Surface Light Scattering Research Articles

Experimental investigation and correlations of thermophysical properties for bio-aviation kerosene surrogate containing n-decane with ethyl decanoate and ethyl dodecanoate

Physical fuel surrogate is always necessary to be proposed to match physical properties such as liquid density, viscosity and surface tension of the real bio-aviation kerosene for the characteristics of their spray performance. Thus, it is crucial to determine the related thermophysical properties over a wide temperature range for a further development of the fuel spray system. Therefore, binary surrogates of n-decane with ethyl decanoate and ethyl dodecanoate were proposed and their thermophysical properties were investigated in the present work. The liquid density was obtained using a U-tube densimeter in the temperature range between (293.15 and 433.15) K. The liquid kinematic viscosity and surface tension were investigated simultaneously by surface light scattering (SLS) method in the temperature range from (313 to 423) K. Additionally, the refractive index was measured by a refractometer in the temperature range from (278.15 to 358.15) K. Furthermore, correlations for these properties were developed as the function of mole fraction and temperature. The relative deviations of experimental liquid density, kinematic viscosity, surface tension and refractive index from those calculated according to the correlations were within the range of ±0.2%, ±2%, ±1% and ±0.08%, respectively.

Characterization of Long Linear and Branched Alkanes and Alcohols for Temperatures up to 573.15 K by Surface Light Scattering and Molecular Dynamics Simulations.

This work contributes to the characterization of long linear and branched alkanes and alcohols via the determination of their thermophysical properties up to temperatures of 573.15 K. For this, experimental techniques including surface light scattering (SLS) and molecular dynamics (MD) simulations were used under equilibrium conditions to analyze the influences of chain length, branching, and hydroxylation on liquid density, liquid viscosity, and surface tension. For probing these effects, 12 pure model systems given by the linear alkanes n-dodecane, n-hexadecane, n-octacosane, n-triacontane, and n-tetracontane, the linear alcohols 1-dodecanol, 1-hexadecanol, and 1,12-dodecanediol, the branched alkanes 2,2,4,4,6,8,8-heptamethylnonane (HMN) and 2,6,10,15,19,23-hexamethyltetracosane (squalane), and the branched alcohols 2-butyl-1-octanol and 2-hexyl-1-decanol were investigated 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 surface tensions with average expanded uncertainties (k = 2) of 0.061, 2.1, and 2.6%, respectively, the performance of the three commonly employed force fields (FFs) TraPPE, MARTINI, and L-OPLS was assessed in MD simulations. To improve the simulation results for the best-performing all-atom L-OPLS FF at larger temperatures, a modified version was suggested. This incorporates a temperature dependence for the energy parameters of the Lennard-Jones potential obtained by calibrating only against the experimental liquid density data of n-dodecane. By transferring this approach to all other systems studied, the modified L-OPLS FF shows now a distinctly better representation of the equilibrium and transport properties of the long alkanes and alcohols, especially at high temperatures.

Liquid surface tension, kinematic viscosity, density and refractive index of the binary mixtures of n-hexadecane with methyl butyrate and methyl decanoate close to saturation conditions

To facilitate the application of clean alternative fuels or fuel additives in compression ignition engines and a better understanding of the characteristics of their combustion and emission, physical biofuel surrogates are necessary to be proposed in computation and the knowledge of their thermophysical properties, such as liquid density, surface tension and viscosity, are also crucial for the design and optimization of the fuel injection system. Therefore, the surface light scattering (SLS) method was adopted for the simultaneous determination of the liquid surface tension and kinematic viscosity of the binary mixtures containing n-hexadecane, methyl butyrate and methyl decanoate in the temperature range between (353.15 and 423.15) K in the present work. Additionally, a U-tube densimeter and refractometer were used to obtain the liquid density and refractive index of the binary mixtures in the temperature range from (293.15–423.15) K and (293.15–358.15) K, respectively. Correlations for all thermophysical properties against temperature and mole fraction were also proposed. The relative deviations of liquid density, refractive index, kinematic viscosity as well as surface tension data from those calculated by the proposed equations were within ±0.3%, ±0.20%, ±2% and ±1%, respectively for the binary systems.

Experimental Investigation of the Thermophysical Properties of the Bio-Aviation Fuel Surrogates: Binary and Ternary Mixtures of n-Dodecane, Methyl Butyrate, and Methyl Decanoate

For the investigation of injection characteristics of fuels in the internal combustion engines or turbines, thermophysical properties like liquid kinematic viscosity, surface tension, density, and refractive index are crucial and necessary. In this work, the liquid kinematic viscosity and surface tension were measured by surface light scattering (SLS) for the binary and ternary mixtures of n-dodecane with methyl butyrate and methyl decanoate, respectively, in the temperature ranges from (308.15 to 413.15) K for the mixtures and (298.15 to 423.15) K for methyl butyrate. Additionally, the liquid density was determined by a U-tube densimeter from (293.15 to 423.15) K, and refractive index was measured from (278.15 and 358.15) K. Furthermore, the experimental data of surface tension and kinematic viscosity for the mixtures were correlated with two proposed equations against the temperatures and mole fractions. The density and refractive index data were correlated by polynomial functions. This work provides essential data and correlation models for the crucial thermophysical properties of the binary model fuels for the bio-aviation kerosene in connection with the investigation of the fuel injection and combustion system.

Liquid Viscosity and Surface Tension of n-Hexane, n-Octane, n-Decane, and n-Hexadecane up to 573 K by Surface Light Scattering (SLS).

In the present study, the simultaneous and accurate determination of liquid viscosity and surface tension of the n-alkanes n-hexane (n-C6H14), n-octane (n-C8H18), n-decane (n-C10H22), and n-hexadecane (n-C16H34) by surface light scattering (SLS) in thermodynamic equilibrium is demonstrated. Measurements have been performed over a wide temperature range from 283.15 K up to 473.15 K for n-C6H14, 523.15 K for n-C8H18, and 573.15 K for n-C10H22 as well as n-C16H34. The liquid dynamic viscosity and surface tension data with average total measurement uncertainties (k = 2) of (2.0 and 1.7) % agree with the available literature and contribute to a new database at high temperatures. Over the entire temperature range, a Vogel-type equation for the dynamic viscosity and a modified van der Waals equation for the surface tension represent the measured data for the four n-alkanes within experimental uncertainties. By also considering our former SLS data for n-dodecane (n-C12H26) and n-octacosane (n-C28H58), empirical models for the liquid viscosity and surface tension of n-alkanes were developed as a function of temperature and carbon number covering values between 6 and 28. Agreement between these models and reference correlations for further selected n-alkanes which were not included in the development procedure was found.

Interfacial Tension and Liquid Viscosity of Binary Mixtures of n-Hexane, n-Decane, or 1-Hexanol with Carbon Dioxide by Molecular Dynamics Simulations and Surface Light Scattering

In the present study, the interfacial tension and liquid viscosity of binary mixtures of n-hexane, n-decane, or 1-hexanol with carbon dioxide (CO2) were investigated by molecular dynamics (MD) simulations and surface light scattering (SLS). The latter technique was applied to study experimentally the influence of dissolved CO2 on the interfacial tension and liquid viscosity of binary mixtures of n-hexane with CO2 at 303.15 K and saturation pressures up to 5 MPa corresponding to a CO2 mole fraction in the liquid phase up to 0.75. For this system at vapor–liquid equilibrium, the liquid viscosity and interfacial tension were determined with average relative expanded uncertainties (k = 2) of (1.8 and 1.3) %. In equilibrium MD simulations for binary mixtures of n-hexane, n-decane, or 1-hexanol with CO2, the vapor–liquid equilibria including saturated densities as well as the interfacial tensions were predicted at temperatures of (303.15, 333.15, and 363.15) K for CO2 mole fractions in the liquid phase up to 0.52. For the binary mixtures of n-hexane with CO2, agreement between the measured and simulated data for viscosity and interfacial tension was found. With the three mixtures investigated by MD simulations, the influence of chain length and hydroxylation on the interfacial tension could be demonstrated. The simulations showed that the magnitude of CO2 enrichment at the vapor–liquid interface is more pronounced for solvents with larger surface tensions.

Experiment and correlation of the thermophysical properties for binary and ternary liquid mixtures of three fatty acid ethyl esters and n-dodecane

In present study, surface light scattering (SLS) was used for the simultaneous determination of liquid surface tension and kinematic viscosity of the binary and ternary mixtures of three fatty acid ethyl esters (FAEEs) and n-dodecane. The SLS apparatus was firstly checked with n-dodecane and a good agreement between our data and those from literatures could be found. By utilizing this apparatus, both properties were investigated in the temperature ranges between (308 and 413) K. Additionally, the liquid density and refractive index were determined by a densimeter between (293 and 423) K and a refractometer from (278 to 358) K, respectively. The thermophysical property data obtained in this study were correlated as polynomial equations of temperature and mole fraction of the pure components. This work provided the crucial thermophysical properties and the corresponding models in connection with the application in the design and optimization of the injection system of internal combustion engine (ICE).

Set-up of the cryogenic phase equilibria test stand CryoPHAEQTS

The design of processes using cryogenic fluid mixtures requires fluid property data, which is unavailable today. In particular, this data is crucial to develop cryogenic mixed-refrigerant cycles for high-temperature superconductor (HTS) applications and to further optimize hydrogen liquefaction processes. CryoPHAEQTS, which is currently being built at KIT, will provide physical property data for fluid mixtures in a temperature range of 15–300K and at pressures up to 15 MPa, including also mixtures with either flammable or oxidizing components (e.g. hydrogen, deuterium, oxygen). By direct sampling from an equilibrium cell, vapor-liquid equilibria (VLE) and vapor-liquid-liquid equilibria (VLLE) can be determined using gas chromatography. Solid-liquid equilibria (SLE) are measured using a calorimetric method. The measurement of heat capacities is implemented by combining two different flow measurement principles. In addition, the test stand offers optical access for a future upgrade with an optical measurement system that allows in-equilibrium measurements of both bulk transport properties by dynamic light scattering (DLS) and surface tension by surface light scattering (SLS).

Thermophysical properties of fatty acid methyl and ethyl esters

In present study, surface light scattering (SLS) was used for the simultaneous determination of liquid surface tension and kinematic viscosity of twelve fatty acid esters, including six methyl esters (FAMEs) and six ethyl esters (FAEEs). The SLS apparatus was firstly checked with a reference fluid n-dodecane, and a good agreement of our data from SLS with those from literatures could be found. By utilizing this apparatus, both properties were investigated in the temperature ranges between (298 and 448) K for all substances with an exception of methyl myristate and ethyl myristate covering the temperatures between (323 and 448) K due to their high melting points. Additionally, the liquid density and refractive index were determined by an Anton Paar U-tube densimeter between (293 and 453) K and a refractometer from (278 to 358) K, respectively. The surface tension and viscosity data obtained from the SLS experiment were fitted to the van der Waals type and the reciprocal temperature-dependent polynomial equations, respectively. The quadric and linear functions were adopted to correlate the density and refractive index data, respectively. This work improves the data situation for these fatty acid esters especially at elevated temperatures and provides necessary data and models for the crucial thermophysical properties in connection with the design and optimization of the injection system of an internal combustion engine (ICE).

Liquid Viscosity and Interfacial Tension of Binary and Ternary Mixtures Containing n-Octacosane by Surface Light Scattering

In this study, the liquid viscosity and interfacial tension of binary and ternary mixtures containing n-octacosane (n-C28H58) and different byproducts typically found in the Fischer–Tropsch process...

Interfacial tensions and viscosities in multiphase systems by surface light scattering (SLS)

Multiphase systems are relevant in many fields of process engineering. For process and product design in connection with multiphase systems, knowledge on the thermophysical properties of the individual phases such as viscosity and on the interfacial tension between these is required but often lacking in literature. In the present study, the applicability of surface light scattering (SLS) for the simultaneous measurement of interfacial tensions and viscosities in multiphase systems in macroscopic thermodynamic equilibrium is demonstrated. For two model systems consisting of n-decane and methanol as well as n-dodecane and methanol forming a vapor-liquid-liquid equilibrium at atmospheric pressure, surface fluctuations which show an oscillatory behavior at the vapor-liquid and liquid-liquid interface could be associated with hydrodynamic modes. From an exact theoretical description of the dynamics of the surface fluctuations, absolute data for the dynamic viscosities of the two liquid phases as well as the vapor-liquid and liquid-liquid interfacial tensions could be determined at temperatures between (333 and 358) K with total measurement uncertainties (k = 2) down to about 2%. For both systems studied at temperatures close to the upper critical solution temperature, the viscosities of the two liquid phases approach each other and the liquid-liquid interfacial tension tends to zero.

Viscosity and Surface Tension of Branched Alkanes 2-Methylnonane and 4-Methylnonane

The liquid viscosity, surface tension, and liquid density of the two branched alkanes 2-methylnonane and 4-methylnonane were studied for temperatures between 283.15 and 448.15 K. The surface tension and liquid dynamic viscosity were obtained from surface light scattering (SLS) measurements close to saturation conditions with average relative expanded uncertainties (k = 2) of 1.5 and 0.9 %. Two vibrating-tube densimeters were used for the measurement of the liquid density at atmospheric pressure with relative expanded uncertainties (k = 2) between 0.01 and 0.5 %. The measured data could be correlated mostly within their expanded uncertainties by appropriate equations. Comparison with the few available literature data shows good agreement.

Subjective Visual Performance and Objective Optical Quality With Intraocular Lens Glistening and Surface Light Scattering.

To evaluate the long-term effect of glistenings and surface light scattering of intraocular lenses (IOLs) on visual and optical performance after cataract surgery. Pseudophakic eyes that underwent standard phacoemulsification and two types of hydrophobic acrylic spherical IOL implantation without complications for at least 5 years were included in this retrospective study. Participants were divided into the glistenings, surface light scattering, and control groups according to the current condition of the IOLs. Then participants received a follow-up examination including uncorrected and corrected distance visual acuity (UDVA and CDVA), contrast sensitivity, straylight, and intraocular higher order aberrations, as well as point spread function (PSF) and modulation transfer function (MTF). A total of 140 eyes were included in the study. UDVA, CDVA, and glare sensitivity were not significantly different among the three groups (P > .05). However, compared with the control group, the IOLs of the glistenings and surface light scattering groups were associated with significantly lower contrast sensitivity under no glare conditions. Furthermore, eye with glistenings exhibited the highest straylight value (P < .05), whereas no difference was found between the surface light scattering and control groups. In contrast to the control group, the spherical aberration increased and the mean values of PSF and MTF decreased in the glistenings and surface light scattering groups. Both glistenings and surface light scattering tend to impair subjective visual performance, such as contrast sensitivity, and potentially affect objective optical quality, including straylight, spherical aberration, PSF, and MTF. [J Refract Surg. 2018;34(6):372-378.].

Saturated Liquid Dynamic Viscosity and Surface Tension of trans-1-Chloro-3,3,3-trifluoropropene and Dodecafluoro-2-methylpentan-3-one

A surface light scattering (SLS) method was applied to investigate the saturated liquid dynamic viscosity and surface tension of trans-1-chloro-3,3,3-trifluoropropene (R1233zd(E)) and dodecafluoro-2-methylpentan-3-one (also known as Novec1230 and Novec649) at a temperature range from 303 to 403 K and 303 to 433 K, respectively. The typical expanded uncertainty (k = 2) of the saturated liquid dynamic viscosity and surface tension is 3% and 1.5%, respectively. The liquid viscosity and surface tension were correlated with a simple polynomial equation and van der Waals equation, respectively.

Liquid Viscosity and Surface Tension of n-Dodecane, n-Octacosane, Their Mixtures, and a Wax between 323 and 573 K by Surface Light Scattering

The present contribution provides experimental data for the liquid viscosity and surface tension of n-alkane based model systems at temperatures up to 573 K. The fundamental advantage of the used surface light scattering (SLS) method lies in its application in thermodynamic equilibrium without calibration in a contactless way. The investigated systems comprise the pure fluids n-dodecane (n-C12H26) and n-octacosane (n-C28H58), their binary mixture at a n-C12H26 mole fraction of about 0.3, and the commercially available hydrocarbon wax SX-70 representing a multicomponent mixture of n-alkanes with a broad chain length distribution. For the first time, it could be demonstrated that the SLS method can simultaneously access the liquid viscosity and surface tension of such medium- to long-chained n-alkane systems close to saturation conditions over a broad temperature range from 323 to 573 K. Typical measurement uncertainties of 2% based on a coverage factor k = 2, i.e., a level of confidence of more than 95%, were obtained. Over the entire temperature range, a simple polynomial equation for the dynamic viscosity and a modified van der Waals equation for the surface tension represent the measured data of the pure and binary systems well. The present investigations improve the data situation for hydrocarbon systems in the high-temperature range where no measurement results exist in literature.

Surface Tension and Liquid Viscosity of R32+R1234yf and R32+R1234ze

The surface tension and liquid viscosity of two binary refrigerant mixtures 1,1,1,2-tetrafluoroethane (R32) (1) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) (2) and R32 (1) + trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze) (2) have been measured from 293 K to the critical point by using the surface light scattering (SLS) method. The experimental data were correlated as a function of temperature and mole fraction of the pure components. For the surface tension of R32+R1234yf and R32+R1234ze, the average absolute deviations are 0.053 and 0.029 mN·m–1, respectively. As for the liquid viscosity, the relative percentage average absolute deviations are 0.86 and 1.01%, respectively.

Surface tension and liquid viscosity measurement for binary mixtures of R134a with R1234yf and R1234ze(E)

The surface tension and liquid kinematic viscosity of two binary refrigerant mixtures 1,1,1,2-tetrafluoroethane (R134a) (1) +2,3,3,3-tetrafluoroprop-1-ene (R1234yf) (2) and R134a (1) + trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(E)) (2) were measured in the temperature range from 293 K up to the liquid–vapor critical point with the surface light scattering (SLS) method. The experimental data were correlated as a function of temperature and mole fraction of the pure components. For surface tension, the average absolute deviations are 0.019 mN∙m−1 for R134a + R1234yf and R134a + R1234ze(E). For liquid viscosity, the average absolute deviations are 0.96% and 1.16% for R134a + R1234yf and R134a + R1234ze(E), respectively.

Density, Surface Tension, and Kinematic Viscosity of Hydrofluoroethers HFE-7000, HFE-7100, HFE-7200, HFE-7300, and HFE-7500

The liquid density, liquid kinematic viscosity, and surface tension of the segregated hydrofluoroethers (HFEs) HFE-7000 (1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane), HFE-7100 (mixture of the isomers 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane and 1,1,1,2,3,3-hexafluoro-3-methoxy-2-(trifluoromethyl)propane), HFE-7200 (mixture of the isomers 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane and 1-ethoxy-1,1,2,3,3,3-hexafluoro-2-(trifluoromethyl)propane), HFE-7300 (1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane), and HFE-7500 (3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl)hexane) were studied in dependence on temperature under saturation conditions. A vibrating-tube densimeter was used for the measurement of the saturated-liquid density at temperatures from (273.15 to 363.15) K with a relative expanded uncertainty (k = 2) of 0.02 %. The kinematic viscosity of the liquid phase and surface tension were obtained on the basis of surface light scattering (SLS) measurements for...

Surface tension and liquid viscosity measurement of ethyl fluoride (R161) under saturation condition

Surface light scattering (SLS) has been used for the simultaneous determination of surface tension and liquid kinematic viscosity of ethyl fluoride (R161) under saturation conditions in the temperature ranges between 293K and very close to the critical temperature with the expanded uncertainties(k=2) of ±2% for the liquid kinematic viscosity and ±1.5% for the surface tension. In addition, the surface tension of R161 was also measured over the temperature range from (244 to 334)K using the differential capillary rise method. All the surface tension and viscosity results were correlated as a function of temperature, and the average absolute deviations between the experimental and calculated values were 0.04mNm−1 and 1.11%, respectively.

Evaluation of the Si0.8Ge0.2-on-Si Epitaxial Quality by Inline Surface Light Scattering: A Case Study on the Impact of Interfacial Oxygen

Inline light scattering measurements are frequently used to determine wafer quality and cleanliness. In this paper we will show how this technique can be extended to determine the crystalline quality after hetero-epitaxy. Misfits on the surface of the epitaxial layer cause increased surface light scattering. The Si0.8Ge0.2-on-Si epitaxial quality has been evaluated by surface light scattering. A correlation is observed with the controlled variation of the interfacial oxygen between the Si substrate and epitaxial Si0.8Ge0.2.