Micro and Nano Thermal Transport Research: Characterization, Measurement and Mechanism is a complete and reliable reference on thermal measurement methods and mechanisms of micro and nanoscale materials. The book has a strong focus on applications and simulation, providing clear guidance on how to measure thermal properties in a systematic way. Sections cover the fundamentals of thermal properties before introducing tools to help readers identify and analyze thermal characteristics of these materials. The thermal transport properties are then further explored by means of simulation which reflect the internal mechanisms used to generate such thermal properties. Readers will gain a clear understanding of thermophysical measurement methods and the representative thermal transport characteristics of micro/nanoscale materials with different structures and are guided through a decision-making process to choose the most effective method to master thermal analysis. The book is particularly suitable for those engaged in the design and development of thermal property measurement instruments, as well as researchers of thermal transport at the micro and nanoscale. - Includes a variety of measurement methods and thermal transport characteristics of micro and nanoscale materials under different structures - Guides the reader through the decision-making process to ensure the best thermal analysis method is selected for their setting - Contains experiments and simulations throughout that help apply understanding to practice

Microscale and Nanoscale Heat Transfer: Analysis, Design, and Applications features contributions from prominent researchers in the field of micro- and nanoscale heat transfer and associated technologies and offers a complete understanding of thermal transport in nano-materials and devices. Nanofluids can be used as working fluids in thermal system

Heat transfer at the scales of atoms plays an important role in many applications such as thermoelectric energy conversion and thermal management of microelectronic devices. While nanoengineering offers unique opportunities to manipulate heat to our advantages, it also imposes challenges on the fundamental understanding of nanoscale heat transfer. As the characteristic lengths of the system size become comparable to the mean free paths of heat carriers, macroscopic theories based on heat diffusion are no longer valid due to size effects. Atomistic level simulation can provide powerful insights into the microscopic processes governing heat conduction, and is the focus of this thesis. In this thesis, we first introduce atomistic techniques to investigate phonon transport in bulk crystals. We start with normal mode analysis within the classical molecular dynamics framework to estimate the spectral phonon transport properties. Although it can provide the detailed phonon properties adequately, classical molecular dynamics with empirical potentials do not always yield accurate predictions. Then, we move to first-principles density functional theory (DFT) to compute mode-dependent phonon properties. Such simulations can well reproduce experimental values of phonon dispersion and thermal conductivity with no adjustable parameters, establishing confidence that such an approach can provide reliable information about the microscopic processes. These detailed calculations not only unveil which phonon modes are responsible for heat conduction in bulk crystals, but also expand our fundamental understanding of phonon transport, such as the importance of optical phonons. Next, we study thermal transport across single and multiple interfaces via the atomistic Green's function method, especially the impact of interface roughness on phonon transmission across a single interface and coherent phonon transport in superlattices. Both the DFT and Green's function techniques provide fundamental parameters that then can be used to understand mesoscale transport. This paves the way for multiscale modeling from first-principles. Through these multiscale modeling efforts, we are able to obtain a comprehensive understanding of heat transfer from the atomistic to the macroscale, with important implications for energy applications. Complementary to the theoretical work, we measure the interface thermal conductance using ultrafast time-domain thermoreflectance experiments, examining thermal transport across solid-liquid interfaces modified by self-assembled monolayers. We find that an extra molecular layer can enhance the thermal transport across solid-liquid interfaces. In summary, theoretical, computational and theoretical approaches have been applied to study heat transfer at the atomistic level. The findings from this thesis have improved our fundamental understanding of phonon transport properties with important implications for energy applications and beyond, and build a foundation for multiscale simulation of phonon heat conduction at the mesoscale.

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.

In this Dissertation, the governing mechanisms of thermal energy transfer across solid-liquid interfaces and thin-film evaporation are investigated by means of classical molecular dynamics (MD) simulations. In an effort to steer the heat transfer community from heavily empirical techniques into more physically sound methods, significant attention was given to the formulation physics and chemistry informed interface modelling approaches in MD simulations of heat transfer and evaporation. MD simulations were carried out to characterize and analyze the parameters affecting interfacial heat transport, namely, the solid-liquid affinity, the interfacial vibrational compatibility, and the liquid structuring. Understanding and controlling heat transfer and evaporation is fundamental for various applications, such as photothermal therapy and diagnosis, water desalination, additive manufacturing, energy storage and conversion, and thermal management of high-power electronics. For water desalination, electronics cooling, and nanoparticle-mediated thermotherapy, materials featuring good chemical stability, wide band gap, and biological compatibility are necessary. Therefore, inspired by the current technological interests in solid-liquid interfaces, this Dissertation was dedicated to investigate aqueous interfaces of silicon carbide (SiC) and aluminum oxide (alumina). In addition, graphite-water interfaces were used as a reference framework, since this system has been extensively characterized and studied, and several interfacial modelling parameters are available in the literature. The surface wettability was theoretically and numerically characterized for SiC evaluating the effect of different crystallographic orientations and surface terminations. Anysotropy of wettability was found and analytical models based on Mean-Field theory could adequately describe the wetting behavior for compound materials. In addition, the calculations of the interfacial thermal conductance for SiC showed that the most hydrophilic surfaces were not the most conductive, opposing to the conventional notions that related efficient interfacial thermal transport with hydrophilic surfaces. By including additional parameters, such as the interfacial liquid depletion, a reconciliation of the interfacial thermal conductance was observed, indicating that the surface wettability is only one of the mechanisms involved in the thermal transport phenomena. The potential effect of the liquid structuring on the interfacial thermal transport was verified by the calculation of the thermal conductance at the graphite-water interface. The various interface parameters considered produced a wide spectrum of wetting conditions; nonetheless, no direct relationships between wetting parameters such as the contact angle, the work of adhesion, and the binding energy were observed. Similar to the observed for SiC, the liquid density depletion helped to reconcile the calculations of the interfacial conductance for the graphite-water interface. A more complex interfacial model accounting for surface chemistry and electrostatic interactions was developed to analyze the alumina-water interface. The results indicated that wetting and thin-film evaporation are significantly susceptible to interfacial modeling parameters. Moreover, the improper definition of the atomic interactions led to unphysical droplet spreading when using widely accepted modeling parameters for water-alumina interactions. The characterization of interfacial thermal transport for alumina demonstrated the exitance of an interplay between the solid-liquid affinity, the interfacial vibrational compatibility, and the formation of hydrogen bonds. Thin-film evaporation results showed significant variations in the evaporating film thickness and the evaporation mass fluxes with the different interface models, which demonstrated the crucial role of a robust interfacial modelling approach in capturing evaporation in MD simulations.

Beginning with an overview of nanomachining, this monograph introduces the relevant concepts from solid-state physics, thermodynamics, and lattice structures. It then covers modeling of thermal transport at the nanoscale and details simulations of different processes relevant to nanomachining. The final chapter summarizes the important points and discusses directions for future work to improve the modeling of nanomachining.