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Eingeladener Vortrag
- nein (8)
In dieser Arbeit werden die Grundlagen der Normung, die Entstehung einer Norm und die für die Gasanalytik relevanten Normungsgremien kurz dargestellt. Dazu werden die wichtigsten Normen zur Gasanalytik entlang des analytischen Prozesses gruppiert und aufgeführt. Schließlich wird als Anwendungsbeispiel aus der eigenen Praxis der Prozess von der Herstellung bis zur Zertifizierung eines Kalibriergases beschrieben.
The paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] was subject to multiple high-precision thermophysical property measurements under both ambient and high pressure. Density rho(p0,T) / kg m-3 and speed of sound u(p0,T) / m s-1 data at ambient pressure were recorded at temperatures T = (278.15 to 343.16) K using a DSA 5000 M combined vibrating tube densimeter and speed of sound analyser with a standard uncertainty of delta rho(p0,T) = ±0.001 kg m-3 and delta u(p0,T) = ±0.1 m s-1, respectively. High-pressure volumetric (p,rho,T) data were measured on an Anton Paar DMA HPM vibrating tube densimeter at T = (273.16 to 413.15) K and at pressures up to p = 140 MPa with an estimated experimental relative combined average percentage deviation (APD) of delta rho(p,T) / rho(p,T) = ±(0.01 to 0.08) %.
The specific isobaric heat capacity cp(p0,T) / J kg-1 K-1, a caloric property, was determined at T = (273.15 to 413.15) K with an uncertainty delta cp / cp = ±0.5 % using a Perkin Elmer Pyris 1 DSC differential scanning calorimeter. To gain knowledge of transport properties, the dynamic viscosity eta(p0,T) / mPa s at ambient pressure was recorded at T = (275.03 to 413.18) K by an Anton Paar SVM 3000 Stabinger viscometer and additionally an Anton Paar rheometer MCR 302 device with uncertainties of delta eta / eta = ±0.35 % and delta eta / eta = ±1 %, respectively.
The obtained data were first correlated by empirical polynomial equations of state and further processed by the application of classic thermodynamic potentials to determine isothermal compressibility kappa T(p,T) / MPa-1, isobaric thermal expansivity alpha p(p,T) / K-1, thermal pressure coefficient gamma(p,T) / MPa K-1, internal pressure pint(p,T) / MPa, specific heat capacity at constant pressure cp(p,T) / J kg-1 K-1 and at constant volume cv(p,T) / J kg-1 K-1, the difference of isobaric and isochoric heat capacity (cp–cv)(p,T) / J kg-1 K-1, speed of sound u(p,T) / m s-1 and ultimately isentropic exponent kappa s(p,T).
This work extends knowledge about the thermophysical properties of [BMIM][FeCl4] particularly to high temperatures and pressures.
The decarbonization of the energy sector is driving the interest in hydrogen as an energy-storage medium. A practical alternative to transport and distribute H2 is using the existing infrastructure for natural gas. The GERG-2008 equation of state currently serves as the ISO standard (ISO 20765-2) for the calculation of thermodynamic properties of natural gas, but H2 appears only as a secondary component.
The availability of consolidated data for mixtures with H2 available at the time of its constitution was very limited. The experimental characterization of the thermodynamic behavior of mixtures of H2 with the main components of natural gas is thus of great relevance to validate and improve the GERG-2008 equation of state for its use with H2-enriched natural gas.
Thermodynamics of LNG
(2020)
Densities of eight gravimetrically prepared ternary and quaternary gas mixtures consisting of methane, ethane, propane, and partially nitrogen were investigated along the four isotherms of –250, –230, –210, and –190 °F at pressures of 350, 500, 650, and 1000 psig using a cryogenic single-sinker densimeter. The experimental densities were compared to densities calculated by various models, namely the EOS-LNG fundamental Helmholtz equation of state, the COSTALD correlation, the Lee-Kessler-Plöcker equation of state, and the Peng-Robinson equation of state. The best performance was shown by the EOS-LNG equation of state which is capable of predicting the liquid densities within the specified uncertainty of the model of 0.05 %. The other models, however, showed significant differences that disqualify for calculation within the p,T-region investigated of the gas mixtures.
For the gradual introduction of hydrogen in the energy market, the study of the properties of mixtures of hydrogen with typical components of natural gas (NG) and liquefied petroleum gas (LPG) is of great importance. This work aims to provide accurate experimental (p, rho, T) data for three hydrogen-propane mixtures with nominal compositions (amount of substance, mol/mol) of (0.95 H2 + 0.05 C3H8), (0.90 H2 + 0.10 C3H8), and (0.83 H2 + 0.17 C3H8), at temperatures of 250, 275, 300, 325, 350, and 375 K, and pressures up to 20 MPa. A single-sinker densimeter was used to determine the density of the mixtures. Experimental density data were compared to the densities calculated from two reference equations of state: the GERG-2008 and the AGA8-DC92. Relative deviations from the GERG-2008 EoS are systematically larger than those from the AGA8-DC92. They are within the ±0.5% band for the mixture with 5% of propane, but deviations are higher than 0.5% for the mixtures with 10% and 17% of propane, especially at low temperatures and high pressures. Finally, the sets of new experimental data have been processed by the application of two different statistical equations of state: the virial equation of state, through the second and third virial coefficients, B(T, x) and C(T, x), and the PC-SAFT equation of state.
Continuing our study on (CO2 + O2) mixtures, this work reports new experimental (p, rho, T) data for two oxygen-rich mixtures with mole fractions x(O2) = (0.50 and 0.75) mol·mol−1, in the temperature range T = (250–375) K and pressure range p = (0.5–20) MPa, using a single-sinker densimeter. Experimental density data were compared to two well-established equation-of-state models: EOS-CG and GERG-2008. In the p, T-range investigated, the EOS-CG gave a better reproduction for the equimolar mixture (x(O2) = 0.5), whereas the GERG-2008 performed significantly better for the oxygen-rich mixture (x(O2) = 0.75). The EOS-CG generally overestimates the density, while the GERG-2008 underestimates it. This complete set of new experimental data, together with previous measurements, is used to calculate the virial coefficients B(T, x) and C(T, x), as well as the second interaction virial coefficient B12(T) for the (CO2+ O2) system.
Solubility data of carbon dioxide (CO2) in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][CH3SO3] at T= (273.15 to 413.15) K and pressures up to p= 5.0 MPa are reported. The solubility measurements were carried out using an isochoric method which operates in decrements of ΔT = 20 K within the investigated temperature range and at selected four different pressure steps ranging froma pressure p of around 5.0 MPa down to around 0.4 MPa. The solubility of CO2 in the ionic liquid monotonously decreases with increasing temperatures at a constant pressure. Within the p,T-range investigated, CO2 displayed a solubility in [EMIM] [CH3SO3] from a mole fraction x= 0.0160 mol·mol−1 and a corresponding molality m = 0.0791 mol·kg−1 at T = 413.15 K and p =0.432 MPa up to x = 0.4049 mol·mol−1 and m = 3.2982 mol·kg−1 at T = 293.15 K and p = 4.577 MPa. Henry's law constant was calculated from the solubility data reported here, and literature data were reviewed for comparison. Additionally, thermodynamic state properties that can be derived from Henry's law constant, such as the Gibbs energy of solvation ΔsolG, the enthalpy of solvation ΔsolH, the entropy of solvation ΔsolS, and the heat capacity of solvation ΔsolCp, were calculated.
The use of a biocompatible and thermoresponsive polymer, poly (2-hydroxyethyl methacrylate) (PHEMA) grafted onto the surface of graphene oxide (GO) as an adsorbent for the removal of a cationic dye (methylene blue [MB]) from an aqueous solution is examined in this work. GO–PHEMA forms a hydrogel in water thus overcoming the problem faced by carbon-based adsorbent materials during post-treatment (i.e., separation of adsorbent from the aqueous phase). The GO–PHEMA composite was synthesized using a green approach through dispersion polymerization in supercritical CO2. The successful preparation of this composite was confirmed by a series of characterization techniques. The adsorption behavior of the composite toward MB, such as the effect of the adsorbent dosage, pH, contact time, dye concentration, and recyclability was observed. In addition, the adsorption isotherm, kinetics and thermodynamics were investigated. According to the experimental data, the adsorption parameters were found to fit well into the Freundlich adsorption isotherm with a correlation coefficient of 0.975 and a maximum predicted adsorption capacity of 39.41 mg g−1 at 25 °C. The adsorption kinetics studies showed that the adsorption behavior followed a pseudo-second-order reaction. On the other hand, the thermodynamics studies showed that the adsorption of MB on GO–PHEMA composite followed spontaneous and endothermic adsorption process with an efficient adsorption temperature at 45 °C. The experimental results also showed that the GO–PHEMA composite could remove 99.8 % of the dye in 45 min. Therefore, GO–PHEMA composite is a favorable green adsorbent for environmental applications.