Search results for: overall thermal efficiency

Authors: Amir Sattari, Mac Panah, Naeim Rashidfarokhi

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To enhance the mixing of fluid in a rectangular enclosure with a circular inlet and outlet, an energy-efficient approach is further investigated through computational fluid dynamics (CFD). Particle image velocimetry (PIV) measurements help confirm that the pulsation of the inflow velocity improves the mixing performance inside the enclosure considerably without increasing energy consumption. In this study, multiple CFD simulations with different turbulent models were performed. The results obtained were compared with experimental PIV results. This study investigates small-scale representations of flow patterns in a ventilated rectangular room. The objective is to validate the concept of an energy-efficient ventilation strategy with improved thermal comfort and reduction of stagnant air inside the room. Experimental and simulated results confirm that through pulsation of the inflow velocity, strong secondary vortices are generated downstream of the entrance wall-jet. The pulsatile inflow profile promotes a periodic generation of vortices with stronger eddies despite a relatively low inlet velocity, which leads to a larger boundary layer with increased kinetic energy in the occupied zone. A real-scale study was not conducted; however, it can be concluded that a constant velocity inflow profile can be replaced with a lower pulsated flow rate profile while preserving the mixing efficiency. Among the turbulent CFD models demonstrated in this study, SST-kω is most advantageous, exhibiting a similar global airflow pattern as in the experiments. The detailed near-wall velocity profile is utilized to identify the wall-jet instabilities that consist of mixing and boundary layers. The SAS method was later applied to predict the turbulent parameters in the center of the domain. In both cases, the predictions are in good agreement with the measured results.

Keywords: CFD, PIV, pulsatile inflow, ventilation, wall-jet

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Authors: Yoshifumi Hino

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An infinitely repeated prisoner’s dilemma is a typical model that represents teamwork situation. If both players choose costly actions and contribute to the team, then both players are better off. However, each player has an incentive to choose a selfish action. We analyze the game under costly observation. Each player can observe the action of the opponent only when he pays an observation cost in that period. In reality, teamwork situations are often costly observation. Members of some teams sometimes work in distinct rooms, areas, or countries. In those cases, they have to spend their time and money to see other team members if they want to observe it. The costly observation assumption makes the cooperation difficult substantially because the equilibrium must satisfy the incentives not only on the action but also on the observational decision. Especially, it is the most difficult to cooperate each other when the stage-game is prisoner's dilemma because players have to communicate through only two actions. We examine whether or not players can cooperate each other in prisoner’s dilemma under costly observation. Specifically, we check whether symmetric Pareto efficient payoff vectors in repeated prisoner’s dilemma can be approximated by sequential equilibria or not (efficiency result). We show the efficiency result without any randomization device under certain circumstances. It means that players can cooperate with each other without any randomization device even if the observation is costly. Next, we assume that public randomization device is available, and then we show that any feasible and individual rational payoffs in prisoner’s dilemma can be approximated by sequential equilibria under a specific situation (folk theorem). It implies that players can achieve asymmetric teamwork like leadership situation when public randomization device is available.

Keywords: cost observation, efficiency, folk theorem, prisoner's dilemma, private monitoring, repeated games.

Procedia PDF Downloads 235

Authors: Sandesh Achar

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The cloud computing industry has set new goals for better service delivery and deployment, so anyone can access services such as computation, application, and storage anytime. Cloud computing promises new possibilities for approaching sustainable solutions to deploy and advance their services in this distributed environment. This work explores energy-efficient approaches and how cloud-based architecture can reduce energy consumption levels amongst enterprises leveraging cloud computing services. Adopting cloud-based networking, database, and server machines provide a comprehensive means of achieving the potential gains in energy efficiency that cloud computing offers. In energy-efficient cloud computing, virtualization is one aspect that can integrate several technologies to achieve consolidation and better resource utilization. Moreover, the Green Cloud Architecture for cloud data centers is discussed in terms of cost, performance, and energy consumption, and appropriate solutions for various application areas are provided.

Keywords: greener cloud, cloud computing, energy efficiency, energy consumption, metadata tags, green cloud advisor

Procedia PDF Downloads 79

Authors: Ana Carolina Kogawa, Selma Gutierrez Antonio, Hérida Regina Nunes Salgado

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Rifaximin is an oral antimicrobial, gut - selective and not systemic with adverse effects compared to placebo. It is used for the treatment of hepatic encephalopathy, travelers diarrhea, irritable bowel syndrome, Clostridium difficile, ulcerative colitis and acute diarrhea. The crystalline form present in the rifaximin with minimal systemic absorption is α, being the amorphous form significantly different. Regulators are increasingly attention to polymorphisms. Polymorphs can change the form by altering the drug characteristics compromising the effectiveness and safety of the finished product. International Conference on Harmonization issued the ICH Guidance Q6A, which aim to improve the control of polymorphism in new and existing pharmaceuticals. The objective of this study was to obtain polymorphic forms of rifaximin employing recrystallization processes and characterize them by thermal analysis (thermogravimetry - TG and differential scanning calorimetry - DSC), X-ray diffraction, scanning electron microscopy and solubility test. Six polymorphic forms of rifaximin, designated I to VI were obtained by the crystallization process by evaporation of the solvent. The profiles of the TG curves obtained from polymorphic forms of rifaximin are similar to rifaximin and each other, however, the DTG are different, indicating different thermal behaviors. Melting temperature values of all the polymorphic forms were greater to that shown by the rifaximin, indicating the higher thermal stability of the obtained forms. The comparison of the diffractograms of the polymorphic forms of rifaximin with rifaximin α, β and γ constant in patent indicate that forms III, V and VI are formed by mixing polymorph β and α and form III is formed by polymorph β. The polymorphic form I is formed by polymorph β, but with a significant amount of amorphous material. Already, the polymorphic form II consists of polymorph γ, amorphous. In scanning electron microscope is possible to observe the heterogeneity of morphological characteristics of crystals of polymorphic forms among themselves and with rifaximin. The solubility of forms I and II was greater than the solubility of rifaximin, already, forms III, IV and V presented lower solubility than of rifaximin. Similarly, the bioavailability of the amorphous form of rifaximin is considered significantly higher than the form α, the polymorphic forms obtained in this work can not guarantee the excellent tolerability of the reference medicine. Therefore, studies like these are extremely important and they point to the need for greater requirements by the regulatory agencies competent about polymorphs analysis of the raw materials used in the manufacture of medicines marketed globally. These analyzes are not required in the majority of official compendia. Partnerships between industries, research centers and universities would be a viable way to consolidate researches in this area and contribute to improving the quality of solid drugs.

Keywords: electronic microscopy, polymorphism, rifaximin, solubility, X-ray diffraction

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Authors: C. Trapp, A. Vijay, M. Khorasani

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Decentralised micro-grids with sector coupling can combat the spatial and temporal intermittence of renewable energy by combining power, transportation and infrastructure sectors. Intelligent energy conversion concepts such as electrolysers, hydrogen engines and fuel cells combined with energy storage using intelligent batteries and hydrogen storage form the back-bone of such a system. This paper describes a micro-grid based on Photo-Voltaic cells, battery storage, innovative modular and scalable Anion Exchange Membrane (AEM) electrolyzer with an efficiency of up to 73%, high-pressure hydrogen storage as well as cutting-edge combustion-engine based Combined Heat and Power (CHP) plant with more than 85% efficiency at the university campus to address the challenges of decarbonization whilst eliminating the necessity for expensive high-voltage infrastructure.

Keywords: sector coupling, micro-grids, energy self-sufficiency, decarbonization, AEM electrolysis, hydrogen CHP

Procedia PDF Downloads 174

Authors: Can Hu, Huixia Shi, Hongcheng Mei, Jun Zhu, Hongling Guo

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Textile fibers are important trace evidence and frequently encountered in criminal investigations. A significant aspect of fiber evidence examination is the determination of fiber dyes. Although several instrumental methods have been developed for dyes detection, the analysis speed is not fast enough yet. A rapid dye analysis method is still needed to further improve the efficiency of case handling. Capillary electrophoresis has the advantages of high separation speed and high separation efficiency and is an ideal method for the rapid analysis of fiber dyes. In this paper, acid dyes used for protein fiber dyeing were determined by a developed short-end injection capillary electrophoresis technique. Five acid red dyes with similar structures were successfully baseline separated within 5 min. The separation reproducibility is fairly good for the relative standard deviation of retention time is 0.51%. The established method is rapid and accurate which has great potential to be applied in forensic setting.

Keywords: acid dyes, capillary electrophoresis, fiber evidence, rapid determination

Procedia PDF Downloads 143

Authors: Mohamed T. Faheem Saidahmed, Ahmed M. Attiya Ibrahim, Basma GH. Elkilany

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This paper discusses the application of Time Delay Control (TDC) compensation technique in the juice extraction process in a sugar mill. The objective is to improve the control performance of the process and increase extraction efficiency. The paper presents the mathematical model of the juice extraction process and the design of the TDC compensation controller. Simulation results show that the TDC compensation technique can effectively suppress the time delay effect in the process and improve control performance. The extraction efficiency is also significantly increased with the application of the TDC compensation technique. The proposed approach provides a practical solution for improving the juice extraction process in sugar mills using MATLAB Processes.

Keywords: time delay control (TDC), exact and unique state space model, delay compensation, Smith predictor.

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Authors: Ganesh R. Bhand, N. B. Chaure

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Cadmium selenide (CdSe) quantum dots (QDs) were prepared by solvothermal route. Subsequently a inorganic QDs-organic semiconductor (copper phthalocyanine) nanocomposite (i.e CuPc:CdSe nanocomposites) were produced by different concentration of QDs varied in CuPc. The nanocomposite thin films have been prepared by means of spin coating technique. The optical, structural and morphological properties of nanocomposite films have been investigated. The transmission electron microscopy (TEM) confirmed the formation of QDs having average size of  4 nm. The X-ray diffraction pattern exhibits cubic crystal structure of CdSe with reflection to (111), (220) and (311) at 25.4ᵒ, 42.2ᵒ and 49.6ᵒ respectively. The additional peak observed at lower angle at 6.9ᵒ in nanocomposite thin films are associated to CuPc. The field emission scanning electron microscopy (FESEM) observed that surface morphology varied in increasing concentration of CdSe QDs. The obtained nanocomposite show significant improvement in the thermal stability as compared to the pure CuPc indicated by thermo-gravimetric analysis (TGA) in thermograph. The effect in the Raman spectra of composites samples gives a confirm evidence of homogenous dispersion of CdSe in the CuPc matrix and their strong interaction between them to promotes charge transfer property. The success of reaction between composite was confirmed by Fourier transform infrared spectroscopy (FTIR). The photo physical properties were studied using UV - visible spectroscopy. The enhancement of the optical absorption in visible region for nanocomposite layer was observed with increasing the concentration of CdSe in CuPc. This composite may obtain the maximized interface between QDs and polymer for efficient charge separation and enhance the charge transport. Such nanocomposite films for potential application in fabrication of hybrid solar cell with improved power conversion efficiency.

Keywords: CdSe QDs, cupper phthalocyanine, FTIR, optical absorption

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Authors: R. Blythman, N. Jeffers, T. Persoons, D. B. Murray

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The exploitation of flow pulsation in micro- and mini-channels is a potentially useful technique for enhancing cooling of high-end photonics and electronics systems. It is thought that pulsation alters the thickness of the hydrodynamic and thermal boundary layers, and hence affects the overall thermal resistance of the heat sink. Although the fluid mechanics and heat transfer are inextricably linked, it can be useful to decouple the parameters to better understand the mechanisms underlying any heat transfer enhancement. Using two-dimensional, two-component particle image velocimetry, the current work intends to characterize the heat transfer mechanisms in pulsating flow with a mean Reynolds number of 48 by experimentally quantifying the hydrodynamics of a generic liquid-cooled channel geometry. Flows circulated through the test section by a gear pump are modulated using a controller to achieve sinusoidal flow pulsations with Womersley numbers of 7.45 and 2.36 and an amplitude ratio of 0.75. It is found that the transient characteristics of the measured velocity profiles are dependent on the speed of oscillation, in accordance with the analytical solution for flow in a rectangular channel. A large velocity overshoot is observed close to the wall at high frequencies, resulting from the interaction of near-wall viscous stresses and inertial effects of the main fluid body. The steep velocity gradients at the wall are indicative of augmented heat transfer, although the local flow reversal may reduce the upstream temperature difference in heat transfer applications. While unsteady effects remain evident at the lower frequency, the annular effect subsides and retreats from the wall. The shear rate at the wall is increased during the accelerating half-cycle and decreased during deceleration compared to steady flow, suggesting that the flow may experience both enhanced and diminished heat transfer during a single period. Hence, the thickness of the hydrodynamic boundary layer is reduced for positively moving flow during one half of the pulsation cycle at the investigated frequencies. It is expected that the size of the thermal boundary layer is similarly reduced during the cycle, leading to intervals of heat transfer enhancement.

Keywords: Heat transfer enhancement, particle image velocimetry, localized and time-resolved velocity, photonics and electronics cooling, pulsating flow, Richardson’s annular effect

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Authors: Emir Borovac, Sedat İnan

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The Silurian Tannezuft Formation within the Ghadames Basin of Northwestern Libya, like other Silurian shales in North Africa and the Middle East, represents a significant prospect for unconventional hydrocarbon exploration. Unlike the more popular and extensively studied Sirt Basin, the Ghadames Basin remains underexplored, presenting untapped potential that warrants further investigation. This study focuses on the thermal maturity and hydrocarbon generation histories of the Tannezuft shales, utilizing calibrated basin modeling approaches. The Tannezuft shales are organic-rich and primarily contain Type II kerogen, especially in the basal layer, which contains up to 10 wt. % TOC, leading to its designation as ‘hot shale’. The research integrates geological, geochemical, and basin modeling data to elucidate the unconventional hydrocarbon potential of this formation, which is crucial given the global demand for energy and the need for new resources. By employing PetroMod software from Schlumberger, calibrated modeling results simulate hydrocarbon generation and migration within the Tannezuft shales. The findings suggest dual-phase hydrocarbon generation from the Lower Silurian Tannezuft source rock, related to deep burial prior to Hercynian orogeny and subsequent Alpine orogeny events. The Ghadames Basin's tectonic history, including major Hercynian and Alpine orogenies, has significantly influenced the generation, migration, and preservation of hydrocarbons, making the Ghadames Basin a promising area for further exploration.

Keywords: tanezzuft formation, ghadames basin, silurian hot shale, unconventional hydrocarbon

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Authors: David M. Gilstrap

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Designing effective instructions is a critical dimension of effective teaching systems. Due to a void in interpersonal contact, online courses present new challenges in this regard, especially with large class sizes. This presentation is a case study in how the repetition of instructions within the course design was utilized to increase instructor efficiency in managing a rapid rise in enrollment. World of Turf is a two-credit, semester-long elective course for non-turfgrass majors at Michigan State University. It is taught entirely online and solely by the instructor without any graduate teaching assistants. Discussion forums about subject matter are designated for each lecture, and those forums are moderated by a few undergraduate turfgrass majors. The instructions as to the course structure, navigation, and grading are conveyed in the syllabus and course-introduction lecture. Regardless, students email questions about such matters, and the number of emails increased as course enrollment grew steadily during the first three years of its existence, almost to a point that the course was becoming unmanageable. Many of these emails occurred because the instructor was failing to update and operate the course in a timely and proper fashion because he was too busy answering emails. Some of the emails did help the instructor ferret out poorly composed instructions, which he corrected. Beginning in the summer semester of 2015, the instructor overhauled the course by segregating content into weekly modules. The philosophy envisioned and embraced was that there can never be too much repetition of instructions in an online course. Instructions were duplicated within each of these modules as well as associated modules for syllabus and schedules, getting started, frequently asked questions, practice tests, surveys, and exams. In addition, informational forums were created and set aside for questions about the course workings and each of the three exams, thus creating even more repetition. Within these informational forums, students typically answer each other’s questions, which demonstrated to the students that that information is available in the course. When needed, the instructor interjects with corrects answers or clarifies any misinformation which students might be putting forth. Increasing the amount of repetition of instructions and strategic enhancements to the course design have resulted in a dramatic decrease in the number of email replies necessitated by the instructor. The resulting improvement in efficiency allowed the instructor to raise enrollment limits thus effecting a ten-fold increase in enrollment over a five-year period with 1050 students registered during the most recent academic year, thus becoming easily the largest online course at the university. Because of the improvement in course-delivery efficiency, sufficient time was created that allowed the instructor to development and launch an additional online course, hence further enhancing his productivity and value in terms of the number of the student-credit hours for which he is responsible.

Keywords: design, efficiency, instructions, online, repetition

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Authors: Deepak Kumar, Debasish Deb, Reena Mamgain

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Radar signal processing requires high number crunching capability. Most often this is achieved using multiprocessor platform. Though multiprocessor platform provides the capability of meeting the real time computational challenges, the architecture of the same along with mapping of the algorithm on the architecture plays a vital role in efficiently using the platform. Towards this, along with standard performance metrics, few additional metrics are defined which helps in evaluating the multiprocessor platform along with the algorithm mapping. A generic multiprocessor architecture can not suit all the processing requirements. Depending on the system requirement and type of algorithms used, the most suitable architecture for the given problem is decided. In the paper, we study different architectures and quantify the different performance metrics which enables comparison of different architectures for their merit. We also carried out case study of different architectures and their efficiency depending on parallelism exploited on algorithm or data or both.

Keywords: radar signal processing, multiprocessor architecture, efficiency, load imbalance, buffer requirement, pipeline, parallel, hybrid, cluster of processors (COPs)

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Authors: Suphalucksana, Wichai, Sangsoponjit Settasit, Soytong Kasem

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A study on the efficiency for enzyme production of fungi isolated from stomach of buffalo was conducted. The fungi were collected from 4 parts of stomach as rumen, reticulum, omasum and abomasums. The objective to study the efficiency of fungi from stomach of buffalo had effected to produced enzyme and to selected fungi for their ability to produced enzyme cellulase, hemicellulase and ligninase. Results shown that the fungi isolated from rumen were: Eupenicillium sp. (B-RU-01-1), Eupenicillium sp. (B-RU-02-3G), Rhyzopus stolonifer (B-RU-01-4) and Trichoderma sp. (B-RU-01-2). From the reticulum, Aspergillus glaucus (B-RET-02-3), Aspergillus orchraceus (B-RET-02-2) and Penicillium sp. (B-RET-02-4) were found. In the omasum Aspergillus fumigatus (B-OMA-01-1G), Eurotium sp. (B-OMA-01-4) and Rhizopus stolonifer (B-OMA-02-3) were isolated and in the abomasums Aspergillus flavas (B-ABO-02-3), Aspergillus fumigatus (B-ABO-02-1), Aspergillus niger (B-ABO-01-3G), Aspergillius terreus (B-ABO-02-4) and Mucor sp. (B-ABO-02-4G). Results of enzyme analysis revealed that cellulase was produced by isolated: Eupenicillium sp. (B-RU-02-3G), Eupenicillium sp. (B-RU-01-1), Penicillium sp. (B-RET-02-4), Aspergillius glaucus (B-RET-02-3), Aspergillus ochraceus (B-RET-02-2), Aspergillius fumigatus (B-OMA-01-1G), Eurotium sp. (B-OMA-01-4), Aspergillius flavus (B-ABO-02-3), Aspergillius fumigatus (B-ABO-02-1), Aspergillius niger (B-ABO-01-3G), Aspergillius terreus (B-ABO-02-4). Hemicellulase was produced Eupenicillium sp. (B-RU-02-3G), Eupenicillium sp. (B-RU-01-1), Rhizopus stolonifer (B-RU-01-4), Trichoderma sp. (B-RU-01-2), Aspergillius glaucus (B-RET-02-3), Aspergillus ochraceus (B-RET-02-2), Penicillium sp. (B-RET-02-4), Aspergillius fumigatus (B-OMA-01-1G), Eurotium sp. (B-OMA -01-4), Aspergillius flavus (B-ABO-02-3), Aspergillius fumigatus (B-ABO-02-1) Aspergillius niger (B-ABO-01-3G), Aspergillius terreus (B-ABO-02-4), Mucor sp. (B-ABO-02-4G). For the enzyme ligninase, two isolates were found to produced this enzyme namely : Trichoderma sp. (B-RU-01-2) and Mucor sp. (B-ABO-02-4G).

Keywords: enzyme production from fungi, enzyme production, fungi, agricultural technology

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Authors: Denis Ushakov

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Fast growing international migration as a factor of labor globalization now is one of the most important trends of world economy and determinant of social-political transformations. Study of fundamental economical reasons for international migration is relevant due to their prognostic, predictable and normative potential, which can be used in conditions of global economic non-stability. This paper analyzes role of natural-resources, financial and labor factors in economic growth of the modern states; studies relationships between stimulating role of natural resources, finance and labor with levels of modern countries’ economy development. Based on achieved results, findings about fundamental reasons of international migration; transformation of labor factor’s role in providing an economical progress of the states; efficiency of positive impact of manufacturing factors (domestic and attracted from international markets) were offered.

Keywords: international migration, migrant, labor productivity, economy efficiency of migration, migration policy

Procedia PDF Downloads 269

Authors: Y. Mateyshina, A.Ulihin, N.Uvarov

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Electrolytes with different type of charge carrier can find widely application in different using, e.g. sensors, electrochemical equipments, batteries and others. One of important components ensuring stable functioning of the equipment is electrolyte. Electrolyte has to be characterized by high conductivity, thermal stability, and wide electrochemical window. In addition to many advantageous characteristic for liquid electrolytes, the solid state electrolytes have good mechanical stability, wide working range of temperature range. Thus search of new system of solid electrolytes with high conductivity is an actual task of solid state chemistry. Families of alkali perchlorates and nitrates have been investigated by us earlier. In literature data about transport properties of alkali nitrites are absent. Nevertheless, alkali nitrites MeNO2 (Me= Li+, Na+, K+, Rb+ and Cs+), except for the lithium salt, have high-temperature phases with crystal structure of the NaCl-type. High-temperature phases of nitrites are orientationally disordered, i.e. non-spherical anions are reoriented over several equivalents directions in the crystal lattice. Pure lithium nitrite LiNO2 is characterized by ionic conductivity near 10-4 S/cm at 180°C and more stable as compared with lithium nitrate and can be used as a component for synthesis of composite electrolytes. In this work composite solid electrolytes in the binary system LiNO2 - A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) were synthesized and their structural, thermodynamic and electrical properties investigated. Alkali nitrite was obtained by exchange reaction from water solutions of barium nitrite and alkali sulfate. The synthesized salt was characterized by X-ray powder diffraction technique using D8 Advance X-Ray Diffractometer with Cu K radiation. Using thermal analysis, the temperatures of dehydration and thermal decomposition of salt were determined.. The conductivity was measured using a two electrode scheme in a forevacuum (6.7 Pa) with an HP 4284A (Precision LCR meter) in a frequency range 20 Hz < ν < 1 MHz. Solid composite electrolytes LiNO2 - A A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) have been synthesized by mixing of preliminary dehydrated components followed by sintering at 250°C. In the series of nitrite of alkaline metals Li+-Cs+, the conductivity varies not monotonically with increasing radius of cation. The minimum conductivity is observed for KNO2; however, with further increase in the radius of cation in the series, the conductivity tends to increase. The work was supported by the Russian Foundation for Basic research, grant #14-03-31442.

Keywords: conductivity, alkali nitrites, composite electrolytes, transport properties

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Authors: Mohammad Ali Rajaeifar, Oliver Heidrich

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Nowadays, Li-ion batteries are vastly disseminated and the battery market is expected to experience a huge growth during next decade especially in terms of traction batteries. As the automotive industry moving towards the electrification of the powertrain, more raw/critical materials and energy are extracted while on the other hand, concerns are made regarding the scarcity of the materials as well as environmental issues regarding the destiny of the spent batteries. In this regards, recycling could play a vital role in the supply chain, leading reutilization of key battery materials and also reducing environmental burden related to the use of batteries. The aim of this paper is to review the previous and state-of-the-art treatments for recycling of Li-ion batteries. All the treatments method from mechanical, mild-thermal, pyrometallurgical and hydrometallurgical as well as combined methods for recycling of Li-ion batteries were considered in the study. There are various treatment methods that are economical, but they are not environmentally friendly or vice versa. This is due to the fact that the benefits of the Li-ion batteries recycling could be affected by different factors such as the amount of spent batteries available, the quality of the recovered material, the energy and material consumption by the process itself and environmental burdens caused by required logistics. Finally, a preliminary work sheet of possible route for recycling of spent Li-ion batteries was presented through the course of this study. Overall, it is worth quoting that recycling processes generally consumes a great deal of energy and auxiliary materials. Moreover, the collection of spent products from waste streams represents additional environmental efforts. Therefore, developing and optimizing efficient collection and separation technologies is essential to achieve sustainability goals.

Keywords: hydrometallurgical treatment, Li-ion batteries, mild-thermal treatment, mechanical treatment, recycling, pyrometallurgical treatment

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Authors: Júlia Cristina Bonaldo, Christophe L. Martin, Martiniano Piccico, Keith Beale, Roop Kishore, Severine Romero-Baivier

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Refractory composite materials employed in steel casting applications are prone to cracking and material damage because of the very high operating temperature (thermal shock) and mismatched properties of the constituent phases. The fracture behavior of a model MgO-C composite refractory is investigated to quantify and characterize its thermal shock resistance, employing a cold crushing test and Brazilian test with fractographic analysis. The discrete element method (DEM) is used to generate numerical refractory composites. The composite in DEM is represented by an assembly of bonded particle clusters forming perfectly spherical aggregates and single spherical particles. For the stresses to converge with a low standard deviation and a minimum number of particles to allow reasonable CPU calculation time, representative volume element (RVE) numerical packings are created with various numbers of particles. Key microscopic properties are calibrated sequentially by comparing stress-strain curves from crushing experimental data. Comparing simulations with experiments also allows for the evaluation of crack propagation, fracture energy, and strength. The crack propagation during Brazilian experimental tests is monitored with digital image correlation (DIC). Simulations and experiments reveal three distinct types of fracture. The crack may spread throughout the aggregate, at the aggregate-matrix interface, or throughout the matrix.

Keywords: refractory composite, fracture mechanics, crack propagation, DEM

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Authors: Bernice Jeanne Lottering, Yi-Wen Lin

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Introduction: Chronic pain has a definitive lack of objective parameters in the measurement and treatment efficacy of diseases such as Fibromyalgia (FM). Persistent widespread pain and generalized tenderness are the characteristic symptoms affecting a large majority of the global population, particularly females. This disease has indicated a refractory tendency to conventional treatment ventures, largely resultant from a lack of etiological and pathogenic understanding of the disease development. Emerging evidence indicates that the central nervous system (CNS) plays a critical role in the amplification of pain signals and the neurotransmitters associated therewith. Various stimuli have been found to activate the channels existent on nociceptor terminals, thereby actuating nociceptive impulses along the pain pathways. The transient receptor potential vanalloid 1 (TRPV1) channel functions as a molecular integrator for numerous sensory inputs, such as nociception, and was explored in the current study. Current intervention approaches face a multitude challenges, ranging from effective therapeutic interventions to the limitation of pathognomonic criteria resultant from incomplete understanding and partial evidence on the mechanisms of action of FM. It remains unclear whether electroacupuncture (EA) plays an integral role in the functioning of the TRPV1 pathway, and whether or not it can reduce the chronic pain induced by FM. Aims: The aim of this study was to explore the mechanisms underlying the activation and modulation of the TRPV1 channel pathway in a cold stress model of FM applied to a murine model. Furthermore, the effect of EA in the treatment of mechanical and thermal pain, as expressed in FM was also to be investigated. Methods: 18 C57BL/6 wild type and 6 TRPV1 knockout (KO) mice, aged 8-12 weeks, were exposed to an intermittent cold stress-induced fibromyalgia-like pain model, with or without EA treatment at ZusanLi ST36 (2Hz/20min) on day 3 to 5. Von Frey and Hargreaves behaviour tests were implemented in order to analyze the mechanical and thermal pain thresholds on day 0, 3 and 5 in control group (C), FM group (FM), FM mice with EA treated group (FM + EA) and FM in KO group. Results: An increase in mechanical and thermal hyperalgesia was observed in the FM, EA and KO groups when compared to the control group. This initial increase was reduced in the EA group, which directs focus at the treatment efficacy of EA in nociceptive sensitization, and the analgesic effect EA has attenuating FM associated pain. Discussion: An increase in the nociceptive sensitization was observed through higher withdrawal thresholds in the von Frey mechanical test and the Hargreaves thermal test. TRPV1 function in mice has been scientifically associated with these nociceptive conduits, and the increased behaviour test results suggest that TRPV1 upregulation is central to the FM induced hyperalgesia. This data was supported by the decrease in sensitivity observed in results of the TRPV1 KO group. Moreover, the treatment of EA showed a decrease in this FM induced nociceptive sensitization, suggesting TRPV1 upregulation and overexpression can be attenuated by EA at bilateral ST36. This evidence compellingly implies that the analgesic effect of EA is associated with TRPV1 downregulation.

Keywords: fibromyalgia, electroacupuncture, TRPV1, nociception

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Authors: Jens-Phillip Petersen

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The reduction of GHG emissions in buildings is a focus area of national energy policies in Europe, because buildings are responsible for a major share of the final energy consumption. It is at local scale where policies to increase the share of renewable energies and energy efficiency measures get implemented. Municipalities, as local authorities and responsible entity for land-use planning, have a direct influence on urban patterns and energy use, which makes them key actors in the transition towards sustainable cities. Hence, synchronizing urban planning with energy planning offers great potential to increase society’s energy-efficiency; this has a high significance to reach GHG-reduction targets. In this paper, the actual linkage of urban planning and energy planning in Denmark and Germany was assessed; substantive barriers preventing their integration and driving factors that lead to successful transitions towards a holistic urban energy planning procedures were identified.

Keywords: energy planning, urban planning, renewable energies, sustainable cities

Procedia PDF Downloads 342

Authors: Muhammad Abid

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In this study, we performed the comparative exergetic and exergoeconomic analyses of a wind turbine over a period of twelve months from 1st January to 30th December 2011. The turbine is part of a wind-PV hybrid system with hydrogen storage, located on the roof of Mechanical Engineering Department, King Saud University, Riyadh, Saudi Arabia. The rated power output from this turbine is 1.7 W with a rated wind speed of 12 m/s and cut-in/cut-out wind speeds of 3/14 m/s. We utilize a wide range of experimental data in the analysis and assessment. We determine exergy efficiencies and their relation with meteorological variables, such as temperature and density. We also calculate exergoeconomic parameter R ̇_ex and its dependence on the temperature, using the average values for twelve months of the year considered for comparison purposes. The exergy efficiency changes from 0.12 to 0.31 while the density varies between 1.31 and 1.2 kg/m3 for different temperature values. The R ̇_ex has minimum and maximum values of 0.02 and 0.81, respectively, while the temperature is in the range of 8-24°C for various wind velocity values.

Keywords: exergy, efficiency, renewable energy, wind energy, meteorological variables

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Authors: Nadish Anand, Richard D. Gould

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A simplistic model is introduced for determining the thermal characteristics of a Low-rise Residential (LRR) building and then predicts the energy usage by its Heating Ventilation & Air Conditioning (HVAC) system according to changes in weather conditions which are reflected in the Ambient Temperature (Outside Air Temperature). The LRR buildings are treated as a simple lump for solving the heat transfer problem and the model is derived using the lumped capacitance model of transient conduction heat transfer from bodies. Since most contemporary HVAC systems have a thermostat control which will have an offset temperature and user defined set point temperatures which define when the HVAC system will switch on and off. The aim is to predict without any error the Body Temperature (i.e. the Inside Air Temperature) which will estimate the switching on and off of the HVAC system. To validate the mathematical model derived from lumped capacitance we have used EnergyPlus simulation engine, which simulates Buildings with considerable accuracy. We have predicted through the low order model the Inside Air Temperature of a single house kept in three different climate zones (Detroit, Raleigh & Austin) and different orientations for summer and winter seasons. The prediction error from the model for the same day as that of model parameter calculation has showed an error of < 10% in winter for almost all the orientations and climate zones. Whereas the prediction error is only <10% for all the orientations in the summer season for climate zone at higher latitudes (Raleigh & Detroit). Possible factors responsible for the large variations are also noted in the work, paving way for future research.

Keywords: building energy, energy consumption, energy+, HVAC, low order model, lumped capacitance

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Authors: Redouane Lombarkia

Abstract:

To apply a new material model developed and validated for plain weave fabric CFRP composites usually used in stanchions in sub-cargo section in aircrafts. This work deals with the development of a numerical model of the fuselage section of commercial aircraft based on the pure explicit finite element method FEM within Abaqus/Explicit commercial code. The aim of this work is the evaluation of the energy absorption capabilities of a full-scale composite fuselage section, including sub-cargo stanchions, Drop tests were carried out from a free fall height of about 5 m and impact velocity of about 6 m∕s. To asses, the prediction efficiency of the proposed numerical modeling procedure, a comparison with literature existed experimental results was performed. We demonstrate the efficiency of the proposed methodology to well capture crash damage mechanisms compared to experimental results

Keywords: crashworthiness, fuselage section, finite elements method (FEM), stanchions, specific energy absorption SEA

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Authors: Marta Błażkiewicz-Mazurek, Adam Konefał

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The project can be divided into three main parts: i. modeling the Cf-252 neutron source and conducting an experiment to verify the correctness of the obtained results, ii. design of the BNCT system infrastructure, iii. analysis of the results from the logical detector. Modeling of the Cf-252 source included designing the shape and size of the source as well as the energy and spatial distribution of emitted neutrons. Two options were considered: a point source and a cylindrical spatial source. The energy distribution corresponded to various spectra taken from specialized literature. Directionally isotropic neutron emission was simulated. The simulation results were compared with experimental values determined using the activation detector method using indium foils and cadmium shields. The relative fluence rate of thermal and resonance neutrons was compared in the chosen places in the vicinity of the source. The second part of the project related to the modeling of the BNCT infrastructure consisted of developing a simulation program taking into account all the essential components of this system. Materials with moderating, absorbing, and backscattering properties of neutrons were adopted into the project. Additionally, a gamma radiation filter was introduced into the beam output system. The analysis of the simulation results obtained using a logical detector located at the beam exit from the BNCT infrastructure included neutron energy and their spatial distribution. Optimization of the system involved changing the size and materials of the system to obtain a suitable collimated beam of thermal neutrons.

Keywords: BNCT, Monte Carlo, neutrons, simulation, modeling

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Authors: Markus Rütten, Olaf Wünsch

Abstract:

Non-Newtonian fluid properties can change the flow behaviour significantly, its prediction is more difficult when thermal effects come into play. Hence, the focal point of this work is the wake flow behind a heated circular cylinder in the laminar vortex shedding regime for thermo-viscous shear thinning fluids. In the case of isothermal flows of Newtonian fluids the vortex shedding regime is characterised by a distinct Reynolds number and an associated Strouhal number. In the case of thermo-viscous shear thinning fluids the flow regime can significantly change in dependence of the temperature of the viscous wall of the cylinder. The Reynolds number alters locally and, consequentially, the Strouhal number globally. In the present CFD study the temperature dependence of the Reynolds and Strouhal number is investigated for the flow of a Carreau fluid around a heated cylinder. The temperature dependence of the fluid viscosity has been modelled by applying the standard Williams-Landel-Ferry (WLF) equation. In the present simulation campaign thermal boundary conditions have been varied over a wide range in order to derive a relation between dimensionless heat transfer, Reynolds and Strouhal number. Together with the shear thinning due to the high shear rates close to the cylinder wall this leads to a significant decrease of viscosity of three orders of magnitude in the nearfield of the cylinder and a reduction of two orders of magnitude in the wake field. Yet the shear thinning effect is able to change the flow topology: a complex K´arm´an vortex street occurs, also revealing distinct characteristic frequencies associated with the dominant and sub-dominant vortices. Heating up the cylinder wall leads to a delayed flow separation and narrower wake flow, giving lesser space for the sequence of counter-rotating vortices. This spatial limitation does not only reduce the amplitude of the oscillating wake flow it also shifts the dominant frequency to higher frequencies, furthermore it damps higher harmonics. Eventually the locally heated wake flow smears out. Eventually, the CFD simulation results of the systematically varied thermal flow parameter study have been used to describe a relation for the main characteristic order parameters.

Keywords: heat transfer, thermo-viscous fluids, shear thinning, vortex shedding

Procedia PDF Downloads 295

Authors: Chalermporn Jindapeng

Abstract:

The main objective of the study of the suitable operating conditions of hot water generators combined with central air package units: a case study of Tipco Building Group was to analyze the suitable operating conditions and energy-related costs in each operating condition of hot water generators combined with central air package units which resulted in water-cooled packages. Thermal energy from vapor form refrigerants at high pressures and temperatures was exchanged with thermal energy of the water in the swimming pool that required suitable temperature control for users with the use of plate heat exchangers before refrigerants could enter the condenser in its function to change the status of vapor form refrigerants at high pressures and temperatures to liquid form at high pressures and temperatures. Thus, if this was used to replace heat pumps it could reduce the electrical energy that was used to make hot water and reduce the cost of the electrical energy of air package units including the increased efficacy of air package units. Of the analyses of the suitable operating conditions by means of the study of the elements involved with actual measurements from the system that had been installed at the Tipco Building Group hot water generators were combined with air package units which resulted in water-cooled packages with a cooling capacity of 75 tonnes. Plate heat exchangers were used in the transfer of thermal energy from refrigerants to one set of water with a heat exchanger area of 1.5 m² which was used to increase the temperature of swimming pool water that has a capacity of 240 m³. From experimental results, it was discovered after continuous temperature measurements in the swimming pool every 15 minutes that swimming pool water temperature increased by 0.78 ⁰C 0.75 ⁰C 0.74 ⁰C and 0.71 ⁰C. The rates of flow of hot water through the heat exchangers were equal to 14, 16, 18 and 20 litres per minute respectively where the swimming pool water temperature was at a constant value and when the rate of flow of hot water increased this caused hot water temperatures to decrease and the coefficient of performance of the air package units to increase from 5.9 to 6.3, 6.7, 6.9 and 7.6 while the rates of flow of hot water were equal to 14, 16, 18 and 20 litres per minute, respectively. As for the cooling systems, there were no changes and the system cooling functions were normal as the cooling systems were able to continuously transfer incoming heat for the swimming pool water which resulted in a constant pressure in the cooling system that allowed its cooling functions to work normally.

Keywords: central air package units, heat exchange, hot water generators, swimming pool

Procedia PDF Downloads 255

Authors: Luiz Carlos Wrobel, Matjaz Hribersek, Jure Marn, Jurij Iljaz

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Dynamic thermography has been clinically proven to be a valuable diagnostic technique for skin tumor detection as well as for other medical applications such as breast cancer diagnostics, diagnostics of vascular diseases, fever screening, dermatological and other applications. Thermography for medical screening can be done in two different ways, observing the temperature response under steady-state conditions (passive or static thermography), and by inducing thermal stresses by cooling or heating the observed tissue and measuring the thermal response during the recovery phase (active or dynamic thermography). The numerical modelling of heat transfer phenomena in biological tissue during dynamic thermography can aid the technique by improving process parameters or by estimating unknown tissue parameters based on measured data. This paper presents a nonlinear numerical model of multilayer skin tissue containing a skin tumor, together with the thermoregulation response of the tissue during the cooling-rewarming processes of dynamic thermography. The model is based on the Pennes bioheat equation and solved numerically by using a subdomain boundary element method which treats the problem as axisymmetric. The paper includes computational tests and numerical results for Clark II and Clark IV tumors, comparing the models using constant and temperature-dependent thermophysical properties, which showed noticeable differences and highlighted the importance of using a local thermoregulation model.

Keywords: boundary element method, dynamic thermography, static thermography, skin tumor diagnostic

Procedia PDF Downloads 100

Authors: A. Nour Eddine, D. Chalet, L. Aixala, P. Chessé, X. Faure, N. Hatat

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Thermal power technology such as the TEG (Thermo-Electric Generator) arouses significant attention worldwide for waste heat recovery. Despite the potential benefits of marine application due to the permanent heat sink from sea water, no significant studies on this application were to be found. In this study, a test rig has been designed and built to test the performance of the TEG on engine operating points. The TEG device is built from commercially available materials for the sake of possible economical application. Two types of commercial TEM (thermo electric module) have been studied separately on the test rig. The engine data were extracted from a commercial Diesel engine since it shares the same principle in terms of engine efficiency and exhaust with the marine Diesel engine. An open circuit water cooling system is used to replicate the sea water cold source. The characterization tests showed that the silicium-germanium alloys TEM proved a remarkable reliability on all engine operating points, with no significant deterioration of performance even under sever variation in the hot source conditions. The performance of the bismuth-telluride alloys was 100% better than the first type of TEM but it showed a deterioration in power generation when the air temperature exceeds 300 °C. The temperature distribution on the heat exchange surfaces revealed no useful combination of these two types of TEM with this tube length, since the surface temperature difference between both ends is no more than 10 °C. This study exposed the perspective of use of TEG technology for marine engine exhaust heat recovery. Although the results suggested non-sufficient power generation from the low cost commercial TEM used, it provides valuable information about TEG device optimization, including the design of heat exchanger and the types of thermo-electric materials.

Keywords: internal combustion engine application, Seebeck, thermo-electricity, waste heat recovery

Procedia PDF Downloads 241

Authors: Ayman M. El-Zahaby, Ahmed S. El-Gendy

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Aeration for wastewater is essential for the proper operation of aerobic treatment units where the wastewater normally has zero dissolved oxygen. This is due to the need of oxygen by the aerobic microorganisms to grow and survive. Typical aeration units for wastewater treatment require electric energy for their operation such as mechanical aerators or diffused aerators. The passive units are units that operate without the need of electric energy such as cascade aerators, spray aerators and tray aerators. In contrary to the cascade aerators and spray aerators, tray aerators require much smaller area foot print for their installation as the treatment stages are arranged vertically. To the extent of the authors knowledge, the design of tray aerators for the aeration purpose has not been presented in the literature. The current research concerns with an analytical study for the design of tray aerators for the purpose of increasing the dissolved oxygen in wastewater treatment systems, including an investigation on different design parameters and their impact on the aeration efficiency. The studied aerator shall act as an intermediate stage between an anaerobic primary treatment unit and an aerobic treatment unit for small scale treatment systems. Different free falling flow regimes were investigated, and the thresholds for transition between regimes were obtained from the literature. The study focused on the jetting flow regime between trays. Starting from the two film theory, an equation that relates the dissolved oxygen concentration effluent from the system was derived as a function of the flow rate, number of trays, tray area, spacing between trays, number and diameter of holes and the water temperature. A MATLab ® model was developed for the derived equation. The expected aeration efficiency under different tray configurations and operating conditions were illustrated through running the model with varying the design parameters. The impact of each parameter was illustrated. The overall system efficiency was found to increase by decreasing the hole diameter. On the other side, increasing the number of trays, tray area, flow rate per hole or tray spacing had positive effect on the system efficiency.

Keywords: aeration, analytical, passive, wastewater

Procedia PDF Downloads 204

Authors: Laura Dembovska, Diana Bajare, Ina Pundiene, Daira Erdmane

Abstract:

The aim of this research is to estimate effect of pozzolanic substitutes and their combination on the hydration heat and final strength of high performance concrete. Ternary cementitious systems with different ratios of ordinary Portland cement, silica fume and calcined clay were investigated. Local illite clay was calcined at temperature 700oC in rotary furnace for 20 min. It has been well recognized that the use of pozzolanic materials such as silica fume or calcined clay are recommended for high performance concrete for reduction of porosity, increasing density and as a consequence raising the chemical durability of the concrete. It has been found, that silica fume has a superior influence on the strength development of concrete, but calcined clay increase density and decrease size of dominating pores. Additionally it was found that the rates of pozzolanic reaction and calcium hydroxide consumption in the silica fume-blended cement pastes are higher than in the illite clay-blended cement pastes, it strongly depends from the amount of pozzolanic substitutes which are used. If the pozzolanic reaction is dominating then amount of Ca(OH)2 is decreasing. The identity and the amount of the phases present were determined from the thermal analysis (DTA) data. The hydration temperature of blended cement pastes was measured during the first 24 hours. Fresh and hardened concrete properties were tested. Compressive strength was determined and differential thermal analysis (DTA) was conducted of specimens at the age of 3, 14, 28 and 56 days.

Keywords: high performance concrete, pozzolanic additives, silica fume, ternary systems

Procedia PDF Downloads 371

Authors: S. Naderizadeh, A. Athanassiou, I. S. Bayer

Abstract:

This work describes a layer-by-layer spraying method to produce a non-wetting coating, based on thermoplastic polyurethane (TPU) and silica nanoparticles (Si-NPs). The main purpose of this work was to transform a hydrophilic polymer to superhydrophobic coating. The contact angle of pure TPU was measured about 77˚ ± 2, and water droplets did not roll away upon tilting even at 90°. But after applying a layer of Si-NPs on top of this, not only the contact angle increased to 165˚ ± 2, but also water droplets can roll away even below 5˚ tilting. The most important restriction in this study was the weak interfacial adhesion between polymer and nanoparticles, which had a bad effect on durability of the coatings. To overcome this problem, we used a very thin layer of graphene nanoplatelets (GNPs) as an interlayer between TPU and Si-NPs layers, followed by thermal treatment at 150˚C. The sample’s morphology and topography were characterized by scanning electron microscopy (SEM), EDX analysis and atomic force microscopy (AFM). It was observed that Si-NPs embedded into the polymer phase in the presence of GNPs layer. It is probably because of the high surface area and considerable thermal conductivity of the graphene platelets. The contact angle value for the sample containing graphene decreased a little bit respected to the coating without graphene and reached to 156.4˚ ± 2, due to the depletion of the surface roughness. The durability of the coatings against abrasion was evaluated by Taber® abrasion test, and it was observed that superhydrophobicity of the coatings remains for a longer time, in the presence of GNPs layer. Due to the simple fabrication method and good durability of the coating, this coating can be used as a durable superhydrophobic coating for metals and can be produced in large scale.

Keywords: graphene, silica nanoparticles, superhydrophobicity, thermoplastic polyurethane

Procedia PDF Downloads 177