The refrigerant regulatory landscape is changing in the U.S., leaving supermarket owners and operators scrambling to figure out which lower-GWP solution(s) will work best for their specific application. This is particularly the case in California, which is proposing a GWP limit of 150 for new stationary refrigeration systems containing more than 50 pounds of refrigerant, starting on Jan. 1, 2022.

Outside of California, some grocers will likely stick with their legacy HFC (or even HCFC) refrigerants until they are forced to make a change, either through new regulatory mandates or a significant rise in the price of their refrigerant. Many others, however, are looking for ways to incorporate more environmentally friendly solutions, such as HFO blends or “natural refrigerants” such as CO₂, ammonia, and R-290. Given that the latter option requires purchasing all new equipment, many grocers are taking a closer look at retrofitting their equipment with HFO blends.

Natural Refrigerants

In comparing so-called natural refrigerants with HFO blends, it is important to understand that “natural refrigerant” is a marketing term, said Jordan Smith, executive director of globalFACT, a non-profit group that promotes reduced-GWP solutions. He added that these products are industrial chemicals and undergo intensive processing in order to be brought to refrigerant specifications.

“Hydrocarbons such as propane, butane, and pentane are produced in oil refineries by ‘cracking’ fossil fuels and separating out various byproducts through distillation,” he said. “Carbon dioxide is brought to refrigerant specifications by industrial processing. While ammonia can be produced naturally by decomposition of animal waste, most of the ammonia used industrially is produced by a chemical process and is, in fact, synthetic.”

HFO blends are particularly appealing to grocers, noted Smith, because they can be retrofitted easily and affordably into existing refrigeration systems. Switching to ammonia or CO₂ requires investing in all new refrigeration architecture, some of which can be much more complex than existing systems.

“Retrofitting is often the most energy-efficient and cost-effective option to allow end users to move more quickly to products that meet regulatory requirements and limit environmental impact without large direct and indirect costs,” he said. “The greater complexity of so-called naturals like ammonia or CO₂ can drive up cost and require longer downtime for retailers, which has a direct impact on their bottom line.”

That is why grocers looking to select an alternative refrigerant for their commercial refrigeration systems should consider a number of critical factors, including performance (capacity and energy efficiency), sustainability, safety, and total cost of ownership (capital, energy, maintenance, training, etc.), said Chuck Allgood, PhD, refrigerants technology leader at Chemours (see sidebar).

“While it’s difficult to simply compare refrigerants on an ‘apples to apples’ basis since system design is such a critical factor, in general, HFO-based refrigerants perform quite well in terms of capacity and energy efficiency,” he said. “In some cases, ammonia and hydrocarbons may have high theoretical efficiency but are very limited in applications due to the safety concerns that either limit charge size (flammability risks) or locations and applications (toxicity risks).”

Ammonia systems also tend to have a very high capital and maintenance costs, said Chris LaPietra, vice president and general manager of Honeywell Stationary Refrigerants. As for CO₂ systems, they, too, can have high maintenance costs due to complexity, as well as reliability issues. They also tend to consume more energy, particularly in warm ambient temperatures.

“While there are appropriate applications for industrial gas solutions like propane and ammonia, these solutions can pose risks in certain applications and be more costly to install and maintain due to higher pressures and higher risks if leaks occur (e.g., toxicity/flammability of ammonia, high flammability of hydrocarbons, and the high operating pressures of CO₂),” he said. “Fluorinated refrigerants, which were originally developed to combat these risks, have lower (or no) flammability and are nontoxic, and offer good efficiency over a wide range of temperatures. Fluorinated refrigerants also provide a broad range of capacity and pressures, which allow for their safe and economically viable use in applications where propane and ammonia and other industrial gas solutions are not the safest or economically the best option.”

Honeywell Options

One of the HFO blends supermarket owners will likely consider is Honeywell’s Solstice N40 (R-448A), which is a nonflammable replacement refrigerant for legacy HFCs and HCFCs such as R-404A and R-22. (See Table 1.) This HFO blend offers a GWP that is approximately 68 percent lower than legacy HFC refrigerants such as R-404A and also consumes less energy.

Table 1. HFO refrigerants offered by Honeywell

“Compared to R-404A, Solstice N40 has demonstrated an average of between 5 to 15 percent lower energy consumption in refrigeration applications in U.S. and European supermarket trials,” said LaPietra. “It can be used in new installations, as well as retrofitted into existing systems that use high-GWP refrigerants such as R-404A and R-507.”

It is important to note that refrigerants can only be retrofitted if they have identical ASHRAE classifications, he added. For example, to retrofit a R-404A system, another A1 solution such as R-448A must be used. (Honeywell’s extensive retrofit guide, including a step-by-step checklist, can be found at www.fluorineproducts-honeywell.com/refrigerants/resources.)

Honeywell also offers Solstice L40X (R-455A), which is designed to replace R-404A. It is a mildly flammable, zeotropic refrigerant with an ultra-low GWP of 146 that can be used in commercial refrigeration applications, including plug-in cabinets, condensing units, mono-blocks for cold and freezer rooms, heat pumps, and chillers, subject to use restrictions. When integrated into appropriate system architectures, Solstice L40X provides end users with a long-term, cost-effective refrigeration solution, said LaPietra.

Given California’s proposed GWP limit of 150 in some stationary refrigerant equipment, Honeywell is continuing to look for more efficient non-flammable refrigerants that meet these stringent regulations. In fact, the company has just received a provisional ASHRAE number for a medium-pressure, <150 GWP, A1 refrigerant.

“R-471A is a blend similar to R-134a with low glide suitable for medium-temperature refrigeration applications or for use on the top end of a cascade system,” said LaPietra. “As a non-flammable solution, it gives refrigerator manufacturers more options where <150 GWP is a requirement. We expect to see some innovative system architectures to accommodate this refrigerant.”

Chemours Options

Chemours offers a wide range of Opteon™ low-GWP refrigerant alternatives that can also be used in commercial refrigeration, see Table 2. One of their most popular HFO blends, Opteon XP40 (R-449A) is designed to replace R-22, R-507, and R-404A in existing equipment and has a GWP nearly 70 percent lower than that of R-404A.

Table 2. HFO refrigerants offered by Chemours

“In general, the performance match for HFO blends like XP10 (R-513A) and XP40 (R-449A) versus their incumbents is quite good, since these blends were optimized to match performance and serve a critical need as retrofit refrigerants with minimal cost,” said Allgood. “Many thousands of R-22/R-404A/R-507 systems have been successfully converted to R-449A globally and continue to perform quite well, usually showing reduced energy usage post conversion.”

SUCCESSFUL CONVERSION: Many thousands of R-22/R-404A/R-507 systems have been successfully converted to R-449A globally and continue to perform quite well, according to Chemours.

Converting to an HFO blend is a fairly straightforward process, with only a few critical items to consider, said Allgood. These include:

• R-22 retrofits should ensure lubricant (to POE) and elastomeric seal change outs (just like R-407A); and
• R-404A retrofits should consider compressor OEM guidance for discharge temperature management and thermostatic expansion valve (TXV) adjustments/sensing element changes. (Chemours’ detailed retrofit guidelines and case studies are available at www.opteon.com.)

As pressure grows from states such as California to transition to very low GWP (<150) alternatives in new commercial refrigeration equipment, there will be a shift to a range of new refrigerants.

“There are some <150 GWP pure HFOs (e.g., R-1234yf) and blends (e.g., R-454C) that provide excellent performance and can help end users meet California’s low GWP proposal if desired,” said Allgood. “Since most of these ultra-low GWP refrigerants in commercial refrigeration are A2Ls, they need to be used per the appropriate safety standards and building codes. However, systems using the very low GWP HFO blends have already been installed in Europe and are performing quite well.”

Supermarket owners looking to either comply with new refrigerant regulations or just become more environmentally friendly may find that HFO blends solve both issues. These lower-GWP refrigerants offer comparable energy efficiency and, most importantly, can be retrofitted into existing systems, which grocers will likely find very appealing.