Mercedes-Benz to begin equipping top models with CO2 air conditioning systems starting in 2017; adapting other models for R1234yf
From 2017, Mercedes-Benz will offer in Europe the S- and E-Class as the first production passenger cars equipped with CO2 air conditioning systems. These completely newly developed systems are based on the DIN specifications defined by the automotive standards committee of the German Association of the Automotive Industry (VDA).
Due to especially quickly available and high cooling performance, CO2 air conditioning systems swiftly provide for a pleasant feel-good climate inside vehicles even in very hot weather, the company said, while at the same time complying with legal requirements for low global warming potential refrigerants and avoiding the use of R1234yf, which Mercedes has found problematic. (Earlier post.)
The EU is mandating a limit of 150 for the global warming potential (GWP) index of refrigerants used in mobile air conditioning systems. Apart from CO2, R1234yf is the only refrigerant produced on an industrial scale to date with which the future requirements of the EU directive for air conditioning systems in new vehicles can be met.
The current dominant refrigerant R134a has a GWP of 1,300; the sanctioned low GWP replacement refrigerant R1234yf has a GWP of 4; and R744 (CO2) of 1. The Mercedes solution thus offers an even lower impact on the climate than R1234yf, while avoiding the in-use issues Daimler identified back in 2012.
The use of CO2 as a refrigerant necessitates the redesign of crucial components. CO2 air conditioning systems operate at a pressure of more than 100 bar—some ten times higher than that of today’s systems. This means that all components including the hoses and seals need to be redesigned.
Mercedes-Benz has drafted corresponding standards together with all German automobile manufacturers and numerous suppliers in the automotive standards committee of the German Association of the Automotive Industry (VDA). The publicly accessible DIN specification documents also offer other companies an opportunity to quickly launch development activities of their own. This would create the prerequisites for swift market penetration by this high-tech air conditioning system, the company suggests.
Mercedes-Benz has assumed a pioneering role in this respect. It is the first automobile manufacturer to award not only development contracts but also to place production orders for CO2 air conditioning systems and their components.
Adapting other models for R1234yf. Despite the exceptionally short time frame, the high level of quality targeted by Mercedes-Benz for CO2 air conditioning systems has already been realized in the new development for the company’s top models.
However, deployment throughout the entire vehicle fleet will not be feasible by the effective date of the new EU directive on 1 January 2017. To also meet the EU requirements on schedule for all other model series, the company has developed safe and reliable solutions for the use of R1234yf
The R1234yf refrigerant has different flammability properties than the R134a refrigerant used in the industry to date. In order to ensure a continued high standard of safety for its customers in the future, Mercedes-Benz has carried out extensive testing on all its vehicle models.
The result is a comprehensive package of vehicle-specific measures in order to guarantee Mercedes-Benz’ high safety standards for the models using the R1234yf refrigerant.
In particular, these include a specially developed protective system tailored to the given vehicle configuration. In the event of a severe frontal collision, the patent-pending system ensures that the resultant refrigerant/air mixture is separated from the hot engine components in the engine compartment and that these components are furthermore cooled in a highly effective manner.
This is made possible by a gas generator, which releases inert argon gas specifically at the relevant hot spots. This effectively keeps the mixture from bursting into flames.
As a result, this solution ensures that customers’ justifiable safety needs and Mercedes-Benz’s high safety standards will continue to be met in the future. At the same time, it also provides the company with another means of helping to protect the climate.