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GUIDED BY-
B.J. SONANI SIR
PREPARED BY:-
MAYANK H. PAL
5TH SEM MECH.ENGG.
(136120319528)
Topic-:Thermo electric
coolingSub-:Project-1
Gadhiya Sagar K. (136120319506)
Marakana Sanket S. (136120319521)
Mendapara Prince K. (136120319523)
Modi Anuj B. (136120319525)
Pal Mayank H. (136120319528)
Parmar Maulik R. (136120319530)
The thermoelectric cooling is used as renewed
technology, has made an impact in the field of
alternative refrigeration. The common principle
is the presence of coupled electrical and
thermal currents, so that it is possible to use the
effects to generate power from a temperature
differential.
Thermoelectric cooling provides an alternative
solution to the common compressor and
absorber cooler. Thermoelectric coolers are
used especially if small cooling power is
needed (up to 500 W)
Thomas Seebeck in the early 1820’s found that
a voltage difference is generated between the
hot and cold ends when certain materials are
placed in a temperature gradient.
This phenomenon is popularly known as
Seebeck effect.
Depending on the used heat exchangers the
cooling units are distinguished:
air to air
air to fluid
fluid to fluid
direct to air (cooling plate to air)
small size
light in weight
no fluid
independent from the working position
high reliability
exact temperature control
heating by changing the direction of the current
The basic principle behind thermoelectric effect is peltier effect it occurs whenever electric current flows between two dissimilar conductors, depending on the direction of the current flow, the junction of the two conductors will either absorb or release heat.
A thermoelectric material is made of two legs, one of which is ‘n-type’ and contains negatively charged mobile carriers in the form of electrons while the other leg is ‘p-type’ and contains positively charged mobile carriers known as holes. These two legs are connected electrically in series and thermally in parallel.
By connecting 2 wires of different electrically
leading materials at the 2 ends and by applying
additionally a voltage, a current flows, which
transports heat of one junction point to the other.
In the consequence one junction point becomes
cold and the other one warm.
For thermoelectric modules materials are applicable
with a high electrical conductivity and a small thermal
conductivity. Unfortunately good electrical conductors
are also good heat conductors. The best efficiency is
obtained with semi-conductors
Unfortunately good electrical conductors are also
good heat conductors. The best efficiency is obtained
with semi-conductors.
If temperature difference is created between two
different conductors, ‘a’ and ‘b’ having junctions at
M and N, a voltage difference (V) will be created
between M and N appearing between the two ‘b’
segments Therefore, under open-circuit.
On the hot side the net heat from the cold side and
the power required to pump this heat must be
transferred to the environment.
Qh = Pel + Qc
By changing the direction of the current the heat
flow changes too, from the cooling mode into the
heating mode.
THERMAL FLOWS IN A COOLER