Patent Description:
Pressure vessels may serve as storage media (e.g., gas) for a wide variety of consumer, commercial, and industrial processes. In order to store sufficient gas for any operation within a given volume, the gas is stored at high pressure. Traditionally, pressure vessels have a typical spherical or cylindrical design that evenly distributes stress in the containment perimeter. Unfortunately, such tanks do not use allocated space efficiently. For example, a spherical vessel fills a cubic space with about fifty-two percent efficiency, and a cylindrical vessel fills a rectangular volume with approximately seventy-eight percent efficiency. More recent improvements in pressure vessels that generally conform to a rectangular volume may fill the space with about ninety percent efficiency relative to a true rectangular volume. <CIT> shows an electrical heating unit in a container facilitating release of adsorbed natural gas. The heating unit is formed of a heating rod, heating wire, or heating tape. <CIT> shows a storage tank having a plurality of briquette units inside the storage tank. Each briquette unit includes a liner of heat-conducting material. The liner includes a heat conductor, such as metal or heat conducting plastic. Heating of the briquette is achieved by letting a heat pipe or channel traverse through the briquette. <CIT> shows a vessel having an inner shell and an outer shell, wherein the outer shell is formed from a carbon fiber, a glass fiber, a composite fiber, and a fiber having a resin coating. The inner shell comprises a plurality of channels which are in fluid communication with fluid conduits, the channels forming a temperature regulating device. The channels are provided with a flow of a fluid via a temperature control system. <CIT> shows a warming system for a carbon fiber composite high pressure gas storage tank. The system comprises a resin fiber composite the tank having a shell formed from an electromagnetically active fiber material embedded in a polymeric binder; the warming system comprises a coil of conductive wire wound around the diameter of the tank interconnected with a high-frequency alternating current passed through the coil from an on board power source to produce an electromagnetic field that warms the tank by electromagnetic induction. <CIT> shows a pressure vessel for holding a pressurized fluid such as compressed natural gas including two end cells and zero or more interior cells. The cell geometry ensures that the cells meet one another at tangential circular surfaces, thereby reducing the tendency of adjacent cells to peel apart. A web secured about the cells includes two sheets that are tangent to the cells.

An absorbent may be placed inside the pressure vessel to further improve storage efficiency of the pressurized gas. To assist in extracting the gas from the vessel, the absorbent may be heated by various means.

The designs of non-spherical/cylindrical pressure vessels to support high internal pressure are complex, including variable-curvature external surfaces and internal structure to transfer stresses. The large size of a high conformable vessels and the complicated shapes makes manufacturing challenging. Moreover, the addition of absorbents with a heating means contributes toward design and manufacturing complexity and cost.

A pressure vessel assembly according to one embodiment of the present disclosure includes the features of claim <NUM>.

Preferred embodiments can be found in the dependent claims.

It should be understood that the following description and drawings are intended to be exemplary in nature and non-limiting.

Referring now to <FIG>, an example of a pressure vessel or tank assembly <NUM> configured to store a high pressure fluid is illustrated. Exemplary fluids that may be stored within the pressure vessel <NUM> include, but are not limited to, compressed natural gas (CNG), hydrogen, propane, methane, air, and hydraulic fluid, for example. The pressure vessel assembly <NUM> may generally include two flanking vessels <NUM>, <NUM> and at least one interior vessel <NUM> (e.g., five identical interior vessels illustrated) joined to and disposed between the flanking vessels <NUM>, <NUM>, Each vessel <NUM>, <NUM>, <NUM> may generally be elongated with the overall configuration of the pressure vessel assembly <NUM> generally being a rectangular shape, but as will be appreciated from the description, herein, other shapes are contemplated.

Referring to <FIG>, each vessel <NUM>, <NUM>, <NUM> may include respective liners <NUM>, <NUM>, <NUM>. Each liner <NUM>, <NUM>, <NUM> may define the boundaries of respective chambers <NUM>, <NUM>, <NUM> for the fluid storage. The flanking end liners <NUM>, <NUM> may include respective lobes <NUM>, <NUM> with lobe <NUM> closed-off by opposite end caps <NUM>, <NUM> and lobe <NUM> closed-off by opposite end caps <NUM>, <NUM>, Each lobe <NUM>, <NUM> may be circumferentially continuous and substantially cylindrical. The interior liner <NUM> may include a lobe <NUM> with the lobe <NUM> closed-off by opposite end caps <NUM>, <NUM>. Lobe <NUM> may be circumferentially continuous. The liners <NUM>, <NUM>, <NUM> may be made of any material and thicknesses capable of providing the necessary structural support, weight, operating characteristics, cost limitations and other parameters necessary for a particular application. Examples of liner material may include steel or other metallic compositions and plastic. The liners <NUM>, <NUM>, <NUM> may further be blow molded plastic, or injection molded plastic.

Referring to <FIG>, the lobes <NUM>, <NUM> of the respective flanking liners <NUM>, <NUM> may be substantially identical and are arranged such that the lobe <NUM> of the first flanking liner <NUM> is rotated about one-hundred and eighty (<NUM>) degrees relative to the lobe <NUM> of the opposite flanking liner <NUM> (i.e., are arranged as a mirror image of one-another). Each flanking lobe <NUM>, <NUM> may include a generally cylindrical outer portion or wall <NUM> and an interior portion or wall <NUM>. The interior wall <NUM> may be substantially planar and may laterally span between a first end <NUM> and a second end <NUM> of the cylindrical outer wall <NUM>. In one embodiment, the interior wall <NUM> is integrally formed with the ends <NUM>, <NUM> of the cylindrical outer wall <NUM>. At least a portion of the curvature of the cylindrical outer will <NUM> is defined by a radius R. in one embodiment, the portion of the outer wall <NUM>, opposite the interior wall <NUM>, includes a circular shape or curve generally of a two-hundred and forty (<NUM>) degree angle as defined by the radius R. Consequently, the overall height of the flanking lobes <NUM>, <NUM> is equal to double the length of the radius R of the cylindrical outer wall <NUM>. The vertical interior wall <NUM> is generally parallel to and spaced apart from a vertical plane P that includes the origin of the radius R that defines the curvature of the outer wall <NUM>. In one embodiment, the distance between the interior wall <NUM> and the parallel vertical plane ρ is about half the length of the radius R. As a result, the flanking lobes <NUM>, <NUM> generally have a width equal to about one and a half the length of the radius of curvature R of the outer wall <NUM>.

The illustrated interior lobe <NUM> includes first and second interior sidewalls <NUM>, <NUM> that may be diametrically opposite one another, substantially vertically arranged, and separated from one another by a distance. In one embodiment, the width of the interior lobe <NUM> is generally equal to the radius of curvature R of the end lobes <NUM>, <NUM>, The thicknesses of the first interior sidewall <NUM> and the second interior sidewall <NUM> may be identical and may be equal to the thickness of the interior wall <NUM> of the flanking lobes <NUM>, <NUM>. A first outside wall <NUM> extends between a first end <NUM> of the first interior sidewall <NUM> and a first end <NUM> of the second interior sidewall <NUM>. Similarly, a second outside wall <NUM> extends between a second end <NUM> of the first interior sidewall <NUM> and a second end <NUM> of the second interior sidewall <NUM>.

The curvature of the first outside wall <NUM> and the second outside wall <NUM> may be defined by a circular shape or curve generally of a sixty (<NUM>) degree angle by a radius R. In one embodiment, the radius of curvature R of the interior lobe <NUM> is substantially identical to the radius of curvature R of the flanking lobes <NUM>, <NUM>. Consequently, the distance between the first curved wall <NUM> and the second curved wall <NUM> is double the length of the radius of curvature R, and is therefore, substantially equal to the height of the flanking lobes <NUM>, <NUM>.

Referring to <FIG>, the vessels <NUM>, <NUM>, <NUM> each include a mid-layer <NUM>, <NUM>, <NUM> that substantially covers the respective liners <NUM>, <NUM>, <NUM>. The mid-layer <NUM> is a continuous fiber wrapping wrapped about the lobes and end caps of the liners for structural strength and for distributing internal stress. The primary reinforcement (i.e., the fibers), is made of a carbon fiber. A matrix material or resin for binding the continuous fibers may include epoxy, vinyl ester and other resin systems that may be nano-enhanced. It is further contemplated and understood that the mid-layers <NUM>, <NUM>, <NUM> may be made of resin impregnated fibers.

When the pressure vessel assembly <NUM> is at least partially assembled, the interior wall <NUM> of the flanking lobe <NUM> is opposed and in proximity to the interior sidewall <NUM> of the interior lobe <NUM>. The portion of the mid-layer <NUM> covering the interior wall <NUM> may be directly adjacent and adhered to the portion of the mid-layer <NUM> that covers the sidewall <NUM> if a binder is present. Similarly, the interior wall <NUM> of the flanking lobe <NUM> is opposed and in proximity to the interior sidewall <NUM> of the interior lobe <NUM>. The portion of the mid-layer <NUM> covering the interior wall <NUM> may be directly adjacent and adhered to the portion of the mid-layer <NUM> that covers the sidewall <NUM>.

Referring to <FIG>, the pressure vessel assembly <NUM> may include an outer layer <NUM> that generally covers and envelops the mid-layers <NUM>, <NUM>, <NUM>. The outer layer <NUM> may be applied after the mid-layers <NUM>, <NUM>, <NUM> are joined. The outer layer <NUM> may be a mixture of a chopped fiber and resin that may be spray applied (i.e., spray chop fiber/resin) or may be a sheet molding compound (SMC). The primary reinforcement (i.e., the chopped fibers), may be made of a carbon fiber, a glass fiber or a aramid fiber of about one (<NUM>) inch in length (<NUM>). The resin for binding the chopped fibers may include epoxy, vinyl ester and other resin systems that may be nano-enhanced.

The pressure vessel assembly <NUM> may further include a plurality of junctions <NUM> with each junction located where respective ends of the outer walls <NUM>, <NUM>, <NUM>, ends of the sidewalls <NUM>, <NUM>, and ends of interior walls <NUM> generally meet. Each junction <NUM> may generally be Y-shaped (i.e., a three pointed star) and may be made of the same material as the outer layer <NUM>.

Because of the use of the continuous fiber in the mid-layers <NUM>, <NUM>, <NUM>, the vessel assembly <NUM> weight is much lighter than if the entire assembly were made with a chopped fiber. However, the internal structural sidewalls <NUM>, <NUM> and internal walls <NUM> have different mechanical properties from the outer walls <NUM>, <NUM>, <NUM> with the hybrid of continuous fiber and chopped fiber. The internal structural sidewalls <NUM>, <NUM> and internal walls <NUM> will have a higher modulus of elasticity than the hybrid outer walls <NUM>, <NUM>, <NUM>, and therefore the junctions <NUM> will require an optimized angle that is different from about one-hundred and twenty (<NUM>) degrees that would typically be derived from homogeneous materials. The junction <NUM> angle and the internal wall thickness will be optimized based on specific material properties.

Referring to <FIG> and <FIG>, the pressure vessel assembly <NUM> may further include an absorbent <NUM> (i.e., gas absorbent media) located in one or all of the chambers <NUM>, <NUM>, <NUM>. The absorbent <NUM> functions to supplement the gas storage capacity of the pressure vessel assembly <NUM>. The absorbent <NUM> may be in granular or pellet form, or may be formed into any desirable shape. Non-limiting examples of absorbents <NUM> may depend, at least in-part, on the type of gas being stored. For example, if the gas is hydrogen, the absorbent <NUM> may include metal organic frameworks, active carbon, metal hydrides, carbon nano tubes, and others. If the gas is CNG, the absorbent <NUM> may include activated carbon, metal organic frameworks, and others.

The pressure vessel assembly <NUM> may also include a heating element <NUM> adaptable to heat the absorbent <NUM> for improved extraction of the fluid or gas therefrom. The heating element <NUM> isbe embedded in the mid layer <NUM>. Moreover, each chamber <NUM>, <NUM>, <NUM> may contain an absorbent <NUM> and a separate heating element <NUM> may be embedded in each mid-layer <NUM>, <NUM>, <NUM>. It is further contemplated and understood, that one heating element <NUM> may heat the absorbent(s) <NUM> located in all three chambers <NUM>, <NUM><NUM>, and the single heating element may generally be embedded in the outer layer <NUM>. In yet another embodiment, one or more heating elements <NUM> may be disposed and embedded between the mid-layers <NUM>, <NUM>, <NUM> and the outer layer <NUM>.

Non-limiting examples of the heating element <NUM> include devices configured to convert electrical energy to thermal energyIn the above mentioned example where the polymer matrix composite of the mid-layers <NUM>, <NUM>, <NUM> includes a continuous carbon fiber reinforcement, the carbon fiber itself may serve as a portion of an electrical circuit that emits thermal energy. The heating element type may be based on desired characteristics such as weight, heating efficiency and cost.

In another embodiment, the composite material of the mid-layers <NUM>, <NUM>, <NUM> and/or the outer layer <NUM> may include a glass fiber for structural reinforcement, and which also functions as an electrical insulation. Moreover, the heating element <NUM> may also function as part of a vessel structural health monitoring system <NUM> capable of detecting, for example, any discontinuity or breakage of the heating elements <NUM>.

The heating elements <NUM> may be embedded in the mid-layers <NUM>, <NUM>, <NUM> during the manufacturing process of the pressure vessel assembly <NUM>. The heating elements <NUM> may be placed at an optimal depth within the layers <NUM>, <NUM>, <NUM> to maximize heating efficiency and minimize the heating element electrical load.

The composite pressure vessel assembly <NUM> may provide a lightweight storage tank with a high energy storage density. The approach enables the easy addition of reinforcing composite material where needed (e.g. junctions <NUM>). The use of the hybrid continuous and short fiber may further minimize the vessel assembly weight. Because the vessel assembly <NUM> may be in a non-cylindrical shape, the assembly will provide the highest conformability to a given space. Moreover, the composite construction will also provide corrosion resistance compared to metallic tanks.

Claim 1:
A pressure vessel assembly (<NUM>) comprising:
a first composite layer (<NUM>) surrounding at least one chamber (<NUM>); and
a first heating element (<NUM>) embedded in the first composite layer (<NUM>);
a first absorbent (<NUM>) disposed in at least one of the at least one chamber (<NUM>);
a first liner (<NUM>) defining a first chamber (<NUM>) of the at least one chamber, and wherein the first liner (<NUM>) is encompassed by the first composite layer (<NUM>).
wherein the first composite layer (<NUM>) comprises continuous carbon fibers, and the heating element (<NUM>) includes the continuous carbon fibers;
wherein the continuous carbon fibers are a portion of an electrical circuit of the assembly that is configured to emit thermal energy; and
wherein the continuous carbon fibers are wrapped about lobes and end caps of the first liner (<NUM>).