scholarly journals Measurement of the (p, ρ, T) Behavior of Liquid MEA and DEA at Temperatures from (293.15 to 423.15) K and Pressures up to 90 MPa

2021 ◽  
Vol 42 (5) ◽  
Author(s):  
Christian W. Scholz ◽  
Roland Span
Keyword(s):  
Equations Of State ◽  
Oscillation Period ◽  
Argon Atmosphere ◽  
Relative Uncertainty ◽  
Relative Deviation ◽  
Density Measurements ◽  
Maximum Relative Deviation ◽  
Data Points ◽  
Temperature And Pressure ◽  
Mono Ethanolamine

AbstractDensities in the homogeneous liquid phase of (mono-)ethanolamine (MEA) and diethanolamine (DEA) were investigated using a commercially available high-pressure vibrating-tube densimeter (VTD). Due to the melting point of the experimental materials, the setup of the VTD had to be modified by an insulated housing of the entire piping including the pressure pump. The insulated housing could be heated up by a temperature-controlled heating fan. The liquid samples with a purity of (0.9994 or 0.9950) mole fraction, respectively, were decanted within an inert protective argon atmosphere and further degassed by several freeze–pump–thaw cycles. Density measurements were carried out at temperatures between (293, respectively, 313 and 423) K and at pressures between (5 and 90) MPa. The resulting 140, respectively, 120 (p, ρ, T) data points, explicitly extend the published database for MEA and DEA, with regards to pressure. A comparison with the currently used equations of state for MEA and DEA revealed a maximum relative deviation of – 0.18 % for MEA and – 0.41 % for DEA, each at the highest investigated temperature and pressure. Considering the measurement uncertainties in temperature, pressure, and oscillation period, as well as uncertainties resulting from the calibration and from the impurities of the sample, the combined expanded relative uncertainty (k = 2) in density varied from (0.1027 to 0.1038) % and from (0.1104 to 0.1130) %, respectively. The VTD was previously calibrated by comprehensive measurements of water and helium and had been further validated by measurements with pure propane.

scholarly journals Analytic approximation of the Debye function

2020 ◽  
Vol 49 ◽  
pp. 96-110
Author(s):  
Konstantin Vladimirovich Khishchenko ◽  
◽  
Keyword(s):  
Closed Form ◽  
High Temperatures ◽  
Equations Of State ◽  
Analytic Approximation ◽  
Thermodynamic Models ◽  
Relative Deviation ◽  
Debye Function ◽  
Limiting Behavior ◽  
Maximum Relative Deviation

An expression in a closed form is proposed for the approximation of the Debyefunction used in thermodynamic models of solids. This expression defines an analytic functionthat has the same limiting behavior as the Debye function at low and high temperatures. Theapproximation gives the maximum relative deviation from the value of the Debye function lessthan 0.001. The proposed expression can be useful in the equations of state of solids in a widetemperature range.

scholarly journals The Trouble with Venus

1971 ◽  
Vol 40 ◽  
pp. 116-127
Author(s):  
Carl Sagan
Keyword(s):  
Dielectric Constant ◽  
Chemical Composition ◽  
Surface Temperature ◽  
Rotation Axis ◽  
Order Unity ◽  
Naked Eye ◽  
Atmospheric Structure ◽  
Data Points ◽  
The Mean ◽  
Temperature And Pressure

Venus is the closest planet. Its surface has never been seen at optical frequencies; nevertheless we now know with at least fair reliability, and in some cases with remarkable accuracy, its surface temperature and pressure, its atmospheric structure, its period of rotation, the obliquity of its rotation axis, the mean surface dielectric constant, its ionospheric structure, and even a little about its surface topography. And yet the clouds of Venus, visible to the naked eye and known to be clouds since the time of Lomonsov, continue to elude our efforts to understand them comprehensively. Not only do we disagree on the chemical composition of the clouds, but it is not even settled whether they are condensation clouds or non-condensable aerosols. And yet there is a very wide variety of relevant data on the clouds. Indeed, the ratio of potentially diagnostic data points to mutually exclusive hypotheses is of the order unity.

scholarly journals The density–salinity relation of standard seawater

Ocean Science ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 15-40 ◽  
Author(s):  
Hannes Schmidt ◽  
Steffen Seitz ◽  
Egon Hassel ◽  
Henning Wolf
Keyword(s):  
North Atlantic ◽  
Equations Of State ◽  
North Atlantic Ocean ◽  
Density Measurement ◽  
Chemical Compositions ◽  
Target Uncertainty ◽  
Density Measurements ◽  
The North ◽  
Reference Equations ◽  
The North Atlantic

Abstract. The determination of salinity by means of electrical conductivity relies on stable salt proportions in the North Atlantic Ocean, because standard seawater, which is required for salinometer calibration, is produced from water of the North Atlantic. To verify the long-term stability of the standard seawater composition, it was proposed to perform measurements of the standard seawater density. Since the density is sensitive to all salt components, a density measurement can detect any change in the composition. A conversion of the density values to salinity can be performed by means of a density–salinity relation. To use such a relation with a target uncertainty in salinity comparable to that in salinity obtained from conductivity measurements, a density measurement with an uncertainty of 2 g m−3 is mandatory. We present a new density–salinity relation based on such accurate density measurements. The substitution measurement method used is described and density corrections for uniform isotopic and chemical compositions are reported. The comparison of densities calculated using the new relation with those calculated using the present reference equations of state TEOS-10 suggests that the density accuracy of TEOS-10 (as well as that of EOS-80) has been overestimated, as the accuracy of some of its underlying density measurements had been overestimated. The new density–salinity relation may be used to verify the stable composition of standard seawater by means of routine density measurements.

Synthesis and characterization of sodalite as matrix for conditioning chloride spent salts from pyroprocesses

2009 ◽  
Vol 1193 ◽  
Author(s):  
G. De Angelis ◽  
I. Bardez-Giboire ◽  
M. Mariani ◽  
M. Capone ◽  
M. Chartier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Sodium Aluminate ◽  
Argon Atmosphere ◽  
Synthesis And Characterization ◽  
Chloride Salt ◽  
X Rays ◽  
Density Measurements ◽  
Quality Product ◽  
Scanning Electron

AbstractTwo different methods have been used to synthesize sodalite for conditioning of chloride salt wastes coming from pyroprocesses: the first one, starting from kaolinite through the intermediate nepheline phase; the second one, starting from silica and sodium aluminate reagents, directly. The obtained products have been characterized by means of several analyses. In particular, different instrumental techniques – stereomicroscopy, scanning electron microscopy (SEMEDS), density measurements, thermogravimetric analysis, X-rays diffraction, FTIR spectroscopy – were performed revealing that the synthesis from kaolinite is the best method, provided that rigorous conditions are followed. The use of an argon atmosphere for the preparation of pellets of reagents is strictly necessary for the obtainment of a good quality product.

scholarly journals Group additivity calculation of the standard molal thermodynamic properties of aqueous amino acids, polypeptides and unfolded proteins as a function of temperature, pressure and ionization state

2005 ◽  
Vol 2 (5) ◽  
pp. 1515-1615 ◽  
Author(s):  
J. M. Dick ◽  
D. E. LaRowe ◽  
H. C. Helgeson
Keyword(s):  
Amino Acids ◽  
Thermodynamic Properties ◽  
Equations Of State ◽  
Reference Model ◽  
Accurate Determination ◽  
Group Additivity ◽  
Unfolded Proteins ◽  
Ionization State ◽  
Degree Of Ionization ◽  
Temperature And Pressure

Abstract. Thermodynamic calculation of the chemical speciation of proteins and the limits of protein metastability affords a quantitative understanding of the biogeochemical constraints on the distribution of proteins within and among different organisms and chemical environments. These calculations depend on accurate determination of the ionization states and standard molal Gibbs free energies of proteins as a function of temperature and pressure, which are not generally available. Hence, to aid predictions of the standard molal thermodynamic properties of ionized proteins as a function of temperature and pressure, calculated values are given below of the standard molal thermodynamic properties at 25°C and 1 bar and the revised Helgeson-Kirkham-Flowers equations of state parameters of the structural groups comprising amino acids, polypeptides and unfolded proteins. Group additivity and correlation algorithms were used to calculate contributions by ionized and neutral sidechain and backbone groups to the standard molal Gibbs free energy (Δ G°), enthalpy (Δ H°), entropy (S°), isobaric heat capacity (C°P), volume (V°) and isothermal compressibility (κ°T) of multiple reference model compounds. Experimental values of C°P, V° and κ°T at high temperature were taken from the recent literature, which ensures an internally consistent revision of the thermodynamic properties and equations of state parameters of the sidechain and backbone groups of proteins, as well as organic groups. As a result, Δ G°, Δ H°, S° C°P, V° and κ°T of unfolded proteins in any ionization state can be calculated up to T~-300°C and P~-5000 bars. In addition, the ionization states of unfolded proteins as a function of not only pH, but also temperature and pressure can be calculated by taking account of the degree of ionization of the sidechain and backbone groups present in the sequence. Calculations of this kind represent a first step in the prediction of chemical affinities of many biogeochemical reactions, as well as of the relative stabilities of proteins as a function of temperature, pressure, composition and intra- and extracellular chemical potentials of O2 and H2, NH3, H2PO4 and CO2.

AN EQUATION OF STATE FOR GASES AT LOW DENSITIES

1932 ◽  
Vol 6 (6) ◽  
pp. 596-604 ◽  
Author(s):  
D. LeB. Cooper ◽  
O. Maass
Keyword(s):  
Carbon Dioxide ◽  
Equation Of State ◽  
Equations Of State ◽  
Absolute Temperature ◽  
Viscosity Function ◽  
Temperature And Pressure ◽  
New Equation ◽  
Molecular Radius ◽  
Expanded Form ◽  
Density Results

An equation of state for gases at low densities is developed, using a new function for the change in viscosity with temperature, also developed herein.The gas law equation takes the form[Formula: see text]or V(1 + KT)(PV − RT) = λT − a where a and b are constants corresponding to those of the Van der Waals' equation, and K is a constant derived from the proposed viscosity function which is, for carbon dioxide,[Formula: see text]where K is a constant and η is the viscosity at an absolute temperature T.In the case of carbon dioxide the equation was found to follow density results with an accuracy of from 0.01% to within experimental limits, and the viscosity function was found to agree with Sutherland's (10) results between −78.5 and 20 °C.Comparisons with several other equations of state are made. These show that the new equation is probably more accurate than any other.An expanded form of the new equation, namely:[Formula: see text]permits calculations of the slopes of isothermals for any temperature. Comparisons are made with experimental data.The expanded form of the equation may be solved for K, giving the expression:[Formula: see text]where [Formula: see text] and [Formula: see text] and ξ = Rb0, and since the equation enables the calculation of the molecular radius r, the viscosity may be calculated for any temperature and pressure over which the equation holds.

Modeling Approaches to Hydration Properties of Aqueous Nonelectrolytes at Elevated Temperatures and Pressures

2008 ◽  
Vol 73 (3) ◽  
pp. 322-343 ◽  
Author(s):  
Josef Sedlbauer
Keyword(s):  
Elevated Temperatures ◽  
Equations Of State ◽  
Environmental Chemistry ◽  
Hydrothermal Systems ◽  
Organic Solutes ◽  
Hydration Properties ◽  
New Developments ◽  
Elevated Pressures ◽  
Temperature And Pressure ◽  
Temperature Correlations

Thermodynamic models describing temperature and pressure evolution of Henry's law constant and related properties of hydration of aqueous nonelectrolyte solutes are reviewed. The included models cover a broad range spanning from simple van't Hoff-like equations used in environmental chemistry over the more elaborate empirical or semiempirical temperature correlations favored for engineering purposes to complete equations-of-state for hydration properties originating in the theory of near-critical phenomena and developed for modeling of hydrothermal systems. For aqueous organic solutes, the methods are often coupled with the group additivity approximation, leading to complex tools for predicting the properties of solutions containing organic species. The various models were subjected to tests documenting their expected range of applicability at elevated pressures (for acid gases) or at high temperatures (for hydrocarbons and oxygen-containing organic solutes). New developments in the field are discussed and some future needs are envisioned.

Neural network modeling as an efficient approach to predict the density of ionic liquids/ethanol binary systems

2017 ◽  
Vol 16 (04) ◽  
pp. 1750031 ◽  
Author(s):  
Mostafa Lashkarbolooki
Keyword(s):  
Neural Network ◽  
Ionic Liquids ◽  
Binary Data ◽  
Binary Systems ◽  
Statistical Error ◽  
Percentage Error ◽  
Neural Network Modeling ◽  
Ann Model ◽  
Relative Deviation ◽  
Maximum Relative Deviation

Ionic liquids (ILs) especially their mixtures are of high interest within the different scientific societies due to their amazing properties. In this regard, a number of attempts have been made to measure, correlate, estimate and calculate the properties of ILs in the neat or mixture forms. Among the different possible predictive methods, artificial neural networks (ANNs) are widely used because of their unique and amazing capabilities for prediction of different parameters. With respect to this paper, a feed-forward ANN model is proposed to model the densities of different binary mixtures of ILs/ethanol. The proposed network is trained and tested with 1078 binary data points gathered by mining into the different published literatures. The data gathered from previously published literatures are separated into two different subsets namely training and testing. The statistical error analysis has shown that the proposed neural network correlated the binary densities with the overall mean absolute percentage error (MAPE), average relative deviation percentage error (ARD%), minimum relative deviation percent (RDmin%), maximum relative deviation Percent (RDmax%) and correlation coefficient ([Formula: see text] of 1.5%, [Formula: see text]0.1%, [Formula: see text]13.0%, 15.0% and 0.9712, respectively.

Finite Element Simulation of Bending Stress on Involute Spur Gear Tooth Profiles

2017 ◽  
Vol 30 ◽  
pp. 1-10
Author(s):  
Kolawole Adesola Oladejo ◽  
Dare Aderibigbe Adetan ◽  
Ayobami Samuel Ajayi ◽  
Oluwasanmi Oluwagbenga Aderinola
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Gear Tooth ◽  
Spur Gear ◽  
Bending Stress ◽  
Relative Deviation ◽  
Element Simulation ◽  
Maximum Relative Deviation ◽  
Bending Stresses ◽  
Good Agreement

This study investigated bending stress distribution on involute spur gear tooth profiles with pressure angle of 20 ̊ but different modules 2.5, 4.0 and 6.0 mm, using a finite-element-based simulation package - AutoFEA JL Analyzer. The drafting of the geometry for the three gear tooth profiles were implemented on the platform of VB-AutoCAD customized environment, before importing to the package. These were separately subjected to analysis for bending stresses for a point at the tooth fillet region with appropriate settings of material property, load and boundary conditions. With the same settings, the bending stresses were computed analytically using American Gear Manufacturers Association (AGMA) established equation. The results of the two approaches were in good agreement, with maximum relative deviation of 4.38%. This informed the confidence in the implementation of the package to investigate the variation of bending stress within the gear tooth profile. The simulation revealed decrease in the bending stresses at the investigated regions with increase in the module of the involute spur-gear. The study confirms that Finite element simulation of stresses on gear tooth can be obtained accurately and quickly with the AutoFEA JL Analyzer.

Sign in / Sign up

Export Citation Format

Share Document