As the world shifts to embrace the use of hydrogen fuel as a clean source of energy, the production of affordable, durable and efficient hydrogen tanks has offered a research area of interest within the transportation and energy industries. As used in fuel cell vehicles, hydrogen-powered aircraft, they are meant to store and transport hydrogen under cryogenic conditions at minus 253 degree C.
Nevertheless, its behavior as a liquid causes problems for manufacturing when compared with gaseous hydrogen that the industry can supply, it also demands highly specialized materials, engineering processes, and quality control. This article aims to identify major challenges which the manufacturers encounter when manufacturing liquid hydrogen tanks.
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Unbelievable low temperature conditions
Some of the most challenging characteristics when manufacturing tanks for the storage of liquid hydrogen are the systems that enable the container to remain at cryogenic conditions. Hydrogen becomes a liquid at -253°C and preserving it at this temperature among lesser losses in heat is another problem completely. The tanks requires high end insulation systems which will hold up when exposed to such conditions. Conventional insulation approaches fail, and trustworthy manufacturers use Multiple Layer Insulation (MLI) and Vacuum Insulation (VI) systems to reduce heat escaping. Even the tiniest of imperfections in insulation results in the quick vaporization of the liquid hydrogen, fuel waste in addition to safety issues.
Choice of Material and their suitability
The selection of material is very important when dealing with liquid hydrogen. Since most of them undergo a transition in phase behavior at cryogenic temperatures, metals are prone to fractures and leakages at such temperatures. Thus, it becomes necessary for the manufacturers to incorporate, the special alloys or composites that are out there, because they are very rigid, ductile and strong even in low temperatures.
Some of the types of advanced composites materials used include aluminum-lithium alloys and carbon fiber reinforced plastic (CFRP) and these have certain drawbacks including; high cost and difficult to manufacture. Another challenge is to make sure that these materials can cope with what is known as thermal cycling – cycles of heating and cooling due to the process of tank filling and emptying.
Weight optimization
As most engineers know in the field of aerodynamics and astronautics, weight is a valuable commodity. Conventional tanks of liquid hydrogen may prove to be massive owing to the fact that constituent walls of the tank have to be thick in order to contain the cryogenic state of the substance and also protect it from leakage. Current innovations in the manufacturing of tanks are aimed at the development of a slim line car audio subwoofer that is manufactured from carbon composite and geometrical structures. But losing weight without losing stiffness is a very fine line that requires serious engineering capability. Also, the components made of lightweight material are relatively more prone to damages which make the process of handling as well as assembling them during production a bit challenging.
Sustainable manufacturing operations
A liquid hydrogen tank construction requires intricate processing technologies such as filament winding, automated fiber placement, and welding. All these processes have to be performed with a high level of precision, which is why even the minimal defect of the tank’s surface can negatively affect the process. Welding specifically proves quite problematic because conventional approaches cause microcracks or residual stresses which damages the structure. Such techniques as Friction Stir Welding (FSW) are applied, but their application is rather effective bringing an additional contribution to the manufacturing costs due to the use of high-performance equipment and particular skills.
Control of quality and safety
It is especially important to protect tanks with liquid hydrogen because hydrogen is highly flammable and working with very low temperatures. Purchasers have to maintain strict criteria in quality control, including non-destructive tests including ultrasonic testing, X ray testing and cryogenic pressure testing. Each part is examined for the presence of cracks, leak paths, and other material defects while every connection weld must be tested to guarantee it could not fail at the wrong moment. Applying these measures of quality control causes a lot of time and money to be spent, thereby adding to the complexity of the production process.