Thermophysical Properties of 1-Butanol at High Pressures

1-Butanol can be considered as a good fuel additive, which can be used at high pressures. Therefore, the knowledge of high-pressure thermophysical properties is crucial for this application. In this paper, new experimental data on the speed of sound in 1-butanol in the temperature range from 293 to 318 K and at pressures up to 101 MPa are reported. The speed of sound at a frequency of 2 MHz was measured at atmospheric and high pressures using two measuring sets operating on the principle of the pulse–echo–overlap method. The measurement uncertainties were estimated to be better than ±0.5 m·s−1 and ± 1 m·s−1 at atmospheric and high pressures, respectively. Additionally, the density was measured under atmospheric pressure in the temperature range from 293 to 318 K using a vibrating tube densimeter Anton Paar DMA 5000. Using the experimental results, the density and isobaric and isochoric heat capacities, isentropic and isothermal compressibilities, isobaric thermal expansion, and internal pressure were calculated at temperatures from 293 to 318 K and at pressures up to 100 MPa.

Comparative study of the thermodynamic behaviour of the binary mixtures dimethyl carbonate + (benzene, n-heptane, cyclohexane, or toluene)

Isobaric molar heat capacities at 288.15, 298.15, and 308.15 K and densities and speeds of sound at 288.15, 293.15, 298.15, and 308.15 K were determined for the dimethyl carbonate + benzene system over the whole composition range and at atmospheric pressure. In addition, speeds of sound at the same temperatures for the dimethyl carbonate + n-heptane system are reported. These experimental data were used to obtain molar volumes, isobaric thermal expansivities, isentropic and isothermal compressibilities, and isochoric molar heat capacities. Excess quantities of the above-mentioned properties were calculated using the Benson and Kiyohara criterion. The thermodynamic behaviour of the dimethyl carbonate + (n-heptane, cyclohexane, benzene, or toluene) systems is comparatively analyzed.Key words: binary mixtures, excess properties, dimethyl carbonate, benzene, hydrocarbon.

A comprehensive thermodynamic investigation of water–ethanolamine mixtures at 10, 25, and 40 °C

The density, isobaric specific heat capacity, and isentropic compressibility of water–ethanolamine (W–EA) mixtures have been measured at three temperatures (10, 25, and 40 °C) over the entire composition range. The results were used to calculate various thermodynamic excess functions of these mixtures, namely: the excess molar volume [Formula: see text] excess molar isentropic and isothermal compressibilities [Formula: see text] excess molar isobaric and isochoric heat capacities [Formula: see text] and excess molar isobaric expansion [Formula: see text] The corresponding partial molar quantities for ethanolamine in the mixtures were also computed. These excess and partial molar quantities were compared with those observed earlier in the water – ethylene glycol (W–EG) (1) and in the water–2-methoxyethanol (W–ME) (2) mixtures. The similarities and differences in the properties of these systems are interpreted on the basis of the specific molecular features of the cosolvents and the concepts of cooperative fluctuations and hydrogen-bonding connectivity in liquid water and dilute aqueous solutions.