What is meant by figure of merit of thermoelectric material?
The figure of merit. is defined for a thermoelectric generator using the maximum efficiency of the thermoelectric device η calculated from the exact method.
What is the range of ZT value for a good thermoelectric materials?
There is no theoretical upper limit to ZT, and as ZT approaches infinity, the thermoelectric efficiency approaches the Carnot limit. However, until recently no known thermoelectrics had a ZT>3. In 2019, researchers reported a material with approximated ZT between 5 and 6.
What is the ideal ZT for a thermoelectric material to achieve the maximal efficiency?
The higher is ZT , more performant is the thermoelectric material and the better is the TEG. In the practical applications, the maximum ZT is about 2 and corresponds to a maximum conversion efficiency of about 20% .
What is an example of thermoelectric?
Some examples of thermoelectric generator applications include biomass cooking stoves, camping stoves and grills. Solar thermal applications utilize solar energy that is concentrated onto a thermoelectric generator hot side at very high temperatures. The ambient air is used for the heat sink.
What is the formula for ZT?
ZT = Seebeck coefficient squared * absolute temperature * electrical conductivity / specific thermal conductivity the material values must be taken into account as a function of temperature and time. These difficulties can be overcome by measuring the ZT value.
What is meant by the figure of merit?
A figure of merit is a quantity used to characterize the performance of a device, system or method, relative to its alternatives. In engineering, figures of merit are often defined for particular materials or devices in order to determine their relative utility for an application.
What is the figure of merit of the thermoelectric power generator?
Figure of merit is used to determine the efficiency of thermocouples and thermoelectric generators. In the corresponding formulas, the figure of merit appears under the name ZT. A temperature difference at the ends of an electrical conductor causes an electrical voltage in this conductor.
What is the figure of merit of TEG?
Thermoelectric materials generate electricity from temperature gradients. The dimensionless figure of merit, ZT = S2ρ−1κ−1T, is calculated from the Seebeck coefficient (S), electrical resistivity (ρ), and thermal conductivity (κ).
What is thermoelectric diagram?
Thermo-electric Diagram. A diagram indicating the change in potential difference for a fixed difference of temperature between different metals at different temperatures. It is laid out with rectangular co-ordinates. On one axis temperatures are laid off, generally on the axis of abscissas.
How can we increase ZT?
Various properties which influence zT can be improved by using modern technology for creation special submicron structures inside homogeneous thermoelectrics. Barriers for electrons with /spl epsiv/100 is electron gas in vacuum due to full absence of lattice thermal conductivity.
What is the formula of figure of merit?
When a coil carrying current I is placed in a radial magnetic field, the coil experiences a deflection θ which is related to I as I = kθ, where k is a constant of proportionality and is termed as figure of merit of the galvanometer.
What is the SI unit of figure of merit?
Figure of merit is the amount of current been passed in the unit of deflection in a galvanometer. Its SI unit is Ampere per division.
What is thermoelectric power factor?
The dimensionless figure of merit ZT ranks the thermoelectric materials. The higher the ZT-value, the better is the efficiency thermoelectric conversion from heat into electricity. ZT is defined as ZT= S2σT/λ, where the numerator S2σis called the power factor.
Where are thermoelectrics used?
Thermoelectric generators are commonly used on gas pipelines, for example, for cathodic protection, radio communication, and telemetry. On gas pipelines for power consumption of up to 5 kW, thermal generators are preferable to other power sources.
What is thermoelectric effect PDF?
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. Thermoelectric devices create a voltage when there is a different temperature on each side.
What are the uses of thermoelectric diagram?
(i) Determination of Total emf. MN represents the Thermo-electric power line of a mental like copper couple with lead. MN has a positive slope.
How can thermoelectric materials be improved?
One of the best ways of reducing the lattice thermal conductivity is the formation of a solid solution . For example, the compound lead telluride is a useful thermoelectric generator material. Its figure of merit can be further improved by alloying it with the isomorphous compounds lead selenide or tin telluride.