Alternative refrigerants – modern solutions for freeze-drying

The shift toward future-proof refrigeration systems

Climate protection and new legal requirements are changing the world of cooling systems. Traditional refrigerants such as R404A, which have long been considered standard, are increasingly under regulatory pressure. The reason: They have a significant impact on the greenhouse effect. The GWP (global warming potential) value indicates the level at which a refrigerant contributes to the greenhouse effect compared to CO₂.

The F-Gas Regulation and international regulations are increasingly restricting the use of such substances. This poses a particular challenge for pharmaceutical production: Freeze dryers require very low temperatures in different areas of the plant, making the choice of refrigerant particularly challenging.

The industry is facing a radical shift from synthetic refrigerants and toward sustainable alternatives. But what options are available, and how do they differ?

Overview of alternative refrigerants

Liquid nitrogen (LN2)

This cooling system generates cold by evaporating nitrogen in heat exchangers, which transfer the cold without mixing the substances. The cooled silicone oil circulates and ensures even temperature distribution. Liquid nitrogen is a proven technology and particularly attractive for locations that already have a nitrogen supply, as it can be easily integrated into existing systems.

Advantages:

• Reliable
• Reduces electricity and water consumption at the machine

Disadvantages:

• Requires a storage tank
• Higher operating costs with frequent use

Air cooling

This technology compresses and expands air in a closed circuit. The process generates the necessary cooling without the use of additional refrigerants. Air systems are particularly suitable for ice condensers – the area where water vapor from the product settles as ice during drying. Very low temperatures are required here on a permanent basis. For other parts of the system, such as the storage areas which need to be cooled down quickly, the output alone is often not sufficient. In such cases, additional components such as boosters or buffer tanks are used.

Advantages:

• No use of synthetic or flammable refrigerants
• High efficiency at constant temperatures
• Future-proof technology

Disadvantages:

• Higher investment costs
• Less flexibility in dynamic processes

Natural refrigerants

These refrigerants do not contain any synthetic substances and are a long-term solution for freeze drying. They are used in special cascade systems that transfer the cold to the storage areas and the ice condenser via heat exchangers. Substances such as propane (R1270) and ethane (R170) are frequently used. They are powerful but flammable; requiring a well-thought-out safety concept. Modern systems use gas detectors and negative pressure areas to reliably control risks.

Advantages:

• Very low impact on the greenhouse effect
• Long-term availability and efficiency
• Suitable for storage areas and ice condensers

Disadvantages:

• Flammable, requiring additional safety measures
• Increased effort required for installation and monitoring

At Optima, cooling systems are individually tailored to your requirements. Depending on the project, solutions using liquid nitrogen, air cooling, or natural refrigerants are used –supplemented by safety features such as gas detectors and intelligent control systems.