Peltier Module is a solid state active device which is often
used for generating the cooling effect. Hence used in many applications for
industrial and household things. Because of cooling facility they are used to
design some portable coolers which can be used to carry food to the beach or in
water dispenser.
They are not as much efficient as only approximately 5%
electrical energy used to power them, is enough for cooling. Hence we planned a
simple efficiency test as shown in the picture. Here we will not test the
module directly. Instead of it we will test the efficiency by the time it could
cool the 250 ml of water and how much cool the water is.
Please note that mainly two different types of peltiermodules are used mostly – Thermoelectric coolers (TEC) and Thermoelectric
Generator (TEG). TEC is used to generate the cooling effects and hence used for
refrigeration system while TEG used for converting the temperature difference
into electricity.
Here we will test thermoelectric coolers. Please consider
the below image of water dispenser from the back and also the parts I took from
for this testing.
How Peltier Module
Works?
The peltier module was stuck to the back of heat sink with
thermal paste. A fan is attached to another side of heat sink for sucking the
air through the fan and carry away heat through it. The whole thing was sat up
on jars so there'd be room below for the air to flow away.
A thermocouple is inserted between the separate containers
of warm water. The peltier module will be shut off by the control board if the
thermocouple keeps the right temperature of water for water dispenser. We did
not concentrate on maintaining the temperature. Instead of it, I tricked it by sitting
it in water whose temperature would never change. As a result the control board
wouldn't shut off the Peltier module for that reason.
We next
sat a square piece of aluminum on the Peltier module to transfer heat from the
can more effectively, which would be sitting on top of the all of the module's
surface. Also we sat a soda can on the top and top is opened and bottom is
flattened as much possible. After this; insulation is added around
the top to take heat from the water in the can instead of surrounding air. Next,
we poured 250 ml of water. A thermometer was then inserted inside, one that
could measure cold temperatures. And lastly, the hole in the top of the can was
covered with more insulation.
Finally oscilloscope I connected
in parallel with the electrical output of the control board going to the
peltier module. After this; ammeter was connected in line with the positive
wires going from the control board to the Peltier module. The circuit was
turned on using the on/off switch and the starting water temperature was
recorded. The voltage and current had an initial few second long surge and then
settled down. Their values were then recorded.
