Simple production technology for compact universal hydrogen tanks
Simple production process for tank modules made of carbon fiber-reinforced plastic (CFRP)
So far, large cylindrical hydrogen storage tanks have been used commonly; however, they require a great deal of space.Ā More compact tanks,Ā which can beĀ produced at low cost,Ā thereforeĀ play an important role in the development of fuel cell vehicles.Ā The research project Bryson, in which TU Dresden (Dresden Technical University), Hochschule MĆ¼nchen (Munich University) and Leichtbauzentrum Sachsen (Lightweight Construction Center Saxony) participate in addition to BMW, is looking for solutions to this problem.
Simple technology and low investment cost
We at BBG have developed aĀ simple process:Ā CFRP tank modules can be manufactured autonomously through the use of the self-closing molds developed and made by us.Ā This results inĀ low investment costĀ since the process doesĀ not requireĀ aĀ press or further production equipment,Ā such as autoclaves for curing.
Self-closing HP-RTM mold suffices for series production
During our production process, cylindrical hollow bodies, i.e. the inner shells of the cylinders, which are also referred to “liners”, are first overbraided with carbon fiber. Then the blanks thus prepared are inserted into the two-part mold. Up to 15 cylinders with a diameter of 50 mm and more can be produced simultaneously per operation.
A low-viscosity, resin-based mixture is then injected into the heated mold under a high level of pressure. This mixture penetrates the carbon-fiber braid, enclosing the individual fibers evenly and without defects in the process. After curing in the mold, the modular CFRP cylinders can be removed and connected to form a tank.
Compact tanks, range similar to those of internal-combustion engines
SinceĀ tanks are assembled from individual CFRP cylinder modules, they can beĀ tailored precisely to the installation space available in a vehicle. The modules can be integrated, for example,Ā in the floor assembly to save space. Such a tank filled with 700 bar internal pressure facilitates aĀ rangeĀ that isĀ similar to those offered by internal-combustion enginesĀ for hydrogen-powered passenger and commercial vehicles.
Efficient and reliable production of hydrogen tank
The mold concept for modular hydrogen tanks is based onĀ our comprehensive expertise in the high-pressure resin transfer molding (HP-RTM) process,Ā as we have developed and manufactured molds for this process for many years. In 2019, we presented aĀ mold for the production of hydrogen tanksĀ at the JEC World Composite trade show.
Gerhard Hƶrtrich, our project manager, likes to refer to our large competence in tool and mold making: “Since theĀ high pressureĀ applied to hydrogen tanks requires aĀ great deal of component stability, we attach particular importance toĀ maximum precision in the design and production of HP-RTM molds.
For theĀ production of the hydrogen tanks to be as efficient as possibleĀ at the same time, we have developed and integrated a reliable sealing system, among other things. This system ensures thatĀ virtually no manual reworking is requiredĀ after the resin mixture is injected”, says Hƶrtrich.