| 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. |
- Al-Obaidi, Mohammed, et al.
(författare)
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Hardware Acceleration of the Robust Header Compression (RoHC) Algorithm
- 2013
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Ingår i: 2013 IEEE International Symposium on Circuits and Systems (ISCAS). - 2158-1525 .- 0271-4310. - 9781467357623 - 9781467357609 ; , s. 293-296
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Konferensbidrag (refereegranskat)abstract
- In LTE base-stations, RoHC is a processingintensive algorithm that may limit the system from serving a large number of users when it is used to compress the VoIP packets of mobile traffic. In this paper, a hardware-software and a full-hardware solution are proposed to accelerate the RoHC compression algorithm in LTE base-stations and enhance the system throughput and capacity. Results for both solutions are discussed and compared with respect to design metrics like throughput, capacity, power consumption, and hardware resources. This comparison is instrumental in taking architectural level trade-off decisions in-order to meet the present day requirements and also be ready to support a future evolution. In terms of throughput, a gain of 20% (6250 packets/sec) is achieved in the HW-SW implementation by accelerating the Cyclic Redundancy Check (CRC) and the Least Significant Bit (LSB) encoding in hardware. The full-HW implementation leads to a throughput of 45 times (244000 packets/sec) compared to the SW-Only implementation. The full-HW solution consumes more Adaptive Look-Up Tables (7477 ALUTs) compared to the HW-SW solution (2614 ALUTs) when synthesized on Altera’s Arria II GX FPGA.
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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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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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