Some major applications of thermoelectricity are discussed as under.
Thermoelectric thermometer:
- One junction of the thermocouple is kept at a constant temperature and the other is brought in contact with the body whose temperature is to be measured. Thermo-emf produced can be calibrated to indicate the temperature of the body.
- Temperatures ranging from very low temperature to 2000 K can be measured this way.
Thermocouple Range of temperature measured
(1) Copper-constantan 50 K to 500 K
(2) Iron-constantan up to 1000 K
(3) Platinum-Rhodium alloy and}
Copper-aluminum alloy } up to 2000 K
(4) Copper and Gold-Iron alloy 1 K to 50 K
- To measure low temperatures, thermocouples should be made of metals which give large emf for small differences of temperatures.
Thermoelectric generator:
- Electricity can be generated on a very small scale using Seebeck effect.
- Efficiency of thermocouples being very low ( about 1 % ), voltage of 0.1 mV / K and power of 0.25 mW / K can be obtained using thermocouples prepared from semiconductors.
- Low power thermoelectric generators ( up to 5 kW capacity ) keeping one junction at room temperature and heating the other with a kerosene lamp have been developed for use in remote areas.
Thermoelectric Refrigerator:
- Thermoelectric fridge is prepared using Peltier effect with the help of junction at which temperature decreases on passing electric current.
- They can be used for cooling of small areas as they have low efficiency.
- They are noiseless as there are no moving parts like a motor.
- They are pollution-free as there is no refrigerant gas like Freon which destroys the ozone layer. Hence, there is a scope to develop such fridges by improving their efficiencies.
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