A method of manufacturing a composite pressure vessel and a composite pressure vessel

Abstract

A method of manufacturing a composite pressure vessel, and a composite pressure vessel 480, the method comprises mixing and dispersing plasma functionalised nanomaterial powder in a resin, impregnating fibre material 410 with the nanomaterial enhanced resin to create a composite 470; winding the composite to produce composite layers of the composite pressure vessel; winding compresses the nanomaterial enhanced resin, and a curing phase., wherein, the compression forces nanomaterial particles of the resin into microscopic voids within the composite layers. A wet wind process maybe used to impregnate fibre bundles or sheet with the resin, a sheet maybe sliced into tapes. The nanomaterial may be graphene and the resin may be an epoxy resin. The fibres may comprise carbon and may be fed through a resin bath 300 using rollers 420, 422. The composite pressure vessel may be wrapped around a mandrel rotated 490. The composite pressure vessel may be for storing a fluid, such as hydrogen, for use as a fuel in automotive vehicles, watercraft and aircraft.

Description

[0001] This invention relates to a method of manufacturing a composite pressure vessel and a composite pressure vessel, in particular the composite pressure vessel is 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 pressure vessel. BACKGROUND

[0002] Composite pressure vessels are vessels designed to hold a fluid under pressure. Typically they comprise a liner wrapped with a fibre composite, or are wrapped on a removable mandrel without a liner in the case of Type 5 liner-less composite pressure vessels referred to below. 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 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 method of manufacturing a composite pressure vessel, a composite pressure vessel, an automotive vehicle comprising a composite pressure vessel, a watercraft comprising a composite pressure vessel, an aircraft comprising a composite pressure vessel.

[0010] In accordance with the present disclosure, there is provided a method of manufacturing a composite pressure vessel, comprising: forming a nanomaterial enhanced resin, comprising: mixing plasma functionalised nanomaterial powder in a resin to create the nanomaterial enhanced resin, wherein the plasma functionalisation of the nanomaterial powder disperses the nanomaterial powder in the resin; the method further comprising: impregnating fibre material with the nanomaterial enhanced resin to create a composite; winding the composite to produce composite layers of the composite pressure vessel; wherein the winding of the composite layers compresses the nanomaterial enhanced resin, wherein whilst the nanomaterial enhanced resin is in a curing phase, the compression of the nanomaterial enhanced resin forces nanomaterial particles of the nanomaterial enhanced resin into microscopic voids within the composite layers.

[0011] In some examples, the fibre material comprises filament bundles or fibre bundles.

[0012] In some examples, the filament bundles or fibre bundles are impregnated with the nanomaterial enhanced resin using a wet wind process.

[0013] In some examples, the fibre material comprises fibre sheet.

[0014] In some examples, the fibre sheet is impregnated with the nanomaterial enhanced resin using a pre-preg process to produce a composite sheet.

[0015] In some examples, the method comprises slicing the composite sheet into composite tape prior to the winding of the composite.

[0016] In some examples, the method comprises slicing the fibre sheet into fibre tape, and wherein the fibre tape is impregnated with the nanomaterial enhanced resin using a tow-preg process.

[0017] In some examples, the nanomaterial comprises graphene.

[0018] In some examples, the resin comprises epoxy resin.

[0019] In some examples, the epoxy resin is unmodified before mixing with the plasma functionalised nanomaterial powder.

[0020] In some examples, the fibre material comprises carbon.

[0021] In some examples, the composite pressure vessel satisfies Regulation No. 134 of the Economic Commission for Europe of the United Nations.

[0022] In some examples, the composite is wound around a liner to create a Type 4 composite pressure vessel.

[0023] In some examples, the composite is wound without a liner to create a Type 5 composite pressure vessel.

[0024] In accordance with the present disclosure, there is provided a composite pressure vessel made according to the method of any preceding paragraph.

[0025] In accordance with the present disclosure, there is provided a composite pressure vessel, wherein the composite comprises a fibre material impregnated with nanomaterial enhanced resin, the nanomaterial enhanced resin comprising plasma functionalised nanomaterial dispersed within a resin.

[0026] In some examples, the resin comprises an epoxy resin.

[0027] In some examples, the epoxy resin is unmodified.

[0028] In some examples, the nanomaterial comprises graphene.

[0029] In some examples, the fibre material comprises carbon.

[0030] In accordance with the present disclosure, there is provided an automotive vehicle comprising a composite pressure vessel of any preceding paragraph.

[0031] In accordance with the present disclosure, there is provided a watercraft comprising a composite pressure vessel of any preceding paragraph.

[0032] In accordance with the present disclosure, there is provided an aircraft comprising a composite pressure vessel of any of any preceding paragraph.

[0033] In accordance with the present disclosure, there is provided a method of manufacturing a composite pressure vessel, comprising: forming a nanomaterial enhanced resin, comprising: mixing plasma functionalised nanomaterial powder in a resin to create the nanomaterial enhanced resin, wherein the plasma functionalisation of the nanomaterial powder disperses the nanomaterial powder in the resin; the method further comprising: impregnating fibre material with the nanomaterial enhanced resin to create a composite; winding the composite to produce composite layers of the composite pressure vessel. 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 method of manufacturing a composite pressure vessel according to examples disclosed herein; Figure 2 shows part of a method of manufacturing a composite pressure vessel according to examples disclosed herein; Figure 3 shows a resin bath containing a nanomaterial enhanced resin according to examples disclosed herein; Figure 4 shows an example system for manufacturing a composite pressure vessel according to examples disclosed herein; Figure 5 shows part of an example system for manufacturing a composite pressure vessel according to examples disclosed herein; Figure 6 shows part of an example system for manufacturing a composite pressure vessel according to examples disclosed herein; Figure 7 shows part of an example system for manufacturing a composite pressure vessel according to examples disclosed herein; Figure 8A shows a schematic example of a composite pressure vessel according to examples disclosed herein; Figure 8B shows a schematic cross section of an example composite pressure vessel according to examples disclosed herein; Figure 8C shows a schematic cross section of an example composite pressure vessel according to examples disclosed herein; Figure 9 shows an example automotive vehicle comprising a composite pressure vessel according to examples disclosed herein; Figure 10 shows an example watercraft comprising a composite pressure vessel according to examples disclosed herein; Figure 11 shows an example aircraft comprising a composite 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 cell 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, as well as the necessary sealing and containment of the hydrogen. 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 4 and Type 5 pressure vessels provide significant advantages in terms of efficiency due to their low weight and high capacity, however producing Type 4 and Type 5 pressure vessels is currently high in cost, complex and a slow process.

[0039] One issue with producing Type 4 and Type 5 composite pressure vessels is the porosity of the composite material. Porosity undermines the structural integrity, sealing and containment of hydrogen. The consequences of porosity are multifaceted and significant, particularly for hydrogen storage.

[0040] Porosity refers to the presence of very small voids or gaps within the composite material. These imperfections, often microscopic, can originate due to factors including improper resin curing, resin coverage or inadequate compaction of the composite layers.

[0041] The structural integrity of the composite pressure vessel is affected because the porosity can lead to uneven stress distribution, making the vessel more susceptible to damage under pressure or during impact, which is crucial in applications such as automotive vehicles, where safety and reliability are paramount.

[0042] The sealing and containment of hydrogen is affected by porosity because of the exceptionally small size of the hydrogen molecules, which allows the hydrogen to permeate through the very small voids or gaps, leading to a gradual loss of stored hydrogen, reducing the efficiency of the composite pressure vessel.

[0043] Additionally, permeability and structural integrity of composite pressure vessels are critical for satisfying standards required by transport authorities. The ability to use Type 4 and Type 5 composite pressure vessels in vehicles is therefore dependent upon porosity being low.

[0044] Addressing porosity in composite pressure vessels is therefore a significant challenge. It requires efficient precision in manufacturing and often, advanced nondestructive evaluation methods to detect and quantify these voids, ensuring the safety and the efficiency of hydrogen storage. To improve scalability, reduce cost and time to manufacture composite pressure vessels, a method is required which provides a composite wrap with low porosity in a reliable and consistent manner.

[0045] Examples disclosed herein address these challenges by providing a nanomaterial enhanced resin which provides gap filling ability when compared to a standard resin. This gap filling is a key tool in reducing the porosity of composite structures. The gap filling is provided by torturous paths for the hydrogen molecules when permeating through the composite, as discussed further below. The nanomaterial enhanced resin can penetrate and fill the microscopic voids within the composite layers. During winding of the composite to produce composite layers of the composite pressure vessel, the nanomaterial enhanced resin is compressed which, whilst the nanomaterial enhanced resin is in a curing phase, forces the nanomaterial particles of the nanomaterial enhanced resin into the microscopic voids within the composite layers. Filling the microscopic voids within the composite layer significantly reduces the porosity of the material. The reduction in voids decreases the permeability of the vessel to hydrogen, thereby minimising the risk of hydrogen leakage and improving the overall efficiency of hydrogen storage within the composite pressure vessel.

[0046] The presence of voids within the composite materials can also create weak points, making the vessel more susceptible to damage under pressure or impact. A gap filling resin can strengthen these weak points by providing a more uniform and continuous matrix, which helps in distributing stress more evenly across the composite pressure vessel. This uniformity enhances the composite pressure vessel’s structural integrity and reliability, particularly under high pressure conditions.

[0047] The nanomaterial enhanced resin according to examples disclosed herein with gap filling properties can also aid in compensating for minor inconsistencies in composite layer application, ensuring a more uniform and defect free end product. This improvement in manufacturing quality provides composite pressure vessels which are more reliable and safer for long-term use, as well as reducing the likelihood of a manufactured composite pressure vessel failing the necessary tests required by standards.

[0048] The nanomaterial enhanced resin according to examples disclosed herein can lead to a reduction in porosity by at least 30% compared to using standard resin.

[0049] The nanomaterial enhanced resin according to examples disclosed herein is capable of producing composite pressure vessels which pass necessary standards tests. For example, Regulation No. 134 of the Economic Commission for Europe of the United Nations provides details and testing requirements for the safe operation of hydrogen powered vehicles. Part 1 of Regulation No. 134 specifies performances tests which hydrogen storage systems need to meet. These tests include: • 1) Verification tests for baseline metrics (baseline initial burst pressure, baseline initial pressure cycle life) • 2) Verification test for performance durability [hydraulic sequential tests] (proof pressure test, drop (impact) test, surface damage, chemical exposure and ambient temperature pressure cycling tests), high temperature static pressure test, Extreme temperature pressure cycling, residual proof pressure test, residual strength burst test) • 3) Verification test for expected on-road system performance [pneumatic sequential tests] (proof pressure test, ambient and extreme temperature gas pressure cycling test (pneumatic), extreme temperature static gas pressure leak / permeation test (pneumatic), residual proof pressure test, residual strength burst test (hydraulic) • 4) Verification test for service terminating system performance in Fire • 5) Verification test for performance durability of primary closures The porosity of the composite material will directly impact at least the tests covered by 1) to 4).

[0050] Other standards can also be met using the methods disclosed herein using nanomaterial enhanced resin. The necessary tests can vary depending on the intended storage pressure of the pressure vessels.

[0051] For example, for 25 MPa (3.6 ksi) storage pressure, the standards to be complied with can be: NGV2-2000 (modified), DOT FMVSS 304 (modified).

[0052] For example, for 35 MPa (5 ksi) storage pressure, the standards to be complied with can be: E.I.H.P. / Rev 12B, ISO 15869 (derived from EU 97 / 23 / EG), NGV2-2000 (modified), FMVSS 304 (modified), Reijikijyun Betten 9.

[0053] For example, for 70 MPa (10 ksi) storage pressure, the standards to be complied with can be: E.I.H.P. / Rev 12B, ISO 15869 (derived from EU 97 / 23 / EG), FMVSS 304 (modified), Betten 9 (modified).

[0054] The nanomaterial enhanced resin system with gap filling properties in the manufacture of composite pressure vessels therefore addresses the critical issue of porosity. It enhances the safety, efficiency and longevity of these vessels, making them more suitable for the requirements of hydrogen storage within composite pressure vessels.

[0055] Figure 1 shows a method 100 of manufacturing a composite pressure vessel according to examples disclosed herein. The method 100 comprises, in a first block, forming 110 a nanomaterial enhanced resin.

[0056] Figure 2 shows part of a method 100 of manufacturing a composite pressure vessel according to examples disclosed herein. In particular Figure 2 shows the forming 110 of the nanomaterial enhanced resin comprises: mixing 115 plasma functionalised nanomaterial powder in a resin to create the nanomaterial enhanced resin. The plasma functionalisation of the nanomaterial powder disperses the nanomaterial powder in the resin.

[0057] Turning back to Figure 1, the method 100 further comprises in a second block: impregnating 120 fibre material with the nanomaterial enhanced resin to create a composite. The method 100 comprises in a third block: winding 130 the composite to produce composite layers of the composite pressure vessel. The winding of the composite layers compresses the nanomaterial enhanced resin. Whilst the nanomaterial enhanced resin is in a curing phase, the compression of the nanomaterial enhanced resin forces nanomaterial particles of the nanomaterial enhanced resin into microscopic voids within the composite layers.

[0058] The presence of the plasma functionalised nanomaterial within the nanomaterial enhanced resin reduces the porosity of these voids within the composite material due to the size of the nanomaterial (approximately 10'9 centimetres as an example), which allows to them to create tortuous paths between the molecules of the composite material. This means that hydrogen molecules do not have a “straight line” path or easy path to permeate through the composite material, between adjacent composite material molecules. The tortuous path in effect provides a maze through which the hydrogen molecules have to travel to permeate through the composite layers which impedes their progress. This therefore creates a barrier to hydrogen and reduces the permeation of the composite layers of the composite pressure vessel.

[0059] Plasma functionalisation of nanomaterials is a known process in which a sample of nanomaterials are treated in a plasma field which has a chemical added, which under specific processing conditions attaches to the particles of the nanomaterial and enables property modification. Typical chemical bonded functional groups include oxygen, nitrogen, fluorine. Once functionalised, the nanomaterial has been found to have increased dispersal properties, and are in general less inert. This makes it ideal to introduce into a resin to enable a consistent concentration of the nanomaterial throughout the resin. The plasma functionalisation also improves the affinity of the nanomaterial enhanced resin to the fibre material. This advantageously means that the plasma functionalised nanomaterial introduced into the resin will cause anywhere that the resin is present to have the beneficial properties of gap filling. An example process of plasma functionalisation can be found on https: / / haydale.com / functjonaHsed--Qraphene / (Haydale). The parameters of the plasma functionalisation process can be tailored depending on the specific application of the nanomaterial enhanced resin, which will depend on the type of winding system used, the materials used for the resin, the nanomaterial itself, the fibre material and the design of the composite pressure vessel including its intended use, required specifications, size and capacity, etc..

[0060] Once the nanomaterial has been functionalised, it can be made into a masterbatch which then can then be introduced into the resin.

[0061] Figure 3 shows a resin bath 300 containing a nanomaterial enhanced resin 310 according to examples disclosed herein.

[0062] According to examples, the fibre material comprises filament bundles or fibre bundles. It is to be understood that the methods, systems and composite pressure vessels described herein are not limited to one of filament bundles or fibre bundles, they are alternatives. For example the systems described herein in some examples can use filament bundles and fibre bundles interchangeably. The filament bundles can comprise, as examples, bundles of 3000, 6000 or 12000 individual filaments. Filaments or fibres can also be referred to as roving. Filament bundles can be referred to as continuous filament bundles. The filament bundles or fibre bundles can then be fed through a resin bath 300 containing the nanomaterial enhanced resin 310. As shown in Figure 3 the nanomaterial enhanced resin 310 contains the plasma functionalised nanomaterial spread substantially uniformly around the resin 310, as illustrated schematically by the dots in the resin 310. Depending on the specific design of the composite pressure vessel, the nanomaterial used and the resin used, the temperature and / or the mix of the resin can be adjusted to create a thinner or thicker I lower or higher viscosity resin.

[0063] According to examples, the filament bundles or fibre bundles are impregnated with the nanomaterial enhanced resin using a wet wind process.

[0064] Figure 4 shows an example system 400 for manufacturing a composite pressure vessel 480 according to examples disclosed herein. The system 400 shown in Figure 4 is an example of enacting the method 100.

[0065] As shown in Figure 4, the filament bundles or fibre bundles 410 are fed through the resin bath 300 using resin bath rollers 420, 422. The filament bundles or fibre bundles 410 may have been separated using combs not shown in Figure 4. The filament bundles or fibre bundles 410 can originate from spools / rolls, again not shown. Whilst in the resin bath 300, the filament bundles or fibre bundles 410 are impregnated with the nanomaterial enhanced resin, which then leads to the composite 430 emerging from the resin bath 300. The composite 430 in this example can be referred to as wetted filament bundles or wetted fibre bundles or wetted tows. In Figure 4 the composite 430 then passes through to guide apparatus 460. Guide apparatus 460 winds the composite to produce the composite layers 482 of the composite pressure vessel 480. Typically the composite pressure vessel 480 is wrapped around a mandrel which is rotated as illustrated by arrow 490. The guide apparatus 460 can comprise any one or more of: nip rollers, combs, wet-out bars and other guidance devices. Combs, for example, are used to space filaments 410 for winding. Nip rollers control excess resin, and also guide and shape the filaments onto the mandrel which the composite pressure vessel is wound around.

[0066] Figure 5 shows part of an example system 400 for manufacturing a composite pressure vessel 480 according to examples disclosed herein.

[0067] As shown in Figure 5, the guide apparatus 460 is capable of translation, typically in the directions shown by arrows 500, 502 to translate in opposite directions parallel to the longitudinal axis of the composite pressure vessel 480. The translational movement of the guide apparatus 460 back and forth, in combination with the rotational movement of the composite pressure vessel 480, as shown by arrow 510 in Figure 5, causes the necessary winding pattern to create the composite pressure vessel 480 according to the specific design chosen by winding the winding composite 470 emerging from the guide apparatus 460. The winding composite 470 can for example comprise filament bundles separated by combs, or fibre bundles. The guide apparatus 460 can comprise motors and other devices for enabling the translational movement.

[0068] The guide apparatus 460 can comprise any of the necessary components for delivering the winding pattern as required. For example the guide apparatus 460 can comprise at least one processor, at least one memory, where the at least one memory stores computer program instructions necessary for performing the winding pattern required for a design. The guide apparatus 460 can receive sensor signals indicating the position of the guide apparatus 460 and the rotational movement of the composite pressure vessel 480, the distance from the composite pressure vessel, etc.. The guide apparatus can comprise sensors which provide the sensor signals indicating the position of the guide apparatus.

[0069] According to examples disclosed herein, one or more parts / devices of the guide apparatus 460 can be distributed. For example, combs, or other parts / devices, may not perform the translational movement as illustrated in Figure 5.

[0070] In the examples shown in Figures 4 and 5 and described herein, the nanomaterial enhanced resin in the wet-wind process can be cured by controlling the temperature and pressure applied to the wound composite pressure vessel, as well as the timing for exposing the nanomaterial enhanced resin to various temperatures / pressures.

[0071] As will be appreciated, any of the processes / steps described herein with reference to Figures 4 and 5 can form part of the method 100. For example, the method 100 shown in Figures 1 and 2 and described herein can comprise: obtaining filament bundles or fibre bundles 410; inserting the filament bundles or fibre bundles into resin bath 300 to impregnate them with the nanomaterial enhanced resin; passing composite 430 into guide apparatus 460, and using the guide apparatus to wind winding composite 470 around a mandrel to produce the composite pressure vessel 480.

[0072] Figure 6 shows part of an example system 600 for manufacturing a composite pressure vessel according to examples disclosed herein. The system 600 shown in Figure 6 is an example of enacting the method 100.

[0073] According to examples, the fibre material can comprise fibre sheet. Figure 6 illustrates an example where the fibre material comprises fibre sheet. In this example, the fibre sheet 630 is provided from a roll 610. The roll 610 may vary in length, as well as the fibre sheet wound round the roll 610. Typically the length can be on the order of 1 metre or more.

[0074] In the example of Figure 6, the nanomaterial enhanced resin is also provided as a sheet 640 from a roll 620. For example, the nanomaterial enhanced resin can be provided as a hotmelt, which is later activated when making the composite pressure vessel 480. The mixing of the plasma functionalised material powder in a resin can therefore include mixing the plasma functionalised material powder with the resin sheet to create the nanomaterial enhanced resin. Again, the enhanced dispersal abilities of the plasma functionalised nanomaterial enables a uniform distribution of the plasma functionalised nanomaterial throughout the resin sheet.

[0075] Figure 6 shows the fibre sheet 630 and the resin sheet 640 being bonded together using bonding rollers 650, 652, providing the composite material as a composite material sheet 660. The composite material sheet 660 is sliced into composite material tape 680 using a cutting device 670, which can comprise roller cutters or any other appropriate apparatus for cutting composite sheet 660 into composite tape 680. The composite tape 680 is in the order of one or a few centimetres wide. The composite tape 680 is then wound onto tape rolls 690 shown in Figure 6. These composite tape rolls 690 can then be transported elsewhere to a different part of the factory or a different factory to continue the method 100 as shown in Figure 7. In other examples, instead of transferring the composite material sheet 660 into the cutting device 670, the composite material sheet 660 is wound onto a roll and transferred elsewhere for cutting into composite tape 680 and winding the tape 680 onto tape rolls 690 at a later time.

[0076] Therefore as shown Figure 6, according to examples, the fibre sheet are impregnated with the nanomaterial enhanced resin using a pre-preg process.

[0077] As shown in Figure 6, according to examples, the method 100 comprises slicing the composite sheet into composite tape prior to the winding of the composite.

[0078] Figure 7 shows part of an example system 600 for manufacturing a composite pressure vessel 480 according to examples disclosed herein.

[0079] According to the example shown in Figure 7, the tape rolls 690 can be unwound to provide unwound composite tape 710 which can then be fed into a guide apparatus 720 which then provides composite wind tape 730 for winding around composite pressure vessel 480 to produce the composite layers 482 as the composite pressure vessel 480 is rotated, for example by mandrel, as illustrated by arrow 490. Guide apparatus 720 in this example comprises any required apparatus for managing the various strands of composite tape 710 being fed to it. For example it may selectively unwind one tape roll 690 at a time until it is used up and then comprise necessary mechanisms to transfer to using another tape roll 690.

[0080] As with the guide apparatus 460 shown in Figure 4, the guide apparatus 720 can comprise any of the necessary components for delivering the winding pattern as required. For example the guide apparatus 720 can comprise at least one processor, at least one memory, where the memory stores computer program instructions necessary for performing the winding pattern required for a design. The guide apparatus 720 can receive sensor signals indicating the position of the guide apparatus 720 and the rotational movement of the composite pressure vessel 480, the distance from the composite pressure vessel 480, etc..

[0081] In the example of Figure 7, after or whilst the composite material has been wound, the composite pressure vessel 480 can have heat applied to it in order to cure the resin. Whilst the resin is heated and in a curing phase, it is able to flow, and this in combination with the compression from the winding of the composite layers forces the nanomaterial particles of the nanomaterial enhanced resin into the microscopic voids within the composite layers. In some examples, an autoclave process or shrink wrap may be used during the curing process, which can also apply pressure to force the nanomaterial enhanced resin into the microscopic voids.

[0082] As an alternative to the system 600 shown in Figures 6 and 7 described herein, a system can be provided which is an example of enacting method 100 described herein, wherein the fibre sheet 630 is first sliced into fibre tape, and then passed through an impregnation apparatus which applies the nanomaterial enhanced resin to the fibre tape to provide composite tape. The composite tape can then be wound onto tape rolls 690 for later use. The tape rolls 690 can then be wound around a mandrel using a guide apparatus 720, and the composite pressure vessel 480 can have heat applied to cure the resin as described herein. This is an example of a tow-preg process. The method 100 can therefore comprise: slicing the fibre sheet into fibre tape, and wherein the fibre tape is impregnated with the nanomaterial enhanced resin using a tow-preg process.

[0083] As will be appreciated, any of the processes / steps described herein with reference to Figures 6 and 7 in relation to a pre-preg process or a tow-preg process can form part of the method 100. For example, the method 100 shown in Figures 1 and 2 and described herein can comprise, for a pre-preg process: obtaining fibre sheet 630; obtaining resin sheet 640; pressing the fibre sheet 630 and resin sheet 640 together to form composite sheet 630; cutting composite sheet 630 to produce composite tape 680; winding composite tape 680 to produce the composite pressure vessel 480; heating the composite pressure vessel 480 to put the nanomaterial enhanced resin into a curing phase for curing. For example, the method 100 shown in Figures 1 and 2 and described herein can comprise, for a tow-preg process: obtaining fibre sheet 630; cutting fibre sheet 630 to produce fibre tape 680; impregnating fibre tape 680 with nanomaterial enhanced resin to produce composite tape 680; winding composite tape 680 to produce the composite pressure vessel 480; heating the composite pressure vessel 480 to put the nanomaterial enhanced resin into a curing phase for curing.

[0084] Figure 4 shows an example of a wet wind process and Figures 6 and 7 show and describe examples of a pre-preg process and a tow-preg process. Any of these processes can be provided as a roll to roll process. For example the wet wind process can start from rolls of filament bundles or fibre bundles and ends with the roll of composite layers 482 provided on the composite pressure vessel 480. The pre-preg process can start with the roll 610 of fibre sheet 630 and the roll 620 of nanomaterial enhanced resin sheet 640 and then end with the roll of composite layers 482 provided on the composite pressure vessel 480 (this assumes that either the rolls 690 are not used or instead provide a means of transferring the tape to the guide apparatus 720). Similarly, the tow-preg process can start with the roll 610 of fibre sheet 630 and end with the roll of composite layers 482 provided on the composite pressure vessel 480.

[0085] According to methods 100 disclosed herein the nanomaterial comprises graphene. Other nanomaterials are envisaged.

[0086] According to the methods 100 disclosed herein, the resin comprises epoxy resin. Other resins are envisaged. Advantageously the epoxy resin can be unmodified before mixing with the plasma functionalised nanomaterial powder. This simplifies the choice of base resin material.

[0087] According to methods disclosed herein, the fibre material comprises carbon. Other fibre materials are envisaged.

[0088] Figure 8 shows a schematic example of a composite pressure vessel 480 according to examples disclosed herein. The composite pressure vessel 480 is made according to any of the methods disclosed herein. The composite pressure vessel 480 comprises the composite layers 482, with bosses 801, 802, which are used for ingress and egress of the hydrogen into / out of the pressure vessel. In other examples the pressure vessel has one boss.

[0089] As shown in Figure 8B, the composite can be wound around a liner 810 to create a Type 4 composite pressure vessel. In other examples a Type 5 composite pressure vessel is made which does not comprise a liner as shown in Figure 8C. Figures 8B and 8C also show the cavity 820 of the composite pressure vessel 480, for storing hydrogen.

[0090] Therefore according to methods disclosed herein, the composite can be wound around a liner 810 to create a Type 4 composite pressure vessel. According to example methods disclosed herein the composite can be wound without a liner to create a Type 5 composite pressure vessel.

[0091] The composite pressure vessel 480 shown in Figures 8A-8C, comprise a composite which comprises a fibre material impregnated with nanomaterial enhanced resin as described herein. The nanomaterial enhanced resin comprises plasma functionalised nanomaterial dispersed within the resin.

[0092] According to examples, the resin comprises a epoxy resin. The epoxy resin can be unmodified. As explained above, the epoxy resin can be unmodified before mixing with the plasma functionalised nanomaterial powder. This simplifies the choice of base resin material.

[0093] According to examples, the nanomaterial comprises graphene. Other nanomaterials are envisaged.

[0094] According to examples, the fibre material comprises carbon. Other fibre materials are envisaged.

[0095] Figure 9 shows an example automotive vehicle comprising a composite pressure vessel according to examples disclosed herein. In some examples, the automotive vehicle 900 comprises a composite pressure vessel 480 as part of its powertrain. The automotive vehicle 900 can be any of, but is no limited to: motorbikes, cars, light goods vehicles (LGVs), heavy goods vehicles (HGVs), trains, buses, trams.

[0096] Figure 10 shows an example watercraft 1000 comprising a composite pressure vessel according to examples disclosed herein. In some examples, the watercraft 1000 comprises a composite pressure vessel 480 as part of its propulsion or marine propulsion system. The watercraft 1000 can be any of, but not limited to: boats, yachts, ships.

[0097] Figure 11 shows an example aircraft 1100 comprising a composite pressure vessel 480 according to examples disclosed herein. In some examples, the aircraft 1100 comprises a composite pressure vessel 480 as part of its propulsion system. The aircraft 1100 can be any of, but not limited to: propellor planes, jet airplanes, helicopters.

[0098] 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 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.

[0099] Features, integers, or characteristics 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 5 claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[00100] 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. 10

Claims

1. A method of manufacturing a composite pressure vessel, comprising:forming a nanomaterial enhanced resin, comprising:mixing plasma functionalised nanomaterial powder in a resin to create the nanomaterial enhanced resin, wherein the plasma functionalisation of the nanomaterial powder disperses the nanomaterial powder in the resin;the method further comprising:impregnating fibre material with the nanomaterial enhanced resin to create a composite;winding the composite to produce composite layers of the composite pressure vessel;wherein the winding of the composite layers compresses the nanomaterial enhanced resin;wherein whilst the nanomaterial enhanced resin is in a curing phase, the compression of the nanomaterial enhanced resin forces nanomaterial particles of the nanomaterial enhanced resin into microscopic voids within the composite layers.

2. A method as claimed in claim 1, wherein the fibre material comprises filament bundles or fibre bundles.

3. A method as claimed in claim 2, wherein the filament bundles or fibre bundles are impregnated with the nanomaterial enhanced resin using a wet wind process.

4. A method as claimed in claim 1, wherein the fibre material comprises fibre sheet.

5. A method as claimed in claim 4, wherein the fibre sheet is impregnated with thenanomaterial enhanced resin using a pre-preg process to produce a composite sheet.

6. A method as claimed in claim 5, wherein the method comprises slicing the composite sheet into composite tape prior to the winding of the composite.

7. A method as claimed in claim 4, wherein the method comprises slicing the fibre sheet into fibre tape, and wherein the fibre tape is impregnated with the nanomaterialenhanced resin using a tow-preg process.

8. A method as claimed in any preceding claim, wherein the nanomaterial comprises graphene.

9. A method as claimed in any preceding claim, wherein the resin comprises epoxy resin.

10. A method as claimed in claim 9, wherein the epoxy resin is unmodified before mixing with the plasma functionalised nanomaterial powder.

11. A method as claimed in any preceding claim, wherein the fibre material comprises carbon.

12. A method as claimed in any preceding claim, wherein the composite pressure vessel satisfies Regulation No. 134 of the Economic Commission for Europe of the United Nations.

13. A method as claimed in any preceding claim, wherein the composite is wound around a liner to create a Type 4 composite pressure vessel.

14. A method as claimed in any preceding claim, wherein the composite is wound without a liner to create a Type 5 composite pressure vessel.

15. A composite pressure vessel made according to the method of any preceding claim.

16. A composite pressure vessel, wherein the composite comprises a fibre material impregnated with nanomaterial enhanced resin, the nanomaterial enhanced resin comprising plasma functionalised nanomaterial dispersed within a resin.

17. A composite pressure vessel as claimed in claim 16, wherein the resin comprises a epoxy resin.

18. A composite pressure vessel as claimed in claim 17, wherein the epoxy resin is unmodified.

19. A composite pressure vessel as claimed in any of claims 16-18, wherein the5 nanomaterial comprises graphene.

20. A composite pressure vessel as claimed in any of claims 16-19, wherein the fibre material comprises carbon.10 21. An automotive vehicle comprising a composite pressure vessel of any of claims 15to 20.

22. A Watercraft comprising a composite pressure vessel of any of claims 15 to 20.15 23. An Aircraft comprising a composite pressure vessel of any of claims 15 to 20.

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