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Understanding Applications for Alternative Refrigerants

jasonprenger Jason Prenger | Refrigeration Engineering Director

Emerson Commercial & Residential Solutions

Emerson’s tests* of leading alternative refrigerants suggest challenges as well as benefits. The full video details theoretical calculations and real-world tests.

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Emerson sees migration to lower-global warming potential (GWP) refrigerants as inevitable. Here are some challenges leading A1 alternatives may face, and how to potentially address them.

Heat of Compression

While new HFCs for R-404A offer a lower GWP, alternatives run significantly hotter in both low- and medium-temperature conditions. Compressor cooling will be needed in many low-temperature applications. This is potentially a big deal because some freezer applications can no longer run with non-liquid injected compressors. Full operating envelope capabilities are still possible with liquid injection, but this will likely require additional plumbing and power.

For low-pressure refrigerants, potential replacements for R-134A run at lower discharge temperatures, so there is less of a temperature concern. Our tests* have found the entire operating envelope for R-134A can be achieved with either 450A or 513A.

Capacity and Size

R-404A replacements typically deliver less capacity, especially in low-temperature applications, which will require larger compressors to match existing systems.

During our tests*, traditional HFC refrigerants like R-404A also had little or no temperature glide, so they didn’t affect system sizing. Emerging A1 replacements, however, have glide values of ~5 to ~8 °F. That potentially creates issues when calculating capacity that most of our industry hasn’t had to deal with in the past. Capacity at the midpoint in a medium-temperature system with R-404A, for example, isn’t much different from its dew point compressor rating. But an R-448A system would deliver 3 percent more capacity at the same conditions.

This is even more apparent in low-temperature systems. For example, if you’re sizing an R-448A system off dew point, you might expect capacity loss of 19.4 percent compared to R-404A. In reality, the system sees a drop of about 13.9 percent. While you’ll still have to increase the size of the compressor, using the midpoint can significantly affect your calculations.

In medium-temperature applications, the weighted Energy Efficiency Ratio (EER) of newer alternatives is similar to R-404A. In lower-temperature applications, there are trade-offs between efficiency and GWP. R-407A compares well with R-404A, but has a higher GWP than other alternatives. R-448A scores better on GWP, but requires more injection and power.

There’s little or no temperature glide in replacements for R-134A, but of the two main candidates, 513A meets or exceeds the capacity of R-134A, while 450A struggles in comparison.

Update on A2L/A3 Refrigerants

This presentation touched only briefly on A2L refrigerants, since they have yet to be listed as acceptable alternatives under the Environmental Protection Agency’s Significant New Alternatives Policy. However, Emerson continued testing functionality for A2Ls and the A3 R-290 throughout 2017. If you have any questions about these refrigerants, or want any evaluations done, please contact us to learn more about your options.

The full video details theoretical calculations and real-world tests.

*The results presented in this post are based on Emerson testing. Results may vary based on additional testing and application.

 

Latest E360 Webinar Explains Applications for New A1 Refrigerants

jasonprenger Jason Prenger | Refrigeration Engineering Director

Emerson Commercial & Residential Solutions

View our latest E360 webinar, “Understanding Applications for New Refrigerant Alternatives”.

Since the EPA’s 2015 rule that changed the listing status of certain hydrofluorocarbon (HFC) refrigerants to “unacceptable,” the commercial refrigeration industry has been closely evaluating new refrigerant alternatives. With a high global warming potential (GWP) of 3,922, R-404A was at the top of the list of those refrigerants scheduled for phase-out. Today, there are A1 refrigerants with GWPs below 1,500 that are available for use, such as R-448A and R-449A/B. But because they are largely unproven outside of manufacturer testing facilities, their reliability in specific applications is still in question.

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In our recent E360 webinar, I examined these new A1 refrigerants by comparing their performance characteristics and operating envelopes to R-404A and R-134a. Emerson has been testing these new A1s across our compressor platforms for several years. So, from an engineering perspective, we have compiled significant data to help the commercial refrigeration industry address these questions and evaluate this emerging class of refrigerants.

I reviewed the extensive process required to qualify compressors with new refrigerants and discussed several important considerations when using A1s:

  • R-404A alternatives have a higher heat of compression; R-134a alternatives have similar heat of compression
  • Liquid injection allows compressors to run at full low temperature operating envelopes for the R-404A alternatives, albeit with higher power consumption
  • Temperature glide is important to consider with R-404A alternatives

Per the first polling question posed in the webinar, nearly two-thirds of the audience is currently using or working with A1 replacement refrigerants. As I pointed out, some applications are more challenging to address with new A1s than others. For example, supermarket refrigeration systems have been trying non-R-404A options that are still allowable for many years, including R-407A and the natural refrigerant CO2. But, in medium-temperature, stand-alone units, the medium pressure A1 alternatives to R-404A — the R-407 series or lower GWP options like R-448A/R-449A — will either not be allowable or have yet to be listed by the EPA as acceptable for use. It’s also important to remember that these stand-alone applications are facing an EPA HFC phase-out date of Jan. 1, 2019 for the higher GWP refrigerants.

Aside from A1 alternatives, the industry is also evaluating A2L and A3 options, both of which fall into the flammable refrigerant classification. While the natural A3 refrigerant R-290 (propane) has gained acceptance by the EPA, many mildly flammable A2Ls are still going through the approval process. Both refrigerant types are the subject of numerous revisions to safety and building code standards.

Finally, I discussed the impacts of this transition to new refrigerant alternatives throughout the commercial refrigeration channel, from OEMs and wholesalers to contractors and end users; all will be impacted in one way or another over the coming years.

If you would like to view this webinar in its entirety, click here.

New Refrigeration Technology for walk-in beer keg coolers

The next time you are near Indianapolis, check out Sun King Brewery.  Emerson recently worked with Sun King Brewery (http://sunkingbrewing.com/) to fit new condensing units near the main entrance.  Since there wasn’t room to put the units in the back of the building, they needed quiet, reliable units that look good enough to be seen by visitors – and keep hundreds of barrels of beer fresh.  Read more about this case study

When you go, make sure that you sample their craft beers and take a brewery tour – and look for the new condensing units as you walk in.

Jason Prenger
Director – Refrigeration Engineering
Emerson Climate Technologies

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