FIELD OF THE INVENTION

The present invention relates to a method for providing a transport safe device for thermal energy storage, and a device provided by means of such a 5 method.

BACKGROUND OF THE INVENTION

Current practice in providing large-scale devices for thermal energy storage include providing a sealable container having means for heating a 10 material held therein, transporting said container to the location at which the device is to be used, filling the container with a phase change material, slowly and carefully so as to not damage the protective coating commonly provided on the inner walls of the container, sealing the container, and heating the phase change material to above its melting temperature. Transporting the 15 container and the phase change material separately is a logistic challenge and a waste of logistic resources. However, prior art solutions does not allow the phase change material to be transported inside the container, as this would damage the protective coating thereof.

20 SUMMARY OF THE INVENTION

It is an object of the present invention to alleviate at least some of the mentioned drawbacks of the prior art and to provide a transport safe device for thermal energy storage that does not have to be filled with phase change material on its site of intended use, but which instead can be prefilled at its 25 site of manufacturing. This and other objects, which will become apparent in the following, are accomplished by a transport safe device for thermal energy storage and a method for providing such a device, as defined in the accompanying independent claims.

The term exemplary should in this application be understood as 30 serving as an example, instance or illustration. A device for thermal energy storage is a device that is configured to take energy in one form, e.g. electric, and heat a piece of material held in a container. The device then insulates the heated piece of material in the container such that ambient losses are reduced. When needed, the device uses the thermal energy of the piece of material, often a piece of phase change material, to generate electrical energy. Such machines are often somewhat delicate, and not safe to transport once assembled. The present invention is at least partially based on the realisation that making such devices safer to transport would increase production efficiency and device ease of use, as the phase change material can be prefilled at the site of manufacturing instead of at the site of intended usage. The present invention thus relates to a method of providing such a device that is also safe to transport from a central manufacturing site to a site of usage. The present invention does this by providing a temporary protective coating that protects the protective coating of the container from damage when transporting the device from a manufacturing site to a site of usage. Such a device may be transported in its fully assembled state to its site of intended use with a lower risk for transport damages than devices of the prior art.

According to a first aspect of the present invention, a method for providing a transport safe device for thermal energy storage is provided. The method comprises: providing at least one piece of phase change material having a PCM melting point; providing a container having a protective coating provided on the inner walls thereof, wherein said protective coating is made from a material having a protective coating melting point that is higher than the PCM melting point; providing a temporary protective coating on the at least one piece of phase change material or on the protective coating on the inner walls of the container, wherein the temporary protective coating has a melting point that is equal to or lower than the PCM melting point; and inserting the at least one piece of phase change material into the container.

It should be understood that providing the temporary protective coating on the protective coating on the inner walls of the container means that the temporary protective coating is applied on the outside of the protective coating, such that the protective coating is sandwiched between the inner wall of the container and the temporary protective coating.

In the context of the present invention, the temporary protective coating is arranged to release from the surface to which it has been attached is to when the phase change material is heated to or above its PCM melting point. The temporary protective cover does so by transitioning from a solid state at ambient temperature, to a liquid or vaporized state when heated to or above the PCM melting point.

According to one example embodiment of the present invention, the temporary protective coating is made from the same material as the at least one piece of phase change material. This means that the temporary protective coating, once heated to the PCM melting point or above, is mixed with the now molten at least one piece of phase change material.

According to one example embodiment of the present invention, the temporary protective coating is a foamed aluminium coating and the phase change material is an aluminium alloy. In other words, the temporary protective coating is a foamed aluminium coating and the phase change material of the at least one piece of phase change material is an aluminium alloy. Having foamed aluminium coating as a temporary protective is beneficial since the degree to which the container can be filled with phase change material when assembled is increased when also the temporary protective coating is made from the phase change material. Also, foamed aluminium has a cushioning effect between the at least one piece of phase change material and the inner walls of the container. It should be understood that an aluminium alloy is an alloy in which aluminium is the predominant metal.

According to one example embodiment of the present invention, the temporary protective coating is a foamed metal coating and the phase change material is an alloy from the same metal as the foamed metal alloy.

According to one example embodiment of the present invention, the temporary protective coating is a polymer coating having a depolymerisation temperature that is equal to or lower than the PCM melting point. This means that the temporary protective coating changes from a solid state at ambient temperature, to a vaporized state when heated to the PCM melting point or above. When heated to the PCM melting point or above, complete or partial combustion of the polymer coating occurs. Thus, the temporary protective coating releases and any combustion gases produced thereby may be vented out from the container.

According to one example embodiment of the present invention, the temporary protective polymer coating is arranged such that when reaching its depolymerisation temperature, residue from the depolymerized temporary protective polymer coating is deposited onto the protective coating of the container, wherein said residue decreases the permeability of the protective coating of the container by filling the pores thereof. A material with pores may be called a pours material. A pore is a void in the material.

According to one example embodiment of the present invention, a heat activated protective coating is provided, said heat activated protective coating being laminated to either the protective coating of the container or to the temporary protective coating. The heat activated protective coating has a depolymerisation temperature that is higher than the PCM melting point, such that an extra film or coating is provided that does not vaporize but binds to the protective coating when activated by the heat from the phase change material.

According to one example embodiment of the present invention, the method further comprising providing means for heating the at least one piece of phase change material to the PCM melting point or higher.

According to one example embodiment of the present invention, the method further comprises heating the at least one piece of phase change material to the PCM melting point or higher, whereby the temporary protective coating releases from the at least one piece of phase change material or from the protective coating on the inner walls of the container.

According to one example embodiment of the present invention, the temporary protective coating covers at least the part of the surface of the at least one piece of phase change material that would be in contact with the inner walls of the container, once the at least one piece of phase change material is inserted thereinto. According to one example embodiment, wherein the at least one piece of phase change material is a single piece of phase change material, and wherein the temporary protective coating is a webbed or perforated coating on which the single piece of phase change material may rest once inserted into the container.

According to one example embodiment, wherein the at least one piece of phase change material is a single piece of phase change material, and wherein the temporary protective coating is a plurality of support cushions provided interspersed between the single piece of phase change material and the inner walls of the container.

According to one example embodiment of the present invention, the method further comprising sealing the container with the at least one piece of phase change material inside. In other words, the method may comprise sealing the container when the at least one piece of phase change material is arranged inside the container. The sealed container thus is partially filled with phase change material, above which a container headspace is provided.

Sealing the container may for example be done by means of a permanent or semi-permanent lid or a temporary cover. Thus, the inside of the container and the phase change material held therein is protected from debris entering during transportation of the device.

According to one example embodiment of the present invention, the method further comprising providing a controlled environment inside said container. Specifically, the method further comprises providing a controlled environment inside the container headspace formed when the container is sealed with the phase change material held therein.

Providing a controlled environment means that means are taken to ensure that the container headspace contains a predetermined mixture of gases at a predetermined pressure and temperature. The specific composition and conditions characterizing such a controlled environment are well-known to the skilled person and varies depending on the type of phase changes material used in the device. The purpose of the controlled environment is to reduce unwanted reactions between the phase change material and the gases in the container headspace. However, the actual provision of such a controlled environment in the method described herein forms part of the inventive concept.

According to one example embodiment of the present invention, the controlled environment is provided by means of venting a portion of the gas inside the container headspace through an outlet vent, and filling said container headspace with a control gas through an inlet vent. The purpose of having the controlled environment is to reduce the risk of oxidation or other unwanted reactions of the heated phase change material with ambient air.

According to one example embodiment of the present invention, the controlled environment is provided by venting at least a portion of a gas in the container headspace and replacing the vented gas with a control gas. This is done by means of venting a portion of the gas inside the container headspace through an outlet vent, and filling said space with a control gas through an inlet vent. The purpose of the control gas is to reduce the risk of oxidation or other unwanted reactions of the heated phase change material with ambient air.

According to one example embodiment of the present invention, the at least one piece of phase change material is a single piece of phase change material having an outer shape and size that substantially corresponds to an inner shape and size of the container.

According to one example embodiment of the present invention, the at least one piece of phase change material is a granular phase change material. This simplifies both the initial filling of the container with phase change material, and the subsequent refilling of phase change material once the initial filling has been heated to or above the PCM melting point. The granular phase change material may for example be a plurality of metal spheres, poured through an opening in the container such that the space therein is at least partially filled with phase change material.

According to the second aspect of the present invention, a transport safe device for thermal energy storage is provided. The device comprises: a container; at least one piece of phase change material having a PCM melting point, said at least one piece of phase change material being arranged inside said container; a protective coating provided on the inner walls of said container, wherein said protective coating is made from a material having a protective coating melting point that is higher than the PCM melting point; and a temporary protective coating provided on the at least one piece of phase change material or on the protective coating on the inner walls of the container, wherein the temporary protective coating has a melting point that is equal to or lower than the PCM melting point.

Generally, all terms used in the description are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will now be further clarified and described in more detail, with reference to the appended drawings showing different embodiments of a transport safe device for thermal energy storage and a method for providing such a device, all according to the present invention.

Figure 1a is a schematic view showing the provision of a transport safe device for thermal energy storage, wherein the temporary protective coating is provided on the outside of a single-piece phase change material that is inserted into the container,

Figure 1b is a schematic view showing a further step of the method illustrated in Figure 1a, wherein the container is sealed,

Figure 1c is a schematic view showing a further step of the method illustrated in Figure 1a, wherein the phase change material is heated to the PCM melting point and the temporary protective coating releases from the phase change material,

Figures 2a-c illustrate the method according to another example embodiment, wherein the temporary protective coating is provided on the protective coating of the inner walls of the container, Figures 3a-c illustrate the method according to another example embodiment, wherein the phase change material consists of three pieces that jointly conform to the shape of the container in which they are inserted, and wherein the temporary protective cover is provided on the outside of the three pieces of phase change material,

Figures 4a-c illustrate the method according to another example embodiment, wherein the phase change material is a granular phase change material, and wherein more phase change material is added to the container once sealed and the initial batch of phase change material has been heated to or above the PCM melting point.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, some embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention.

Figure 1a is a schematic view showing the provision of a transport safe device 1 for thermal energy storage. The device 1 comprises a container 10 for holding a piece of phase change material 20, and a single-piece phase change material 20 that is to be inserted into the container 10. The phase change material 20 has an outer shape and size that substantially corresponds to an inner shape and size of the container 10. Furthermore, the phase change material 20 has a PCM melting point at which the phase change material 20 transitions from a solid state, at which it is at room temperature, to a liquid state at the operating temperature of the device 1. Fig. 1a shows the phase change material 21 being inserted into the container 10. The device further comprises a protective coating 11 provided on the inner walls 12 of the container 10. The protective coating 11 is made from a material that has a protective coating melting point that is higher than the PCM melting point. This means that when the device 1 maintains the phase change material 20 at the operating temperature of the device 1 , which is above the PCM melting point but below the melting point of the protective coating 11 , the protective coating 11 of the container 10 remains in a solid state and protects the inner walls 12 of the container 10 from the heated phase change material 20.

The device 1 further comprise a temporary protective coating 30 provided on the single-piece phase change material 20. The temporary protective coating 30 has a melting point that is equal to or lower than the PCM melting point, such that when the phase change material 20 is heated to or above its melting point, the temporary protective coating 30 releases therefrom. The temporary protective coating 30 is provided on the outside of the single-piece phase change material 30 before the latter is inserted into the container 10, and is arranged such that it covers the part of the outer surface of the phase change material 20 that would be in contact with the protective coating 11 on the inner walls 12 of the container 10, once the phase change material 20 is inserted thereinto. Thus, the container 10 and the protective coating 11 thereon are both protected from damage caused by the phase change material 20 being inserted into the container 10 and moving around thereinside, for example during transportation of the device 1.

The device 1 further comprises means 13 for heating the phase change material 20 to the PCM melting point or higher. The skilled person readily understands that the means 13 for heating the phase change material 20 may be realized in a number of different ways, depending in part on which phase change material is used.

Figure 1b is a schematic view showing a further step of the method illustrated in Figure 1a, wherein the container 10 is sealed with the phase change material 20 inside. Here, a lid 14 has been connected to the opening of the container 10, such that the phase change material 20 is enclosed therein. The lid 14 is provided with an inlet 15 and an outlet 16, through use of which the atmosphere in the container headspace 17 may be controlled. Figure 1c is a schematic view showing a further step of the method illustrated in Figure 1a, wherein the phase change material 20 has been heated to the PCM melting point and the temporary protective coating 30 has released from the phase change material 20 and evaporated. Here, the evaporated temporary protective coating 30 may be removed from the container headspace 17 by replacing the air therein with a control gas.

Figures 2a-c illustrate the method according to another example embodiment. Here, the temporary protective coating 30 is provided on top of the protective coating 11 of the inner walls 12 of the container 10, instead of on the piece of phase change material 20. Other than this, the method illustrated in Figs. 2a-c share the same features as the method illustrated in Figs. 1a-c.

Figures 3a-c illustrate the method according to another example embodiment, wherein the phase change material 20 consists of three pieces that jointly conform to the shape of the container 10 into which they are inserted, and wherein the temporary protective cover 30 is provided on the outside of the three pieces of phase change material 20. Also, the temporary protective coating 30 covers all sides of the pieces of phase change material 20. However, this is not necessary and a partial coverage such as that illustrated in Figs. 1a-c may also be envisioned. Other than this, the method illustrated in Figs. 3a-c share the same features as the method illustrated in Figs. 1a-c.

Figures 4a-c illustrate the method according to another example embodiment, wherein the phase change material 20 is a granular phase change material, and wherein more phase change material 20 is added to the container 10 once the latter is sealed and the initial batch of phase change material 20 has been heated to or above the PCM melting point. The top-up of phase change material 20 may for example be done through an inspection or maintenance hatch 18 provided in the lid 14. Here, the temporary protective coating 30 is provided on top of the protective coating 11 of the inner walls 12 of the container 10, instead of on the phase change material 20. Other than this, the method illustrated in Figs. 4a-c share the same features as the method illustrated in Figs. 1a-c. The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. The features of the described embodiments may be combined in different ways, and many modifications and variations are possible within the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.