bhagat.pdf final2
Post on 10-Apr-2018
223 Views
Preview:
TRANSCRIPT
-
8/8/2019 BHAGAT.pdf Final2
1/24
Studies in bubble formation-IV : Bubble formation at porous discs
B. Bowonder and R. Kumar
Rajesh Kumar Bhagat
-
8/8/2019 BHAGAT.pdf Final2
2/24
Overview
Introduction Mathematical model
Results summary Conclusions
Indian Institute of Science 2010
-
8/8/2019 BHAGAT.pdf Final2
3/24
Objective and motivation
To study the bubble formation from porous disk and predict a model which can explain the physics of problem from first principle.
There was no paper to explain the effect of
surface tension and viscosity, so address that problem.
Indian Institute of Science 2010
-
8/8/2019 BHAGAT.pdf Final2
4/24
phenomena of bubbleformation
Indian Institute of Science 2010
First stage is expansion stage.
Second stage is detachment stage.
. ., - -A Ohnuki et al Development of Multidimensional
Two Fluid Model Code ACE 3D for,Evaluation of Constitutive Equations J - / -JAERI Data Code 96 033 ( ).1996
http://jolisf.tokai.jaeri.go.jp/pdf/dat/JAERI-Data-Code-96-033.pdfhttp://jolisf.tokai.jaeri.go.jp/pdf/dat/JAERI-Data-Code-96-033.pdfhttp://jolisf.tokai.jaeri.go.jp/pdf/dat/JAERI-Data-Code-96-033.pdf -
8/8/2019 BHAGAT.pdf Final2
5/24
Indian Institute of Science 2010
Mathematical model for the process
Force balance on bubble
Expansionstage
Detachment stage Condition for Detachment
= nertial force buoyancy force viscous force orce due to surface tension
-
8/8/2019 BHAGAT.pdf Final2
6/24
Assumptions for the model
Indian Institute of Science 2010
Porous disc is made of large number of pores of uniformdiameter and length having same resistance. Number of operative sites is equal to number of bubblesimultaneously on the disk which is only a fraction of totalnumber of sites.
Effective pores may be made of number of pores but in thisanalysis single pore is considered and flow through a single pore is considered.Bubble arrange themselves in hexagonal close packedmanner.
Flow
rate
increase
f fe ct iv e s it es
-
8/8/2019 BHAGAT.pdf Final2
7/24
Mathematical model
Indian Institute of Science 2010
Number of bubble by considering hexagonal close packing
Hexagonal close packing ofbubble
( )1
( )2
-
8/8/2019 BHAGAT.pdf Final2
8/24 Indian Institute of Science 2010
Mathematical model for expansion stage
( )3
-
8/8/2019 BHAGAT.pdf Final2
9/24 Indian Institute of Science 2010
Mathematical model for detachment stage
( )IV
-
8/8/2019 BHAGAT.pdf Final2
10/24 Indian Institute of Science 2010
Verification of model
Experimental setup
-
8/8/2019 BHAGAT.pdf Final2
11/24 Indian Institute of Science 2010
Range of variable covered during investigation
variable rangeviscosity 1- 604cP
Surface tension 22.8-71.8 dyn/CmDensity 0.792-1.255 g/Cm3Flow rate of air 10-220 Cm3/secPore diameter 45-110
Superficial velocity 4.389-60.94Cm/sec
-
8/8/2019 BHAGAT.pdf Final2
12/24 Indian Institute of Science 2010
Results and discussion
,
Bubble
volume
Cm
3
,low per site Cm 3 / sec
Effect of surface tension, viscosity and pore diameter
-
8/8/2019 BHAGAT.pdf Final2
13/24 Indian Institute of Science 2010
Results and discussionEffect of surface tension,viscosity and pore diameter
,
Bubble
volume
Cm
3
,low rate per si te Cm 3 / sec
-
8/8/2019 BHAGAT.pdf Final2
14/24 Indian Institute of Science 2010
Results and discussion
Theoretical
bubble
volume
Cm
3
ubble volume experimental Cm 3
omparison between bubble volume
-
8/8/2019 BHAGAT.pdf Final2
15/24
Indian Institute of Science 2010
Results and discussion
Number
o
f
sites
calc
ulated
umber of sites experimental
Comparison of number of sites
-
8/8/2019 BHAGAT.pdf Final2
16/24
Indian Institute of Science 2010
Conclusions
With increase in pore diameter, surface tension, andviscosity, bubble volume is increasing at low flowRate, but after a certain flow rate these factors are notIncreasing the bubble volume.
With this model, there was possibility for the explanationof bubbles in fluidized bed and author was working in that area.
-
8/8/2019 BHAGAT.pdf Final2
17/24
Thank you
-
8/8/2019 BHAGAT.pdf Final2
18/24
Indian Institute of Science 2010
Results and discussion
-
8/8/2019 BHAGAT.pdf Final2
19/24
Indian Institute of Science 2010
odel for expansion stage
-
8/8/2019 BHAGAT.pdf Final2
20/24
Indian Institute of Science 2010
odel for expansion stage
-
8/8/2019 BHAGAT.pdf Final2
21/24
Indian Institute of Science 2010
odel for detachment stage
-
8/8/2019 BHAGAT.pdf Final2
22/24
Indian Institute of Science 2010
odel for detachment stage
-
8/8/2019 BHAGAT.pdf Final2
23/24
Indian Institute of Science 2010
-
8/8/2019 BHAGAT.pdf Final2
24/24
Indian Institute of
top related