Thermoelectric devices

Thermoelectric devices are made from thermoelectric modules. A thermoelectric module is an array of thermocouples connected electrically in series but thermally in parallel

How do they work?

A thermoelectric device converts thermal energy into electrical energy by using an array of Thermocouples. This device is a reliable source of power for satellites, space probes, and even unmanned facilities. Satellites that fly toward planets that are far away from the sun cannot rely exclusively on solar panels to generate electricity. These satellites will have to use an alternative energy source, such as thermoelectric devices, to generate their power, as in NASA’s Pluto New Horizons spacecraft. Thermoelectric devices for deep-space missions use a radioactive material, like plutonium, to generate heat, and thermocouples to convert the heat to electricity. Since a thermoelectric device has no moving parts, it is reliable and can generate electricity for many years. Studies have been done on improving the efficiency of the thermoelectric generator by incorporating other technologies, like nanotechnology. By achieving a better efficiency, thermoelectric devices would need less radioactive material to produce the same amount of power, making the power generation system lighter. The Less radioactive material will also decrease the cost of spaceflight launches. Although these devices are used mostly in spacecraft technologies, they can be also applied to technologies on earth, which might further contribute to the advancement of technology. Some applications of this technology include automobiles, computers, household appliances, etc.

The image below shows a graph explaining how this system works

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The following video is a detailed explanation showing how this process works:

What are the most common applications for it?

Thermoelectric effects can be used to make solid-state refrigeration devices, or to sense temperature differences, or to convert thermal energy directly into electricity. While the Peltier effect is used within thermoelectric cooling devices, the Seebeck effect is responsible for the conversion of temperature gradients to an electrical voltage.

Peltier effect: Thermoelectric cooling

Thermoelectric cooling uses the Peltier effect to create a heat flux between the junctions of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current.

The image below shows a schematic of a Peltier cooler

Seebeckeffect: Thermoelectric temperature sensing and power generation

This effect is the conversion of a temperature gradient across the junctions of two dissimilar metals to electrical voltage in the range of millivolts per Kelvin difference. The effect is non-linear with temperature and depends on absolute temperature, type and structure of materials.

The picture below is an example Seebeck voltage generator

The Thomson effect

The Thomson effect,” or “Kelvin heat, describes the heat release in a material with a current through it. This heat release is directly measurable. That is unlike the Peltier and Seebeck effects, for which only the net effect of two different materials can be measured. Since the Peltier and Seebeck coefficients can be computed from the Thomson one, in principle the Thomson effect allows all three thermoelectric coefficients to be found without involving the second material.

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Example of thermoelectric devices:

The thermoelectric devices can enhance the energy production of hybrid automobiles by producing electricity using the waste heat of the engine.

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This image shows the inside of GMZ Energy’s TEG module. When waste heat enters the top of the module and moves through the semiconductor material (shown here as P and N) to the cooler side, the resulting temperature difference creates a voltage that’s extracted as electricity. Credit: Screenshot from a video by GMZ Energy