WO2012128611A1

WO2012128611A1 - Latent heat storage heat exchanger

Info

Publication number: WO2012128611A1
Application number: PCT/NL2011/050191
Authority: WO
Inventors: Antonius Hubertus Henricus Schmitz; Marcel Reijer GOUW
Original assignee: Autarkis B.V.
Priority date: 2011-03-18
Filing date: 2011-03-18
Publication date: 2012-09-27

Abstract

The invention relates to a latent heat storage heat exchanger(1) for use in a climate control system. The latent heat storage heat exchanger comprises a plurality of plate shaped elements (6), wherein the plate shaped elements are parallel positioned at a predetermined distance with respect to each other to form a fluid channel (7) between adjacent plate shaped elements and each element comprises a cavity filled with a phase change material. The latent heat storage heat exchanger comprises a coupling structure (8) configured to coupled the cavities of the plurality of plate shaped elements (6) to form one coupled cavity filled with phase change material.

Description

Latent heat storage heat exchanger

TECHNICAL FIELD OF THE INVENTION

The invention relates to a latent heat storage heat exchanger for use in a climate control system. The invention relates to the use of such a climate control system for controlling the temperature in a building. Further, the invention relates to a method of manufacturing a latent heat storage heat exchanger, the use of a latent heat storage heat exchanger in a climate control system. Furthermore, the invention relates to a climate control system. The invention further relates to an insert for a latent heat storage heat exchanger, and to a latent heat storage heat exchanger provided with such an insert.

BACKGROUND OF THE INVENTION

Climate control systems for buildings are generally known. Some of said climate control systems use a phase change material to provide a latent heat storage.

WO2003102484 A2 discloses a climate control unit located in the vicinity of the ceiling. The climate control unit comprises plate shaped latent heat accumulator bodies. The plate shaped bodies are parallel positioned at a predetermined distance with respect to each other to form an air channel between adjacent plate shaped bodies. The plate shaped bodies comprise a cavity filled with a phase change material. A phase change material (PCM) is a substance with a high latent heat of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid and vice versa. Bodies filled with PCMs are classified as latent heat storage (LHS) units.

The plate shaped bodies have to be manufactured separately. Subsequently, the plate shaped bodies are positioned parallel in the climate control unit. The plate shaped bodies together form a latent heat storage heat exchanger. Such a latent heat storage heat exchanger comprises a plurality of plate shaped elements. The plate shaped elements are parallel positioned at a predetermined distance with respect to each other to form an air channel between adjacent plate shaped elements. Each element comprises a cavity filled with a phase change material. The number of individual plate shaped elements mainly defines the costs of a climate control unit. Consequently, relative large plate shaped elements are used in climate control units instead of smaller ones. SUMMARY OF THE INVENTION

The object of the invention is to provide an improved latent heat storage heat exchanger for use in a climate control system which allows to realize at least one of: reduction of manufacturing costs of climate control unit, increased latent heat storage capacity in Wh/kg or Wh/L, increased heat transfer characteristics compared with the known embodiment of a climate control unit provided with parallel and horizontal positioned plate shaped latent heat storage bodies.

According to the invention, this object is achieved by a system having the features of Claim 1. Advantageous embodiments and further ways of carrying out the invention may be attained by the measure mentioned in the dependent claims.

According to the invention, the latent heat storage heat exchanger comprises a coupling structure configured to coupled the cavities of the plurality of plate shaped elements to form one coupled cavity filled with phase change material.

The invention is based on the recognition that the manufacturing costs of a climate control unit provided with a latent heat storage heat exchanger comprising a plurality of plate shaped elements comprising a PCM-material is linear to the number of elements. Each of the known plate shaped elements is obtained by the following process steps: manufacturing the body; filling the body with a PCM-material via an opening in the body; sealing the body. Subsequently, each element has to be positioned in the climate control unit. By manufacturing a body which comprises the coupling structure according to the invention, one latent heat storage heat exchanger is obtained having the features of a plurality of plate shaped elements when positioned in a climate control unit, but which could be obtained be much less processing steps, namely manufacturing the body with the coupling structure; filling the body, i.e. all plate shaped elements, in one run, and sealing the body. Subsequently only one body instead of a plurality of plate shaped elements has to be positioned in the climate control unit. In this way, the manufacturing costs of a climate control unit is reduced. Furthermore, the coupling structure enables us to provide a latent heat storage heat exchanger provided with a multitude of smaller plate shaped elements without increasing the amount of processing steps and thus the manufacturing costs of a latent heat storage heat exchanger. Further, the coupling structure functions as a spacer to position the plate shaped elements parallel and at a predetermined distance to each other. In an embodiment of the invention, the coupling structure divides the fluid channel between adjacent plate shaped elements in two channel parts. In an advantageous embodiment, the coupling structure divides the fluid channel between adjacent plate shaped elements symmetrically in two equal channel parts. These features provide a robust structure, wherein the coupling structure extends along the complete length of the fluid channel between two adjacent plate shaped elements.

In an embodiment of the invention, the coupling structure forms a plate shaped cavity which is perpendicular to the plurality of plate shaped elements. This feature provides a structure which makes it easy to fill each of the plate shaped elements of the latent heat storage heat exchanger with a PCM-material.

In an embodiment of the invention, the coupling structure has a length axis which is larger than a length axis of the plate shaped elements. This feature provides a latent heat storage heat exchanger with relative small plate shaped elements. This allows us the provide a latent heat storage heat exchanger with improved characteristics without increasing the flow rate through the latent heat storage heat exchanger. An improved characteristic could be the latent heat storage capacity, the total surface of the plate shaped elements along the air channels, the air resistance, as the air channels be shorter, or any other combination of improved characteristics.

In an embodiment of the invention, the latent heat storage heat exchanger comprises a housing of one material to form the one coupled cavity. The housing comprises a bin part and a cover part, wherein the bin part forms essentially the one coupled cavity. This feature enables one to design a housing that could be manufactured by means of an injection moulding process. The housing could be made from HDPE (High Density Poly Ethylene).

In an embodiment of the invention, the cover part comprises at least one opening for filling the one coupled cavity with the PCM-material. In an embodiment of the invention, the openings are configured for receiving a sealing member. In an advantageous embodiment, the opening and the sealing member are coupled by means of a screwed connection. In another embodiment, the opening and sealing members are coupled by means of gluing or welding.

In a further embodiment, the bin part and the cover part are coupled by means of one continuous circular weld. After the bin part and the cover part are positioned on each other, a heating element having a shape complementary to the exterior shape of the body where the bin part and cover part touches is positioned along the exterior where the cover part and bin part touches. The touching ends of the bin part and cover part will fuse together to form the one continuous circular weld.

It is a further aspect of the invention to provide an improved method of manufacturing a latent heat storage heat exchanger. The method comprises the steps:

- manufacturing a bin part for a latent heat storage unit according to the invention;

- manufacturing a cover part for a latent heat storage heat exchanger according to the invention;

- welding the bin part and the cover part together to form a body with one coupled cavity according to the invention; and,

- filling the one coupled cavity with a PCM-material.

It is a further aspect of the invention to use a latent heat storage heat exchanger in a climate control system. Furthermore, an aspect of the invention is reduce the manufacturing costs of a climate control system by including at least one latent heat storage heat exchanger according to the invention in the system.

The invention further pertains to a latent heat storage heat exchanger for holding PCM-material having in at least two of its dimensions and a inside wall spacing of not more than 1 cm and comprising an insert.

It will be clear that the various aspects mentioned in this patent application may be combined and may each be considered separately for a divisional patent application. Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawing which illustrate, by way of example, various features of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES

These and other aspects, properties and advantages of the invention will be explained hereinafter based on the following description with reference to the drawings, wherein like reference numerals denote like or comparable parts, and illustrating in:

FIG. 1 a perspective view of a bin part and cover part of a latent heat storage heat exchanger according to an illustrative embodiment of the invention;

FIG. 2 top view of the embodiment shown in FIG. 1;

FIG. 3 a sectional view of the embodiment along the line III - III in FIG. 2; FIG. 4 an enlarged view from FIG. 3 showing the coupling part between the bin part and the cover part before the fusing process;

FIG. 5 a sectional view of the embodiment along line V -V in FIG. 2;

FIG. 6 in more detail an embodiment of an opening structure and sealing member;

FIG. 7 a perspective view of an insert for a bin part, in particular the heat exchanger of figure 1;

FIG. 8 a side view of figure 7;

FIG. 9 a top view of figure 7;

FIG. 10 a detail of figure 8, and

FIG. 11 a further detail of figure 7.

DESCRIPTION OF EMBODIMENTS FIG. 1 illustrates a perspective view of a bin part 4 and cover part 2 of a latent heat storage heat exchanger 1 according to an illustrative embodiment of the invention. FIG. 1 shows the cover part 2 positioned above and at distance from the bin part 4. The bin part 4 and cover part 2 could be made by an injection moulding process. The material could be any suitable injection moulding material. High Density Poly Ethylene HDPE has been found a very suitable material for both the bin part and the cover part. The bin part 4 and the cover part form together a housing with one coupled cavity. The cavity could be filled with a phase change material (PCM). Therefore, the cover part 2 comprises two openings 9 positioned at opposite ends of the cover part 2. One opening is used to supply the PCM in the cavity and the other opening is used to release air when filling the cavity with PCM. After filling the housing 2,4, formed by bin part 4 and cover part 2, the openings 9 are closed with a sealing number 10.

The housing formed by the bin part 4 and the cover part 2, comprises a plurality of plate shaped elements 6. Each plate shaped element 6 comprises a cavity for receiving PCM. The plate shaped elements 6 are positioned parallel to each other. A predefined spacing 7 is provided between the plate shaped elements 6 to form a fluid channel 7. It should be noted that the invention is not limited to plate shaped elements with a flat surface. For example, the surface could be enlarged, for instance by making the surface curved or corrugated. The plate shaped elements 6 are coupled together to form one housing by means of a coupling structure 8. In the embodiment shown in FIG. 1, in the middle of two adjacent plate shaped elements 6, a passage between the cavities of two adjacent plate shaped element 6 is provided. The walls of the passage form a rigid coupling structure to keep the two adjacent plate shaped elements parallel to each other and at a predefined distance to form a fluid channel between the plate shaped elements. The passages together form the coupling structure 8. The coupling structure 8 divides the fluid channel between adjacent plate shaped elements in two channel parts. In the embodiment, the passage extends from the bottom of the bin part 4 to the cover part 2. Consequently, in the embodiment the height of the passage is essentially equal to the height of the cavity of the plate shaped elements. The height is defined as the distance between the bottom side and top side of the housing. It should be noted that it is not essential to have a passage between two adjacent plate shaped elements which extends from the bottom to the top side. It might be possible to have two passages, one at the bottom side between two plate shaped elements and one at the top side between two plate shaped elements. In such an

embodiment, the passage at the bottom side is used to supply the PCM in all the cavities of the plate shaped elements and the passages at the top side allows to release the air from a plate shaped element when filling the cavity. In this way, each cavity of a plate shaped element could be filled completely with a PCM.

The housing of the latent heat storage heat exchanger 1 could also be described in the following way. A plate shaped coupling structure 8 provided with a plurality of plate shaped elements 6 or ribs at both sides of the coupling structure 8. The plate shaped elements 6 extending essentially perpendicular from the plate shaped coupling structure8. The plate shaped elements 7 are positioned parallel to each other at a predetermined distance. The space between the plate shaped elements 6 forming a fluid channel 7 configured for passing a flow of fluid along the surface of the plate shaped elements 6 to exchange heat between the PCM in the latent heat storage heat exchanger and the fluid passing along the fluid channel 7. A fluid could be a gas or a liquid. In an air ventilation system it is likely that the fluid is a cooled or heated air flow.

A cross section of two adjacent plate shaped elements 6 and the coupling structure 8 between said elements form the shape of a letter H. The two adjacent plate shaped elements 6 correspond to the legs of the letter H and the coupling structure corresponds to the cross of the letter H. The space between the legs of the letter H corresponds to the fluid channel. A latent heat storage as a whole comprises a plurality of H-shaped parts. FIG. 2 illustrates top view of the embodiment shown in FIG. 1 and shows the plurality of H-shaped parts. Similarly, a cross section of the cavity formed by the housing of a combination of two adjacent plate shaped elements and the coupling structure between said adjacent elements form the shaped of a letter H.

FIG. 2 further shows two filling openings 10 for filling the cavity of the housing of the latent heat storage heat exchanger with a PCM. The coupling structure 8 comprises a length axis, which is indicated by the line V-V. The openings 10 are positioned preferably near both ends of the coupling structure along the length axis.

FIG. 3 illustrates a sectional view of the embodiment along the line III - III in FIG. 2. Reference 8a indicates the cavity formed by the coupling structure 8.

Assume, the latent heat storage heat exchanger has an outer profile with the geometry of a rectangular cube. The cube having a length L, a height H and a depth D, wherein L > H > D. To obtain an optimal ratio with respect to contact surface between PCM and fluid channel, cross section of the fluid channel and amount of PCM-material, the coupling structure 8 is parallel to the side having a length L and a width H of the cube. The plurality of plate shaped elements 6 are parallel to the side having a length H and a width D of the cube. Compared with known latent heat storage heat exchangers with a predefined size of for example L = 570mm, H = 160mm and D = 148mm and plate shaped elements parallel to the side having a length L and a width D a significant increase of contact surface and volume of PCM is possible. Furthermore, as the length of the air channel through the latent heat storage heat exchanger decreases and the cross section of the air channel through the unit increases, the air resistance of the latent heat storage heat exchanger when applied in a ventilation system decreases.

In an embodiment, the plate shaped elements have a thickness which is larger than two time the width of the air channel between two adjacent plate shaped elements, for example a thickness of 11mm and a width of 4mm. It should be noted that the dimensions of the plate shaped elements and the distance between the plate shaped elements depend on the application of the latent heat storage heat exchanger and relate to parameters such as flow, desired latent heat storage capacity, daily cycles, cooling/heating capacity, medium, etc.

FIG. 4 illustrates an enlarged view from FIG. 3 showing the coupling part between the bin part 4 and the cover part 2 before the fusing process. The bin part comprises a rim 4a which can be positioned in a groove between a first rim 2a and a second rim 2b on the edge of the cover part 2. By heating the material of the first rim 2a and rim 4a, the material of the first rim 2a and the rim 4a will fuse and form one continuous circular weld. This could be done with a heating device with a heating profile which is congruent to the outline of the housing at the location of the coupling part. It might be clear that the heating profile comprises a plurality of parts having the shape of the letter H.

FIG. 5 illustrates a sectional view of the embodiment along line V -V in FIG. 2 and FIG. 6 illustrates in more detail an embodiment of an opening structure 9 and sealing member 10. The opening structure 9 comprises a thread 9a at the inner surface of the opening 9. The sealing member 10 comprises a threaded outer surface 10 a for forming a screwed connection with the opening structure 9. It might be clear that other sealing constructions are possible. In an alternative embodiment the material of the opening structure and sealing member are fused together. In another embodiment, glue is used to secure the sealing member 10 in the opening 9.

The present invention enables one to manufacture a latent heat storage heat exchanger comprising a plurality of parallel positioned plate shaped elements by means of the following process steps:

1) Produce a bin part with feature described above by means of an injection moulding process from a material such as HDPE;

2) Produce a cover part with features described above by means of an injection moulding process from the similar material as the bin part;

3) Position the cover part on the bin part;

4) Position a heating device along the contour defined by the outer profile of the surface where the cover part is positioned on the bin part;

5) Heat the material of the bin part and the cover part near the

touching location;

6) Fuse the bin part and the cover part in one go to obtain one

continuous circular weld (corresponds to the profile of the upper edge of the bin part and the lower part of the cover part) to obtain a housing with one coupled cavity including the cavity formed by the coupling structure and the cavities of the plurality of plate shaped elements;

7) Fill in one go the one coupled cavity with a PCM though one or more filling openings; and 8) Seal the one or more filling openings with a sealing member.

The method according to the invention enables one to manufacture a plurality of parallel positioned plate shaped elements for use in a climate control system by performing each of the steps 1 - 8 only once. This has been made possible by providing a coupling structure between the plate shaped elements and which structure comprises a cavity which provides a fluid passage between cavities of the plate shaped elements.

In figure 7, an embodiment of another aspect of the invention is shown, in an embodiment specifically designed for the heat exchanger of figure 1. It was found that when filling the storage unit of figure 1 with PCM material, for instance PCM material based upon CaCl₂-6H₂0, that the crystal material tends to precipitate under the influence of gravity. When this happens, the PCM material largely loses its ability to store heat and it effects the under cooling. It was found that when inserting the insert of figure 7, the precipitation can be prevented. In fact, the particular insert even allows the heat exchanger of figure 1 to be used in any spatial orientation.

The insert in fact divides the larger volume of the storage unit into smaller sub spaces. In fact, in this embodiment it divides a larges space into sub spaces with each dimension smaller than 2.5 cm.

In the embodiment or figure 7, the insert has interconnected strips of material having a width to fit between two opposite walls of the storage unit. The strips are provided with openings to allow the storage unit to be filled with PCM material after the insert 20 is inserted into the storage unit 1. With holes having a diameter smaller than 2 mm, it prevents the crystal material to precipitate. In fact, it was surprisingly found that the material tends to stick to the material of the insert, even if it is made, for instance via an injection moulding process, from a plastic material. In examples, the insert is made of PE (polyethylene). The insert can be made of another, similar material like PP

(polypropylene).

In this embodiment, the insert comprises strips that have a width corresponding to the width of the storage unit. Thus, it divides the storage unit in compartments. In this embodimen, strips 21 have a series of crosswise attaches strip parts 21 that are arranged to fit together to functionally form single cross strips 22, Thus, the insert can be formed as series af sub-inserts that are connected via transvers strips 23 . In this embodiment for the heat exchanger of figure 1, these strips 23 are provided to close off coupling structure 8. The cross strips 22 are usually perperdicular with respect to the strips 21. The strips 21 in one level are connected via bridging parts 26. Thes bridging parts can be provided with slots for the transverse strips 23. In yet another embodiment, the entire insert can be formed as one single injection moulding part.

In another embodiment, a similar insert can also be used in order to divide another shaped heat exchanger into sub compartments. Thus, the storage unit can be used in any desired orientation.

In figure 10, a detail of the insert is shown. A strip or fin has holes in order to allow the PCM material to fill the spaced defined by the strips and the further walls of a storage unit. In figure 11, yet another detail is shown, showing the holes in the strips 22, 21.

In an embodiment, the latent heat storage heat exchange unit has another shape than the shown block shape. For instance, in some applications a trapeziod shape is preferren, in order to have heat transfer properties tailored to the need. In another application, when tubes are used, a cylinder shape is perferred. In such a shape, the plates are disks and are essentially parallel with respect to one another. It may even be possible to position the plates of the latent heat exchanger a little off parallel, in order to modify the flow chanel.

The measures described hereinbefore for embodying the invention can obviously be carried out separately or in parallel or in a different combination or if appropriate be supplemented with further measures; it will in this case be desirable for the implementation to depend on the field of application of the device. The invention is not limited to the illustrated embodiments. Changes can be made without departing from the idea of the invention.

Claims

CLAIMS:

1. A latent heat storage heat exchanger (1) for use in a climate control system, the latent heat storage heat exchanger comprises a plurality of plate shaped elements (6), wherein the plate shaped elements are parallel positioned at a predetermined distance with respect to each other to form a fluid channel (7) between adjacent plate shaped elements and each element comprises a cavity filled with a phase change material,

characterized in that, the latent heat storage heat exchanger comprises a coupling structure (8) configured to coupled the cavities of the plurality of plate shaped elements (6) to form one coupled cavity filled with phase change material.

2. Latent heat storage heat exchanger according to claim 1, characterized in that, the coupling structure (8) divides the fluid channel between adjacent plate shaped elements in two channel parts.

3. Latent heat storage heat exchanger according to claim 2, characterized in that, the coupling structure (8) divides the fluid channel between adjacent plate shaped elements symmetrically in two equal channel parts.

4. Latent het storage heat exchanger according to any of the claims 1 - 3, characterized in that, the coupling structure forms a plate shaped cavity which is perpendicular to the plurality of plate shaped elements.

5. Latent heat storage heat exchanger according to any of the claims 1 - 4, characterized in that, the coupling structure has a length axis which is larger than a length axis of the plate shaped elements.

6. Latent heat storage heat exchanger according to any of the claims 1 -5, characterized in that, the latent heat storage heat exchanger comprises a housing of one material to form the one coupled cavity.

7. Latent heat storage heat exchanger according to claim 6, characterized in that, the housing comprises a bin part and a cover part, wherein the bin part forms essentially the one coupled cavity.

8. Latent heat storage heat exchanger according to claim 7, wherein the bin part and the cover part are injection moulded parts.

9. Latent heat storage heat exchanger according to claim 7 or 8, wherein the cover part comprises at least one opening (9) for filling the one coupled cavity with the PCM material.

10. Latent heat storage heat exchanger according to claim 9, wherein the openings are configured for receiving a sealing member (10) .

11. Latent heat storage heat exchanger according to claim 10, wherein the opening and sealing member are coupled by means of a screwed connection.

12. Latent heat storage heat exchanger according to any of the claims 6 - 8, wherein the housing is made from HDPE.

13. Latent heat storage heat exchanger according to any of the claims 7 - 12, wherein the bin part and the cover part are coupled by means of one continuous circular weld.

14. A latent heat storage heat exchanger for holding phase change material

(PCM), in particular a latent heat storage heat exchanger according to any one of the preceding claims, said latent heat storage heat exchanger comprising a plurality of interconnected walls defining a PCM-holding space, said latent heat storage heat exchanger comprising an insert having crossed ribs for dividing said latent heat storage heat exchanger into subspaces that are in fluid connection.

15. The latent heat storage heat exchanger of claim 14, wherein said insert divides said latent heat storage heat exchanger into subspaces which have walls separated less than 3 cm, in particular less than 2.5 cm.

16. The latent heat storage heat exchanger of any one of the claims 14 or 15, wherein said insert has fluid connections fluidly connecting a neighbouring subspace.

17. The latent heat storage heat exchanger of any one of the claims 14-16, wherein the ribs of said insert comprises strips having a width to fit between two opposite walls of the storage unit, in particular sealingly fit between the opposite walls.

18. The latent heat storage heat exchanger of any one of the claims 14-17, wherein said ribs comprises strips that are crosswise interconnected to form subspaces.

19. The latent heat storage heat exchanger of any one of the claims 14-18, wherein said opposite walls of said heat exchanger are less than 20 mm apart, in an embodiment less than 10 mm apart, in a further or additional embodiment said walls are essentially parallel, and in a further or additional embodiment said ribs comprise strips having a width matching the space between the opposite walls, in particular sealingly matching, and in a further or additional embodiment said strips connected to form rectangles having sides less than 3 cm apart, in an embodiment less than 1 cm apart.

20. The latent heat storage heat exchanger of any one of the claims 14-19, wherein said insert is made of plastic, in particular made of polyethylene, in an embodiment injection moulded, in an embodiment thereof injection moulded as one single part.

21. Method of manufacturing a latent heat storage heat exchanger, the method comprising the steps:

- providing a first part comprising the features of a bin part according to any of the claims 7 - 12;

- providing a second part comprising the features of a cover part according to any of the claims 7 - 12; - welding the first part and the second part together to form the one coupled cavity according to claim 1 ;

- filling the one coupled cavity with a PCM-material.

22. Method according to claim 21, furthermore comprising inserting the insert of claims 14-20 into said bin part before providing said cover part onto said bin part.

23. Use of a latent heat storage heat exchanger having the technical features of any of the claims 1 - 13 in a climate control system.

24. Climate control system comprising at least one latent heat storage heat exchanger according to any of the claims 1 - 13.