A Molecular Dynamics Study on Heat Transfer Characteristics Over the Interface of Self-Assembled Monolayer and Water Solvent

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Gota Kikugawa ◽  
Taku Ohara ◽  
Tohru Kawaguchi ◽  
Ikuya Kinefuchi ◽  
Yoichiro Matsumoto
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Energy Flux ◽  
Thermal Energy ◽  
Molecular Transport ◽  
Heat Transfer Characteristics ◽  
Self Assembled Monolayer ◽  
Transfer Characteristics ◽  
Water Solvent ◽  
Self Assembled

We performed molecular dynamics (MD) simulations of the interface which is comprised of self-assembled monolayer (SAM) and water solvent to investigate heat transfer characteristics. In particular, local thermal boundary conductance (TBC), which is an inverse of so-called Kapitza resistance, at the SAM–solvent interface was evaluated by using the nonequilibrium MD (NEMD) technique in which the one-dimensional thermal energy flux was imposed across the interface. By using two kinds of SAM terminal with hydrophobic and hydrophilic properties, the local TBCs of these interfaces with water solvent were evaluated, and the result showed a critical difference due to an affinity between SAM and solvent. In order to elucidate the molecular-scale mechanism that makes this difference, microscopic components contributing to thermal energy flux across the interface of hydrophilic SAM and water were evaluated in detail, i.e., the total thermal energy flux is decomposed into the heat transfer modes such as the contribution of molecular transport and that of energy exchange by molecular interactions. These heat transfer modes were also compared with those in the bulk water.

A Molecular Dynamics Study on Heat Transfer Characteristics Over the Interface of Self-Assembled Monolayer and Water Solvent

2011 ◽  
Author(s):  
Gota Kikugawa ◽  
Taku Ohara ◽  
Toru Kawaguchi ◽  
Ikuya Kinefuchi ◽  
Yoichiro Matsumoto
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Energy Flux ◽  
Thermal Energy ◽  
Molecular Transport ◽  
Heat Transfer Characteristics ◽  
Self Assembled Monolayer ◽  
Transfer Characteristics ◽  
Water Solvent ◽  
Self Assembled

We performed molecular dynamics simulations of the interface which is comprised of self-assembled monolayer (SAM) and water solvent to investigate heat transfer characteristics. In particular, local thermal boundary conductance (TBC), which is an inverse of so-called Kapitza resistance, at the SAM–solvent interface was evaluated by using the nonequilibrium MD (NEMD) technique in which the one-dimensional thermal energy flux was imposed across the interface. By using two kinds of SAM terminal with hydrophobic and hydrophilic properties, the local TBCs of these interfaces with water solvent were evaluated, and the result showed a critical difference due to an affinity between SAM and solvent. In order to elucidate the reason for this difference, microscopic components contributing to thermal energy flux across the interface were evaluated in detail, i.e., the total thermal energy flux is decomposed into the contribution of molecular transport and that of energy exchange by molecular interactions.

Natural Convection Heat Transfer Phenomena in Packed Bed Systems

2014 ◽  
Author(s):  
Olugbenga O. Noah ◽  
Johan F. Slabber ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Thermal Energy ◽  
Unit Volume ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Heat Transfer Characteristics ◽  
Coated Particles ◽  
Transfer Characteristics

Natural convection heat transfer in fluid-saturated porous media has in recent years gained considerable attention especially in High Temperature Reactors (HTR). It is lately proposed that Light Water Reactors (LWT) can be made safer by re-designing the fuel in the fuel assembly. In the proposed design, porous medium containing fuel in the form of loose coated particles in a Helium environment is introduced inside the cladding tubes of the fuel elements. These coated particles are treated as a bed from where heat is transferred to the cladding tube and the gas movement is due to natural convection. This proposal will require an understanding of the heat transfer characteristics from heated particles fuel to the gas atmosphere within the cladding tubes. In this present study, the natural convection heat transfer characteristics in packed beds from fluid-to-particle and bed particles to helium gas (thermal energy storage system) was experimentally investigated. Medium condition in this study was homogenous, isotropic, negligible radiant heat transfer and at local thermal non-equilibrium (LTNE). Theoretical formulation of microscopic thermal energy balance in the medium was employed in the analysis of experimental data. This formulation accounts for the convective heat transfer coefficient, the net rate of heat conduction into a unit volume of the solid and the heat production per unit volume of the particle. Dimensionless parameters like the Nusselt, Grashof, Prandtl, Rayleigh and Biot numbers defining heat transfer effect in the medium were equally determined and results validated with the KTA correlation.

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