Inventor: Peter Franz HORWATH

Cross-Reference to Related Application

None

Technical Field

The disclosed embodiments are in the field of phase change materials, and particularly disclose methods and systems for producing phase change material products.

Background of the Art

The use of phase change material (PCM) to cool and heat air is well known in the art. PCM is a material which changes from one phase (e.g. liquid) to another phase (e.g. solid) at a specific transition temperature. PCM’s have a high heat of fusion, and as such are capable of absorbing and releasing large amounts of energy.

PCMs absorb heat from the environment when they“melt” (liquefy), and release heat into the environment when they“freeze” (solidify). PCMs can therefore serve as a temperature moderator which reduces temperature extremes. PCMs are available with a phase change temperature in the human comfort zone (e.g. around 75° F (24°C)).

PCMs are available with a variety of chemical compositions and transition temperatures, as is well known in the art. For example, inorganic/mineral based PCMs such as salt hydrates use salt, clay, and water mix normally consisting of calcium chloride among other salt/chemical

combinations. The transition temperatures of common salt hydrate PCM’s are - 45°F (7.2°C), 55°F (12.8°C), 65°F (18.3°C), 71°F (21.7°C), 73°F (22.8°C), and 78°F (25.6°C). Other types of PCMs are organic materials, petroleum or plant based, and use oils/waxes such as paraffin, palm oil, fatty esters etc.

Sheets, coatings, and products containing phase change materials have been used for years to increase comfort, reduce energy consumption, reduce temperature swings for buildings, packaging, and provide energy storage. Phase change materials (PCMs) absorb heat as they melt, changing phase from solid to liquid; and release heat as the material begins to freeze back to a solid state. Because PCMs transition for solid to liquid and back during normal use, the PCMs must be contained within the product to prevent leaking during the liquid phase. Currently manufactures of these products use expensive, complex processes such as micro encapsulation, self-encapsulation, and macro encapsulation to contain the PCMs. These processes are expensive, degrade the thermal properties of the PCMs, and limit the applications of these materials.

Summary

The present disclosure teaches methods and systems for making phase change material products. The embodiments eliminate the necessity for pre-encapsulation of the phase change material pieces by using a medium itself as the encapsulate. This can be accomplished by performing mixing, forming, and curing processes at temperatures below the transition temperature of the phase change materials used, thereby allowing the phase change materials to be handled in the solid phase and encapsulated by the medium used in the process.

Methods disclosed provide a low cost process of integrating phase change materials into products without the need for micro encapsulation, macro encapsulation, or self-encapsulation. This can be done in a manufacturing line process, as an addition to a casting product, or as an applied coating done within or outside of a manufacturing environment.

In one embodiment, the process is as follows:

1. A phase change material is brought to a temperature below the melting temperature of the PCM and formed into the desired shape for inclusion into the final product. In some cases the process would include cutting or grinding the frozen PCM to form PCM pieces of the correct size. However, the product may be precast to the desired shape prior to freezing.

2. The PCM pieces are mixed with a medium while the medium is below the PCM melting temperature and the medium is in its liquid state. In other words, the medium is a substance which surrounds the PCM pieces to form a slurry mixture.

3. The combined mixture is formed (shaped) through any of multiple forming processes to the desired final shape. These processes could include but are not limited to: cold forming, extruding, roll forming, etc.

4. The final product is allowed to cure (the medium solidify) at a temperature below the melting temperature of the phase change material. This temperature could be maintained by:

keeping the environment below the temperature, by active cooling of the manufacturing surfaces, by addition of an evaporating component which would remove heat, by an endothermic reaction, or another method. Curing maybe by any method including UV activation, solvents, or any other method to transition to a solid state.

Other embodiments, in addition to the embodiments enumerated above, will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the method and system for making phase change material products.

Brief Description of the Drawings

The inventive aspects of the following disclosure will be best understood when reference is made to the appended drawings and the detailed description thereof, in which identical parts are identified by identical reference numbers and wherein:

FIG. l is a side elevation view of a schematic depiction of an embodiment of a system for making phase change material products;

FIG. 2 is an enlarged view of area 2 of FIG. 1;

FIG. 3 is an enlarged view of area 3 of FIG. 1;

FIG. 4 is a perspective view of a phase change material product;

FIG. 5 is an enlarged side elevation view of a first layer of medium;

FIG. 6 is an enlarged side elevation view of a phase change material product disposed on the first layer of medium;

FIG. 7 is an enlarged side elevation view of a second layer of medium disposed on the phase change material product;

FIG. 8 is a side elevation view of a sealed phase change material product;

FIG. 9 is a side elevation view of a schematic depiction of a second embodiment of the system for making phase change material products;

FIG. 10 is a side elevation view of a schematic depiction of a third embodiment of the system for making phase change material products;

FIG. 11 is an enlarged top plan view of a tool which is an extrusion die;

FIG. 12 is an enlarged perspective view of a mass of phase change material being ground to form pieces of phase change material;

FIG. 13 is an enlarged view of a compressible material added to a mixture of phase change material pieces and a medium; and, FIG. 14 is an enlarged view of a porous material added to a mixture of phase change material pieces and a medium.

Detailed Description

Referring initially to FIG. 1, there is illustrated a side elevation view of a manufacturing system for making phase change material products, the system generally designated as 20. FIG. 2 is an enlarged view of area 2 of FIG. 1, and FIG. 3 is an enlarged view of area 3 of FIG. 1. System 20 includes pieces of phase change material 22 which have a transition temperature, the pieces of phase change material 22 being in a solid (“frozen”) phase. Depending upon the application, the pieces of phase change material 22 may be of sizes ranging from a fine powder to chunks having a maximum dimension of one inch or more. The shape of the pieces of phase change material 22 may be irregular as shown, or may be pellets, grains, spheres, strings, rods, fibers, or any other useful form.

The pieces of phase change material 22 may be formed by grinding, shaving, shredding, cutting, extruding, casting, pelletizing, or the like (refer to FIG. 12 and the associated discussion for one embodiment). The pieces of phase change material 22 are keep in the solid phase by maintaining the surrounding environment at a temperature which is below the transition temperature of the pieces of phase change material 22. This may be accomplished by controlling the

temperature of (1) the ambient air, (2) the working surfaces which contact the pieces of phase change material 22, (3) the medium (see discussion below), (4) the tool (see discussion below), or a combination of these.

System 20 further includes a medium 24 which is transformable from a liquid state to a solid state, the medium 24 initially being in the liquid state and at a temperature which is below the transition temperature of the pieces of phase change material 22. While in the liquid state, medium 24 is configured to combine with the pieces of phase change material 22 to form a mixture 26 (i.e. a slurry of pieces of phase change material 22 and medium 24). The mixing is performed in a vessel 28. Later, the medium 24 may be transformed to the solid state and thereby encapsulate the pieces of phase change material 22. Medium 22 may be a polymer, epoxy, resin, paint, or the like which is in the liquid state when mixed with the pieces of phase change material 22, and may then be permanently transformed to the solid state by UV activation, solvent evaporation, drying, or the like. System 20 further includes a tool 30 which is configured to receive mixture 26 and form (create) a phase change material product 32 of a desired shape and size. That is, tool 30 may be any device which is designed to form a phase change material product 32 from mixture 26 (e.g. tool 30 may be a roller, a sprayer, a mold, a container, a bag, a brush, a pouring vessel, a die, an extrusion die, etc.). In an embodiment, tool 30 is at a temperature which is below the transition temperature of the pieces of phase change material 22. Phase change material product 32 may be a panel, a sheet, a film, a coating, strands, fibers, a casting, or any other desired shape. In the shown embodiment, phase change material product 32 is a sheet, and tool 30 includes a roller which is configured to roll mixture 26 into the sheet. The shown embodiment also includes a movable support surface 34 which receives mixture 26 and moves toward tool 30. Movable support surface 34 rolls on rollers 35. In the shown embodiment, after rolling mixture 26 into a sheet, a UV light 36 transforms (cures) the medium 24 of mixture 26 to the solid state, thereby resulting in a sheet of pieces of phase change material 22 surrounded by solid state medium 24. Phase change material product 32 may also be sealed to prevent leakage of liquid phase change material 22 (refer also to FIGS. 5-8 and the associated discussions). After the medium 24 has been transformed to the solid state, phase change material product 32 may be raised to a temperature above the transition temperature.

Referring to FIGS. 2 and 3, in mixture 26 the weight percent of pieces of phase change material 22 may vary depending upon the application (e.g. 10% - 90%). In an embodiment the weight percent of pieces of phase change material 22 in mixture 26 is at least 50%.

FIG. 4 is a perspective view of a phase change material product 32. In the shown embodiment phase change material product 32 is a sheet comprising pieces of phase change material 22 encased in solid medium 24.

FIGS. 5-7 illustrate a sequence of sealing mixture 26 with two layers of medium 24 to form a sealed phase change material product 32. That is, phase change material product 32 includes a layer of mixture 26 sandwiched between first and second layers of medium 24. Each layer is sequentially deposited. Sealing prevents pieces of phase change material 22 from leaking due to expansion (refer also to FIG. 13 and the associated discussion). In an embodiment the medium 24 of each layer is transitioned to the solid state prior to the application of the next layer. In the shown embodiment, a support surface 34 is used to hold the layers during construction. The sealing may be performed using the apparatus of FIG. 1, or the medium 24 may be painted, sprayed, or applied in any other effective manner.

FIG. 8 is a side elevation view of a sealed phase change material product 32. A sealer 38 seals phase change material product 32 to both protect the product and prevent phase change material leaks. Sealer 38 may be a paint, a layer of polymer or other material, a layer of medium, or any other covering which will seal and protect phase change material product 32. Sealer may be applied by any useful means such as by spraying, with a brush, wiped, poured, etc.

FIG. 9 is a side elevation view of a second embodiment of the system for making phase change material products 32, the system generally designated as 120. Pieces of phase change material 22 are combined with a medium 24 in a vessel 28. The resulting mixture 26 is transferred to a tool 30 which in this instance is a sprayer which is configured to spray mixture 26 onto an article 500 (such as the shown thin sheet) to form a coating on the article 500. In this embodiment the phase change material product 32 is the coating which is applied to the article 500. As with FIG. 1, a UV light 36 is then used to harden the medium 24.

FIG. 10 is a side elevation view of a third embodiment of the system for making phase change material products 32, generally designated as 220. As before, pieces of phase change material 22 are combined with a medium 24 in a vessel 28. The resulting mixture 26 is transferred to tool 30 which in this instance is a mold into which mixture 26 may be poured. The mold may be that of any traditional casting process. In this instance the phase change material product 32 is the casting which is formed by the mold. As with FIGS. 1 and 9, a UV light 36 is then used to harden the medium 24.

FIG. 11 is an enlarged top plan view of a tool 30 which is an extrusion die. Mixture 26 is forced out through apertures in the extrusion die to form phase change material product 32 (such as the shown strands).

FIG. 12 is an enlarged perspective view of a mass of phase change material 40 being ground to form pieces of phase change material 22. In the shown embodiment a grinder 600 is used to form the pieces of phase change material 22. Mass of phase change material 40 is in the solid phase, and the pieces of phase change material 22 are formed from mass 40. It may be appreciated that mass of phase change material 40 could be the shown block, a lump, a chunk, a sheet, or other form.

FIG. 13 is an enlarged view of a compressible material 42 (such as foam) added to the mixture 26 of pieces of phase change material 22 and a medium 24. It is noted that after medium 24 is transformed to the solid state, the pieces of phase change material 22 are closely surrounded by the hardened medium 24. As such, a problem can occur when the pieces of phase change material 22 are heated above the transition temperature and melt (change to the liquid phase). During melting the phase change material pieces 22 will expand, and thereby induce stresses in the solid medium 24. If large enough, these stresses could cause cracking of the medium 24. Compressible material 42 mitigates this effect by absorbing expansion as it occurs. Another way of lessening stresses is to add a porous material to mixture 26 (refer to FIG. 14 and the associated discussion). Other methods of stress reduction include (1) using a medium 24 which is slightly flexible when in the solid state; (2) reducing the particle size of the pieces of phase change material 22 to reduce the expansion effect; and (3) heating the mixture 26 above the transition temperature during the transition of the medium 24 to the solid state. That is, heating the mixture 26 once the medium 24 has setup but has not yet been fully transformed to the solid state, thereby allowing for expansion of the pieces of phase change material 22 without causing stress.

FIG. 14 is an enlarged view of a porous material 44 added to the mixture 26 of pieces of phase change material 22 and the medium 24. Porous material 44 absorbs the phase change material as it expands and thereby reduces expansion-related stresses.

In the present disclosure, the verb "may" is used to designate optionality /

noncompulsoriness. In other words, something that "may" can, but need not. In the present disclosure, the verb "comprise" may be understood in the sense of including. Accordingly, the verb "comprise" does not exclude the presence of other elements / actions. In the present disclosure, relational terms such as "first," "second," "top," "bottom" and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

In the present disclosure, the term "any" may be understood as designating any number of the respective elements, i.e. as designating one, at least one, at least two, each or all of the respective elements. Similarly, the term "any" may be understood as designating any collection(s) of the respective elements, i.e. as designating one or more collections of the respective elements, a collection comprising one, at least one, at least two, each or all of the respective elements. The respective collections need not comprise the same number of elements.

In the present disclosure, expressions in parentheses may be understood as being optional.

As used in the present disclosure, quotation marks may emphasize that the expression in quotation marks may also be understood in a figurative sense. As used in the present disclosure, quotation marks may identify a particular expression under discussion.

While various embodiments of the present invention have been disclosed and described in detail herein, it will be apparent to those skilled in the art that various changes may be made to the configuration, operation and form of the invention without departing from the spirit and scope thereof. In particular, it is noted that the respective features of the invention, even those disclosed solely in combination with other features of the invention, may be combined in any configuration excepting those readily apparent to the person skilled in the art as nonsensical. Likewise, use of the singular and plural is solely for the sake of illustration and is not to be interpreted as limiting.

The embodiments disclosed hereinabove may be summarized as follows.

Embodiment 1 :

A method for processing phase change material including:

(a) providing pieces of phase change material 22 having a transition temperature, the pieces of phase change material 22 being in a solid phase;

(b) providing a medium 24 which is transformable from a liquid state to a solid state, the medium 24 being in the liquid state and at a temperature which is below the transition temperature of the pieces of phase change material 22;

(c) combining the pieces of phase change material 22 with the medium 24 to form a mixture 26;

(d) providing a tool 30;

(e) transferring the mixture 26 to the tool 30;

(f) using the tool 30 to form a phase change material product 32;

(g) transforming the medium 24 to the solid state; and,

during (c), (e), and (f) the pieces of phase change material 22 being in the solid phase.

Embodiment 2:

The method of Embodiment 1, further including:

in (a), the providing of pieces of phase change material 22 including providing a mass 40 of phase change material which is in the solid phase; and, creating the pieces of phase change material 22 from the mass of phase change material 40.

Embodiment 3 :

The method of Embodiment 1 or Embodiment 2, wherein:

in (f), the phase change material product 32 is a sheet; and,

in (d), the tool 30 includes a roller which is configured to roll the mixture 24 into the sheet.

Embodiment 4:

The method of Embodiment 1 or Embodiment 2, further comprising:

in (f), the phase change material product 32 being a coating;

providing an article 500; and,

in (d), the tool 30 including a sprayer which is configured to spray the mixture 24 onto the article 500 to form the coating.

Embodiment 5:

The method of any one of Embodiments 1 to 4, further comprising:

providing a support surface 34;

prior to (f), depositing a layer of medium 24 upon the support surface 34 and transforming the layer of medium 24 to the solid state;

in (f), the phase change material product 32 being deposited on the layer of medium 24; and, after (g), depositing a second layer of the medium 24 upon the phase change material product 32 and transforming the second layer of medium 24 to the solid state.

Embodiment 6:

The method of Embodiment 1 or Embodiment 2, wherein:

in (f), the phase change material product 32 is a casting; and,

in (d), the tool 30 includes a mold into which the mixture 24 is pourable.

Embodiment 7:

The method of Embodiment 6, further comprising:

providing a sealer 38; and, prior to (g), using the sealer 38 to seal the phase change material product 32.

Embodiment 8:

The method of Embodiment 1 or Embodiment 2, wherein:

in (d), the tool 30 includes an extrusion die.

Embodiment 9:

The method of any one of Embodiments 1 to 8, further comprising:

during (c), adding a compressible material 42 to the mixture.

Embodiment 10:

The method of any one of Embodiments 1 to 9, further comprising:

during (c), adding a porous material 44 to the mixture.

Embodiment 11 :

The method of any one of Embodiments 1 to 10, further comprising:

during (g), said pieces of phase change material 22 being in said solid phase.

Embodiment 12:

The method of any one of Embodiments 1 to 11, further comprising:

during (g), raising a temperature of said mixture 26 above said transition temperature.

As applicable the order of performance of the above cited method steps may be changed.

Embodiment 13:

A manufacturing system, comprising:

pieces of phase change material 22 having a transition temperature, the pieces of phase change material being in a solid phase;

a medium 24 which is transformable from a liquid state to a solid state, medium 24 being in the liquid state and at a temperature which is below the transition temperature of the pieces of phase change material, medium 24 configured to combine with pieces of phase change material 22 to form a mixture 26; and,

a tool 30 which is configured to receive mixture 24 and form a phase change material product 32.

Embodiment 14:

The system of Embodiment 13, further including:

phase change material product 32 being a sheet; and,

tool 30 including a roller which is configured to roll mixture 26 into the sheet.

Embodiment 15:

The system of Embodiment 13, further including:

an article 500;

phase change material product 32 being a coating; and,

tool 30 including a sprayer which is configured to spray mixture 26 onto article 500 to form the coating.

Embodiment 16:

The system of Embodiment 13, further including:

tool 30 including a mold into which mixture 26 is pourable.

Embodiment 17:

The system of any one of Embodiments 13 to 16, further including:

a mass of phase change material 40 which is in the solid phase; and,

pieces of phase change material 22 formed from mass of phase change material 40.

Embodiment 18:

The system of any one of Embodiments 13 to 17, further including:

phase change material product 32 including a layer of mixture 26 sandwiched between first and second layers of medium 24. Embodiment 19:

The system of any one of Embodiments 13 to 18, further including: a sealer which is configured to seal phase change material product 32. Embodiment 20:

The system of Embodiment 13, further including:

tool 30 including an extrusion die.

Embodiment 21 :

The system of any one of Embodiments 13 to 20, further including: mixture 26 including a compressible material 42.

Embodiment 22:

The system of any one of Embodiments 13 to 21, further including: mixture 26 including a porous material 44.