Thermal Transport in Nanoparticle Packings Under Laser Irradiation

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Heat Transfer ◽  
Laser Irradiation ◽  
Selective Laser Sintering ◽  
Thermal Conductance ◽  
Coupled Model ◽  
Transfer Model ◽  
Copper Nanoparticle ◽  
Glass Substrates ◽  
Interfacial Thermal Conductance ◽  
Nanoparticle System

Abstract Nanoparticle heating due to laser irradiation is of great interest in electronic, aerospace, and biomedical applications. This paper presents a coupled electromagnetic-heat transfer model to predict the temperature distribution of multilayer copper nanoparticle packings on a glass substrate. It is shown that heat transfer within the nanoparticle packing is dominated by the interfacial thermal conductance between particles when the interfacial thermal conductance constant, GIC, is greater than 20 MW/m2K, but that for lower GIC values, thermal conduction through the air around the nanoparticles can also play a role in the overall heat transfer within the nanoparticle system. The coupled model is used to simulate heat transfer in a copper nanoparticle packing used in a typical microscale selective laser sintering (μ-SLS) process with an experimentally measured particle size distribution and layer thickness. The simulations predict that the nanoparticles will reach a temperature of 730 ± 3 K for a laser irradiation of 2.6 kW/cm2 and 1304 ± 23 K for a laser irradiation of 6 kW/cm2. These results are in good agreement with the experimentally observed laser-induced sintering and melting thresholds for copper nanoparticle packing on glass substrates.

Heat Transfer Modeling of Nanoparticle Packings on a Substrate

2018 ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Heat Transfer ◽  
Laser Power ◽  
Thermal Conductance ◽  
Heat Transfer Model ◽  
Experimental Result ◽  
Transfer Model ◽  
Heat Transfer Modeling ◽  
Interfacial Thermal Conductance ◽  
High Laser ◽  
Good Agreement

The temperature evolution of nanoparticle packings on a substrate under high laser power is investigated both experimentally and via numerical simulations. Numerical modeling of temperature distributions in copper nanoparticle packings on a glass substrate is performed and results are compared with experiment under 2.6 kW/cm2 laser power. A coupled electromagnetic-heat transfer model is implemented to understand the nanoparticle temperature distribution. Very good agreement between the coupled electromagnetic-heat transfer model and the experimental results is obtained by matching the interfacial thermal conductance, G, between the nanoparticles using the experimental result in the coupled electromagnetic-heat transfer model.

Experimental Investigation of Interfacial Thermal Conductance for Molten Metal Solidification on a Substrate

1996 ◽  
Vol 118 (1) ◽  
pp. 157-163 ◽  
Author(s):  
G.-X. Wang ◽  
E. F. Matthys
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Conductance ◽  
Measured Temperature ◽  
Solid Contact ◽  
Metal Solidification ◽  
Model Calculations ◽  
Interfacial Thermal Conductance ◽  
Cooling Phase

Experiments have been conducted to quantify the interfacial thermal conductance between molten copper and a cold metallic substrate, and in particular to investigate the heat transfer variation as the initial liquid/solid contact becomes a solid/solid contact after nucleation. A high heat transfer coefficient during the earlier liquid cooling phase and a lower heat transfer coefficient during the subsequent solid splat cooling phase were estimated through matching of model calculations and measured temperature history of the sample. The dynamic variations in the interfacial heat transfer resulting from the solidification process were quantified for splat cooling and were found to be affected by the melt superheat, the substrate material, and the substrate surface finish.

Effect of Interfacial Thermal Conductance Between the Nanoparticles

2018 ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Thermal Management ◽  
Contact Point ◽  
Radiation Heat Transfer ◽  
Thermal Conductance ◽  
Radiation Heat ◽  
Interfacial Thermal Conductance ◽  
Nanostructured Interfaces

Heat transport across nanostructured interfaces, such as between nanoparticles, has been of great interest for advanced thermal management. Interfacial thermal conductance, G, is central to understanding thermal heat transport between nanoparticles that have a contact point between each other as well as the surrounded medium. In this study, we show that G dominates the heat transport compared to the conduction and radiation heat transfer modes between the nanoparticles for values higher than ∼20 (MW/m2K). We also investigate the effect of radius of contact between the nanoparticles on the overall modes of heat transfer.

scholarly journals Thermal contact resistance across a linear heterojunction within a hybrid graphene/hexagonal boron nitride sheet

2016 ◽  
Vol 18 (35) ◽  
pp. 24164-24170 ◽  
Author(s):  
Yang Hong ◽  
Jingchao Zhang ◽  
Xiao Cheng Zeng
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Boron Nitride ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Hexagonal Boron Nitride ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Vital Role ◽  
Interfacial Thermal Conductance

Interfacial thermal conductance plays a vital role in defining the thermal properties of nanostructured materials in which heat transfer is predominantly phonon mediated.

HEAT TRANSFER MODEL FOR PREDICTING SURVIVAL TIME IN COLD WATER IMMERSION

2005 ◽  
Vol 17 (04) ◽  
pp. 159-166 ◽  
Author(s):  
F. TARLOCHAN ◽  
S. RAMESH
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Survival Time ◽  
Cold Water ◽  
Water Immersion ◽  
Thermal Conductance ◽  
Cold Water Immersion ◽  
The Body ◽  
Complex Nature ◽  
Transfer Model

In the present paper a heat transfer (HT) model to estimate survival time of individual stranded in cold water such as at sea is proposed. The HT model was derived based on the assumption that the body specific heat capacity and thermal conductance are not time dependent. The solution to the HT model simulates expected survival time as a function of water temperature, metabolism rate, skin, muscle and fat thickness, insulation thermal conductivity and thickness, height and weight of the subject. Although, these predictions must be considered approximate due to the complex nature of the variables involved, the proposed HT model can be employed to determine supplemental body insulation such as personal protective clothing to meet a predefined survival time in any given water temperature. In particular, the results obtained are useful as a decision aid in search and rescue mission in predicting survival time for shipwreck victims at sea.

scholarly journals Effects of Microscopic Properties on Macroscopic Thermal Conductivity for Convective Heat Transfer in Porous Materials

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1369
Author(s):  
Mayssaa Jbeili ◽  
Junfeng Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Porous Materials ◽  
Thermal Conductance ◽  
Complex Flow ◽  
Material Development ◽  
Interfacial Thermal Conductance ◽  
Apparent Thermal Conductivity

Porous materials are widely used in many heat transfer applications. Modeling porous materials at the microscopic level can accurately incorporate the detailed structure and substance parameters and thus provides valuable information for the complex heat transfer processes in such media. In this study, we use the generalized periodic boundary condition for pore-scale simulations of thermal flows in porous materials. A two-dimensional porous model consisting of circular solid domains is considered, and comprehensive simulations are performed to study the influences on macroscopic thermal conductivity from several microscopic system parameters, including the porosity, Reynolds number, and periodic unit aspect ratio and the thermal conductance at the solid–fluid interface. Our results show that, even at the same porosity and Reynolds number, the aspect ratio of the periodic unit and the interfacial thermal conductance can significantly affect the macroscopic thermal behaviors of porous materials. Qualitative analysis is also provided to relate the apparent thermal conductivity to the complex flow and temperature distributions in the microscopic porous structure. The method, findings and discussions presented in this paper could be useful for fundamental studies, material development, and engineering applications of porous thermal flow systems.

Thermal Transport Mechanisms at Nanoscale Point Contacts

2001 ◽  
Vol 124 (2) ◽  
pp. 329-337 ◽  
Author(s):  
Li Shi ◽  
Arunava Majumdar
Keyword(s):  
Heat Transfer ◽  
Point Contact ◽  
Thermal Conductance ◽  
Contact Forces ◽  
Transfer Model ◽  
Transport Mechanisms ◽  
Point Contacts ◽  
Sample Heat ◽  
Transfer Mechanisms ◽  
Air Conduction

We have experimentally investigated the heat transfer mechanisms at a 90±10 nm diameter point contact between a sample and a probe tip of a scanning thermal microscope (SThM). For large heated regions on the sample, air conduction is the dominant tip-sample heat transfer mechanism. For micro/nano devices with a submicron localized heated region, the air conduction contribution decreases, whereas conduction through the solid-solid contact and a liquid meniscus bridging the tip-sample junction become important, resulting in the sub-100 nm spatial resolution found in the SThM images. Using a one dimensional heat transfer model, we extracted from experimental data a liquid film thermal conductance of 6.7±1.5 nW/K. Solid-solid conduction increased linearly as contact force increased, with a contact conductance of 0.76±0.38W/m2-K-Pa, and saturated for contact forces larger than 38±11 nN. This is most likely due to the elastic-plastic contact between the sample and an asperity at the tip end.

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.

Bio-Heat Transfer Model of Human Eye Subjected to Retinal Laser Irradiation

2010 ◽  
Author(s):  
Arunn Narasimhan ◽  
Kaushal Kumar Jha
Keyword(s):  
Heat Transfer ◽  
Laser Radiation ◽  
Numerical Model ◽  
Laser Irradiation ◽  
Laser Power ◽  
Blood Perfusion ◽  
Transient Temperature ◽  
Transfer Model ◽  
Two Dimensional ◽  
Human Eye

Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two-dimensional numerical model of the human eye geometry has been developed to investigate steady and transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentations and choroidal blood convection — parameterized as a function of choroidal blood perfusion are investigated in detail. The Pennes bio-heat transfer equation is invoked as the governing equation and a finite volume formulation is employed in the numerical method. The numerical model is validated with available experimental and two-dimensional numerical results. For a 500 μm diameter spot size, laser power of 0.2 W, with 100% absorption of laser radiation in the Retinal Pigmented Epithelium (RPE) region, the peak RPE temperature is observed to be 175 °C at steady state, with no blood perfusion in choroid. It reduces to 168.5 °C when the choroidal blood perfusion rate is increased to 23.3 kgm−3s−1. However, under transient simulations, the peak RPE temperature is observed to remain constant at 104 °C after 100 ms of the laser surgery period. A truncated three-dimensional model incorporating multiple laser irradiation spots is also developed to observe the spatial effect of choroidal blood perfusion. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, steady and transient temperature evolution are presented with analysis.

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