GB2223567A

GB2223567A - Heat exchange system

Info

Publication number: GB2223567A
Application number: GB8820145A
Authority: GB
Inventors: Kenneth Frank Ridley
Original assignee: BOLERO RINKS Ltd
Current assignee: BOLERO RINKS Ltd
Priority date: 1988-08-25
Filing date: 1988-08-25
Publication date: 1990-04-11
Anticipated expiration: 2008-08-25
Also published as: GB8820145D0; GB2223567B

Abstract

A heat exchange system comprises an integral water impervious sheet including a plurality of pairs of tubes (1, 2) spaced one pair from the next by impervious webs. A first one (1) of each pair is, in use, above a second one (2) of the pair. Means are provided to feed heat exchange medium to a first end of one (1) of each pair, and also to remove heat exchange medium from a first end of the other (2) of each pair. Means connect together second ends of each paid to enable return flow. Each sheet can be attached to one or both adjacent sheets by water impervious seal means (3). The above heat exchange system, when a refrigeration system, enables an ice rink to be laid easily and quickly even by unskilled labour. <IMAGE>

Description

HEAT EXCHANGE SYSTEM The present invention relates to a heat exchange system. More particularly but not exclusively, it relates to a heat exchange system which may be set up and dismantled quickly and easily to provide a large heat exchange surface.

The present invention was developed originally for providing flows of cooling liquid for use in preparing ice rinks and the like. However, it is equally applicable for use where the heat exchange medium is a hot fluid. For the sake of convenience, the present invention will be described in respect of its refrigerating function but, as stated above, it is not intended to exclude any heating functions.

In the past, ice skating rinks have usually been formed using large diameter metal pipes at relatively large spacings spread across the width of an ice skating rink and connected at each of their ends to a header pipe. The pipes were embedded in concrete to form a base for the ice skating rink and a refrigerating medium such as brine or ethylene glycol was pumped through the pipes from one header to the other. This is not entirely satisfactory since at the input side of the rink, the ice is at a much lower temperature than at the refrigerant output side of the rink. Furthermore, the large spacing between pipes meant that the ice immediately above the pipe was colder than the ice in the zones between the pipes.

In an attempt to overcome one of the above disadvantages, both headers were placed on one side of the rink and the pipes were connected one to the next at the other side, whereby alternate pipes gave flow and the others return. While this helped to average the ice temperature, it was not entirely successful because of the spacing of the pipes. Furthermore, this system is only applicable to permanently set up ice rinks.

In another attempt to overcome these problems, it has been proposed to provide a mat of comparatively small diameter flexible tubes, again with alternate flow and return tubes connected at their far ends. Ideally, the tubes should be spaced closely together to help in equalising the ice temperature and with a mat of flexible tubes, this is not always easy. Furthermore, when using such a mat in a "temporary" ice rink, where the mat is laid on top of an impervious surface, it has been found necessary to surround the tubes with sand or similar material to act as a thermal bridge. Dismantling of the rink after any temporary use entails removal of what is by then very wet sand. Furthermore, in temporary situations, the area beneath the mat of tubes must be water impervious.

Another disadvantage with this system is that the process of laying a multitude of small pipes, fixing to the floor, and covering with sand, is a labour intensive activity requiring a certain degree of specialist knowledge and skill.

It is an object of the present invention to provide a heat exchange system, especially a refrigeration system, which overcomes the above disadvantages and enables an ice rink or other heat exchange zone to be laid easily and quickly by even unskilled labour.

According to the present invention there is provided a heat exchange system comprising an integral water impervious sheet including a plurality of pairs of tubes spaced one pair from the next by impervious webs, a first one of each pair being, in use, above a second one of the pair, means to feed heat exchange medium to a first end of one of each pair, means to remove heat exchange medium from a first end of the other of each pair, and means connecting together-second ends of each pair.

Preferably each sheet can be attached to one or both adjacent sheets by water impervious seal means.

Advantageously, each sheet is approximately 1 metre wide and of any desired length, and is provided with a pair of headers and a return gallery, each of appropriate width.

Each tube is preferably of small bore and substantially elliptical in cross-section, having their major axes extending across the sheet.

The means for feeding and removing heat exchange medium may comprise an elongate plenum chamber sealingly divided longitudinally into two vertically separated compartments by said sheet, the tubes of wench pair each communicating with a respective compartment of said plenum chamber, said plenum chamber having two ports, one adapted to communicate with each compartment.

The means connecting together said second ends may comprise a plenum chamber adapted to be shaped in cross-section to combine with an end of said sheet to form a venturi constriction in the flow path between one and the other tube of each pair.

The tubes are preferably of a semi-rigid polymeric material, such as EVA.

The tubes and interconnecting webs may be formed as an extrusion to any desired length.

The heat exchange medium may be a refrigerant liquid and the sheets, when laid together, form part of the base of an ice rink. In this case, the incoming refrigerant is fed to the upper of each pair of tubes for immediate contact with the ice or water and the warmer outgoing refrigerant is removed from the lower of each pair.

The refrigerant is preferably ethylene glycol.

Alternatively, the heat exchange medium may be hot water or other liquid, when the sheets, when laid together, may form a cover for a sports pitch or track or may form a sub-soil heating system.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 is a cross-section through a sheet embodying the present invention; FIGURE 2 is a plan view of a number of sheets laid out for use and connected to their respective headers and return galleries; FIGURE 3 is a side elevation, shown schematically, of a sheet with associated headers and return gallery; FIGURE 4 shows in more detail the header system; FIGURE 5 shows in more detail the return gallery; FIGURE 6 shows a means to join lengths of tube, should it be needed; FIGURE 7 shows an alternative embodiment using separated sheets on an impervious base; FIGURE 8 is a similar cross-section to that in Figure 7 but showing an alternative method of joining sections of base together;; FIGURE 9 shows an alternative embodiment of sheet; FIGURE 10 shows a further alternative embodiment of sheet; and FIGURE 11 shows yet another alternative embodiment of sheet.

Referring now to the drawings, which will be described in respect of the use of the system for preparing an ice skating rink, there is shown in Figure 1 one sheet of heat exchange tubes. The sheet is approximately 1 metre across and of any desired length. The tubes are elliptical in cross-section with their major axes extending across the sheet. The upper tubes 1 carry the flow of refrigerant from a header while the lower tubes 2 carry the return flow back to another header. Because of the elliptical shape of the tubes, almost the entire upper surface of the sheet can extract heat from the water above to freeze it. The close vertical proximity of the flow and return tubes causes an averaging of the temperature of the refrigerant over the majority of the sheet surface.

At each edge of the sheet is provided a sealing abutment 3 extending longitudinally of the sheet. As can be seen, the abutments 3 at each side of the sheet are oppositely directed to cooperate with an abutment on the adjacent sheet. Furthermore, since the sheet is symmetrical, with oppositely facing abutments, its orientation is not vital although once the return gallery is attached, there is a preferred orientation.

The sheet is formed as a continuous extrusion of semi-rigid plastics material, such as EVA, and can be cut to any desired length. Preferably the spacing of tube centre lines is 25 mm so that there are approximately 40 tube pairs in any sheet.

Referring now to Figure 2, there is shown an assembly of sheets forming the base of an ice skating rink.

Each sheet 4 is provided with its return gallery 5 and its header pair 6. The return galleries and headers will be described in more detail below. For the present, as can be seen from Figure 2, each header 6 is joined to a flow pipe 7 and a return pipe 8. These are connected through a conventional refrigeration plant.

Figure 4 shows a header 6. The header 6 comprises an elongate casting or similar construction of the same width appróximately as each sheet. A plenum chamber is divisible into two compartments 9 and 10 by insertion of one end of the sheet. Prior to its insertion, holes are made in opposite surfaces of the sheet either by individually punching holes in each tube or by cutting a groove across the tubes such that apertures 11 and 12 communicate from the tubes to respective compartments 9 and 10. The openings through which the sheet is inserted are preferably shaped to be undular to conform more or less exactly with the shape of the sheet.When the sheet has been inserted through both walls of the plenum chamber, end plugs 13 are placed in the end of each tube and then both sides of the header are encapsulated in plastics material 1-. In each header is an inlet port 15 and an outfit port 16. The direction of flow is as indicated by the arrows with refrigerant entering through inlet port 15, passing along the sheet and back again to exit finally through outlet port 16.

Referring now to Figure 5, there is shown a cross-section of the return end of the tubes with a return gallery 5 having a generally semi-circular internal shape. Again, the sheet is inserted into the semi-circular end with both top and bottom surfaces cut away leaving a centre dividing surface 17 of the sheet protruding. This protrusion combined with the shape of the return gallery 5 causes a slight venturi effect in zone 18. The venturi effect speeds the refrigerant flow through this point and returns it to the return pipes 2. The return gallery 5 is shaped in its lower part to slow down this flow again to maintain equilibrium conditions. The sheet is secured within the return gallery 5 by means of an encapsulating plastics material 19.The gallery 5 may extend across the whole width of the sheet so that flows may, to a small extent, mix within the gallery, or it may be provided with ribs to separate the flows of each pair of tubes from those of adjacent pairs of tubes.

If it should become necessary to join lengths of sheet, there is shown in Figure 6 a method of doing so.

Elliptical tubes 20 of comparatively thin metallic material, e.g. copper, are inserted into the end of each tube of one sheet, and then the corresponding ends of each tube of the next sheet. The upper and lower surfaces of the sheets can be welded together at 21 to prevent any outward leakage of refrigerant. It is not possible easily to weld the join at 22, but this is less important since the only leakage occurring would be between the flow and return passages of the refrigerant, and any leakage amount would be small.

An alternative embodiment is shown in Figure 7 in which the sheets are narrower, possibly as small as four pairs of tubes and there is no seal between adjacent sheets. In this case, the sheets are laid in a tray having upstands 23 between each sheet. The tray 24 may be of fibreglass reinforced plastics material or the like and be produced in sections adapted to be sealed one to the next.

Alternative sealing means are shown in Figures 7 and 8.

Figures 9,10 and 11 show alternative arrangements of sheet. In Figure 9 the flow and return tubes are each conventional tubes but are enshrouded within two sheets of plastics material welded together between the pairs of tubes. In Figure 10, the conventional cylindrical tubes are replaced by elliptical cross-section tubes, but otherwise it is the same. In Figure 11, the sheet is formed of three layers of plastics sheet material welded together intermittently so that the intervening portions form pairs of passageways.

In order to lay an ice skating rink, there are first laid optionally a layer of insulation material and a water impervious sheet. These are preferable, but not essential, since the sheets of the invention attach sealingly one to the- next to prevent water penetrating below the sheet. The sheets are then laid and sealed one to the next with return galleries and headers already attached. It is thus a matter of moments to lay a large expanse of heat transfer surface. Once the sheets are laid, connections are made to the headers and water sprayed over the surface. As the refrigerant flows through the tubes, the water freezes to form a layer of ice.

As can be seen, there is no need for a sand thermal bridge, due to the very close proximity of the tubes carrying the refrigerant. The configuration of the pairs of tubes, one above the other, allows for the maximum surface area of the flow of refrigerant to be presented to the ice such that the lowest temperature of refrigerant is in contact with nearly 1008 of the underside of the ice.

Similarly, the configuration of the tubes one above the other, allows for a 100% surface area contact of the lowest temperature coolant with that of the higher temperature return coolant. Thus the cooling temperature is averaged over the entire ice rink. This reduction in the differential temperature permits lower operating costs due to lower flow rates, thus allowing use of smaller pumps, use of lower rated compressors, and quicker response to changing ambient temperatures and to varying demands of the ice user.

Installation time for both permanent and temporary ice rinks is considerably reduced by the simplicity of joining each sheet over the length of the rink and its connection to the flow and return of coolant.

There is also no need for a sand thermal bridge between tubes.

As well as its use in creating ice skating rinks, the system of the present invention may find use in floors for cold rooms, e.g. cold storage, or in cooling hot environments such as foundries. It may also be placed on roofs to keep flat roof buildings cool in hot countries.

Given the flexibility of the sheets, they may be wrapped around pipework or industrial vessels rather than being laid flat, to cause cooling thereof. The sheets may also be laid on an angled base to form slides and toboggan runs or even ski jumps.

Conversely, when used with a hot fluid, the system may be used for under floor heating, to keep flat roofs clear of frost and snow, or for heating pipework and industrial vessels. The systems could also be used for covering sports pitches and tracks to keep them clear of frost and snow, or may even find use as an under-soil heating system.

Claims

CLAIMS:

1. A heat exchange system comprising an integral water impervious sheet including a plurality of pairs of tubes spaced one pair from the next by impervious webs, a first one of each pair being, in use, above a second one of the pair, means to feed heat exchange medium to a first end of one of each pair, means to remove heat exchange medium from a first end of the other of each pair, and means connecting together second ends of each pair.

2. A system as claimed in claim 1, wherein each sheet can be attached to an adjacent sheet by water impervious seal means.

3. A system as claimed in either of claim 1 or claim 1, wherein the or each sheet is approximately 1 metre wide and of any desired length, and is provided with a pair of headers and a return gallery, each of appropriate width.

4. A system as claimed in any one of the preceding claims, wherein each tube is of small bore and substantially elliptical in cross-section, having major axes extending across the sheet.

5. A system as claimed in any one of the preceding claims, wherein the means for feeding and removing heat exchange medium comprises an elongate plenum chamber sealingly divided longitudinally into two vertically separated compartments by said sheet, the tubes of each pair each communicating with a respective compartment of said plenum chamber, said plenum chamber having two ports, one adapted to communicate with each compartment.

6. A system as claimed in any one of the preceding claims, wherein the means connecting together said second ends comprises a plenum chamber adapted to be shaped in cross-section to combine with an end of said sheet to form a venturi constriction in the flow path between one and the other tube of each pair.

7. A system as claimed in any one of the preceding claims, wherein the tubes are of a semi-rigid polymeric material, such as EVA.

8. A system as claimed in claim 7, wherein the tubes and interconnecting webs are formed as an extrusion to any desired length.

9. A system as claimed in any one of the preceding claims, wherein the heat exchange medium is a refrigerant liquid and the sheets, when laid together, form part of the base of an ice rink.

10. A system as claimed in claim 9, wherein the incoming refrigerant is fed to the upper of each pair of tubes for immediate contact with the ice or water and the warmer outgoing refrigerant is removed from the lower of each pair.

11. A system as claimed in either claim 9 or claim 10, wherein the refrigerant is ethylene glycol.

12. A system as claimed in either claim 9 or claim 10, wherein the refrigerant is brine.

13. A system as claimed in any one of claims 1 to 8, wherein the heat exchange medium is hot water or other liquid, and the sheets, when laid together, form a cover for a sports pitch or track or may form a sub-soil heating system.

14. A heat exchange system substantially as described herein with reference to the Figures of the accompanying drawings.