Composite overwrapped pressure vessel

Abstract

A composite overwrapped pressure vessel, comprising a mandrel 800; a composite laminate (140, figure 9) wrapped over the mandrel; at least one boss 120, 130, arranged to enable fluid ingress and egress; wherein the mandrel comprises: a hollow casing enclosing a cavity for storing fluid; wherein the casing is nonsealing for fluid stored in the pressure vessel when in use.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a composite overwrapped pressure vessel, in particular a composite overwrapped pressure vessel for storing a fluid, such as hydrogen, for use as a fuel in automotive vehicles, watercraft and aircraft. The present disclosure also relates to automotive vehicles, watercraft and aircraft comprising a composite overwrapped pressure vessel. BACKGROUND

[0002] Composite overwrapped pressure vessels are vessels designed to hold a fluid under pressure. Typically they comprise a liner wrapped with a fibre composite. The function of the liner is to seal the fluid and provide a barrier between the fluid and the composite, and the function of the fibre composite is to provide the structural strength necessary to hold the fluid under pressure.

[0003] Composite overwrapped pressure vessels have been developed to reduce weight and improve efficiency of storage of pressurised fluid. This has led to the development of different types of pressure vessels, which range from pressure vessels with no composite material to a completely composite structure. The different types are:

[0004] Type 1: an all metal construction, the metal providing both the sealing and structural strength;

[0005] Type 2: a metal liner with some composite overwrap, typically in the hoop direction. The metal and the composite overwrap share the structural loading;

[0006] Type 3: a metal liner with a full composite overwrap. The composite overwrap carries the structural load;

[0007] Type 4: a polymer liner with a full composite overwrap. The composite overwrap carries the structural load;

[0008] Type 5: a liner-less, all-composite design, which provides both the sealing and structural strength. BRIEF SUMMARY OF THE DISCLOSURE

[0009] Aspects and embodiments of the invention provide a composite overwrapped pressure vessel, an automotive vehicle comprising a composite overwrapped pressure vessel, a watercraft comprising a composite overwrapped pressure vessel and an aircraft comprising a composite overwrapped pressure vessel.

[0010] In accordance with the present disclosure there is provided a composite overwrapped pressure vessel comprising: a mandrel; a composite laminate wrapped over the mandrel; at least one boss arranged to enable fluid ingress and egress; wherein the mandrel comprises: a hollow casing enclosing a cavity for storing fluid; wherein the casing is non-sealing for fluid stored in the pressure vessel when in use.

[0011] In some examples, the hollow casing comprises at least one wall.

[0012] In some examples, the at least one wall comprises a gas permeable material.

[0013] In some examples, the at least one wall comprises perforations.

[0014] In some examples, the hollow casing comprises a first end and a second end, wherein the at least one wall spans between the first end and the second end.

[0015] In some examples, the at least one wall, the first end and the second end are integral.

[0016] In some examples, the at least one wall is joined to the first end and the second end.

[0017] In some examples the at least one of the first end and the second end comprises at least one mating surface and the at least one wall comprises one or more corresponding mating surfaces for joining the at least one wall to the first end and / or the second end.

[0018] In some examples at least one of the first end and the second end comprises a boss interface which integrates the first end or second end with one of the at least one boss.

[0019] In some examples the at least one wall comprises an extruded profile.

[0020] In some examples the hollow casing comprises one or more ribs secured to or within the at least one wall.

[0021] In some examples, the at least one wall is tubular.

[0022] In some examples, the first end and the second end are hemispherical.

[0023] In some examples, the hollow casing comprises a first end, a second end, a framework spanning between the first end and the second end, wherein the composite is wrapped over the first end, the second end and the framework.

[0024] In some examples the framework comprises a plurality of beams, each of the plurality of beams extending between the first end and the second end, wherein the composite is wrapped over and contacts the plurality of beams.

[0025] In some examples the framework comprises a plurality of tensioned flexible rods, each of the plurality of tensioned flexible rods extending between the first end and the second end, wherein the composite is wrapped over and contacts the plurality of tensioned flexible rods.

[0026] In some examples the composite overwrapped pressure vessel additionally comprises a tensioning bar, extending within the cavity and attached to the first end and second end, wherein the tensioning bar tensions the plurality of tensioned flexible rods.

[0027] In some examples, the plurality of tensioned flexible rods extend in a substantially parallel direction to a direction in which the tensioning bar extends.

[0028] In some examples, the plurality of tensioned flexible rods extend in a direction offset by an angle to a direction in which the tensioning bar extends.

[0029] In some examples the framework comprises a lattice.

[0030] In some examples the lattice is a single integral structure.

[0031] In an aspect according to the invention there is provided an automotive vehicle comprising at least one composite overwrapped pressure vessel as described in any preceding paragraph.

[0032] In an aspect according to the invention there is provided a watercraft comprising at least one composite overwrapped pressure vessel as described in any preceding paragraph.

[0033] In an aspect according to the invention there is provided an aircraft comprising at least one composite overwrapped pressure vessel as described in any preceding paragraph. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 shows a composite overwrapped pressure vessel according to examples disclosed herein; Figure 2 shows a cross-section through a composite overwrapped pressure vessel according to examples disclosed herein; Figure 3 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 4 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 5 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 6 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 7 shows a cross-section through a composite overwrapped pressure vessel according to examples disclosed herein; Figure 8 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 9 shows a cross-section through a composite overwrapped pressure vessel according to examples disclosed herein; Figure 10 shows part of a composite overwrapped pressure vessel according to examples disclosed herein; Figure 11 shows a cross-section through a composite overwrapped pressure vessel according to examples disclosed herein; Figure 12 shows an automotive vehicle comprising a composite overwrapped pressure vessel according to examples disclosed herein; Figure 13 shows a watercraft comprising a composite overwrapped pressure vessel according to examples disclosed herein; Figure 14 shows an aircraft comprising a composite overwrapped pressure vessel according to examples disclosed herein. DETAILED DESCRIPTION

[0035] Composite pressure vessels can be used to store high pressure fluid for use as fuel in a vehicle, such as a hydrogen fuel cell vehicle. For example, compressed hydrogen is stored in the pressure vessel until it is needed. When hydrogen is required, hydrogen gas is released from the storage tanks and injected into the fuel stack. Electrochemical reactions in the fuel cell stack result in the production of an electric current which can power an electric motor.

[0036] Fuel cell vehicles, hydrogen combustion vehicles and other developing or future technologies which require the storage of compressed hydrogen are envisaged to become increasingly in demand as the world shifts towards low-carbon / zero emission transport. Whilst battery electric vehicles (BEVs) have seen a surge in popularity and development to provide zero emission transport, they have significant drawbacks which make them an unappealing option as a full-scale replacement of hydrocarbon internal combustion engines. For example, BEVs have a comparatively low energy density, which has a dramatic effect on efficiency when scaled up for use on heavy goods vehicles (HGVs), ships and aircraft. The weight and size of batteries required in such applications makes battery technology a currently unfeasible option. The weight and size of the batteries would not only compromise the effective range of the vehicles, but would also compromise cargo capacity. Additionally, the mining of Lithium and other minerals is becoming increasingly difficult as demand increases, as well as causing a significant amount of carbon emissions in its extraction and shipping around the world.

[0037] Hydrogen as a fuel provides a comparatively higher energy density which can solve the problem of zero-emission solutions for such large vehicles.

[0038] Challenges in storing hydrogen include maximising the capacity of pressure vessels and reducing their weight, all whilst still providing the necessary strength for storing the hydrogen and protection from external forces. Traditional type 1 pressure vessels are bulky and reduce the efficiency of hydrogen powered vehicles. Given that the production of hydrogen currently requires a significant amount of energy, it is vital that hydrogen powered vehicles are as efficient as possible. Type 5 pressure vessels provide significant advantages in terms of efficiency due to their low weight and high capacity, however producing type 5 pressure vessels is currently high in cost and a slow process. For example type 5 pressure vessels can be made by wrapping the composite around a mandrel which is subsequently removed from the pressure vessel, for example by melting or dissolving the mandrel and removing the waste from the pressure vessel. This process is high in cost and slow, and therefore does not provide an attractive scalable manufacturing process for high quantity manufacturing.

[0039] Examples disclosed herein aim to overcome these challenges by providing composite overwrapped pressure vessels in which the composite overwrap provides both the sealing and structural requirements of the pressure vessel, thereby providing the dualfunctionality advantage of fibre composites in type 5 pressure vessels. To reduce the cost and time required to manufacture the composite overwrapped pressure vessels, the examples disclosed herein use non-sealing mandrels formed of a hollow casing which are designed to not be removed after the composite has been wrapped, and are designed to minimise the weight and loss in capacity due to keeping the mandrels within the pressure vessels.

[0040] Figure 1 illustrates an example composite overwrapped pressure vessel 100. The example composite overwrapped pressure vessel 100 comprises a tank 110, a first boss 120 and a second boss 130. The first boss 120 and the second boss 130 each provide the necessary mechanisms for enabling ingress and egress of the hydrogen into and out of the pressure vessel 100. In Figure 1 the pressure vessel comprises two bosses. All examples in the present disclosure can comprise a single boss.

[0041] The composite overwrapped pressure vessel 100 comprises a composite 140 wrapped over a mandrel (not visible in Figure 1). Examples of the composite material include fibre reinforced polymers using carbon fibres. The composite material can comprise a resin system with nanomaterial. For example the composite can comprise a filament winding structure (carbon fibre filament) impregnated with a resin for example of a thermoset plastic or epoxy having a nanomaterial filler dispersed therein, for example, by immersing it in a bath. This is then cured and hardened to form the composite, also known as a composite matrix material in which the nanomaterial filler is dispersed and the filament winding is embedded, thereby sealing, strengthening and retaining the filament winding to form a wall of the tank 110. In some examples the nanomaterial filler is a graphene nanomaterial filler. Other nanomaterial fillers are envisaged in accordance with the examples disclosed herein. Nanofiller dispersed in a filament wound carbon fibre matrix provides a lightweight, high durability, high strength wall that can be formed to shapes and mechanical properties required by design to be sufficient to robustly retain a fluid (or volatile gas) under pressure.

[0042] The necessary thickness of the composite 140 depends on the size of the pressure vessel 100, its intended storage pressure of the fluid stored within, and its specific application. In the example composite overwrapped pressure vessel 100 shown in Figure 1 and in the other examples disclosed herein, the composite 140 provides both the fluid sealing and structural strength requirements of the pressure vessel 100.

[0043] Dotted line 150 illustrates the line through which a cross-sectional view of the example composite overwrapped pressure vessel 100 is taken, the cross-section being shown in Figure 2.

[0044] Figure 2 illustrates an example composite overwrapped pressure vessel 100 in cross-section, with the composite 140 shown as the outermost layer. The composite 140 has been wrapped over a mandrel 200. The mandrel 200 comprises a hollow casing, which encloses a cavity 210 for storing fluid. The hollow casing, and therefore the mandrel 200, is non-sealing for fluid stored in the pressure vessel 100 when in use. The sealing of the fluid is provided by the composite 140 and the boss(es) of the pressure vessel 100. Figures 1 and 2 therefore show examples of an overwrapped pressure vessel 100 comprising: a mandrel 200; a composite 140 laminate wrapped over the mandrel 200; at least one boss (120, 130) arranged to enable fluid ingress and egress. The mandrel 200 comprises a hollow casing enclosing a cavity 210 for storing fluid. The hollow casing is non-sealing for fluid stored in the pressure vessel 100 when in use.

[0045] Figure 3 shows part of a composite overwrapped pressure vessel 100 according to examples disclosed herein. In particular, Figure 3 shows a cross-section of an example mandrel 200, the cross-section being taken along the longitudinal axis of the pressure vessel 100 shown in Figure 1 (with the longitudinal axis being parallel to the length of the pressure vessel 100 shown in Figure 1). Figure 3 shows the mandrel 200 comprising an example hollow casing 300 enclosing a cavity 210. The hollow casing 300 in Figure 3 comprises at least one wall 310. The at least one wall comprises a gas permeable material. For example, the gas permeable material can comprise: Linear Low Density Polyethylene (LLDPE); Medium Density Polyethylene (MDPE); High Density Polyethylene (HDPE); Low Density Polyethylene (LDPE); Cross Link Polyethylene (XLPE); EVA Copolymer (EVA); Polyvinylchloride (PVC); Nylon; Polycarbonate (PC); Polypropylene (PP).

[0046] The thickness of gas permeable material can be adapted to suit the particular requirements of the pressure vessel 100, depending on its size, the material used and the requirement to provide a surface which is rigid enough to wrap the composite 140 around. Advantageously a gas permeable material can be used, and at a relatively thin thickness, as the composite 140 provides the sealing of the fluid stored in the pressure vessel 100 (as well as the boss(es)). Weight and capacity of the pressure vessel 100 can therefore be optimised as the only requirement of the mandrel 200 is to provide a surface for overwrapping of the composite 140.

[0047] Figure 4 shows part of a composite overwrapped pressure vessel according to examples disclosed herein. In particular, Figure 4 shows a cross-section of an example mandrel 200, the cross-section being taken along the longitudinal axis of the pressure vessel 100 shown in Figure 1.

[0048] Figure 4 shows the mandrel 200 comprising an example hollow casing 400 enclosing a cavity 210. The hollow casing 400 comprises at least one wall. The at least one wall comprises perforations 410. The perforations can vary in size from sub millimetre level, millimetres and a few centimetres. The technical requirement is that the perforations 410 do not interfere with the specific overwrapping method used for the pressure vessel 100. In other words, enough of the wall needs to remain so that the layer of composite material 140 can be formed. The at least one wall in the example shown in Figure 4 can be made out of the same material as the examples referred to for the hollow casing 300 in Figure 3, or may be made out of a different material.

[0049] By providing a mandrel 200 with perforations, this advantageously reduces the weight of the pressure vessel 100 and increases the capacity of the pressure vessel compared to a similar mandrel 200 without perforations 410.

[0050] The example parts of a composite overwrapped pressure vessel 100 shown in Figures 3 and 4 can comprise a first end 320 and a second end 330. The at least one wall 310 spans between the first end 320 and the second end 330. The at least one wall 310, the first end 320 and the second end 330 can be integral. For example, the at least one wall 310, the first end 320 and the second end 330 may have been formed as one piece. Example processes for forming the one piece can be extrusion moulding, injection moulding, injection blow moulding or other appropriate processes.

[0051] In other examples, the at least one wall 310 is joined to the first end 320 and the second end 330. The joining can be done via adhesive or other appropriate joining methods.

[0052] Figure 5 shows part of a composite overwrapped pressure vessel according to examples disclosed herein. In particular, Figure 5 shows a cut-away of an example mandrel 200, the cross-section being taken along the longitudinal axis of the pressure vessel 100 shown in Figure 1. For example Figure 5 can be interpreted as a view taken by slicing the mandrel 200 in half along the longitudinal axis of the pressure vessel 100.

[0053] In the example shown in Figure 5, the mandrel 200 comprises a hollow casing 500 which comprises at least one wall 310, a first end 320 and a second end 330. The at least one wall 310 in Figure 5 comprises an extruded profile.

[0054] In Figure 5, the hollow casing 500 comprises one or more ribs 510 secured to or within the at least one wall 310. The one or more ribs 510 can provide structural rigidity to the at least one wall 310 in examples where the extruded profile is made of a flexible material, such as polyurethane or any other appropriate flexible material, including other plastic materials. In other examples the extruded profile is made of a rigid material and the one or more ribs may not be required to provide rigidity.

[0055] The one or more ribs 510 can be provided within the extruded profile or secured to the extruded profile. For example , the extruded profile can have a flat outer surface and the one or more ribs can be provided within holes running through the length of the wall(s) of the extruded profile. In examples where the one or more ribs are secured to the extruded profile, the one or more ribs can be secured to the interior surface (facing the cavity 210) of the extruded profile, with the extruded profile having a flat outer surface, which the composite is wrapped over.

[0056] The example hollow casings 300, 400 shown in Figures 3 and 4 can comprise one or more ribs 510 secured to or within the at least one wall 310. In examples where the at least one wall comprises the perforations 410, the at least one wall 310 can comprise one or more regions without perforations 410 which the one or more ribs 510 runs along.

[0057] In the example of Figure 5, the extruded profile is tubular. Other profile shapes are envisaged as being encompassed by the examples disclosed herein.

[0058] In Figures 3, 4 and 5, the first end 320 and the second end 330 are hemispherical. Other shapes of the first end 320 and the second 330 are envisaged as being encompassed by the examples disclosed herein.

[0059] In examples according to Figures 3, 4 and 5 where the at least one wall 310 is joined to the first end 320 and the second end 330, at least one of the first end 320 and the second end 330 can comprise at least one mating surface and the at least one wall 310 comprises one or more corresponding mating surfaces for joining the at least one wall to the first end and / or the second end.

[0060] For example, in examples where the at least one wall 310 is tubular and the first end 320 and the second end 330 are hemispherical, the hemispheres of the first end 320 and / or the second end 330 can comprise a stepped rim, where an outer portion of the rim is of a larger diameter than an inner portion of the rim, creating a step. The at least one wall 310, in this example being tubular, comprises regions at each end of reduced diameter which can slot into the stepped rims of each of the first end 320 and the second end 330. The stepped rim of hemispheres of the first end 320 and the second end 330 thereby contact the regions of reduced diameter of the tubular wall. This friction fit provides an example of at least one mating surface being provided by each of the first end 320 and the second end 330 and at least one mating surface being provided by the at least one wall 310. The friction fit can in some examples be further secured using adhesive or another fixing means.

[0061] In some examples, at least one of the first end 320 and the second end 330 comprises a boss interface which integrates the first end 320 or second end 330 with one of the at least one boss 120, 130. The boss interface will depend on the specific design and engineering requirements of the pressure vessel 100. For example, the boss interface may comprise an aperture in the hollow casing which allows all necessary boss components to interact with the cavity 210. The boss interface can also comprise any necessary welding and / or attachment means or mountings which secure the mandrel 200 to the boss interface.

[0062] According to some examples disclosed herein, where the at least one wall 310, and optionally the first end 320 and the second end 330 comprise a flexible material, during the overwrapping of the mandrel 200 with the composite 140, the mandrel 200 may be pressurised by inserting an output of a pump into the boss interface of the mandrel, or alternatively using the boss if that has already been installed. In examples where the mandrel 200 comprises two ends, one of the ends may be blocked during this process to prevent loss of pressure, or alternatively the end not attached to the pump may provide an exit for exhaust air. Valves or flow restriction mechanisms may be connected with the end not attached to the pump to prevent over-pressurising or under-pressuring. Pressurising in this context means supporting the mandrel 200 so that it is inflated to prevent the at least one wall from collapsing.

[0063] At least some examples, including those shown in Figures 3, 4, and 5, can provide a composite overwrapped pressure vessel 100 with a cross-section as shown in Figure 2. For example, the dashed lines 340, 420, illustrate where the cross-section is taken in these Figures, noting that in Figure 4 it misses any of the perforations 410. Examples where the least one wall 310 comprises an extruded profile without one or more ribs 510 can also have a cross-section as represented by Figure 2.

[0064] Figures 6-11 show example parts of composite overwrapped pressure vessels 100 where the hollow casing comprises a first end, a second end, a framework spanning between the first end and the second end. The composite is wrapped over the first end, the second end and the framework. The framework is “open” in that air can pass through the framework into the cavity. The framework can therefore be referred to as an open framework. The framework is a hollow casing because it encloses the cavity or empty space inside it.

[0065] The framework can also be referred to as a cage. The sides of the cage are open, allowing the inside of the cavity 210 to be observed from outside the hollow casing.

[0066] According to examples disclosed herein, including those shown in Figures 6-11, the first end and the second end can each comprise a hemisphere, with the framework spanning between the first end and the second end and secured to the rim of each hemisphere. In other examples the first end and the second end can be different shape, for example the first end and the second end can be a flat disc.

[0067] Advantageously, by using a framework the weight of the mandrel can be reduced due to the framework having less material than a solid wall. The capacity of the pressure vessel 100 can also be increased by reducing the amount of material required in the mandrel.

[0068] Figure 6 shows part of a composite overwrapped pressure vessel according to examples disclosed herein. Figure 7 shows a cross sectional view taken through the line 640.

[0069] In the example of Figures 6 and 7, the hollow casing 600 comprising the framework comprises a plurality of beams 610. Each of the plurality of beams 610 extend between the first end 620 and the second end 630. The composite 140 (not shown) is wrapped over and contacts the plurality of beams 610.

[0070] The plurality of beams 610, the first end 620 and the second end 630 can be made of a variety of materials, such as plastic, metal or wood. Advantageously, as well as providing the advantages described above, the flexibility of materials which the first end 620, second end 630 and plurality of bars 610 can be made of makes it easier, and theoretically cheaper, to produce the mandrels, which is beneficial for scalability of the manufacturing process. The flexibility in choice of materials is made possible by the fact that the mandrel is not required to produce any fluid sealing or structural strength in the composite overwrapped pressure vessel 100, as the gas sealing and structural strength is provided by the composite 140 overwrap.

[0071] In the examples disclosed herein, the plurality of beams 610 can also be referred to as stringers or bars.

[0072] Figure 8 shows part of a composite overwrapped pressure vessel according to examples disclosed herein. Figure 9 shows a cross-sectional view taken through the dashed line 850.

[0073] In the example shown in Figures 8 and 9, the framework comprises a plurality of tensioned flexible rods 810. As shown, each of the plurality of tensioned flexible rods 810 of the hollow casing 800 extend between the first end 820 and the second end 830. The composite 140 (not shown) is wrapped over and contacts the plurality of tensioned flexible rods 810.

[0074] In examples, including those shown in Figures 8 and 9, the composite overwrapped pressure vessel 100 can additionally comprise a tensioning bar 840. The tensioning bar 840 extends within the cavity and is attached to the first end and second end. The tensioning bar tensions the plurality of tensioned flexible rods 810.

[0075] The plurality of tensioned flexible rods 810 can extend in a substantially parallel direction to a direction in which the tensioning bar extends.

[0076] The plurality of tensioned flexible rods 810 can extend in a direction offset by an angle to a direction in which the tensioning bar extends.

[0077] The plurality of flexible rods 810 can be made of any suitable material, such as plastic, metal, and in some examples the same material as the composite overwrap.

[0078] The plurality of flexible rods 810 can be attached to pegs or other mounting means provided around the rims of the first end 820 and the second end 830.

[0079] Figure 10 shows part of a composite overwrapped pressure vessel according to examples disclosed herein. Figure 11 shows a cross-sectional view taken through the dashed line 1040.

[0080] In Figures 10 and 11, the hollow casing 1000 comprises a framework which comprises a lattice 1010 extending between first end 1020 and second end 1030. In some examples the lattice is a single integral structure. The lattice can comprise a plurality of separate bars which have been arranged and attached in a lattice structure.

[0081] The lattice can comprise any suitable material, such as metal, wood, plastic.

[0082] In the examples disclosed herein, the wrapping of the composite can be carried out using various different processes, including filament winding, braiding, Automated Fibre Placement (AFP).

[0083] The examples disclosed herein encompass composite overwrapped pressure vessels 100 of different sizes. The mandrel, the composite used and the thickness of the composite vary depending on the size and application of the composite overwrapped pressure vessel 100. As the mandrel is not required for fluid sealing or structural strength of the composite overwrapped pressure vessel 100, the design and structure of the mandrel is flexible and can be made comparatively light in weight and to optimize capacity of the pressure vessel compared to previous mandrels.

[0084] Depending on the application, the fluid stored in the example composite overwrapped pressure vessel can be stored at various different pressures. As the mandrel 200 is not required for fluid sealing, advantageously a variety of mandrel designs can be used for different pressure vessel applications and required pressures.

[0085] In the examples shown in the Figures and discussed herein, the pressure vessels 100 shown comprise hemispherical ends with either a wall or a framework extending between, which is either cylindrical in shape or follows the outline of a cylinder in the examples with a framework. In other example, different shapes of pressure vessels are envisaged. For example, the pressure vessel can be any of, but not limited to: spherical, cuboidal, cylindrical with flat ends. In some examples, the pressure vessel 100 can be conformal in shape in that it is formed as a specific irregular shape which is optimised for the location in a vehicle which the pressure vessel 100 is to be located.

[0086] Figure 12 shows an automotive vehicle 1200 comprising a composite overwrapped pressure vessel 100 according to the examples disclosed herein. In some examples, the automotive vehicle 1200 comprises a vessel 100 as part of its powertrain. The automotive vehicle 1200 can be any of, but is no limited to: motorbikes, cars, light goods vehicles (LGVs), heavy goods vehicles (HGVs), trains, buses, trams.

[0087] Figure 13 shows a watercraft 1300 comprising a composite overwrapped pressure vessel 100 according to the examples disclosed herein. In some examples, the watercraft 1300 comprises a composite overwrapped pressure vessel 100 as part of its propulsion or marine propulsion system. The watercraft 1300 can be any of, but not limited to: boats, yachts, ships.

[0088] Figure 14 shows an aircraft 1400 comprising a composite overwrapped pressure vessel 100 according to examples disclosed herein. In some examples, the aircraft 1400 comprises a composite overwrapped pressure vessel 100 as part of its propulsion system. The aircraft 1400 can be any of, but not limited to: propeller planes, jet airplanes, helicopters.

[0089] A spacecraft can be provided comprising a composite overwrapped pressure vessel 100 according to examples disclosed herein. In some examples, the spacecraft comprises a composite overwrapped pressure vessel 100 as part of its propulsion system. For example, the composite overwrapped pressure vessel can be used as a store of hydrogen for use as a fuel to power thrusters on a spacecraft.

[0090] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0091] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0092] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A composite overwrapped pressure vessel comprising:a mandrel;a composite laminate wrapped over the mandrel;at least one boss arranged to enable fluid ingress and egress;wherein the mandrel comprises:a hollow casing enclosing a cavity for storing fluid;wherein the casing is non-sealing for fluid stored in the pressure vessel when in use.

2. A composite overwrapped pressure vessel as claimed in claim 1, wherein the hollow casing comprises at least one wall.

3. A composite overwrapped pressure vessel as claimed in claim 2, wherein the at least one wall comprises a gas permeable material.

4. A composite overwrapped pressure vessel as claimed in 2 or 3, wherein the at least one wall comprises perforations.

5. A composite overwrapped pressure vessel as claimed in any of claims 2 to 4, wherein the hollow casing comprises a first end and a second end, wherein the at least one wall spans between the first end and the second end.

6. A composite overwrapped pressure vessel as claimed in claim 5, wherein the at least one wall, the first end and the second end are integral.

7. A composite overwrapped pressure vessel as claimed in any of claims 2 to 5, wherein the at least one wall is joined to the first end and the second end.

8. A composite overwrapped pressure vessel as claimed in claim 7, wherein at least one of the first end and the second end comprises at least one mating surface and the at least one wall comprises one or more corresponding mating surfaces for joining the atleast one wall to the first end and / or the second end.

9. A composite overwrapped pressure vessel as claimed in claim 5-8, wherein at least one of the first end and the second end comprises a boss interface which integrates the first end or second end with one of the at least one boss.

10. A composite overwrapped pressure vessel as claimed in any of claims 2 to 9, wherein the at least one wall comprises an extruded profile.

11. A composite overwrapped pressure vessel as claimed in any of claims 2 to 10, wherein the hollow casing comprises one or more ribs secured to or within the at least one wall.

12. A composite overwrapped pressure vessel as claimed in any of claims 2 to 11, wherein the at least one wall is tubular.

13. A composite overwrapped pressure vessel as claimed in any of claims 5 to 6 or claims 7-12 when dependent upon claim 5, wherein the first end and the second end are hemispherical.

14. A composite overwrapped pressure vessel as claimed in claim 1, wherein the hollow casing comprises a first end, a second end, a framework spanning between the first end and the second end, wherein the composite is wrapped over the first end, the second end and the framework.

15. A composite overwrapped pressure vessel as claimed in claim 14, wherein the framework comprises a plurality of beams, each of the plurality of beams extending between the first end and the second end, wherein the composite is wrapped over and contacts the plurality of beams.

16. A composite overwrapped pressure vessel as claimed in claim 14, wherein the framework comprises a plurality of tensioned flexible rods, each of the plurality of tensioned flexible rods extending between the first end and the second end, wherein thecomposite is wrapped over and contacts the plurality of tensioned flexible rods.

17. A composite overwrapped pressure vessel as claimed in claim 16, wherein the composite overwrapped pressure vessel additionally comprises a tensioning bar, extending within the cavity and attached to the first end and second end, wherein the tensioning bar tensions the plurality of tensioned flexible rods.

18. A composite overwrapped pressure vessel as claimed in claim 17, wherein the plurality of tensioned flexible rods extend in a substantially parallel direction to a direction in which the tensioning bar extends.

19. A composite overwrapped pressure vessel as claimed in claim 17, wherein the plurality of tensioned flexible rods extend in a direction offset by an angle to a direction in which the tensioning bar extends.

20. A composite overwrapped pressure vessel as claimed in claim 14, wherein the framework comprises a lattice.

21. A composite overwrapped pressure vessel as claimed in claim 20, wherein the lattice is a single integral structure.

22. An automotive vehicle comprising at least one composite overwrapped pressure vessel as claimed in any preceding claim.

23. A watercraft comprising at least one composite overwrapped pressure vessel as claimed in any of claims 1 to 21.

24. An aircraft comprising at least one composite overwrapped pressure vessel as claimed in any of claims 1 to 21.18

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