Tetralin vapour pressure at elevated temperatures

Vapour pressure of tetralin was measured at elevated temperatures up to 661 K. The experimental vapour pressure data obtained from this work and the literature have been correlated by multiple regression resulting in the equation: $\text{log P =}\text{?2549}\text{T?1.022}\text{× 10}{}^{\mathrm{?3}}\text{T + 7.804}$. This equation can be used to predict tetralin vapour pressure between the normal boiling point and the critical point with maximum error of ≈3%.     

Minimum fluidization velocity at elevated temperatures and pressures

A procedure based on the Ergun equation to predict the minimum fluidization velocity at elevated temperatures and pressures and for different gaseous fluidizing agents has been discussed and shown to be applicable for practical purposes.     

Viscosity of coal tar pitch at elevated temperatures

At temperatures up to about 200 ° the viscosity of pitch, of approximately 100 °C Ring and Ball Softening Point, follows a predictable variation with temperature. Above 200 °C, variations occur depending on the source of the pitch, although a minimum viscosity is always achieved between 320 and 400 °C, followed by a rise. On heat treating at a constant temperature of 400 °C the viscosity rises. Although some preliminary work on two low-temperature pitches indicates a different regime, the work on coke-oven pitches shows a clear relation between viscosity rise and the formation of toluene- and quinoline-insolubles by what appears to be consecutive reactions from tar oils, during which the rheological behaviour becomes increasingly pseudoplastic.     

Saturated thermodynamic properties for the air-water system at elevated temperatures and pressures

A new thermodynamic model is proposed to calculate the thermodynamic properties for the air-water system in which the dry air was assumed to be a mixture of nitrogen and oxygen with the mole fractions of 0.7812 and 0.2188, respectively. For the vapor phase, fugacity coefficients were calculated with the modified Redlich-Kwong equation of state in which a new interaction parameter of oxygen and water was correlated from the experimental data of oxygen-water system. The dissolved gas followed Henry's law. Henry's constant of nitrogen was calculated with the Helgeson equation of state and that for oxygen was correlated from the experimental data of oxygen-water system. The proposed model was verified by comparing the calculated results with the available experimental data. It is shown that the proposed model is suitable for predicting saturated thermodynamic properties for the air-water system up to 300°C and . Furthermore, the prediction results of the proposed model are better than those calculated with the model of Rabinovich and Beketov (Moist Gases, Thermodynamic Properties. Begell: House, 1995), and the application range is wider than that of the model of Hyland and Wexler (ASHRAE Trans. 89(2A) (1983a, b) 500-519, 520-535) which are among the best of today's models.     

Critical temperatures and pressures and high temperature vapour pressures of seven alcohols

Critical temperatures and pressures have been determined experimentally for the four lowest n-alcohols, 2-propanol, 2-butanol, and 2-methyl-1-propanol, and are given in the penultimate line of Table 3. The last line of Table 3 lists the weighted mean critical pressures, with the corresponding critical temperatures obtained from he vapour pressure equation. Comparison with the corresponding data from standard reference books reveals deviations from the experimental data in some [2, 4] and incorrect critical pressure for ethanol in all five reference books quoted in Table 3. In addition, vapour pressure data were obtained for the same alcohols in the temperature range approaching the critical point. The measurements are reproduced by the simplified Clausius-Clapeyron equation with the constants and standard deviation given in Table 2.     

Hydrogen mass transfer in liquid hydrocarbons at elevated temperatures and pressures

The mass transfer rate of hydrogen in tetralin and hydrogenated SRC II liquid was studied in a stirred vessel at 606–684 K and 7.0–13.5 MPa. Experiments were carried out using a newly developed in-situ hydrogen probe made of semi-permeable nickel membrane. The effects of stirrer speed, liquid height to vessel diameter ratio, temperature and pressure on mass transfer rate coefficients were investigated. The experimentally determined $\text{K}{}_{\mathrm{<mtext>l</mtext>}}\text{a}$ values were correlated in terms of power input per unit volume of liquid and liquid height to vessel diameter ratio as follows: $\text{k}{}_{\mathrm{<mtext>L</mtext>}}\text{a = 3.43 × 10}{}^{\mathrm{?4}}\text{(}\text{P}\text{V}\text{)}{}^{0.8}\text{(}\text{H}\text{D}{}_{\mathrm{<mtext>T</mtext>}}\text{)}{}^{\mathrm{?1.9}}$ Furthermore, the liquid-phase mass transfer coefficient, $\text{k}{}_{\mathrm{<mtext>l</mtext>}}$, was found to be of the order of 10^?5 m s^?1 for low agitator speeds.     

An experimental investigation of minimum fluidization velocity at elevated temperatures and pressures

Minimum fluidization data at elevated temperatures and pressures are relatively scarce in the literature. This study was undertaken to provide some new data under these conditions. Minimum fluidization velocities at temperatures up to 800°K and pressures up to 5 MPa were measured for uniformly-sized glass beads with diameters between 0.2 mm and 4 mm in beds ranging in diameter from 30 mm to 50 mm. The experimental results are compared with a number of empirical correlations from the literature to determine the validity of the correlations under these elevated temperature and pressure conditions.     

Raman and infrared spectroscopic study of kerogen treated at elevated temperatures and pressures

Kerogen was treated for 24 h at temperatures of 250–700 °C and pressures of 500–1500 bar. Raman spectroscopic study of the run products documented systematic changes in both the first- and second-order spectral features with temperature and pressure. The micro-FTIR analysis of the kerogen treated showed that the presence of hydrogenated functional groups and importance of aromatic rings in the structures of the kerogen increased with temperature. An abrupt change in the chemical composition and structural state of the kerogen treated occurred at ∼500 °C.     

Estimating the burning rate of an explosive gas mixture at elevated pressures and temperatures

The flame speed has been estimated from the flow behind a shock wave from recordings of the expansion in the flame focus arising between the shock wave and the combustion front in states transitional between combustion and detonation. The result is close to the difference between the speeds of the shock wave and the mass gas flow in it and greatly exceeds the calculated velocity for a normal flame, which shows that the combustion behind the shock wave is turbulent.Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 44–48, July–August, 1992.     

Reduced kinetic mechanism for combustion of synthesis gas at elevated temperatures and pressures

The key combustion reactions of synthesis gas at elevated initial temperatures (T ₀ = 500–700 K) and pressures (p = 10–30 atm) are identified by analyzing the kinetic mechanism. A reduced mechanism of the oxidation reactions of synthesis gas consisting of 14 elementary reactions involving 13 species is proposed which adequately describes the results of experimental data on the burning velocities of mixtures of synthesis gas with oxygen and inert diluents at T ₀ = 300–700 K, p = 10–30 atm, and ratios CO/H₂ = 0.05–0.95, and satisfactorily predicts the flame structure and the dependence of the flammability limits on the initial temperature at atmospheric pressure.     

The solubility of gases and volatile liquids in polyethylene and polyisobutylene at elevated temperatures

The solubility of gases and volatile liquids in low-density polyethylene (LDPE) and polyisobutylene (PIB) at elevated temperatures has been correlated, using the experimental data available in the literature. In the present study, a Henry's constant K_p at a total pressure of approximately 1 atm defined as P₁ = K_PV, where P₁ is the partial pressure of the solute in the vapor phase and V is the solubility (cm³ solute/g polymer at 273.2 K and 1 atm), is correlated for nonpolar solutes with the following expressions: (1) For LDPE, ln(1/K_P) = ?1.561 + (2.057 + 1.438ω) (T_c/T)²; (2) For PIB, ln(1/K_p) = ?1.347 + (1.790 + 1.568ω) (T_c/T)², in which ω is the acentric factor and T_c the critical temperature of the solute. In obtaining the above correlations we have used 27 solutes covering 115 data points for LDPE, and 18 solutes covering 148 data points for PIB. We have calculated values of 1/K_p from the literature data reported in terms of the retention volume (V), weight-fraction Henry's constant (H₁), activity coefficient at infinite dilution (Ω), Flory–Huggins interaction parameter (χ), or V/P obtained from high pressure sorption experiments. The correlations obtained in this study permit one to estimate with reasonable accuracy the solubility of gases and volatile liquids in either LDPE or PIB, with information on the acentric factor (ω) and critical temperature (T_c) only. The relationship for LDPE is also applicable for solubilities in high-density polyethylene. Relationships for the heat of vaporization of solutes from infinitely dilute LDPE or PIB solutions are also derived from the temperature variation of 1/K_p.     

Speed of sound and isentropic bulk modulus of alkyl monoesters at elevated temperatures and pressures

Biodiesel is a biodegradable, sulfur-free, oxygenated, and renewable alternative diesel fuel consisting of the alkyl monoesters of FA from vegetable oils and animal fats. Biodiesel can be used in existing diesel engines without significant modifications. However, differences in physical properties between biodiesel and petroleum-based diesel fuel may change the engine's fuel injection timing and combustion characteristics. These altered physical and chemical properties also may cause the exhaust emissions and performance to differ from the optimized settings chosen by the engine manufacturer. In particular, the density, speed of sound, and isentropic bulk modulus have a significant effect on the fuel injection system and combustion. The objective of this study was to measure these three properties for biodiesel (and the pure esters that are the constituents of biodiesel) at temperatures from 20 to 100°C and at pressures from atmospheric to 32.5 MPa. Ten different biodiesel fuels, 16 different pure FA esters, three hydrocarbons, and one diesel fuel were tested. The measured values of density, speed of sound, and isentropic bulk modulus are presented. Correlations between pressure and temperature are demonstrated. Speed of sound and isentropic bulk modulus tend to increase as the degree of unsaturation increases and as the chain length increases. However, density increased with shorter chain length and decreased with saturation.     

Imaging gold clusters on TiO2(110) at elevated pressures and temperatures

Variable temperature scanning tunneling microscopy (STM) has been used to image oxide-supported nanoclusters of Au at temperatures from 300 to 450 K and oxygen pressures from 10^–10 to 4 Torr. Oxygen-induced morphological changes of the TiO₂(1×2) reconstruction are apparent at room temperature and prolonged exposure (3×10³ L (langmuir)) at 10^–4 Torr oxygen. Gold clusters with diameters smaller than 4 nm are unstable toward sintering at ca. 450 K and oxygen pressures >10^–1 Torr. Oxygen at pressures >10^–4 Torr weakens the interaction between the gold cluster and the titania support. Increasing the sample temperature to >300 K facilitates disruption of the cluster–support interaction.     

Viscosity of nitrogen gas at low temperatures up to high pressures: A new appraisal

The absolute viscosity of nitrogen gas was determined experimentally for the pressure and temperature range 1 to 150 atmospheres and 90°K to 400°K respectively. The maximum error in the data presented is believed to be better than ±1.5%, and ±1% for the high and low pressure data respectively. Two general correlating equations, one for atmospheric pressure and the other for all the available high pressure data, (i.e. densities up to 0.4 g/cc or 1.5 ρ (critical)) are presented, together with a table of recommended smoothed data, which are felt to be accurate to ±1.5% or better. Values for the low velocity collision diameter σ and maximum energy attraction functions are also presented for the low pressure data.     

Ion-based SAFT2 to represent aqueous multiple-salt solutions at ambient and elevated temperatures and pressures

Ion-based SAFT2 is extended to the properties of aqueous multiple-salt solutions at ambient and elevated temperatures and pressures. The short-range interactions between two different cations are allowed to obtain better representations of the solution properties. The adjustable parameter used in the mixing rule for the segment energy is fitted to the experimental osmotic coefficients of two-salt solutions containing one common anion at various temperatures and low pressures. The predictions of the osmotic coefficients, densities, and activity coefficients of multiple-salt solutions including brine/seawater are found to agree with experimental data.     

The critical temperatures and pressures of thirty organic compounds

Critical temperatures and pressures of some organic compounds were measured. There is good agreement between the observed critical pressures and values obtained by extrapolation of equations representing the variation of vapour pressure with temperature in the region of the normal boiling point. An incremental scheme relating critical temperatures to normal boiling points is described and is used for the correlation of the critical temperatures, obtained in this and other investigations, of more than 150 compounds.     

Solvent extraction of fatty acids from natural oils with liquid water at elevated temperatures and pressures

The use of liquid water at elevated temperatures and pressures as an extractive solvent for separating mixtures of compounds which occur in natural oils has been studied. A southern pine tall oil and a distillate from the deodorization of soybean oil were extracted with liquid water at temperatures from 298 to 312°C and pressures between 103 and 121 bar. Results indicate that water can be used to extract fatty and resin acids from crude tall oil to obtain a product with a high acid content that produces less pitch during distillation. The process can also be used to extract fatty acids from vegetable oil deodorizer distillate.     

An investigation of the viscosity of dry air at elevated pressures and temperatures using a steady-flow capillary viscosimeter

A steady-flow capillary viscosimeter, using dry air as the test gas, has been demonstrated at 150, 230, 330 and 430° Centigrade and over a pressure range of 35–150 atmospheres. Measured viscosities showed a maximum isothermal increase of about 4%. An extrapolation procedure was used to correct for flow and temperature discrepancies and a modified Hagen-Poiiseuille equation, using variables evaluated at the mean capillary temperature, was applied to those data taken under nonisothermal conditions. The overall assembly and technique are capable of relative viscosity measurements having a standard deviation within 11/2% in the cited ranges.     

Stability of acetylene/methane and acetylene/hydrogen/methane gas mixtures at elevated temperatures and pressures

Hydrogen-enriched natural gas (HENG) containing a mixture of acetylene, hydrogen, and methane is produced from natural gas feedstock in our plasma dissociation process. Storage of this HENG fuel at pressures up to 4000 psig is required for rapid vehicle refueling. Little information on the stability of acetylene mixtures at elevated pressures is presently available; therefore we have performed stability testing on gas mixtures that simulate our HENG fuel. This report describes the stability testing of binary gas mixtures of acetylene and methane containing up to 10%(v) acetylene, and a ternary gas mixture of 4%(v) acetylene, 20%(v) hydrogen, and 76%(v) methane, at pressures up to 3600 psig and temperatures up to 200 °C. The mixtures tested were found to be stable to rapid spontaneous decomposition at all test conditions; however, some degree of hydrogenation of acetylene to ethylene may have occurred in an intermediate mixture of acetylene and hydrogen while preparing the highest pressure ternary test mixture.