Natural Refrigerants - Propane

Tuesday 7 April 2020

                                                NATURAL REFRIGERANTS - PROPANE

We at Stonegrove Refrigeration believe the industry has a responsibility towards the environment, when designing and installing refrigeration systems.  Because of this we continue to look at natural refrigerants and how they can help to tackle climate change and reduce the impact of our carbon footprint.  In a time when refrigerants are being closely evaluated for their environmental impacts, propane (R-290) is emerging as an increasingly viable alternative.

Propane’s use dates back to the early 1900s, when refrigeration systems relied solely on naturally occurring compounds (hydrocarbons) in the compression cycle.  It was a true “green” refrigerant, long before science had conceived of environmental problems such as ozone depletion and global warming, and is one of the cleanest and environmentally options available.  With a global warming potential (GWP) of 3 and an ozone depletion potential (ODP) of 0, propane poses virtually no threat to the environment.

Under the current F-Gas regulation a ban will come into effect in 2022; this will impact on new centralised refrigeration systems for commercial use with a capacity of 40kW or more, using refrigerant with a GWP of more than 150.  As this will rule out many of the refrigerants commonly used in chillers today, R-290 is an extremely good option.

Important and noteworthy characteristics

Performance efficiencies:  R-290 has excellent thermodynamic properties, high efficiency and high performance.  These include low back pressure, high volumetric capacity and coefficient of performance.  The performance characteristics are very similar to the now banned R22 and consistently outperforms R-404A in energy efficiencies.

Other comparable attributes:  When compared with the phased-out hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), propane has a lower system pressure drop and a higher heat transfer performance.  The refrigeration cycle coefficient of performance (COP) is comparatively good.  As a result, the refrigeration charge for propane can be significantly less than other common refrigerants

Additional benefits:

  • Readily available and affordable
  • The installation and commissioning process is much the same as for any chiller installation
  • Good compatibility with materials commonly used in the construction of refrigeration equipment
  • Very reliable
  • Safe to use when proper protocols are followed

Considerations:  There are some considerations that need to be made when using propane.  Like many hydrocarbons, propane is flammable - hence its ASHRAE rating of A3.  This can potentially have an impact on the refrigerant charge and, in turn, the size of the application.  This also means it isn’t suitable for retrofitting freon systems.  However, correct design, installation and maintenance means propane is safe to use.

Conclusion: With a zero ODP and a GWP of just 3 - along with proven excellent performances (particularly in comparison to some of the popular freon refrigerants) - it should be no surprise that R-290 is a viable natural refrigerant for both commercial and industrial applications.