Fabrication And Characterization Of Nanostructured Surfaces For Enhanced Heat Transfer

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Fabrication and Characterization of Nanostructured Surfaces for Enhanced Heat Transfer

Author : Changho Choi
Publisher :
ISBN 13 :
Total Pages : 146 pages
Book Rating : 4.:/5 (464 download)

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Book Synopsis Fabrication and Characterization of Nanostructured Surfaces for Enhanced Heat Transfer by : Changho Choi

Download or read book Fabrication and Characterization of Nanostructured Surfaces for Enhanced Heat Transfer written by Changho Choi and published by . This book was released on 2010 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This objective of this study is to investigate the capability of nanostructured surfaces on dissipating heat flux by performing pool boiling and convective flow boiling. The generation of ultra-high heat flux from high performance electric devices has motivated a number of investigations related to advanced heat transfer especially in two-phase boiling performance. It has been reported by a number of researchers that nanostructured surfaces can result in much enhanced boiling performance, compared to the conventional methods by creating desire conditions for heat transfer. In this thesis, various nanostructured surfaces having different morphology were prepared on several engineering relevant substrates and were characterized for their pool boiling performance. Microreactor-assisted-nanomaterial-deposition, MAND [trademark symbol] was used to fabricate a variety of different ZnO nanostructured surfaces by careful adjustment of the processing parameters. ZSM-5 zeolite was synthesized using hydrothermal reaction. ZnO nanostructures in minichannel were also successfully deposited via a flow cell for the application of flow boiling experiment. Scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM) were carried out to characterize the micro- and nanostructures. Contact angle measurement was conducted to evaluate wettability and X-ray Diffraction (XRD) was used to determine the crystalline structures. The most significant enhancement of critical heat flux (CHF) and heat transfer coefficient (HTC) was observed in the flower like ZnO nanostructured surface. We observed pool boiling CHF of 80-82.5 W/cm2 for nanostructured ZnO on Al surfaces versus a CHF of 23.2 W/cm2 on a bare Al surface with a wall superheat reduction of 25-38°C. This new CHF values on nanostructured surfaces corresponds to a boiling heat transfer coefficient as high as ~ 23000 W/m2K. This represents an increase of almost 4X in CHF on nano-textured surfaces, which is the highest enhancement factor reported today.

Fabrication and Robustness Testing of Superhydrophobic Nanostructured Surfaces for Enhanced Jumping Condensation

Author : Jean Hope Sack
Publisher :
ISBN 13 :
Total Pages : 58 pages
Book Rating : 4.:/5 (929 download)

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Book Synopsis Fabrication and Robustness Testing of Superhydrophobic Nanostructured Surfaces for Enhanced Jumping Condensation by : Jean Hope Sack

Download or read book Fabrication and Robustness Testing of Superhydrophobic Nanostructured Surfaces for Enhanced Jumping Condensation written by Jean Hope Sack and published by . This book was released on 2015 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing worldwide and domestic demands for power and clean water will require advanced heat transfer materials. Superhydrophobic micro- and nano-structured surfaces which promote a jumping droplet mode of condensation have been shown to enhance heat transfer over conventional film wise condensation surfaces, but limited robustness testing has been reported validating feasibility of industrial implementation. This thesis seeks to quantify the robustness of a variety of nanostructures, substrates and coatings by analyzing contact angle measurements and SEM imaging over the course of accelerated robustness testing. This testing was enabled through the design and construction of three custom-built setups intended to accelerate the onset of failure mechanisms. These setups consist of a flow setup to observe resistance to shear flows from internal condensation steam flow, a droplet impingement setup to test mechanical durability, and an elevated temperature condensation chamber to characterize thermal stability. Methods for fabricating nanostructures were also developed, and scalable zinc oxide nanowires (ZnO) and copper oxide nanoblades (CuO) were used. CuO nanoblades were etched into copper, and ZnO nanowires were grown on silicon, low carbon steel, titanium, stainless steel, and electroplated nickel. Hydrophobic coatings tested on these surfaces included stearic acid and two polymer coatings: P2i (40nm) and Semblant. Observed failure mechanisms were coating degradation and poor nanostructure adhesion. Nanostrucure adhesion issues were observed as delamination of ZnO nanowires primarily on stainless steel substrates. Adhesion was improved through the addition of an electroplated nickel layer before nanowire growth, but delamination was still observed. This is likely the result a large mismatch in coefficient of thermal expansion between the ZnO nanowires and the substrate. The etched CuO nanostructures with a fluorinated polymer coating (P2i) showed very little change in performance throughout robustness testing. Characterization methods included contact angle measurements to monitor surface uniformity and durability, and scanning electron microscope (SEM) imaging to observe nanostructure degradation and delamination. Preliminary work was also done to functionalize the inside of tubes and design a dedicated test setup to characterize heat transfer measurements for internal jumping condensation. This setup will allow for extended robustness testing over a range of temperatures, pressures, and geometries, and give baseline heat flux values for comparison with dropwise or filmwise internal condensation. While ZnO nanowires still require additional testing and development, CuO nanoblades are good candidates for internal heat transfer measurements and scaled up robustness testing. Assuming this characterization confirms the expected benefits of jumping condensation from increased droplet removal and nucleation density, this technology has the potential to significantly improve power plant efficiency and output worldwide.

Parallel Fabrication and Optoelectronic Characterization of Nanostructured Surfaces

Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)

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Book Synopsis Parallel Fabrication and Optoelectronic Characterization of Nanostructured Surfaces by :

Download or read book Parallel Fabrication and Optoelectronic Characterization of Nanostructured Surfaces written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the more notable accomplishments during the course of this contract we identify the following results: (1) We have used diblock copolymers to transfer nanoscale periodic patterns to substrates. The nanopatterns have been transferred both in the form of etched holes and in arrays of metal dots. This has been performed without the need for silicon nitride layers or multi-layered resists. (2) We have conducted experiments using a closed-loop MM to measure the coefficient of thermal expansion (CTE) of a reference material. We have found that the piezo scanner non-linearity (0.2%) is unacceptably large for metrologic MM Moire interferometry. We have ordered a new closed-loop MM that incorporates a flexure-based scanner with a nonlinearity of 0.05%. The new instrumentation will allow us to overcome the piezo non-linearity difficulties, and (3) We have demonstrated a method for utilizing nanomasks for pattern transfer to an arbitrary substrate via an intermediate transfer layer (ITL). This approach is distinct from the technique of applying the nanomasks directly to the surface to be patterned. The ITL is a layer of a resist-like material into which the bionanomask pattern is transferred before it is then transferred to the substrate.

Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces

Author : Emre Olceroglu
Publisher :
ISBN 13 :
Total Pages : 258 pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces by : Emre Olceroglu

Download or read book Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces written by Emre Olceroglu and published by . This book was released on 2017 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of their adjustable wetting characteristics, micro/nanostructured surfaces are attractive for the enhancement of phase-change heat transfer where liquid-solid-vapor interactions are important. Condensation, evaporation, and boiling processes are traditionally used in a variety of applications including water harvesting, desalination, industrial power generation, HVAC, and thermal management systems. Although they have been studied by numerous researchers, there is currently a lack of understanding of the underlying mechanisms by which structured surfaces improve heat transfer during phase-change. This PhD dissertation focuses on condensation onto engineered surfaces including fabrication aspect, the physics of phase-change, and the operational limitations of engineered surfaces. While superhydrophobic condensation has been shown to produce high heat transfer rates, several critical issues remain in the field. These include surface manufacturability, heat transfer coefficient measurement limitations at low heat fluxes, failure due to surface flooding at high supersaturations, insufficient modeling of droplet growth rates, and the inherent issues associated with maintenance of non-wetted surface structures. Each of these issues is investigated in this thesis, leading to several contributions to the field of condensation on engineered surfaces. A variety of engineered surfaces have been fabricated and characterized, including nanostructured and hierarchically-structured superhydrophobic surfaces. The Tobacco mosaic virus (TMV) is used here as a biological template for the fabrication of nickel nanostructures, which are subsequently functionalized to achieve superhydrophobicity. This technique is simple and sustainable, and requires no applied heat or external power, thus making it easily extendable to a variety of common heat transfer materials and complex geometries. To measure heat transfer rates during superhydrophobic condensation in the presence of non-condensable gases (NCGs), a novel characterization technique has been developed based on image tracking of droplet growth rates. The full-field dynamic characterization of superhydrophobic surfaces during condensation has been achieved using high-speed microscopy coupled with image-processing algorithms. This method is able to resolve heat fluxes as low as 20 W/m2 and heat transfer coefficients of up to 1000 kW/m2, across an array of 1000's of microscale droplets simultaneously. Nanostructured surfaces with mixed wettability have been used to demonstrate delayed flooding during superhydrophobic condensation. These surfaces have been optimized and characterized using optical and electron microscopy, leading to the observation of self-organizing microscale droplets. The self-organization of small droplets effectively delays the onset of surface flooding, allowing the superhydrophobic surfaces to operate at higher supersaturations. Additionally, hierarchical surfaces have been fabricated and characterized showing enhanced droplet growth rates as compared to existing models. This enhancement has been shown to be derived from the presence of small feeder droplets nucleating within the microscale unit cells of the hierarchical surfaces. Based on the experimental observations, a mechanistic model for growth rates has been developed for superhydrophobic hierarchical surfaces. While superhydrophobic surfaces exhibit high heat transfer rates they are inherently unstable due to the necessity to maintain a non-wetted state in a condensing environment. As an alternative condensation surface, a novel design is introduced here using ambiphilic structures to promote the formation of a thin continuous liquid film across the surface which can still provide the benefits of superhydrophobic condensation. Preliminary results show that the ambiphilic structures restrain the film thickness, thus maintaining a low thermal resistance while simultaneously maximizing the liquid-vapor interface available for condensation.

Characterization of Nanostructured Materials for Thermal Conduction and Heat Transfer Control

Author : Alexandros el Sachat
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (112 download)

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Book Synopsis Characterization of Nanostructured Materials for Thermal Conduction and Heat Transfer Control by : Alexandros el Sachat

Download or read book Characterization of Nanostructured Materials for Thermal Conduction and Heat Transfer Control written by Alexandros el Sachat and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Micro and Nanostructured Surfaces for Enhanced Phase Change Heat Transfer

Author : Kuang-Han Chu (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 65 pages
Book Rating : 4.:/5 (847 download)

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Book Synopsis Micro and Nanostructured Surfaces for Enhanced Phase Change Heat Transfer by : Kuang-Han Chu (Ph. D.)

Download or read book Micro and Nanostructured Surfaces for Enhanced Phase Change Heat Transfer written by Kuang-Han Chu (Ph. D.) and published by . This book was released on 2013 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase microchannel heat sinks are of significant interest for thermal management applications, where the latent heat of vaporization offers an efficient method to dissipate large heat fluxes in a compact device. However, a significant challenge for the implementation of microchannel heat sinks is associated with flow instabilities due to insufficient bubble removal, leading to liquid dry-out which severely limits the heat removal efficiency. To address this challenge, we propose to incorporate micro/nanostructures to stabilize and enhance two-phase microchannel flows. Towards this goal, this thesis focuses on fundamental understanding of micro/nanostructures to manipulate liquid and vapor bubble dynamics, and to improve overall microchannel heat transfer performance. We first investigated the role of micro/nanostructure geometry on liquid transport behavior. We designed and fabricated asymmetric nanostructured surfaces where nanopillars are deflected with angles ranging from 7 -52'. Uni-directional liquid spreading was demonstrated where the liquid propagates in a single preferred direction and pins in all others. Through experiments and modeling, we determined that the spreading characteristic is dependent on the degree of nanostructure asymmetry, height-to-spacing ratio of the nanostructures, and intrinsic contact angle. The theory, based on an energy argument, provides excellent agreement with experimental data. This work shows a promising method to manipulate liquid spreading with structured surfaces, which potentially can also be used to manipulate vapor bubble dynamics. We subsequently investigated the effect of micro/nanostructured surface design on vapor bubble dynamics and pool boiling heat transfer. We fabricated micro-, nano-, and hierarchically-structured surfaces with a wide range of well-defined surface roughness factors and measured the heat transfer characteristics. The maximum critical heat flux (CHF) was ~250 W/cm2 with a roughness factor of~-13.3. We also developed a force-balance based model, which shows excellent agreement with the experiments. The results demonstrate the significant effect of surface roughness at capillary length scales on enhancing CHF. This work is an important step towards demonstrating the promising role of surface design for enhanced two-phase heat transfer. Finally, we investigated the heat transfer performance of microstructured surfaces incorporated in microchannel devices with integrated heaters and temperature sensors. We fabricated silicon micropillars with heights of 25 [mu]m, diameters of 5-10 [mu]m and spacings of 5- 10 [mu]m in microchannels of 500 [mu]m x 500 [mu]m. We characterized the performance of the microchannels with a custom closed loop test setup. This thesis provides improved fundamental understanding of the role of micro/nanostructures on liquid spreading and bubble dynamics as well as the practical implementation of such structures in microchannels for enhanced heat transfer. This work serves as an important step towards realizing high flux two-phase microchannel heat sinks for various thermal management applications.

Biotemplated Nanostructured Surfaces for Enhanced Two-phase Heat Transfer

Author : Stephen M. King
Publisher :
ISBN 13 :
Total Pages : 144 pages
Book Rating : 4.:/5 (82 download)

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Book Synopsis Biotemplated Nanostructured Surfaces for Enhanced Two-phase Heat Transfer by : Stephen M. King

Download or read book Biotemplated Nanostructured Surfaces for Enhanced Two-phase Heat Transfer written by Stephen M. King and published by . This book was released on 2012 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Leidenfrost phenomenon is the stable film boiling of a liquid droplet in proximity to a surface whose temperature is much higher than the boiling point of the liquid; caused by rapid vaporization of the droplet before it can come in contact with the surface. This scenario makes conduction through insulating vapor the only means of evaporating the droplet. It is desirable to offset or delay the onset of this occasion of poor heat transfer, the Leidenfrost point, in situations where droplet-to-surface contact is paramount; namely, nuclear reactor safety. Increasing surface hydrophilicity through the implementation of micro, nano, and hierarchical structures has been shown to increase phase-change heat transfer across a surface. In this work, attempts to delay the Leidenfrost phenomenon by tailoring surface wettability with various microstructures conformally coated with novel Tobacco mosaic virus-templated nickel nanostructures are made. Because of a solution based fabrication process, Tobacco mosaic virus nanostructures are potentially more integratable into real-world systems than traditionally fabricated nanostructures. Micropost arrays are patterned in such a way to determine whether the time limiting mechanism in Leidenfrost droplet evaporation is heat transfer or mass transfer dependent. In all, seven patterns (28 samples) with varying thermal conductivities, two-dimensional permeabilities, and heights are: fabricated from SU-8 (photolithography) and silicon (deep reactive-ion etching); tested to determine each surfaces' Leidenfrost point, i.e. the longest droplet evaporation time, through the use of a high-speed camera in concert with a stopwatch; and compared to the performance of flat and nanostructured only surfaces. SU-8 hierarchical posts outperform silicon hierarchical posts, increasing the Leidenfrost point by 175°C (20(mu)m tall) and 250°C (40(mu)m tall) over flat samples, with silicon hierarchies showing only modest improvement,

Heat Pipes

Author : Hussam Jouhara
Publisher : Butterworth-Heinemann
ISBN 13 : 0128234652
Total Pages : 353 pages
Book Rating : 4.1/5 (282 download)

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Book Synopsis Heat Pipes by : Hussam Jouhara

Download or read book Heat Pipes written by Hussam Jouhara and published by Butterworth-Heinemann. This book was released on 2023-10-27 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat Pipes: Theory, Design and Applications, Seventh Edition, takes a highly practical approach to the design and selection of heat pipes, making it an essential guide for practicing engineers and an ideal text for postgraduate students. The expanded author team consolidate and update the theoretical background included in previous editions, and include new sections on recent developments in manufacturing methods, wick design and additional applications. The book serves as an introduction to the theory, design and application of the range of passive, two-phase, heat-transfer devices known as heat pipes, serving as an essential reference for those seeking a sound understanding of the principles of heat pipe technology. It provides an introduction to the basic principles of operation and design data which would permit the reader to design and fabricate a basic heat pipe. It also provides details of the various more complex configurations and designs currently available to assist in selecting such devices.This new edition has been fully updated to reflect the latest research and technologies and includes four brand new chapters on various types of heat pipe, theoretical principles of heat transfer and fluid mechanics, additive manufacturing and heat pipe heat exchangers. Fully revised with brand new chapters on Additive Manufacturing and Heat Exchangers Guides the reader through the design and fabrication of a heat pipe Includes detail on more complex configurations and designs available to assist in the election of devices

Nano-scale Heat Transfer in Nanostructures

Author : Jihong Al-Ghalith
Publisher : Springer
ISBN 13 : 3319738828
Total Pages : 88 pages
Book Rating : 4.3/5 (197 download)

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Book Synopsis Nano-scale Heat Transfer in Nanostructures by : Jihong Al-Ghalith

Download or read book Nano-scale Heat Transfer in Nanostructures written by Jihong Al-Ghalith and published by Springer. This book was released on 2018-03-06 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book introduces modern atomistic techniques for predicting heat transfer in nanostructures, and discusses the applications of these techniques on three modern topics. The study of heat transport in screw-dislocated nanowires with low thermal conductivity in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials, and suggests a new route to lower thermal conductivity that could promote thermoelectricity. The study of high-temperature coating composite materials facilitates the understanding of the role played by composition and structural characterization, which is difficult to approach via experiments. And the understanding of the impact of deformations, such as bending and collapsing on thermal transport along carbon nanotubes, is important as carbon nanotubes, due to their exceptional thermal and mechanical properties, are excellent material candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials.

Parallel Fabrication and Electronic Characterization of Nanostructured and Nanoheterostructured Metal Surfaces

Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (455 download)

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Book Synopsis Parallel Fabrication and Electronic Characterization of Nanostructured and Nanoheterostructured Metal Surfaces by :

Download or read book Parallel Fabrication and Electronic Characterization of Nanostructured and Nanoheterostructured Metal Surfaces written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the more notable accomplishments during the course% of this contract we identify the following results: 0 A precisely ordered and precisely located array of 5 nm diameter nanoclusters has been fabricated by first etching into the substrate an array of holes with diameters comparable to the size of nanoclusters sought and then depositing adatoms on the substrate. Our methods enable rapid fabrication of arrays for fundamental studies and provide a route to manufacturability of nanostructure arrays for technological purposes. We reported the ability to control the morphology of nanometer thick Ti oxide films which were created via a parallel nanofabrication process using a two-dimensional protein crystal as a template. Atomic force microscopy was used to examine the evolution of these structures from a periodic array of nanometer-scale dots (nanodots) to a screen containing a periodic array of nanometer-scale holes (nanoscreen) as the film thickness was increased. We reported the creation of large arrays of nanometer-scale dots (nanodot arrays) with the oxides of several additional metals near Ti in the periodic table. A computer simulation of nanoscale hole formation based on curvature dependent sputtering and surface self-diffusion was formulated. The model simulates the experimental data from our nanopatterning process quite well.

Fabrication and a Study of the Wetting Properties of Nanostructured Surfaces

Author :
Publisher :
ISBN 13 :
Total Pages : 169 pages
Book Rating : 4.:/5 (259 download)

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Book Synopsis Fabrication and a Study of the Wetting Properties of Nanostructured Surfaces by :

Download or read book Fabrication and a Study of the Wetting Properties of Nanostructured Surfaces written by and published by . This book was released on 2007 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid behavior at the microscale exhibits large surface to volume ratios increasing the significance of interfacial phenomena. We have studied two microfluidic phenomena that utilize interplay between microstructure and chemical composition. The first one causes liquid droplets to roll off from surfaces with a very high contact angle. This phenomenon is called superhydrophobic behavior, can be controlled by several tuning parameters. The second one changes the wettability of liquids on a dielectric coated surface with electric potential. The experimental studies were done by first fabricating an ordered array of glass nanocones. Fiber drawing and differential glass etching processes were used to produce cone like structures with lattice constant of 40 [Mu]m down to 1.6 [Mu]m. The superhydrophobic behavior was first studied and modeled in a series of nanocone wafers of increasing aspect ratio from .3 to 15. The characterization was done by the measurement of the contact and rolling angles. The Wenzel to Cassie transition of wetting states was observed. The contact angles were calculated by using the 'axisymmetric drop shape analysis' approach. Next, the study of the electrowetting behavior of two broad categories of structured surfaces was done. One was a low aspect ratio surface exhibiting Wenzel wetting and the other was a high aspect ratio surface exhibiting Cassie wetting. The device for experimental study was prepared by coating additional layers, which included conductive gold and dielectric Parylene-C coatings. Studies were done using silicone oil and air as the ambient medium. Images of drops were taken at different voltages and the contact angles were calculated geometrically. Electrowetting on nanocone arrays was modeled using an energybased approach and the obtained theoretical curves were compared to the experimental ones. Oil helped in achieving a large contact angle change. A qualitative analysis of the electrowetting properties of the surfaces was done based on the voltage-contact angle curves.

Thermal Characterization of Nanostructures and Advanced Engineered Materials

Author : Vivek Kumar Goyal
Publisher :
ISBN 13 :
Total Pages : 170 pages
Book Rating : 4.:/5 (798 download)

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Book Synopsis Thermal Characterization of Nanostructures and Advanced Engineered Materials by : Vivek Kumar Goyal

Download or read book Thermal Characterization of Nanostructures and Advanced Engineered Materials written by Vivek Kumar Goyal and published by . This book was released on 2011 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuous downscaling of Si complementary metal-oxide semiconductor (CMOS) technology and progress in high-power electronics demand more efficient heat removal techniques to handle the increasing power density and rising temperature of hot spots. For this reason, it is important to investigate thermal properties of materials at nanometer scale and identify materials with the extremely large or extremely low thermal conductivity for applications as heat spreaders or heat insulators in the next generation of integrated circuits. The thin films used in microelectronic and photonic devices need to have high thermal conductivity in order to transfer the dissipated power to heat sinks more effectively. On the other hand, thermoelectric devices call for materials or structures with low thermal conductivity because the performance of thermoelectric devices is determined by the figure of merit Z=S 2 [sigma]/ K, where S is the Seebeck coefficient, K and [sigma] are the thermal and electrical conductivity, respectively. Nanostructured superlattices can have drastically reduced thermal conductivity as compared to their bulk counterparts making them promising candidates for high-efficiency thermoelectric materials. Other applications calling for thin films with low thermal conductivity value are high-temperature coatings for engines. Thus, materials with both high thermal conductivity and low thermal conductivity are technologically important. The increasing temperature of the hot spots in state-of-the-art chips stimulates the search for innovative methods for heat removal. One promising approach is to incorporate materials, which have high thermal conductivity into the chip design. Two suitable candidates for such applications are diamond and graphene. Another approach is to integrate the high-efficiency thermoelectric elements for on-spot cooling. In addition, there is strong motivation for improved thermal interface materials (TIMs) for heat transfer from the heat-generating chip to heat-sinking units. This dissertation presents results of the experimental investigation and theoretical interpretation of thermal transport in the advanced engineered materials, which include thin films for thermal management of nanoscale devices, nanostructured superlattices as promising candidates for high-efficiency thermoelectric materials, and improved TIMs with graphene and metal particles as fillers providing enhanced thermal conductivity. The advanced engineered materials studied include chemical vapor deposition (CVD) grown ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films on Si substrates, directly integrated nanocrystalline diamond (NCD) films on GaN, free-standing polycrystalline graphene (PCG) films, graphene oxide (GOx) films, and "pseudo-superlattices" of the mechanically exfoliated Bi 2 Te 3 topological insulator films, and thermal interface materials (TIMs) with graphene fillers.

Fabrication and Characterization in the Micro-Nano Range

Author : Fernando A. Lasagni
Publisher : Springer
ISBN 13 : 9783642267543
Total Pages : 222 pages
Book Rating : 4.2/5 (675 download)

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Book Synopsis Fabrication and Characterization in the Micro-Nano Range by : Fernando A. Lasagni

Download or read book Fabrication and Characterization in the Micro-Nano Range written by Fernando A. Lasagni and published by Springer. This book was released on 2013-04-21 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book shows an update in the field of micro/nano fabrications techniques of two and three dimensional structures as well as ultimate three dimensional characterization methods from the atom range to the micro scale. Several examples are presented showing their direct application in different technological fields such as microfluidics, photonics, biotechnology and aerospace engineering, between others. The effects of the microstructure and topography on the macroscopic properties of the studied materials are discussed, together with a detailed review of 3D imaging techniques.

Advances in Heat Transfer

Author : Ephraim M. Sparrow
Publisher : Academic Press
ISBN 13 : 0124079326
Total Pages : 360 pages
Book Rating : 4.1/5 (24 download)

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Book Synopsis Advances in Heat Transfer by : Ephraim M. Sparrow

Download or read book Advances in Heat Transfer written by Ephraim M. Sparrow and published by Academic Press. This book was released on 2013-11-19 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Transfer fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in journals or texts. The articles, which serve as a broad review for experts in the field, will also be of great interest to non-specialists who need to keep up-to-date with the results of the latest research. This serial is essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, graduate schools or industry. This serial is essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, graduate schools or industry

Template Directed Fabrication and Characterization of 1D Nanostructures for Nanoelectronics

Author : Muhammad Ibrahim Khan
Publisher :
ISBN 13 :
Total Pages : 408 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Template Directed Fabrication and Characterization of 1D Nanostructures for Nanoelectronics by : Muhammad Ibrahim Khan

Download or read book Template Directed Fabrication and Characterization of 1D Nanostructures for Nanoelectronics written by Muhammad Ibrahim Khan and published by . This book was released on 2008 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Proceedings of the International Conference on Integration and Commercialization of Micro and Nanosystems, 2007: Micro and nano systems ; Micro and nano devices ; Micro and nano mechanics ; Energy and micro and nano scale heat transfer

Download Proceedings of the International Conference on Integration and Commercialization of Micro and Nanosystems, 2007: Micro and nano systems ; Micro and nano devices ; Micro and nano mechanics ; Energy and micro and nano scale heat transfer PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 1016 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Proceedings of the International Conference on Integration and Commercialization of Micro and Nanosystems, 2007: Micro and nano systems ; Micro and nano devices ; Micro and nano mechanics ; Energy and micro and nano scale heat transfer by :

Download or read book Proceedings of the International Conference on Integration and Commercialization of Micro and Nanosystems, 2007: Micro and nano systems ; Micro and nano devices ; Micro and nano mechanics ; Energy and micro and nano scale heat transfer written by and published by . This book was released on 2007 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Multiscale Modeling of Nanostructure-Enhanced Two-Phase Heat Transfer

Author : Han Hu
Publisher :
ISBN 13 :
Total Pages : 304 pages
Book Rating : 4.:/5 (958 download)

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Book Synopsis Multiscale Modeling of Nanostructure-Enhanced Two-Phase Heat Transfer by : Han Hu

Download or read book Multiscale Modeling of Nanostructure-Enhanced Two-Phase Heat Transfer written by Han Hu and published by . This book was released on 2016 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase heat transfer has been widely used in the thermal management of electronics and energy systems. The critical heat flux and heat transfer coefficient of two-phase heat transfer can be significantly enhanced using nanostructures. The objective of current research is to develop the fundamental understandings regarding how nanostructures affect the two-phase heat transfer in the aspects of disjoining pressure, meniscus shape, Kapitza resistance, and evaporative heat transfer coefficient so as to guide nanostructural design for improving heat transfer performance. A multiscale modeling approach is introduced to examine the effects of nanostructures and electrostatic interactions on the equilibrium meniscus shape and disjoining pressure of a thin liquid film on nanostructured surfaces. A general continuum-level model is developed based on the minimization of free energy, the Derjaguin approximation, and the disjoining pressure theory for a flat surface. Molecular dynamics (MD) simulations are performed for water thin films of varying thickness on gold and alumina surfaces with both triangular and square nanostructures of varying depth. Good agreement is obtained between the continuum-level modeling and MD simulations. The results show that the wave amplitude of the meniscus increases with decreasing thin film thickness and increasing nanostructure depth. The electrostatic interactions are shown to enhance the disjoining pressure and make the meniscus more conformal to the nanostructured surfaces. Furthermore, both van der Waals and electrostatic contributions to the disjoining pressure increase with the nanostructure depth and decrease with the film thickness. The effect of nanostructures on Kapitza resistance of water boiling on a gold surface is examined via molecular dynamics simulations. The results show that Kapitza resistance is reduced with increasing nanostructure depth due to the enhanced solid-liquid interactions, and with decreasing nanostructure spacing due to the reduced mismatch in the vibrational properties between the solid and liquid. A closed-form model for the heat transfer coefficient of thin film evaporation on nanostructured surfaces is derived by integrating the evaporation kinetics, disjoining pressure, and Kapitza resistance. Molecular dynamics simulations are performed for water thin films of varying thickness on square gold nanostructures of varying depth. Good agreement is obtained between the continuum-level models and MD simulations. The results also show that there exists a critical film thickness at which the heat transfer coefficient reaches its maximum value. For a film with thicknesses below the critical film thickness, the evaporation resistance dominates the heat transfer, and the heat transfer coefficient increases with film thickness and decreases with nanostructure depth. For a film with thicknesses above the critical film thickness, the conduction resistance dominates the heat transfer, and heat transfer coefficient decreases with film thickness and increases with nanostructure depth. In addition, the critical film thickness increases with the nanostructure depth. The maximum heat transfer coefficient also increases with the nanostructure depth due to the reduction in Kapitza resistance.