Implications of the Interface Modelling Approach on the Heat Transfer Across Solid-Liquid Interfaces and Thin-Film Evaporation

Download or read book Implications of the Interface Modelling Approach on the Heat Transfer Across Solid-Liquid Interfaces and Thin-Film Evaporation written by Carlos Gonzalez-Valle and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.