The Experts below are selected from a list of 2190 Experts worldwide ranked by ideXlab platform
Yangxin Yu - One of the best experts on this subject based on the ideXlab platform.
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a density functional theory with a mean field weight function applications to surface tension adsorption and phase transition of a lennard jones fluid in a slit like pore
Journal of Physical Chemistry B, 2008Co-Authors: Bo Peng, Yangxin YuAbstract:A new density functional theory (DFT) for an inhomogeneous 12−6 Lennard-Jones fluid is proposed based on the modified fundamental measure theory for repulsive interaction and a weighted density functional for attractive interaction. The Helmholtz free energy functional for the attractive part is constructed using the modified Benedict−Webb−Rubin Equation of state with a mean-field weight function. Comparisons of the theoretical results with molecular simulation data suggest that the new DFT yields accurate bulk surface tension, density distributions, adsorption−desorption isotherms, pore pressures, and capillary phase transitions for the Lennard-Jones fluid confined in slitlike pores with different widths and solid-fluid interactions. The new DFT reproduces well the vapor−liquid critical temperatures of the confined Lennard-Jones fluid, whereas the mean-field theory always overestimates the critical temperatures. Because the new DFT is computationally as simple and efficient as the mean-field theory, it w...
Bo Peng - One of the best experts on this subject based on the ideXlab platform.
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a density functional theory with a mean field weight function applications to surface tension adsorption and phase transition of a lennard jones fluid in a slit like pore
Journal of Physical Chemistry B, 2008Co-Authors: Bo Peng, Yangxin YuAbstract:A new density functional theory (DFT) for an inhomogeneous 12−6 Lennard-Jones fluid is proposed based on the modified fundamental measure theory for repulsive interaction and a weighted density functional for attractive interaction. The Helmholtz free energy functional for the attractive part is constructed using the modified Benedict−Webb−Rubin Equation of state with a mean-field weight function. Comparisons of the theoretical results with molecular simulation data suggest that the new DFT yields accurate bulk surface tension, density distributions, adsorption−desorption isotherms, pore pressures, and capillary phase transitions for the Lennard-Jones fluid confined in slitlike pores with different widths and solid-fluid interactions. The new DFT reproduces well the vapor−liquid critical temperatures of the confined Lennard-Jones fluid, whereas the mean-field theory always overestimates the critical temperatures. Because the new DFT is computationally as simple and efficient as the mean-field theory, it w...
A B Meshalkin - One of the best experts on this subject based on the ideXlab platform.
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phenomenological method for construction of the liquid and gas Equation of state
Journal of Chemical & Engineering Data, 2010Co-Authors: A B Kaplun, A B MeshalkinAbstract:The semiempirical method was suggested for construction of a simple Equation of state for liquid and gas. With this purpose, some new conditions and restrictions, which should be satisfied by the “right” Equation of state, were formulated. In particular, the preferable structure of the Equation of state was determined. The Equations for description of thermodynamic properties of real gases and liquid phase were derived with involvement of additional restrictions. The second virial coefficient calculated on the basis of the modified step potential of intermolecular interactions was used as the temperature functions in the derived Equations, and the density functions were determined from analysis of experimental data. A new Equation of state for liquid and gas with six individual adjustable parameters was suggested. This new Equation describes the thermodynamic properties of substances much better than the known Benedict−Webb−Rubin Equation of state. Some caloric properties of substances were calculated.
A B Kaplun - One of the best experts on this subject based on the ideXlab platform.
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phenomenological method for construction of the liquid and gas Equation of state
Journal of Chemical & Engineering Data, 2010Co-Authors: A B Kaplun, A B MeshalkinAbstract:The semiempirical method was suggested for construction of a simple Equation of state for liquid and gas. With this purpose, some new conditions and restrictions, which should be satisfied by the “right” Equation of state, were formulated. In particular, the preferable structure of the Equation of state was determined. The Equations for description of thermodynamic properties of real gases and liquid phase were derived with involvement of additional restrictions. The second virial coefficient calculated on the basis of the modified step potential of intermolecular interactions was used as the temperature functions in the derived Equations, and the density functions were determined from analysis of experimental data. A new Equation of state for liquid and gas with six individual adjustable parameters was suggested. This new Equation describes the thermodynamic properties of substances much better than the known Benedict−Webb−Rubin Equation of state. Some caloric properties of substances were calculated.
Joseph C Oefelein - One of the best experts on this subject based on the ideXlab platform.
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on the transition between two phase and single phase interface dynamics in multicomponent fluids at supercritical pressures
Physics of Fluids, 2013Co-Authors: Rainer N Dahms, Joseph C OefeleinAbstract:A theory that explains the operating pressures where liquid injection processes transition from exhibiting classical two-phase spray atomization phenomena to single-phase diffusion-dominated mixing is presented. Imaging from a variety of experiments have long shown that under certain conditions, typically when the pressure of the working fluid exceeds the thermodynamic critical pressure of the liquid phase, the presence of discrete two-phase flow processes become diminished. Instead, the classical gas-liquid interface is replaced by diffusion-dominated mixing. When and how this transition occurs, however, is not well understood. Modern theory still lacks a physically based model to quantify this transition and the precise mechanisms that lead to it. In this paper, we derive a new model that explains how the transition occurs in multicomponent fluids and present a detailed analysis to quantify it. The model applies a detailed property evaluation scheme based on a modified 32-term Benedict-Webb-Rubin Equation of state that accounts for the relevant real-fluid thermodynamic and transport properties of the multicomponent system. This framework is combined with Linear Gradient Theory, which describes the detailed molecular structure of the vapor-liquid interface region. Our analysis reveals that the two-phase interface breaks down not necessarily due to vanishing surface tension forces, but due to thickened interfaces at high subcritical temperatures coupled with an inherent reduction of the mean free molecular path. At a certain point, the combination of reduced surface tension, the thicker interface, and reduced mean free molecular path enter the continuum length scale regime. When this occurs, inter-molecular forces approach that of the multicomponent continuum where transport processes dominate across the interfacial region. This leads to a continuous phase transition from compressed liquid to supercritical mixture states. Based on this theory, a regime diagram for liquid injection is developed that quantifies the conditions under which classical sprays transition to dense-fluid jets. It is shown that the chamber pressure required to support diffusion-dominated mixing dynamics depends on the composition and temperature of the injected liquid and ambient gas. To illustrate the method and analysis, we use conditions typical of diesel engine injection. We also present a companion set of high-speed images to provide experimental validation of the presented theory. The basic theory is quite general and applies to a wide range of modern propulsion and power systems such as liquid rockets, gas turbines, and reciprocating engines. Interestingly, the regime diagram associated with diesel engine injection suggests that classical spray phenomena at typical injection conditions do not occur.