scholarly journals Phase behavior of light gas mixtures at high pressures

1971 ◽  
Vol 40 ◽  
pp. 363-370 ◽  
Author(s):  
William B. Streett
Keyword(s):  
Phase Behavior ◽  
Structural Model ◽  
High Pressures ◽  
Fluid Layer ◽  
Gas Mixtures ◽  
Solid Surfaces ◽  
Coexisting Phases ◽  
New Hypothesis ◽  
Very High ◽  
Equal Density

If solid surfaces exist beneath the visible clouds of the major planets, they may be expected to exist at depths and pressures at which the component gas mixtures solidify under their own weight. The elucidation of phase behavior in mixtures of light gases at very high pressures is therefore essential to the solution of the problem of deep atmosphere structures in these planets. Available experimental evidence suggests several possible extrapolations of the H2-He phase diagram to high pressures. These have been used to develop a structural model for a H2-He atmosphere. In this model, gravitational separation of coexisting phases results in a layered structure, and it is shown that masses of H2-rich solid can exist in dynamic and thermodynamic equilibrium with a fluid layer of equal density but higher He content. This model forms the basis of a new hypothesis for Jupiter's Red Spot.

scholarly journals Gaseous combustion at high pressures. —Part X. The co-volume corrections, maximum temperatures and dissociation of steam and carbon dioxide in explosions

1928 ◽  
Vol 119 (782) ◽  
pp. 464-480
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Internal Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Internal Combustion ◽  
Systematic Survey ◽  
Explosion Method ◽  
Maximum Temperatures ◽  
Very High

During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.

Prediction of vapour-liquid equilibrium: Theory, computer techniques and application to permanent gas mixtures at pressures in excess of 5 bar

1977 ◽  
Vol 30 (12) ◽  
pp. 2583 ◽  
Author(s):  
CP Hicks ◽  
CL Young
Keyword(s):  
Phase Separation ◽  
Fluid Model ◽  
Gas Mixtures ◽  
Liquid Equilibrium ◽  
Equal Area ◽  
Closed Equation ◽  
Coexisting Phases ◽  
Temperature And Pressure ◽  
Two Parameter ◽  
Theory And Experiment

A technique for calculating the composition of two coexisting phases in equilibrium at a given temperature and pressure is described. The method is applicable, in principle, to any one-fluid model and any two- parameter closed equation of state. The philosophy of the technique is similar to that used in previous work on critical points.��� Values of (∂G/∂x2)T,P are calculated for mole fraction compositions ranging from zero to unity in small steps in order to locate (∂G/∂x2)T,P loops. Around each loop there is a region of phase separation and the compositions of coexisting phases are found by the usual equal-area line technique. ��� The use of the method is briefly illustrated by comparison with the experimental results for simple gas mixtures. The agreement between theory and experiment is satisfactory.

Responses of cerebral arteries and arterioles to acute hypotension and hypertension

1978 ◽  
Vol 234 (4) ◽  
pp. H371-H383 ◽  
Author(s):  
H. A. Kontos ◽  
E. P. Wei ◽  
R. M. Navari ◽  
J. E. Levasseur ◽  
W. I. Rosenblum ◽  
...  
Keyword(s):  
Pressure Range ◽  
High Pressures ◽  
Cerebral Arteries ◽  
Pial Arteries ◽  
Small Vessels ◽  
Size Dependent ◽  
Arterial Blood ◽  
Vascular Bed ◽  
Acute Hypotension ◽  
Very High

The responses of cerebral precapillary vessels to changes in arterial blood pressure were studied in anesthetized cats equipped with cranial windows for the direct observation of the pial microcirculation of the parietal cortex. Vessel responses were found to be size dependent. Between mean arterial pressures of 110 and 160 mmHg autoregulatory adjustments in caliber, e.g., constriction when the pressure rose and dilation when the pressure decreased, occurred only in vessels larger than 200 micron in diameter. Small arterioles, less than 100 micron in diameter, dilated only at pressures equal to or less than 90 mmHg; below 70 mmHg their dilation exceeded that of the larger vessels. When pressure rose to 170- 200 mmHg, small vessels dilated while the larger vessels remained constricted. At very high pressures (greater than 200 mmHg) forced dilation was frequently irreversible and was accompanied by loss of responsiveness to hypocapnia. Measurement of the pressure differences across various segments of the cerebral vascular bed showed that the larger surface cerebral vessels, extending from the circle of Willis to pial arteries 200 micron in diameter, were primarily responsible for the adjustments in flow over most of the pressure range.

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