Download or read book Computational Analysis of Nanostructures Formed in Molten Salt Nanofluids written by Vidula B. Pawar and published by . This book was released on 2015 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Meeting the continuously increasing demand of 'clean' energy is the biggest challenge of the energy research field. Amongst the many renewable sources of energy, energy from the Sun is one of the biggest sources in the form of light and heat. Photovoltaic cells and concentrated solar power are few of the solar energy harnessing technologies. Photovoltaic cells use semiconductor materials to directly convert energy from sun into electricity. CSP uses a combination of solar receivers (mirrors or lenses) to concentrate the solar thermal energy which is further converted into electricity using the common thermodynamic cycle. One of the Photovoltaic (PV) technology's disadvantages over CSP is that it delivers power only in direct sunlight and it cannot store excess amounts of produced energy for later use. This is overcome by CSP. Thermal energy storage (TES) devices are used in CSP which store large amount of thermal energy for later use. TES use organic materials like paraffin wax, synthetic oils etc. as their heat transfer fluids (HTF). One of the drawbacks of CSP technology is the limiting operating temperatures of HTF (up to 400 °C), which affects the theoretical thermal efficiency. Increasing this operating temperature up to 560 °C, which is the creeping temperature of stainless steel, can enhance the efficiency (from 54% to 63%). Hence, the uses of molten salts, which are thermally stable up to 600 °C, have been proposed to use as TES. With advantages of high operating temperature, low cost and environmentally safe these salts have disadvantage of poor thermo-physical properties like low specific heat capacity and thermal conductivity. A lot of experimental results of enhancements in the thermo-physical properties of molten-salt embedded with nanofluids have been reported. Nanofluids are solvents doped with nanoparticles. These reports suggest formation of nanostructures with liquid layer separations in the base salts as possible cause of enhancements. But there has been very limited computational analysis study to support these findings. Tiznobaik et al saw nanostructure formed near nanoparticles and concluded it to be the primary cause for the enhanced specific heat capacity in carbonate nanofluids, (Li2CO3-K2CO3/SiO2). The formation of nanostructure was reasoned with dense layers and concentration gradient seen within the surrounding molten salt mixture. In this study an attempt has been made to elucidate and support this finding using computational analysis. Molecular Dynamic simulations have been performed using LAMMPS to analyze the cause of nanostructure formations. For the simulation, a periodic box of Li2CO3-K2CO3 (62:38) and a SiO2 nanocluster was made in Material Studio. After lot of initializations, a stable system was achieved and analysis showed concentration gradient around the nanocluster. Same analysis will help to prove the theory of concentration gradient in other combination of salts and nanomaterials. This will also act as a base for finding the thermo-physical properties like heat capacity, thermal conductivity, density etc. of such salts to further validate the experimental results showing their enhancements.

Download or read book Investigation of Thermo physical Property Enhancement Mechanism of Molten Salt Nano eutectic Via Nanostructural Change and Polyalphaolefin Nanofluid Via in Situ Formation of Superstructures written by Zahra Pournorouz and published by . This book was released on 2019 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: For many years, scientists enhanced the specific heat capacity of molten salt nanofluids by dispersing only minute concentrations of different nanoparticles (e.g., 1 wt.%). While the specific heat capacity for molten salts was enhanced in many types of research, other engineering fluids (i.e., water, ethylene glycol, oil) showed decreased specific heat capacity with doping the nanoparticles. Recently, researchers discovered that a unique nanostructure formed by molten salt molecules, which were doped and interacted with nanoparticles, were the reason for enhanced specific heat capacity. Therefore, the enhanced specific heat capacity only happens for molten salts rather than other fluids that may not naturally form these nanostructures. In the first study, the specific heat capacity of molten salt nano-eutectic (??2??3 − ?2??3 doped with ???2 nanoparticles) was theoretically investigated. Corresponding to the proposed theory in the literature [1], the specific heat capacity of a nano-eutectic can be significantly increased by the formation of needle-like nanostructures by salt eutectic. To investigate the effect of the formed nanostructure, the model presented by Wang [2] for nano-sized particles was used and expanded to theoretically calculate the specific heat capacity of the nanostructure of molten salt nano-eutectic. The mass fraction of the formed nanostructure was estimated by MATLAB using the reported material characterization study [3]. The theoretical predictions were in a good agreement with the measured specific heat capacity values from the literature, with the error of 3 - 4%. An additional verification of the proposed model was done by a different lab partner using a molecular dynamics study. The error between the theoretical prediction and the simulation is only 3.4%, and the value was in a good agreement with the experiment (1.9% max. error) [66]. The result confirms the enhanced specific heat capacity of a nano-eutectic can be described by the contribution of the formed nanostructure. Hence, we artificially fabricated similar nanostructures and dispersed them in a non-salt medium to see whether it enhances specific heat capacity or not. In the second study, we theorized such nanostructures could be mimicked through the in-situ formation of fabricated nano-additives, which are the acknowledged nanoparticles coated by organic materials (e.g., polar-group-ended organic molecules) resulting to these structures called superstructures. We first portrayed this approach by studying the polyalphaolefin (PAO) oil as the base fluid and coated the ???2 nanoparticles with Polyethylene-block-poly (ethyleneglycol) (PBP). A differential scanning calorimeter (DSC) device, a discovery hybrid rheometer (HR-2), and an in-lab built thermal conductivity apparatus were used to conduct measurements for the specific heat capacity, thermal conductivity, and viscosity of pure PAO and PAO with fabricated nano-additives. Results showed 44.5% enhancement for specific heat capacity and 19.8% and 22.98% enhancement for thermal conductivity and viscosity, respectively, by adding fabricated superstructures compared to pure PAO. Furthermore, a peak representing the partial melting of the PBP was detected in the first thermal cycle, which disappeared in the following cycles; so, this specifies that the in-situ formation of fabricated nano-additives spontaneously happens in the thermal cycle to form such superstructures. At last, we analyzed the figure of merit for PAO-superstructure to evaluate the value of its performance for heat transfer and storage media.

Download or read book Enhanced Specific Heat of Molten Salt Nanofluids written by Hani Tiznobaik and published by . This book was released on 2019 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentrated solar power uses general thermodynamic cycles (such as Rankine or Gas turbine cycle) to produce electricity and thus its efficiency primarily relies on the operating temperature of thermal energy storage. Current thermal energy storage medium is organic material such as synthetic oil or fatty acid. However, these materials are not stable at high temperatures due to their thermal decomposition. Using molten salts as thermal energy storage medium is a very attractive option since they are thermally stable at high temperatures (over 600 °C). They also have very lower vapor pressure (for reducing mechanical stress on structure materials), less reactive, and abundant in nature in comparison with the conventional thermal energy storage materials. However, their low specific heat hinders the use of molten salts as thermal energy storage materials. The low specific heat of molten salts can be enhanced by doping with nanoparticles. Solvents doped with nanoparticles (termed as nanofluids) are well known for their large enhancement of thermal conductivity. In this study, the low specific heat of molten salts were enhanced by doping with nanoparticles. SiO2 nanoparticles were dispersed in a mixture of Li2CO3-K2CO3 at 1% concentration by weight showed 25% enhanced specific heat. From the subsequent material characterization study, a large amount of special fractal-like nanostructures was observed all over the nanofluids. Four different sizes of nanoparticles were tested to prepare nanofluids to verify the effect of nanoparticles on specific heat and the result showed almost no variation in specific heat with nanoparticle size. This implies that nanoparticles may not have direct effect on the enhanced specific heat but may help the formation of the fractal-like nanostructures. The fractal-like nanostructures are formed by molten salt molecules electrostatically interacting with nearby nanoparticles and may be responsible for the enhanced specific heat of nanofluids. To verify this, two batches of nanofluids were prepared and one was treated with a very small amount of hydroxide to interrupt the proposed electrostatic interaction. The result showed that the one treated with hydroxide did not form the fractal-like nanostructures and no specific heat enhancement was observed, while the other nanofluid showed constant 25 % enhanced specific heat. In order to have a better understanding of the effects of the formed nanostructures in nanofluid sample, the rheological properties of the pure and nanofluid samples were studied. The results shows increase not only in the average value of viscosity on the nanofluid sample, but also changing in the behavior of the fluids. That is, the nanofluid samples shows high amount of non-Newtonian behavior compare to the one of pure samples which shows Newtonian behavior. Based on the experimental results, and applying proposed theories to have a better understanding of thermophysical properties of nanostructures, this study proposes a new specific heat mechanism theories of molten salt. A comparison study was conducted using the proposed mechanism to explain the difference between conventional nanofluids whose specific heat decreases and molten salt-based nanofluids whose specific heat increases. The result of this study is expected to not only help to design advanced thermal energy storage for concentrated solar power applications but also help to answer unsolved questions in the field of nanofluids.

Download or read book Modeling and Simulation of Nanofluid for Heat Storage written by Yatish Nagaraj and published by . This book was released on 2015 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work models the dynamic behavior of molten nitrate salt mixture to investigate the formation of interfacial nanostructures in ionic liquid nanofluids which is responsible for increase of heat capacity of the mixture. A key application of these fluids is in heat storage in solar collector where the heat capacity determines the amount of energy storage and therefore the e ciency of a solar collector system. The heat capacity can be significantly increased by the addition of a small amount of nanoparticles, of radius 1 to 100 nanometers in a concentration of 1% by weight. This increase appears to be caused by the formation of nanostructures in the fluid, initiated by the addition of nanoparticles, is observed by other researchers. This work is aimed at developing a multi-scale analysis to formulate a simulation that facilitates investigation of the physical phenomena behind nanostructure formation. Finally, the future scope for this work is presented.

Download or read book Molten Salt Nanomaterials for Thermal Energy Storage and Concentrated Solar Power Applications written by Donghyun Shin and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The thermal efficiency of concentrated solar power (CSP) system depends on the maximum operating temperature of the system which is determined by the operating temperature of the TES device. Organic materials (such as synthetic oil, fatty acid, or paraffin wax) are typically used for TES. This limits the operating temperature of CSP units to below 400°C. Increasing the operating temperature to 560°C (i.e., the creeping temperature of stainless steel), can enhance the theoretical thermal efficiency from 54% to 63%. However, very few thermal storage materials are compatible for these high temperatures. Molten salts are thermally stable up to 600°C and beyond. Using the molten salts as the TES materials confers several benefits, which include: (1) Higher operating temperature can significantly increase the overall cycle efficiency and resulting costs of power production. (2) Low cost of the molten salt materials can drastically reduce the cost. (3) The molten salts, which are environmentally safe, can also reduce the potential environmental impact. However, these materials suffer from poor thermo-physical properties. Impregnating these materials with nanoparticles can enhance these properties. Solvents doped with nanoparticles are termed as nanofluids. Nanofluids have been reported in the literature for the anomalous enhancement of their thermo-physical properties. In this study, the poor thermal properties of the molten salts were enhanced dramatically on mixing with nanoparticles. For example the specific heat capacity of these molten salt eutectics was found to be enhanced by as much as ~ 26% on mixing with nanoparticles at a mass fraction of ~ 1%. The resultant properties of these nanomaterials were found to be highly sensitive to small variations in the synthesis protocols. Computational models were also developed in this study to explore the fundamental transport mechanisms on the molecular scale for elucidating the anomalous enhancements in the thermo-physical properties that were measured in these experiments. This study is applicable for thermal energy storage systems utilized for other energy conversion technologies - such as geothermal energy, nuclear energy and a combination of energy generation technologies.

Download or read book Solubilities of Inorganic and Organic Compounds written by Atherton Seidell and published by . This book was released on 1928 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molten Salts Chemistry and Technology written by Marcelle Gaune-Escard and published by John Wiley & Sons. This book was released on 2014-05-12 with total page 902 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written to record and report on recent research progresses in the field of molten salts, Molten Salts Chemistry and Technology focuses on molten salts and ionic liquids for sustainable supply and application of materials. Including coverage of molten salt reactors, electrodeposition, aluminium electrolysis, electrochemistry, and electrowinning, the text provides researchers and postgraduate students with applications include energy conversion (solar cells and fuel cells), heat storage, green solvents, metallurgy, nuclear industry, pharmaceutics and biotechnology.

Download or read book Molten Salts and Ionic Liquids written by Marcelle Gaune-Escard and published by John Wiley & Sons. This book was released on 2012-07-06 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: For many years, the related fields of molten salts and ionic liquids have drifted apart, to their mutual detriment. Both molten salts and ionic liquids are liquid salts containing only ions - all that is different is the temperature! Both fields involve the study of Coulombic fluids for academic and industrial purposes; both employ the same principles; both require skilled practitioners; both speak the same language; all then that is truly different is their semantics, and how superficial is that? The editors of this book, recognising that there was so much knowledge, both empirical and theoretical, which can be passed from the molten salt community to the ionic liquid community, and vice versa, organised a landmark meeting in Tunisia, designed to bridge the gap and heal the rift. Leaders from both communities met for a week for a mutual exchange, with a high tutorial content intermixed with cutting edge findings. This volume is a condensate of the principal offerings of that week, and emphasises the success which was achieved. Indeed, four future biannual meetings, under the title of “EUCHEM Conferences on Molten Salts and Ionic Liquids”, have now been planned as a direct result of this meeting of minds. Topics discussed in this volume include structure, dynamics, electrochemistry, interfacial and thermodynamic properties, spectroscopy, synthesis, and theoretical studies. Experimental and theoretical methods for investigating these data are elaborated, as are techniques for data collection and analysis. This book represents the first serious discussion on the transfer of these methods and techniques between the differing temperature regimes, and is a major contribution to the future of both fields.

Download or read book The Art of Molecular Dynamics Simulation written by D. C. Rapaport and published by Cambridge University Press. This book was released on 2004-04 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: First time paperback of successful physics monograph. Copyright © Libri GmbH. All rights reserved.

Download or read book High Energy Density Fuels for Advanced Propulsion written by Ji-Jun Zou and published by John Wiley & Sons. This book was released on 2020-11-09 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprehensively and systematically demonstrates the theory and practice of designing, synthesizing and improving the performance of fuels. The contents range from polycyoalkane fuels, strained fuels, alky-diamondoid fuels, hypergolic and nanofluid fuels derived from fossil and biomass. All the chapters together clearly describe the important aspects of high-energy-density fuels including molecular design, synthesis route, physiochemical properties, and their application in improving the aerocraft performance. Vivid schematics and illustrations throughout the book enhance the accessibility to the relevant theory and technologies. This book provides the readers with fundamentals on high-energy-density fuels and their potential in advanced aerospace propulsion, and also provides the readers with inspiration for new development of advanced aerospace fuels.

Download or read book Nanoparticulate Materials written by Kathy Lu and published by John Wiley & Sons. This book was released on 2012-09-25 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: Serving as the only systematic and comprehensive treatment on the topic of nanoparticle-based materials, this book covers synthesis, characterization, assembly, shaping and sintering of all types of nanoparticles including metals, ceramics, and semiconductors. A single-authored work, it is suitable as a graduate-level text in nanomaterials courses.

Download or read book Piezoelectric Energy Harvesting written by Alper Erturk and published by John Wiley & Sons. This book was released on 2011-04-04 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

Download or read book Molten Salt Chemistry written by Gleb Mamantov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molten salts are of considerable significance to chemical technology. Applications range from the established ones, such as the production of aluminum, magnesium, sodium and fluorine, to those as yet to be fully exploited, such as molten salt batteries and fuel cells, catalysis, and solar energy. Molten salts are investigated for different purposes by many diverse techniques. There is a need to keep investigators working in different areas, such as metal production, power sources, and glass industry, aware of progress in various specialties, as well as to familiarize new research workers with the fundamental aspects of the broad field of molten salt _ chemistry. This volume constitutes the plenary lectures presented at the NATO Advanced Study Institute on Molten Salt Chemistry, Camerino, Italy, August 3-15, 1986. The fundamentals and several selected applications of molten salt chemistry were addressed. The major fundamental topics covered at this ASI were the structure of melts, thermodynamics of molten salt mixtures, theoretical and experimental studies of transport processes, metal-metal salt solutions, solvent properties of melt systems, acid-base effects in molten salt chemistry, electronic absorption, vibrational, and nuclear magnetic resonance spectroscopy of melt systems, electrochemistry and electroanalytical chemistry in molten salts, and organic chemistry in molten salts. The applied aspects of molten salt chemistry included the chemistry of aluminum production, electrodeposition using molten salts, and molten salt batteries and fuel cells.

Download or read book Nanofins written by Navdeep Singh and published by Springer Science & Business Media. This book was released on 2013-11-19 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanofins Science and Technology describes the heat transfer effectiveness of polymer coolants and their fundamental interactions with carbon nanotube coatings that act as nanofins. Heat transfer at micro/nano-scales has attracted significant attention in contemporary literature. This has been primarily driven by industrial requirements where significant decrease in the size of electronic devices/chips with concomitant enhancement in the heat flux have caused challenging needs for cooling of these platforms. With quantum effects kicking in, traditional cooling techniques need to be replaced with more effective technologies. A promising technique is to enhance heat transfer by surface texturing using nanoparticle coatings or engineered nanostructures. These nanostructures are termed as nanofins because they augment heat transfer by a combination of surface area enhancement as well as liquid-solid interactions at the molecular scale.

Download or read book Thermal Energy Storage written by Hafiz Muhammad Ali and published by Springer Nature. This book was released on 2021-04-12 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers various aspects of thermal energy storage. It looks at storage methods for thermal energy and reviews the various materials that store thermal energy and goes on to propose advanced materials that store energy better than conventional materials. The book also presents various thermophysical properties of advanced materials and the role of thermal energy storage in different applications such as buildings, solar energy, seawater desalination and cooling devices. The advanced energy storage materials have massive impact on heat transfer as compared to conventional energy storage materials. A concise discussion regarding current status, leading groups, journals and the countries working on advanced energy storage materials has also been provided. This book is useful to researchers, professionals and policymakers alike.

Download or read book Electrospun Nanofibers written by Mehdi Afshari and published by Woodhead Publishing. This book was released on 2016-09-13 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrospun Nanofibers covers advances in the electrospinning process including characterization, testing and modeling of electrospun nanofibers, and electrospinning for particular fiber types and applications. Electrospun Nanofibers offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science. Electrospinning is the most commercially successful process for the production of nanofibers and rising demand is driving research and development in this field. Rapid progress is being made both in terms of the electrospinning process and in the production of nanofibers with superior chemical and physical properties. Electrospinning is becoming more efficient and more specialized in order to produce particular fiber types such as bicomponent and composite fibers, patterned and 3D nanofibers, carbon nanofibers and nanotubes, and nanofibers derived from chitosan. Provides systematic and comprehensive coverage of the manufacture, properties, and applications of nanofibers Covers recent developments in nanofibers materials including electrospinning of bicomponent, chitosan, carbon, and conductive fibers Brings together expertise from academia and industry to provide comprehensive, up-to-date information on nanofiber research and development Offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science

Download or read book Nanocatalysis written by Vivek Polshettiwar and published by John Wiley & Sons. This book was released on 2013-09-06 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exhibiting both homogeneous and heterogeneous catalytic properties, nanocatalysts allow for rapid and selective chemical transformations, with the benefits of excellent product yield and ease of catalyst separation and recovery. This book reviews the catalytic performance and the synthesis and characterization of nanocatalysts, examining the current state of the art and pointing the way towards new avenues of research. Moreover, the authors discuss new and emerging applications of nanocatalysts and nanocatalysis, from pharmaceuticals to fine chemicals to renewable energy to biotransformations. Nanocatalysis features contributions from leading research groups around the world. These contributions reflect a thorough review of the current literature as well as the authors’ first-hand experience designing and synthesizing nanocatalysts and developing new applications for them. The book’s nineteen chapters offer a broad perspective, covering: Nanocatalysis for carbon-carbon and carbon-heteroatom coupling reactions Nanocatalysis for various organic transformations in fine chemical synthesis Nanocatalysis for oxidation, hydrogenation, and other related reactions Nanomaterial-based photocatalysis and biocatalysis Nanocatalysts to produce non-conventional energy such as hydrogen and biofuels Nanocatalysts and nano-biocatalysts in the chemical industry Readers will also learn about the latest spectroscopic and microscopy tools used in advanced characterization methods that shed new light on nanocatalysts and nanocatalysis. Moreover, the authors offer expert advice to help readers develop strategies to improve catalytic performance. Summarizing and reviewing all the most important advances in nanocatalysis over the last two decades, this book explains the many advantages of nanocatalysts over conventional homogeneous and heterogeneous catalysts, providing the information and guidance needed for designing green, sustainable catalytic processes.