Typical applications for refrigeration:
- Domestic & residential: air conditioners and household refrigerators.
- Commercial: retail, grocery, and hospitality cooling systems.
- Industrial: large-scale applications like petrochemical plants, food processing, brewing, and fruit storage.
- Healthcare & pharmaceuticals: medical storage and cryogenic freezing.
- Transport & logistics: cold chain systems for shipping and trucking.
Types of refrigerants:
Synthetic Refrigerants
- As the name suggests it is not naturally occurring
- Also known as “freons”
- High GWP (Global Warming Potential)
- Typically found in supermarkets, home fridge and your car’s AC
- Not well regulated within the industry with very adherence by installers to SANS guidelines for safe and responsible usage and construction
When to use what?
We need to base our decision on the following factors:
- Cost (Capital outlay and life cycle costs such as maintenance, efficiency etc.)
- Safety and the environment
- Location and footprint constraints
When to use what?
Synthetic Refrigerants
Cost
- Relatively cheap, mass produced and catalogue based
- Fair COP (Coefficient Of Performance) but not the best
- Can be expensive to maintain (components are typically replaced and not repaired)
Safety and the environment
- Not very environmentally friendly and toxic to humans (undetectable to the nose and kills by depriving oxygen)
Location and foot
- print constraintsIdeal for small applications (commercial etc.)
When to use what?
Cost
- Custom-built systems, typically viable above 100 kW.
- High efficiency (COP) when correctly designed.
Maintenance
- NH₃: Lower cost, robust and repairable components.
- CO₂: Higher cost, components usually replaced rather than repaired.
Safety & Environment
- Both are environmentally friendly.
- Both are hazardous to humans; CO₂ is harder to detect.
Application / Footprint
- Best suited for medium to large commercial and industrial systems.
When to use what?
- CO₂ has high volumetric cooling capacity, enabling smaller pipes and components than NH₃.
- NH₃ systems usually have higher upfront costs due to larger equipment requirements.
- CO₂ becomes inefficient above its low critical point (31°C), while NH₃ has a much higher critical point (132°C).
- Climate matters: South African summers often approach CO₂’s critical limit, while cooler European climates are more favourable.
- CO₂ operates at much higher pressures than NH₃ (up to ~6× higher).
- NH₃ systems are heavily regulated and over-engineered for safety.
- CO₂ systems are often built like standard freon systems, raising safety and reliability concerns.
Conclusion
Refrigeration systems are long term investments
- Maintenance and running costs (reliability, durability, efficiency)
- Life cycle costs are crucial and electricity a premium in SA
- We operate in warmer ambient temps compared to Northern Europe so NH3 is much more efficient for South African temperatures.
- For product temperatures up to -25°C use NH3 if you can. Only if we go below this then CO2 becomes worth investigating.
- For fruit processing and storage requiring minimal electricity and lowest possible life cycle costs then use NH3
- CO2 requires superheat which means lower suction pressures resulting in higher risk of fruit moisture loss meaning less weight per fruit. NH3 requires no superheat so we can run higher suction temperatures mitigating the risk of moisture loss in fruit completely.