Small But Mighty
Ultra-low temperature freezers, also called ULT freezers, are indispensable tools in modern laboratories, preserving critical biological samples at temperatures as low as -80°C. But how do these remarkable machines achieve such extreme cold? Here’s insight from LAF Tech, the leading laboratory equipment suppliers in Australia and New Zealand, including industry-leading ultra-low temperature laboratory freezers.
At the heart of an ULT freezer lies a refrigeration system. Similar to a household refrigerator, it employs a closed loop where a refrigerant circulates, undergoing a series of phase changes to transfer heat. However, the technology and components used in ULT freezers are far more sophisticated.
The Refrigeration Cycle
The process begins with a compressor, which compresses the gaseous refrigerant, raising its temperature and pressure. This hot, high-pressure gas then flows to the condenser, where it releases heat to the surrounding environment, typically through air cooling or water cooling. As the refrigerant cools, it condenses into a liquid state.
Next, the liquid refrigerant passes through an expansion valve, where it undergoes a rapid drop in pressure. This causes the refrigerant to evaporate rapidly, absorbing heat from the freezer’s interior and creating a cold environment. The now gaseous refrigerant returns to the compressor, and the cycle repeats.
Cascade Refrigeration
Achieving and maintaining temperatures as low as -80°C requires a more complex system than a single refrigeration cycle. This is where cascade refrigeration comes into play. This method employs two or more refrigeration cycles connected in series, with the evaporator of one cycle cooling the condenser of the next.
In a typical two-stage ULT freezer, the first stage cools the refrigerant to a moderate temperature, while the second stage uses this cooled refrigerant to achieve the ultra-low temperature required for sample storage. This multi-stage approach ensures efficient and reliable performance.
Insulation and Design
To prevent heat from entering the freezer and to maintain the extremely low temperature, ULT freezers incorporate high-quality insulation materials. These materials, often polyurethane or vacuum-insulated panels, create a thermal barrier between the freezer’s interior and the external environment.
The design of the freezer is also crucial. Features such as airtight doors, door seals, and even the placement of components within the cabinet contribute to maintaining the low temperature. Some ULT freezers also employ advanced features like temperature monitoring systems, alarms, and backup power options to protect valuable samples.
Challenges and Considerations
Operating ULT freezers presents unique challenges. The extreme cold can lead to wear and tear on components, requiring regular maintenance and calibration. Energy consumption is another significant factor, as these freezers operate continuously. Therefore, energy-efficient models with advanced features are becoming increasingly popular.
Moreover, the type of samples stored and the specific requirements of a laboratory will influence the choice of ULT freezer. Factors such as capacity, temperature uniformity, access, and recovery time should be considered when selecting a freezer.
As you can see, ultra-low temperature freezers are sophisticated pieces of equipment that rely on advanced refrigeration technology and careful design to preserve valuable biological samples. By understanding the basic principles of how these freezers work, researchers and laboratory personnel can make informed decisions about their equipment and ensure optimal sample storage.
Would you like to learn about specific features or buy ultra-low temperature freezers? LAF Technologies supplies ultra-low temperature laboratory freezers across Australia and New Zealand, including the IlShin +Series and DUO-Safe. Contact us today and work with the best laboratory equipment suppliers in Australasia.