a key factor in its economic development and technical progress. Solar power is the most reliable and cost-effective option when it comes to meeting the world’s energy needs. Solar-powered cooling systems are one example of how solar energy may be used in the real world. Solar-powered air conditioners have become more popular in recent years. The problems caused by our reliance on fossil fuels may be surmounted with the help of solar cooling systems that use solar collectors. Solar cooling systems may utilize low-grade solar energy, making them popular in the construction industry. Solar cooling systems powered by photovoltaic–thermal (PVT) collectors have been the subject of much research to improve the thermodynamic and economic performance of solar cooling systems. This research focuses on exploring the potential of solar-generated heat for use in cooling systems. This study will also examine the current challenges involved with using solar energy in cooling applications, as well as the possible benefits that may help pave the way for more research and greater employment of heat gain from the solar system in various cooling applications.
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| 5. |
- Rashid, Farhan Lafta, et al.
(författare)
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Advancements in Fresnel Lens Technology across Diverse Solar Energy Applications: A Comprehensive Review
- 2024
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Concentration of solar energy may be obtained by reflection, refraction, or a combination of the two. The collectors of a reflection system are designed to concentrate the sun’s rays onto a photovoltaic cell or steam tube. Refractive lenses concentrate light by having it travel through the lens. The sun’s rays are partially reflected and then refracted via a hybrid technique. Hybrid focus techniques have the potential to maximize power output. Fresnel lenses are an efficient tool for concentrating solar energy, which may then be used in a variety of applications. Development of both imaging and non-imaging devices is occurring at this time. Larger acceptance angles, better concentration ratios with less volume and shorter focal length, greater optical efficiency, etc., are only some of the advantages of non-imaging systems over imaging ones. This study encompasses numerical, experimental, and numerical and experimental studies on the use of Fresnel lenses in various solar energy systems to present a comprehensive picture of current scientific achievements in this field. The framework, design criteria, progress, and difficulties are all dissected in detail. Accordingly, some recommendations for further studies are suggested.
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| 6. |
- Rashid, Farhan Lafta, et al.
(författare)
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Analysis of heat transfer in various cavity geometries with and without nano-enhanced phase change material: A review
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 3757-3779
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Forskningsöversikt (refereegranskat)abstract
- Numerous heating and cooling design methods, including energy storage, geothermal resources, heaters, solar collectors, underground water movement, lakes, and nuclear reactors, require the study of flow regimes in a cavity and their impact on thermal efficiency in heat transportation. Despite the existence of several review studies in the open literature, there is no specific review of heat transfer investigations that consider different cavity designs, such as spheres, squares, trapezoids, and triangles. Therefore, this work aims to conduct a comprehensive review of previous research published between 2016 and 2023 on heat transfer analysis in these cavity designs. The intention is to clarify how various cavity shapes perform in terms of flow and heat transfer, both with and without the addition of nano-enhanced phase change materials (NePCMs), which may include fins, obstacles, cylinders, and baffles. The study also explores the influence of factors like thermophoresis, buoyancy, magnetic forces, and others on heat transport in cavities. Additionally, it investigates the role of air, water, nanofluids, and hybrid nanofluids within cavities. According to the reviewed research, nanoparticles in the base fluid speed up the cooling process and reduce the required discharging time. Thermophoresis, where nanoparticles move from the heated wall to the cold nanofluid flow, becomes more pronounced with increasing Reynolds numbers. Increasing the heated area of the lower flat fin enhances the heat transfer rate, while increasing both the Rayleigh number and the solid volume percentage of nanoparticles reduces it. Radiation blockage alters the path of hot particles and affects the anticipated radiative amount. Optical thickness plays a role in rapidly cooling a medium, and partition thickness has the most significant effect on heat transport when the thermal conductivity ratio is low. Heat transmission is most improved when the Rayleigh number is high and the Richardson number is low.
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| 7. |
- Rashid, Farhan Lafta, et al.
(författare)
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Enhancement of Polyacrylic Acid/Silicon Carbide Nanocomposites’ Optical Properties for Potential Application in Renewable Energy
- 2024
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Ingår i: Journal of Composites Science. - : MDPI. - 2504-477X. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical properties for use in solar collectors and thermal energy storage (TES) fields. The optical properties of PAA−SiC nanocomposites are investigated within the wavelength between 340 and 840 nm. The findings indicate that an increase in SiC concentration in the PAA aqueous solution to 50 g/L at a wavelength of λ = 400 nm causes an increase in the absorption by 50.2% besides a reduction in transmission by 6%. Furthermore, the energy band gaps were reduced from 3.25 eV to 2.95 eV to allow for the transition, and subsequently reduced from 3.15 eV to 2.9 eV to allow for forbidden transition as a result of the increasing SiC concentration from 12.5 g/L to 50 g/L. The optical factors of energy absorption and optical conductivity were also enhanced with a rising SiC concentration from 12.5 to 50 g/L. Specifically, an improvement of 61% in the melting time of PAA−SiC−H2O nanofluids is concluded. Accordingly, it can be said that the PAA−SiC−H2O nanofluids are suitable for renewable energy and TES systems.
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| 8. |
- Rashid, Farhan Lafta, et al.
(författare)
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Heat Convection in a Channel-Opened Cavity with Two Heated Sources and Baffle
- 2024
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- This study employs COMSOL software v 5.6 to investigate a novel approach to heat transfer via mixed convection in an open hollow structure with an unheated 90° baffle elbow. Two 20 W heat sources are strategically positioned on the cavity’s bottom and right-angled wall for this research. Notably, the orientation of the baffle perpendicular to the airflow is used to direct external, unrestricted flow into the square cavity. The research investigates a range of air velocities (0.1, 0.5, 1.0, and 1.5 m/s) and the intricate interaction between input air velocity, dual heated sources, and the presence of a right-angle baffle on critical thermodynamic variables, such as temperature distribution, isotherms, pressure variation, velocity profile, air density, and both local and mean Nusselt numbers. Validation of the applicable computational method is achieved by comparing it to two previous studies. Significant findings from numerical simulations indicate that the highest velocity profile is in the centre of the channel (2.3–2.68 m/s at an inflow velocity of 1.5 m/s), while the lowest profile is observed along the channel wall, with a notable disruption near the inlet caused by increased shear forces. The cavity neck temperature ranges from 380 to 640 K, with inflow air velocities varying from 0.1 to 1.5 m/s (Re is 812 to 12,182), respectively. In addition, the pressure fluctuates at the channel-cavity junction, decreasing steadily along the channel length and reaching a maximum at the intake, where the cavity neck pressure varies from 0.01 to 2.5 Pa with inflow air velocities changing from 0.1 to 1.5 m/s, respectively. The mean Nusselt number exhibits an upward trend as air velocity upon entry increases. The mean Nusselt number reaches up to 1500 when the entry air velocity reaches 1.5 m/s. Due to recirculation patterns, the presence of the 90° unheated baffle produces a remarkable cooling effect. The study establishes a direct correlation between input air velocity and internal temperature distribution, indicating that as air velocity increases, heat dissipation improves. This research advances our understanding of convective heat transfer phenomena in complex geometries and provides insights for optimising thermal management strategies for a variety of engineering applications.
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| 9. |
- Rashid, Farhan Lafta, et al.
(författare)
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Investigating the Impact of Cell Inclination on Phase Change Material Melting in Square Cells: A Numerical Study
- 2024
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- In order to determine the ideal degree of inclination that should be employed for constructing effective thermal energy storage systems, it is important to examine the impact of inclination angle on the melting behavior of phase change materials (PCMs) such as paraffin wax within a square cell. In consequence, this would guarantee the greatest capacity for energy release and storage. Additionally, analyzing this influence aids engineers in creating systems that enhance heat flow from external sources to the PCM and vice versa. To find out how the cell’s inclination angle affects the melting of PCM of paraffin wax (RT42) inside a square cell, a numerical analysis is carried out using the ANSYS/FLUENT 16 software. Specifically, the temperature and velocity distributions, together with the evolution of the melting process, will be shown for various inclination angles, and a thorough comparison will be made to assess the influence of inclination angle on the PCM melting process and its completion. The findings demonstrated that when the cell’s inclination angle increased from 0° to 15° and from 0° to 30° and 45°, respectively, the amount of time required to finish the melting process increased by 15%, 42%, and 71%, respectively. Additionally, after 210 min of operation, the PCM’s maximum temperature is 351.5 K with a 0° angle of inclination (horizontal) against 332.5 K with an angle of inclination of 45°.
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| 10. |
- Rashid, Farhan Lafta, et al.
(författare)
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Investigation of Thermo-Hydraulics in a Lid-Driven Square Cavity with a Heated Hemispherical Obstacle at the Bottom
- 2024
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Ingår i: Entropy. - : MDPI. - 1099-4300. ; 26:5
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Tidskriftsartikel (refereegranskat)abstract
- Lid-driven cavity (LDC) flow is a significant area of study in fluid mechanics due to its common occurrence in engineering challenges. However, using numerical simulations (ANSYS Fluent) to accurately predict fluid flow and mixed convective heat transfer features, incorporating both a moving top wall and a heated hemispherical obstruction at the bottom, has not yet been attempted. This study aims to numerically demonstrate forced convection in a lid-driven square cavity (LDSC) with a moving top wall and a heated hemispherical obstacle at the bottom. The cavity is filled with a Newtonian fluid and subjected to a specific set of velocities (5, 10, 15, and 20 m/s) at the moving wall. The finite volume method is used to solve the governing equations using the Boussinesq approximation and the parallel flow assumption. The impact of various cavity geometries, as well as the influence of the moving top wall on fluid flow and heat transfer within the cavity, are evaluated. The results of this study indicate that the movement of the wall significantly disrupts the flow field inside the cavity, promoting excellent mixing between the flow field below the moving wall and within the cavity. The static pressure exhibits fluctuations, with the highest value observed at the top of the cavity of 1 m width (adjacent to the moving wall) and the lowest at 0.6 m. Furthermore, dynamic pressure experiences a linear increase until reaching its peak at 0.7 m, followed by a steady decrease toward the moving wall. The velocity of the internal surface fluctuates unpredictably along its length while other parameters remain relatively stable.
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