Excess Internal Pressure Research Articles

Excess Thermodynamic Properties of Binary Liquid System Containing (Cyclic Ether + Octan-1-Ol) At Different Temperature

The ultrasonic velocity (u), density (ρ), and viscosity ( ) for the binary mixture 1,4-Dioxane (1) + Octan-1-ol (2) were measured over the whole composition range at temperature T = (298.15, 303.15 and 305.15) K. The experimental data have been used to calculate excess molar volume (VE), excess adiabatic compressibility ( ), excess viscosity ( ), excess intermolecular free length ( and excess internal pressure (PiE) over the entire composition range. These results have been fitted to the Redlich-Kister polynomial equation. Excess molar volume (VE), excess adiabatic compressibility ( ), excess viscosity ( ), excess intermolecular free length ( and excess internal pressure (PiE) were found to be negative for all temperatures. The results obtained have been discussed and interpreted in terms of the type and nature of the specific intermolecular interactions between the components.

Скінченно-елементна модель вертикального резервуара на жорсткій основі

This study addresses the problem of finite element modeling of a 20,000 m3 vertical steel tank subjected to static loads. The structure includes a cylindrical wall of total height 17,880 mm and diameter 39,900 mm. The shell thicknesses of the cylindrical wall are determined according to strength and buckling design standards. The geometric model is axisymmetric. The analysis involves the calculation of the stress and strain fields of the cylindrical wall and the contact zone between the flat bottom and the rigid foundation under various combinations of external loads, namely, excessive and hydrostatic pressures. The ANSYS Mechanical software is used for finite element analysis. Three-dimensional SOLID186 and SHELL281 elements are used for axisymmetric modeling of the shell structure in a three-dimensional formulation. To simulate the contact zone, CONTA174 and TARGE170 finite elements are used to model the moving contact surface of the bottom and the fixed surface of the rigid foundation, respectively. The model is verified by comparing the radial displacements calculated numerically and analytically. The discrepancy does not exceed 4%, thus evidencing the adequacy of the finite element model. The contact zone is analyzed for non-standard service conditions, such an excessive internal pressure in the tank (2.5 and 3 kPa compared to 2 kPa under normal conditions). The unilaterally constrained "bottom–foundation" contact zone model allows the bottom to detach from the foundation, thus leading to contact opening. A full detachment occurs under a certain combination of the excessive and the hydrostatic pressure. For certain liquid levels in the tank, the gap decreases, which may be due to a reduced effect of the excessive pressure. This is accompanied by the development of internal detachment caused by the increasing moment from the hydrostatic pressure. The internal detachment increases the bending moment at the wall–bottom junction, which, under certain conditions, may cause plastic deformations followed by the development of an emergency state.

A study on the extension of correlation functions obtained from molecular dynamics simulations by the Ornstein–Zernike theory for modeled molten salts

We extend the correlation functions obtained by molecular dynamics (MD) simulation for a molten salt modeled as a superposition of the Lennard-Jones (LJ) and Coulomb potentials using the hybrid closure method, which employs the Ornstein–Zernike (OZ) theory coupled with a closure relation. An appropriate distance for switching the short-range MD part and the long-range OZ part is determined by monitoring the isothermal compressibility, excess internal energy, and pressure. The Kobryn–Gusarov–Kovalenko (KGK) closure relation is mainly employed for the hybrid closure method (MD–KGK hybrid closure). The hybrid closure with either the hypernetted chain (HNC) or Kovalenko–Hirata (KH) closure was also tested to confirm that the performance was almost equivalent to one another among the MD–HNC, MD–KH, and MD–KGK methods. The bridge function for the model molten salt is extracted using the MD–KGK hybrid closure method. At a high-density state, the bridge function shows a steep increase in the repulsive core region, as is often observed for simple fluids, whereas when the density is relatively low, the bridge function for the cation–anion pair shows a downward-sloping behavior. Furthermore, the accuracies of excess internal energy, pressure, and isothermal compressibility were also examined for the HNC, KH, and KGK approximations. For molten salt systems, these approximations exhibited a similar behavior to those for monatomic LJ fluids, especially in the high-density state. The analysis of the integrand for excess internal energy and pressure is also discussed.

Studying of Acoustical Parameters of Some Binary Liquid Mixture at 303.15 K and 3 M. Hz

The ultrasonic velocity, density and viscosity of 1,4- dioxane with alkanols systems have been measured experimentally at 303.15 K over the frequency 3 M. Hz. From these three values, we have calculated thermodynamic and excess thermodynamic parameters such as adiabatic compressibility, deviation in adiabatic compressibility, molar volume excess molar volume, free length, excess free length, Viscosity, deviation in viscosity, internal pressure ,excess internal pressure, acoustic impedance, excess acoustic impedance, excess sound velocity, Rao,s constant, Wada constant, relaxation time and relaxation strength of binary liquid mixture to interpret the nature of the interactions taking place in the binary liquid mixtures. The results analyzed in the sight of molecular interaction between the components. The interaction resulting in the interstitial accommodation of 1, 4- dioxane into alkanols are the predominant factor over dipole-dipole interaction.

Finite element modelling of the contact between shell structure and foundation

This paper presents the problem of modelling of a shell structure as a vertical steel tank with a volume of 20000 cubic meters under a combination of static loads. The total height of the cylindrical wall of the tank is 17880 mm, and its diameter is 39900 mm. The wall thicknesses have been determined according to the design requirements of strength and buckling. The geometric model of the object has an axisymmetric form. The task is to perform the analysis of the stress-deformed state of the cylindrical wall and the contact zone of the wall with the foundation under different loads. The type of the contact is "Frictional" with a coefficient of friction equal to 0.45. The lower part of the foundation has been fixed. We have also restricted the radial movement of the upper part of the tank. Modelling has been carried out using the ANSYS simulation software. In three-dimensional modelling, finite elements of the SHELL281 type have been used. When solving an axisymmetric problem in a two-dimensional formulation, we have used PLANE183 finite elements. We have verified the model by comparing the radial displacements of the shell obtained using numerical simulation with the values calculated analytically. The discrepancy between the data does not exceed 5%, which indicates the adequacy of the finite element model. We have performed the analysis for non-standard operating conditions, which suppose the excessive internal pressure in the tank (2.5 and 3 kPa against 2 kPa under normal conditions). The contact "bottom - foundation" with a one-way connection allows separation of the bottom from the foundation. The complete detachment occurs under a specific combination of excessive and hydrostatic pressures. For certain levels of liquid in the tank, the gap decreases almost to zero, followed by a noticeable increase. This rapid change can be explained by the fact that with an increase in the hydrostatic pressure the effect of separation due to the excessive pressure decreases, and then the process of internal separation occurs, caused by the increasing moment from hydrostatic pressure.

Molecular interaction between ester with ethanol at different temperature using ultrasonic technique

In this work, thermodynamic and acoustic properties of binary liquid mixtures of ethyl propionate with ethanol are determined at various temperatures and under ambient pressure. Experimental ultrasonic velocity, density, and viscosity of binary mixtures were measured at different temperatures of 308 K, 313 K, 318 K, 323 K, 328 K, and 333 K. Acoustical parameters such as acoustic impedance (Z), adiabatic compressibility (βa), Intermolecular free length (Lf), relaxation time (τ), internal pressure (π), and thermodynamic parameters like Gibb’s free energy (ΔG) and enthalpy (H) have been computed from the above primary parameters. The excess free length (LfE), excess internal pressure (πE) and excess enthalpy (HE) were derived using experimental data. Negative excess values are obtained for the binary system (ethyl propionate + ethanol). The non-linear variations are found for the thermo -acoustic parameters which imply the presence of complex formation in the binary system. The obtained results have been discussed in detail.

Molecular interaction studies in binary liquid mixtures containing ethyl acetate with n-octanol at different temperatures

Abstract: Experimental values of ultrasonic velocity (u), density (ρ) and viscosity () for the binary mixture Ethyl acetate (1) + n-Octanol (2) were measured over the whole composition range at temperature T = (295.15, 298.15,301.15 and 305.15) K and at the atmospheric pressure. From the experimental data excess sound velocity (uE), excess viscosity (), excess free volume ( and excess internal pressure (PiE) were calculated. These results have been fitted to the Redlich-Kister polynomial equation. Excess viscosity (), excess free volume ( and excess internal pressure (PiE) were found to be negative for all temperatures. Excess sound velocity (uE), excess viscosity (), excess free volume ( and excess internal pressure (PiE) were plotted against the mole fraction of ethyl acetate over the whole composition range at 295.15, 298.15, 301.15 and 305.15 K. They have been analysed to discuss the nature and strength of intermolecular interactions in these mixtures.

Self-heating of viscous dampers under short- & long-duration loads: Experimental observations and numerical simulations

Similar to other energy dissipating devices, fluid viscous damper converts its input kinetic energy to heat which in turn results in temperature rise of the device. Damper self-heating may result in excessive internal pressure due to the thermal expansion of the internal fluid. Moreover, the elevated temperature might have a detrimental effect on the sealing system of the damper. In this study, two full-scale viscous dampers are tested under short- and long-duration loading protocols. A thermal camera is used to monitor temperature rise during different loads. Based on the tests of this study, the temperature rise of the considered dampers can be neglected in the case of short-duration seismic loads, but the self-heating can be significant during long-duration loading. A numerical modeling technique is also proposed by which thermal behavior of fluid viscous dampers can be thoroughly examined. Numerical simulations are able to estimate temperature of internal and external components of the damper considering different heat transfer mechanisms. Validity of the numerical results are investigated by comparing them to the results from thermal camera. Finally, energy-temperature curves are developed to estimate thermal behavior of viscous dampers during short- and long-duration loads.

Effect of Internal Pressure on Incipient Ferroelectricity of Nanoconfined Water Molecules Observed in Hydrothermally Grown Beryl Crystals

Quasistatic dielectric permittivity of D2O type I molecules (electric dipole moment perpendicular to the crystallographic c‐axis) within hydrothermally grown beryl crystals characterized by different internal pressure and content of D2O type II molecules (dipole moment parallel to the c‐axis) is measured at temperatures 4–300 K. All crystals are found to display quantum paraelectric behavior of the D2O‐I molecular subsystem permittivity, that is, permittivity growth while cooling from room temperature followed by saturation below 15–40 K. Processing the data with the Barrett expression shows that excess internal pressure and excess content of D2O‐II molecules lead to an increase in quantum temperature T1 and a decrease in the Curie constant C, with the Curie temperature TC remaining unchanged. The discovered strengthening of quantum effects (growth of T1) within an ensemble of dipole–dipole‐coupled D2O‐I molecules is associated with an enhanced azimuthal tunneling of these molecules within the hexagonal localizing potential. The data indicate the possibility of using crystal growth conditions to “tune” the strength of quantum effects in the network of polar water molecules, which provides a workbench for further studies of exotic phases of a lattice of coupled “point” electric dipoles.

A CIP-based numerical simulation of wave interaction with a fluid-filled membrane submerged breakwater

This study proposes an CIP (Constraint Interpolation Profile) viscous flow model that couples the Finite Element Method for structural deformation, to investigate the wave interaction with a fluid-filled membrane submerged breakwater. A modified ghost-cell immersed boundary method is adopted to achieve an accurate simulation of the fluid-structure interaction. After validation by published experimental data, the model is used to study the interaction between regular waves and a fluid-filled membrane submerged breakwater. The excess internal pressure, vorticity field, elastic modulus and structural responses are analyzed. The results show that, in lower excess internal pressure, the wave reflection, vortex shedding and energy dissipation are more significant. Besides, through the analysis of displacement and velocity distribution, three different vibration modes of the membrane structure are identified at different wave frequencies.

Studies of radial distribution function and second virial coefficient for surfactant decyltrimethylammonium bromide in aqueous solutions at 298.15 K: Evidence for cation–cation hydrophobic interactions effect

Excess internal pressure of solution and excess partial molar volume of solute data embedded in the parameter reversible isothermal work (W) have been used to calculate the ion–ion pair correlation functions (gij(r), r being distance) and the thermodynamic properties of aqueous solutions of decyltrimethylammonium bromide (C10TAB) in concentration range 0.01 – 0.14 mol∙kg–1. It is observed that gij(r) exhibits a peak at critical micelle concentration (cmc), while the virial coefficient term (gij(r) – 1) also goes through a maximum. Using Friedman's methodology and McMillan–Mayer theory of solutions, these results have been examined. With the help of concept of Gurney cosphere around the ions, the overlap of solvation shells (water molecules) as the concentration of ions increases have been used to probe water– structure effects as water–structure making/breaking. Coefficients Aij are estimated (Coulombic term, a core repulsive term, a cavity formation term and overlap of cosphere term) at various concentrations of ionic surfactant and at a radial distance of 20 Å for a micellar entity. Further analysis indicates that gij parameter (that is, representing cation–cation interaction g++) dominate over g+– (representing ion–solvent interaction) in solution phase. Thus for a self–assembly process (formation of micelle with aggregation number) in a solution phase is being characterized by a peak in gij(r) function at cmc and aggregation number of ≈ 38, area under the peak, while the virial coefficient variation indicates a dominance of cation–cation interaction and cosphere water–structural effects. It is emphasized that the approach adopted by us to use excess PV work to estimate gij(r) is better to understand the thermodynamic process involved in self–assemblies and micelle formation.

Analysis of H-bonded molecular association in formamide with alcohols

Ultrasonic velocity, density, viscosity, and refractive index have been measured in binary liquid mixtures of formamide with 1-propanol and 2-propanol at atmospheric pressure and 293 K, 303 K, and 313 K temperatures over the entire range of composition. Experimentally determined values have been used to calculate excess Gibb’s free energy of activation for viscous flow ‘ΔG*E’, excess internal pressure ‘πiE’, and deviation in molar refraction ‘ΔRm’. All the excess and deviated functions have been plotted against the mole fraction of formamide and calculated values have been fitted to the Redlich-Kister polynomial equation. The calculated excess values or deviation parameters have been discussed on the basis of molecular association in these binary mixtures.Further, refractive index of these liquid mixtures has been predicted using various theoretical mixing rules.

Estimation of Burst Pressure of PVC Pipe Using Average Shear Stress Yield Criterion: Experimental and Numerical Studies

Polyvinyl chloride (PVC) pipes have been extensively applied in water supply network fields. Understanding the mechanical properties and burst pressure of PVC pipes is necessary because a large number of pipes rupture due to excessive internal water pressure. In this paper, a practical approach based on the average shear stress yield (ASSY) criterion was proposed to assess the PVC pipe burst pressure. In addition, the PVC uniaxial tensile tests and the pipe burst tests were carried out to determine the material characteristic parameters and burst pressure of the PVC pipe. Furthermore, a finite element analysis (FEA) of PVC burst pressure was also performed based on the tangent intersection (TI) method to validate the proposed method and experimental results. Moreover, the impact of material parameters and pipe size, such as the strain hardening exponent and standard dimension ratio (SDR) on bursting pressure, were investigated. The comparison with the proposed theoretical model and the experimental and FEA results shows that the burst pressure derived from ASSY was consistent with the experimental data, with a relative error ranging from −2.76% to 2.65%, which is more accurate compared to other yield criteria. The burst pressure obtained by the ASSY approach declined with the increase of the hardening exponent n and increased with the increase of SDR. Therefore, the burst pressure solution-based ASSY proposed in this paper is an adequately suitable and precise predictive tool for assessing the failure pressure of PVC pipes.

Density, Ultrasonic Velocity, Isentropic Compressibility, Molar Volumes and Related Excess Parameters Studies on Ethyl Acetate with 1-Ethanol at 303K, 308K, and 313K

A binary liquid mixture that consists of ethyl acetate and 1-ethanol has been prepared at various concentrations by the mole fraction method. The ultrasonic velocity and density have been determined at 303K, 308K and 313K. From the experimental data, the excess isentropic compressibility, excess molar volumes, excess internal pressures, and excess molar enthalpy have been computed. The variations were observed as polynomial and fitted to the Redlich-Kister polynomial functions. By using this function, adjustable parameters and the standard deviations have been calculated. The experimental and theoretical data reveal that the existence of the intermolecular interactions between the selected liquid system. The partial molar compressibility’s and partial molar volume also calculated at infinite dilution of the system. In general, the intermolecular forces have tended to the variations in the magnitude and sign of the excess parameters. The excess molar volume (Vme), excess isentropic compressibility (), excess internal pressure ( ) and the enthalpy ( ) show the negative magnitude at the entire range of concentrations and temperatures. The significant variations of these parameters with the mole fraction of ethyl acetate have been analysed. Furthermore, the strength of the intermolecular interactions decreased with increasing the experimental temperatures as 303K > 308K >313K.

How coronavirus survives for hours in aerosols.

COVID (CoronaVirus Disease)-19, caused by severe acute respiratory syndrome-CoronaVirus-2 (SARS-CoV-2) virus, predominantly transmits via airborne route, as highlighted by recent studies. Furthermore, recently published titer measurements of SARS-CoV-2 in aerosols have disclosed that the coronavirus can survive for hours. A consolidated knowledge on the physical mechanism and governing rules behind the significantly long survival of coronavirus in aerosols is lacking, which is the subject of the present investigation. We model the evaporation of aerosolized droplets of diameter m. The conventional diffusion-limited evaporation is not valid to model the evaporation of small size (μm–nm) droplets since it predicts drying time on the order of milliseconds. Also, the sedimentation timescale of desiccated droplets is on the order of days and overpredicts the virus survival time; hence, it does not corroborate with the above-mentioned titer-decay timescale. We attribute the virus survival timescale to the fact that the drying of small (m–nm) droplets is governed, in principle, by the excess internal pressure within the droplet, which stems from the disjoining pressure due to the cohesive intermolecular interaction between the liquid molecules and the Laplace-pressure. The model predictions for the temporal reduction in the aerosolized droplet number density agree well with the temporal decay of virus titer. The findings, therefore, provide insight on the survival of coronavirus in aerosols, which is particularly important to mitigate the spread of COVID-19 from indoors.

Thermoacoustic Properties of Binary Liquid Mixtures of Sulfolane with Aniline, N,N-Dimethylaniline and N,N-Diethylaniline at Different Temperatures and Atmospheric Pressure

Densities and sound velocities of the binary liquid mixtures of sulfolane + aniline, sulfolane + N,N-dimethylaniline, sulfolane + N,N-diethylaniline over the whole range of composition and their pure component were measured at temperatures (T = 303.15, 308.15, 313.15 K) and atmospheric pressure. A high precision vibrating-tube densitometer was used for the measurements. From the measured values, excess adiabatic compressibility (βs E), excess sound velocity (uE), excess internal pressure (Pi E) and deviation of surface tension (Δγ) were calculated for each of the systems. The excess properties and surface tension deviation were fitted to the Redlich-Kister equation. All these properties have been discussed in terms of molecular interactions.

Thermo-Physical Properties of Heterocyclic Compounds with Aliphatic Alcohols at T = 303.15, 308.15 and 313.15 K

The densities (ρ), speeds of sound (u), and viscosities (η) have been measured for ternary liquid mixtures of tetrahydrofuran in cyclohexanone with 1-hexanol and 1-octanol at 303.15-313.15 K over the entire range of mole fractions and at atmospheric pressure 0.1 MPa. These experimental data have been used to estimate the thermophysical properties of heterocyclic compounds with aliphatic alcohols at T = 303.15, 308.15 and 313.15 K. Preliminary data was used to assess the excess free volume, internal pressure and free energy of Gibbs, which were discussed in light of the molecular interaction surviving in the mixtures. Analysis of each of the two contributions, namely interaction, free volume VE showed that the contributions are positive for all systems. The variations of these parameters with the composition and the temperature were discussed with regard to the intermolecular interactions prevailing in these mixtures. These values also indicate the formation of a hydrogen bonding (C=O......OH) between the hydrogen atom of aliphatic alcohol of 1-hexanol/1-octanol and oxygen atom of heterocyclic compounds tetrahydrofuran in cyclohexanone in the ternary liquid mixtures.

Intensification of the Foam Technology by the Energy of Electrohydrothermal Force Fields. Part 3. Investigation of the Processes of Heat and Mass Transfer in a Foam System under the Action of EHTFF

As a result of thermal expansion of the gas phase of a foam mass playing the role of compacting component in a closed volume, we observe the appearance of excess internal pressure accompanied by the formation of the fields of pressure, temperature, and moisture content. The partial flows of liquid caused by these fields are directed from the center toward the perforated walls of the form and go further leaving the form. Under the action of electrohydrothermal force fields, we observe the appearance of three partial flows of moisture combined into a single flow in the mass. Thus, the phenomenon of self-compaction is accompanied by the processes of heat and mass transfer. At low temperatures, moisture moves in the material in the form of a fluid. At the same time, at high temperatures, it has the form of vapor. The density of the total flow of moisture can be represented as the sum of densities of the partial flows. The analytic investigation of the mechanism of heat-and-mass transfer flows enables us to study the behavior of the foam mass in the course of heat-and-force treatment and to choose the best conditions for this treatment.

Intensification of foam technology by the energy of the electrohydrothermal power field. Part 3. Investigation of the processes of heat and mass transfer in the foam system under the influence of EHTPF

As a result of thermal expansion in the foam mass of the gas phase, which acts as a sealing component in a closed volume, excessive internal pressure is generated and fields of pressure, temperature, and moisture content are formed. Particular flows of liquid arising from these fields are directed from the center to the perforated walls of the form with a distance beyond it. In EHTPF, there are three partial flows of moisture that make up a single flow in the mass. Thus, self-compaction is accompanied by heat and mass transfer processes. At low temperatures, moisture moves in the material in the form of a liquid, and at high temperatures, in the form of vapor. The density of the total moisture flow can be represented as the sum of the densities of private flows. An analytical study of the mechanism of heat and mass transfer flows allows one to analyze the behavior of the foam mass during heatpower treatment and to choose the best conditions for it.

Intensification of foam technology by the energy of the electrohydrothermal force field. Part 1. Analysis of the features of generating internal pressure in the foam mass when electric current energy is introduced into it

A concept has been put forward about the potential energy inherent in the nature of the foam system to self-compact under the complex action of an electrohydrothermal force field on it. The generation of excess internal pressure in the foam system was studied analytically and experimentally. Experimental data on monitoring the dynamics of temperature and pressure were obtained using a computer and a modern electronic component base. The method inherent in the technology allows combining a number of processes in one operation: compaction of the refractory components of the mixture, removal of shrinkage moisture, stamping of any profile of a lightweight product, providing clear edges that do not require grinding and trimming of products.