How Thermoelectric Modules Harness Temperature Differences

Many pieces of technology greatly benefit from devices that dissipate heat or convert excess thermal energy into usable electricity. Thermoelectric modules are uniquely positioned to meet both demands, relying on temperature differences to do so. This blog will explore the basics of how thermoelectric modules function and their variations, clarifying their role in the current technology landscape.

What Is a Thermoelectric Module?

A thermoelectric module is a solid-state device that converts thermal energy directly into electrical energy, or vice versa, operating based on two principles:

1. The Seebeck Effect: When two sides of the module are kept at different temperatures, the imbalance causes charge carriers in the semiconductor materials to move and produce an electrical voltage.
   
2. The Peltier Effect: When an electrical current is passed through the module, it drives charge carriers in a way that moves heat with them. One side of the module becomes cooler while the other becomes hotter, letting it act as a solid-state heat pump.

Most thermoelectric modules can technically operate in both modes, but this tends to degrade their performance. As such, they are usually tailored to excel in one domain, being categorized as either:

• Power Generation Modules: These modules are optimized to harvest electricity from available heat sources. They are most effective in environments with continuous waste heat, where they provide a very compact and silent means of generating supplementary electricity.
• Cooling Modules: Designed to transfer heat from one side of them to another when current is applied, cooling modules are employed in electronics where accurate, stable temperature regulation is needed, such as laser diodes and medical devices.

Internal Components

Usually, thermoelectric modules are composed of multiple small semiconductor elements like:

• N-Type and P-Type Semiconductors: N-type semiconductors carry negatively charged electrons, while P-types carry positively charged “holes.” When a temperature difference is applied across the module, electrons in the N-type and holes in the P-type move from the hot side toward the cold side, transferring heat and also creating an electric current when the elements are connected in a circuit. Inside the module, dozens to hundreds of these N-type and P-type elements are arranged in alternating pairs. They are linked electrically in series, so the voltage contributions of each pair add together, and thermally in parallel, so heat flows evenly through all elements from the hot side to the cold side. 
• Metallic Contacts: Metallic contacts connect the individual semiconductor pairs so current can flow between the module and the external circuit with minimal resistance.
• Ceramic Substrates: The substrate provides mechanical support for the semiconductor elements, contributing to thermal insulation and electrical isolation between the hot and cold sides. The ceramic layers also protect the module from mechanical stress and thermal expansion.

Limitations to Consider

Like any technology, thermoelectric modules have their share of advantages and drawbacks that need to be balanced. As far as their limitations, these modules present:

• Moderate Efficiency: Most power generation modules operate with efficiencies in the range of 5 to 8%, considerably lower than the 30 to 40% that many conventional energy conversion systems achieve. This limitation arises from the properties of current semiconductor materials, which restrict how well heat can be converted into electricity.
• Higher Thermal Management Requirements: Thermoelectric modules rely heavily on maintaining a strong temperature gradient across their surfaces. Without the use of heat sinks, fans, or liquid cooling, they can experience rapid performance losses. In power generation variants, insufficient heat dissipation limits their voltage, while those meant for cooling have a reduced ability to pump heat.
• High Cost for Large-Scale Uses: While excellent for small or supplemental applications, their relatively high cost of manufacturing and modest output makes thermoelectric modules less competitive than conventional generators or other renewable technologies when applied at large scales. Similarly, thermoelectric cooling modules are restricted in how much heat they can move. Unlike compressor-based refrigeration systems, they are not practical for high-volume or large-space cooling.

ASAP Aerospace: A One-Stop Source for Thermoelectric Modules

The key takeaway is that while thermoelectric modules may not match the sheer scope of more traditional systems for energy conversion or thermal management, they are versatile devices that operate in a quiet and very precise manner without taking up a lot of space. For organizations who hope to utilize these modules, ensuring their performance depends on using them in the appropriate applications and purchasing options that are manufactured to rigorous standards. 

Through ASAP Aerospace, you can access an extensive catalog of top-quality thermoelectric modules and other related components. All offerings are sourced from reliable manufacturers and ready for purchase with competitive, tailored sourcing solutions. With this being said, see how we can serve as your go-to procurement platform by checking out our selection and connecting with our expert team today.