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Статті в журналах з теми "Nanoscale interfacial phenomena"
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Luo, Jian, Shen J. Dillon, and Martin P. Harmer. "Interface Stabilized Nanoscale Quasi-Liquid Films." Microscopy Today 17, no. 4 (June 26, 2009): 22–27. http://dx.doi.org/10.1017/s1551929509000121.
Повний текст джерелаАнотація:
A unique class of impurity-based quasi-liquid films has been widely observed at free surfaces, grain boundaries (GBs), and hetero-phase interfaces in ceramic and metallic materials (Figure 1). These nanometer-thick interfacial films can be alternatively understood to be: (a) quasi-liquid layers that adopt an “equilibrium” thickness in response to a balance of attractive and repulsive interfacial forces (in a high-temperature colloidal theory) or (b) multilayer adsorbates with thickness and average composition set by bulk dopant activities [1–2]. In several model binary systems, such quasi-liquid, interfacial films are found to be thermodynamically stable well below the bulk solidus lines, provoking analogies to the simpler interfacial phenomena of premelting in unary systems [3] and prewetting in binary de-mixed liquids [4]. These interfacial films exhibit structures and compositions that are neither observed nor stable as bulk phases, as well as transport, mechanical, and physical properties that are markedly different from bulk phases.
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Agarwal, Neha, Ruma Bhattacharyya, Narendra K. Tripathi, Sanjay Kanojia, Debmalya Roy, Kingsuk Mukhopadhyay, and Namburi Eswara Prasad. "Derivatization and interlaminar debonding of graphite–iron nanoparticle hybrid interfaces using Fenton chemistry." Physical Chemistry Chemical Physics 19, no. 25 (2017): 16329–36. http://dx.doi.org/10.1039/c7cp00357a.
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SHIGA, Tomoyuki, Satoyuki KAWANO, and Kazuhiro NAKAHASHI. "Molecular dynamics simulation on interfacial phenomena in nanoscale liquid drop." Proceedings of the JSME annual meeting 2002.3 (2002): 109–10. http://dx.doi.org/10.1299/jsmemecjo.2002.3.0_109.
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Yuen1, David A., and James R. Rustad. "Workshop on Computational Studies of Interfacial Phenomena: Nanoscale to Mesoscale." Visual Geosciences 3, no. 1 (November 1998): 1–18. http://dx.doi.org/10.1007/s10069-998-1000-0.
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Zhang, Wei, Qihong Feng, Sen Wang, Xianmin Zhang, Jiyuan Zhang, and Xiaopeng Cao. "Molecular Simulation Study and Analytical Model for Oil–Water Two-Phase Fluid Transport in Shale Inorganic Nanopores." Energies 15, no. 7 (March 30, 2022): 2521. http://dx.doi.org/10.3390/en15072521.
Повний текст джерелаАнотація:
Shale reservoirs contain omnipresent nanopores. The fluid transport phenomena on the nanoscale are significantly different from that on the macroscale. The understandings of fluid transport behavior, especially multiphase flow, are still ambiguous on the nanoscale and the traditional hydrodynamic models are insufficient to describe the fluid flow in shale. In this work, we firstly use a molecular dynamics simulation to study the oil–water two-phase flow in shale inorganic quartz nanopores and investigated the unique interfacial phenomena and their influences on fluid transport in a confined nanospace. The results of the molecular simulation revealed that the water-oil-water layered structure was formed in quartz nanopores. There is no-slip boundary condition between water and quartz surface. The density dip and the extremely low apparent viscosity of the oil–water interface region were observed. The liquid–liquid slip effect happened at the oil–water interface. Based on the nano-effects obtained by the molecular simulation, two mathematical models were proposed to describe the nanoscale oil–water two-phase flow, considering both the solid–liquid and liquid–liquid interfacial phenomena, and the performances of two mathematical models were validated. This study shed light on the flow behaviors of oil and water on the nanoscale, and provides the theoretical basis for scale-upgrading, from the nanoscale to the macroscale.
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Landman, Uzi, and W. D. Luedtke. "Interfacial Junctions and Cavitation." MRS Bulletin 18, no. 5 (May 1993): 36–44. http://dx.doi.org/10.1557/s0883769400047102.
Повний текст джерелаАнотація:
Understanding the atomistic mechanisms, energetics, structure, and dynamics underlying the interactions and physical processes that occur when two materials are brought together, separated, or rub against each other (hence the term tribology, from the Greek tribos, meaning to rub) is fundamentally important to many basic and applied problems. Examples include adhesion, capillarity, contact formation, surface deformation, elastic and plastic response characteristics, hardness, micro- and nanoindentation, friction, lubrication, wear, fracture, atomic-scale probing, and modifications and manipulations of materials surfaces. These considerations have for over a century motivated extensive theoretical and experimental research into the above phenomena and their technological consequences.Explorations of materials systems and phenomena in the nanoscale regime often require experimental probes and theoretical and computational methods that allow investigations with refined spatial, as well as temporal, resolution. Consequently, until recently most theoretical approaches to the above issues, with a few exceptions, have been anchored in continuum elasticity and contact mechanics. Experimental observations and measurements of surface forces and the consequent materials response to such interactions have been macroscopic in nature.
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Franceschetti, Donald R. "Finite Element Modeling of Space Charge Phenomena on the Nanoscale." Advances in Science and Technology 46 (October 2006): 120–25. http://dx.doi.org/10.4028/www.scientific.net/ast.46.120.
Повний текст джерелаАнотація:
The NernstPlanckPoisson (NPP) system of equations provides a continuum model for the behavior of interfacial charge in solid ionic conductors. Despite the obvious limitations in using such models to describe systems a few atomic diameters in extent, the success of the PoissonBoltzmann equation in modeling the electrostatic interactions of individual molecules with their ionic atmospheres suggests that continuum solutions have some value as a first approximation in describing charge distributions in nanoparticles and thin layers. Except for static charge distributions onedimensional geometries, solution of the NPP equations requires numerical approximation. Here we examine the applicability of the finite element method to the study of space charge phenomena in selected 1 and 2dimensional geometries, comparison to exactly soluble onedimensional cases to gauge the validity of the results.
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Wang, Ziying, Dhamodaran Santhanagopalan, Wei Zhang, Feng Wang, Huolin L. Xin, Kai He, Juchuan Li, Nancy Dudney, and Ying Shirley Meng. "In Situ STEM-EELS Observation of Nanoscale Interfacial Phenomena in All-Solid-State Batteries." Nano Letters 16, no. 6 (May 9, 2016): 3760–67. http://dx.doi.org/10.1021/acs.nanolett.6b01119.
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Boreyko, J., P. Caveney, S. L. Norred, C. Chin, S. T. Retterer, M. L. Simpson, and C. P. Collier. "Synthetic Biology in Aqueous Compartments at the Micro- and Nanoscale." MRS Advances 2, no. 45 (2017): 2427–33. http://dx.doi.org/10.1557/adv.2017.489.
Повний текст джерелаАнотація:
ABSTRACTAqueous two-phase systems and related emulsion-based structures defined within micro- and nanoscale environments enable a bottom-up synthetic biological approach to mimicking the dynamic compartmentation of biomaterial that naturally occurs within cells. Model systems we have developed to aid in understanding these phenomena include on-demand generation and triggering of reversible phase transitions in ATPS confined in microscale droplets, morpho-logical changes in networks of femtoliter-volume aqueous droplet interface bilayers (DIBs) formulated in microfluidic channels, and temperature-driven phase transitions in interfacial lipid bilayer systems supported on micro and nanostructured substrates. For each of these cases, the dynamics were intimately linked to changes in the chemical potential of water, which becomes increasingly susceptible to confinement and crowding. At these length scales, where interfacial and surface areas predominate over compartment volumes, both evaporation and osmotic forces become enhanced relative to ideal dilute solutions. Consequences of confinement and crowding in cell-sized microcompartments for increasingly complex scenarios will be discussed, from single-molecule mobility measurements with fluorescence correlation spectroscopy to spatio-temporal modulation of resource sharing in cell-free gene expression bursting.
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Шебзухова, М. А., та А. А. Шебзухов. "Фазовое равновесие и поверхностные характеристики в бинарной системе, содержащей наноразмерные частицы". Физика твердого тела 60, № 2 (2018): 390. http://dx.doi.org/10.21883/ftt.2018.02.45398.100.
Повний текст джерелаАнотація:
AbstractA consistent description of phase equilibrium and surface phenomena in binary systems containing monodisperse spherical nanoparticles of arbitrary (including nanoscale) size is presented in the context of the classical method with separating surfaces. Using the obtained relations, we have calculated the composition of coexisting phases and interface layer, and interfacial tension on the boundary between nanoparticles and the matrix at different temperatures in Ti-Mo system. The results of the calculations are consistent with the available experimental data.
Частини книг з теми "Nanoscale interfacial phenomena"
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Bokstein, Boris S., Mikhail I. Mendelev, and David J. Srolovitz. "Interfacial phenomena." In Thermodynamics and Kinetics in Materials Science. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780198528036.003.0008.
Повний текст джерелаАнотація:
An interface is a surface across which the phase changes. Interfaces must be present in all heterogeneous systems, such as those discussed above. Interfacial properties necessarily differ from those of the bulk phases since the atomic bonding/structure of an interface represents a compromise between those of the phases on either side of the interface. For example, an atom at a free surface, which is an interface between a condensed phase and a gas (or a vacuum), generally has fewer neighbors with which to bond than it would have if it were in the bulk, condensed phase. In an equilibrium multi-component system, the chemical potential of each species must be the same in all phases, as well as at the interface. Not surprisingly, the chemical composition of the interface will, in general, differ from that of the bulk. For example, molecules in a gas (or solute in a condensed phase) can adsorb (segregate) onto the surface (interface) of a condensed phase. Interfacial processes play important roles in all areas of materials science and in many (most) areas of modern technology. As the trend toward miniaturization in microelectronics continues and interest in nanoscale structures grows, interfacial phenomena will become even more important. Clearly, the ratio of the number of atoms at surfaces and interfaces to those in the bulk grows as system size decreases (70% of the atoms in a nanometer diameter particle are on a surface!). Therefore, the thermodynamic properties of a system become increasingly dominated by interfacial properties as the dimensions of the system shrink. We can distinguish several types of interfaces: solid–liquid, liquid–gas, solid–gas, solid phase α–solid phase β, and grain boundaries. The meaning of the first four types of interface is self-explanatory. Grain boundaries represent a special class of interfaces; interfaces across which the phase does not change. What does change abruptly across this interface is the spatial orientation of the crystallographic axes. Most crystalline materials are polycrystalline, which means that they are composed of a large number of grains, each with a unique crystallographic orientation with respect to some laboratory frame of reference.
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Carey, Van P. "The Liquid-Vapor Interfacial Region – A Nanoscale Perspective." In Liquid-Vapor Phase-Change Phenomena, 3–37. CRC Press, 2018. http://dx.doi.org/10.1201/9780203748756-1.
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Carey, Van P. "The Liquid-Vapor Interfacial Region: A Nanoscale Perspective." In Liquid-Vapor Phase-Change Phenomena, 3–38. CRC Press, 2020. http://dx.doi.org/10.1201/9780429082221-1.
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Tien, Chang-Lin, and Jian-Gang Weng. "Molecular dynamics simulation of nanoscale interfacial phenomena in fluids." In Advances in Applied Mechanics, 95–146. Elsevier, 2002. http://dx.doi.org/10.1016/s0065-2156(02)80103-x.
Повний текст джерелаТези доповідей конференцій з теми "Nanoscale interfacial phenomena"
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Shou, Wan, and Heng Pan. "Transport and Interfacial Phenomena in Nanoscale Confined Laser Crystallization." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2818.
Повний текст джерелаАнотація:
Laser processing (sintering, melting, crystallization and ablation) of nanoscale materials has been extensively employed for electronics manufacturing including both integrated circuit and emerging printable electronics. Many applications in semiconductor devices require annealing step to fabricate high quality crystalline domains on substrates that may not intrinsically promote the growth of high crystalline films. The recent emergence of FinFETs (Fin-shaped Field Effect Transistor) and 3D Integrated Circuits (3D-IC) has inspired the study of crystallization of amorphous materials in nano/micro confined domains. Using Molecular Dynamics (MD) simulation, we study the characteristics of unseeded crystallization within nano/microscale confining domains. Firstly, it is demonstrated that unseeded crystallization can yield single crystal domains facilitated by the confinement effects. A phenomenological model has been developed and tailored by MD simulations, which was applied to quantitatively evaluate the effects of domain size and processing laser pulse width on single crystal formation. Secondly, to predict crystallization behaviors on confining walls, a thermodynamics integration scheme will be used to calculate interfacial energies of Si-SiO2 interfaces.
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Carey, Van P. "Molecular-Level Modeling of Interfacial Phenomena: Use of Molecular Dynamics Simulations in Tandem With Statistical Thermodynamics Models." In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30157.
Повний текст джерелаАнотація:
Nanoscale aspects of interfacial phenomena can be critically import in convective vaporization and condensation in nanochannels or microchannels. Molecular dynamics (MD) simulations have been extensively used to model and explore the physics of interfacial phenomena at the molecular level. Efforts to improve MD simulations have often focused on development of more physically realistic interaction potentials used to model intermolecular force interactions, or on development of more efficient computing strategies. An important, and often overlooked aspect of MD simulations is the role that theoretical models from statistical thermodynamics can play in MD simulations. This paper argues that use of alternate statistical thermodynamics models, and unconventional strategies for using them, can be effective ways of enhancing MD simulations. The advantages of these types of approaches are explored in the context of three recent MD simulation studies of interfacial region thermophysics that have made use of statistical thermodynamics theory in novel ways. Examples considered include studies of the interfacial region between bulk liquid and vapor phases, thin liquid films on solid surfaces, and stability free thin liquid films. These examples illustrate ways that MD simulations can be combined with other models to enhance computational efficiency or extract more information from the MD simulation results. Successful strategies for implementing these types of scheme are examined, and their general applicability is assessed.
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Nagayama, Gyoko, Masako Kawagoe, and Takaharu Tsuruta. "Molecular Dynamics Simulations of Interfacial Heat and Mass Transfer at Nanostructured Surface." In 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21410.
Повний текст джерелаАнотація:
The nanoscale heat and mass transport phenomena play important roles on the applications of nanotechnologies with great attention to its differences from the continuum mechanics. In this paper, the breakdown of the continuum assumption for nanoscale flows has been verified based on the molecular dynamics simulations and the heat transfer mechanism at the nanostructured solid-liquid interface in the nanochannels is studied from the microscopic point of view. Simple Lennard-Jones (LJ) fluids are simulated for thermal energy transfer in a nanochannel using nonequilibrium molecular dynamics techniques. Multi-layers of platinum atoms are utilized to simulate the solid walls with arranged nanostructures and argon atoms are employed as the LJ fluid. The results show that the interface structure (i.e. the solid-like structure formed by the adsorption layers of liquid molecules) between solid and liquid are affected by the nanostructures. It is found that the hydrodynamic resistance and thermal resistance dependents on the surface wettability and for the nanoscale heat and fluid flows, the interface resistance cannot be neglected but can be reduced by the nanostructures. For the hydrodynamic boundary condition at the solid-liquid interface, the no-slip boundary condition holds good at the super-hydrophilic surface with large hydrodynamic resistance. However, apparent slip is observed at the low hydrodynamic resistance surface when the driving force overcomes the interfacial resistance. For the thermal boundary condition, it is found that the thermal resistance at the interface depends on the interface wettability and the hydrophilic surface has lower thermal resistance than that of the hydrophobic surfaces. The interface thermal resistance decreases at the nanostructed surface and significant heat transfer enhancement has been achieved at the hydrophilic nanostructured surfaces. Although the surface with nanostrutures has larger surface area than the flat surface, the rate of heat flux increase caused by the nanostructures is remarkable.
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Barrat, Jean-Louis, Samy Merabia, Laurent Joly, and Mihail Vladkov. "Simulation of Heat Transfer Around Nanoparticles." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18423.
Повний текст джерелаАнотація:
We present a short review of recent simulation work concerning heat transfer between nanoparticles and a suspending fluid. The role of numerical simulation in understanding such phenomena at a qualitative and quantitative level is emphasized. We discuss in particular the role of interfacial resistance, that of local curvature effects, and the possibility of achieving high temperatures inside the particles without creating a liquid vapor phase transition (boiling) in the surrounding fluid. Our present understanding on nanofluid conductivity from simulation studies is also discussed.
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Kim, Iltai (Isaac), and Kenneth David Kihm. "In-Situ Visualization of Evaporation Induced Self-Assembly Phenomena of Nanofluids Detecting the Interfacial Surface Plasmon Reflectance." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-20804.
Повний текст джерелаАнотація:
Innovative optical techniques based on nano-biophotonics such as surface plasmon resonance (SPR) imaging and R-G-B natural fringe mapping techniques are developed to characterize the transport and optical properties of nanofluids in situ, real-time, and full field manner. Recent results regarding the characterization of nanofluids are summarized and future research directions are presented. 47 nm Al2O3 nanoparticles are dispersed in water with various concentrations. Al2O3 nanofluids droplets are placed on substrates and evaporated in room temperature. In-situ visualization of evaporation-induced self-assembly is conducted to detect concentration, effective refractive index, and different self-assembled pattern including cavity with various nanofluids concentrations and surface hydrophobbicities with SPR and fringe mapping. During the evaporation, time-dependent and near-field nanoparticle concentrations are determined by correlating the SPR reflectance intensities with the effective refractive index (ERI) of the nanofluids. With increasing the concentrations of nanofluids, the existence of hidden complex cavities inside a self-assembled nanocrystalline structure or final dryout pattern is discovered in real-time. R-G-B natural fringe mapping allowed the reconstruction of the 3D cavity formation and crystallization processes quantitatively. The formation of the complex inner structure was found to be attributable to multiple cavity inceptions and their competing growth during the aquatic evaporation. Furthermore, the effect of surface hydrophobicity is examined in the formation of hidden complex cavities, taking place on three different substrates bearing different levels of hydrophobicity; namely, cover glass (CG), gold thin film (Au), and polystyrene dish (PS). These surface plamson resonance imaging and natural fringe mapping techniques are expected to provide a breakthrough in micro-nanoscale thermal fluids phenomena and nano-biochemical sensing when coupled with localized surface Plasmon and metamaterials techniques.
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Sui, P. C., N. Djilali, and Qianpu Wang. "A Pore Scale Model for the Transport Phenomena in the Catalyst Layer of a PEM Fuel Cell." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52152.
Повний текст джерелаАнотація:
In a proton exchange membrane fuel cell (PEMFC), the catalyst layer is a porous medium made of carbon-supported catalysts and solid electrolyte, and has a thickness in the order of 10 μm. Within this layer, complex transport phenomena take place: transport of charged species (H+, electrons and ionic radicals), non-charged species (gaseous H2O, O2, H2, N2 and liquid water) and heat transfer occur in their own pathways. Furthermore, phase change of water and physiochemical/electrochemical reactions also take place on phase boundaries. These transport process take place in an intertwined network of materials having characteristic length scale ranging from nano-meters to micro-meters. The objective of the present study is two-fold, i.e., to develop a rigorous theoretical framework based on which the transport in the micro-structural level can be modelled, and to construct a pore scale model that resolves the geometry of the phases (carbon, ionomer and gas pores) for which direct numerical simulation can be performed. The theoretical framework is developed by employing the volume-averaging techniques for multi-phase porous media. The complete set of the conservation equations for all species in all phases are derived and every interfacial transport is accounted. The problem of model closure on the terms in the transport equations is addressed by the pore-scale model reported in the present study. A 3-D pore-scale model is constructed by a solid model that consists of packing spherical carbon particles and simulated ionomer coating on these carbon aggregates. The index system of the pore-scale model allows easy identification of volumetric pathway, interfaces and triple phase boundaries. The transport of charged and non-charged species is simulated by solving the equations based on first principle in the entire representative element volume (REV) domain. The computational domain contains typically several million cells and a parallelized, iterative solver, GMRES, is employed to solve the coupled transport with complex geometries. Computational results based on the pore-scale model show that the effective transport properties of the species are strongly affected by the micro-structure, e.g. morphology and phase-connectivity. Further simulations and investigation on the coupling effects of the transport are underway. Combination of the proposed theoretical framework and pore-scale model will lay a foundation for the construction of multi-scale modelling of the PEMFC catalyst layer. On the one hand, the pore-scale model helps close the macroscopic volume-averaged equations in the framework. On the other hand, the pore-scale model provides a platform to include microscopic or atomistic simulations.
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Wemhoff, Aaron P., and Van P. Carey. "Exploration of Nanoscale Features of Thin Liquid Films on Solid Surfaces Using Molecular Dynamics Simulations." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59429.
Повний текст джерелаАнотація:
Thin liquid films on solid surfaces are seen in a variety of systems including bubble growth during nucleate boiling and microgroove heat pipe evaporators and condensers. The small thickness of such films leads to difficult experimental observation of phenomena within various regions of the film: the wall-affected region, the bulk liquid, and the liquid-vapor interfacial region. A novel hybrid simulation methodology is used that combines a deterministic molecular dynamics simulation of the liquid regions with a stochastic treatment of the far-field vapor region boundary. In this simulation scheme, the imposed far-field pressure is iterated as the simulation is advanced in time until the mass in the system stabilizes at the specified temperature. This establishes the equilibrium saturation vapor pressure for the specified temperature as dictated by the intermolecular force interaction models for the fluid and molecules near the solid surface. Simulation results are presented for an argon liquid film on a metallic surface. The simulated surface tension values compare favorably with those from ASHRAE tables, although the simulated saturation density and pressure values behave as though the system is at a slightly higher temperature. The method presented here is a viable tool for simulating thin films on solid surfaces for systems operating far from the critical point.
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Yee, Shannon K., Nelson Coates, Jeffrey J. Urban, Arun Majumdar, and Rachel A. Segalman. "A High-Performance Solution-Processable Hybrid Thermoelectric Material." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75002.
Повний текст джерелаАнотація:
Thermoelectrics have the potential to become an alternative power source for distributed electrical generation as they could provide co-generation anywhere thermal gradients exist. More recent material and manufacturing advances have further suggested that thermoelectrics could independently generate primary power [1]. However, due to cost, manufacturability, abundance, and material performance, the full potential of thermoelectrics has yet to be realized. In the last decade, thermoelectric material improvements have largely been realized by diminishing thermal conductivities via nanostructuring without sacrificing performance in electrical transport [2]. An alternative approach is to decouple and optimize the electrical conductivity and thermopower using the unique properties of organic-inorganic interfaces [3]. One method to do this could leverage the electrical properties of a conducting polymer in combination with the thermoelectric proprieties of an inorganic semiconductor in such a way that the interaction between these materials breaks mixture theory. Furthermore, it is expected that the thermal conductivity of this hybrid material would be low due to the inherent vibration mode mismatch between polymers and inorganics. Previously, we have developed a method for producing a solution-processable thermoelectric material suitable for thin film applications using a hybrid polymer-inorganic systems consisting of crystalline tellurium nanowires coated in a thin layer of a conducting polymer (i.e., PEDOT:PSS) [4]. The interfacial properties could be realized in bulk and films demonstrate enhanced transport properties beyond those of either component. More recently, we have been able to significantly improve the thermoelectric properties of these materials by morphological and chemical modifications. Here, we present our methodology and experimental transport properties of this new material where the thermal conductivity, electrical conductivity, and thermopower predictably vary as a function of composition, size, and the structural conformation caused by the solvent. The mechanism for these improvements is currently under investigation, but experimental results suggest that transport is dominated by interfacial phenomena. Furthermore, experiments suggest that both the electrical conductivity and thermopower can be independently increased without appreciably increasing the thermal conductivity. These improvements, in concert with the solution processable nature of this material, make it ideal for new thermoelectric applications.
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Wang, Jingming, Yongmei Zheng, Fu-Qiang Nie, Jin Zhai, and Lei Jiang. "Air Bubble Bursting Effect of Lotus Leaf." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18240.
Повний текст джерелаАнотація:
Superhydrophobic surfaces, especially lotus leaf surface, have been largely explored due to their great importance in fundamental research and abundant potential applications. However, many efforts have been focused on investigating the superhydrophobic surfaces in air instead of in water environment, which are rather crucial to industrial separation progress. A novel air bubble bursting effect on lotus leaf surface was firstly discovered and the underlying mechanism was believed to be related to the micro/nano-hierarchical rough structures. Inspired by air bubble bursting effect on lotus leaf, a superhydrophobic “artificial lotus leaf” with similar micro/nano-hierarchical rough structures was successfully constructed by photolithography and wet etching and also achieved air bubble bursting effect. Smooth and rough silicon surface with the ordered nano-structure or patterned micro-structure were utilized to study the contribution of the micro/nano-hierarchical structures to air bubble bursting, and it was found that air bubble could burst on the superhydrophobic surfaces with micro-structure, but more time was required, while nano-structure could accelerate air bubble bursting. Moreover, the height, width, and spacing of hierarchical structures also affected air bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height of lotus papillae, the width and spacing were significant for air bubble bursting. Eventually, an original model was proposed to further evaluate the reason that the micro/nano-hierarchical rough structures had an excellent air bubble bursting effect, and its validity was theoretically demonstrated. It was believed that these findings should spark further theoretical study of some bubble-related interfacial phenomena and find its wide applications in the industrial separation process without any accessional energy and other additives, such as mineral flotation, food processing, textile dyeing, and fermentation.
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Hoysall, Dhruv C., Khoudor Keniar, and Srinivas Garimella. "Visualization of Two-Phase Flow in Serpentine Heat Exchanger Passages With Microscale Pin Fins." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6576.
Повний текст джерелаАнотація:
Multiphase flow phenomena in single micro- and minichannels have been widely studied. Microchannel heat exchangers offer the potential for high heat transfer coefficients; however, implementation challenges must be addressed to realize this potential. Maldistribution of phases among the microchannels in the array and the changing phase velocities associated phase change present design challenges. Flow maldistribution and oscillatory instabilities can severely affect heat and mass transfer rates as well as pressure drops. In components such as condensers, evaporators, absorbers and desorbers, changing phase velocities can change prevailing flow regimes from favorable to unfavorable. Geometries with serpentine passages containing pin fins can be configured to maintain favorable flow regimes throughout the length of the component for diabatic phase-change heat and mass transfer applications. Due to the possibility of continuous redistribution of the flow across the pin fins along the flow direction, maldistribution can also be reduced. These features enable the potential of high heat transfer coefficients in microscale passages to be fully realized, thereby reducing the required transfer area, and achieving considerable compactness. The characteristics of two-phase flow through a serpentine passage with micro-pin fin arrays with diameters 350 μm and height 406 μm are investigated here. An air-water mixture is used to represent two-phase flow through the serpentine test section, and a variety of flow features are visually investigated using high-speed photography. Improved flow distribution is observed in the serpentine geometry. Distinct flow regimes, different from those observed in microchannels are also established. These observations are used to obtain void fraction and interfacial area along the length of the serpentine passages and compared with the corresponding values for straight microchannels. Models for the two-phase frictional pressure drops across this geometry are also developed.