Since there isn’t much information available online, we’re here to help explain the fundamentals of how thermoelectric generators (TEGs) work.
A temperature difference and heat flow are transformed into a useful DC power source by thermoelectric generators (TEG), which are solid-state semiconductor devices. The Seebeck effect is used by semiconductor thermoelectric generators to create voltage. This voltage is created and drives electrical current, producing useful power at a load.
Thermoelectric Generators (TEGs) operate according to the following principle.
Working Principle 1: Seebeck Effect
When different metals are subjected to temperature variations, the Seebeck Effect results in the generation of an electric current. Applications of the Seebeck effect form the basis of thermoelectric generators (TEGs) or Seebeck generators, which transform heat into energy. When using TEGs or Seebeck generators, the voltage output is inversely proportional to the temperature difference across the two metal junctions.
Solid-state heat engines known as thermoelectric generators are constructed from pairs of p-type and n-type elements. The semiconductor materials used to create the p-type elements have been doped so that the charge carriers (holes) are positive and the Seebeck coefficient is positive.
The semiconductor material used to create the n-type elements has been doped to have negative charge carriers (electrons) and a negative Seebeck coefficient.
Working Principle 2: Peltier Effect
This effect applies power to the module, cooling one side and heating the other as a result. These modules have low amp ratings (typically in the 6 amp range) and are made to withstand hot side exposure temperatures of no more than 130 to 140 degrees Celsius.
They are not reliable power generators because higher temperature exposures will either cause the module to disintegrate or the soldered couples to fail under strain.
Critical Factors Dictate Power Output
There are two critical factors that dictate power output:
- The amount of heat flux that can successfully move through the module (HEAT FLOW)
- (DT) Delta Temperature – the temperature of the hot side less temperature of the cold side
The Amount of Heat Flux
How much heat can be successfully transferred through the module? More power can be produced the more heat there is. The amount of power that can be produced is constrained, for instance, when a candle is used as the heat source. If you can access the direct heat inside a wood stove with a 100,000 BTU rating, you can generate enough power to charge a 12 or 24V battery system.
(DT) Delta Temperature
The heat input design, in particular, must be given a lot of attention, as must the heat removal design (cold side). The more efficiently heat is transferred from the hot side to the cold side and then dissipated there, the more power can be produced by the TEG Generator System.
Thermoelectric Seebeck Effect modules are made for very high power densities, in contrast to solar PV, which uses large surfaces to generate power. approximately 50 times more than solar PV! Moving liquid on the cold side Thermoelectric Seebeck Generators perform noticeably better than any other cooling technique and produce noticeably more net additional power than a pump consumes (based on system size).
The best thermally conductive materials, such as aluminum and copper, would therefore be needed to build the Thermoelectric Generator system in order to move heat as efficiently as possible.
What Semiconductor Materials Are Used for Thermoelectric Generators?
For thermoelectric generators, three materials are frequently used. These substances are silicon germanium (SiGe), lead telluride (PbTe), and bismuth telluride (Bi2Te3). Depending on the characteristics of the heat source, cold sink, and thermoelectric generator design, a particular material is used.
Although they have not yet been commercialized, numerous thermoelectric generator materials are currently being researched.
What is a Thermoelectric Generator Module?
Numerous p-type and n-type couples are electrically connected in series, parallel, and/or other configurations to produce the required electrical current and voltage in a thermoelectric generator module.
The couples are sandwiched between two parallel ceramic plates. The plates have a dielectric layer to stop electrical short circuits, structural rigidity, and a flat surface for mounting.
What Are the Advantages of Thermoelectric Generators?
- Reliability – Solid-state devices are thermoelectric generators. They are very dependable since they have no moving parts to wear out or break. Thermoelectric generators are very durable. The thermoelectric generator on the Voyager 1 spacecraft has been in use for 41 years as of this writing. Without any maintenance or repairs, it has logged more than 13 billion miles of travel.
- Quiet – It is possible to design thermoelectric generators to be completely silent.
- No Greenhouse Gases – No greenhouse gases are needed for the operation of thermoelectric generators. Some technologies for converting energy do.
- Wide Range of Fuel Sources – The types of fuels that can be used to produce the necessary heat with thermoelectric generators are not constrained. This is true of many other energy conversion technologies.
- Scalability – The power levels that thermoelectric generators can produce range from microwatts to kilowatts.
- Mountable in Any Orientation – A thermoelectric generator can run in any direction. Some energy conversion technologies are sensitive to their orientation with respect to gravity.
- Operation Under high and Zero G-forces – High-G or zero-G operating conditions are both possible for thermoelectric generators. Other energy conversion technologies can’t, though.
- Direct Energy Conversion – Electricity is produced by thermoelectric generators by converting heat. In order to convert heat to electricity, many energy conversion technologies call for intermediary steps. For instance, the heat energy from the fuel is transformed into mechanical energy in a turbine, and then the mechanical energy is transformed into electrical energy in a generator. Losses in the form of waste heat are added with each energy conversion step. Because of this, thermoelectric generators are mechanically simpler than some other energy conversion technologies.
- Compact Size – It is possible to create very small thermoelectric generators. More design flexibility results from this.
Conclusion: Working Principle of Thermoelectric Generators
The Seebeck effect, a type of thermoelectric effect, is a phenomenon that allows a solid-state device known as a thermoelectric generator (TEG), also known as a Seebeck generator, to directly convert heat flux (temperature differences) into electrical energy.
Like a thermoelectric generator, a thermoelectric cooler operates in the opposite direction. In a thermoelectric cooler, an electrical current is created when a voltage is applied. Inducing the Peltier effect is this current. As a result, heat is transferred from the cold side to the hot side.
FAQs
What Temperature is Needed for the Thermoelectric Generator?
Low-temperature materials, in which the working temperature is around 400 K. In this temperature range, bismuth-based alloys are among the frequently used materials [40]. Materials that operate best at intermediate temperatures, which range from 600 to 900 K. In this category, lead-based alloys are frequently used.
How Many Volts Does a Thermoelectric Generator Produce?
The 10 tegs are wired up in 2 parallel strings and, from the manufacturer’s specification, the optimum output voltage is 14.4v.
