What is thermoelectric technology?
Solid State Cooling Systems utilizes thermoelectric technology to precisely control temperature as an alternative to traditional recirculating chillers which use compressors and refrigerants, such as Freon, to control temperature.
The heart of our systems is a thermoelectric heat exchanger which is made up of a liquid cold plate, thermoelectric modules to precisely control the temperature of the recirculating fluid and some means of disposing of waste heat, either using heat sinks and a fan or using facility process chilled water.
Thermoelectric modules leverage an electrical phenomenon called the “Peltier effect”, which was discovered back in 1834 by Jean Charles Athanase Peltier, but was not broadly used in commercial applications until semiconductor technology advanced in the late 1900s. Now, thermoelectric modules are found in a wide variety of products around the world.
Each thermoelectric module is made up of a series string of different types of semiconductor blocks sandwiched between two ceramic plates. The semiconductor block materials are carefully selected to provide high electrical conductivity with low thermal conductivity across the junctions. As a result, when a precise electrical current is sent through the module, a precise thermal differential is achieved between the two ceramic plates. Reversing the direction of the current reverses the temperature differential, so thermoelectric modules can be used to heat or cool.
How do thermoelectric chillers compare to compressor-base chillers?
By leveraging thermoelectric technology, Solid State Cooling Systems is able to offer recirculating chillers, which are more reliable, smaller, quieter and more energy-efficient than traditional compressor-based chillers.
Our thermoelectric chillers are also environmentally friendly, using no harmful refrigerants. More and more countries around the world are enforcing new regulations built upon the Montreal Protocol, which is driving the continued reduction and eventual elimination of many harmful refrigerants used in compressor-based chillers.
For more information on the global activities to eliminate harmful refrigerants, click here.
Energy savings with thermoelectric chillers compared to compressor-based chillers is even more dramatic, when precise temperature control is required. The most common techniques used to make a compressor-based chiller “precise” is to add a hot gas bypass or heater loop to add more control to the compressor, which in most chillers is either on or off. This makes these systems very inefficient. Thermoelectric chillers, by design, control temperature very efficiently. The system just adjusts the current to achieve an exact control temperature. Using this approach, our chillers are up to 80% more energy-efficient than compressor-based systems.
The table below shows the benefits of thermoelectric chillers compared to compressor-based chillers:
What makes Solid State Cooling Systems chillers so reliable?
Solid State Cooling Systems has established a strong, positive reputation for producing products which are significantly more reliable than compressor-based chillers. At least part of this improved reliability is inherent in the use of thermoelectric technology. Compressors typically have shorter lifetimes, because they continually run. Even variable speed compressors will wear out faster than thermoelectric technology. Thermoelectric modules have a typical lifetime of 200,000 hours. By using thermoelectric modules, with only one or two moving components (a pump and a fan), our products are inherently more reliable.
Another important factor in the lifetime of our chillers is our design approach. Although thermoelectric chillers are generally more reliable than compressor chillers, the approach to powering the modules is critical. Not all thermoelectric chillers are the same. Over our more than 25 years in business, we have developed a proprietary approach to configuring and powering our thermoelectric heat exchangers to ensure longer life.
Unlike compressors, our thermoelectric modules only turn on when needed. Once the targeted (Set Point) temperature is achieved, the feedback loop dials down the power on the modules. Power is only applied to precisely maintain a Set Point temperature.
Many of our products actually use a redundant design, so that if a thermoelectric module does fail over time, the chiller will keep working, just with reduced cooling capacity. In applications where the capacity of the chiller is higher than the max heat load, customers may not even know that a module has failed.
The last important factor in ensuring our products have world-class reliability are our proprietary assembly procedures and the skills of our assembly team. As an ISO 90001 certified manufacturing business, we pride ourselves on the discipline and attention to detail in production.
Types of Thermoelectric Heat Exchangers
We use two main types of thermoelectric heat exchangers in our products. The primary difference between the two is the way waste heat is removed from our systems.
Liquid to Air Heat Exchangers
In Liquid to Air heat exchangers, a recirculating process fluid (water/glycol, Galden/Fluorinert, PAO or other fluid) is cooled on one side of the thermoelectric modules, while heat is rejected into a finned heat sink with a fan to rapidly dissipate the heat into air. Liquid to Air heat exchangers are used in most of our benchtop products and some of our rackmount products.
Liquid to Liquid Heat Exchangers
In Liquid to Liquid heat exchangers, a recirculating process fluid (water/glycol, Galden/Fluorinert, PAO or other fluid) is cooled on one side of the thermoelectric modules, while heat is rejected into recirculating Facility Water or Process Chilled Water (PCW). Liquid to Liquid heat exchangers are used for higher capacity applications where PCW is generally available. Most of our semiconductor products use Liquid to Liquid heat exchangers, because PCW is generally available and customers want to minimize air movement in cleanrooms.