Thermoelectric Generators: The New Revolutions of Power Generators

Thermoelectric generator is a class of solid state active devices which works on the phenomenon of seebeck effect. The device is used to either convert the heat energy directly into electricity or vice versa means transform electrical energy into thermal energy for generating the heat or cool effect. The see beck effect or thermoelectric effect accomplish this task by a process of generating electric current by thermocouple and keeping the connection formed by two different metals at different temperatures. The efficiency goes up to 5 to 10 percentage.

Now a days may types of thermoelectric generator are available in market for various purposes like Radioisotope thermoelectric generators, household generators, industrial power generators and automotive thermoelectric generator. All these power generators are used for mainly used in applications like heat engines and sterling engines. The engines that produce more heat waste like combustion engine are mostly used for this type of applications. However, glaring problem which appears in such situations is output resistance and adverse thermal characteristics.

It seems that they work just like same as engine powered generators to produce electricity yet there is major difference. The ordinary engines give very annoying sound whereas the thermal generators form the electricity silently or do not produce noise while working. The main reason behind this is that electricity is produced by TE generators without the movement of any part instead of a cooling fan.

It is right to say that this is revolutionary engine temperature is cool down by the cooler when it flows from the burner to many thermo an electric device towards the direction of cooler. A voltage is created across the generator by the thermal flow of thermal energy.

The flow thermal power in TE generators creates a very high voltage across the thermocouples and causes very high voltage circulations in the primary ring due to high performance crystalline semiconductors.

The thermoelectric generators are highly reliable because of its strong construction. Hence, this is being used in many military and aerospace applications for several years. Hence the same is being used in many military and aerospace applications for several years. This is because of its main features; the power can be concentrated or consolidated to maintain an ample output to rum many applications at same time. The patented internal circuit, which converts the generated amperage into effective voltage, is the main feature of it. And hence most of industries are using it.

Ferrotec Nord is one of the leading manufacturing companies of thermoelectric products. They produced more than 250 designs of Peltier modules of various design, capacity, voltage, supply current and geometry to meet the demand of the thermoelectric module market and specific customer needs.  Also if the customer does not found the same according to his requirements, they are ready to design in accordance with their requirement of special geometry, shape, specifications or special use.

For further information visit @ http://ferrotec-nord.com

Let’s Know about Bismuth Telluride Thermoelectric Material

Thermoelectric materials are used in thermoelectric device for generating cooling and heating effects. The most common uses of these materials are to regenerate the electricity from waste heat at electric power plants. These are available as per high strength or low cost materials. The low cost materials which have strong sufficient thermoelectric effect are used in applications including power generations and refrigeration. We mostly use in such applications bismuth telluride (Bi₂Te₃) thermoelectric material.

Basically for manufacturing high quality thermoelectric module, the selection of thermoelectric material is affected by several factors such as:

·        Electrical Conductivity

·        Thermal Conductivity

·        Seebeck Coefficient

·        Temperatures Change Behavior

 After choosing a material its usefulness is decided by the material’s power factor and device efficiency.

As most of the company use high-efficiency material Bi₂Te₃ and high temperature solders for generating thermoelectric modules, so we discuss about this in detail.

Bismuth Telluride (Bi₂Te₃):

It is a grey powder which is compounded from bismuth and tellurium. We also know this as bismuth (lll) telluride. For portable power generation and refrigeration we alloy this thermoelectric material with antimony and selenium in a semiconductor. It is also known as topological insulator and hence exhibits many thickness dependent physical properties.

Why use as thermoelectric material?

Bismuth telluride has a thin gap layered semiconductor which has trigonal unit cell. Due to van der waals bonding, it cleaves easily along with trigonal axis between neighboring tellurium atoms. Because of this feature we always use polycrystalline bismuth telluride (Bi₂Te₃) for power generation and cooling applications. Apart from this, the Seebeck coefficient of bismuth telluride metal becomes compensated around the room temperature. Due to which it is forced to be used in power generating devices and having the alloy of bismuth, antimony, tellurium and selenium.

As bismuth telluride thermoelectric material and its solid solutions are good at room temperature, hence, it is also suitable for refrigeration applications around 300 K. A method named Czochralskiis used to grow single crystalline bismuth telluride compounds. These compounds are produced with directional solidification from melt or powder metallurgy processes. The produced material has superior mechanical properties and sensitive to structural defects and lower impurities due to high optimal carrier concentrations.For more information visit @ http://ferrotec-nord.com/support/thermoelectric-modules

Let’s Know about Thermal Generator!

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 (R_L) 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, R_L 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.