Density and speed of sound were measured for the ternary 2-methylpropan-1-ol + cyclohexane + toluene system and the binary 2-methylpropan-1-ol + toluene subsystem at temperatures from 293.15 K to 333.15 K and atmospheric pressure. Excess molar volumes and excess isentropic compressibilities were derived from the experimental data to characterize the non-ideal mixing behavior. The predominantly positive excess properties reflect the combined influence of disruption of the self-associated structure of 2-methylpropan-1-ol, interactions between unlike molecules, and changes in molecular packing. The binary excess properties were successfully correlated using the Redlich–Kister polynomial, while the Cibulka equation provided a satisfactory representation of the corresponding ternary data. The Jouyban–Acree model satisfactorily correlated density, speed of sound, isobaric thermal expansivity, and isentropic compressibility over the investigated composition and temperature ranges. PC-SAFT accurately represented the mixture densities, with an overall AAPD of 0.05
This work revisits the ideal line (Zeno curve, Z = 1 ) of the generalized two-constant cubic equation of state (CEoS). The literature describes this curve as a relation between temperature and density. Here, the ideal line pressure is derived as an explicit function of temperature alone, p = f(T) , for any alpha function, with forms for the van der Waals, Redlich–Kwong, Soave–Redlich–Kwong, and Peng–Robinson equations. The same condition gives the density on the ideal line. The van der Waals line is exactly straight in the density–temperature plane. The Redlich–Kwong and Peng–Robinson equations with α = 1 depart from a straight line by 3.6 κ ^* = κ _0 (1 - T_r)^β , fitted to hydrogen and to water below 100 °C, gives average deviations of 6.2
The present study investigates the stability, thermophysical properties, and phase change characteristics of MXene (Ti3C2Tx)-enhanced water-based nanofluid phase change materials (NFPCMs) for cool thermal energy storage (CTES) applications. Stable NFPCM samples were synthesized by dispersing MXene nanosheets in deionized water and characterized through zeta potential, thermal conductivity, specific heat capacity, and latent heat followed by detailed freezing and melting experiments in a spherical encapsulation system. The measured zeta potential values ranged from − 48 mV to − 35 mV, exceeding the conventional stability criterion (≥ 30 mV) and confirming good colloidal stability due to strong electrostatic repulsive interactions between suspended MXene particles. The incorporation of MXene significantly improved the thermal transport properties of the base PCM, resulting in a maximum thermal conductivity enhancement of 29.27
Hydrofluoroethers (HFEs) are considered promising replacements for high global warming potential (GWP) per- and polyfluoroalkyl substances (PFAS) in refrigeration, heat transfer, and electronic cooling applications. However, the scarcity and inconsistency of available thermophysical property data continue to hinder their reliable implementation and modeling. As a follow-up to our previous study on HFE-7300, this work presents a comprehensive experimental investigation of HFE-7500 (C7F15OC2H5), including measurements of critical properties, density, vapor pressure, isobaric heat capacity, and speed of sound over broad temperature and pressure ranges. The experiments were complemented by ab initio calculations of ideal gas thermodynamic properties, resulting in a consistent dataset suitable for thermodynamic modeling. Correlations for vapor pressure, density, and heat capacities were developed and mutually validated for internal thermodynamic consistency. The resulting dataset provides a robust basis for the future development of a multiparameter equation of state for HFE-7500, while the performance of cubic, PC-SAFT, and LKP equations of state was also assessed as an interim modeling approach.
The results of an experimental study of the density and thermal expansion of liquid lead in the temperature range of 602 K to 2026 K are presented. The measurements were performed by the gamma-ray attenuation technique with an uncertainty of 0.12
