Evaporation and Condensation Flows of a Vapor-Gas Mixture Within a Closed Rectangular Region: A Simulation Based on the System of Kinetic Equations

2007 ◽  
Author(s):  
Yoshimoto Onishi
Keyword(s):  
Transient Flow ◽  
Fluid Dynamic ◽  
Sudden Change ◽  
Kinetic Equations ◽  
Gas Mixtures ◽  
Solid Boundary ◽  
Gas Mixture ◽  
Rectangular Region ◽  
Evaporation And Condensation ◽  
Dynamic Formulation

Two dimensional transient motions of a vapor-gas mixture due to evaporation and condensation processes within a rectangular region have been considered with a view to grasping the effects of the presence of a noncondensable (inert) gas on the flow fields and their transition processes. Owing to the sudden change in temperatures of the condensed phases which are embedded in the solid boundary walls of the region, a flow takes place, and the development of this transient flow has been studied numerically based on the Boltzmann equation of BGK type for gas mixtures subject to the boundary condition of diffusive type appropriate for evaporation and condensation. The present results confirm those of the numerical analyses which have already been carried out based on the fluid dynamic formulation for binary gas mixtures established earlier in our laboratory.

Effects of the Finite Thermal Conductivity of the Condensed Phase on Evaporation and Condensation Flows of Its Vapor: Existence of the Maximum Mass and Energy Flows

2007 ◽  
Author(s):  
Yoshimoto Onishi ◽  
Takahiro Fuji ◽  
Yuuki Mannari ◽  
Takeshi Ooshida
Keyword(s):  
Thermal Conductivity ◽  
Boltzmann Equation ◽  
Condensed Phase ◽  
Fluid Dynamic ◽  
Temperature Fields ◽  
Condensed Phases ◽  
Evaporation And Condensation ◽  
Energy Flows ◽  
Internal Structures ◽  
Dynamic Formulation

Transient to steady motions of a vapor due to evaporation and condensation processes between the plane condensed phases with temperature fields as their internal structures have been studied in detail based on the new governing system at the ordinary fluid dynamic level, i.e., fluid dynamic formulation, which consists of the compressible Navier-Stokes equations and the boundary conditions appropriate for evaporation and condensation problems derived earlier from the kinetic theory analysis. The previous studies based on the Boltzmann equation of BGK type have shown that the mass and energy flows may take their maximum values at a certain value of the latent heat parameter when the condensed phases have temperature fields as their internal structures; the internal structure is a reflection of the thermal conductivity of the condensed phase being finite compared to that of its vapor. This is a striking feature in contrast to the case in which no internal structures exist in the condensed phases. Particular attention, therefore, is paid to the quantitative aspect of this behavior of the mass and energy flows. Incidentally, the comparison between the present results and the corresponding ones from the Boltzmann equation of BGK type has been made and found to be quite good, indicating that the fluid dynamic formulation works satisfactorily in the present case with temperature fields as the internal structures of the condensed phases.

scholarly journals Hydrodynamic limits of kinetic equations for polyatomic and reactive gases

2017 ◽  
Vol 8 (1) ◽  
pp. 23-42 ◽  
Author(s):  
M. Bisi ◽  
G. Spiga
Keyword(s):  
Degrees Of Freedom ◽  
Continuum Limit ◽  
Fluid Dynamic ◽  
Energy Levels ◽  
Kinetic Equations ◽  
Navier Stokes ◽  
Bgk Model ◽  
Hydrodynamic Limits ◽  
Stress Diffusion ◽  
Reactive Gases

Abstract Starting from a kinetic BGK-model for a rarefied polyatomic gas, based on a molecular structure of discrete internal energy levels, an asymptotic Chapman-Enskog procedure is developed in the asymptotic continuum limit in order to derive consistent fluid-dynamic equations for macroscopic fields at Navier-Stokes level. In this way, the model allows to treat the gas as a mixture of mono-atomic species. Explicit expressions are given not only for dynamical pressure, but also for shear stress, diffusion velocities, and heat flux. The analysis is shown to deal properly also with a mixture of reactive gases, endowed for simplicity with translational degrees of freedom only, in which frame analogous results can be achieved.

scholarly journals Fluid-dynamic equations for reacting gas mixtures

2005 ◽  
Vol 50 (1) ◽  
pp. 43-62 ◽  
Author(s):  
Marzia Bisi ◽  
Maria Groppi ◽  
Giampiero Spiga
Keyword(s):  
Fluid Dynamic ◽  
Gas Mixtures ◽  
Dynamic Equations

Composition of Mixtures of Natural Gas Components Determined by Raman Spectrometry

1980 ◽  
Vol 34 (4) ◽  
pp. 411-414 ◽  
Author(s):  
Dwain E. Diller ◽  
Ren Fang Chang
Keyword(s):  
Natural Gas ◽  
Mole Fraction ◽  
Gas Mixtures ◽  
Spectrometric Method ◽  
Gas Mixture ◽  
Raman Intensity ◽  
Raman Spectrometry ◽  
Intensity Measurements ◽  
Hydrocarbon Gas ◽  
Related Line

The feasibility of using Raman spectrometry for determining the composition of mixtures of natural gas components was examined. Raman intensity measurements were carried out on eight, gravimetrically prepared, binary gas mixtures containing methane, nitrogen, and isobutane at ambient temperature and at pressures to 0.8 MPa. The repeatability of the molar intensity ratio, ( I2/ y2)/( I1/ y1), where y1 is the concentration of component 1 in the mixture, and I1 is the intensity of the related line in the mixture spectrum, was examined. The compositions of two gravimetrically prepared methane-nitrogen-isobutane gas mixtures were determined spectrometrically with an estimated precision of about 0.001 in the mole fraction. Typical differences from the gravimetric concentrations were less than 0.002 in the mole fraction. The Raman spectrum of a gravimetrically prepared, eight component, hydrocarbon gas mixture was obtained to show that the Raman spectrometric method has potential for being applicable to natural gas type mixtures.

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