Heat and mass transfer in heat pipes with noncondensing gas

1973 ◽  
Vol 25 (2) ◽  
pp. 988-992
Author(s):  
L. L. Vasil'ev ◽  
S. V. Konev
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heat Pipes

scholarly journals Heat and Mass Transfer in the Vicinity of the Vapor-Gas Front in a Gas-Loaded Heat Pipe

1972 ◽  
Vol 94 (2) ◽  
pp. 155-162 ◽  
Author(s):  
D. K. Edwards ◽  
B. D. Marcus
Keyword(s):  
Mass Transfer ◽  
Heat Pipe ◽  
Heat And Mass Transfer ◽  
Heat Pipes ◽  
Mass Diffusion ◽  
Working Fluid ◽  
Predictive Capability ◽  
Axial Mass ◽  
Axial Heat ◽  
And Control

An analysis is presented of axially conducting gas-controlled heat pipes leading to a predictive capability for the heat and mass transfer along the heat pipe. In addition, experimental results are presented which verify the analysis, and computational results are presented which show the relative influence of various parameters which affect the system behavior. In particular it was found that axial heat conduction is of much greater importance than axial mass diffusion in establishing the wall temperature profiles and condenser heat-transfer characteristics of gas-loaded heat pipes. However, mass diffusion and, consequently, the choice of working fluid and control gas are of considerable importance in establishing the “diffusion freezeout rate” if the potential exists for freezing of vapor which penetrates the gas-blocked portion of the condenser. It is believed that the analysis and associated computer program are useful tools for designing gas-loaded heat pipes.

scholarly journals Influence of Turbulence, Density, Phase Change, and Phase Interfaces Models on the Performance of the Numerical Simulation of a Two-Phase Closed Thermosyphon

TecnoLógicas ◽  
2020 ◽  
Vol 23 (49) ◽  
pp. 53-70
Author(s):  
David Gamboa ◽  
Bernardo Herrera
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat And Mass Transfer ◽  
Saturation Temperature ◽  
Heat Pipes ◽  
Nucleate Boiling ◽  
High Energy ◽  
High Mass ◽  
Detailed Knowledge ◽  
Good Representation

A heat pipe can be considered a highly effective thermal conduction device, which is especially desirable in heat transfer operations in order to ensure high energy efficiency. However, the operation of heat pipes comprises different heat and mass transfer phenomena, such phase change, heat conduction and convection, solid-liquid and vapor-liquid surface interactions, surface vaporization, and nucleate boiling. Therefore, modelling heat pipes is a highly complex task that demands detailed knowledge of the physical phenomena involved and choosing suitable theoretical models to obtain a good representation of the real nature of the heat and mass transfer processes. In this study, some models and parameters available in the commercial CFD software ANSYS Fluent for turbulence, density, phase change, and phase interfaces were examined to determine their influence on the prediction of the heat and mass transfer in a two-phased closed thermosyphon (TPCT). The numerical results show that using a turbulence viscous model is not necessary and that a variable density model improves the temperature distribution inside the TPCT. Furthermore, using high mass and energy transfer coefficients during condensation makes the vapor remain close to the saturation temperature. Finally, a sharp interphase model is strongly recommended for this type of process.

Heat and Mass Transfer for a Constant Heat Boundary in Porous Reactive Medium under Local Non Equilibrium Conditions

2010 ◽  
Vol 297-301 ◽  
pp. 181-186
Author(s):  
A. Bousri ◽  
K. Bouhadef ◽  
Hassen Beji ◽  
Omar Rahli
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Exothermic Reaction ◽  
Heat Pipes ◽  
Catalytic Reactors ◽  
Equilibrium Conditions ◽  
Reactive Medium ◽  
Exothermic Chemical Reaction ◽  
Volume Method

A two dimensional mathematical model has been developed to simulate the coupled heat and mass transfer in a porous medium undergoing a strong exothermic reaction. The problem has received a lot of interest due to its relevance in a wide variety of engineering applications such heat pipes, nuclear reactors, drying technologies, catalytic reactors and others. The fluid flow is modelled via the Darcy-Brinkman-Forchheimer equation. This model is solved numerically by the finite volume method, and the code is validated by comparing with previously published works. The influence of the exothermic chemical reaction on the heat and mass transfer in the porous medium is discussed. The effects of pertinent parameters such as the Biot number, the Reynolds number and the Frank-Kamenetskii number were analyzed. Quantitative and qualitative results are presented. Comparisons with other works in the literature are performed and excellent agreement between the results is obtained.

scholarly journals Mathematical Modeling of Heat and Mass Transfer in Heat Pipes in a One-Dimensional Formulation when Cooling Active Phased Antenna Arrays

2021 ◽  
Vol 15 ◽  
pp. 196-203
Author(s):  
S. Radaev
Keyword(s):  
Mass Transfer ◽  
Heat Pipe ◽  
Heat And Mass Transfer ◽  
Antenna Arrays ◽  
Saturation Temperature ◽  
Heat Pipes ◽  
Equilibrium Temperature ◽  
One Dimensional ◽  
Phased Antenna Arrays ◽  
The Mathematical Model

The work proposes test one-dimensional models of heat and mass transfer in heat pipes during cooling of active phased antenna arrays, which can be used in processing the test results of flat heat pipes in order to determine their performance characteristics and identify the parameters required for modeling in a more complex setting (for example, in flat and taking into account the presence of several localized sources of heat supply). To take into account the influence of the heat release power on the equilibrium temperature inside the heat pipe, the model has been added to take into account the dependence of the steam saturation temperature on the pressure, which is realized inside the steam pipeline when the heat pipe is heated. Numerous calculations carried out made it possible to refine the mathematical model. In particular, a significant effect on the temperature distribution along the heat pipe is shown, taking into account the dependence of the steam saturation temperature on the pressure in the parawire. It is shown that the introduction of standard functions for the characteristics of the coolant (water) in the liquid and vapor state, as well as taking into account the capillary pressure on temperature, makes it possible to refine the resulting solution.

Macroscale and Microscale Phenomena Encountered in Multiphase Energy Storage and Transport System

2010 ◽  
Author(s):  
Masahiro Kawaji
Keyword(s):  
Mass Transfer ◽  
Energy Storage ◽  
Heat And Mass Transfer ◽  
Phase Change Materials ◽  
Energy Transport ◽  
Ostwald Ripening ◽  
Heat Pipes ◽  
Heat Fluxes ◽  
Transport Systems ◽  
Enhancement Effect

Complex macroscale and microscale heat and mass transfer phenomena encountered in several thermal energy storage and transport systems are discussed. Thermal storage and transport systems involving ice slurries and nanoemulsions of phase change materials can be used for either cooling or heating applications or both, which can contribute to the reduced usage of electricity during peak hours. But heat and mass transfer and stability issues are encountered in the production, transport and storage of the heat storage media. Both the heat transfer enhancement effect and detrimental effects such as Ostwald ripening and supercooling will be discussed. Another interesting microscale phenomenon recently encountered in energy transport devices such as heat pipes is the enhancement of heat transport with the use of self-rewetting fluids. Critical heat fluxes in boiling can be enhanced by up to 300% and this helps prevent liquid dryout at high heat fluxes in different types of heat pipes. Both the nature of the enhancement effect and possible mechanisms will be discussed.

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