Cryocoolers are essential parts of the cryogenic industry, providing the cold temperatures needed to guarantee cryogenic substances are safely and efficiently maintained. Learn what exactly are cryocoolers and their main applications, as well as the way the main types of cryocoolers work.
What is a cryocooler?
Cryocoolers are refrigerators designed to reach cryogenic temperatures. The term typically refers to small-sized systems (table-top sized) whose input power is less than 20 kW but which can reach temperatures between 10 K to 120 K.
Generally, cryocoolers are expected to be lightweight and present a small volume, as well as cool down quickly and with no vibrations. Finally, the most sought-after systems will present easy and spaced maintenance needs.
How do cryocoolers work?
Most cryocoolers work using cryogenic fluids, which are moved around by a series of moving parts, generating a thermodynamic cycle.
At the same time, there are two basic ways in which cryocoolers work:
- Regenerative systems use flow and pressure in an oscillating manner in order to attain the desired refrigeration. This means these systems often use pressure oscillators but not displacers.
- Recuperative systems work by moving fluids around a loop at pre-established high and low pressures. In order to achieve cryogenic temperatures, the liquid is compressed at room temperature, then cooled by a heat exchanger to be later expanded at a low temperature, depending on the specific needs for the system.
This type of cryocoolers need reciprocating pistons or unidirectional compressors without valves. Maintenance also means the use of oil-removal tools, to guarantee oil remains don’t freeze. Other parts include orifices, capillaries and valves or expansion engines, in order to generate the right low-temperature expansion.
Cryocoolers: the main parts
As explained above, there are different types of cryocoolers, which present their own specific needs in terms of tools and technical parts. However, there are at least two main parts that are typically used in cryocoolers:
- Heat exchangers: these parts cool down the cryogenic fluids, a process that typically happens at a constant pressure. Heat exchangers can be both regenerative or recuperative.
- Regenerators: this part is made of multiple granular particles or other solid porous materials which allow for gases to flow between them, so that heat is both released and stored thanks to this system.
Applications of cryocoolers
- Liquefaction of gases in order to make them more easily and efficiently transported and stored. Many industries are in need of liquefied versions of gases such as nitrogen, oxygen, hydrogen and natural gas, among others. Cryocoolers provide the necessary cryogenic conditions to liquefy them.
From ships powered by liquid hydrogen to gas transportation and the many applications of liquid oxygen, the uses of liquefied gases obtained by cryogenic temperatures are increasing. Accordingly, the cryogenic equipment market is predicted to grow at a CAGR of 6.4% between 2020 and 2025, driven by Increasing demand for industrial gases and investments in LNG infrastructure, according to Markets and Markets.
- The military and space industry uses cryocoolers for many operations, including cooling infrared sensors in devices such as missile guidance systems or satellites
- The medical sector uses cryocoolers in MRI systems
- Superconducting electronics also employ cryocoolers
Different types of cryocoolers
As explained above, there are two main ways in which cryocoolers work (regenerative or recuperative systems). From those two chief working systems, a number of different types of cryocoolers have been developed:
- Heat exchangers
- Pulse tube cryocooler, which use sudden expansion and release of refrigerant gaseous substances
- Helium cryocooler
- Polycold cryocooler
- Stirling cryocooler, which consists of the following elements: a heat exchanger, a both a compression and expansion space, a piston, and a regenerator.
- Gifford – McMahon refrigerators. These are commonly used in MRI systems, and typically use helium as the working fluid.
- Joule – Thomson cryocoolers, which are also called Linde-Hampson coolers as they were invented by Carl von Linde and William Hampson. The sizes for this system can vary tremendously, from tiny to large scale, depending on their use. For instance, liquefied natural gas (LNG) will typically need a large scale system, which can employ multiple parts such as a compressor, a counterflow heat exchanger, a JT valve, and a reservoir.
The diverse types of cryocoolers speak of multiple possibilities in order to generate cryogenic temperatures needed for many purposes across different industries.
Are you searching for the right cryocoolers for your cryogenic equipment?
At Cryospain, we execute tailor-made cryogenic engineering systems, offering our expertise and know-how in order to generate cryogenic facilities and equipment projects, and guaranteeing efficient solutions tailored to the specific needs of our clients.
We also design and manufacture complete chassis and cryogenic equipment following the specific characteristics requested by our clients. As part of our designing process, we make sure all the system’s components are completely and compactly built in, thus allowing easy operations.
As part of these tailored cryogenic engineering infrastructures, we include the most adequate cryocoolers for each project when they’re needed or demanded.
Get in touch with us and learn more about our engineering solutions for cryogenic systems.