Summary of TEC used in Free Space Optics

Thermoelectric Cooler (TEC) devices are used in some CableFree FSO products to cool the actual laser devices. Since Free Space Optics equipment is often installed outdoors and subject to wide temperature fluctuations, TECs help ensure consistent laser performance and longevity by keeping the temperature within a safe operating range.

FAQ on TEC devices

What is a thermoelectric module?

A thermoelectric module is a small solid state device that can operate as a heat pump or as an electrical power generator. When used to generate electricity, the module is called a thermoelectric generator (TEG). When used as a heat pump, the module utilises the Peltier effect to move heat and is called a thermoelectric cooler (TEC).

What is the Peltier effect?

The Peltier effect, discovered in 1834, causes a temperature change when electric current flows through the junction of two different conductors. Its practical use in TECs became possible with the development of semiconductors that conduct electricity well but heat poorly. Bismuth telluride is the primary material used today, heavily doped to create n-type (excess electrons) and p-type (electron deficiency) semiconductors.

How does a TEC work?

A TEC consists of multiple p- and n-type pairs connected in series and placed between two ceramic plates. When powered by DC, the current moves heat from one side of the TEC to the other, creating a cold side and a hot side. The cold side cools the target object, while the hot side requires a heatsink (and often forced air or liquid cooling) to dissipate the heat. TECs don’t eliminate heat, they just transfer it.

What happens if I reverse the direction of the current?

If the current is reversed, the heat is moved in the opposite direction. In other words, what was the hot face becomes the cold face and vice-versa.

How much heat can it pump? Could it cool a house?

The maximum amount of heat the largest single TEC can pump is about 125 W. So, it could not cool a house! However, our modular design enables you to use several TECs per application, allowing you to move more heat.

So, I can use more than just one?

Sure! They can be used side-by-side to increase the amount of heat pumped, or stacked on top of one another (as “cascades” or multistage TECs) to increase the temperature difference across the TEC. Single-stage TECs are appropriate when the temperature difference between the hot and cold faces does not need to exceed 60°C, otherwise cascades should be considered. Some cascades are listed in the Multistage Specification table. Many others are available.

When should I use a TEC? Is a TEC as good as a compressor?

TECs are perfect for some applications and completely unsuitable for others. Depending on the application, a TEC can be much better than a compressor or no match at all. TECs are very small, very light weight, and completely silent. With no moving parts, they are extraordinarily reliable. TECs generate little, if any, electrical noise and can provide precision temperature control when used with an appropriate controller. They can be operated in a vacuum or weightless environments, and in any physical orientation. On the other hand, TECs tend to lose their competitive advantage when cooling loads exceeding 200W. Under some special circumstances, however, TECs are used to pump loads of tens of kilowatts.

Is it hard to design a TEC for my application? Do I need special equipment or training to install a TEC?

Using a TEC does require some understanding of heat transfer and a good grasp of your application. Our experienced engineers are available to help you. Proper installation is extremely important but not very difficult. We can also build custom subassemblies for specific applications.

What about temperature control and power supplies?

TECs are DC devices. The amount of heat pumped through the TEC is directly proportional to the power supplied. Temperature is controlled through manual or automatic means. The automatic controller can range from a simple on-off thermostat to a complex computer controlled feedback circuit. Precision TEC control systems are built in as standard to FSO products available from CableFree.

For Further Information

Please Contact Us