Is DR-55 best option to replace R410A?

USA: Chemours has unveiled further details of a new refrigerant blend to rival R32 in the search for a lower GWP alternative to R410A in air conditioning systems.

According to Chemours, the new gas, DR-55, has a very similar GWP to R32 but with better efficiency, lower discharge temperatures and a lower flammability.

In tests, DR-55 also exhibited better performance than both R410A and R32 when used as a drop-in in an R410A system.

Chemours unveiled the new refrigerant at the 2015 International Congress of Refrigeration (ICR2015) in Yokohama, Japan, last month. The conference also featured a Trane AquaTrine demonstration chiller using the new gas.

Chemistry

Seen by Chemours as a replacement for R410A in direct expansion air conditioning, heat pump and chiller applications, the Cooling Post has learned that the chemistry behind DR-55 shares a commonality of constituents with R410A, R32 and other potential lower GWP R410A replacements.

Led by Daikin, R32 is currently being promoted by most of the Japanese manufacturers as the alternative to R410A in new, small split systems. R32 had previously been considered when chemists were first looking for a replacement for R22 in the late 80s, but, at the time, its flammability, albeit very low, was considered unacceptable. The flammability suppressant R125 was ultimately added in a 50/50 mix to create R410A.

With the current drive towards lower GWP refrigerants, however, a degree of flammability has come to be considered inevitable to meet HFC phase-down targets. In addition, soon to be altered standards will allow A2L refrigerants to be used in larger systems.

Alternatives under development

A number of potential R410A replacements are currently under test from the major refrigerant producers. Most appear to mix R32 with an HFO. Honeywell has been toying with blends of R32 and the HFOs 1234ze and 1234yf. Chemours, itself, has DR-5A, designated by ASHRAE as R454B, a 68.9%/31.1% blend of R32 and 1234yf. DR-55 seems to be a further development of that, reducing the amount of yf and adding R125 in a blend formulated as 67% R32, 7% R125 and 26% R1234yf. In layman’s terms, if you like, DR-55 is a form of  R410A with added R1234yf.

Despite the availability of DR-5A, Chemours sees DR-55, which it will market as Opteon XL55, as a preferred low GWP replacement for R410A in new equipment “As it offers the highest levels of performance without compromise,” the company says.

“XL55 [DR-55] delivers improved energy efficiency, 67% GWP reduction as compared to R410A, ultra-low flammability properties, excellent performance at high ambient temperatures, and easy conversion from existing R410A designs due to very close physical properties,” it adds.

Flammability

As well as offering lower discharge temperatures than R32, tests are said to have shown that DR-55 also exhibits a slower burning velocity and higher minimum ignition energy requirement when compared to R32.

Although DR-55 has the same A2L “mildly flammable” classification as R32, Chemours maintains that some global OEMs have indicated that the lower flammability properties of XL55 are compelling and are likely to be an important consideration in product selection, especially for larger charge size equipment. 

“The selection of a lower GWP replacement refrigerant by OEMs typically involves a consideration of a variety of factors, including performance, safety, environmental impact and total cost of ownership, and we believe XL55 will perform well against these broad considerations,” a Chemours spokesperson said.

Drop-in test

At the ICR conference, Joshua Hughes, Chemours r&d leader for air conditioning and heat pumps, reported on a drop-in test that was carried out in a Chemours r&d laboratory in Wilmington, Delaware. In the test, a 2.5 ton (8.8 kW) York residential ducted split air conditioning/heat pump system was converted from R410A to DR-55 with no system or lubricant changes. DR-55 delivered nearly 5% improvement in energy efficiency at equivalent cooling capacity. In addition, discharge temperatures were similar to R410A.

“Opteon XL55 enables new equipment manufacturers to move away from R410A to a lower GWP solution at the lowest transition cost, highest energy performance, and lowest 2L flammability,” said Diego Boeri, global business director, Chemours Fluoroproducts. 

Work is underway to submit XL55 for ASHRAE classification in December. Chemours says it is preparing for a high level of interest in this product when, pending regulatory approvals, it becomes commercially available next year.

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