2. Cryogenic measurement technology supporting the development of hydrogen-powered aircraft
Electric propulsion is not feasible for large commercial airplanes in the short and medium term because the batteries and wiring would be too heavy. Not to mention that these batteries would generate a lot of heat and offer short service life in terms of the number of flight hours of a jet airliner. Instead, hydrogen-powered aircraft is one of the most promising technologies for large commercial aviation. When generated from renewable energy sources, it emits zero CO2. Significantly, it delivers approximately three times the energy per unit mass of conventional kerosine fuel and more than 100 times that of lithium-ion batteries.
3D rendering of zero-emission aircraft with two hybrid-hydrogen turbofan engines
However, storing hydrogen onboard an aircraft poses several challenges. A growing number of aircraft companies are working on cryogenic hydrogen tank designs, as cryotank storage is considered one of the best options for its storage. Hydrogen turns into a liquid when cooled to a temperature below -253 °C (-423 °F). The properties of liquid hydrogen enable significant increases in density over high-pressure gas storage, as well as reduced tank mass due to lower pressure operation, but does impose some significant operational constraints on the fuel system:
- It requires an airtight insulation system to reduce the boil-off of the liquid hydrogen and maintain it at cryogenic temperatures.
- Liquid hydrogen handling requires specialized equipment and procedures.
- The fuel tanks must be maintained at a constant pressure to minimize boil-off.
- Liquid hydrogen tanks and lines must be sealed off from the atmosphere (if air enters the tanks, it will freeze solid and can block the flow lines).
The range of Q.series X A105 CR measurement modules has been designed for use with cryogenic temperature sensors, like Cernox® or TVO. The module provides ultralow sensor excitation to minimize measurement error due to the sensor self-heating while maintaining a good signal-to-noise ratio. Furthermore, the module comes with a sensor-specific linearization table to compensate for the high non-linearity of cryogenic temperature sensors.
In addition, a variant of our renowned A101 measurement module has been introduced for measuring strain in a low-temperature environment. The module comes with smart ON/OFF switching of the bridge excitation voltage to avoid sensor self-heating and a 3-step measurement to correct the influence of thermoelectric voltage when using cryogenic wiring.