E360 Outlook: Making Sense of Natural Refrigerants
Natural refrigerants such as CO2 are gaining wider adoption in commercial refrigeration systems thanks to their lower global warming potential (GWP), safety and training, capacity and energy, Life Cycle Climate Performance (LCCP), and compliance with upcoming regulations. Here are some key considerations for end users looking at future system architecture choices.
European F-Gas regulation changes will have global impact
On January 1, 2015, Europe will begin phasing out high GWP refrigerants, and the U.S. isn’t far behind. This will have several effects on commercial and domestic refrigeration markets:
- 2015: New equipment bans in domestic refrigerators and freezers — refrigerants limited to 150 GWP
- January 2020: Service and maintenance ban on all H7==88888FC refrigerants exceeding 2,500 GWP
- Also in 2020: Refrigerants limited to 2,500 GWP in new commercial hermetically sealed systems — dropping to 150 GWP in 2022 (though F-gasses with GWP less than 1,500 may be used in the primary refrigerant circuit of a cascade system)
The rest of the world is watching Europe seriously, because as equipment gets designed it gets pulled through other global regions.
Europe’s New F-Gas Phase-Down and Bans Go Into Effect January 1, 2015
Regulatory changes proposed in the U.S.
The U.S., Canada and Mexico are presenting the North American amendment to the Montreal Protocol this summer, and the U.S. EPA has announced two rule-making changes affecting new equipment:
- Approve new lower-GWP fluids.
- Change status of R404A in multiplex supermarket refrigeration systems. R404A systems reaching a GWP level of 3,922 and R410A with around 2,000 GWP are in use today.
As we look to the future and reducing GWP of gasses, the option that’s essentially future-proof is to move to mildly flammable refrigerants.
Secondary, cascade and transcritical CO2 systems
R744 (CO2), first used in the 1920s before other synthetics were invented, is a high-pressure refrigerant with zero ODP and a GWP of 1. It is non-toxic, non-flammable, odorless, and heavier than air. Smaller line sizes are used because of its lower viscosity, and CO2 is less sensitive to pressure drops. CO2 is cost-effective, and depending on environment and system design, can perform better than HFCs.
Cascade subcritical CO2 and secondary systems (liquid recirculation) are usually used in high ambient areas such as southern Europe, mid-to-southern U.S., and much of central South America, Asia, Africa and Australia. The high side of a CO2 secondary system can either be ammonia or HFCs. In a cascade system, the low stage provides the cooling load and uses CO2.
Transcritical systems are usually used in areas where the ambient temperature is generally below 25 °C/ 77 °F, such as northern Europe, Canada, and northern U.S. New designs are improving efficiency in warmer climates. A CO2 booster system using transcritical compressors can work in transcritical or subcritical range.
Colder climates clearly lead the world in CO2 transcritical refrigeration systems, with close to 70 system installations in supermarkets in North America expected by the end of 2014, and more than 2,885 already in northern Europe.
Map of CO2 Transcritical and CO2 Cascade/Secondary Stores Worldwide in 2013
In the next installment of Climate Conversions, I’ll cover other natural refrigerant alternatives currently under consideration. Watch for it in the next few weeks.
Director of CO2 Business Development
Emerson Climate Technologies