Thermal generator works on the
concept of Seebeck effect. According
to Seebeck effect, one side of the device is heated up in a manner that its
temperature is greater than the other side and hence difference in voltage will
be established. It is also called as thermoelectric
generator or Seebeck generator. It
can be defined as a solid state active device that is used to convert the heat
directly into electrical energy by using the concept of seebeck effect. It also
exchanges electrical energy into thermal power energy for heating or cooling.
Configuration of the thermal Generator:
The elevated temperature is
provided by the heat source which flows directly to heat sink through thermoelectric
converter. Heat sink is always
maintained at below temperature as compared to heat source. This difference of
temperature is responsible to produce direct current (DC) for current loading
(RL) using a terminal
voltage (V) and terminal current (I). Thermoelectric power generator is also
classified as direct power conversion as they don’t have intermediate energy
conversion process. Electrical powers are generated through l2, RL and VI. Consider the
following figure:
Traditionally only three types of
thermoelectric material are used in semiconductor for low thermal conductivity
and high power factors which are bismuth tellurides (Bi2Te3),
lead telluride (PbTe) and silicon germanium (SiGe). These materials are
expensive compound because of rare availability. Hence, now a day,
nanotechnology is being used for thermal conductivity of semiconductors,
however, manufacturing of nano materials are still very challenging.
Uses of thermal generator:
· In power plants to convert waste heat into additional electrical power
· In automobiles as automotive thermoelectric generators to increase fuel efficiency
· Radioisotope thermoelectric generator as space probes
· To construct fossil fuel generators
· Solar source generators
· Nuclear fueled generators
Working of thermal generator:
Thermal generator generates the
electricity by moving of electrons. Electron moves in a metal just like fluids
flow in pipe. At the time of heating of thermoelectric material electron move
speedily from hot end to cold end which causes electric current. When the large
temperature difference is created by electrons, more electric current will
produced and hence more electric power is generated.
Now the problem arise is that
when start the heating process, cold side of the generator also starts heating.
Nevertheless, we need a temperature difference between thermoelectric materials
to generate electricity. This task is accomplished by heating water in the
power pot to create heatsink as water can keep more heat several times as
compared to aluminum per pound. The water can maximum hotter by 212F (1000C)
at a boil. Thus, the cold side of the thermoelectric generator is limited to
this capacity. So, we always need a something watery in the powerpot to avoid
overheat of generator.