A thermodynamic framework for the thermal conductivity of dense fluids

TL;DR

This paper introduces a thermodynamic framework that accurately predicts the thermal conductivity of dense simple fluids by relating it to their thermodynamic properties, extending beyond dilute-gas conditions.

Contribution

The authors derive a universal formula for thermal conductivity of dense fluids based on thermodynamic properties, applicable across a wide range of fluid densities and validated against simulations and experiments.

Findings

Quantitative agreement with hard sphere simulation data.

Captures supercritical Lennard-Jones fluid behavior.

Matches experimental data for argon.

Abstract

A thermodynamic framework that predicts the thermal conductivity $\lambda$ of simple fluids beyond the dilute-gas limit is introduced. By generalizing the transition-rate approach of particles on a lattice to conserved quantities in continuous space, an expression for the ratio $\lambda/\lambda_{\rm id}$ is derived, where $\lambda_{\rm id}$ is the dilute-gas value; the ratio depends solely on equilibrium thermodynamic properties and is therefore directly computable from any equation of state. The resulting formula quantitatively reproduces simulation data for hard spheres throughout almost the entire fluid range, and captures the behavior of Lennard-Jones fluids in the supercritical region where thermodynamic fluctuations remain moderate. Comparison with experimental data for argon, reported by other authors, also shows good agreement. These results provide evidence that transport coefficients of dense fluids can be expressed as their dilute-gas values multiplied by a universal function of equilibrium thermodynamic properties.