A new refrigerant for heavy duty mobile air conditioning systems?

Often times, technical developments in the European Union and on the automotive side find their way into the truck industry. That could very well be the case with motor vehicle air conditioning refrigerants.

The European Union (EU) has been a global leader in setting sustainability standards, including actions to fight climate change, says Joseph T. Martinko, global business and market manager, Opteon, for DuPont, a science-based products and services company founded in 1802 (www.dupont.com). In 2006, the EU adopted the Mobile Air Conditioning (MAC) Directive to reduce the climate impact of air conditioning in cars sold in the EU. 

Mobile air conditioning systems have been a dominating source of refrigerant emissions to the atmosphere.

Opteon is a family of lower Global Warming Potential (GWP) refrigerants developed by DuPont to enable automakers to comply with the EU’s MAC Directive. 

The MAC Directive requires that the air conditioning systems of all cars sold in EU Member States use an automotive refrigerant with a GWP of less than 150. The directive went into force on Jan. 1, 2013, to give automakers a number of years to identify a refrigerant that would comply, he explains, and industry members evaluated a range of candidates. 

The regulation allows for a phase-in period between 2013 and 2017. As of Jan. 1, 2013, only new model type cars sold in EU Member States must comply with the EU directive. By 2017, every new car sold in EU Member States must comply.

A CONSENSUS

“The consensus view was that HFO-1234yf is the most suitable alternative when considering all of the directive’s criteria,” Martinko says. “HFO-1234yf has been determined to have a GWP of less than 1. The automotive refrigerant that has been used for the last few decades, R-134a, has a GWP of 1,300.

In addition to its very low GWP, HFO-1234yf is energy efficient, which can help maximize the fuel efficiency of cars, further reducing the environmental footprint of cars over time, he adds.

DuPont and Honeywell – a Fortune 100 diversified technology and manufacturing company (www.honeywell.com) – worked together to develop HFO-1234yf. Today, the two companies are competitors selling this refrigerant separately as a near drop-in replacement for R-134a in motor vehicle conditioning applications. DuPont’s product is Opteon YF; Honeywell’s is Solstice yf.   

Refrigerant drop-ins are intended to replace the original refrigerant and keep the air conditioning system running in the same way. The U.S. EPA defines a “drop-in” as a substitute refrigerant that “provides exactly the same cooling, efficiency, durability and other performance factors as the original refrigerant, with no changes to existing equipment.”

Currently, there are no exact low GWP refrigerant drop-ins for R-134a.

U.S. REGULATIONS

There is no legislation in the U.S. requiring the use of a low GWP automotive refrigerant at present. However, the U.S. EPA has added HFO-1234yf as another alternative for motor vehicle air conditioning systems which automobile manufacturers may use.

This does not apply to the use of HFO-1234yf in the air conditioning or refrigeration systems of heavy duty trucks, refrigerated transport or off-road vehicles such as agricultural or construction equipment.

Industry experts expect that air conditioning systems for heavy trucks will be changed to HFO-1234yf or other refrigerants that have a lower GWP than the current R-134a.

“A number of automakers are using or moving to adopt HFO-1234yf for cars sold in the United States to take advantage of credits under the U.S. EPA tailpipe emissions standard that encourage the use of automotive air conditioning refrigerants with reduced climate impact,” says Dupont’s Martinko. ”Even without a regulation in place, these early action credits provide enough benefit to automakers that it is estimated that more than 50 percent of automobiles in the U.S. market will have converted to HFO-1234yf by 2018.”

DuPont does not expect that there would be a mandate requiring the use of a specific refrigerant. However, the U.S. EPA has announced that it intends to propose a regulation this summer that would remove R-134a from its list of accepted refrigerants for use in new vehicle air conditioning systems at some time in the next several years.

This past July 9, the Administrator of the U.S. EPA signed a proposed rule that, if finalized as proposed, would require all newly manufactured vehicles to use climate-friendly alternates to R-134a starting in model year 2021.

HFO-1234yf is one of three approved options and is being used in the United States already today, note agency officials. The other two are HFC-152a (R-152a) and R-744.

They say industry estimates are that there will be more than 2 million vehicles on the road in the U.S. using HFO-1234yf by the end of 2014.

CO2

Another refrigerant alternative to R-134a that is being adopted by some automobile OEMs is refrigerant-grade carbon dioxide (CO2), or R-744.

CO2 is not new to refrigeration. Its use began in the mid-19th century and steadily increased, reaching a peak in the early 20th century, according to the Linde Group, a world supplier of industrial, process and specialty gases (www.linde-gas.com).

Its use declined with the introduction of fluorocarbons chemicals that operated at much lower pressures. CO2 fell out of use by the 1950s.

Renewed attention to CO2 as a refrigerant came about with the increasing focus on environmental issues from fluorocarbon chemicals, which created a strong interest in systems using natural refrigerants.

R744 is environmentally friendly, having zero Ozone Depletion Potential (ODP) and minimal GWP, Linde officials say. Moreover, it offers some advantages, including non-flammability and low toxicity, plus has “excellent” thermodynamic properties and low energy usage.

The officials add that R744 is a high purity carbon dioxide-based refrigerant gas with a typical moisture content less than 10 parts per million. The low moisture content enables the refrigerant to work more effectively and it has less corrosive impact on refrigeration systems.

One major difference between R744 and other refrigerants is its pressure/temperature characteristic. Because of its high pressure and low critical temperature, refrigeration systems that use R744 require special equipment designs, along with safety features to guard against failures.

THE LAST TIME

The last time the industry went through an air conditioning refrigerant change was when it went from R-12 to R-134a, notes Robert Braswell, technical director of the Technology & Maintenance Council (TMC), North America’s premier technical society for truck equipment technology and maintenance professionals (www.truckline.com/Technology_Council.aspx). “That was in the early- and mid-1990s  when the coolant R-12, known as Freon, was linked to ozone depletion. Auto manufacturers were required to switch to R-134a by 1996.

Right now, it is not that big a deal for trucks, but it will be, he says. Nevertheless, now is the time to be cognizant of what’s going because HFO-1234yf and CO2 are very different refrigerants than R -134a.