Manipulating thermal resistance at the solid–fluid interface through monolayer deposition

At the interface between monolayer coated solid substrate and fluid, the effect of interfacial mismatch on Kapitza length due to the monolayer particles has been extensively analyzed through a series of non-equilibrium molecular dynamics simulation.

Heat Transfer Across Nanoparticle–Liquid Interfaces

A better understanding of submicron-scale heat transfer is rapidly gaining interest due to the complex phenomena involved in nanometer scales. We discuss the role of interfacial resistance, in particular that of curvature effects, and the possibility of achieving high temperatures inside the particles without creating a phase transition in the surrounding fluid. The heat transfer from a heated nanoparticle into surrounding fluid is studied using molecular dynamics (MD) simulations. The results show that the particle size and wetting strength between the nanoparticle–liquid influence the heat transfer characteristics. The interfacial conductance and Kapitza length for a model solid–liquid interface were calculated. Both quantities are found to be strongly dependent on particle size and temperature. Smaller nanoparticles are observed to have a stronger bonding with the interfacial fluid when the temperature of the particle is higher, while larger nanoparticles have better affinity with the liquid at lower temperatures.

Heat Conduction and Interface Thermal Resistance in Liquid Argon Filled Silver and Graphite Nanochannels

Heat conduction between two parallel solid walls separated by liquid argon is investigated using three-dimensional molecular dynamics (MD) simulations. Liquid argon molecules confined in silver and graphite nano-channels are examined separately. Heat flux and temperature distribution within the nano-channels are calculated by maintaining a fixed temperature difference between the two solid surfaces. Temperature profiles are linear sufficiently away from the walls, and heat transfer in liquid argon obeys the Fourier law. Temperature jump due to the interface thermal resistance (i.e., Kapitza length) is characterized as a function of the wall temperature. MD results enabled development of a phenomenological model for the Kapitza length, which is utilized as the coefficient of a Navier-type temperature jump boundary condition using continuum heat conduction equation. Analytical solution of this model results in successful predictions of temperature distribution in liquid-argon confined in silver and graphite nano-channels as thin as 7 nm and 3.57 nm, respectively.

Molecular Dynamics Simulations of Coupling between Flow and Heat Transfer in a Nanochannel

Simulation of microscale thermo-fluidic transport has attracted considerable attention in recent years owing to rapid advances in nanoscience and nanotechnology. The three-dimensional molecular dynamics simulations are performed for coupling between flow and heat transfer in a nanochannel. Effects of interface wettability, shear rate and wall temperature are discussed. It is found that there exist the relatively immobile solid-like layers adjacent to each solid wall with higher number density. Both slip length and Kapitza length at the solid-liquid interface increase linearly with the increasing wall temperature. The Kapitza length decreases monotonously with the increasing shear rates. The slip length is found to be overestimated by 5.10% to 10.27%, while Kapitza length is overestimated by 8.92% to 19.09% for the solid-solid interaction modeled by the Lennard-Jones potential.

Interfacial Thermal Resistance in Nanoscale Heat Transfer

We investigate nanoscale thermal transport across a solid-fluid interface using molecular dynamics simulations. Cooler fluid argon (Ar) is placed between two heated iron (Fe) walls, thereby imposing a temperature gradient within the system. Fluid-fluid and solid-fluid interactions are modeled with Lennard-Jones potential parameters, while Embedded Atom Method (EAM) is used to describe the interactions between solid molecules. The Fe-Ar interaction causes ordering of fluid molecules into quasi-crystalline layers near the walls. This causes temperature discontinuity between these solid-like Ar molecules and the adjacent fluid. The time evolution of the interfacial (Kapitza) thermal resistance (Rk) and Kapitza length (Lk) are observed. The averaged Kapitza resistance (Rk,av) varies with the initial temperature difference between the wall and the fluid (ΔTw) as Rk,av∝ΔTw−0.82.