TY - JOUR A1 - Lozano-Martín, D. A1 - Pazoki, F. A1 - Kipphardt, Heinrich A1 - Khanipour, P. A1 - Tuma, Dirk A1 - Horillo, A. A1 - Chamorro, C. R. T1 - Thermodynamic (p, ρ, T) characterization of a reference high-calorific natural gas mixture when hydrogen is added up to 20 % (mol/mol) N2 - The injection of hydrogen into the natural-gas grid is an alternative during the process of a gradual decarbonization of the heat and power supply. When dealing with hydrogen-enriched natural gas mixtures, the performance of the reference equations of state habitually used for natural gas should be validated by using high-precision experimental thermophysical data from multicomponent reference mixtures prepared with the lowest possible uncertainty in composition. In this work, we present experimental density data for an 11-compound high-calorific (hydrogen-free) natural gas mixture and for two derived hydrogen-enriched natural gas mixtures prepared by adding (10 and 20) mol-% of hydrogen to the original standard natural gas mixture. The three mixtures were prepared gravimetrically according to ISO 6142–1 for maximum precision in their composition and thus qualify for reference materials. A single-sinker densimeter was used to determine the density of the mixtures from (250–350) K and up to 20 MPa. The experimental density results of this work have been compared to the densities calculated by three different reference equations of state for natural gas related mixtures: the AGA8-DC92 EoS, the GERG-2008 EoS, and an improved version of the GERG-2008 EoS. While relative deviations of the experimental density data for the hydrogen-free natural gas mixture are always within the claimed uncertainty of the three considered equations of state, larger deviations can be observed for the hydrogen-enriched natural gas mixtures from any of the three equations of state, especially for the lowest temperature and the highest pressures. KW - Hydrogen-enriched natural gas KW - Single-sinker densimeter KW - High-pressure density KW - Equations of state PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604742 DO - https://doi.org/10.1016/j.ijhydene.2024.05.028 SN - 0360-3199 VL - 70 SP - 118 EP - 135 PB - Elsevier BV CY - Amsterdam AN - OPUS4-60474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, D. A1 - Tuma, Dirk A1 - Kipphardt, Heinrich A1 - Khanipour, Peyman A1 - Chamorro, C. R. T1 - Thermodynamic characterization of the (H2 + C3H8) system significant for the hydrogen economy: Experimental (p, rho, T) determination and equation-of-state modelling N2 - 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. KW - Hydrogen-containing gas mixture KW - Density data KW - Equation of state KW - Virial coefficients PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570056 DO - https://doi.org/10.1016/j.ijhydene.2022.11.170 SN - 0360-3199 VL - 48 IS - 23 SP - 8645 EP - 8667 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-57005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Segovia, J. J. A1 - Tuma, Dirk A1 - Lozano-Martín, D. A1 - Moreau, A. A1 - Martín, M. C. A1 - Vega-Maza, D. T1 - Speed of sound data and acoustic virial coefficients of two binary (N2 + H2) mixtures at temperatures between (260 and 350) K and at pressures between (0.5 and 20) MPa N2 - This work aims to address the technical concerns related to the thermodynamic characterization of gas mixtures blended with hydrogen for the implementation of hydrogen as a new energy vector. For this purpose, new experimental speed of sound measurements have been done in gaseous and supercritical phases of two binary mixtures of nitrogen and hydrogen using the most accurate technique available, i.e., the spherical acoustic resonator, yielding an experimental expanded (k = 2) uncertainty of only 220 parts in 106 (0.022%). The measurements cover the pressure range between (0.5 and 20) MPa, the temperature range between (260 and 350) K, and the composition range with a nominal mole percentage of hydrogen of (5 and 10) mol%, respectively. From the speed of sound data sets, thermophysical properties that are relevant for the characterization of the mixture, namely the second βa and third γa acoustic virial coefficients, are derived. These results are thoroughly compared and discussed with the established reference mixture models valid for mixtures of nitrogen and hydrogen, such as the AGA8-DC92 EoS, the GERG-2008 EoS, and the recently developed adaptation of the GERG-2008 EoS, here denoted GERG-H2_improved EoS. Special attention has been given to the effect of hydrogen concentration on those properties, showing that only the GERG-H2_improved EoS is consistent with the data sets within the experimental uncertainty in most measuring conditions. KW - Speed of sound KW - Acoustic resonance KW - Binary gas mixture PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551482 DO - https://doi.org/10.1016/j.jct.2022.106791 SN - 0021-9614 VL - 171 SP - 1 EP - 13 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-55148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Moreau, A. A1 - Polishuk, I. A1 - Segovia, J. J. A1 - Vega-Maza, D. A1 - Martín, M. C. T1 - Measurements and predictions of densities and viscosities in CO2 + hydrocarbon mixtures at high pressures and temperatures: CO2 + n-pentane and CO2 + n-hexane blends N2 - This work reports new experimental data on densities and viscosities of (CO2 + n-pentane) and (CO2 + n-hexane) mixtures at high pressures and temperatures. The densities were measured by a vibrating-tube densimeter with an expanded uncertainty (k = 2) smaller than 1.8 kg/m3 at six isotherms (from 273.15 K to 373.15 K), twelve pressures starting at 5 MPa up to 100 MPa, and at six CO2 molar compositions (from 0 to 0.6). The viscosities were measured by a vibrating-wire viscometer with the corresponding relative expanded uncertainty (k = 2) smaller than 0.016 at five isotherms (from 273.15 K to 373.15 K), twelve pressures (from 5 MPa up to 100 MPa), and at two CO2 molar compositions (0.1 and 0.3). The densities were fitted by the semiempirical Tammann-Tait equation for density data and the Vogel-Fulcher-Tammann (VFT) equation for viscosity data, respectively. The Groupe Européen de Recherches Gazières (GERG-2008) equation of state was also applied for modelling the densities. Over-all robustness and reliability of the Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT) and its critical point-based modification (CP-PC-SAFT) were examined. Accuracies of the Modified Yarranton-Satyro (MYS) coupled with CP-PC-SAFT and the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10) in predicting the viscosities were evaluated. KW - CO2 + n-alkanes KW - thermophysical properties KW - Perturbed-Chain Statistical Association Fluid Theory PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555728 DO - https://doi.org/10.1016/j.molliq.2022.119518 SN - 0167-7322 VL - 360 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam AN - OPUS4-55572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Kumbhar, V. S. A1 - Lee, Y. R. A1 - Ra, C. S. A1 - Min, B.-K. A1 - Shim, J.-J. T1 - Modified chemical synthesis of MnS nanoclusters on nickel foam for high performance all-solid-state asymmetric supercapacitors N2 - Novel MnS nanoclusters were synthesized on nickel foam (NF) using a successive ionic layer adsorption and reaction (SILAR) method. MnS nanoclusters with different sizes were obtained by varying the number of deposition cycles. The crystal structure, chemical composition, and surface microstructure of the electrodes were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field Emission scanning electron microscopy, and high-resolution transmission electron microscopy. The electrochemical behavior of the MnS nanoclusters was examined by cyclic voltammetry, galvanostatic charge–discharge, cycling test, and electrochemical impedance spectroscopy. The MnS nanoclusters prepared with 90 SILAR cycles showed the best supercapacitance in a 6 M KOH aqueous electrolyte with a specific capacitance of 828 F/g at a scan rate of 5 mV/s and cycling stability of 85.2 % after 5000 charge–discharge cycles. Moreover, an asymmetric supercapacitor (ASC) was assembled with the as-prepared MnS electrode on NF as the positive electrode, hydrothermally prepared reduced graphene oxide (rGO) on NF as the negative electrode, and PVA–KOH gel as the electrolyte. The MnS@NF//rGO@NF ASC showed excellent electrochemical performance with maximum energy and power densities of 34.1 Wh/kg and 12.8 kW/kg, respectively. The ASC also showed a capacitive retention of 86.5 % after 2000 charge–discharge cycles, highlighting its practical application for energy storage. KW - Nanocluster KW - Electrochemical behavior KW - Asymmetric supercapacitor KW - Graphene oxide PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-403147 DO - https://doi.org/10.1039/c7ra00772h SN - 2046-2069 VL - 7 IS - 27 SP - 16348 EP - 16359 PB - The Royal Society of Chemistry CY - London AN - OPUS4-40314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -