HVAC School - For Techs, By Techs
The Tech That Tried to Beat the Compressor - Short #268
· Summarized
Key takeaways
- Thermoelectric cooling, based on the Peltier effect, allows for cooling without moving parts or refrigerants.
- The history and development of this technology have been influenced heavily by advancements in semiconductor materials.
- Current thermoelectric systems face significant efficiency challenges, limiting their applications compared to traditional methods.
- Staying curious and open to innovations is vital as future HVAC solutions may arise from developments in solid-state technologies.
Summary
Introduction to Thermoelectric Cooling
In this episode, Bryan introduces the concept of thermoelectric cooling, specifically focusing on the Peltier effect discovered by Jean Charles Athanase Peltier in 1834. He explains how Peltier's experiments with electricity and different metals led to the discovery of a phenomenon where electrical current can transfer heat, allowing for cooling without traditional compressor systems.
The Evolution of Thermoelectric Technology
Despite its initial obscurity, the discovery gained traction with the advent of semiconductors in the mid-1900s, enabling practical applications in NASA spacecraft and later on Earth in devices like mini fridges and CPU coolers. Bryan outlines the advantages and applications of thermoelectric devices, particularly in environments where reliability is more critical than efficiency.
Challenges of Thermoelectric Systems
Bryan discusses the ongoing limitations of thermoelectric technology, primarily its low efficiency (only around 5-10% compared to traditional vapor-compression systems) and the challenges in dissipating waste heat. Despite advancements, engineers continue to seek better materials to enhance the efficiency of thermoelectric systems. The conversation emphasizes the ongoing need for improved performance to make thermoelectrics viable for broader applications in HVAC.
The Future of HVAC Technology
The podcast speculates on the potential future of heating and cooling technologies, suggesting that the next breakthrough might emerge from solid-state designs using advanced thermoelectrics. Bryan encourages listeners to think outside the box and stay curious about emerging technologies that may not fit traditional models, urging them to consider the evolving landscape of energy-efficient systems.
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Show notes
In this short podcast episode, Bryan tells the story of the technology that tried to beat the compressor... and still may someday.
We associate cooling with refrigerant... and all the things that come with it, including compressor noise, oil, recovery machines and tanks, leaks, superheat, and regulations. However, there is a means of providing cooling with two pieces of metal and several semiconductors; current runs through it, and one side becomes cold, and the other side becomes hot. This technology is called thermoelectric cooling, associated with the Peltier effect.
In 1834, French watchmaker and amateur physicist Jean Charles Athanase Peltier was experimenting with electricity and dissimilar metals. When he joined two wires of different materials and ran current through the junction, one got colder, and the other one got hotter. This phenomenon was named the Peltier effect, and it describes how passing electrical current through two dissimilar conductors causes heat to move from one side to the other, like a tiny reversible heat pump. However, it didn't have any practical use at the time.
Semiconductors arrived in the mid-1900s, and engineers could make thermoelectric devices strong enough to move meaningful amounts of heat. In the 1960s, NASA even began using the technology in spacecraft for precision temperature control, which was hardy and allowed them to stabilize sensors and electronics in space. We began using them on Earth in some specialized applications, including portable coolers, wine chillers, and CPU coolers in computers.
However, this technology didn't replace vapor-compression refrigeration due to efficiency constraints and the need to reject heat. Thermoelectric modules are only 5-10% as efficient as vapor-compression systems, and they need heat sinks or fans to give the heat somewhere to go. We've still been pursuing a comfort cooling use of the Peltier effect, and we've gotten closer, but most applications still have the efficiency block. When efficiency isn't a problem, we encounter difficulties with moisture and latent heat removal. Nevertheless, thermoelectric cooling is still making a difference for sensors and in localized cooling applications.
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