Correlation between thermal conductivity of nanofluids and their structural, electronic and thermodynamic properties: DFT study

Abstract

In this study, we address the critical challenge of enhancing thermal conductivity in nanofluids, a key factor for improving heat transfer efficiency in various industrial applications. Using density functional theory (DFT), we systematically investigate the relationship between thermal conductivity and the structural, electronic, and thermodynamic properties of Silver (Ag), Copper (Cu), Gold (Au), and Aluminum (Al) nanofluids. We analyze quantum chemical parameters, including molecular orbital energies, energy gap (ΔE_GAP), ionization potential (I), electron affinity (A), hardness (η), and local softness (σ), alongside thermodynamic properties such as enthalpy (ΔH), Gibbs free energy (ΔG), entropy (ΔS), and heat capacity (Cv). Our results demonstrate that Ag nanofluids exhibit superior thermal conductivity (429 W/m·K), supported by their high values of E_HOMO (−3.5325 eV), E_LUMO (−2.0781 eV), and σ (1.3751), as well as low values of ΔE_GAP (1.4544 eV), I (3.5325 eV), A (2.0781 eV), and η (0.7272 eV). These findings reveal a strong correlation between thermal conductivity and quantum chemical parameters. Additionally, thermodynamic calculations for Ag and Al nanofluids highlight that the high thermal conductivity of Ag is driven by its elevated ΔH, ΔS, and Cv values. This work provides novel insights into the design of high-performance nanofluids by establishing a quantitative link between thermal conductivity and fundamental material properties, advancing beyond previous studies in the literature.