Beyond Familiar HFCs

DALLAS — While much of the buzz at the AHR Expo was on dwindling supplies of new HCFC-22, reclamation of that refrigerant, and use of alternative HFCs in retrofits, a number of conversations centered on alternatives beyond familiar HFCs. Even with the regulatory landscape unclear, the high global warming potential (GWP) of some HFCs was causing a stir on the show floor.

Low-GWP HFCs

While HFC-410A was firmly encamped as the refrigerant of choice for air conditioning in a large number of applications, its high GWP was turning attention in Dallas to use of HFC-32 as a stand-alone refrigerant. HFC-410A, which was introduced to the industry more than a decade ago as an alternative to R-22 in new equipment, carries a high GWP. R-32 has a much lower GWP (675 vs. 2088). This is a topic that has been in the industry for a number of years, since it first surfaced as a high-profile topic in 2010 at industry conferences hosted by Purdue University.

Danfoss furthered this notion at its AHR Expo booth, where it displayed its SG scroll compressor with the signage: “Get ready for Green Solutions with R-32.”

HFOs on Display

HFO refrigerants are widely recognized as the next generation of refrigerants. The alternative garnered its fair share of attention at the expo as well.

On the show floor, Honeywell was issuing a statement about its HFO refrigerant 1234ze which it markets as Solstice L-41. The manufacturer compared its refrigerant, stating that their refrigerant offers “significant advantages over another (R-410A) alternative, R-32, which has a higher GWP and limitations related to high-discharge temperatures, which can affect performance and durability in hot climates, and may also require new lubricants.”

Honeywell boasted that Solstice L-41 offers a 75 percent reduction in GWP compared to R-410A and is intended to replace R-410A in residential and light commercial air conditioning and heat pump applications. In addition to its lower GWP, Solstice L-41 offers excellent energy efficiency, is cost effective, and can be used in existing equipment designs with minimal changes.

“Honeywell has been working closely with leading equipment manufacturers to optimize Solstice L-41 to meet the demanding requirements of both stationary air conditioning and heat pump applications across a broad range of operating conditions,” said Tom Morris, director of commercial development for Honeywell Fluorine Products. “Solstice L-41 will allow these manufacturers to offer more environmentally friendly air conditioning and heat pump systems to help address climate change.”

Solstice L-41 is based on Honeywell’s HFO-1234ze technology, which was “first introduced in 2008 and has since been proven and commercialized for chillers, insulating-foam, and aerosol applications. A new HFO-1234ze manufacturing plant is currently under construction to meet the needs of equipment manufacturers.”

Even with its involvement with R-32 in some applications, Danfoss was waving the HFO flag. The company used a press conference to announce its involvement with HFO-1234ze in its Turbocor line and the commercialization of TG310 compressors, which were released as a developmental prototype in early 2012. The company said the compressors “utilize the ultra-low GWP, zero ozone depletion potential (ODP) refrigerant HFO-1234ze.”

Safety First

As the HFO sector evolves it is becoming clear that there are HFOs with A1 (nonflammable) safety ratings and those that have A2L (slightly flammable) safety ratings. A1s generally carry higher GWPs than A2Ls. This means the sector will have to sort itself out. If regulations set especially low GWP maximums, only A2Ls would be allowed to establish a beachhead; which would require UL certification, as well as building code modifications, for the installation of such equipment in certain portions of the country.

One HFO topic that appears to be sorting itself out is in the automotive sector. After automaker Daimler expressed some safety concerns over the use of HFO-1234yf in vehicle air conditioners last fall, General Motors issued a statement at the time of the expo pledging to move ahead with the use of that HFO in its vehicles — saying that in all its testing, the refrigerant proved safe and effective.

HCs and CO₂

A number of manufacturers showed equipment for natural refrigerants such as HCs and especially CO₂ at the expo.

During a Danfoss press briefing, Scott Martin, director of sustainable technologies, Hill Phoenix, spoke about CO₂ developments that his company has been doing in conjunction with Danfoss. He said that his company’s systems that utilize CO₂ technology offer several distinct advantages over traditional DX-refrigeration systems. “These CO₂ sub-critical systems deliver superior refrigeration performance with enhanced sustainability, reduced refrigerant-charge requirements, and greatly reduced refrigerant-leak rates. Simply, they are the most energy-efficient and environmentally friendly refrigeration systems available in the industry today.”

He also noted advances in CO₂ in transcritical-application use of which are growing in North America. That was reinforced on the show floor at the Bitzer booth where a transcritical-CO₂ compressor was displayed.

The editors of the European-based online publication R744.com also walked the floor at AHR and provided a viewpoint for its global readership regarding the future direction of CO₂ use in the United States.

“The pure number of booths displaying CO₂ refrigerant components and systems has not significantly increased from last year’s trade show. However, the showcase of breakthrough innovations, prototypes, and optimized product lines in R-744 (CO₂) compressors, heat pumps, or air conditioners, as well as commercialization announcements expected for the next 12 months are all solid indicators that the U.S. market is getting serious about R-744.”