The axisymmetric and plane cases of a gas phase steadily displacing a Newtonian liquid—A simultaneous solution of the governing equations

1997 ◽  
Vol 9 (8) ◽  
pp. 2420-2428 ◽  
Author(s):  
Marı́a D. Giavedoni ◽  
Fernando A. Saita
Keyword(s):  
Gas Phase ◽  
Newtonian Liquid ◽  
Simultaneous Solution ◽  
Governing Equations

Analysis of Heat and Mass Transfer Between a Desiccant-Air System in a Packed Tower

1987 ◽  
Vol 109 (2) ◽  
pp. 89-93 ◽  
Author(s):  
P. Gandhidasan ◽  
M. Rifat Ullah ◽  
C. F. Kettleborough
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Heat And Mass Transfer ◽  
Packing Material ◽  
Mass Transfer Resistance ◽  
Liquid Desiccant ◽  
Governing Equations ◽  
Packed Tower ◽  
Transfer Resistance ◽  
Steady State Model

Heat and mass transfer analysis between a desiccant-air contact system in a packed tower has been studied in application to air dehumidification employing liquid desiccant, namely calcium chloride. Ceramic 2 in. Raschig rings are used as the packing material. To predict the tower performance, a steady-state model which considers the heat and mass transfer resistances of the gas phase and the mass transfer resistance of the liquid phase is developed. The governing equations are solved on a digital computer to simulate the performance of the tower. The various parameters such as the effect of liquid concentration and temperature, air temperature and humidity and the rates of flow of air and liquid affecting the tower performance have been discussed.

scholarly journals Numerical Simulation of Gas-Particle Two-Phase Flow in a Nozzle with DG Method

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Duan Maochang ◽  
Yu Xijun ◽  
Chen Dawei ◽  
Qing Fang ◽  
Zou Shijun
Keyword(s):  
Flow Field ◽  
Gas Phase ◽  
Mass Fraction ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Governing Equations ◽  
Two Phase ◽  
Dg Method ◽  
The Impact

In this paper, the discontinuous Galerkin (DG) method is applied to solve the governing equations of the dispersed two-phase flow with the two-fluid Euler/Euler approach. The resulting governing equations are simple in form and the solution process is very natural. The characteristics of the gas-particle two-phase flow in an engine nozzle are mainly analyzed, and the impacts of the particle mass fraction and particle size on the flow field and engine performance are evaluated. Because of the addition of particles, the gas flow field undergoes significant modifications. Increase in the mass fraction leads to a significant thrust loss in the gas phase, and the impact of the particles on the gas phase could be substantial. Therefore, a quantitative study of thrust loss in the nozzle due to the particle impact is made. It is found that the gas thrust in the two-phase flow is reduced, but the total thrust of the two-phase flow increases to a certain extent.

300 MW Coal Tangential Boiler Furnace Numerical Simulation

2014 ◽  
Vol 597 ◽  
pp. 484-487
Author(s):  
Hong Xian Liu ◽  
Bin Xia Li
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Gas Phase ◽  
Governing Equations ◽  
Boiler Furnace ◽  
Temperature Deviation ◽  
Calculation Results ◽  
Simplec Algorithm ◽  
Flow Heat

By using the computational fluid dynamics software Fluent and the choice of the reasonable mathematical model, the flow, heat transfer and combustion are simulated in a 300 MW tangential firing boiler furnace. In the process of numerical simulation in the furnace, the gas phase turbulent flow usesRealizable model for both sides and solves the governing equations using SIMPLEC algorithm. Calculation results show that the highest temperature in the furnace is in the burner area,the whole furnace space rotates flow field, residual rotation still exists in the exit of the furnace, and the smoke temperature deviation causes in the residual rotation of furnace exit.

Solution of Governing Equations for Six-Field System Code

2017 ◽  
Author(s):  
Glenn A. Roth ◽  
George L. Mesina ◽  
Fatih Aydogan
Keyword(s):  
Gas Phase ◽  
Nuclear Power ◽  
Power Plants ◽  
Governing Equations ◽  
Field Equations ◽  
Two Phase Flows ◽  
Two Phase ◽  
Drift Flux ◽  
Continuous Fields ◽  
Analysis System

Modeling of two phase flows in nuclear power plants is very important for design, licensing, and operator training and therefore must be performed accurately. As requirements have increased, the form and accuracy of the models and computer codes have improved along with them. Early formulations for the field equations include: single phase liquid with algebraic drift flux for the gas phase, modeled with mass, momentum and energy governing equations; and two separate fields, liquid phase and gas phase, typically modeled with six governing equations. These lump bubbles and droplets into the gas and liquid phases respectively and use flow regime maps based upon available experimental data. However, the experiments do not cover the entire spectrum of reactor conditions, so that transitions and extrapolations, which are inherently inaccurate, must be employed. Further, some reactor scenarios, such as boiling and condensation, can be more accurately resolved by modeling bubbles or droplets separately from the continuous fields. Introduction of an additional field, droplet or bubble, apart from the continuous liquid and gas fields, generally uses nine governing equations. Despite the successful development of the above-mentioned methods for modeling reactor coolant flow in modern software, such as RELAP, TRAC, TRACE, CATHARE and many others, there remain reactor scenarios that require greater resolution to model. This is particularly true of conditions during reflood, where emergency spray flows dominate the cooling profile within the core. Existing system codes use a lumped approach for two phase flows that groups the fields by their phase, thereby losing track of the physical interactions between the discrete fluid fields. The accuracy of these accident analysis system codes can be improved by characterizing the interactions between additional coolant fields. To capture the effect of the various field interactions, governing equations involving six-fields have been developed. The six fields are 1) continuous liquid, 2) continuous vapor, 3) large droplets, 4) small droplets, 5) large bubbles and 6) small bubbles. The additional fields and the related governing equations introduce additional variables and source terms that require new closure relationships and primary variables. This article presents the equations and variables and develops the discrete set of 18 equations that must be solved to model the system.

Two-Fluid Model Simulation of Thermophoretic Deposition for Fine Particles in a Turbulent Boundary Layer

2007 ◽  
Author(s):  
Sh. Shahriari ◽  
H. Basirat Tabrizi
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Gas Phase ◽  
Fine Particles ◽  
Model Simulation ◽  
Fluid Model ◽  
Governing Equations ◽  
Diffusion Term ◽  
Two Fluid Model ◽  
Two Fluid

In this present paper, thermophoretic depositions of fine particles are used in a heated turbulent boundary layer over very small plate via two-fluid model, or Eulerian-Eulerian approach. The Prandtl’s mixing length model of turbulence is used for the closure problem. The governing equations of gas phase are coupled with the governing equations of particle phase in two-way model, while uses the particle diffusion term as another coupling term. The equations are solved numerically by using finite difference method. One can obtain the convergence by numerical calculations much easier than with no diffusion term. A vast amount of information can be extracted for this kind of modeling. The effect of important parameters such as diffusion factor, gravity and thermophoretic force are considered. The cooler temperature of plate results higher particles deposition or concentration on the flat plate. Also, the larger particle size diameters delay the maximum particles deposition further distance away from the plate front edge. The results give the correct physical prediction overall.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

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