Hydrofluorocarbon (HFC) R-404A has been used for many years as a long-term refrigerant replacement blend for chlorofluorocarbon (CFC) R-502. R-502 was a binary, azeotropic refrigerant blend of hydrochlorofluorocarbon (HCFC) R-22 and CFC-115 with an ASHRAE safety classification of A1.
Because R-502 was a 500-series blend, it had negligible temperature glide and fractionation potential. R-502 was a popular medium- and low-temperature refrigerant because it could operate in positive pressures at very low evaporator temperatures. Even in applications with evaporator temperatures of minus 40°F, R-502 could operate out of a vacuum on the low side of the system. Electric Driven Ac Compressor
Low compression ratios were also seen in systems using R-502, giving it much better volumetric efficiencies and improved capacities than its competitor R-12 in those days. R-502 was first manufactured in 1961; however, in 1996, there was a production ban on R-502 and all other CFC refrigerants because of the environmental concerns of ozone depletion and global warming.
R-404A was intended to be used as a medium- and low-temperature, commercial, long-term replacement for CFC-502. R-404A is a near-azeotropic, ternary refrigerant blend consisting of HFC-125 (44 percent), HFC-143a (52 percent), and HFC-134a (4 percent). R-404A is a 400-series refrigerant blend with a small temperature glide, which has the potential to fractionate.
R-404A systems use a polyolester lubricant. R-404A is being used by OEMs in new equipment and also on retrofitted equipment. However, because of its high global-warming potential (GWP), the U.S. Environmental Protection Agency (EPA), under its Significant New Alternatives Policy (SNAP) program, has listed R-404A as an “unacceptable” refrigerant in a number of retail food refrigeration categories and in the vending machines end-uses listed here:
Although R-404A consists of a mixture of three HFC refrigerants and has an ozone depletion potential (ODP) of zero, it does have a GWP of 3,922, according to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, 2007. A GWP of 3,922 means R-404A traps 3,922 times as much heat per kilogram as carbon dioxide does over a 100-year period of time.
HFC refrigerants are rapidly accumulating in the atmosphere, and as they accumulate, they change the balance between the energy entering the earth’s climate from the sun and the energy escaping the earth back into space. HFC-134a, which makes up a small part (4 percent) of the blend R-404A, has had an atmospheric concentration increase of about 10 percent per year from 2006 to 2012. Also, the concentrations of HFC-143a and HFC-125, which are components of R-404A and many other commonly used refrigerant blends presently in use today in HVACR equipment, had annual atmospheric concentration rises of 13-16 percent, respectively, from 2007 to 2011. Even though HFCs represent a small fraction of the current greenhouse gas emissions by weight, their warming impact per kilogram is very strong.
The majority of HFC use in the U.S. and globally is in the refrigeration and air conditioning sector, and their emissions are projected to increase substantially and at an increasing rate over the next several decades if their production is left uncontrolled.
Globally, HFC emissions are increasing 10-15 percent annually. In fact, emissions are projected to double by 2020 and triple by 2030. Without action, annual global emissions of HFCs are projected to rise from 6,400 to 9,900 million metric tons of carbon dioxide equivalent (MMTCO2eq) in 2050.
Here is a look at some options available to contractors as we move beyond R-404A.
R-449B — R-449B is a nonflammable, non-ozone depleting (ODP = 0) replacement for R-404A with a low GWP of 1,296. R-449B is a four-part refrigerant blend of HFC-32, HFC-125, HFC-134a, and HFO-1234yf. It has an A1 safety classification, meaning it is nonflammable and nontoxic. Existing polyolester lubricants used with R-404A can also be successfully used with R-449B. SNAP has listed R-449B as an acceptable refrigerant for use in:
Testing has shown that R-449B (R-404A replacement and retrofit) can offer up to an 11 percent efficiency increase over R-404A while cutting the GWP by two-thirds.
R-449A — R-449A is a SNAP-listed four-part refrigerant blend of HFC-32, HFC-125, HFO-1234yf, and HFC-134a. It has an ODP of zero. R-449A is an HFO-based refrigerant blend designed to replace R-404A in stationary refrigeration applications. It combines excellent cooling performance and energy efficiencies with a low-GWP value of 1,397. Also, existing polyolester lubricants used with R-404A can also be successfully used with R-449A. It is designed for use in new and retrofitted direct-expansion, low- and medium-temperature commercial and industrial applications.
R-448A — R-448A is a nonflammable, nontoxic, class A1, five-part refrigerant blend. It has the same component refrigerants as R-449A with the addition of a small amount (7 percent) of HFO-1234ze. It is an R-404A replacement refrigerant with an ODP of zero and a low GWP of 1,273.
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John Tomczyk is HVACR professor emeritus, Ferris State University, Big Rapids, Michigan, and coauthor of Refrigeration & Air Conditioning Technology, published by Cengage Learning. Contact him at tomczykjohn@gmail.com.
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