Coolant Monitoring in Vehicles


Although we are well aware of the dreadful effects on the environment and the climate, turning up the AC when stuck in traffic on a hot day is extremely tempting.

With increasing awareness for the global warming potential (GWP) of many refrigerants, the previously used  R134a has been banned in new vehicles in the EU since 2017. Refrigerants for vehicles must have a GWP no greater than 150. As a reference: The GWP of R134a is 1430. R1234yf is now being used as a replacement, which is significantly more climate-friendly with a GWP of 4, but can still have devastating effects on the environment.

Refrigerants with Risk for Safety and Environment

R1234yf is a hydrofluoroolefin and belongs to the group of alkenes. They are the fourth generation of refrigerants and are intended to replace the climate-damaging fluorinated (chlorinated) hydrocarbons.

However, R1234yf and its decomposition product, trifluoroacetic acid, are difficult to degrade, especially when they contaminate groundwater. This cannot always be avoided in production and use. For example, leakage from refrigeration systems occur from time to time, even in vehicles. Additionally, the use of R1234yf can be problematic for safety reasons. Contact with hot surfaces can cause a fire in which R1234yf reacts to form corrosive hydrofluoric acid.

Reliable Measurement Technology for More Safety

A good alternative to fluorinated refrigerants is carbon dioxide (CO₂). With a GWP of 1, it is considered very climate-friendly and is neither flammable or toxic.



To date, however, it has rarely been used in air conditioning systems in vehicles. Although carbon dioxide is relatively inexpensive as a refrigerant, the technology for its use is quite costly. As a result, very few manufacturers have used this technology to date, and when they do, it is mainly in high-end vehicles. Regardless of the refrigerant used, leaks and outgassing into the vehicle compartment must be avoided, or at least detected quickly. CO₂ in particular has a significant impact on the driver's ability to concentrate, especially at concentrations higher than 1500 ppm. Fatigue and dizziness can also occur, increasing the risk of accidents. Reliable measurement technology is essential here. With non-dispersive infrared spectroscopy (NDIR) all common refrigerants can be detected. Even when switching to other refrigerants the measurement technology can be quickly adapted by selecting a suitable bandpass filter. Axetris infrared sources deliver high emission performance across the entire spectrum of approved refrigerants, providing the best basis for this measurement technology.