Heat and mass transfer during growth of a spherical particle from the liquid phase

1979 ◽  
Vol 37 (6) ◽  
pp. 1389-1393
Author(s):  
A. N. Verigin ◽  
I. A. Shchuplyak ◽  
M. F. Mikhalev ◽  
V. V. Varentsov
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Spherical Particle ◽  
Heat And Mass Transfer

Thermal convection in melting zone of hollow microparticle Al2O3

2021 ◽  
pp. 20-25
Author(s):  
V.V. Shekhovtsov ◽  
◽  
YU.A. Abzaev ◽  
O.G. Volokitin ◽  
A.A. Klopotov ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Numerical Modeling ◽  
Liquid Phase ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Thermal Convection ◽  
Melting Zone ◽  
Melting Front ◽  
Α Al2o3 ◽  
Inner Region

The paper presents the results of numerical modeling of development melting zone hollow spherical microparticle α-Al2O3. The object of the study was part circular sector, which represents the shell of hollow particle, which is formed under action plasma flow. Numerically describe the unsteady convective heat and mass transfer in shell hollow particle, we used the system Navier-Stokes equations in Boussinesq approximation, which describes the weak convection medium. Due to the high coefficient of porosity (P = 0.56) initial agglomerated particle with the α-Al2O3 structure, the inner region at the stage of heating Tp ≥ Tmelt is in the conditions heat exchange with the incoming heat flux, as result of which the temperature center coincided with the temperature particle surface. Result of overheating of the condensed phase, liquid layer of fused grains is formed in the inner and outer regions microparticle. In this case, the melting front is directed towards center shell. Result of numerical modeling, it has been established that convective heat and mass transfer is observed in melting zones (liquid phase), vector field of which covers almost the entire region of the liquid phase. It was found that thermal convection in the external liquid phase is characterized by velocities that are more than 2 times higher than the displacement velocity in the inner region of the particle. It is shown that there is no displacement of the material inside the convection region, thereby inhomogeneous heating occurs in the molten layer of the particle, which significantly affects the speed of movement of the melting front.

scholarly journals Numerical Modelling of Tailings Dam Thermal-Seepage Regime Considering Phase Transitions

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Aniskin Nikolay Alekseevich ◽  
Antonov Anton Sergeevich
Keyword(s):  
Phase Transition ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Heat And Mass Transfer ◽  
Variational Formulation ◽  
Tailings Dam ◽  
Real Situation ◽  
Dam Foundation ◽  
Liquid Phase Transition ◽  
Calculation Results

Statement of the Problem. The article describes the problem of combined thermal-seepage regime for earth dams and those operated in the permafrost conditions. This problem can be solved using the finite elements method based on the local variational formulation. Results. A thermal-seepage regime numerical model has been developed for the “dam-foundation” system in terms of the tailings dam. The effect of heat-and-mass transfer and liquid phase transition in soil interstices on the dam state is estimated. The study with subsequent consideration of these factors has been undertaken. Conclusions. The results of studying the temperature-filtration conditions of the structure based on the factors of heat-and-mass transfer and liquid phase transition have shown that the calculation results comply with the field data. Ignoring these factors or one of them distorts the real situation of the dam thermal-seepage conditions.

HEAT AND MASS TRANSFER ON POROUS MEDIUM SURFACE WITH VAPOR-LIQUID PHASE CHANGE

2018 ◽  
Author(s):  
Shixue Wang ◽  
Minghui Ge ◽  
Yulong Zhao ◽  
Fei Wang ◽  
Bin Dong
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Liquid Phase ◽  
Phase Change ◽  
Heat And Mass Transfer ◽  
Vapor Liquid

A Mathematical Model of Condensation Heat and Mass Transfer to a Moving Droplet in its Own Vapor

1984 ◽  
Vol 106 (2) ◽  
pp. 417-424 ◽  
Author(s):  
J. N. Chung ◽  
Tae-Ho Chang
Keyword(s):  
Boundary Layer ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Heat And Mass Transfer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Droplet Radius ◽  
Integral Approach ◽  
Boundary Layer Equations

A mathematical model appropriate for predicting condensation heat and mass transfer rates along the surface of a droplet moving in pure vapor is developed. A Karman-Pohlhansen type of integral approach was adopted for the solution of vapor-phase boundary layer equations. The diffusion-dominated internal core was solved using a finite difference numerical scheme. The rate-controlling mechanism of pure vapor condensing on a droplet was found in the thermal core region of the liquid phase where the streamlines correspond to the isotherms and diffusion is the primary transport mechanism. The total rate of heat transfer is found to be inversely proportional to the droplet radius. The condensation velocity at the vapor-liquid interface reduces the boundary layer thickness and moves the separation point toward the rear stagnation point. The internal motion also helps increase the transport rates by reducing both the boundary layer thickness and thermal resistance in the liquid phase. The results predicted by this model compare favorably with available experimental values.

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