Among the next generation of refrigerants with low-global warming potential (GWP), the natural refrigerant R-290 (aka propane) has already established a niche in commercial refrigeration. As evolving safety standards lay the foundation for higher charge limits of flammable refrigerants, R-290 is expected to play an expanded role in the coming years. In the last installment of our Journey to Lower-GWP Refrigerants E360 Webinar series, Justin Miles, Emerson’s account executive, and I discussed the drivers supporting the continued adoption of R-290 and provided an overview of its refrigerant characteristics and application considerations.
As one of the low-GWP refrigerant alternatives approved by the Environmental Protection Agency’s (EPA) Significant New Alternatives Policy (SNAP) rules, R-290 has been commonly used in lower-capacity, stand-alone equipment such as small reach-in display cases, beverage coolers, ice machines and ice cream freezers. Its GWP of 3, small charge limit of 150g and energy-efficient performance have made R-290 a logical choice for foodservice operators and food retailers embarking on the transition to lower-GWP refrigeration.
Path to higher charge limits and growing application potential
R-290’s classification as an A3 “higher flammability” refrigerant has limited its use to smaller refrigeration applications and mandated a maximum charge limit of 150g. Recent updates to the Underwriters Laboratories (UL) safety standard UL-2-89-60335 second edition have increased R-290 charges in self-contained applications. These revised charge limits are calculated according to R-290’s lower flammability limit (LFL) and the type of self-contained application (with or without doors or drawers), and must pass the revised standard’s Annex CC test for “adjacent appliances” when the charge limit exceeds 150g of flammable refrigerant:
- 8 x LFL for closed cases (300g for A3)
- 13 x LFL for open cases (500g for A3)
It’s important to remember that the updated UL-2-89-60335 safety standard is just the first of many steps that must take place before higher charges of R-290 can be implemented in the U.S. Over the next few years, we expect the following necessary regulatory and code updates to follow suit:
- EPA SNAP revision for higher R-290 charges
- Model code updates in the upcoming code revision cycle
- State and local building code updates
Ultimately, higher charges of R-290 will enable increased capacities in self-contained systems, larger refrigeration loads and even an expanded application potential (e.g., self-contained, walk-in units).
Performance characteristics and safety considerations
In the webinar, Justin explained how R-290 compares to legacy hydrofluorocarbon (HFC) refrigerants in terms of energy efficiency and other key performance benchmarks. Emerson’s test labs have demonstrated its relative efficiency advantages using a Copeland™ scroll compressor in a variety of conditions, including low-temperature (LT), medium-temperature (MT) and extended MT scenarios. In each condition, R-290 delivered significant energy efficiency ratio (EER) improvements over its HFC predecessors — offering nearly 7 percent gains in LT and more than 12 percent gains in MT and extended MT conditions.
In a real-world ice machine application, the original equipment manufacturer (OEM) Leer compared system performance and efficiency using both R-290 and R-404A. Per their findings, R-290 delivered an improvement of more than 20 percent in relative coefficient of performance (COP), providing lower high-side operating pressures and higher thermal conductivity. These proven energy efficiencies make R-290 an attractive option for OEMs seeking to meet ever-tightening standards set forth by the Department of Energy (DOE) on commercial refrigeration equipment.
From both safety and servicing perspectives, Justin explained that the industry has developed an ever-expanding pool of resources to help technicians familiarize themselves with best practices and even achieve R-290 certifications, such as those from the Refrigeration Service Engineers Society (RSES.org). Generally, flammable refrigerants will require leak detection; and technicians should eliminate the potential for exposing the refrigerant to open flames during servicing. Compressors and refrigerant bottles must be clearly labeled to identity the type of refrigerant and its potential flammability.
By following proper safety guidelines for design and servicing — many of which are already in place due to R-290’s existing footprint in commercial refrigeration — R-290 will continue to be a safe, reliable and efficient low-GWP refrigerant alternative.
To learn more about the expanding business case for R-290, please view our webinar, Applying R-290 in Commercial Refrigeration Applications, which concludes our Journey to Lower-GWP Refrigerants E360 Webinar series. Whether you’re an owner/operator, OEM, contractor or design consultant, we wish you the best on your refrigerant transition and hope you continue to review these webinars as needed.
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