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Heat and Mass Transfer

, Volume 43, Issue 11, pp 1201–1211 | Cite as

Flows in a lower half heated upper half cooled cylindrical model reactor loaded with porous media

Original

Abstract

This paper presents an experimental and numerical investigation on the natural convection flow in a cylindrical model hydrothermal reactor. The flow is visualized non-intrusively and simulated with a conjugate computational model. Results show that the flow structure consists of wall layers and core flows. In the lower half, the flows are steady due to the porous media. The three-dimensional unsteady upper core flow is driven by the streams originated from the wall layer collision. The thermal condition in the upper half core region is mainly determined by the total heat flow rate specified on the lower sidewall; while the variations of porous media parameters, in the normal range for hydrothermal crystal growth process, have minor effects.

Keywords

Flow Structure Lower Half Thermal Environment Wall Layer Flow Image 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

C1, C2

coefficients in the porous media model

Cp

heat capacity

Db

diameter of the balls in the porous region

Di

inner diameter of the reactor, 50 mm

\({\overrightarrow{F}} \)

buoyancy force

\(\ifmmode\expandafter\vec\else\expandafter\vecabove\fi{g}\)

gravity vector

gx

gravity component in x-direction

gz

gravity component in z-direction

H

height of the reactor, 305 mm

keff

effective conductivity in the porous region

kf

conductivity of the fluid

ks

conductivity of the solid

kw

conductivity of the reactor glass wall

P

pressure

Pr

Prandtl number

Q

total heat flow rate on lower half wall

\(\hbox{Ra}_{{D_{\rm i}}}\)

Rayleigh number based on D i

S

source term in the momentum equation of the porous media model

T

temperature

T0

reference temperature

Tinf

air temperature in the surrounding environment, 24.3°C

\(\overline{{T_{\rm c}^{\rm u}}} \)

time averaged temperature at the center of the upper half

t

time

Tu

temperature at the center of the upper half

Tu0

temperature at the center of the upper half when Q = Q 0

\(\ifmmode\expandafter\vec\else\expandafter\vecabove\fi{U}\)

velocity vector

wu

z-velocity at the center of the upper half

wu0

z-velocity at the center of the upper half when Q = Q 0

xyz

coordinates

xp

coordinates in pixel in the corrected images

xp

coordinates in pixel in the raw images

Greeks

β

thermal expansion coefficient of the fluid

ρ

fluid density

θ

angle between gravity and z-axis of the reactor

ϕ

porosity in the porous region

μ

molecular viscosity

ν

ν = μ/ρ

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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringThe University of AkronAkronUSA

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