I am a retired Army Officer and a retired academic. I was a member of the West Point faculty for 15 years and a professor of chemical engineering and dean of engineering at Cornell University for 17 years.
In recent years there has been considerable interest in the density profiles of dense monatomic f... more In recent years there has been considerable interest in the density profiles of dense monatomic fluids near solid surfaces. A natural extension of this work is to consider the density and orientational structure of a polyatomic fluid near a solid wall. As a first step in this direction we have calculated the wall-site correlation functions of symmetric hard diatomic molecules near a hard planar wall. These have been obtained from a generalization of the bulk RISM integral equation theory to the situation of a polyatomic fluid in the presence of a spherical particle whose radius is allowed to become infinite. We compare our results with Monte Carlo simulations and find qualitative agreement, although somewhat worse quantitatively than in bulk fluids. The results indicate that with increasing density and elongation, the molecules in the layer nearest to the wall increasingly prefer orientations parallel to the wall. Difficulties associated with solving the wall-RISM theory in the case of polyatomic molecules whose sites are non-equivalent are discussed. Some alternative integral equation theories for the wall-site correlation functions, suggested by variants of an approach used to derive the bulk RISM approximation, are examined and shown to be less accurate than the wall-RISM theory.
Berichte der Bunsengesellschaft für physikalische Chemie, 1983
ABSTRACT Experimental data for liquid-vapor phase compositions of Hydrogen + Ethylene are reporte... more ABSTRACT Experimental data for liquid-vapor phase compositions of Hydrogen + Ethylene are reported for 14 temperatures in the range 114.1 to 247.1 K and pressures up to 600 MPa. The data have been obtained using a vapor-recirculating apparatus suitable for measurement up to 1000 MPa. The entire region of liquid-vapor coexistence has been explored for the first time. The mixture critical line and the pressure temperature trace of the 3-phase line solid-liquid-vapor have been located. These lines intersect at 153 K and 675 MPa to form an upper critical end point. Results obtained up to 52 MPa have been compared to published data. Calculations have been made to compare the experimental results with predictions of the Peng-Robinson and Redlich-Kwong equations of state.
A heat of mixing apparatus for measuring heats of mixing of liquefied gases was designed and buil... more A heat of mixing apparatus for measuring heats of mixing of liquefied gases was designed and built. It was tested by measuring the heats of mixing of liquid nitrogen and oxygen at 77.3 K.
Following a brief discussion of the application of phase rule principles to one- and two-componen... more Following a brief discussion of the application of phase rule principles to one- and two-component phase diagrams, the three-dimensional features of several important classes of pressure-temperature-composition phase diagrams for binary mixtures are described in detail. Two- and three-phase equilibria between gas, liquid and solid phases are included in the discussion, and the emphasis is on understanding the qualitative features of three-dimensional PTX diagrams. The importance of certain features in supercritical fluid extraction is pointed out.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1976
The Monte Carlo method has been used to study a model system of 256 hard diatomic molecules, each... more The Monte Carlo method has been used to study a model system of 256 hard diatomic molecules, each consisting of two fused hard spheres of diameter sigma with centres separated by reduced distance L*=L/sigma of 0.2, 0.4 and 0.6, at densities typical of the liquid state. The orientational structure of dense, hard diatomic fluids has been studied by calculating up to sixteen terms in the expansion of the total pair correlation function g(r12,omega 1,omega 2), in spherical harmonics. The coefficients gll'm(r12) of the series have been calculated as ensemble averages in the simulation. At short distances, the system exhibits a high degree of angular correlation, which increases with increasing density and elongation; however, this correlation is relatively short ranged at all densities and elongations, and in no case is there significant angular structure at distances greater than twice the major diameter of the molecule. In the nearest neighbour shell there is a strong preference for 'T-shaped' pair orientations. At low elongations and densities the spherical harmonic coefficients are in close agreement with those predicted both by the 'blip function' theory and the solution of the Percus-Yevick equation for hard diatomics. The harmonic series for the total pair correlation function, is rapidly convergent at distances greater than L+sigma , but slowly convergent at smaller distances. The results are suitable for use as a non-spherical reference system for perturbation calculations.
In recent years there has been considerable interest in the density profiles of dense monatomic f... more In recent years there has been considerable interest in the density profiles of dense monatomic fluids near solid surfaces. A natural extension of this work is to consider the density and orientational structure of a polyatomic fluid near a solid wall. As a first step in this direction we have calculated the wall-site correlation functions of symmetric hard diatomic molecules near a hard planar wall. These have been obtained from a generalization of the bulk RISM integral equation theory to the situation of a polyatomic fluid in the presence of a spherical particle whose radius is allowed to become infinite. We compare our results with Monte Carlo simulations and find qualitative agreement, although somewhat worse quantitatively than in bulk fluids. The results indicate that with increasing density and elongation, the molecules in the layer nearest to the wall increasingly prefer orientations parallel to the wall. Difficulties associated with solving the wall-RISM theory in the case of polyatomic molecules whose sites are non-equivalent are discussed. Some alternative integral equation theories for the wall-site correlation functions, suggested by variants of an approach used to derive the bulk RISM approximation, are examined and shown to be less accurate than the wall-RISM theory.
Berichte der Bunsengesellschaft für physikalische Chemie, 1983
ABSTRACT Experimental data for liquid-vapor phase compositions of Hydrogen + Ethylene are reporte... more ABSTRACT Experimental data for liquid-vapor phase compositions of Hydrogen + Ethylene are reported for 14 temperatures in the range 114.1 to 247.1 K and pressures up to 600 MPa. The data have been obtained using a vapor-recirculating apparatus suitable for measurement up to 1000 MPa. The entire region of liquid-vapor coexistence has been explored for the first time. The mixture critical line and the pressure temperature trace of the 3-phase line solid-liquid-vapor have been located. These lines intersect at 153 K and 675 MPa to form an upper critical end point. Results obtained up to 52 MPa have been compared to published data. Calculations have been made to compare the experimental results with predictions of the Peng-Robinson and Redlich-Kwong equations of state.
A heat of mixing apparatus for measuring heats of mixing of liquefied gases was designed and buil... more A heat of mixing apparatus for measuring heats of mixing of liquefied gases was designed and built. It was tested by measuring the heats of mixing of liquid nitrogen and oxygen at 77.3 K.
Following a brief discussion of the application of phase rule principles to one- and two-componen... more Following a brief discussion of the application of phase rule principles to one- and two-component phase diagrams, the three-dimensional features of several important classes of pressure-temperature-composition phase diagrams for binary mixtures are described in detail. Two- and three-phase equilibria between gas, liquid and solid phases are included in the discussion, and the emphasis is on understanding the qualitative features of three-dimensional PTX diagrams. The importance of certain features in supercritical fluid extraction is pointed out.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1976
The Monte Carlo method has been used to study a model system of 256 hard diatomic molecules, each... more The Monte Carlo method has been used to study a model system of 256 hard diatomic molecules, each consisting of two fused hard spheres of diameter sigma with centres separated by reduced distance L*=L/sigma of 0.2, 0.4 and 0.6, at densities typical of the liquid state. The orientational structure of dense, hard diatomic fluids has been studied by calculating up to sixteen terms in the expansion of the total pair correlation function g(r12,omega 1,omega 2), in spherical harmonics. The coefficients gll'm(r12) of the series have been calculated as ensemble averages in the simulation. At short distances, the system exhibits a high degree of angular correlation, which increases with increasing density and elongation; however, this correlation is relatively short ranged at all densities and elongations, and in no case is there significant angular structure at distances greater than twice the major diameter of the molecule. In the nearest neighbour shell there is a strong preference for 'T-shaped' pair orientations. At low elongations and densities the spherical harmonic coefficients are in close agreement with those predicted both by the 'blip function' theory and the solution of the Percus-Yevick equation for hard diatomics. The harmonic series for the total pair correlation function, is rapidly convergent at distances greater than L+sigma , but slowly convergent at smaller distances. The results are suitable for use as a non-spherical reference system for perturbation calculations.
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Papers by William B Streett