Co-authors​ :

 Thomas VINAY NAGARAJ (GERMANY), Thomas VINAY NAGARAJ , Thomas VINAY NAGARAJ  

Fiber-reinforced plastic pressure vessels with a plastic liner to ensure sufficient resistance to H2 permeation (so-called Type 4 tanks) are cur-rently state-of-the-art for hydrogen storage. Carbon fibers (C-fibers) are applied in a winding process to the preformed liner for the load-bearing structure of the vessel. Common winding processes are efficient and suitable for industrial use but are significantly limited in terms of geo-metric freedoms. Due to the mandatory winding angle, it is not readily possible to apply purely axial fiber layers. Also, vessels with a diameter smaller than approximately 200 mm cannot be manufactured in a pro-duction-ready process, as the winding angle deviates significantly from the geodesic path, and the domed area disproportionately thickens due to frequent winding around a small area. For commercial vehicle tech-nology, the use of purely axial fiber reinforcement has the potential to utilize the pressure vessel additionally as a structural element (e.g., out-rigger, spar). This is precisely where the presented research project comes in. In a novel manufacturing process, cylindrical pressure vessels are realized with fibers applied purely axially and in the circumferential direction, possessing maximum lightweight construction quality and can be manufactured very thinly in diameter. The transmission of the load from the axial layers in the cylindrical region of the pressure vessel is done layer by layer using the "IVW force introduction," patented by IVW. This integrates the metallic domed areas in a load-appropriate manner. In contrast to the state of the art, where a preformed "plastic bladder" is used, a metal or plastic tube can be used as a liner, which can be easily varied in geometry (especially length changes). A first de-sign variant could not achieve the burst pressure of 157.5 MPa required for an operating pressure of 70 MPa due to a leak in the overlap area from the liner to the domed area. Therefore, the design was fundamen-tally revised to generate higher tension of the circumferential layers and increase the compression between the liner and the domed area. This is achieved through a conical clamping element (patent pending) on the inside (see figure 1). Additionally, an O-ring increases the seal. First prototypes were manu-factured and subjected to a burst test, reaching values up to 160.6 MPa. The utilization of the slim tanks is achieved through the "interconnec-tion" of multiple containers into a conformable tank (see figure 2). In this configuration, a so-called master tank, equipped with a refueling valve (OTV), supplies additional connected containers that can be ar-ranged arbitrarily. This allows for the utilization of very shallow spaces (e.g., in the underbody or under the cargo area) or compact rectangular spaces (e.g., behind the driver's cabin) with optimal use of space for hydrogen storage.