- Статьи
- Science and technology
- Tank or otherwise: scientists have come up with a way to rid airplanes of fuel tanks
Tank or otherwise: scientists have come up with a way to rid airplanes of fuel tanks
Scientists have proposed a new material for the safe storage of hydrogen, an environmentally friendly fuel of the future. The development makes it possible to solve the problem of explosion hazard and may open up new opportunities for "hydrogen aviation". In particular, the new technology will potentially allow the abandonment of traditional fuel tanks in airplanes. Their function can be performed by structural elements — for example, wing and fuselage parts, capable of acting as a storage of energy-intensive substances and actually "soaked" with hydrogen. Experts note that scientists' calculations require experimental verification, which will allow us to assess whether the development can be applied in real aircraft systems.
Where and how can fuel hydrogen be stored
Planes of the future may lose their fuel tanks — other structural elements will fully or partially take over their function. This solution was proposed by scientists from the National Research Nuclear University MEPhI.
Researchers have developed a new material for storing hydrogen, a promising environmentally friendly fuel. The substance is able to easily absorb gas when it is supplied, and when the pressure decreases or heats up, it releases it back. This opens up the possibility of using aircraft structural elements, such as the wing or fuselage, as fuel storage.
The specific heat of combustion (energy value) of hydrogen is almost three times higher than that of jet fuel. At the same time, in hydrogen fuel cells, the reaction product is water, which makes carbon an environmentally friendly alternative to traditional energy sources. However, the introduction of such technologies is hindered by the high explosive risk of gas, as well as the difficulties associated with its storage and transportation.
— We have proposed a two—dimensional lithium carbide crystal. It is a flat lattice (one atom thick) where carbon atoms are surrounded by lithium atoms. Tests have shown that hydrogen molecules adhere to the crystal not too weakly so as not to volatilize, and not too strongly so that they can then be used as fuel," Professor Konstantin Katin, head of the Laboratory of 2D Nanomaterials in Electronics, Photonics and Spintronics at the National Research Nuclear University MEPhI, told Izvestia.
According to him, the main advantage of the material is its low weight. At the same time, 1 kg of the substance is capable of accumulating 60-80 g of hydrogen. For comparison, high-pressure cylinders can store about 40-50 g of gas per 1 kg of the system. According to expert estimates, materials in which the proportion of retained hydrogen exceeds 5% of its own mass are considered promising.
— The material works like Velcro. Lithium atoms have free orbitals that accept electrons from hydrogen. As a result, there is a weak electrical connection. The advantage of the system is that hydrogen comes out of the "trap" at a temperature close to room temperature, explained Konstantin Katin.
Calculations have shown that at a pressure of 10-20 atmospheres and a normal temperature, lithium carbide retains almost all of the hydrogen, but if the pressure is lowered, it releases. Such parameters are ideal for storage, as they do not require additional equipment to maintain the necessary conditions. That is, in order for the hydrogen to be released, you just need to lower the pressure, open the "valve".
— In the future, the material may become promising for hydrogen aviation, where every kilogram counts. Such an aircraft will not need heavy batteries or thick—walled steel cylinders — a light sheet that holds hydrogen like a sponge is enough," the developer said.
At the same time, the mechanical properties of the material are still limited, the scientist noted. Therefore, it is unlikely to be suitable for power structural elements, but it can be used, for example, as a filler for sandwich panels used in the cladding of aircraft and space technology.
How technology will save jet fuel
Engineers have yet to learn how to synthesize lithium carbide on an industrial scale and embed it in composites, Konstantin Katin added. But the main thing is that the theoretical barrier has been overcome, and the creation of an aircraft that carries fuel not in tanks, but in structural elements, has become a technical task. These and similar issues will be discussed at Space Week, which will be held on April 6-12.
— Solid—state hydrogen storage is one of the promising areas. Unlike high-pressure cylinders, such systems are safer and more technologically advanced. The lack of such solutions hinders the development of hydrogen transport," Vadim Popkov, head of the Laboratory of Materials and Processes of Hydrogen Energy at the A.F. Ioffe Institute of Physics and Technology, Associate Professor of the Department of Physical Chemistry at St. Petersburg State Electrotechnical University LETI, told Izvestia.
In aviation, it is especially important how much energy can be stored per unit mass of a system — this is relevant for both small drones and large aircraft, he noted. However, other parameters are also important.: the rate of hydrogen release, the temperature ranges of operation, the resistance of materials to vibrations and loads. Therefore, the computational and theoretical results require experimental verification, which will allow us to assess how such developments can be implemented in real aviation systems.
— The proposed systems may look like cryogenic tanks with lithium carbide inside in the form of powder or granules. Their advantages are lower weight. And this means saving fuel, increasing flight range or payload," said Karina Krylova, senior researcher at the Institute of Problems of Superplasticity of Metals of the Russian Academy of Sciences.
Scientists have shown that the material has the highest hydrogen absorption energy. However, it has a number of disadvantages: for example, the absorption energy decreases with an increase in the mass fraction of absorbed hydrogen, she added. To solve the problem, porous composite materials based on lithium carbide can be created, or these sheets can be alloyed with heavier metals, but the latter will increase the mass of the hydrogen carrier, which will make it difficult to use the system.
Problems may also be related to the high chemical activity of lithium and hydrogen-based materials. In particular, hydrogen is capable of causing embrittlement of metals, said Alexander Rodygin, project manager of the laboratory "Hybrid and Electric Power Plants" at the Advanced Engineering School of the Moscow Aviation Institute.
In addition, when using lithium carbide in powder form, there may be risks of material degradation during filling in the container. The issues of synthesis, storage and transportation of substances, as well as the total cost of such systems, remain important. The idea looks interesting, but it is still far from practical implementation, the specialist concluded.
Переведено сервисом «Яндекс Переводчик»
