Thermoelectric
Refrigeration
Presented By
● Introduction
DIVYANSHU MISHRA ● Comparison
100 ● Basic principles
1814110274 ● Advantages
DEVANSH RAI
● Disadvantages
108 ● Thermoelectric
1814110326 materials
● Applications
Introduction
• One cannot refuse the use of refrigeration systems in our life, not only in kitchen but also in
shops, industries and commercial purposes.
Today's compression refrigeration system has given very goo d performance. But refrigerants used
in these systems are hazardous to the environment and human life, because they react with very
useful gas ozone (O3), thereby depleting ozone layer.
• Thermo-electric refrigeration system can substitute vapor compression refrigeration system for
small-scale applications and act as solution of the problem above discussed
Thermoelectric Refrigeration
•In Thermo-Electric refrigeration, essentially nothing has changed. The refrigerant in both
liquid and vapour form is replaced by two dissimilar conductors.
•The cold junction (evaporator surface) becomes cold through absorption of energy by the
electrons as they pass from one semiconductor to another, instead of energy absorption by
the refrigerant as it changes from liquid to vapor.
•The compressor is replaced by a DC power source which pumps the electrons from one
semiconductor to another. .A heat sink replaces the conventional condenser fins, discharging
the accumulated heat energy from the system.
The difference between the two refrigeration methods, then, is that a thermo-electric cooling
system refrigerates without the use of mechanical devices and without a refrigerant
Project objective
Basic Principles
Peltier Effect- when a voltage or DC current is applied to two dissimilar conductors, a circuit
can be created that allows for continuous heat transport between the conductor's
junctions.
Seebeck Effect-is the reverse of the Peltier Effect. By applying heat to twodifferent
conductors a current can be generated.
The current is transported through charge carriers (opposite the hole flow or with electron
flow).
Heat transfer occurs in the direction of charge carrier movement.
Applying a current (e carriers) transports heat from the warmer junction to the cooler
junction
Refrigeration based of Peltier Effect
It is obtained by arranging a series of thermo-electric cells in a horizontal array which is then
encased in plates made of an electrical insulator. Each thermo-electric cell consists of a pair of
dissimilar semi-conductors (called modules) which are connected by electrical conductors at
either end..
The passage of electric current through them causes one of the plates to become hot and the
other to become cold. When there is adequate cooling to the heated plate, the opposing plate can
reach a low temperature or extra heat on a continuous basis.
The Coefficient of Performance (COP) of a Peltier module is defined in the same way as for a
conventional refrigeration system:
Coefficient of Performance= Rate of heat extraction divided by Electrical Power input.
Critical materials parameters to ensure a high COP are a high thermo electric coefficient to
generate the cooling effect, a high electrical conductivity suppress Ohmic heating and a low
thermal conductivity to prevent much heat to being conducted from the hot side of the module to
the cold side of the module..
ADVANTAGES
Environmental friendly
75% 42%
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DISADVANTAGES
Thermoelectric materials
Those are the materials that can be used to convert thermal energy into
electrical energy or provide refrigeration directly from electrical energy.
Semiconductors are the optimum choice of material to sandwich between two
metal conductors because of the ability to control the semiconductors' charge
carriers, as well as, increase the heat pumping ability.
e.g.: Bismuth Chalcogenides, Lead telluride etc.
Alternatives:
1. Lead telluride and its alloys.
2. Materials based on Nanotechnology.
3. Silicon Germanium.
Applications
>1.THERMOELECTRIC
GENERATOR
➤2.TEMPERATURE CONTROL IN
MISSILES
➤3.TELECOMMUNICATION
EQUIPMENTS
4.SPACE PROBES
5.COOLING COMPUTERS
6.FOOD INDUSTRY
➤7.MEDICAL EQUIPMENT
8.DRINKING WATER COOLER
Future of Thermo-electric Refrigeration
The use of thermoelectric devices and systems has been limited by
their relative low energy conversion efficiency. Present commercial
thermoelectric devices operate at about 10% of Carnot efficiency.
Today's thermoelectric devices are particularly useful when the
efficiency is a
less important issue than small size, low weight, or high reliability
It is important to note that the COP of thermoelectric coolers increases
significantly with decreasing the temperature lift.
References
http://mechanicalgarage.blogspot.in/2013/08/thermoelectric refrigeration.html
• http://www.nextbigfuture.com/2008/08/thermoelectrics-and refrigerators.html
• http://engineersedge.weebly.com/uploads/4/6/8/0/4680709/thermo electric
refrigeration.pdf
