In the context of climate change, the legal regulations on the use of climate-damaging refrigerants are being increasingly tightened worldwide. This has led to a sharp price increase for less harmful refrigerants. The temptation to mix harmful and climate-friendly refrigerants in order to save costs is strong. Refrigerant detection sensors can help to monitor the strict regulations for the use of climate-damaging gases. Fraunhofer IPM develops cost-effective, precise, compact and reliable refrigerant detectors.
Photoacoustic gas detection in a gas measuring cell
Our gas sensors for refrigerant detection are based on the photoacoustic effect. A photoacoustic gas sensor consists of a broadband, modulated infrared light source, a gas-measuring cell containing the test gas sample and a microphone. For precise gas detection, commercially available MEMS microphones are used. If the gas in the measuring cell absorbs the light rays, the gas sample in the sensor volume heats up. This temperature rise in turn leads to a pressure increase, which the microphone will detect.
A photoacoustic NDIR measurement technique developed at Fraunhofer IPM allows us to analyze the exact composition of a mixture of different refrigerants, including 2,3,3,3-tetrafluoropropene (R1234yf) and 1,1,1,2-tetrafluoroethane (R134a). This could e.g. prevent garages from illegally filling air-conditioning systems in cars with prohibited mixtures. Due to the simple measuring principle, the measuring system can be used in stationary, miniaturized and mobile applications.