Static Apparatus Research Articles

New static apparatus STAT9 for vapor pressure measurements at temperatures up to 463 K

In this work, a state-of-the-art static apparatus for vapor pressure measurements in a temperature range of 363−463 K and a wide pressure range of 1−13,330 Pa is introduced and described. The performance of the apparatus was evaluated by a meticulous procedure of measuring the vapor pressure of five reference materials of different volatility, anthracene, benzophenone, ferrocene, naphthalene, and dibenzothiophene. The last two compounds were studied in the blind test regime, i.e., the results were compared to literature only after finishing the experiments. During benchmarking the performance of the apparatus, it was found appropriate to develop new vapor pressure equations for ferrocene and anthracene that included high-temperature data from the STAT9 apparatus. By combining the new data with previously selected vapor pressures, sublimation enthalpies, and ideal-gas and condensed phase heat capacities, we have obtained a consistent sublimation pressure equation for anthracene and ferrocene. For anthracene, the correlation procedure covered melting properties and liquid-phase vapor pressure data to support the description of the high-temperature region. The revised vapor pressure equations and sublimation enthalpies may serve as solid foundation for future research in this field.

Phase Equilibrium Properties of Binary Systems (Furfural + Ethanol or Butan-2-ol) at Several Temperatures

The vapor pressures of the binary mixtures (furfural + ethanol) and (furfural + butan-2-ol) along with the pure component ethanol were measured using the static apparatus for VLE measurements (static device) between temperatures of 283 and 363 K. The generated results from this work were correlated using semi-empirical correlations as described by the Antoine equation. The excess Gibbs function was computed at assorted constant temperatures and applied to fit a fourth-order Redlich–Kister equation utilizing the Barker’s technique, as these two systems in study exhibited positive deviations in GE at all temperatures studied over the whole composition range. The Modified UNIFAC (Do) model, UNIQUAC model, and the NRTL model together with the Peng-Robinson-Sheng-Lu equation of state (PRSL EoS) were also employed, and excellent results were observed in the modeling of the total pressure. The Redlich–Kister equation was applied successfully for modeling the thermodynamic excess properties.

Thermodynamic study of selected aromatic monoterpenoids

Thermodynamic properties of aromatic alcohols thymol, carvacrol, and cuminol were studied in this work as part of our effort to establish reliable physicochemical data for common monoterpenes. The phase behavior of the compounds was investigated by heat-flux differential scanning calorimetry (DSC) above 183 K with a special focus on the signs of polymorphic behavior. The heat capacities of the condensed phases were determined by a Tian-Calvet type calorimeter. Vapour pressure measurements were performed using two static apparatus over a wide temperature range, including environmentally important ambient temperatures. The conformational space of the compounds was examined using density functional theory (DFT) calculations, and the ideal-gas thermodynamic properties were subsequently calculated using statistical thermodynamics. A consistent thermodynamic description is presented, which was developed using the method of simultaneous correlation that processes experimental data on phase behavior, vapor pressures, and condensed phase heat capacities together with calculated ideal-gas heat capacities. The influence of the position of the hydroxyl group on the thermodynamic properties is discussed and rationalized.

Diffusion Coefficient and Absorption of Carbonyl Sulfide in 1-Hexyl-3-methylimidazolium Bis (Trifluoromethyl) Sulfonylimide ([hmim][Tf2N

The solubility of carbonyl sulfide (COS) and also the diffusion coefficients of COS, carbon dioxide, and hydrogen sulfide were experimentally investigated in 1-hexyl-3-methylimidazolium bis(trifluoromethyl) sulfonylimide ([hmim][Tf2N]). The solubility was measured using a static apparatus, and the acid gas diffusivity was obtained by monitoring pressure drop with low initial pressure via the so-called semi-infinite volume method. All experimental absorption trials were carried out in the range of low and medium pressures and temperatures from (313.15 to 353.15) K. Furthermore, all diffusion coefficient experiments were determined at a temperature from (313.15 to 333.15) K and low pressure to some extent to be acceptable in the semi-infinite volume approach. The experimental results were correlated using the Shiflett and Yokozeki versions of the Redlich–Kwong equation of state. In addition, Henry’s law constants and the thermodynamic properties of dissolution at infinite dilution were calculated and discussed.

Vapor pressures and thermophysical properties of selected monoterpenoids II

In this work, a thermodynamic study of four enantiopure terpenoids, myrtenal, myrtenol, α-terpineol, and trans-sobrerol is presented. Vapor pressures of the selected terpenoids were determined using two static apparatus in a combined temperature range from 248 to 363 K. Heat capacities of the samples were determined by Tian-Calvet calorimetry in the temperature range from 261 to 353 K. Phase behaviour (melting temperature, fusion enthalpy, crystallization temperature, and potential polymorphic transformations) were studied using heat-flux calorimetry. Using a combination of quantum-chemical calculations and statistical thermodynamics, ideal-gas heat capacities and entropies were determined. Finally, consistency of the phase behaviour, vapor pressure, and heat capacity experimental data with the theoretically calculated data was assessed using the method of simultaneous correlation.

Volatility of monoethanolamine and tetramethylethylene diamine in aqueous solution for CO2 capture at different loading

Amine volatility is an important parameter to be considered when used as a solvent for CO2 capture. If the volatility is high, there is a need to inject the solvent so as to compensate the loss consequently the cost of the process increases. In this work CO2 solubility and amine volatility in loaded and non-loaded aqueous 30 wt% MEA (monoethanolamine), 10, 30 and 50 wt% TMEDA (N,N’,N’-tetramethylethylene diamine) were studied in the range of temperature (293 to 353 K) and pressure (2 Pa–400 kPa). Volatility measurements, in terms of partial pressures, were performed using a static apparatus with on-line analysis of the gas phase by GC to determine CO2, water and amine partial pressures above the solution. The dissolved CO2 in the liquid was determined by titration. The experimental data of the system (water + MEA), (water + TMEDA), and (water+MEA+CO2) are in a good agreement with literature data. No data for comparison were found for the system (water + TMEDA + CO2). Experimental partial pressures of the amines (PMEA and PTMEDA) were correlated using the empirical models developed by (Xu, 2011). Both models represent well the experimental data.

Effect of EPS Beads on the Behavior of Sand–EPS and Slope Stability Using Triaxial and Centrifuge Tests

The present paper is a study on the effect of expanded polystyrene (EPS) bead size on the mechanical behavior and strength parameters of Firouzkooh sand using a triaxial static apparatus. 27 triaxial (CD) tests were conducted to evaluate the effect of different factors such as EPS volumetric percentage (5%, 10%, 20%, 30%), EPS bead size, and confining pressure (100, 200, 300 kPa) on the strength parameters of the soil EPS mixture. While increasing the mixing percentage of EPS beads reduces the specific weight, the internal friction angle, the shear strength, and the initial elasticity modulus of the mixture, it increases the specimen cohesion. Specimens containing small EPS beads displayed higher internal friction angle, cohesion, shear strength, and initial elastic modulus compared with specimens containing large EPS beads. According to the results, compared with the specimens without EPS beads, a 30% addition of small and large EPS beads to the mixture increased the specimen cohesion from 0.78 to 13.8 kPa and 11.8 kPa, respectively, and reduced the friction angle by about 32% and 37%. The centrifuge tests were conducted on samples containing small EPS beads to compare the effects of the specific weight reduction and shear strength reduction parameters on the stability of the embankments. The results showed that increasing the EPS bead content increases the slip surface of failure and reduces its stability.

Mechanistic study of model drug release from HPMC matrices in fed gastric media

Modified release (MR) formulations can persist in the gastrointestinal tract (GIT) for longer periods, being exposed to many variable conditions. After food intake, the gastric motility elevates and prolonged stress on the stomach content is expected. In this study, combination of food and mechanical stress effect on the model drug (paracetamol) release from HPMC matrix tablets was studied. Dissolution tests under simulated fed conditions were performed in the paddle apparatus (USP2) and reciprocating cylinder (USP3) and compared to the biorelevant dissolution model – the advanced gastric simulator (AGS). The absence of the mechanical stress in the conventional dissolution apparatuses caused apparently higher influence of the fed media (with high fat and protein content) on dissolution rate, possibly due to the deposition of poorly soluble fed media components onto the tablet surface – a process, which is unlikely to happen in vivo. Moreover, our results also indicate that the static apparatuses may have only a poor ability to identify the less robust formulations in the presence of osmotically active ingredients in the fed media. The present study therefore demonstrates that the use of mechanically bio-relevant dissolution apparatus, like the AGS, can provide an important additional insight into the interactions between food components and HPMC matrix tablets in the stomach.

Thermodynamic study of acetamides

An extensive thermodynamic study of acetamide and its derivatives, N-methylacetamide, and N,N-dimethylacetamide, is presented in this work. Phase behavior was investigated by a heat-flux differential scanning calorimetry (DSC) from 183 K confirming the previously reported polymorphism of acetamide and N-methylacetamide. Two different polymorphic forms of N,N-dimethylacetamide were observed for the first time. Two static apparatus were employed for the vapor pressure measurements over a wide temperature range focusing on the ambient temperatures. Vapor pressures of metastable phase of acetamide were determined for the first time. Heat capacities of liquid and crystalline phases were measured by Tian-Calvet calorimetry at temperatures between 265 and 355 K. The ideal-gas thermodynamic properties were calculated using a combination of the density functional theory (DFT) and statistical thermodynamics. A consistent thermodynamic description was developed using the method of simultaneous correlation, where the experimental data for phase behavior, vapor pressures, and condensed phase heat capacities and calculated ideal-gas heat capacities are treated together to ensure overall thermodynamic consistency of the results. The observed trends in the thermodynamic properties of liquid phase were rationalized based on molecular interactions.

Experimental, Modeling and Process Simulation Studies of Ethylene Oxide Absorption

Water as an absorbent for ethylene oxide has been extensively investigated over the past decades, but many issues about this system still remain such as solvent loss, high energy consumption. In this work, a new absorbent ethylene carbonate (EC) was applied and the solubility behaviors of carbon dioxide, ethylene, methane in the ethylene carbonate (EC) were investigated with using static apparatus at temperatures of 313.2, 323.2, and 333.2 K. And the vapor liquid equilibrium(VLE) of ethylene oxide(EO) and EC have been studied with gas chromatography analysis method at temperatures of 333.2, 343.2, and 353.2 K. The NRTL and Wilson models were used to correlate experimental solubility data and VLE data. The conceptual H2O-based and EC-based EO absorption process for EO-containing mixed gas purification was established and optimized with using the regressed NRTL model parameters. The results showed that the purification process of EC used as absorbent could reduce energy consumption 37.6 Gcal/h.

A built-up-type deformable phantom for target motion control to mimic human lung respiration.

Existing human lung-mimicking requirements in various radiology application fields have led to the development of many different phantoms. However, most are static apparatus designed for equipment calibration. Although there are a few dynamic phantoms that generate predefined motions, they have complicated mechanisms that hamper even simple modifications for various lung illness simulations. As a result, existing dynamic phantoms in which a target can be embedded normally generate rectilinear target motions with limited displacement. Nevertheless, volume changes in the human lungs during normal respiration are significant, and targets inside the lungs move along various random paths depending on their location, stiffness, and the properties of the surrounding tissues. In the present work, a novel phantom design is introduced and tested. The phantom mimics the human lung motion and its deformation is initiated by a diaphragm movement. The phantom provides a fairly large deformation and the capability to adjust target motion paths. The presented device has a simple mechanism that can be easily modified to generate various pulmonary diseases. To produce a large deformation by diaphragm compressive motion, polyurethane cubic blocks constitute the deformable part of the lung phantom and a tumor made with silicone is inserted in the structure. The assembled lung part is housed within an acrylic case that is filled with water. The phantom system consists of acrylic, plastic, and low-density polyurethane to minimize artifacts when it undergoes computed tomography (CT) scans. The lung part is organized with various density polyurethane blocks, making it possible to produce nonlinear motion paths of the tumor. The lung part is deformed by a silicon film that is driven by external hydraulic pressure. A finite element method simulation and two-dimensional target motion tests were performed to verify phantom performance. The functionality of the proposed phantom system was confirmed in a series of CT images.

A Review of Technologies for Treatment of Fuel Oil during Storage and Preparation for Burning in Boiler Units’ Furnaces

The formation of nitrogen, sulfur, and carbon oxides in burning fuel oil in boiler furnaces, the elevated water content arising during unloading fuel oil from or its storage in tanks, the formation of deposits in fuel facilities' equipment during its operation, and the high cost of fuel oil are serious obstacles to the use of fuel oil as the main or backup fuel at thermal power stations (TPS). During the long-term storage of fuel oil, water partly settles and distributes in the form of lens, interlayers, or drops that are several to hundreds of micrometers in size. Water cannot be completely removed from the fuel oil by settling since the water and the fuel have nearly the same density. At present, fuel oil covers less than 2% of the fuel balance of TPSs. Considering the fact that there are regions in Russia where fuel oil is the only available fuel for boiler houses, the issues of fuel oil treatment as required for its burning or storage are urgent. Potential possibilities of the existing equipment for preparing fuel oil for burning in the form of fine water-fuel oil emulsions (WFOE) are examined, and the related performance effects are analyzed. The most promising and innovative method to produce WFOEs is the cavitation treatment of immiscible liquids. The equipment designs for cavitation treatment of viscous fluids at boiler houses and TPSs are reviewed. Preference is given to static type cavitation apparatuses featuring high capacity, reliability, and low capital and operating costs.

Patterns of lower limb muscular activity and joint moments during directional efforts using a static dynamometer

BackgroundStrength and coordination of lower muscle groups typically identified in healthy subjects are two prerequisites to performing functional activities. These physical qualities can be impaired following a neurological insult. A static dynamometer apparatus that measures lower limb joint moments during directional efforts at the foot was developed to recruit different patterns of muscular activity. The objectives of the present study were to 1) validate joint moments estimated by the apparatus, and 2) to characterize lower limb joint moments and muscular activity patterns of healthy subjects during progressive static efforts. Subjects were seated in a semi-reclined position with one foot attached to a force platform interfaced with a laboratory computer. Forces and moments exerted under the foot were computed using inverse dynamics, allowing for the estimation of lower limb joint moments.To achieve the study’s first objective, joint moments were validated by comparing moments of various magnitudes of force applied by turnbuckles on an instrumented leg equipped with strain gauges with those estimated by the apparatus. Concurrent validity and agreement were assessed using Pearson correlation coefficients and Bland and Altman analysis, respectively. For the second objective, joint moments and muscular activity were characterized for five healthy subjects while exerting progressive effort in eight sagittal directions. Lower limb joint moments were estimated during directional efforts using inverse dynamics. Muscular activity of eight muscles of the lower limb was recorded using surface electrodes and further analyzed using normalized root mean square data.ResultsThe joint moments estimated with the instrumented leg were correlated (r > 0.999) with those measured by the dynamometer. Limits of agreement ranged between 8.5 and 19.2% of the average joint moment calculated by both devices. During progressive efforts on the apparatus, joint moments and patterns of muscular activity were specific to the direction of effort. Patterns of muscular activity in four directions were similar to activation patterns reported in the literature for specific portions of gait cycle.ConclusionThis apparatus provides valid joint moments exerted at the lower limbs. It is suggested that this methodology be used to recruit muscular activity patterns impaired in neurological populations.

Thermodynamic study of selected monoterpenes IV

An extensive thermodynamic study of three monoterpenes, (−)-menthone, (+)-pulegone, and (−)-isopulegol, is presented in this work. Phase behaviour was investigated by a heat-flux differential scanning calorimetry (DSC) from 183 K resulting in detection of polymorphic behaviour of (−)-isopulegol and a noticeably slow crystallization of (+)-pulegone. Two static apparatus were employed for the vapour pressure measurements over a wide temperature range including environmentally important ambient temperatures. Heat capacities of liquid phase were measured by Tian-Calvet calorimetry at temperatures between 266 K and 353 K. Conformational space of the compounds was examined using the density functional theory (DFT) calculations and the ideal-gas thermodynamic properties were subsequently calculated using statistical thermodynamics. A consistent thermodynamic description was developed using the method of simultaneous correlation, where the experimental data for phase behaviour, vapour pressures, and condensed phase heat capacities and calculated ideal-gas heat capacities are treated together.

Experimental Research on the Vapor Pressure and Critical Parameters of Ethyl Fluoride (HFC-161)

ABSTRACT He, N.; Jiang, T., and Zhang, L., 2018. Experimental research on the vapor pressure and critical parameters of ethyl fluoride (HFC-161). In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 129–134. Coconut Creek (Florida), ISSN 0749-0208. Nowadays, many alternative refrigerants are studied for protecting ozonosphere. HFC161 is one of these refrigerants which are friendly to environment, because its Ozone Depleting Potentials (ODP) is zero. And it has a very low global warming potential, high cooling capacity and excellent energy efficiency. In present work, the vapor pressure of HFC161 has been measured using a static type apparatus over the temperature range from 233.15 K to 375.15 K, together with the vapor pressure of isobutane (HC-600a) measured in the temperature range from 275.60 K to 343.16 K for verifying the experimental apparatus. The measured vapor pressure data and those reported by other investiga...

SO2 Solubility in Low Molecular Weight Polyethylene Glycol Dimethyl Ether and Correlation using Cubic Equation of State

The solubility of sulfur dioxide (SO2) was measured in polyethelene glycol dimethyl ether (PEGDME) by use of a static type apparatus in the pressure range from 15.2 to 231.2 kPa at 308.18 K. The stated average molecular weight of PEGDME was Mw = 240 g·mol−1 and the molecular structure of the repeating unit is similar to that of dimethyl ether (DME). The bubble point pressure showed a negative deviation from Raoult law. The behavior was expected from consideration of the vapor–liquid equilibrium data of DME + SO2, reported by Noles and Zollweg (Fluid Phase Equilib 66:275–289, 1991). The ‘bridge-like structure’ will be microscopically formed between the DME unit and SO2, because the two unshared electron pairs of the oxygen atom in DME unit act as an electron donner for some molecules. The Peng–Robinson equation of state was used to correlate the experimental data. Two types of mixing rules were employed. One was a conventional model, and the other was of the excess Gibbs energy type. The latter, Wong–Sandler model combined with Flory–Huggins equation, showed a good reproducibility for the experimental data.

Diffusivity and solubility of carbonyl sulfide and sulfur dioxide in 1-ethyl-3-methylimidazolium bis (trifluoromethyl) sulfonylimide ([emim][Tf2N]): Experimental measurement and modelling

The diffusivity and solubility of carbonyl sulfide at temperatures from (313.15 to 353.15) K and pressures up to about 1.0 MPa and also the solubility of sulfur dioxide at the same temperatures and low pressures ranges in ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl) sulfonylimide ([emim][Tf2N]) were experimentally investigated. The solubility was measured using a volumetric-base static apparatus and acid gas diffusivity was obtained using the Semi-infinite volume method with low initial pressure. Using the solubility data, Henry’s law constants at different temperatures, and the partial molar thermodynamic properties of solution, that is, Gibbs energy, enthalpy, and entropy were calculated. The solubility data were correlated using 1) the generic Redlich–Kwong (GRK) cubic equation of state approaches and 2) the extended Henry’s law combined with the Pitzer’s virial expansion for the excess Gibbs energy. Finally using solubility data regression has been done with the generic Redlich–Kwong (GRK) cubic equation of state, the precision of experimental solubility data has been inspected via thermodynamic consistency test.

Experimental measurements and thermodynamic modelling of aqueous solubilities, octanol-water partition coefficients and vapor pressures of dimethyl phthalate and butyl benzyl phthalate

The aqueous solubilities, the octanol-water partition coefficients and the vapor pressures of two food contaminants (dimethyl phthalate-DMP and butyl benzyl phthalate-BBP) have been determined in this work. The aqueous solubility measured by the dynamic saturation method [298.15–328.15 K] were in the order of 10−4 mol fraction for DMP and 10−7 for BBP. The octanol-water partition coefficient is measured by using the ‘shake-flask’ method at 298.15 K. It is found that the BBP molecule is highly hydrophobic. The vapor pressure measurements carried out with the dynamic gas saturation method between 313.15 and 423.15 K, were validated with DMP vapor pressure measurements by using a static apparatus. The vapor pressures of DMP ranged from 1.4 to 1668 Pa for temperatures between 313.15 and 423.15 K, while BBP exhibits lower vapor pressures ranging from 0.014 Pa at 343.15 K to 24 Pa at 423.15 K. The experimental data determined in this work are compared with calculated properties issued from different thermodynamic models (UNIFAC, UNIQUAC, NRTL, COSMO-SAC dsp). It is found that the UNIQUAC and NRTL models can well describe the experimental aqueous solubility, while larger deviations were found for UNIFAC and COSMO-Sac dsp. The COSMO-SAC dsp model can better predict the octanol-water partition coefficient of the studied molecules than the UNIFAC model.

Polymorphism and thermophysical properties of l- and dl-menthol

The thermodynamic properties, phase behaviour, and kinetics of polymorphic transformations of racemic (dl-) and enantiopure (l-) menthol were studied using a combination of advanced experimental techniques, including static vapour pressure measurements, adiabatic calorimetry, Tian-Calvet calorimetry, differential scanning calorimetry (DSC), and variable-temperature X-ray powder diffraction. Several concomitant polymorphs (α, β, γ, and δ forms) were observed and studied. A continuous transformation to the stable α form was detected by DSC and monitored in detail using X-ray powder diffraction. A long-term coexistence of the stable crystalline form with the liquid phase was observed. The vapour pressure measurements of both compounds were performed using two static apparatus over a temperature range from 274 K to 363 K. Condensed-phase heat capacities were measured by adiabatic and Tian-Calvet calorimetry in the wide temperature interval from 5 K to 368 K. Experimental data of l- and dl-menthol are compared mutually as well as with available literature results. The thermodynamic functions of crystalline and liquid l-menthol between 0 K and 370 K were calculated from the calorimetric results. The thermodynamic properties in the ideal-gas state were obtained by combining statistical thermodynamics and quantum chemical calculations based on a thorough conformational analysis. Calculated ideal-gas heat capacities and experimental data on vapour pressure and condensed-phase heat capacity were treated simultaneously to obtain a consistent thermodynamic description. Based on the obtained results, the phase diagrams of l-menthol and dl-menthol were suggested.

Vapour-liquid equilibria, enthalpy of vaporisation, and excess Gibbs energies of binary mixtures of {3,3-diamino-N-methyldipropylamine (DNM) (or N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA)) + water}

Abstract The vapour pressures of the pure components 3,3-diamino-N-methyldipropylamine (DNM) and N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) along with the binary mixtures (DNM + water) and (PMDETA + water) were measured by means of a static apparatus at temperatures between (283 and 363) K. The data were correlated with the Antoine equation. From these data, excess Gibbs functions (GE) were calculated for several constant temperatures and fitted to four order Redlich-Kister equation using the Barker method. The binary system (DNM + water) exhibits negative deviations in GE values calculated from the vapour pressure data for all investigated temperatures and over the whole composition range. The (PMDETA + water) binary mixture shows a sinusoidal shape for GE at 283.15 K