Thermophysical properties of diphenylmethane and dicyclohexylmethane as a reference liquid organic hydrogen carrier system from experiments and molecular simulations

Kerscher, Manuel; Klein, Tobias; Schulz, P.; Veroutis, Emmanouil; Dürr, Stefan; Preuster, Patrick; Koller, Thomas M.; Rausch, Michael H.; Economou, Ioannis G.; Wasserscheid, Peter; Fröba, Andreas P.

doi:10.1016/j.ijhydene.2020.07.261

Cited by 42 publications

(48 citation statements)

References 70 publications

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“…For the absolute determination of the liquid viscosity and the interfacial tension in macroscopic thermodynamic equilibrium, the contactless, optical technique surface light scattering (SLS) is used in this work as well as previous publications. − Using this method, the temporal behavior of light scattered from microscopic surface fluctuations at a phase boundary is analyzed and related to the fluid properties according to the complete theoretical description of the dynamics of surface waves. , This SLS technique has been successfully applied to a variety of reference fluids and multiphase systems ,− with typical expanded uncertainties ( k = 2) of both properties of 2%.…”

Section: Introductionmentioning

confidence: 99%

Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

et al. 2021

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This work contributes to the characterization of three binary liquid hydrocarbon-based mixtures via the determination of density, viscosity, and interfacial tension over the entire concentration range up to temperatures of 573.15 K. The oscillating-tube method, surface light scattering (SLS), and equilibrium molecular dynamics (EMD) simulations are applied to analyze the influences of chain length, branching, and hydroxylation on the aforementioned thermophysical properties. For probing these effects, the three binary systems of n-hexadecane (1) with n-octacosane (2), 1-hexadecanol (2), or 2,2,4,4,6,8,8-heptamethylnonane (2), each with mole fraction of x 1 = 0.25, 0.5, or 0.75, are investigated in macroscopic thermodynamic equilibrium at or close to saturation conditions at temperatures between 298.15 and 573.15 K. Based on the experimental results for the liquid densities, liquid viscosities, and interfacial tensions with average expanded uncertainties (k = 2) of 0.10, 2.0, and 1.8%, respectively, our previously published modification to the optimized potentials for the liquid simulations (OPLS) force field for long hydrocarbons (L-OPLS) is evaluated for its transferability to liquid mixtures in EMD simulations. Considering all simulation results, the average absolute relative deviations for the density, viscosity, and interfacial tension are 0.74, 27, and 14%, respectively. Experimental results are also applied for the evaluation of simple prediction models based on pure-component properties. Especially at high temperatures, such simple mixing rules perform well. At lower temperatures, however, nonidealities like surface enrichment or the formation of molecule clusters in the mixture are more likely to dominate fluid behavior, leading to a failure of the simple mixing rules. To explain this observation, partial-density profiles and radial distribution functions from simulations, giving access to the fluid structure on a microscopic level, are evaluated.

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Section: Introductionmentioning

confidence: 99%

Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

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“…The used optical and electronic arrangement of the SLS setup analyzing the scattered light in transmission direction perpendicular to the phase boundary is identical to the one employed in Ref. [16] and is described in detail in Refs. [1,2].…”

Section: Methodsmentioning

confidence: 99%

“…On the basis of the findings from the present work, further investigations are currently ongoing, with the aim of establishing relationships between the characteristics of molecules in form of their orientation at the interface and the evaluation of SLS experiments. In this regard, apparent limitations of the classical hydrodynamic theory observed for benzene-based LOHCs [16,17] seem to have only an impact on the surface tension, but not on the viscosity as bulk property.…”

Section: Surface Tensionmentioning

confidence: 99%

“…In the context of thermophysical property research, SLS has been applied for the measurement of viscosity and surface tension of various types of working fluids in process and energy engineering [2]. Here, refrigerants [7][8][9], hydrocarbons [10][11][12], ionic liquids [13][14][15], and liquid organic hydrogen carriers (LOHCs) [16,17] can be mentioned as examples. Furthermore, SLS investigations on the reference fluids toluene [1,6] and diisodecyl phthalate [18] contributed to the development of standards of low viscosity [19] and moderately high viscosity [20].…”

Section: Introductionmentioning

confidence: 99%

“…Investigations on the viscosity and surface tension of benzene by SLS, which are lacking until now, are stimulated by various reasons. From our currently ongoing studies on LOHC systems based on diphenylmethane (DPM) [16,17], it was found that the surface tensions obtained from SLS are between about (6 to 1)% smaller than data from the conventional pendant drop method for temperatures from (303 to 523) K [16]. Such discrepancies, which are comparable or even larger for mixtures of DPM with its hydrogenated counterpart and for the partially hydrogenated intermediate cyclohexylphenylmethane [17], indicate possible molecular orientation effects at the fluid interface causing a self-induced surface dipole moment or charge polarization [33,34].…”

Section: Introductionmentioning

confidence: 99%

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Viscosity and Surface Tension of Benzene at Saturation Conditions from Surface Light Scattering

2021

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In the present study, the liquid viscosity and surface tension of benzene was determined at saturation conditions from surface light scattering (SLS) experiments between (283 and 393) K. Based on the application of the hydrodynamic theory for surface fluctuations at the vapor–liquid phase boundary which was successfully validated by the measurements, a simultaneous determination of liquid viscosity and surface tension with average relative expanded uncertainties (k = 2) of (1.0 and 0.8)% was achieved. Agreement between the measurement data and reference values available in the literature was found for the viscosity and in general also for the surface tension, where benzene constitutes a recommended reference material of relatively moderate surface tension values. All these findings demonstrate for a repeated time that SLS is a suitable method for the investigation of fluids including reference fluids such as benzene, which enables a sound representation of its surface tension, presumably as a result of a rather random molecular orientation at the surface. Overall, the experimental results from this work could contribute to an improved data situation for benzene, in particular with respect to providing viscosities and surface tensions at true saturation conditions.

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Viscosity and Interfacial Tension of Binary Mixtures Consisting of Linear, Branched, Cyclic, or Oxygenated Hydrocarbons with Dissolved Gases Using Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

et al. 2022

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In the present study, the influence of the molecular characteristics of the solvent and solute on the dynamic viscosity and interfacial tension of binary mixtures consisting of a liquid with a dissolved gas is investigated using surface light scattering (SLS) and equilibrium molecular dynamics (EMD) simulations. In detail, binary mixtures consisting of linear, branched, cyclic, or oxygenated hydrocarbons and the solutes hydrogen, helium, methane, water, carbon monoxide, or carbon dioxide are studied in the temperature range between (298 and 573) K and for solute mole fractions up to 0.2. With SLS, the liquid dynamic viscosity and interfacial tension of the binary mixtures could be accessed in macroscopic thermodynamic equilibrium with average expanded uncertainties (coverage factor k = 2) of (2.4 and 2.3)%, respectively. While EMD simulations were able to predict the influence of the dissolved gases on the interfacial tension of the binary mixtures, the simulations fail to represent the influence of the dissolved gas on the viscosity. Due to the systematic variation of the solvent and solute molecules, the influence of the molecular characteristics, e.g., in the form of size, shape, or polarity, on the thermophysical properties of the mixtures is discussed. Dissolving carbon dioxide, e.g., leads to a reduction of both properties by up to 60% compared to the properties of the pure solvent. Dissolved helium, on the other hand, has only a small influence on the properties of the pure solvent. The influence of dissolved water was found to be negligible in mixtures with an alkane but strongly increases both properties when dissolved in an alcohol, which may be explained by the formation of hydrogen bonds.

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Thermophysical properties of diphenylmethane and dicyclohexylmethane as a reference liquid organic hydrogen carrier system from experiments and molecular simulations

Cited by 42 publications

References 70 publications

Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

Viscosity, Interfacial Tension, and Density of Binary-Liquid Mixtures of n-Hexadecane with n-Octacosane, 2,2,4,4,6,8,8-Heptamethylnonane, or 1-Hexadecanol at Temperatures between 298.15 and 573.15 K by Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

Viscosity and Surface Tension of Benzene at Saturation Conditions from Surface Light Scattering

Viscosity and Interfacial Tension of Binary Mixtures Consisting of Linear, Branched, Cyclic, or Oxygenated Hydrocarbons with Dissolved Gases Using Surface Light Scattering and Equilibrium Molecular Dynamics Simulations

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