WO1999053258A1

WO1999053258A1 - Heat accumulator, especially a pcm device

Info

Publication number: WO1999053258A1
Application number: PCT/EP1999/002012
Authority: WO
Inventors: Stephan HÖRZ; Gregory G. Hughes
Original assignee: Modine Manufacturing Company
Priority date: 1998-04-08
Filing date: 1999-03-24
Publication date: 1999-10-21
Also published as: DE19815777A1; CN1256751A; CA2286567A1; JP2002504219A; EP0988499A1; KR20010013477A

Abstract

The invention relates to a heat accumulator, especially a PCM device, provided with thermal insulation (4), at least one inlet (2) and one outlet (3), and collector areas (12) for the heat carrier medium that are fluidically connected to the storage core which is surrounded by a housing, whereby flow paths (tubes) (5) are arranged therein and the inventive device is provided with areas in between the flow paths where phase change material can be found. Such heat accumulators can be more easily adapted to small, angular installation areas while at the same time maintaining a storage capacity, high load and unload dynamic characteristics and can be produced inexpensively when the flow paths (5) are made of oval or flat tubes which are conducted through the storage core in a spiral or undulated form and the areas (9) for the phase change material are arranged between the individual flow paths (5) and the undulated shapes (10) or windings (18) of the individual flow paths (5) and are at least for the most part taken up by heat conducting elements (8) which are metallically connected to the flow paths (5). The heat conducting elements (8) are configured as undulated thin strips of sheet metal whose width is greater than the large diameter of the tubes that form the flow paths (5).

Description

Heat storage, in particular latent heat storage

The invention relates to a heat store, in particular a latent heat store, with thermal insulation, with at least one inlet and one outlet and collecting spaces for the heat transfer medium, which are fluidly connected to the storage core surrounded by a housing, in which flow paths (pipes) are arranged and which has spaces between the flow paths in which there is a phase change material.

Such a heat store is known from a whole series of documents, for example also from WO 89 / 09375. The known heat store has inlet and outlet plenum spaces into which the flow paths (individual flat tubes) open. The collection rooms mentioned take up a considerable space, as can be seen in particular from FIG. 5 of the document mentioned.

The problem, which has already been raised in many different ways, is that the available installation space for heat storage devices is becoming ever smaller, but at the same time the demands for constant or even increasing heat capacity of the heat storage devices, with a view to the necessary energy reductions through improved storage of heat loss, are being emphasized more and more Industry faces growing challenges. The heat accumulator known from DE 195 30 378 C1, which is, however, not a latent heat accumulator but a hot water accumulator, makes a contribution to solving this problem, based on the installation space in motor vehicles. In this document it is shown that the rooms not only become smaller in terms of their volume, but are also more and more branched, so that one wants to fully exploit the installation space.

From these restrictive points of view, the latent heat accumulator known from the first-mentioned document can no longer be regarded as particularly suitable because of its collecting spaces which take up space, but also for manufacturing reasons. For example, this design has many solder joints that always pose a risk, many individual parts that have a negative impact on the manufacturing process, and a relationship between the flow spaces and the spaces in which the phase change material is accommodated, which needs to be improved.

Heat exchangers have also been proposed (DE 29 42 147 A1) which have meandering flow paths. Although this heat exchanger also has storage properties, it is unsuitable because it is complex to manufacture and disadvantageous in terms of performance, since the phase change material is housed in envelopes. The flow paths each consist of two flat plates which are joined together and between which the flow paths are formed by means of inflation. The plates between the flow paths reduce the space for the phase change material and therefore lead to a reduced storage capacity. The latent memory from DE 32 27 322 A1 consists of modules which are anode one above the other and surrounded by insulation. Spiral hollow bodies are arranged within the individual modules, which are enclosed by a housing, and communicate in the center. Spaces are provided within the housing in which the latent storage agent can expand during melting. The latent storage described is intended for storage tanks to be set up in buildings, for which it is not important to provide storage with high loading and unloading dynamics in the smallest of spaces, but rather the most complete possible melting of the latent storage means should be achieved, for which purpose a complex and complicated flow through the hollow body and regulation of the heat transfer medium is provided.

The object of the invention is to better adapt the heat store described in the preamble to smaller and angled installation spaces while maintaining a high storage capacity, high loading and unloading dynamics and favorable manufacturing costs. The solution according to the invention results from the patent claims.

It provides that the flow paths are wavy or spiral through the storage core and the wave height and / or wavelength or the geometry of the turns can be irregular within a flow path and / or between several flow paths. The flow paths are preferably flat tubes, e.g. Can have internal inserts. However, it is particularly advantageous if the flat tubes are so-called multi-chamber tubes, as used for example in condensers or evaporators. Such tubes can be easily shaped without bending in the bends and provide the necessary turbulence of the heat transfer medium and a larger heat exchange surface within the flat tubes.

The geometry of the waves or the windings of the flow paths can be irregular. Where the wave height of the flow paths fluctuates, that is, becomes smaller or larger, or where the geometry of the windings is irregular, the housing of the storage core and of the entire heat accumulator is also drawn in or expanded accordingly. In this way, the heat accumulator can be adapted very cheaply to angled installation spaces, without this causing significant manufacturing costs, because the manufacturing technology for such undulating or spiral flow paths is available from the manufacturers of the heat exchange technology and the irregular wave height is simply a question of machine setting. In comparison with the prior art, in which individual flat tubes are provided, these would have to be cut to different lengths and inserted and connected into the openings of the tube sheets under complicated conditions. All of this is more complex overall. The design according to the invention only requires small spaces, which can be referred to as collecting spaces, wherever a flow path enters the storage core and where it exits. The space between the waves or between the windings of the flow paths and around the flow paths is used as space for accommodating the phase change material, whereby the ratio of the room sizes has been changed in favor of a larger space for the phase change material. This makes it possible to expect at least consistently high storage capacities, even in the case of smaller sizes of the heat store, which corresponds to the requirements in the best possible way.

The space mentioned for the phase change material is almost completely covered with corrugated sheets. Such lamellae can also be arranged in the region of the bends of the flow paths. Because the phase change material is a poor heat conductor and therefore tends not to melt completely and therefore does not always reach its maximum heat storage capacity, the fullest possible occupancy of the rooms with the corrugated sheets is an essential contribution to increasing the storage capacity. Furthermore, the slats make a not negligible contribution to the stability of the heat accumulator.

A major advantage of the inventive heat store is that the temperature changes associated with tensile and compressive loads on the pipes can be withstood much better because the undulating or spiral flow paths are relatively long and therefore flexible and because they are only clamped on one side while they are firmly clamped on opposite sides in tube sheets in the prior art. The load on the metallic connections of the flow paths with the housing of the storage core is substantially lower than in the prior art, so that the risk of breakage has been significantly reduced. It can therefore be assumed that the heat accumulator according to the invention has better fatigue strength, combined with fewer failures due to broken solder connections. Further possibly important features and advantageous effects result from the following description of exemplary embodiments which are illustrated in the accompanying drawings. The invention is in no way limited to these exemplary embodiments, since they only serve for better understanding and as an aid to interpretation. The individual figures show: FIG. 1 Overall spatial view of a latent heat storage in principle, open at the front and top;

Fig. 2 principle of a trapezoidal heat accumulator in cross section;

Fig. 3 variant of Fig.2;

Fig. 4 heat storage with a constriction;

Fig. 5 View A of Fig. 4; Fig. 6 heat storage with internal collection rooms; Fig. 7 and

8 shows an exemplary basic illustration of a heat accumulator with different flow paths and shapes; Fig. 9 section B in Fig. 7; Fig. 10 spiral flow path; 11 heat accumulator with such flow paths;

The latent heat store 1 is intended for installation in the engine compartment of a motor vehicle. In these exemplary embodiments, the cooling water of the engine is the heat transfer medium, which is guided by a cooling water pump in the circuit (not shown), in which the latent heat accumulator 1 is integrated with its inlet 2 and with its outlet 3. The insulation 4 can be a highly effective vacuum insulation which makes it possible to keep the melted and heat-absorbing phase change material in this storage state for almost 50 hours, even under winter conditions. When the engine is started, the cooling water pump conveys the cold cooling water through the flow paths 5, within the storage core 6 of the latent heat store 1. The cooling water then exchanges heat with the phase change material, which begins to crystallize and transfers its storage heat to the cooling water. The rapidly heated cooling water shortens the engine's start-up phase and thus fuel consumption and can also be used to heat the passenger compartment.

In the advanced operating state, the hot cooling water releases its heat to the phase change material, causing it to melt again and thereby store heat. This interplay is repeated continuously, so that the entire heat store, but in particular the flow paths 5, which are formed here from flat multi-chamber tubes 7 and whose connections are exposed to enormous stresses. However, because the flow paths 5 are relatively long and flexible and the corrugated sheets 8 are not very rigid, the thermal stresses are largely compensated for. Breaks in soldered or welded connections are normally excluded. The corrugated sheets 8 are arranged in the spaces 9 which are provided for the phase change material. These spaces 9 are located between the shafts 10 of the flow paths 5 and also between the individual flow paths 5. The arrangement of the corrugated sheets 8 is described in more detail below.

Both the inlet 2 and the outlet 3 each merge into a thermosiphon-shaped tube, which are arranged within the insulation 4, whereby in the idle state a stratification of the cooling liquid is established within the tubes in such a way that the cooling water has a higher temperature due to its lower density , remains above or within the insulation and does not mix with the cooling water in the pipes outside the insulation 4, which is colder and has a higher density. The pipe end directed downward from the arc of the thermosiphon is the collecting space 12, into which, in the exemplary embodiment according to FIG. 1, the pipe ends of the four flow paths 5 open and are connected there, which need not be discussed in more detail here. Before the pipe ends open into the collecting spaces 12, they break through the housing 11 of the storage core 6.

2 and 3 are different in that they have a different arrangement of the corrugated sheets 8 and the collecting spaces 12. The heat accumulator from Fig. 2 shows in addition, the outer housing 14 of the heat accumulator 1 and the insulation space 4 formed between the outer housing 14 and the housing 11 of the storage core 6, in which some supports 13 made of non-heat-conducting material are arranged. The insulation space 4 is vacuum insulation and the supports 13 ensure that the inner housing 11 and the outer housing 14 do not touch in order to keep the insulation effect at a high level. The thickness of the insulation 4 is only a few millimeters and thereby contributes to minimizing the outer dimension of the latent heat store 1. In Fig. 3 longer corrugated sheets 8 have been used to minimize the number of components, which are laid around the bends of the flow paths 5. In contrast, it can be seen in Fig. 2 that 5 individual corrugated sheets 8 are arranged between each shaft 10 of the flow path. To further minimize the size of the heat accumulator 1, the collecting spaces 12, in FIG. 3, are only half-shell-shaped. The subsequent thermosiphon-like inlet 2 and outlet 3 were not drawn here or in the following figures. 4 and 6 show an approximately trapezoidal cross section through a heat accumulator 1, FIG. 4 having a constriction 15, which was provided because the installation space requires this. The waves 10 of the flow paths 5 are adapted to this irregular shape by having a shape adapted to the constriction 15. As a result, such a shape - referred to as irregular - of the heat store 1 or of the storage core 6 can be used quite simply and as completely as possible with flow paths 5 and spaces 9 for the phase change material. An advantageous variant is shown in FIG. 6, which consists in the fact that the collecting spaces 12 have been arranged within the storage core 6. In this way, on the one hand, interiors of the storage core 6, which cannot be covered particularly cheaply with corrugated sheets 8, can be used as a collecting space 12, and on the other hand, the insulation space 4 (not shown here) can be further reduced. 5 is only in principle a view of the heat accumulator 1 according to the arrow A in FIG. 4. However, the collecting spaces 12 have been broken open so that the multi-chamber tubes 7 which open into the collecting spaces 12 can be seen. The multi-chamber tubes 7 form the undulating flow paths 5, between which the undulating sheets 8 are located. 5 shows that the corrugated sheets 8 have a greater width than the large diameter of the multi-chamber tubes 7. This results in a protrusion 16 of the corrugated sheets

8 via the multi-chamber pipes 7, or via the flow paths 5, which leads to the rooms

9 for the phase change material between the individual flow paths 5 are also covered with the corrugated sheets 8. The wave-shaped plates 8 are soldered to the flow paths 5 and the outer plates 8 also to the inner housing 11. In Fig. 5, above, the approach to the thermosiphon was drawn in as well as flow arrows, which should indicate that the cooling water comes from inlet 2 and flows out again via outlet 3.

7, 8 and 9 show in a special way the various possibilities with regard to the shape of heat accumulators 1 and the design of the shape adapted to the respective shape Flow paths 5, which are also arranged in a wave shape in this exemplary embodiment. 7 shows that the waves 10 of the individual flow paths 5 have very different wave heights in order to be adapted to the shape of the reservoir 1 with constrictions 15 and bulges 17. FIG. 9, which shows section B through FIG. 7, makes it clear that the design is variable in all three dimensions. Multi-chamber pipes 7 have also been used here to form the flow paths 5. The flow paths 5 are arranged approximately parallel to one another. The collection rooms 12 were not drawn in these representations. The basic representations in FIGS. 10 and 11 show a heat accumulator 1 with spiral flow paths 5. The arrangement of corrugated plates 8 has only been indicated in FIG. 10. These are, as shown, between the turns 18 and also between the outer turn 18 and the housing 11, which was not drawn. One collecting space 12 is located in the center of the heat accumulator 1 and the other collecting space 12 is arranged on the periphery of the storage core 6. The arrangement of the collecting spaces 12 can also be variable. Accordingly, another exemplary embodiment, not shown, has both collecting spaces 12 on the periphery of the storage core 6, although the flow paths 5 are guided spirally through the storage core 6 (see, for example, FIG. 3 in DE 41 41 556).

11 clearly shows that the flow paths 5 can also be designed to be variable in terms of their height H, h, in order to thereby also meet the requirement for a diverse design of the heat accumulator 1. These flow paths 5 should also preferably be formed from multi-chamber tubes 7. Here, the geometry of the turns 18 is different between the flow paths 5, but is identical within a flow path 5, that is, with a constant curvature. Other exemplary embodiments, not shown, which have spiral flow paths 5 could, for. 4, can also be designed such that the windings 18 are formed with different curvatures within a flow path 5 in order to be adapted to a constriction 15.

Reference list

1 heat storage

2 inlet

3 outlet

4 isolation

5 flow paths

6 memory core

7 multi-chamber pipe

8 heat-conducting elements (corrugated sheets)

9 rooms for the phase change material

10 waves

11 Housing of the memory core 6

12 meeting rooms

13 supports

14 outer housing

15 constriction

16 supernatant

17 bulge

18 turns

H Height of the flow paths 5 or the multi-chamber tubes 7

h lower height than H

Claims

claims

1. Heat storage, in particular latent heat storage, with thermal insulation, with at least one inlet and one outlet and collecting spaces for the heat transfer medium, which are fluidically connected to the storage core surrounded by a housing, are arranged in the flow paths (pipes) and the spaces between the flow paths , in which there is a phase change material, characterized in that the flow paths (5) consist of approximately oval or flat tubes which are guided in a wave shape through the storage core (6) and in that the spaces (9) for the phase change material between the individual flow paths (5) and between the shafts (10) of individual flow paths (5) and are at least predominantly covered with heat-conducting elements (8) which are metallically connected to the flow paths (5) and which are wavy, thin sheet metal strips which have a width which is larger than the large diameter of the flow w ege (5) forming tubes.

2. Heat storage, in particular latent heat storage, with thermal insulation, with at least one inlet and one outlet and collecting spaces for the heat transfer medium, which are fluidically connected to the storage core surrounded by a housing, are arranged in the flow paths (pipes) and the spaces between the flow paths , in which there is a phase change material, characterized in that the flow paths (5) consist of approximately oval or flat tubes which are spirally guided through the storage core (6) and in that the spaces (9) for the phase change material between the individual flow paths (5) and between the windings (18) of individual flow paths (5) and are at least predominantly covered with heat-conducting elements (8) which are metallically connected to the flow paths (5) and which are wavy, thin sheet metal strips which have a width which is larger than the large diameter of the flow gswege (5) forming tubes.

3. Heat accumulator, according to claim 1, characterized in that irregular wave heights and / or wavelengths are provided within a flow path (5) and / or between a plurality of flow paths (5).

4. Heat accumulator, according to claim 2, characterized in that the geometry of the turns (18) is irregular within a flow path (5) and / or between a plurality of flow paths (5).

5. Heat accumulator, according to the preceding claims, characterized in that the waves (10) or the windings (18) within a flow path (5) preferably in one

8th Run level and several flow paths (5) are preferably arranged approximately parallel to each other.

6. Heat accumulator, according to one of the preceding claims, characterized in that the heat accumulator (1) has a uniform outer shape and the flow paths (5) to it

Form are adapted.

7. Heat storage device according to one of the preceding claims 1 to 5, characterized in that the heat storage device (1) has bulges (17) or constrictions (15) or has a different shape from the uniform, for example cylindrical or cuboid, shape, and that the flow paths (5) (windings and / or waves) are adapted to the respective shape of the heat accumulator (1).

8. Heat storage device, according to the preceding claims, characterized in that the external heat-conducting elements (8) with the housing (11) of the storage core (6) are metallically connected.

9. Heat accumulator, according to at least one of the preceding claims, characterized in that the flat tubes forming the flow paths (5) are multi-chamber tubes (7).

10. Heat store, according to one of the preceding claims, characterized in that the collecting spaces (12) are approximately tubular.

11. Heat store, according to one of the preceding claims 1 to 9, characterized in that the collecting spaces (12) are approximately half-shell-shaped.

12. Heat storage device according to one of the preceding claims, characterized in that the collecting spaces (12) are arranged either within the insulation (4) or within the storage core (6).