Simultaneous Heat and Mass Transfer Accompanied by Phase Change in Porous Insulation

1986 ◽  
Vol 108 (1) ◽  
pp. 132-140 ◽  
Author(s):  
K. Vafai ◽  
S. Whitaker
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat And Mass Transfer ◽  
Mass Transfer Process ◽  
Volume Averaging ◽  
Insulation Material ◽  
Insulation System ◽  
Two Phase ◽  
Local Volume Averaging ◽  
And Migration

This paper analyzes the accumulation and migration of moisture in an insulation material. The problem is modeled as a two-dimensional, transient, multiphase flow in a porous slab. The local volume-averaging technique is used to arrive at a rigorous and fundamental formulation of the heat and mass transfer process in an insulation system. The controlling parameters and assumptions are presented in detail. The equations are solved by devising a two-phase numerical scheme to obtain the condensation regions and the factors which affect the temperature distribution. The phase change process and its effects on the temperature, vapor density, moisture content, liquid content, and the vapor pressure distributions are discussed in detail. The significant transport mechanisms are identified and a simplified formulation of heat and mass transfer, accompanied by phase change, in an insulation system is presented.

Two-phase heat and mass transfer of phase change materials in thermal management systems

2016 ◽  
Vol 100 ◽  
pp. 215-223 ◽  
Author(s):  
Will Libeer ◽  
Francisco Ramos ◽  
Chad Newton ◽  
Morteza Alipanahrostami ◽  
Chris Depcik ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat And Mass Transfer ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Management Systems ◽  
Two Phase

Simulation of volumetric heating of a moist medium with allowance for fluid mobility

2012 ◽  
Vol 9 (1) ◽  
pp. 91-93
Author(s):  
U.R. Ilyasov ◽  
A.V. Dolgushev
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Numerical Solution ◽  
Heat And Mass Transfer ◽  
Transfer Process ◽  
Thermal Action ◽  
Mass Transfer Process ◽  
Low Permeability ◽  
Volumetric Heating ◽  
Drying Regime

The problem of volumetric thermal action on a moist porous medium is considered. Numerical solution, the influence of fluid mobility on the dynamics of the heat and mass transfer process is analyzed. It is established that fluid mobility leads to a softer drying regime. It is shown that in low-permeability media, the fluid can be assumed to be stationary.

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

A Study of GOTHIC 8.0 Code Application to AP1000 Containment Response

2013 ◽  
Author(s):  
Guodong Wang ◽  
Zhe Wang
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Mass Transfer Process ◽  
Transfer Model ◽  
Mass Transfer Model ◽  
Containment Model ◽  
Evaporation Heat ◽  
Containment Shell ◽  
Film Heat Transfer ◽  
Inside Wall

The AP1000 containment model has been developed by using WGOTHIC version 4.2 code. Condensation heat and mass transfer from the volumes to the containment shell, conduction through the shell, and evaporation from the shell to the riser were all calculated by using the special CLIMEs model. In this paper, the latest GOTHIC version 8.0 code is used to model both condensation and evaporation heat and mass transfer process. An improved heat and mass transfer model, the diffusion layer model (DLM), is adopted to model the condensation on the inside wall of containment. The Film heat transfer coefficient option is used to model the evaporation on the outside wall of containment. As a preliminary code consolidation effort, it is possible to use GOTHIC 8.0 code as a tool to analysis the AP1000 containment response.

Sign in / Sign up

Export Citation Format

Share Document