Investigation of the Heat Conductivity of Mutual Solutions of Methyl and Isopropyl Alcohols at Various Temperatures and Pressures

The results of an experimental study of the dependence of the heat conductivity of binary solutions of methyl and isopropyl alcohols on the concentration, temperature, and pressure are presented. An empirical equation for calculating this index is proposed.     

Investigation of the Specific Heat at Constant Pressure of Mutual Solutions of Methyl and Isopropyl Alcohols at Different Temperatures and Pressures

Results of investigation of the specific heat at constant pressure of binary solutions of methyl and isopropyl alcohols as a function of temperature, pressure, and concentration are given. The empirical equation of the concentration dependence of the specific heat at constant pressure of a methanol–propanol 2 system is proposed.     

Viscosity and Thermal Conductivity of Heavy Oils in the Region of High Temperatures and Pressures

The coefficients of dynamic viscosity and thermal conductivity of heavy high-viscosity oils (HVO) are experimentally and theoretically investigated at high temperatures and pressures. Methods are suggested for the calculation of dynamic viscosity and thermal conductivity of HVO in a wide range of parameters of state. The methods are developed on the basis of experimental data using elements of the theories of information and thermodynamic similarity of the properties of substances.     

Thermal Conductivity of Methanol–N Octanol Binary Solutions at Different Temperatures and Pressures

Results of investigation into the thermal conductivity of methanol-N octanol solutions at different temperatures, pressures, and concentrations are presented.Results of investigation into the thermal conductivity of methanol-N octanol solutions at different temperatures, pressures, and concentrations are presented.     

Viscosity of Aqueous Solutions of CO2 at High Pressures

Experimental viscosity measurements of aqueous solutions of CO₂ along three isotherms at 273, 276, and 278 K for pressures up to 30 MPa are reported. The measurements have been carried out in a falling capillary viscometer and have an estimated uncertainty of ±1.5%. The experimental values were compared with the correlation proposed by Kanti et al. derived from Flory's theory. The equation is in poor agreement with the experimental values, but the equations of Kanti et al. and of Grunberg and Nissan with one adjustable parameter yield good agreement with the experimental data.     

基于FLUENT的高压高速螺旋转子泵内部流场分析

目的分析高压高速螺旋转子泵运行过程中的内部流场行为,为高压高速螺旋转子泵的结构优化提供理论依据。方法利用Solid Works建立高压高速螺旋转子泵三维模型,使用FLUENT仿真其在高压高速运行条件下的内部流场,得到压强云图,对比有、无气穴时转速对油膜最大压强和最大负压影响。结果气穴对高压区的啮合压强基本没有影响。齿轮啮合处压强最大值、齿轮啮合处负压最大值及空气在液压油中的占有率随转速的增加而增大,当转速为12 000 r/min时,空气占有率高达12.81%,啮合处的压强可高达37.5 MPa,是出油口压强的1.5倍。结论气穴阻止了部分齿顶间隙的泄漏,对转子稳定性的提高有积极意义。最大压强出现在螺旋转子泵转子的啮合处,这使转子产生了剧烈振动,降低了螺旋转子泵的稳定性。     

Viscosity and Excess Volume at High Pressures in Associative Binaries

The dynamic viscosity and the density of three pure substances (water, 2-propanol, diacetone alcohol) and the three associated binaries were measured versus temperature T (303.15, 323.15, and 343.15 K) and pressure P. For the binary systems the mole fractions x of each component were, successively, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. For viscosity the experimental results (P100 MPa) represent a total of 540 data points: 54 for the pure substances and 486 for the binary mixtures (x0 and x1). For density the experimental results (P70 MPa) represent 1260 values: 126 for the pure substances and 1134 for the binary mixtures (x0 and x1). The mixtures with water are highly associative and the curves for the variation of with composition exhibit a maxima. The variations of the excess activation energy of viscous flow G ^E are discussed. Moreover, the measurements of are sufficiently accurate to determine the excess volumes V ^E versus pressure, temperature, and composition.     

Equation of State for <Emphasis Type="Italic">C</Emphasis><Subscript>60</Subscript> Fullerene Aqueous Solutions

In the present work PVT data of the C₆₀ fullerene aqueous solution (C₆₀ FAS) were measured as a function of the concentration of C₆₀ molecules using the variable cell method with metal bellows in the temperature range from 295 to 360 K at pressures from 0.1 to 103.2 MPa. On the liquid–vapor equilibrium line the density (ρ) of the C₆₀ FAS was measured using the pycnometer method. As a result, numerical values for the isothermal modulus of elasticity (K_T), isobaric expansivity (α_P), isothermal deviation of entropy factor (TΔS), enthalpy (ΔH), and internal energy (ΔU) have been determined. Finally, an equation of state for the C₆₀FAS was obtained for the first time.     

Viscosity and Density at High Pressures in an Associative Ternary

The dynamic viscosity and the density of the associative ternary mixture water+diacetone alcohol+2-propanol have been measured as a function of temperature T (303.15, 323.15, and 343.15 K) and pressure P (100 MPa). The experimental results correspond to 698 values of and . With reference to the 54 values previously published on pure substances and 486 values for three corresponding binaries, the system is globally described by 1188 experimental values for various values of P, T and composition. The results for are discussed in terms of excess activation energy of viscous flow.     

Thermodynamic Properties of Air from 60 to 2000 K at Pressures up to 2000 MPa

A thermodynamic property formulation for standard dry air based upon experimental P––T, heat capacity, and speed of sound data and predicted values, which extends the range of prior formulations to higher pressures and temperatures, is presented. This formulation is valid for temperatures from the solidification temperature at the bubble point curve (59.75 K) to 2000 K at pressures up to 2000 MPa. In the absence of experimental air data above 873 K and 70 MPa, air properties were predicted from nitrogen data. These values were included in the fit to extend the range of the fundamental equation. Experimental shock tube measurements ensure reasonable extrapolated properties up to temperatures and pressures of 5000 K and 28 GPa. In the range from the solidification point to 873 K at pressures to 70 MPa, the estimated uncertainty of density values calculated with the fundamental equation for the vapor is ±0.1%. The uncertainty in calculated liquid densities is ±0.2%. The estimated uncertainty of calculated heat capacities is ±1% and that for calculated speed of sound values is ±0.2%. At temperatures above 873 K and 70 MPa, the estimated uncertainty of calculated density values is ±0.5%, increasing to ±1% at 2000 K and 2000 MPa.     

Vibrational Spectra of Nitrogen in Simple Mixtures at High Pressures

Previous investigations have revealed a considerable difference between the spectral behavior of a molecule in a pure substance and that in a mixture. To gain more insight into the influence of the intermolecular interaction and of the mass of the molecules, we performed high-resolution measurements of the linewidths and peak positions of the vibrational Raman spectrum of pure nitrogen, nitrogen in argon, and nitrogen in helium. The research was carried out at room temperature and at pressures up to the melting line. It turns out that, in contrast with expectation, the linewidth as well as the frequency shift is essentially the same for pure nitrogen as for nitrogen diluted in argon, although both the mass and the potential well depth are quite different. The experimental results show the same tendency as recent computer simulations.     

The Thermal Conductivity, Thermal Diffusivity and Isobaric Heat Capacity of Toluene and Argon

This paper presents absolute measurements for the thermal conductivity and thermal diffusivity of toluene obtained with a transient hot-wire instrument employing coated wires over the density interval of 735 to 870 kgm^–3. A new expression for the influence of the wire coating is presented, and an examination of the importance of a nonuniform wire radius is verified with measurements on argon from 296 to 323 K at pressures to 61 MPa. Four isotherms were measured in toluene between 296 and 423 K at pressures to 35 MPa. The measurements have an uncertainty of less than ±0.5% for thermal conductivity and ±2% for thermal diffusivity. Isobaric heat capacity results, derived from the measured values of thermal conductivity and thermal diffusivity, using a density determined from an equation of state, have an uncertainty of ±3% after taking into account the uncertainty of the applied equation of state. The measurements demonstrate that isobaric specific heat determinations can be obtained successfully with the transient hot wire technique over a wide range of fluid states provided density values are available.     

Molar Heat Capacity at Constant Volume of n-Butane at Temperatures from 141 to 342 K and at Pressures to 33 MPa

Molar heat capacities at constant volume (C _V) for normal butane are presented. Temperatures ranged from 141 to 342 K for pressures up to 33 MPa. Measurements were conducted on liquid in equilibrium with its vapor and on compressed liquid samples. The high purity of the samples was verified by chemical analysis. For the samples, calorimetric results were obtained for two-phase [C _v ⁽²⁾ ], saturated liquid (C or C _x ), and single-phase (C _V) molar heat capacities. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded uncertainty (i.e., a coverage factor k=2 and thus a two-standard deviation estimate) for values of C _V is estimated to be 0.7%, for C _v ⁽²⁾ it is 0.5%, and for C it is 0.7%.     

Molar Heat Capacity (Cv) for Saturated and Compressed Liquid and Vapor Nitrogen from 65 to 300 K at Pressures to 35 MPa

Molar heat capacities at constant volume (C_v,) for nitrogen have been measured with an automated adiabatic calorimeter. The temperatures ranged from 65 to 300 K, while pressures were as high as 35 MPa. Calorimetric data were obtained for a total of 276 state conditions on 14 isochores. Extensive results which were obtained in the saturated liquid region (C_v⁽²⁾ and C_σ) demonstrate the internal consistency of the C_v (ρ,T) data and also show satisfactory agreement with published heat capacity data. The overall uncertainty of the C_v values ranges from 2% in the vapor to 0.5% in the liquid.     

Isochoric Heat Capacity of Heavy Water at Subcritical and Supercritical Conditions

The heat capacity of heavy water was measured in the temperature range from 294 to 746 K and at densities between 52 and 1105 kg·m^–3 using a high-temperature, high-pressure adiabatic calorimeter. The measurements were performed at 14 liquid and 9 vapor densities between 52 and 1105 kg·m^–3. Uncertainties of the measurements are estimated to be within 3% for vapor isochores and 1.5% for the liquid isochores. In the region of the immediate vicinity of the critical point (0.97T/T _c1.03 and 0.75/_c1.25), the uncertainty is 4.5%. The original C _V data were corrected and converted to the new ITS-90 temperature scale. A parametric crossover equation of state was used to represent the isochoric heat capacity measurements of heavy water in the extended critical region, 0.8T/T _c1.5 and 0.35/_c1.65. The liquid and vapor one- and two-phase isochoric heat capacities, temperatures, and saturation densities were extracted from experimental data for each measured isochore. Most of the experimental data are compared with the Hill equation of state, and the overall statistics of deviations between experimental data and the equation of state are given.     

Transport Properties of Nonelectrolyte Liquid Mixtures. XI. Mutual Diffusion Coefficients for Toluene+n-Hexane and Toluene+Acetonitrile at Temperatures from 273 to 348 K and at Pressures up to 25 MPa

Mutual diffusion coefficients,D ₁₂, have been measured at pressures up to 25 MPa using the chromatographic peak broadening technique (Taylor dispersion method) forxtoluene+(1–x)n-hexane in the temperature range 298 to 348 K and forxtoluene+(1–x) acetonitrile in the temperature range 273 to 348 K. The estimated uncertainty is ±4%. Both systems show negative deviations from straight-line behavior. The fractional decrease inD ₁₂is about 0.8% per MPa. Hard-sphere theory is applied under limiting conditions where one of the components is present in a trace amount. It is shown that the diffusion coefficients can be estimated by the Dullien method from a knowledge of the viscosity and density under the same conditions.     

The Ideal and Real Gas Heat Capacity of Potassium Atoms at High Temperatures

The ideal gas heat capacity, \(C_{p}\), of potassium atoms is calculated to high temperatures using statistical mechanics. Since there are a large number of electronic energy levels in the partition function (Boltzmann sum) below the first ionization potential, the partition function and \(C_{p}\) will become very large as the temperature increases unless the number of energy levels contributing to the partition function is constrained. Two primary categories of arguments are used to do this. First, at high temperatures, the increased size of the atoms constrains the sum (Bethe method). Second, an argument based on the existence of interacting charged species at higher temperatures is used to constrain the sum (ionization potential lowering method). When potassium atoms are assumed to constitute a real gas that obeys the virial equation of state, the lowest non-ideal contribution to \(C_{p}\) depends on the second derivative of the second virial coefficient, B(T), which depends on the interaction potential energy curves between two potassium atoms. When two ground-state (\(^{2}\hbox {S}\)) atoms interact, they can follow either of the two potential energy curves. When a \(^{2}\hbox {S}\) atom interacts with an atom in the first electronically excited (\(^{2}\hbox {P}\)) state, they can follow any of the eight potential energy curves. The values of B(T) for the ten states are determined, then averaged, and used to calculate the nonideal contribution to \(C_{p}\).     

Equation of State of He-H2 and He-D2 Dense Fluid Mixtures at High Pressures and Temperatures

The fluid variational theory is used to calculate the Hugoniot equation of state (EOS) of He, D₂, He + H₂, and He + D₂ fluid mixtures with different He:H₂ and He:D₂ compositions at high pressures and temperatures. He, H₂, and D₂ are the lightest elements. Therefore, the quantum effect is included via a first-order quantum correction in the framework of the Wigner-Kirkwood expansion. An examination of the reliability of the above computations is performed by comparing experiments and calculations, in which the calculation procedure used for He and D₂ is adopted also for He + D₂ and He + H₂, since no experimental data for the mixtures are available to conduct these comparisons. Good agreement in both comparisons is found. This result may be seen as an indirect verification of the calculation procedures used here, at least, in the pressure and temperature domains covered by the experimental data for He and D₂ used for comparisons, which is nearly up to 40 GPa and 10⁵ K. Also, the equation of state of He + H₂ fluid mixtures with different compositions is predicted over a wide range of temperatures and pressures.     

Water and Gallium at Absolute Negative Pressures. Loci of Maximum Density and of Melting

Several physical properties of liquids as well as those of the coexistence between liquid and solid can be determined at absolute negative pressures. Examples for this include thermal pressure coefficients, loci of temperature of maximum density, melting lines, speed of propagation of low-intensity sound waves, and (p, T, x) conditions of occurrence of liquid/liquid phase separation. Three model temperature-pressure cycles, which allow for the measurement of temperature-pressure conditions of the occurrence of maxima of liquid density, negatively sloped fusion lines, and the upper critical solution temperature (UCST) of liquid solutions in these metastable regimes are described. A new apparatus for measuring negative pressures was developed. The temperature and pressure are determined within an uncertainty of ±0.05°C and ±5 bar, respectively. Water and heavy water have been used as testing systems with respect to the location of their temperatures of maximum density (TMD) loci. Empirical equations of state whose parameters have been fitted to experimental data located in the normal positive pressure region have proven to extrapolate well to the negative pressure regime. Furthermore, an attempt was made to use SAFT in order to provide a more theoretically founded framework. Preliminary results for gallium have shown that a TMD exists 45 K inside the supercooled regime, and that the continuation of its melting line down to –80 bar evolves with a slope of –515±25 bar·K^–1.     

Thermodynamic Properties and Physical–Chemical Transformations of Polymer Materials at High Temperatures and Pressures

A semiempirical equation-of-state model for polymer materials over a wide range of thermodynamic parameters is proposed, allowing for the transformation of compounds at high dynamic pressures. Equations of state for polystyrene, polyimide, and poly(m-phenylene isophthalamide) are developed, and a critical analysis of calculated results in comparison with the set of available high-energy density experimental data is made.