scholarly journals Temperature and curvature-dependent thermal interface conductance between nanoscale-gold and water from molecular simulation

2022 ◽  
Author(s):  
Blake Wilson ◽  
Steven Nielsen ◽  
Jaona Randrianalisoa ◽  
Zhenpeng Qin
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Interaction Strength ◽  
Thermal Conductance ◽  
Heating Process ◽  
Water Wetting ◽  
Interface Curvature ◽  
Dynamics Simulations ◽  
Curvature Dependence ◽  
Investigate Heat Transfer

Plasmonic gold nanoparticles (AuNPs) can convert laser irradiation into thermal energy and act as nano heaters in avariety of applications. Although the AuNP-water interface is an essential part of the plasmonic heating process,there is a lack of mechanistic understanding of how interface curvature and the heating itself impact interfacial heattransfer. Here, we report atomistic molecular dynamics simulations that investigate heat transfer through nanoscalegold-water interfaces. We confirmed that interfacial heat transfer is an important part of AuNP heat dissipation inAuNPs with diameter less than 100 nm, particularly for small particles with diameter≤10 nm. To account forvariations in the gold-water interaction strength reported in the literature, and to implicitly account for differentsurface functionalizations, we modeled a moderate and a poor AuNP-water wetting scenario. We found that thethermal interface conductance increases linearly with interface curvature regardless of the gold wettability, while itincreases non-linearly, or remains constant, with the applied heat flux under different wetting conditions. Our analysissuggests the curvature dependence of the interface conductance is due to the changes in interfacial water adsorption,while the temperature dependence is caused by heat-induced shifts in the distribution of water vibrational states.Our study advances the current understanding of interface thermal conductance for a broad range of applications.

Thermal Model of the Package Integrated Cyclone COoler (PICCO): Achieving High Thermal Conductance Using Swirled Two-Phase Flow

2020 ◽  
Author(s):  
Rinaldo L. Miorini ◽  
Darin J. Sharar ◽  
Peter deBock
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Heat Conduction Problem ◽  
Thermal Conductance ◽  
Radial Pressure ◽  
High Heat ◽  
Phase System ◽  
Two Phase ◽  
Radial Acceleration ◽  
Us Army

Abstract The demand for high power density, therefore high heat dissipation, power electronics modules is propelled by applications such as hybrid transportation and asynchronous power generation, among others. Besides a low thermal resistance, these applications require high thermal capacitance to manage transient operations. The Package Integrated Cyclone COoler (PICCO) is an additively manufactured, thermal energy storing cooler codesigned by GE Research (GRC) in collaboration with the US Army Research Lab (ARL). The key aspect of PICCO is its capability to swirl a two-phase coolant, i.e. liquid-gas. The centrifugal field creates a radial pressure gradient inducing buoyancy. The strong radial acceleration to which the fluid is subject forces relatively cold flow outward to reach the hot wall, thus boosting the heat transfer, while hot flow and bubbles migrate inward and the two-phase system is nearly isothermal (thermal storage). The proposed study models the swirled flow in terms of liquid film heat conductance and critical heat flux predictions. The resulting heat transfer coefficient can be applied to the walls of the cyclone and used as a boundary condition for the heat conduction problem through the cyclone wall and the module layers.

The Modulation of Interfacial Thermal Resistance in Graphite

2014 ◽  
Author(s):  
Chenhan Liu ◽  
Zhiyong Wei ◽  
Weiyu Chen ◽  
Juekuan Yang ◽  
Yunfei Chen
Keyword(s):  
Thermal Resistance ◽  
Basal Plane ◽  
Heat Dissipation ◽  
Interaction Strength ◽  
Thermal Conductance ◽  
Transmission Function ◽  
Low Frequency ◽  
Blue Shift ◽  
Mean Free Path ◽  
Interfacial Thermal Resistance

It is demonstrated through the nonequilibrium Green’s function method that the interfacial thermal resistance (Ω) of graphite can be modulated by loading pressure in x direction, x and y directions and all three directions respectively in this paper. For graphite without pressure, the interfacial thermal resistance is about 8×10−9 m2K/W. The pressure in the z direction from tensile −1GPa to compressive 10GPa can reduce the Ω by one order of magnitude, which is caused by the increase in the phonon transmission possibility resulting from the increase in the interlayer interaction strength. And the phonon transmission function has the phenomenon of blue shift in the low-frequency range during the process. The pressure in the x-y plane changes from −10GPa to 1.5GPa has slight impact on the phonon transmission and interfacial thermal resistance Ω while there has no pressure or a small pressure in the z direction. So pressure in the basal plane has slight effect on the interfacial thermal conductance and phonon transmission in the graphite. Furthermore, the discrete layer in the graphite separates mutually when the pressure reaches to the critical value 1∼2GPa in the basal plane or to −2∼−1GPa in the z direction. It is worth noted that low-frequency phonons have larger phonon transmission due to longer mean free path and the soft van der Waals interaction between the neighboring layers. Our results suggest that the interfacial thermal resistance of graphite or few-layer graphene can be modulated in a large scope and then can be applied for both heat dissipation and insulation through the pressure engineering.

scholarly journals Identification of the Thermal Conductance of a Hidden Barrier from Outer Thermal Data

2021 ◽  
Vol 8 (1) ◽  
pp. 16
Author(s):  
Gabriele Inglese ◽  
Roberto Olmi ◽  
Agnese Scalbi
Keyword(s):  
Heat Transfer ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Thin Plate ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Thermal Contact Conductance ◽  
Composite Slab ◽  
Thermal Data ◽  
Investigate Heat Transfer

Hidden defects affecting the interface in a composite slab are evaluated from thermal data collected on the upper side of the specimen. First we restrict the problem to the upper component of the object. Then we investigate heat transfer through, the inaccessible interface by means of Thin Plate Approximation. Finally, a Fast Fourier Transform is used to filter data. In this way, we obtain a reliable reconstruction of simulated flaws in thermal contact conductance corresponding to appreciable defects of the interface.

scholarly journals Influence of Vacuum Level on Heat Transfer Characteristics of Maglev Levitation Electromagnet Module

2020 ◽  
Vol 10 (3) ◽  
pp. 1106 ◽  
Author(s):  
Yiqian Mao ◽  
Mingzhi Yang ◽  
Tiantian Wang ◽  
Fan Wu ◽  
Bosen Qian
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Speed ◽  
Heat Dissipation ◽  
Aerodynamic Drag ◽  
Convection Heat Transfer ◽  
Total Heat ◽  
Heating Process ◽  
Convection Heat ◽  
Vacuum Level

The vacuum tube transportation (VTT) system has been a promising direction of future transportation. Within this system, a high-speed maglev travels in a low-vacuum environment to reduce aerodynamic drag. However, the heat dissipation of on-board heating devices will be compromised under low-vacuum conditions, and the device performance may thus be lowered. This study investigates the low-vacuum conjugate heat transfer characteristic of a levitation electromagnet module of a maglev using an experimentally verified numerical method. During the heating process, the surface temperature distribution of the levitation electromagnet, and the temperature and velocity characteristics of the flow field are examined. It is found that, as the vacuum level increases from 1.0 atm to 0.1 atm, the total heat dissipating from the levitation electromagnet module is decreased by 49% at 60 min, the contribution of convection heat flux over the total heat flux is decreased from 49% to 17%, and the convection heat transfer coefficient of the levitation electromagnet is decreased by 89%. This study can provide an efficient numerical model for low-vacuum heat transfer study on a VTT system as well as help the evaluation and optimization of low-vacuum maglev thermal management systems.

Interfacial thermal conductance at metal–nonmetal interface via electron–phonon coupling

2018 ◽  
Vol 32 (31) ◽  
pp. 1830004 ◽  
Author(s):  
Bo Shi ◽  
Xiaofeng Tang ◽  
Tingyu Lu ◽  
Tsuneyoshi Nakayama ◽  
Yunyun Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductance ◽  
Dissimilar Materials ◽  
Experimental System ◽  
Underlying Mechanism ◽  
Metal Interactions ◽  
Interfacial Thermal Conductance ◽  
Interfacial States ◽  
Dynamics Simulations ◽  
Heat Carriers

Interfacial thermal conductance between dissimilar materials plays an important role in solving the overheating problem and thus improving the performance of photonic and electronic devices, especially those at micro- and nano-scale. However, conclusive heat transfer mechanism across interfaces is absent, especially across metal–nonmetal interfaces. Heat transfer across a metal–nonmetal interface is determined by the interplay among different heat carriers. In the metal, both electrons and phonons carry heat, while in the nonmetal, only the phonons are the dominant heat carriers. The interactions among these carriers can be classified into three categories, which correspond to three heat transfer channels, i.e. (i) phonon(metal)–phonon(nonmetal) interactions, which have been widely studied on the basis of the acoustic mismatch theory, diffuse mismatch model, lattice/molecular dynamics simulations; (ii) electron(metal)–phonon(metal) interactions followed by phonon(metal)–phonon(nonmetal) interactions, which were introduced to provide thermal resistance in series with that of the first channel; (iii) electron(metal)–phonon(nonmetal) direct interactions. The third channel has been introduced in order to explain the deviation between experimental results and the existing models incorporating the channel (i) and the channel (ii). Currently, there have been no models to comprehensively capture the underlying mechanism, mainly due to the difficulty in determining/defining the interfacial states at microscopic level and the temperature. Experimentally, it is hard to distinguish the contributions from these channels due to the resolution/sensitivity of the experimental system. Therefore, we here mainly concern with the investigations on the contributions of the channel (iii) from both experimental and theoretical aspects.

Enhancement of Interfacial Thermal Transport by Carbon Nanotube-Graphene Junction

2013 ◽  
Author(s):  
Hua Bao ◽  
Shirui Luo ◽  
Ming Hu
Keyword(s):  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Thermal Transport ◽  
Heat Dissipation ◽  
Thermal Conductance ◽  
Thermal Interface Material ◽  
Interfacial Thermal Resistance ◽  
Material Interfaces ◽  
Material Interface ◽  
Dynamics Simulations

Thermal transport across material interfaces is crucial for many engineering applications. For example, in microelectronics, small interfacial thermal resistance is desired to achieve efficient heat dissipation. Carbon nanotube (CNT) has extremely high thermal conductivity and can potentially serve as an efficient thermal interface material. However, heat dissipation through CNTs is limited by the large thermal resistance at the CNT-material interface. Here we have proposed a CNT-graphene junction structure to enhance the interfacial thermal transport. Non-equilibrium molecular dynamics simulations have been carried out to show that the thermal conductance can be significantly enhanced by adding a single graphene layer in between CNT and silicon. The mechanism of enhanced thermal transport is attributed to the efficient thermal transport between CNT and graphene and the good contact between graphene and silicon surface.

Molecular Dynamics Modeling of Thermal Conductance at Atomically Clean and Disordered Silicon/Aluminum Interfaces

2011 ◽  
Author(s):  
Woon Ih Choi ◽  
Kwiseon Kim ◽  
Sreekant Narumanchi
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Heat Dissipation ◽  
Phonon Scattering ◽  
Thermal Conductance ◽  
Recent Experimental Data ◽  
Dynamics Modeling ◽  
Classical Molecular Dynamics ◽  
Molecular Dynamics Modeling ◽  
Dynamics Simulations

Thermal resistance between layers impedes effective heat dissipation in electronics packaging applications. Thermal conductance for clean and disordered interfaces between silicon (Si) and aluminum (Al) was computed using realistic Si/Al interfaces and classical molecular dynamics with the modified embedded atom method potential. These realistic interfaces, which include atomically clean as well as disordered interfaces, were obtained using density functional theory. At 300 K, the magnitude of interfacial conductance due to phonon-phonon scattering obtained from the classical molecular dynamics simulations was approximately five times higher than the conductance obtained using analytical elastic diffuse mismatch models. Interfacial disorder reduced the thermal conductance due to increased phonon scattering with respect to the atomically clean interface. Also, the interfacial conductance, due to electron-phonon scattering at the interface, was greater than the conductance due to phonon-phonon scattering. This suggests that phonon-phonon scattering is the bottleneck for interfacial transport at the semiconductor/metal interfaces. The molecular dynamics modeling predictions for interfacial thermal conductance for a 5 nm disordered interface between Si/Al are in-line with recent experimental data in the literature.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

Sign in / Sign up

Export Citation Format

Share Document