Always good quality when refueling with hydrogen, no impurities that damage the fuel cell: Professor Andreas Schütze and his research team from Saarland University are working with partners to develop a sensor system that constantly monitors the quality and purity of hydrogen directly at the fuel pump.
The infrared measuring cell should withstand the most adverse conditions in the tank line: it should reliably measure despite extremely high pressure and fast refueling. In autumn, the system goes to a gas station in trial operation.
If the quality and purity of the fuel do not agree, that is bad for the car. This also applies to fuel cell vehicles. Although the driver fuels hydrogen here, but also can be contaminated. During production, on the way to the filling station as well as during pressing into the tanks, sulfur components, ammonia or hydrocarbons can enter the hydrogen. And that also spoils the driving pleasure. “It can lead to a poisoning of the fuel cell,” explains sensor expert Andreas Schütze of the University of Saarland. Already with small impurities the cell membranes can be damaged. The fuel cell produces less power, less power and fewer miles on the road. If the going gets tough, the car will endure permanent damage.
To prevent this from happening, Schütze and his team are developing a process with partners to ensure that the fuel cell has good fuel and thus the hydrogen car has a long service life. Involved are the Fraunhofer Institute for Solar Energy Systems ISE and the company Hydac Electronic.
Up to now, hydrogen has been extensively and selectively investigated through random sampling and analysis in laboratories. At the University of Saarland and at the Saarbrücken Center for Mechatronics and Automation Technology (Zema), the researchers are working on a sensor system that monitors hydrogen quality permanently while refueling. “The challenges here are on the one hand in the required accuracy and on the other in the conditions under which the measuring system should measure,” says Sagittarius: Concentrated 700 to 900 bar pressure leave the tank needle after less than three minutes at the stop.
The researchers are therefore developing an infrared measuring cell that works reliably and accurately even under these extreme conditions. They even use the high pressure to further increase the sensitivity of their process. Andreas Schütze and his team have already brought such measuring cells to market for oil and liquids. But here the researchers enter new territory. “So far there is no experience with measurements at such high pressure. Normally such measurements take place at a pressure of at most 40 or 50 bar, “says Andreas Schütze. The measuring cell for the odorless gas is placed directly in the tank line: The hydrogen flows through a tube. “Here we scan the gas with an infrared source and catch the rays on the opposite side. If the gas changes chemically, also changes the received light spectrum. From this we can draw conclusions about admixtures and impurities, “explains Andreas Schütze.
Researchers are currently conducting experiments and assigning measurements to the various contaminants. They work out which wavelengths of infrared light are best suited and calibrate their system. This is preliminary work for the sensor system, which is to be put into trial operation this fall for the first time in the petrol pump of a petrol station. “We are investigating whether and how the measured values of the infrared spectrum change depending on the pressure. The system must reliably detect very different impurities, which are also significantly lower than, for example, with oil, “explains engineer Marco Schott, who works as a doctoral student at the hydrogen measuring cell.
The Federal Ministry of Economics is funding the project with around two and a half million euros.
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