Boundary layer and heat transfer in a two-phase gas-evaporating droplet medium

1993 ◽  
Vol 27 (3) ◽  
pp. 331-337 ◽  
Author(s):  
E. V. Evstropova ◽  
A. N. Osiptsov ◽  
E. G. Shapiro
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Two Phase

scholarly journals Supercapillary Architecture‐Activated Two‐Phase Boundary Layer Structures for Highly Stable and Efficient Flow Boiling Heat Transfer

2019 ◽  
Vol 32 (2) ◽  
pp. 1905117 ◽  
Author(s):  
Wenming Li ◽  
Zuankai Wang ◽  
Fanghao Yang ◽  
Tamanna Alam ◽  
Mengnan Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Phase Boundary ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Two Phase ◽  
Layer Structures ◽  
Flow Boiling Heat Transfer

Heat Transfer From Vertical/Inclined Boundaries of Heat-Generating Boiling Pools

1982 ◽  
Vol 104 (3) ◽  
pp. 465-473 ◽  
Author(s):  
T. C. Chawla ◽  
S. H. Chan
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Expansion ◽  
Scaling Laws ◽  
Vapor Bubbles ◽  
Two Phase ◽  
Bulk Fluid ◽  
Upward Direction ◽  
Definition Of ◽  
Asymptotic Matching

A model for heat transfer from the sides of a volume heated boiling pool is proposed. Because of the density difference caused by volume boiling and by thermal expansion due to the temperature difference between the bulk fluid and the fluid near the wall, the lighter liquid and vapor bubbles cause movement of the bulk fluid in the upward direction. The rising liquid between the bubbles finds a return path along the walls or sides of the pool and forms a boundary layer which may be laminar in its initial length followed by transition to turbulent depending, of course, on the conditions prevailing at the entry to the sides and in the bulk of the pool. The analysis for the laminar case provides the definition of equivalent Grashof number for the combined two-phase and thermal expansion driven natural convection along the sides of pool. The turbulent boundary layer is analyzed by assuming a two-layer model in which the inner layer is characterized by viscous and conduction terms and the outer by mean convection terms. The similarity analysis of the governing equations yields universal profiles for temperature and velocity and the scaling laws for the inner and outer layers. An asymptotic matching of the temperature profile in the overlap region leads to a heat transfer law which correlates the available experimental data on volume heated boiling pools exceedingly well.

Magnetic bubbles dynamics and heat transfer characteristics under influence of non-uniform magnetic fields

2021 ◽  
pp. 095440622110358
Author(s):  
MM Larimi ◽  
A Ramiar ◽  
H Ramyar ◽  
Hamid Kazemi Moghadam
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
External Magnetic Field ◽  
Flow Field ◽  
Thermal Boundary Layer ◽  
Computational Study ◽  
Two Phase ◽  
Navier Stokes Equation ◽  
Vof Model

The computational study of transient immiscible and incompressible two-phase flows is one of the most common and desirable way for investigation of engineering phenomena and physics science. In the previous studies, generally bubbles current have been used as an active method for increasing heat transfer, however, due to existence of hydraulic boundary layers, the bubbles were not able to cross over this layer to thinning the thermal boundary layer and consequently the efficiency of this method was not very considerable. In this study, by considering potential of magnetic field, the effect of co-applying of external non uniform magnetic field and magnetic bubbles in enhancing the heat transfer efficiency in a 3-D tube has been investigated. The computational model consisted of the Navier–Stokes equation for liquid phase and VOF model for interface tracking are carried out by OpenFOAM. The external magnetic field has been considered non-uniform and time dependent. The results predicted that magnetic bubbles and external magnetic field due to their effect on thermal boundary layer increased significantly heat transfer and Nusselt number. Furthermore, results indicated magnetic bubbles can act as an active torbulators in the flow field and can be applied for increasing recirculation and secondary flow in the flow field. The average temperature and magnetic field over times for different cases have been discussed in the results.

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