The calculation of thermal conductivity, viscosity and thermodynamic properties for nanofluids on the basis of statistical nanomechanics

Sensitivity of thermodynamics to the Barker–Henderson (BH) diameter for the Lennard-Jones (LJ) potential is discussed, which covers both its approximation in calculation and improvement in rationality. With regarding to the approximation, pressure and internal energy for the LJ fluid, LJ chains and LJ chain mixtures are investigated. It is found that internal energy is much more sensitive to an approximation to the diameter than pressure for pure fluids, and both pressure and internal energy are very sensitive to the diameter for mixtures. It is also found that the approximating expression given by Cotterman et al. (1986) covers the widest range of temperatures. The rationality of the BH diameter itself at very high temperatures and densities is also analyzed. Through a functional expansion of Helmholtz free energy, we conclude that a density-dependent BH diameter is fundamentally more appropriate. The proposed diameter yields almost the same results as the original BH diameter at normal conditions and remedies its deficiencies at extreme ones. The density-dependent diameter provides a convenient way to study the LJ systems undergoing gas-solid phase transition or freezing.

Role of the Barker–Henderson diameter in thermodynamics

The statistical associating fluid theory (SAFT) equation of state is employed for the correlation and prediction of vapor−liquid equilibrium (VLE) of binary mixtures of alcohols with water, carbon ...

Li Chunxi

Papers

Investigation and improvement of equations of state for Lennard-Jones fluid