TECHNOLOGY FOCUS
Curing the Refrigerant BluesFRANKFURT, GERMANY (Sept. 17, 2007) - As automakers struggle to meet upcoming air-conditioning refrigerant emissions legislation, Delphi Corp. is developing several options that fulfill the new regulations and are also suitable for a wide range of climates and cost
structures. Heating, ventilation and air-conditioning (HVAC) systems contribute to global warming because of their energy usage during operation and by refrigerant leakage into the atmosphere. The climate impact of the refrigerant itself is defined as its Global Warming Potential (GWP). In 2006, the European Union banned the use of refrigerants with a GWP that is greater than 150 for all new Type-Approvals (new vehicle platforms) from 2011 and for all new vehicles as of 2017. The current refrigerant, R-134a, has a GWP of
1,430.
Choices, choices, choices ... Delphi is currently developing several options below the 150 GWP level, including R-744, R-152a and refrigerant blends to help automakers meet the legislation in a way that is both cost-effective for automakers and drivers in the global community. "Delphi has a long history with developing HVAC systems for alternative refrigerants," says James Giardino, general director of engineering, Delphi Thermal Systems.
R-744 Carbon dioxide, formally known as R-744, when used as a refrigerant, virtually eliminates the global warming effect of refrigerant leakage, but its advantage is reduced in higher ambient climate conditions because of its lower energy efficiency. Therefore, R-744 may be a solution for Central and Northern Europe, but would be difficult to adopt in areas such as the southern United States, the Middle East, and the equatorial regions of the world. Additionally, R-744's inherently high pressure requires redesign of major HVAC system components, adding significant costs and presenting some safety concerns requiring
resolution.
R-152a Delphi is also currently working with the United States Environmental Protection Agency (EPA) and a number of OEMs to demonstrate the value of its R-152a system to a global
audience. R-152a, commonly used as an aerosol propellant for hair sprays, shaving creams, baby care products, dusting sprays and spray paints, offers comparable climate performance to R-744. R-152a is currently produced in China, Japan and the United States. Major current R-134a thermal system components can be used with R-152a, making the switch to R-152a a less-costly conversion from an industry investment point of view. Additionally, R-152a systems use proven technology and have been shown to provide similar comfort and performance as an R-134a
system. A key concern with R-152a to date, however, has been its mild flammability, which Delphi believes could be safely considered with the application of secondary loop technology. Of note, Delphi's system keeps the R-152a entirely under the hood and away from the passenger compartment. "Delphi's secondary loop system, coupled with its system controller, can provide a 13 to 19 percent reduction in fuel usage by the air-conditioning system," says Giardino. "This is a valuable energy savings."
New hybrid blends Additionally, a third set of options now exists. New refrigerant hybrid blends - mixtures of two or more refrigerants, including newly invented materials - have been recently proposed and are currently under study by automakers. Although potentially useful, these refrigerants create the need to consider production-readiness timing and require exploration of safety, environment, stability and durability characteristics. Delphi continues to work closely with the global automotive industry to fully investigate the potential use of these new refrigerant
blends. "We believe that too many uncertainties exist, at the present time, to get consensus on a single solution for the global market," says Giardino. He adds that environmental impact, costs, service readiness, reliability and safety are just a few reasons why a global switch to just one alternative refrigerant may not be possible right now. "Delphi's goal is to offer a range of possible viable refrigerant solutions to global automakers to meet the European legislation," he explains. "More than a decade ago, we led the industry through the migration from CFC-12 (Freon) to R-134a. We're actively engaged in helping our OEM customers and the industry identify and implement the best solution
possible."
(Source: Delphi Corp.) 
