Application of the ANOVA method in the optimization of a thermoelectric cooler-based dehumidification system

© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).In recent studies, Thermo-Electric Coolers (TEC) have been utilized for dehumidification purposes, which is mainly based on the extraction of moisture from humid atmospheric air. The reviewed literature showed that the rate of water collection from the TEC-based system can be affected by various parameters such as the module’s input voltage, the heat sink orientation, and tilt angles. In this research, the analysis of variance (ANOVA) was used to examine the significance of these factors and their interaction within the system on the TEC-based dehumidification system. Four levels were investigated for both, the Peltier’s input voltage and the rotation angle, and three levels for the tilt angle. This study indicated the significance of the studied factors and their interactions within the dehumidification system along with performing an overall numerical optimization. The experiments were conducted under the same working conditions in an enclosed environment to minimize errors. According to the overall numerical optimization, which was validated experimentally, the optimum system performance was predicted to be obtained at approximately 6.8V Peltier input volt, 65° rotation angle, and 90° tilt angles, with predicted optimum productivities of 0.32278 L/kWh and 13.03 mL/hr. For the same set of parameters, the variation between the experiment and the numerical optimization was less than 4%. The experiments show that when optimizing water collection rates for thermoelectric cooling heat sinks​ under high humidity conditions, the orientation of the heat sink should be considered.Peer reviewe

Thermohydraulic analysis of covalent and noncovalent functionalized graphene nanoplatelets in circular tube fitted with turbulators

© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Covalent and non-covalent nanofluids were tested inside a circular tube fitted with twisted tape inserts with 45° and 90° helix angles. Reynolds number was 7000 ≤ Re ≤ 17,000, and thermophysical properties were assessed at 308 K. The physical model was solved numerically via a two-equation eddy-viscosity model (SST k-omega turbulence). GNPs-SDBS@DW and GNPs-COOH@DW nanofluids with concentrations (0.025 wt.%, 0.05 wt.% and 0.1 wt.%) were considered in this study. The twisted pipes' walls were heated under a constant temperature of 330 K. The current study considered six parameters: outlet temperature, heat transfer coefficient, average Nusselt number, friction factor, pressure loss, and performance evaluation criterion. In both cases (45° and 90° helix angles), GNPs-SDBS@DW nanofluids presented higher thermohydraulic performance than GNPs-COOH@DW and increased by increasing the mass fractions such as 1.17 for 0.025 wt.%, 1.19 for 0.05 wt.% and 1.26 for 0.1 wt.%. Meanwhile, in both cases (45° and 90° helix angles), the value of thermohydraulic performance using GNPs-COOH@DW was 1.02 for 0.025 wt.%, 1.05 for 0.05 wt.% and 1.02 for 0.1 wt.%.Peer reviewe

Proceedings of Abstracts, School of Physics, Engineering and Computer Science Research Conference 2022

© 2022 The Author(s). This is an open-access work distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For further details please see https://creativecommons.org/licenses/by/4.0/. Plenary by Prof. Timothy Foat, ‘Indoor dispersion at Dstl and its recent application to COVID-19 transmission’ is © Crown copyright (2022), Dstl. This material is licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: [email protected] present proceedings record the abstracts submitted and accepted for presentation at SPECS 2022, the second edition of the School of Physics, Engineering and Computer Science Research Conference that took place online, the 12th April 2022

Analysis of Standby Power in an Enclosed High-Speed Flywheel Energy Storage System Using the CFD-ANOVA Approach

© 2023 SAE International. This is the accepted manuscript version of an article which has been published in final form at https://saemobilus-sae-org.ezproxy.herts.ac.uk/content/2023-32-0069/During urban driving, a significant amount of energy is lost due to continuous braking, which can be recovered and stored. The flywheel energy storage system (FESS) can efficiently recover and store the vehicle's kinetic energy during deceleration. However, standby losses in FESS, primarily due to aerodynamic drag, can affect its overall efficiency. To address this issue, the flywheel rotor is typically housed in a dedicated housing maintained at a low pressure using a vacuum pump. Standby power is known as the total power used by the auxiliary systems and the power needed to overcome drag and keep the flywheel rotor at a specific state of charge. The Analysis of Variance (ANOVA) technique was combined with the computational fluid dynamics (CFD) technique in this study to determine the optimal flywheel design parameters and investigate their impact on standby power. The study's results demonstrated the optimal combination of the airgap size and the rotor's pressure cavity to achieve the lowest standby power.Peer reviewe

Towards a sustainable energy future for Egypt: A systematic review of renewable energy sources, technologies, challenges, and recommendations

© 2022 Published by Elsevier Ltd. This is an open access article under the CC BY license, https://creativecommons.org/licenses/by/4.0/Egypt has a significant role in international energy transit, being one of the major economies in the African continent. However, its energy sector is still overwhelmed with the local energy demands. It has been predicted that Egypt's CO 2 emissions could increase by around 125% from 2012 to 2035 if the nation's energy demand is met using conventional power generation technologies. Given that Egypt has signed the Kyoto protocol and recognised the role of international cooperation in facing climate change, the country should focus on meeting the growing energy demand using clean energy technologies. In the meantime, Egypt has been facing many challenges due to the water scarcity issues and environmental risks arising from the lack of efficient solid waste management strategies over the last few decades. It has been predicted that the country's crude oil reserves might be depleted within the next 15 years or so. To face these challenges effectively and enforce the Egyptian role in international energy transit, renewable energy (RE) technologies and their applications should be the main focus of the current/future Egyptian energy frameworks. This review summarises the current energy outlook of Egypt while analysing the country's potential to harness energy from sustainable sources. In general, it has been found that Egypt's renewable energy sector is yet to be exploited for sustainable energy production through its diverse and plentiful resources. Eventually, two scenarios have been proposed to consider in achieving the nation's 2035 energy target, which is to generate 42% of the country's energy need through renewable sources. This study should help Egypt and other countries to set the way forward in achieving the NET ZERO target that the whole world aims to fulfil over the next few decades.Peer reviewe

Development of a CFD Model for the Estimation of Windage Losses Inside the Narrow Air Gap of an Enclosed High-Speed Flywheel

Concerns over global warming and the need to reduce carbon emissions have prompted the development of novel energy recovery systems. During urban driving, a significant amount of energy is lost due to continuous braking, which can be recovered and stored. The flywheel energy storage system can efficiently recover and store the vehicle's kinetic energy during deceleration. In this study, a Computational Fluid Dynamics (CFD) model was developed to assess the impact of air gap size, and rotor cavity pressure environment on the aerodynamic performance of an enclosed non-ventilated flywheel energy recovery system. Consequently, the flywheel rotor skin friction coefficients for various air gap sizes have been numerically determined to predict the windage losses over a wide operating range. The presented study aims to identify a correlation that accurately fits the rotor skin friction coefficients for a range of air gap sizes and operating conditions. Model validation was carried out to assess the validity of the CFD results, which showed good agreement between numerical and experimental data. The results demonstrated that the increase in the air gap size can lead to up to a 19% reduction in the windage loss depending on the operating speed of the flywheel, while the windage loss can be reduced by 33% when the operating pressure is reduced to 500 mbar. Windage losses can be reduced by 45% when the airgap size is greatest, and the operating pressure is lowest.Peer reviewe

Numerical analysis of a flywheel energy storage system for low carbon powertrain applications

© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Flywheel energy storage has emerged as a viable energy storage technology in recent years due to its large instantaneous power and high energy density. Flywheel offers an onboard energy recovery and storage system which is durable, efficient, and environmentally friendly. The flywheel and the housing surface temperatures can be considerably influenced by the friction induced windage losses associated with non-vented airflows in the air-gap of a high-speed rotating flywheel. Many engineering applications have been interested in the features of radial and axial air-gap flows. The flow within the annulus of a flywheel is extremely complicated. This study has developed a numerical technique using ANSYS Fluent solver to model turbulent Taylor vortices formation and oscillation for thermal performance evaluation, and windage loss prediction of high-speed flywheel storage systems, operating under atmospheric and partial vacuum conditions. The numerical model has been experimentally validated with good accuracy. Several rotational speeds and pressures were investigated experimentally and numerically. The results demonstrated that a 40% reduction in the operating pressure can reduce the flywheel surface temperature and windage loss by 20% and 30%, respectively. Consequently, a partial vacuum environment can achieve better energy conversion efficiencies provided an appropriate bearing seal is achieved to maintain the pressure inside the housing. The investigated flywheel energy storage system can reduce the fuel consumption of an average light-duty vehicle in the UK by 22% and decrease CO2 emission by 390 kg annually.Peer reviewe

Deep clustering of cooperative multi-agent reinforcement learning to optimize multi chiller HVAC systems for smart buildings energy management

© 2022 Elsevier Ltd. All rights reserved. All rights reserved. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1016/j.jobe.2022.105689Chillers are responsible for almost half of the total energy demand in buildings. Hence, the obligation of control systems of multi-chiller due to changes indoor environments is one of the most significant parts of a smart building. Such a controller is described as a nonlinear and multi-objective algorithm, and its fabrication is crucial to achieving the optimal balance between indoor thermal comfort and running a minimum number of chillers. This work proposes deep clustering of cooperative multi-agent reinforcement learning (DCCMARL) as well-suited to such system control, which supports centralized control by learning of agents. In MARL, since the learning of agents is based on discrete sets of actions and stats, this drawback significantly affects the model of agents for representing their actions with efficient performance. This drawback becomes considerably worse when increasing the number of agents, due to the increased complexity of solving MARL, which makes modeling policy very challenging. Therefore, the DCCMARL of multi-objective reinforcement learning is leveraging powerful frameworks of a hybrid clustering algorithm to deal with complexity and uncertainty, which is a critical factor that influences to the achievement of high levels of a performance action. The results showed that the ability of agents to manipulate the behavior of the smart building could improve indoor thermal conditions, as well as save energy up to 44.5% compared to conventional methods. It seems reasonable to conclude that agents' performance is influenced by what type of model structure.Peer reviewe

Influence of water based binary composite nanofluids on thermal performance of solar thermal technologies: sustainability assessments

Recent technological advances have made it possible to produce particles with nanometer dimensions that are uniformly and steadily suspended in traditional solar liquids and have enhanced the impact of thermo-physical parameters. In this research, a three-dimensional flat plate solar collector was built using a thin flat plate and a single working fluid pipe. The physical model was solved computationally under conditions of conjugated laminar forced convection in the range 500 ≤ Re ≤ 1900 and a heat flux of 1000 W/m2. Distilled water (DW) and different types of hybrid nanofluids (namely, 0.1%-Al2O3@Cu/DW, 0.1%-MWCNTs@Fe3O4/DW, 0.3%-MWCNTs@Fe3O4/DW, 0.5%-Ag@MgO/DW, 1%-Ag@MgO/DW, 1%-S1 and 1%-S2, where MWCNTs are multi-wall carbon nanotubes, S1 means 2CuO–1Cu and S2 means 1CuO–2Cu nanocomposites) were evaluated via a set of parameters. The numerical results revealed that, by increasing the working fluid velocity (the Reynolds number), the average heat transfer coefficient, pressure loss, heat gain and solar collector efficiency were increased. Meanwhile, outlet fluid temperature and flat plate surface temperature were decreased. At Re = 1900, 1%-S2 and 1%-S1 presented higher thermal performance enhancement by 44.28% and 36.72% relative to DW. Moreover, low thermal performance enhancement of 7.59% and 7.44% were reported by 0.1%-Al2O3@Cu/DW and 0.3%-MWCNTs@Fe3O4/DW, respectively.Validerad;2023;Nivå 2;2023-01-25 (joosat);Licens fulltext: CC BY License</p