Modified Tammann Tait Equation Research Articles

Thermodynamic and Transport Properties of Biomass-Derived Furfural, Furfuryl Alcohol and Their Mixtures

The limited reserves and well-known disadvantages of using fossil energy sources have increased the need for appropriate renewable substitutes in the production of various chemicals and materials. Biomass has been shown to be worthy of attention since it can be converted to biofuels and value-added chemicals relatively easily. The design of biomass valorisation process requires knowledge on the thermodynamic behaviour of the biomass-derived compounds, such as furfural and furfuryl alcohol. The thermodynamic and transport properties of the binary system furfural + furfuryl alcohol were studied at various temperatures and pressures. Density, speed of sound and refractive index were measured in the temperature range T = (288.15–345.15) K and viscosity was measured at temperatures up to 373.15 K, all at atmospheric pressure. Further, the density of pure components was obtained in the temperature range (293.15–413.15) K for furfural and (293.15–373.15) K for furfuryl alcohol at pressures up to 60.0 MPa. The obtained density values were correlated using the modified Tammann–Tait equation with an average absolute deviation lower than 0.009% for furfural and furfuryl alcohol. The optimised parameters were used for the calculation of the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the isobaric and isochoric specific heat capacities. The reported data are a valuable source of information for the further application of the investigated compounds.

PρT measurements and modelling of (n-decane + m-xylene) mixtures from 293.15 K to 363.15 K at pressures up to 60 MPa

In this work, the experimental measurements for liquid densities of n-decane and m-xylene binary mixtures were performed over the entire composition range with a high-pressure vibrating-tube densimeter. The range of temperatures for the present measurements was from 293.15 K to 363.15 K and the pressures were up to 60 MPa. The combined expanded uncertainty of the density measurements is estimated to be 0.001ρ with 0.95 confidence. Experimental density values were correlated by the modified Tammann-Tait equation. The simplified Perturbed Associating Fluid Theory (sPC-SAFT) and Cubic Plus Associated (CPA) equations of state (EoS) were applied to predict the densities of n-decane and m-xylene and their mixtures. Reasonably results were observed between the experimental data and calculated results for the two equations, and the deviation is less than 0.48% and 0.89% with sPC-SAFT and CPA EoS, respectively. In addition, excess molar volumes were determined from the experimental density data as well as from sPC-SAFT and CPA models. The effects of pressure and temperature on the excess molar volume were also discussed.

High pressure densities and derived properties of biodiesel fuel produced by heterogeneous transesterification from biowaste

High pressure density of biodiesel is a crucial parameter necessary for the Diesel engine design and performance improvement as well as proper combustion optimization. Biodiesel production utilizing biowaste as raw material reduces the capital costs and environmental problems related to biowaste disposal. In this investigation, biodiesel was synthesized in a heterogeneous transesterification reaction utilizing used cooking oil and methanol as reactants and eggshell raw material as a calcium-oxide catalyst source. Calcination was carried out at temperature 1073.15 K for 4 hours and transesterification was conducted at 338.15 K. Densities of produced biodiesel were measured at pressures up to 60 MPa and over the temperature range 288.15-413.15 K and fitted employing the modified Tammann-Tait equation. Viscosities of biodiesel are also measured at atmospheric pressure over the temperature range 288.15-338.15 K. From measured density data, important mechanical properties, such as the isothermal compressibility and the isobaric thermal expansivity, were calculated. High transesterification reaction yield was obtained (almost 99 wt.%) while densities and viscosities of analyzed biodiesel sample were in accordance with recommended standard values.

Densities and Derived Volumetric Properties of Ionic Liquids with [Nf2] and [NTf2] Anions at High Pressures

The densities of four ionic liquids: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([E3Mim][Nf2]), n-propyl-n-methylpyrrolidinium bis(fluorosulfonyl)imide ([PMpyr][Nf2]), 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide ([BMpyr][Nf2]), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonil)imide ([BMpyr][NTf2]) were measured at temperatures (293.15 to 413.15) K and pressures (0.1 to 60) MPa. The experimental density data were modeled using the modified Tammann–Tait equation and the average absolute percentage deviations between measured and calculated values for all studied ionic liquids were less than 0.004%. The optimized parameters were used to calculate the isothermal compressibility, the isobaric thermal expansivity, the internal pressure, and the difference between specific heat capacities at constant pressure and at constant volume. The cation and anion influences on the properties of the ionic liquids were examined. The longer alkyl chains on cations are related to lower densit...

Liquid densities for n-decane + p-xylene mixtures from 293.15 K to 363.15 K at pressures up to 60 MPa

The experimental measurements for liquid densities of n-decane and p-xylene binary mixtures were performed over the entire composition with a high-pressure vibrating-tube densimeter. The temperature ranges for the present measurement were from 293.15 K to 363.15 K and the pressures were reached to 60 MPa. The experimental uncertainty is estimated to be 0.001 with 0.95 confidence level. Experimental density values were fitted by the modified Tammann–Tait equation. The PC-SAFT equation of state and Cibulka's equation was used to predict the densities of n-decane and p-xylene and its mixtures. In addition, derived volumetric properties, such as the excess molar volumes, the isothermal compressibility, and isobaric thermal expansivity, were calculated from the experimental density data. The effects of pressure and temperature on the derived properties were also discussed.

Experimental Investigation and Modeling of Thermophysical Properties of Pure Methyl and Ethyl Esters at High Pressures

Densities, speeds of sound, and refractive indices of methyl laurate, ethyl laurate, ethyl myristate, and ethyl oleate in the temperature range 288.15–343.15 K and viscosities from 288.15 to 373.15 K were measured at atmospheric pressure. The measured properties were in good agreement with several available literature data, finding an overall absolute average percentage deviation (AAD) of 0.04%, 0.07%, 3%, and 0.1% for density, speed of sound, viscosity, and refractive index, respectively. The densities of mentioned esters were also measured along 15 isotherms from 293.15 to 413.15 K and at pressures up to 60 MPa using an Anton Paar DMA HP densimeter. Based on the literature data selected for comparison, in the studied ranges of temperature and pressure, the AADs of high-pressure densities were 0.08% for methyl laurate, 0.06% for ethyl laurate, and 0.05% for ethyl myristate. The obtained density values were correlated through the modified Tammann–Tait equation with an AAD lower than 0.009% for all the stu...

High pressure densities and derived thermodynamic properties for the (n-heptane + n-octane + ethanol) ternary system

The density of the ternary system (n-heptane+n-octane+ethanol) at temperatures from (293.15 to 373.15)K and at pressures from (0.1 to 40)MPa was experimentally determined at twelve compositions and the results are presented here. Measurements were performed using high pressure U-tube cell DMA HP coupled with DMA 5000 vibrating density meter. To fit the experimental density values the modified Tammann-Tait equation was applied. Excess molar volumes were also calculated at all pressures and temperatures in order to explain to what extent the investigated mixtures deviate from ideal behaviour. Moreover, the influence of pressure and temperature on density was studied by calculating isothermal compressibility and isobaric thermal expansion coefficient. It was found that non-ideal behaviour of the ternary mixture is strongly influenced by pressure and temperature conditions.

High-pressure liquid densities and derived thermodynamic properties for methyl laurate and ethyl laurate

In this work, experimental density data are reported for methyl laurate and ethyl laurate from 283.15 to 363.15K at pressures up to 60MPa using a vibrating-tube densimeter. Estimated relative uncertainty of density measurement is 0.001 with a confidence level of 0.95. The experimental data were fitted with a modified Tammann-Tait equation. Average relative deviations between experimental data and calculated results from the equation were 0.016% for methyl laurate and 0.014% for ethyl laurate. In addition, the derived thermodynamic properties, such as isobaric thermal expansivity and isothermal compressibility, were calculated from the modified Tammann-Tait equation.

Thermodynamic properties of biodiesel and petro-diesel blends at high pressures and temperatures. Experimental and modeling

One of the solutions to greenhouse gases emission is the use of biodiesels, since their mixtures with petro-diesel can be used as fuel in existing diesel engines without additional corrections in engines’ design. In order to estimate engine performance and increase its efficiency, it is necessary to know the basic properties of fuels under different operating conditions, and among the most important ones are density and viscosity. Therefore, the densities of pure petro-diesel, as well as densities of its blends with sunflower oil methyl and ethyl esters, in the ratio of 10vol% and 20vol% of the biodiesel, at temperatures 293.15–413.15K and at pressures of 0.1–60MPa, are presented here. Measurements were taken at an Anton Paar DMA HP densimeter. For the device calibration the classical calibration method with one reference fluid was applied. Also, for the same samples, the viscosities at 288.15–373.15K and the refractive indices at 288.15–343.15K at atmospheric pressure were measured. Measured densities decrease linearly as temperature rises along isobars and increase with pressure rise at a constant temperature for all examined samples. Refractive index, also, decreases linearly with temperature rise, while viscosity decreases exponentially with increase in temperature. Densities and refractive indices are higher for blends with sunflower oil methyl esters than with its ethyl esters, opposite to viscosity. Densities of blends increase linearly with rise in biodiesel share, while the increase of viscosity is exponential. Density data were fitted to the modified Tammann-Tait equation and the obtained results were used for calculation of derived thermodynamic properties such as the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the difference between specific heat capacity at constant pressure and the specific heat capacity at constant volume. The absolute average percentage deviations of the measured densities from those calculated using the modified Tammann-Tait equation were about 0.01%, for all studied samples, assessing positively the correlation procedure. The dependence of the measured and calculated properties of the blends on biodiesel amount was also examined.

Densities and derived thermodynamic properties for the (n-heptane + n-octane), (n-heptane + ethanol) and (n-octane + ethanol) systems at high pressures

This work reports densities for the pure n-heptane, n-octane and ethanol at temperatures from (288.15 to 413.15)K and at pressures up to 60MPa. The same properties were determined for the binary mixtures n-heptane + n-octane, n-heptane + ethanol and n-octane + ethanol over the temperature range (293.15–373.15)K and at pressures ranging from (0.1 to 40)MPa. Highly precise densimeter DMA HP was used for density measurements. Experimental values of densities were fitted by the modified Tammann–Tait equation. Additionally, derived volumetric properties, e.g. excess molar volumes, isothermal compressibilities and isobaric thermal expansion coefficients were calculated. The effect of pressure and temperature on the measured and derived properties was discussed.

Densities of the Binary Systems n-Hexane + n-Decane and n-Hexane + n-Hexadecane Up to 60 MPa and 463 K

The densities of the binary systems n-hexane + n-decane and n-hexane + n-hexadecane have been measured up to 60 MPa using a vibrating tube densimeter. The measurements covered the whole composition range; for the first system they were performed from (278.15 to 463.15) K, while for the latter they were performed from (298.15 to 463.15) K because n-hexadecane is a solid at 278.15 K. The densities were correlated for every composition as a function of temperature and pressure using a modified Tammann–Tait equation with standard deviations lower than 8·10–4 g·cm–3. Isothermal compressibility values were calculated from the experimental density data. Moreover, the excess volumes were found to be negative for all of the studied mixtures, with absolute values less than or equal to 3.25 cm3·mol–1 for the n-hexane + n-decane system and 7.65 cm3·mol–1 for the n-hexane + n-hexadecane system. Various equations of state were used to model the measured density data.

Biodiesel density and derived thermodynamic properties at high pressures and moderate temperatures

Knowledge of the basic thermodynamic properties of biodiesel under different conditions is necessary because of its wide use as a substitute for fossil fuels. The viscosities and refractive indices of the methyl and ethyl esters of the fatty acids from sunflower oil were measured at atmospheric pressure and at temperatures 288.15–373.15K and 288.15–343.15K, respectively. The same properties were measured also for the methyl esters of the fatty acids from lard at atmospheric pressure and at temperatures 298.15–373.15K and 298.15–343.15K, respectively. The densities of the mentioned biodiesel samples were measured at temperatures up to 413.15K and at pressures 0.1–60MPa. The experimental density values were correlated using the modified Tammann–Tait equation. Based on the obtained results, thermodynamic behavior, such as the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the difference between the specific heat capacity at constant pressure and at constant volume, were calculated. The absolute average deviations between measured densities and those calculated using the modified Tammann–Tait equation of about 0.006% for all of the three examined samples confirm the accuracy of the modeling and reliability of the calculated derived properties.