WO2022259274A1

WO2022259274A1 - Multi-chamber anti-sloshing tank and method for manufacturing such tank

Info

Publication number: WO2022259274A1
Application number: PCT/IT2022/050151
Authority: WO
Inventors: Sara MANTOVANI; Alessandro Ceruti
Original assignee: Universita' Degli Studi Di Modena E Reggio Emilia; Alma Mater Studiorum - Universita' Di Bologna
Priority date: 2021-06-07
Filing date: 2022-05-31
Publication date: 2022-12-15
Also published as: IT202100014777A1

Abstract

An anti-sloshing tank (1) is described, of the type comprising an external shell (2) and an internal structure (3), the internal structure (3) being such as to divide the internal volume of the tank (1) into at least two volumes (V1, V2), wherein the volumes (V1, V2) are independent and are not communicating with each other, and the internal structure (3) includes in the whole internal volume, or in part of it, a repetition along all three spatial directions of an elementary cell (4) of the Triple Periodic Minimum Surface, TPMS, type. A method for manufacturing this tank is also described.

Description

MULTI -CHAMBER ANTI -SLOSHING TANK AND METHOD FOR MANUFACTURING SUCH TANK

The present invention refers to a multi chamber anti-sloshing tank under pressurized or unpressurized conditions designed for the storage and transport of multiphase substances (liquids, gases, solids or mixtures) with an internal structure based on Triply Periodic Mimimal Surface (TPMS) cells, an example of which is represented by the gyroid typology, and to a method for manufacturing such tank.

TPMS are structures characterized in that they are periodic due to rotational symmetry planes, and are defined in differential geometry as locally with minimal surface. Sloshing, also called flapping, is a phenomenon that can be defined as the agitation of a fluid in its container, caused by accelerations exerted to the container itself. These accelerations can be caused by an earthquake or, in case of vehicle fuel tanks, by the accelerations of the vehicles themselves, whether they are land, sea or air vehicles. This is obviously a negative phenomenon that must be countered because the agitation of the fluid causes additional stresses on the tank walls that can become critical when for instance a natural frequency of vibration of the tank is matched. If the tank is open, the sloshing can lead to an overflow, or a spill, of the substances contained therein.

Furthermore, the dynamics of the means of transport can be modified by the phenomenon of sloshing of fluids inside the containers, for example fuel inside the tank or fluids inside the radiator. This effect alters the stability performance of an aircraft or of a land or naval vehicle, such as a braking or sudden acceleration of cars, especially high-performance sports cars and racing cars. In addition, trucks and/or trailers for the transport of fluids or loose substances may, in the event of braking manoeuvre, undergo dangerous dynamic phenomena due to the sudden movement in the traveling direction of the contents inside the tank, thus altering the braking distance.

To counteract and limit this phenomenon, for example, bulkheads/ribs can be used to compartmentalize the initial volume. Sometimes, the subdivision is such that each chamber does not communicate with the adjacent ones, thus requiring dedicated venting/loading and unloading systems for the substances contained. Documents WO-A1-2020/229692 and US-A1-

2020/299006 describe prior art reservoirs and methods. Moreover, the presence of two separate chambers could be exploited to store two different substances: in case of damages, the physical structure of the container favours the mix of the substances, so that one of the such substances could inhibit the harmful effect of the other one. Also, one of the substances could be self-repairing, so that in case of accident the leak of one substance is inhibited by the sealing action of the other one which eventually could change its physical state (e.g. from fluid in pressure to solid) . Finally, the internal structure based on TPMS could show crashworthiness properties and improved thermic exchange features.

Object of the present invention is at least partially overcoming the above-described prior art drawbacks through an anti-sloshing tank with multiple chambers for the storage and/or transport of multiphase substances (liquids, gases, solids or mixtures) with a safety effect in case of accidents.

The above and other objects, as will be explained below, are achieved with an anti sloshing tank according to claim 1, of the type comprising an external shell and an internal region fully or partially filled by the repetition of TMPS lattice cells, the internal structure thereby being such as to divide the internal volume (or part of it) of the tank into at least two volumes (VI, V2), wherein the internal structure comprises a repetition in the three directions of the space of an elementary cell of the TPMS type, for example a gyroid.

To reduce the increase of volume respect to a one-volume configuration of the recipient, only a portion of it (e.g. the sides and the bottom) could be based on TMPM. In this latter case, a set of walls divides the internal part of the recipient filled with TPMS from the void part of the container.

The external shell can be manufactured as a monolithic skin and/or a sandwich panel which is obtained by at least three layers where the inner core is obtained by TMPS itself.

The method for manufacturing the anti sloshing tank includes additive technologies such as 3D printing and/or stereolithography.

Preferred embodiments and non-trivial variantions of the present invention are the subject matter of the dependent claims.

It is understood that all attached claims form an integral part of the present description.

The finding according to the invention solves the above drawbacks since, with the use of TPMS structures, such as gyroids, it is possible to divide the volume inside the tank (or a part of it) into at least two distinct non-communicating volumes; this feature has two important consequences.

Firstly, the labyrinth of channels inside the tank is such as to dampen the motion of the fluids (anti-sloshing) in the event of dynamic and/or impulsive stresses.

Secondly, if the two volumes are not made communicating through the creation of special passages, it is possible to fill one chamber with a substance and the other chamber with another substance, even with another phase and a chemical-physical nature. A recipient where the TPMS structure is applied only in certain zones is included in the possible embodiments.

As an example of filling the tank with two different substances, consider the transport of a flammable liquid and an agent that acts as an extinguishing agent. In case of a racing car, in particular a

Formula 1 car, the container could represent a tank in which an extinguishing fluid is transported in addition to fuel. In this case, the anti-sloshing characteristics would help in the dynamics of the car when cornering and when braking; furthermore, in the event of an accident, there would be a gradual release of the fuel and mixing with the extinguishing fluid.

Another application case of filling with two different substances can be, for example, a viscous food substance and another substance capable of absorbing it in case of damage to the container. In the event of an accident, the soiling of the roadway would be greatly reduced.

A further application of the adoption of different substances might lead, for instance, to a self-repair of the tank when a sudden and undesired failure occurs. If one of the substances is able to change phase (from gas/liquid/plasma to solid) as a reaction with the external environmental conditions at which the tank works, i.e., temperature, humidity, concentration of oxygen, carbon dioxide and nitrogen.

Furthermore, with an appropriate choice of the size of the unit cell of the internal structure, for example gyroid, important advantages are obtained in the event of an accident. Other possible examples of application regard the use of such a recipient structure in batteries or other energy storage system, where potentially harmful substances are carried.

Firstly, the graduality of the release of the transported substance can be adjusted. In fact, the internal structure with repeated cells ensures that the path that the substance must follow in order to escape from the damaged area of the tank is very tortuous. It follows that the smaller the unit cell, the more gradual the release will be. These properties can be adopted in for the minimization of the leakage of electrolyte from the battery pack mounted on full electric or hybrid vehicles.

Secondly, the release of the transported substance occurs simultaneously with the release of the other transported substance, with high miscibility of the two substances. This fact leads, for example, to an improvement in the absorbent action on the road surface or in the extinguishing action for flammable fluids.

The solution of the simultaneous transport of fuel and extinguishing fluid can be advantageously used both for trucks employed for the transport of the fuels, and for the tanks of the vehicles themselves.

Also in aerospace applications (airplanes, helicopters, space vehicles), there is an advantage in the compartmentalization of the tanks by means of TPMS structures, for example gyroids.

The use of these structures inside the tanks also allows increasing the structural strength and the stability of the tank itself, of its outer walls and/or internal ribs it obtains by sandwich panels with TPMS core.

A safety and anti-sloshing effect could be achieved applying the invention to fuel recipients in aircraft, helicopters, space vehicles, provided that with fuel not only fossil fuels are intended, but also hydrogen, bio-fuels, and substances used in batteries and electric energy storage. In this case, the TPMS structure allows not only anti-sloshing and safety to the recipient, but also structural properties: one possible embodiment of this could relate the use of TPMS structure in a wing where fuel is stored. It is worth noting that the release of two substances in case of accidents could be also used in the case where one of the fluids shows sealing properties when exposed to the external environment: in this case, the leak of one substance in case of damages to the recipient is reduced or interrupted by the effect of the second substance stored.

As for the method for manufacturing tanks according to the invention, the use of TPMS structures, such as gyroids, means that no manual work is required once the gyroid structure has been produced. This advantage is found both in the stand-alone structure and in the one placed inside the tank, with division of its total capacity into smaller but mutually connected volumes.

The anti-sloshing tank according to the invention also has an important use for containing water, where the presence of the already described internal structures would reduce the dynamic effects in the event of earthquakes. Furthermore, one of the two chambers could be used for absorbent substances in order to avoid the spillage of liquid, for example water, in case of breakage of the tank itself. The above also applies to silos (for example for the storage of semi-finished products from ceramic production such as glazes and slips or plastic materials) in case of seismic stresses. The present invention will be better described by some preferred embodiments thereof, provided by way of non-limiting example, with reference to the attached drawings, in which: - FIG. 1 shows an anti-sloshing tank according to the present invention, with a solid outer skin and fully filled by TMPS structures;

- FIG. 2 shows an elementary cell of the TPMS type, in particular a gyroid; - FIG. 3 shows a TPMS-type multiple cell structure, in particular a gyroid; and

- FIG. 4 to 7 show embodiments of a case in which not only all of the structure of the recipient is filled with TPMS, but only in the sides and bottom of the recipient itself.

With reference to FIG. 1, (1) designates a tank consisting of an external shell (2) and an internal structure (3), given by the repetition in the three spatial directions of an elementary cell (4) of the gyroid type.

FIG. 2 shows the elementary cell (4), of the gyroid type, of the internal structure (3).

FIG. 3 shows how the particular repetition of

11

SUBSTITUTE SHEETS (RULE 26) the elementary cells (4) defines a structure (3) featuring the creation of two volumes (VI, V2) separated from each other. The cells can follow both a conformal and a non-conformal filling design within the tank. In fact, all tunnels designated with (VI) are in mutual communication, as are all tunnels designated with (V2), but there is no connection between these volumes (VI) and (V2). It therefore follows that the reservoir (1), thanks to the properties of the gyroid-type cells (4), has two independent chambers (VI, V2) that are not in communication with each other; in this way, it is possible to fill a first chamber (VI) with a substance and a second chamber (V2) with another substance, also in another phase and/or of another chemical-physical nature.

Obviously, the two volumes (VI) and (V2) can be put into communication by opening one or more passages between the tunnels (VI) and (V2). This is done in case of transport of a single fluid with exclusive anti-sloshing function.

The size of the unit cell (4) can be defined as specified by the designer, on the basis of the desired characteristics and the technology to be used for the construction of the tank (1) itself.

More in detail, the gyroid structures (3), like all TPMS structures, are based on the repetition of an elementary cell (4) in the three spatial dimensions. The properties of these structures are useful to give rise to structures of continuous curvature by joining elementary cells (4) (of equal or variable dimensions depending on the application), and to obtain a self-supporting structure that does not require the use of support material.

TPMS structures, in this case gyroids, can now be obtained exclusively through additive technologies, such as 3D printing or stereolithography, and in this case the properties of these structures cancel or minimize the use of support structures. However, it should be borne in mind that the use of cell shapes other than TPMS could still lead to the need for the use of support structures that must be eliminated from the printed part with a manual process that takes time and increases component costs and material waste. FIG. 4 to 7 show embodiments of a case in which the TPMS structure is applied only in certain parts of the recipient, and walls are used to obtain anyway two separate chambers, where one is larger respect to the other because of a zone without TPMS structures.

Only a layer (5) around the side and low part of the tank (1) is filled with TPMS structures. A set of thin walls (6) are introduced so that the void part (7) of the tank (1) is connected to only one of the two volumes that are obtained with TPMS structures. Eventually, one or more sheet bulkheads with holes (8) can be applied in the void part (7) to reduce the sloshing. Possible embodiments of the invention include the use of a core of TPMS and sides with walls for the bulkheads (9), or a combination of TPMS- based bulkheads (9) and sheet bulkheads (8).

The internal, void part (7) of the tank (1) is not filled with TPMS, and it is in contact only with one of the two volumes in which TPMS structures splits the layer (5) of the tank (1). In this way, two separates volumes are obtained, one of which includes the void part (7), so that

14

SUBSTITUTE SHEETS (RULE 26) its volume is larger than the other one which corresponds to only half of the tank volume (5) filled with TPMS. In this volume there is no need to double the volume of the tank (1) to store a quantity of substances, but lower increases in volume can be achieved.

Furthermore, in case of areas which are either partially or completely inaccessible, it is impossible to eliminate the support material which therefore affects the final mass of the component, not substantially improving its mechanical response.

The tank (1) is self-supporting and in case of production through other additive technologies, such as 3D printing, does not require support material (except as noted above for cells whose shape is different from TPMS), thus reducing the costs of raw materials and post-production phases. The internal TPMS structure (3) can be obtained either integrally with the external shell (2) of the container, by means of additive technologies, or on the other hand as a structure to be inserted and connected to the external shell produced with another technology. The TPMS structure (3) will in any case be produced with the additive technologies.

Due to the nature of the internal structure (3) with multiple chambers which are not mutually communicating, the system is characterized by a significant secondary effect concerning the thermal management of the tank (1). It can be used for refrigeration and/or heating of the fluids or solids present in the container, simply by placing, for example, a substance to be heated (or refrigerated) in the first chamber (VI) and manufacturing a heating (or refrigerating) fluid pass through the second chamber (V2). Faced with a limited increase in the mass of the tank, due to the housing of TPMS structures inside the tank itself, the phenomenon of sloshing is greatly reduced. Furthermore, these internal structures induce an increase in the structural resistance of the tank itself, not least to phenomena such as seismic events.

In fact, these families of cells are designed to absorb the energy that is transferred to the structure following an impulsive event, and improve the response of the system with a typically gradual and controlled collapse.

Furthermore, the resistance to internal pressure is significantly increased, since the tank walls are well supported by the TPMS structure, for example a gyroid.

Claims

1. Anti-sloshing tank (1), of a type comprising an external shell (2) and an internal structure (3), the internal structure (3) being such as to divide an internal volume of the tank (1) into at least two volumes (VI, V2), characterized in that the volumes (VI, V2) are independent and are not communicating with each other, and that the internal structure (3) comprises a repetition along all three spatial directions of an elementary cell (4) of a Triple Periodic Minimum Surface, TPMS, type.

2. Anti-sloshing tank (1) according to claim 1, characterized in that the volumes (VI, V2) are filled with substances of different nature.

3. Anti-sloshing tank (1) according to at least one of claims 1 to 2, characterized in that the elementary cell (4) of the Triple Periodic

Minimum Surface type is like a gyroid.

4. Anti-sloshing tank (1) according to at least one of claims 1 to 2, characterized in that the periodical structure is applied only to a part of the recipient, and a set of walls allows to obtain two separate volumes, where one is larger than the other one.

5. Anti-sloshing tank (1) according to any one of the preceding claims, characterized in that only a layer (5) around the side and low part of the tank (1) is filled with TPMS structures, a set of thin walls (6) being introduced so that the void part (7) of the tank (1) is connected to only one of the two volumes that are obtained with TPMS structures.

6. Anti-sloshing tank (1) according to claim 5, characterized in that one or more sheet bulkheads with holes (8) are applied in the void part (7) to reduce the sloshing.

7. Anti-sloshing tank (1) according to claim 6, characterized in that it uses a core of TPMS and sides with walls for the bulkheads (9), or a combination of TPMS-based bulkheads (9) and sheet bulkheads (8).

8. Road vehicle or air vehicle or space vehicle comprising a tank according to any one of the preceding claims, with an internal structure, or part of it, based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, one of which containing a flammable liquid and the other an extinguishing substance, with antisloshing properties.

9. Road vehicle or air vehicle or space vehicle comprising a tank according to any one of claims 1 to 7, with an internal structure, or part of it, based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, one of which containing a viscous substance, and the the other a substance capable of absorbing the former, with anti-sloshing properties .

10. Road vehicle or aeronautic or space vehicle comprising a tank according to any one of claims 1 to 7, with an internal structure based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, one of which containing a substance with sealing properties if exposed to the external environment, and another substance whose leak is inhibited by the fist substance.

11. Energy storage recipient according any one of the claims 1 to 7, with internal structure, or part of it, based on TPMS, produced by Additive

Manufacturing techniques, with two independent chambers, with anti-sloshing properties.

12. Water tank comprising a tank according to any one of claims 1 to 7, with internal structure based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, with antisloshing properties.

13. Silos for the storage of semi-finished products, comprising a tank according to any one of claims 1 to 7, with an internal structure based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, with antisloshing properties.

14. Vessel or tank under pressure for one or more non-hazardous fluids, comprising a tank according to any one of claims 1 to 7, with internal structure based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, with antisloshing properties .

15. Pressurized vessel or tank for one or more antagonist fluids, comprising a tank according to any one of claims 1 to 7, with internal structure based on TMPS, produced by Additive Manufacturing techniques, with two independent chambers, with antisloshing properties

16. Method for manufacturing an anti-sloshing tank (1), of a type comprising an external shell (2) and an internal structure (3), the internal structure (3) being such as to divide the internal volume of the tank (1) into at least two independent volumes (VI, V2), characterized in that the internal structure (3) includes a repetition along all three spatial directions of an elementary cell (4) of a Triple Periodic Minimum Surface, TPMS, type, and in that the method comprises additive technologies, such as 3D printing and/or stereolithography.

17. Method for manufacturing an anti-sloshing tank (1) according to claim 16, characterized in that it provides for the assembly of an external shell (2) with the internal structure (3).

18. Method for manufacturing an anti-sloshing tank (1) according to claim 16, characterized in that the internal multiple-cell structure (3) is of the gyroid type.

19. Method for manufacturing an anti-sloshing tank (1) according to claim 18, in which one of the substances changes phase, from liquid or plasma or gas to solid, when interacts with the outer environmental conditions for a leakage of the tank itself, this change of phase of the substance contained in the system inducing a safe and self-repairing condition.