High-Pressure Densities, Isothermal Compressibilities, and Isobaric Expansivties of Several Nanofluids from Combined Tammann-Tait Equation with Quasi Pack-Cho Approach

An empirical equation based on Tammann-Tait scheme has been previously suggested for nanofluids (Journal of Molecular Liquids, 220, 404 (2016)). This work aimed to develop a new empirical equation for density and derived properties of nanofluids using a combined Tammann-Tait equation of the earlier work with a quasi-Pack-Cho approach as the earlier model mentioned above suffered a mathematical drawback; unrealistic trends for isothermal compressibility and isobaric expansivity with respect to the nanoparticle fraction. Then that drawback has been fixed thorough a revision to earlier work by the help of a quasi-Pack-Cho approach, the nanofluid densities were assumed to be additive, comprising the contributions from the base fluid and from the nanoparticle. The base fluid contributions were obtained from Tammann-Tait equation of earlier work, whereas the nanoparticle contribution was expressed in terms of both fraction and density of nanoparticle as well as some binary parameter. High-pressure densities of 8 nanofluids based on ethylene glycol, poly ethylene glycol, water, poly ethylene glycol + water and ethylene glycol + water was correlated using the new empirical equation mentioned above in 273-363 K range and pressures up to 45 MPa. From 2115 data points examined, the AARD of 0.049% was obtained. The derived thermodynamic coefficients of studied nanofluids were also estimated by the proposed approach. Finally, results of the present empirical model have also been compared with the earlier work and Tammann-Tait type equations of literature, as well.