Low GWP

The ongoing Low-GWP AREP is testing 38 potentially low GWP refrigerants that could be used as alternatives instead of higher GWP refrigerants. “These refrigerants represent what the industry currently feels have great potential to replace HCFC-22, R-134a, R-404a, and R-410A,” said AHRI’s Xudong Wang, who presented the paper at Purdue.

Noting the phaseout of R-22 by 2040 in developing countries and 2030 in developed countries, Wang said HFCs such as R-410A and R-134a “have come under close scrutiny due to global warming concerns.”

For the paper, five familiar and commonly used refrigerants — R-134a, R-404A, R-410A, R-22, and HFC-407C — were set as “baseline refrigerants.” Then testing and evaluation of the newer refrigerants was conducted to compare with each of the baseline refrigerants.

Some of the new refrigerants are being tested with more than one of the baseline refrigerants, others with just one of the baseline. They span the gamut of familiar refrigerants (such as R-32, ammonia, and propane) to some of the newer HFOs such as 1234yf (already being used in automotive air conditioning in Europe) to experimental developmental refrigerants from several refrigerant manufacturers.

And the refrigerants stretch across the board from those with the A1 safety rating, the A2L slightly flammable rating, and A3 flammable.

As noted by Karim Amrane, AHRI vice president, regulatory and research, “This is a cooperative research program to identify suitable alternatives to high GWP refrigerants. This research is strongly desired by OEMs to access research needs, accelerate the industry’s response to environmental challenges, and avoid duplicate work.”

While the AHRI paper deals with such aspects, Wang noted, “The performance of air conditioning and refrigeration systems using these candidates needs to be evaluated to ensure acceptable system capacity and efficiency.”

Cost Effectiveness

According to Rajan Rajendran, vice president of engineering services and sustainability for Emerson Climate Technologies, the issue of efficiency was one reason that prompted the LCCP project.

“New synthetic lower GWP refrigerants and natural candidates are options for air conditioning, heat pump, and refrigeration applications,” he said.

But he noted during the presentation at the FMI conference, “A Life Cycle Climate Performance approach to system design and refrigerant choice adopts a holistic approach to refrigerant selection factoring in safety, environment, performance and total costs.”

Rajendran made the FMI presentation with Michael Saunders, director, end user technical sales and support.

One of the matrixes shown to an audience of supermarket engineers detailed “emerging lower GWP refrigerants for new and existing applications.” Many of those were the same ones in the AHRI study.

The LCCP study looked at three categories of current applications: unitary a/c, commercial a/c, small chillers; refrigeration; and large chillers and mobile refrigeration. The grid then plugged in “new LGWP refrigerants for OEM use,” such as the HFOs and developmental refrigerants that would be used in new rather than retrofit applications. In addition, developmental synthetic refrigerants for existing applications were looked at. Also looked at were what the study referred to as “today’s refrigerants,” such as those in the R-400 series (including -404A, -407A, -407C, -407F, and -410A).

Rajendran encouraged the store engineers as well as contractors to “minimize LCCP with options available today to meet your needs.” He noted, “Many lower GWP synthetic candidates will soon become commercially available. These candidates target keeping performance the same and reducing GWP and LCCP.”

He added, “Natural refrigerants like NH3 (ammonia), CO2, and R-290 (propane) should be considered when they make sense.” He noted that “regulations, safety, economics and performance have to favor choice over all alternatives.”

Among specific findings:

• There are alternatives to R-404A including R-407A and R-407F “that give good performance overall with lower GWP and lower LCCP.”

• The traditional air conditioning refrigerant R-410A is a “good option in medium temperature (refrigeration) and acceptable in low temperature applications with system redesign.”

• Options are available for R-22 stores needing conversion. Cited were “R-407A, R-407C, 407F, R-438a, etc.”

Even as the industry works on future refrigerants, Rajendran said that “many benefits can be achieved now with existing technologies.” He said these include “a focus on energy efficiency improvement, maintenance, and refrigerant containment.”

Publication date: 10/29/2012