WEBVTT
Kind: captions
Language: en
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.
So, welcome back now we come to the end of
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this course ok and I thoroughly enjoyed
this course I hope that you might have also
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enjoyed the course if you have any problem.
Please let us know let we will try to solve
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your issues and you try your problem, I would
know quickly want to revise the course or
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I will summarize the course that; what is
the main base? An aim of the course, what
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we have tried to do and you may have got benefited
with some of this content .
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So, what we initially did? The main motive
of the course was as I said that multiphase
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flow reactors a heart of any chemical process
industries. So, if you go for any process
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ok you go for any industry, petroleum industry,
pharmaceutical industry, food industry, treatment
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places to go for bulk chemical industries.
You go for fine chemical industries you go
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for power plants any places any chemical related
industries you go for mining you go for steel
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processing you will see that every where there
is a multiphase flow which is taking place
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ok. And the multiphase flow is generally the
heart of that industry you will see that whatever
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the reactor or the processes they are using
the most critical processes actually the multiphase
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flow process .
And we said that the multiphase flow process
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this is very ongoing research topic very hot
topic of the research and why it is still
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ongoing topic and very hot topic of research
is that; the phenomenon governing in the multiphase
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flow depends on different parameters and that
most critical parameter is that it depends
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on what type of fluids you are handling? Whether
the; you are using gas solid whether you are
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using liquid solid whether you are using gas
liquid whether you are looking liquid liquid
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and all .
So, it depends on that type of the liquid
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it depends on the column geometry whether
you are operating a vertical column; whether
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you are operating a horizontal column it depends
on column dimensions,, whether you are operating
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a 1 inch column 2 inch column 1 meter column
5 metre column which depends on the column
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inclination also whether you are using a say
vertical or horizontal whether if the column
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is inclined at 45 degree or. So, .
So, there are lot of parameter is depends
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on ok and; that is the reason that the design
and scale up of these prob[lem]- or this kind
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of a processes is still a challenge and most
of the time it depends on the art rather than
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the science . So, what we have tried to do
in this course? We have tried to remove the
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art part of it that we come over the empirical
correlation we try to see, that how to do
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the basic force balance? Basic material balance
basic rewrite the transport equations in such
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a way that we can understand the dynamics
of the bed . So, we what we did we first started
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with the basic introduction of the course
we introduce the different terminology ok
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.
I can introduce that what is the void fraction
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number density, what is autocorrelation function?
What is the mixture density and also we started
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with very basic definitions of the multiphase
flow. We tried to understand different kind
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of flow pattern which take place. Now, once
we are going with the flow patterns; which
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is very very critical, because again the behaviour
of the bed depends on that; what regime you
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are operating ? So, say for the gas liquid
whether you are operating in the bubbly regime
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whether you are operating the slug flow regime
churn turbulent regime and all. So, so on
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each kind of each interaction have different
regimes and your bed behaviour is largely
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depends on that what regimes you are operating
.
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So, we have tried to discuss the regimes of
operation for the gas liquid for the liquid
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solid for the gas solid and for the liquid
liquid both . So, all these things we have
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try to understand the different regimes we
have tried to see that; why? How this regimes
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are dependent on the column geometry it means
the column inclination and column dimensions.
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So, that makes the life for the complicated
that these regimes are dependent on the column
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geometry inclination and as well as the
column dimensions ok and the fluid type if
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you change the fluid type the; your regimes
will change .
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So, we have tried to classify the regimes
we have try to understand that for different
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processes, what type of regimes you should
operate? What is the advantage of each regime?
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What is the disadvantage of each regime? What
is the typical characteristic of each regime?
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Then, we started with the your first principle
equations, we started with the basic force
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balance, we have tried to do the basic force
balance, we have tried to drive the Reynolds
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transport theorem from Reynolds transport
theorem. We derive the Navier-Stokes equation
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or momentum equation and then from both the
momentum equation. We have simplified it for
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the one dimensional domain . So, that we can
easily understand, the dynamics removing the
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critical part of the mathematics so that we
can focus more on the force balance centre
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.
So, we have done that single dimensional equation,
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we have written for again, we started with
the gas liquid, we have done it for the separated
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flow, we have done it for the homogenous flow,
we have done it for the bubbly flow, and we
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have done it for the annular flow. We have
written the basic equation mathematical equation
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starting from the first principle of the force
balance or momentum balance we have developed
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the equation for the pressure drop of all
this condition . So, that you can see that
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how the different regime pressure drops will
be different .
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We have also discussed some of the empirical
correlations like Lockhart Martinelli equation
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which may not be very accurate, but gives
a very good idea about the pressure drop in
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a very short time . So, we have tried to blend
it both the first principle as well as the
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empirical equations together to understand
the hard core knowledge or to understand the
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physics of the multiphase flow and also to
keep the calculation handy ok. So, that we
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can easily calculate it is not like you need
to wait for 1 month for 10 days or 20 days
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to get the first hand calculations . So, that
is why we discuss the in blend of both we
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blended it the first principle as well as
the empirical correlations together .
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We have again developed the particle tracking
equation for the single particles we have
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keep on increasing the flow that forces
we complicate the problem. We first initially
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that only particle is falling down, then we
are saying the particle is moving horizontal.
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First, we started actually with the horizontal
were only drag was there then we said that
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the particle is moving downward it will settling
down drag and gravity was taking a place,
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then we introduced buoyancy forces. Then we
introduce the any other forces like the electro
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forces forces electrical forces; that if it
is there how the particle motions will be
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there and we try to see that how the particle
tracking can we take place in the Lagrangian
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tracking domain .
Then once we have done for the one d models
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what we have done we have started moving to
the more complicated mathematical model which
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is kind of a current state of the art. So,
once you understood the one dimensional model
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the; now we tried to introduce the basic part
of the mathematics also to see that; how we
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can do it in the three dimensional domain?
So, we introduce the different models which
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is being critically used in the industry or
in academe to understand this kind of reactor
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behaviour we started with the Lagrangian track
which we have already discussed then algebra
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slip model. We discuss about the model equations
the major assumption for which the model has
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been developed and the limitation of each
model. So, we discussed the algebraic slip
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we discussed the Euiler Euiler we discussed
the Euiler Lagrangian model for both gas liquid
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gas solid and liquid solid all three this
phases we have discussed and simply it is
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also applicable to the liquid liquid .
So, we discussed the different mathematical
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model which is being there we discuss the
advantage and disadvantage of each model limitation
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of each model capabilities of each model,
what you can expect from the model results
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ok where you cannot use where you can use
and all. So, all those things we have tried
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to discuss and then we found that all these
models are still not kind of; you can say
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the matured enough that you can surely depend
on the model predictions particularly for
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the multiphase flow. And therefore, you need
a experimental validation you need experiment
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input to see that, and why it is the state?
Because, several these models use several
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empirical developed correlations and we do
not know whether those empirically developed
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correlations are correct .
So, to understand that we discussed the different
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forces which is being used in this model like,
drag force, left force, virtual mass force,
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history forces all those forces we have tried
to see and we have discuss the different correlations
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available for these forces which mean some
of these correlations are developed empirically
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were with like some other drag; we have discussed
about the Gledart force Shyam Lal say Sciller
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Neumann in the gas liquid flow mostly Alexander
for the gas liquids. So, we have the spectrum
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of the drag forces we have seen that how this
drag forces are being developed empirically
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develop actually.
And once you are using these developed drag
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forces in a numerical model definitely a production
of the numerical model is going to depend
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on the, what is the accuracy of your drag
model? And to understand; whether your drag
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model is valid there or not, you have to have
the experimental validation. Drag is a very
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simple example, that is why I am giving, but
there are several other correlations also
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which we have used like for the gas solid
we have used the solid as a continuous say
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in the Euler Euler we have developed several
empirical correlations like for the solid
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viscosity Lunet et al., and all. So, bulk
viscosity this will this all those things
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we have discussed developed and those things
you need a serious experimental validations
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.
So, we discuss all those parameters then we
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also discuss about the drag that how the single
particle and multi particle drag will change
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and how the correlation comes into the picture
how the drag can be written in form of the
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beta of k m f like different books for
this different correlations ok .
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And, then we move towards the experimental
validation that how you can do the experimental
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validation, what are the different techniques
available current date as of? Now, we developed
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some briefly on this part ok and
we try to understand the limitation and advantage
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of each technique it means capabilities of
each technique, what again similar way? What
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you can expect from this technique? What is
will be the accuracy whether it can be used
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for the validation or not.
And there after we started with the different
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type of reactor . So, initially what we have
done we have discussed about the bubble column
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reactor. We have discussed again that;
what is the bubble column reactor? What is
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the application of this? How the hydrodynamics
in the bubble column depends? How to calculate
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the bubble diameter? How to calculate the
bubble velocity? How this coalescence will
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change the bubble behaviour? What is the different
type of the bubble column reactor available?
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What is the advantage and disadvantage of
each reactor? And, we will again use the basic
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principle to calculate the first principle;
whatever the way we have developed the single
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dimensional equation, we did the force balance
we tried develop the equation for the bubble
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velocity we developed the equation for the
bubble diameter calculation all. So, all those
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things we have done and we have tried to develop
that do the basic force balance. So, that
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you can in a reactor you can do that force
balance whatever we have done .
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Then they move to the gas solid reactor we
discuss the first the packed bed reactor.
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Again, we discuss the advantage of the packed
bed reactor then from the basic first principle
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again. We did the force balance with see that
how the force balance take place in the packed
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bed reactor for different velocity, low velocity
and higher velocity we have discussed about
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the pressure drop how it will change. So,
we have discussed the Kozeny-Carman equation
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. So, we discussed the Burke-Plummer equation
and then the combination of that is actually
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called Ergun question . So, we discuss about
the Ergun equation that, how it is been derived?
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how this the particle shape take a role
in that a play a role in that we discuss all
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those things and then finally, the move towards
the gas solid fluidized bed reactor or say
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fluidized bed reactor.
We discuss the advantage of the fluidized
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bed reactor what packed bed like better heat
and mass transfer coefficient. We discuss
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that how critical it is to operator a fluidized
bed and how the hydrodynamics places a such
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a critical role, as while discussing we said
that the hydro dynamics of the bubble fluidized
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bed. Actually depends on many parameters like
column inclination, column angle, column geometry,
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whether it is a vertical or conical then this
gas velocity or the fluid velocity I will
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say .
What is the particle size? What is a particle
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density means? The Geldart classification
of the particle. What group of the geldart
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particle you are using? What is your particle
size distribution; whether you want to operate
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a circulating bed or you want to operate a
batch reactor bad or mean say I will say that
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from the till the turbulent bed .
So, all those things changed your dynamics
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and what we have try to understand that to,
how to analyze the system? What is the critical
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parameter once you do that system and how
to calculate the minimum fluidization velocity
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?
So, inherently in this course the idea was
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to expose you with the different kind of a
multiphase flow reactors the problem which
00:12:46.310 --> 00:12:50.650
you phase in different type of multiphase
flow reactors. How the basic principles can
00:12:50.650 --> 00:12:55.250
be used? The basic force balance or maybe
say momentum balance can be used to analyze
00:12:55.250 --> 00:13:00.630
those kind of a problem. What you should look
for in this reactors? What are the critical
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things which you should analyze while designing
this reactors and all .
00:13:04.620 --> 00:13:09.350
So, this was the whole idea to introduce you
about the multiphase flow different reactors
00:13:09.350 --> 00:13:15.250
used in the multiphase flow and to give you
idea that how critical they are and how by
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using the very basic first principle you can
analyze this system. I hope this course will
00:13:21.430 --> 00:13:26.420
be enjoying for you you must have enjoyed
this course I just hope this and if any problem
00:13:26.420 --> 00:13:46.650
is there please feel free to contact us. With
this I rest this course and.
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Thanks a lot .