Conduction Process HMT Tutorial- 4, Heat and Mass Transfer, Mechanical Engineering, GATE Video Lecture | Study Topper Handwritten Notes & Videos for GATE ME - Mechanical Engineering | Best Video for Mechanical Engineering

yes so in this video I am going to
discuss about conduction well as you
know this is one of the type of heat
transfer process right okay you can see
right now so what is happening in case
of conduction suppose that we are we are
having a rod right and this rod must be
if we wanted to transfer a theta this
rod must be good conductor of heat good
conductor of heat that is why heat can
transfer from one place coming from this
side to this side if temperature of this
side is Haeundae degree and this side is
20 degrees that means you know always
heat is always flow from higher
temperature to lower temperature
according to second law of
thermodynamics the same is here but why
this rod having more temperature in this
side then this side because we are
providing a sources of it suppose that
we are providing a sources of it that's
what now most important factor what is
and what is that let me share with you
in case of conduction heat is
transferring in K most of time most of
the time in solid okay now why it is
transferring from here to here because
of thermodynamics second law okay we
cannot talk on that when we cannot cause
something that okay that's truth so I am
NOT here to tell you all those things
what is going on in research I am here
to share with you what is conduction
basically so what is conduction that is
it is transferring from higher
temperature to lower temperature in case
of solid okay now now what why it is
happening that's because of only two
reasons
that's because of only two regions one
is free electrons free electrons and
another one is lattice vibration
vibration you know what is lattice
probably you have stereo physics solid
physics okay now because of free
electrons there is 70 percent heat
transfer is taking place and because of
lattice vibration there is 30 percent
heat transfer
is taking place okay so these two
factors that's why it is transferring in
solid okay no now why why I mean why it
is happening that's because of free
electrons most of the time okay now now
why why select or because of Phillip
dolls because in case of solid if solid
solid is good conductor good conductor
of heat and electricity good conductor
of heat and electricity that means that
solid is having abundant that means more
free electrons more flip tones and four
and as you know as I have already shared
with you there are two reasons because
of those reasons it is transferring from
in solid from higher temperature to
lower temperature one of the reason is
free electrons that is 70%
because in 70% is their chances is their
so that's because of free electrons is
present in good conductor of heat and
electricity all right so all metals are
good conductors of heat and electricity
as you know but if we see nonmetals if
you will see in one metals there two
things one is crystalline another one is
amorphous a more force right amorphous
material you know amorphous material are
very poor very poor thermal conductivity
that is key just like you know emotional
material glass you can say glass is the
amorphous material here thermal
conductivity is 1.25 what per meter
Kelvin but in case of crystalline just
like diamond diamond is having thermal
conductivity that is key as I think it's
more than even mm mm to work per meter
Kelvin and if you will see other metals
and will see metals metals in metals
maximum thermal conductivity
conductivity is having silver that is
around 400
word per meter Kelvin that means the
exceptional case is diamond and diamond
is not metal you know that so this like
graphite we have studied in electricity
what is the exception case which is
nonmetal and a good conducted a good
conductor of electricity that is
graphite here the same Goodkin nonmetal
but very very very good conductor of
heat that is diamond okay and when you
can see that come even compare silver
and diamond it's around five times more
okay now now what is most important
factor here here that is you know if you
see thermal conductivity thermal I mean
in my next lecture I will share with you
what is thermal conductivity exactly
that's why we can understand about it
thermal conductivity right thermal
conductivity is you noted while K okay
now now I have already shared with you
this unit is what per meter Kelvin here
right so in case of thermal conductivity
thermal conductivity based on these
based on these we can say how much the
material is having capability to heat
transfer
if anybody any metal is having any metal
or nonmetal having more thermal
conductivity that means that body is
having capability to task for heat much
more then if anybody is having less
thermal conductivity okay now think
about it okay now let us go for the
another concept of T's like suppose that
we are having a metal a metal a metal is
must be pure metal must be pure okay now
suppose that we are having another
another metal but that metal is alloy
okay if you'll see a pure metal thermal
conductivity and alloy thermal
conductivity then there is a you know
there is it yes that I must say there is
a very good concept here we are going to
learn you learn one of the best concept
here
if you
see these two metals I mean one is pure
metal another is a lie then what is
happening here
just let me share with you let's see the
pure metal is iron and alloy is steel
right now can you guess can you guess my
dear which metal is having or which
twisting is having much more thermal
conductivity even more thermal
conductivity then when which one is
having more thermal conductivity iron or
steel
can you guess about it yeah I am asking
you my dear
can you guess about it if he s then say
okay no problem let me share with you in
case of pure metal and alloy the pure
metal is having more thermal
conductivity than alloy this is proven
and as I have already shared with you
know there are they're basically diamond
why diamund is having a much more
thermal conducting that that's because
of this there is many reasons lucky like
but the that is one of the most biggest
reason is that diamond is a crystalline
and crystalline substance and you know
in case like here all those ladies are
closely packed there so that's why you
know that's why the task power of it has
transfer of it or feed is quite faster
than anything else okay and the diamond
is one more one more thing not only
crystallize this is a I know this is
what must say this is a perfectly
crystalline substance perfectly
crystalline substance that's why that
this is also one of the reason that you
know that diamond is having maximum
thermal conductivity like if if you see
another other other other metal must say
copper copper is having thermal
conductivity about 385 what per meter
Kelvin first second it will see other
metal gold oh wow that's really amazing
three one nine what per meter Kelvin
because of these and a gold is quite
good to conduct
electricity good conductor of
electricity conductor of electricity
that's why we used gold plate in mobile
phone that's why you know that is their
loss will be quite less that's why we
use coal plate in mobile phone and
that's this is also a good conductor or
field okay and because there are many
feel like tones present in this metal
now aluminium another good most of the
time most of the time we used aluminum
in case of transmission electricity
transmission lines probably you have
seen or maybe if you don't know as
someone we used aluminum wire to for
electricity transmission okay because
this is also having good this is a good
conductor of electricity as well as good
conductor of heat
now next steel that is why you know most
of our time most household people used
for top F what made of aluminum because
of quick cooking but that's not
recommended from me because that's not
healthier you cannot get healthier you
must use brass or something else now
steel steel is having also good
conductor of but that not up to the mark
about 45 what per meter Kelvin but here
if you see the least then I have already
shaved the silver silver is having
maximum thermal conductivity that is 400
watt per meter Kelvin so this is all
about conduction and in minutes lecture
it that would be that would be quite
short
I am share with you what is exactly
thermal conductivity and how what is
happening there and what is rate and
what we can do there and all those
things you will learn in that well
thanks for watching see you soon in my
next video bye