GB2515069A

GB2515069A - Heat exchange apparatus

Info

Publication number: GB2515069A
Application number: GB1310505.1A
Authority: GB
Inventors: Jeremy Robins
Original assignee: JER INNOVATIONS Ltd
Current assignee: JER INNOVATIONS Ltd
Priority date: 2013-06-13
Filing date: 2013-06-13
Publication date: 2014-12-17
Anticipated expiration: 2033-06-13
Also published as: GB201310505D0; GB2515069B

Abstract

A heat exchanger 102 used to heat a fluid in a vessel 110, comprises a tube array having at least one tube 140 disposed within the vessel and communicating a fluid in use used to heat the fluid in the vessel. The at least one tube is flexible and in use is arranged to move when disposed within the vessel. Movement of the tube may comprise expansion due to pressurisation of fluid communicating through the tube or wherein in a first collapsed / folded state the tube is opened out to its in use state. The folded / collapsed state permits the tube to be inserted into a hole 114 in the vessel that would be too small if the tube were in the opened out in use state before insertion. The tube may be a single tube arranged in at least one coil 150, 152. A first and second coil may be used and arranged on the same axis. The tube may be a polymer (silicone) comprising a thermal conductive ceramic filler. The exchanger may be securely sealed 104 to the vessel and used in domestic or industrial hot water systems, in particular solar hot water systems.

Description

HEAT EXCHANGE APPARATUS

The present invention relates to a heat exchange apparatus, in particular to an apparatus for fluid-fluid heat exchange. The apparatus finds use, for example, in heating water as part of a solar thermal heating system.

Apparatus for exchanging heat between fluids are well known in the art and are used on a commercial scale in a wide range of processes. One very common apparatus for fluid-fluid heat exchange comprises a tube assembly.

One fluid is caused to flow through the tubes of the tube assembly, with a second fluid surrounding the tubes of the tube assembly. Heat exchange between the fluids takes place by heat transfer through the wall of the tubes of the tube assembly. One arrangement of this kind used on an industrial scale is the so-called shell and tube heat exchanger. Other tubular heat exchange assemblies are known for use on a range of different scales. A domestic hot water system typically employs a tube arranged in a coil within a tank, with hot water being passed through the heating coil to heat water surrounding the coil within the tank.

In general, tubular heat exchangers of the aforementioned general kinds employ assemblies of rigid tubes, with the tubes typically being formed from metal. Industrial scale tubular heat exchangers frequently employ tubes formed from steel, while domestic heating systems and the like typically employ tubes of copper, due to the higher heat transfer coefficient of copper and its ease of use.

CN 201 795698 discloses a heat exchange apparatus for use in source water heat pump systems. The heat exchange apparatus comprises overlapping coils of flexible polyethylene and polybutylene tubes.

US 4,605,059 discloses a heat exchanger. The heat exchanger comprises a plurality of coils of a fexible plastics material. The tubes of the coils are of differing diameters, with each coil being mounted coaxially about a coil of tubes of the next smaller diameter. The coils are supported on an array of longitudinally arranged slat members lying in spaced radial planes about the axis of the coil.

Surprisingly, it has been found that an improved heat exchange apparatus may be constructed with one or more heat exchange tubes that are flexible. It has been found that an apparatus with such flexible tubes offers significant advantages compared with known, rigid tube heat exchanger arrangements.

Accordingly, in a first aspect, the present invention provides a heat exchange apparatus comprising a tube array having one or more tubes for receiving a first heat exchange fluid, in use heat exchange occurring through the wall of each tube between the first heat exchange fluid within the tube and a body of a second heat exchange fluid surrounding the tube, wherein the tube is flexible.

In the present invention, the or each tube of the tube array of the heat exchange apparatus is flexible. In this respect, in one embodiment, the term flexible' is a reference to the tube being arranged to move within the body of the second heat exchange fluid, for example under the action of eddy currents occurring in the body of the second heat exchange fluid. In addition, it is preferred that the tube is sufficiently flexible that the diameter of the tube may be increased by increasing the pressure of the first heat exchange fluid within the tube within the range of normal operating pressures of the heat exchange apparatus and the system in which the apparatus is installed, the increase in fluid pressure increasing the internal diameter of the tube and reducing the thickness of the wall of the tube. In alternative embodiment, the term flexible' is a reference to the or each tube being capable of being folded, in particular into a retracted position, as described hereinafter.

The apparatus of the present invention is a heat exchange apparatus comprising one or more tubes. The one or more tubes may be arranged in any suitable pattern. In one embodiment, each tube is arranged in one or more coils. The one or more coils are preferably flat, that is with the tube forming the coil extending in substantially a single plane.

In a preferred embodiment, the apparatus comprises a single tube.

The single tube is preferably arranged in one or more coils, in particular the tube extending in a first coil and a second coil. Preferably, the first and second coils are arranged about substantially the same axis, most preferably both the first and second coils being flat, in particular with the first coil overlying the second coil.

The apparatus comprises an inlet for the first heat exchange fluid and an outlet for the first heat exchange fluid. In one embodiment, the tube array of the apparatus comprises a single tube extending between the inlet and the outlet. Alternatively, the tube array comprises a plurality of tubes extending between the inlet and the outlet. A header may be provided at the inlet for distributing first heat exchange fluid to each tube. Similarly, a header may be provided at the outlet, to collect first heat exchange fluid from each tube.

The one or more tubes of the apparatus are flexible, as described hereinbefore. Preferably, the apparatus comprises a support assembly for retaining the one or more tubes of the tube array. The support assembly retains the one or more tubes in a region within the body of the second heat exchange fluid, while allowing the one or more tubes to move within the second heat exchange fluid. In one embodiment, the support assembly comprises a support member, the support member having openings or apertures therein through which the or each tube extends.

The support assembly may comprise one or more support members.

In one embodiment preferred for its compactness, the support assembly comprises a single support member, preferably a generally elongate support member.

In one preferred embodiment, the or each tube is in the form of a coil, as noted above, in particular a flat coil. In one preferred arrangement, each coil extends laterally to either side of the support member, preferably with the support member extending through the central axis of the coil.

As noted above, the tube is arranged for indirect heat exchange through the wall of the tube between the first heat exchange fluid within the tube and the second heat exchange surrounding the tube. The heat transfer through the wall of the tube may be in either direction, that is from within the tube to the exterior or from the exterior of the tube to the fluid therewithin.

Preferably, the heat transfer is from the first heat exchange fluid within the tube to the second heat exchange fluid surrounding the tube. In this embodiment, the inlet of the apparatus is connected to a supply of hot first heat exchange fluid, with the outlet of the apparatus being connected to a cold return for the first heat exchange fluid.

The apparatus of the present invention may be used to effect heat transfer between a wide range of fluids. The apparatus is particularly advantageous when one or both of the first and second heat exchange fluids is liquid, more preferably when both heat exchange fluids are liquid. The apparatus may be used to effect heat exchange between any two liquids. In one preferred embodiment, the first heat exchange fluid is water and/or the second heat exchange fluid is water. The apparatus is of particular advantage in a heating system, especially a domestic hot water system, in which both the first and second heat exchange fluids are water, as described in more detail hereinafter. The water may contain one or more additives as typically employed in the art, for example to reduce corrosion or depress the freezing point of the liquid.

The material of the tube of the apparatus is flexible, while having a sufficient heat transfer coefficient to allow indirect heat exchange through the wall of the tube. The tube may be formed from any suitable material that provides the necessary properties including those of flexibility and heat transfer coefficient. Preferably, the tube is formed from a polymer, for example an elastomer. A particularly preferred material for forming the tube is silicone. Suitable silicone materials are known in the art and are commercially available.

A particularly preferred polymer, in particular silicone, is one comprising a filler to promote heat transfer through the polymer. Suitable fillers for this purpose include thermally conductive ceramic materials. Suitable thermally conductive ceramic fillers include metal nitrides, for example boron nitride, aluminium nitride, and carbides, for example silicon carbide. One suitable filler is micro-crystalline silica. Polymers containing such fillers are known in the art, in particular for use in encapsulating and mounting electrical components, where the combined properties of high electrical insulation and high heat transfer are required. Examples of such materials are disclosed in US 5,011,872. It is surprising to find that such materials are particularly effective for forming tubes for fluid/fluid heat transfer, in particular in the apparatus of the present invention.

The tube may have any suitable dimensions, the dimensions being determined by the operating requirements of the heat exchange apparatus.

The outer diameter of the tube may be from 1.0 to 100.0 mm, more preferably from 1.0 to 50.0 mm, still more preferably from 8.0 to 22.0 mm. An outer tube diameter of about 15 mm is particularly preferred for many applications, including for a domestic hot water system.

The tube may have any suitable wall thickness. The wall thickness will be determined by such factors as the pressure of the first heat exchange fluid during operation, the material used to form the wall of the tube and its heat transfer coefficient. Preferably, the wall thickness of the tube is in the range of from 0.2 mm to 20.0 mm, more preferably from 0.3 mm to 10.0 mm, still more preferably from 0.4 to 5.0 mm. One preferred wall thickness for the flexible tube is 0.4 mm, for use in a domestic hot water system.

The apparatus of the present invention finds general use in fluid/fluid heat exchange. One particularly advantageous use of the apparatus is in a system for providing hot water, in particular a domestic hot water system. In such a system, the first heat exchange fluid is typically water or an aqueous solution. The second heat exchange fluid is water, typically held in a tank.

Conventionally, such hot water systems comprise a coil of tubing, typically a coil of copper tube, disposed within the tank and connected to a source of hot water, such as a boiler or the like. The apparatus of the present invention may be installed in place of such a conventional heating coil.

Alternatively, the apparatus may be installed in addition to such a conventional heating coil. An example of such an arrangement arises when an existing hot water system, such as a domestic hot water system, is supplemented by the installation of a solar hot water system. Such a combined system is illustrated in Figure 1 and described in more detail hereinbelow.

The solar hot water system generally requires a second heating coil within the tank, such that the solar hot water system may operate independently of the conventional hot water system. A particular problem arises when installing a solar hot water system into a pre-existing hot water system. In particular, it is necessary to replace the existing tank, with its single heating coil, with a tank having installed therein two independent heating coils. In one embodiment, the apparatus of the present invention overcomes this problem and allows the existing tank with its single heating coil to be utilised.

As noted above, the tubes of the apparatus of the present invention are flexible and, in one embodiment, are free to move, for example under the action of eddy currents forming in the second heat exchange fluid surrounding the tubes. In a further embodiment, the or each tube is sufficiently flexible that it can be folded. This arrangement allows the tubes of the apparatus to be folded so as to be in a retracted position. In this way, the tube array of the apparatus may be introduced into an existing tank by way of an aperture or opening formed in the wall of the tank. Once inserted into the tank, the tubes of the tube array may be unfolded to an extended position, in which the tubes form the desired arrangement, such as one or more coils, for operation. In this way, the size of the aperture to be formed in the wall of the tank may be kept as small as possible, be of sufficient size only to introduce the tube array.

In a preferred embodiment, the or each tube of the apparatus is flexible, such that it is free to move, for example under the action of eddy currents forming in the second heat exchange fluid surrounding the tubes and is sufficiently flexible that it can be folded.

As discussed above, the apparatus preferably comprises a support assembly having one or more support members. As noted, a preferred compact embodiment comprises a single, generally elongate support member. In this embodiment, the support member is introduced into the tank, together with the tube array, through the aperture formed in the wall of the tank. The tubes of the tube array may be folded against the support member when in the retracted position, for introducing into the tank.

To secure the apparatus within the tank, the apparatus preferably comprises a mounting assembly. In one preferred embodiment, the mounting assembly secures the apparatus to the wall of the tank, in particular in the region of the aperture formed in the tank. Most preferably, the mounting assembly comprises means to provide a fluid-tight seal around the aperture, to prevent fluid entering or leaving the tank. Suitable seals include one or more 0-rings. In one embodiment, the mounting assembly comprises a first mounting member, for extending over the aperture against the inner surface of the wall of the tank, and a second mounting member for extending over the aperture against the outer surface of the wall of the tank. The tube array and the support assembly, if present, extend from the first mounting member within the tank, when installed. One or more fasteners are provided to fasten the first and second mounting members to each other. The inlet and outlet for the first heat exchange fluid are provided to extend through both the first and second mounting members.

In a further aspect, the present invention provides a method for installing a heat exchange apparatus in a vessel, the heat exchange apparatus comprising a tube array having one or more flexible tubes, the method comprising the steps of: forming an aperture in the wall of the vessel; providing the heat exchange apparatus with the tubes of the tube array in a retracted position; inserting the tube array into the vessel through the aperture; extending the tube array within the vessel; and mounting the heat exchange apparatus to the wall of the vessel.

In use, the tube array may be extended within the vessel by passing fluid through the tubes of the tube array. For example, the tubes of the tube array may be unfolded from the retracted position under the action of the first heat exchange fluid being supplied under pressure to the tubes of the tube array. The flexibility of the tubes of the tube array allow the tube array to be very compact when in the retracted position. This in turn allows the aperture in the vessel to be kept as small as possible.

It is an advantage of the apparatus of the present invention that it can be installed very low in a vessel, in particular in the base region of the vessel, especially adjacent the base of the vessel. This is of particular advantage when installing the apparatus in a vessel of an existing system, such as a domestic hot water system. Installation of the apparatus in the lower region or base region of the tank, in particular below an existing heating coil in the tank, provides for increased efficiency of the apparatus, especially when being used to install a solar hot water heating system into an existing conventional hot water system, as found in many domestic locations.

As noted above, a particularly preferred material for forming the tubes of the apparatus of the present invention is a polymer comprising a thermally conductive filler.

Accordingly, in a further aspect, the present invention provides a heat exchange apparatus comprising one or more tubes for providing indirect heat exchange between a first fluid within the tube and a second fluid surrounding the tube, the one or more tubes having a tube wall formed from a polymer composition comprising a thermally conductive filler dispersed in a polymer matrix.

In a preferred embodiment, the polymer composition comprises a silicone matrix.

Preferred thermally conductive fillers include thermally conductive ceramic materials, for example nitrides, such as boron nitride and aluminium nitride, and carbides, such as silicon carbide. A suitable filler is micro-crystalline silica.

In a further aspect, the present invention provides the use for indirect heat exchange between a first fluid and a second fluid of a thermally conductive polymer composition comprising a thermally conductive filler dispersed in a polymer matrix.

In a preferred embodiment, the polymer composition comprises a silicone matrix.

Advantages of employing flexible tubes in the tube array of the apparatus of the present invention have been described above. A further advantage arises in that the nominal diameter of the tubes of the tube array may be increased by increasing the pressure of the first heat exchange fluid within the tubes. An increase in the nominal diameter of the tube increases the total surface area of the tube available for heat exchange, while decreasing the thickness of the wall of the tube. Both effects increase the rate of heat transfer through the wall of the lube between the first and second heat exchange fluids.

As noted above, the heat exchange apparatus of the present invention finds many uses where indirect fluid/fluid heat transfer operations are required.

Accordingly, in a still further aspect, the present invention provides a system comprising a heat exchange apparatus as hereinbefore described.

In one preferred embodiment, the system is a hot water system, in particular a domestic hot water system.

The apparatus of the present invention finds particular use when used for the heating of a fluid, especially water, by way of solar thermal energy.

Accordingly, the present invention also provides a solar thermal hot water system comprising an apparatus as hereinbefore described.

Embodiments of the present invention will now be described, by way of example only, having reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a conventional domestic hot water system in combination with a solar hot water system; Figure 2 is a plan view of a heat exchange apparatus according to one embodiment of the present invention; and Figure 3 is a side view of the apparatus of Figure 2 in the direction of arrow A. Turning first to Figure 1, there is shown a diagrammatical representation of a domestic hot water system, generally indicated as 2. A domestic hot water system has been used in Figure 1 purely for illustrative purposes. It is to be understood that the overall arrangement and principles of operation of the system apply to other non-domestic and industrial systems, by analogy.

The system 2 comprises a generally cylindrical hot water tank 4 of known construction water to be heated is fed to the tank 4 through a cold water inlet 6 located in the base region of the tank. Water is heated in the tank 4 by indirect heat exchange with a heating fluid, as described below. Hot water is dispensed from the tank 4 by means of a hot water outlet 8 disposed in the top portion of the tank.

The tank 4 comprises a heating coil 10 formed from a coil of copper tube, of known and conventional configuration. The coil 10 receives hot water from a boiler 12 via a hot water feed line 14. The boiler may be any suitable means to heat water, for example a boiler powered by gas or oil. Water leaving the heating coil 10 is returned to the boiler via a hot water return line 16, in which is located a water pump 18.

In operation, water is heated by the boiler 12 and pumped through the heating coil 10. Water in the tank surrounding the heating coil 10 is heated by indirect heat exchange with the hot water within the heating coil 10. The operation of the boiler is controlled by a processor, for example in response to signal received from a thermostat sensing the temperature of the water in the tank 4, in known manner.

The system 2 comprises a second means to heat water within the tank.

In particular, the system 2 comprises a solar hot water panel 20, of known configuration, operable to heat a heat exchange fluid under the action of incident solar radiation. The heat exchange fluid may be water. The solar panel 20 is located in a suitable position to receive solar radiation, for example on the roof of the building. Such solar panels are known in the art and commercially available. Their installation and operation is similarly known in the art.

The tank 4 is further provided with a heat exchange apparatus 22 according to an embodiment of the present invention, details of which are described hereinafter. The heat exchange apparatus 22 is located in the base portion of the tank 4. This location provides the apparatus 22 with the greatest temperature differential between the hot fluid within the tubes of the apparatus 22 and the surrounding water, due to stratification of the water in the tank with the coldest water being located in the base of the tank.

Heat exchange fluid heated by the solar panel 20 is fed from the solar panel to the heat exchange apparatus 22 by a hot feed line 24. Heat exchange fluid is returned to the solar panel 20 via a return line 26 under the action of a fluid pump 28. An expansion vessel 30 is arranged in the return line 26, in known manner.

In operation, the heat exchange fluid is heated in the solar panel 20 and fed to the heat exchange apparatus 22 within the tank. Water within the tank 4 is heated by indirect heat exchange with the heat exchange fluid. A processor controls the operation of the pump 28, for example in response to signals from sensors measuring the temperature of heat exchange fluid in the solar panel and the temperature differential between the heat exchange fluid in the solar panel and the water within the tank 4. Again, such a control system and mode of operation is known in the art.

The tank 4 is provided with a further heating means, in particular an electrically powered immersion heater 32 of conventional design and operation.

As noted above, the system shown in Figure 1 comprises a heat exchange apparatus according to one embodiment of the present invention.

The apparatus, generally indicated as 102, is shown in Figures 2 and 3.

Referring to Figures 2 and 3, the heat exchange apparatus 102 comprises a mounting assembly 104 having a first or outer mounting member 106 and a second or inner mounting member 108. In use, the apparatus 102 is installed in a tank, generally indicated as 110, with the first mounting member 106 is disposed about an aperture 114 formed in the wall 112 of the tank 110. The second mounting member 108 is similarly mounted on the interior of the tank 110, against the inner surface of the wall of the tank 110. A suitable waterproof seal, such as an 0-ring, is disposed about the aperture 114, to prevent fluid entering or leaving the tank 110 through the apertures 114.

The apparatus 102 is provided with an inlet pipe 120 for a first heat exchange fluid, in particular water, and an outlet pipe 122 for the first heat exchange fluid, both of which extend from the outer mounting member 106 and through the inner mounting member 108.

An elongate support member 130 extends from the inner mounting member 108, being secured to a boss 132 extending from the inner mounting member. As shown in Figure 3, the support member 130 is provided with a plurality of openings 134 arranged in an upper row 136 and a lower row 138, the openings in each row being divided between two portions at opposing ends of the support member, with a central portion in each row without openings.

The apparatus 102 further comprises a flexible tube 140. A first end 142 of the tube 140 is connected to the inlet pipe 120. A second end 144 of the tube 140 is similarly connected to the outlet pipe 122. The tube 140 is arranged to form an upper coil 150 and a lower coil 152, with the loops of the upper coil 150 passing through the openings 134 in the upper row 136 of the support member, while the loops of the lower coil 152 pass through the openings 134 in the lower row 138 of the support member.

As noted above, the first and second ends 142, 144 of the tube 140 are connected to the inlet and outlet pipes 120, 122. In particular, the end portions of the tube are fitted over the respective inlet and outlet pipes. A clamp 156 is applied over the end portions of the tube 140 around the outlet pipes 120, 122 and secured by way of bolts 158. The clamp 156 is removable, allowing the tube 140 to be replaced, should this be necessary.

The tube 140 is formed from silicone rubber containing a thermally conductive ceramic filler.

The apparatus 102 may be installed in an existing hot water tank as follows: An aperture is cut in the wall of the tank at the appropriate location for the apparatus. In the case of an existing hot water system of conventional arrangement, as shown in Figure 1, the apparatus 102 for use with a solar thermal hot water system is installed in the tank in the region of the base of the tank below the existing coil.

The tube 140 is folded against the support member 130. The tube 140, support member 130 and the inner mounting member 108 are passed through the aperture in the tank wall. The inner mounting member 108 is arranged within the tank to extend around the aperture. The outer mounting member 106 is arranged on the exterior of the tank around the aperture and fastened to the inner mounting member 108, to sandwich a portion of the wall of the tank therebetween and form a fluid-tight seal. One or more 0-rings may be provided to ensure a fluid-tight seal around the aperture in the tank wall.

Bolts 160 are provided to fasten the inner mounting member 108 to the outer mounting member 106, as shown in Figure 3.

As shown in Figures 2 and 3, the apparatus 102 is arranged in the tank such that the coils 150, 152 of the tube 140 extend substantially horizontally and laterally on either side of the support member 130.

The inlet pipe 120 and the outlet pipe 122 are connected to the solar hot water system as shown in Figure 1 and described above, such that water heated in the solar thermal panel is provided under pressure to the tube 140.

The initial action of the pressurised water is to inflate the tube 140 and extend the coils 150, 152 on either side of the support member 130 and into the position shown in Figures 2 and 3.

In use, heat exchange occurs through the wall of the tube 140 between the hot water within the tube and the water in the tank surrounding the apparatus 102. The tube 140 is sufficiently flexible to be able to move within the surrounding water under the action of eddy currents formed within the tank, while being generally retained in position by the support member 130.

The performance of the apparatus 102 is illustrated by the following

Example.

EXAMPLE

To demonstrate the effectiveness of the apparatus of the present invention, an experiment was conducted to compare the heat transfer efficiency of an apparatus having the general configuration shown in Figures 2 and 3 in heating a body of water held in a tank with that of a conventional coil of copper tube.

The apparatus of the present invention comprised a tube formed from silicone comprising a thermally conductive ceramic filler. The tube had the following dimensions: Length: 7000 mm Outer Diameter: 22 mm Wall thickness: 0.4 mm The copper coil comprised a copper tube having the following dimensions: Length: 5000 mm Outer Diameter: 22 mm Wall thickness: 1.6 mm The silicone tube employed was obtained from Polymax Ltd, UK and comprised micro-crystalline silica as a filler dispersed in a silicone matrix.

The water in the tank was heated to a temperature of 20°C. Hot water was provided to each tubular coil at a flow rate of 2 litres/minute. The temperature of the hot water at each of the inlet (Tin) and the outlet (Tout) of the tubular coil was recorded. The temperature (T) of the water in the tank was also measured. The heat transfer Q achieved in the apparatus was calculated using the following formula: Q=mxCxaT where m is the mass flowrate of water through the tube, C, is the specific heat capacity of the water and AT is the temperature difference of the water at the inlet and the outlet of the coil.

The results are set out in the following Table 1.

Table 1

Copper Tube Apparatus of Figures 2 and 3 Tin Tout T Q Tin Tout T Q (°C) (°C) (°C) (J/kg s) (°C) (°C) (°C) (J/kg s) 52 24 20 3907 47 22.9 20 3364 51 24.7 21 49.8 24.0 21 51.9 25.5 22 49.8 24.8 22 53 26.3 23 3727 49.7 25.5 23 3378 53 27.1 24 49.8 26.3 24 52.9 27.8 25 49.7 27.1 25 52.8 28.5 26 3392 50.1 27.9 26 3099 52.8 29.2 27 50.4 28.7 27 52.4 30.2 28 49.4 29.3 28 52.5 30.8 29 3030 50.4 30.1 29 2834 52.6 31.8 30 50.1 30.9 30 52.8 32.4 31 50.7 31.9 31 53.1 33.3 32 2764 50.8 32.9 32 2499 52.5 34.0 33 49.9 33.5 33 52.8 34.8 34 50.2 34.2 34 52.7 35.3 35 2429 50.8 35.0 35 2206 As can be seen, the apparatus of the present invention, with a flexible tube coil formed from a silicone impregnated with a ceramic filler provided a comparable heat transfer performance to a conventional copper coil.

Claims

CLAIMS1. A heat exchange apparatus comprising a tube array having one or more tubes for receiving a first heat exchange fluid, in use heat exchange occurring through the wall of each tube between the first heat exchange fluid within the tube and a body of a second heat exchange fluid surrounding the tube, wherein the tube is flexible.
2. The apparatus according to claim 1, wherein the or each tube is sufficiently flexible such that it is free to move under the action of eddy currents forming in the second heat exchange fluid surrounding the tubes.
3. The apparatus according to either of claims 1 or 2, wherein the tube is sufficiently flexible that the diameter of the tube may be increased by increasing the pressure of the first heat exchange fluid within the tube within the range of normal operating pressures of the heat exchange apparatus and the system in which the apparatus is installed, the increase in fluid pressure increasing the internal diameter of the tube and reducing the thickness of the wall of the tube.
4. The apparatus according to any of claims 1 to 3, comprising a single tube.
5. The apparatus according to any preceding claim, wherein one or more of the tubes is arranged in at least one coil.
6. The apparatus according to claim 5, wherein the at least one coil extends in substantially a single plane.
7. The apparatus according to either of claims 5 or 6, where in the one or more tubes extends in a first coil and a second coil.
8. The apparatus according to claim 7, wherein the first coil and the second coil are arranged about substantially the same axis.
9. The apparatus according to any preceding claim, further comprising a support assembly for retaining the one or more tubes of the tube array.
10. The apparatus according to claim 9, wherein the support assembly comprises a support member, the support member having openings therein through which the or each tube extends.
11. The apparatus according to either of claims 9 or 10, wherein the support assembly comprises a single elongate support member.
12. The apparatus according to claim 11, wherein the or each tube is arranged in a coil extending about an axis, the support member extending through the axis.
13. The apparatus according to any preceding claim, wherein the or each tube is formed from a polymer.
14. The apparatus according to claim 13, wherein the polymer is a silicone.
15. The apparatus according to either of claims 13 or 14, wherein the polymer comprises a filler for promoting heat transfer through the polymer.
16. The apparatus according to claim 15, wherein the filler comprises a thermally conductive ceramic material.
17. The apparatus according to claim 16, wherein the thermally conductive ceramic material comprises a metal nitride, a carbide, silica, or a mixture thereof.
18. The apparatus according to any preceding claim, wherein the one or more tubes are foldable into a retracted position from which they may be unfolded into an extended position.
19. The apparatus according to any preceding claim, further comprising a mounting assembly.
20. The apparatus according to claim 19, wherein the mounting assembly is for securing the apparatus to the wall of a tank.
21. The apparatus according to claim 20, wherein the mounting assembly comprises a first mounting member for extending over an aperture in the wall of the tank against the inner surface of the wall and a second mounting member for extending over the aperture against the outer surface of the wall.
22. A method for installing a heat exchange apparatus in a vessel, the heat exchange apparatus comprising a tube array having one or more flexible tubes, the method comprising the steps of: forming an aperture in the wall of the vessel; providing the heat exchange apparatus with the tubes of the tube array in a retracted position; inserting the tube array into the vessel through the aperture; extending the tube array within the vessel; and mounting the heat exchange apparatus to the wall of the vessel.
23. The method according to claim 22, wherein the heat exchange apparatus is as claimed in any of claims 1 to 21.
24. The method according to either of claims 22 or 23, wherein the vessel is a hot water tank.
25. The method according to claim 24, wherein the heat exchange apparatus is comprised in a solar hot water system.
26. A heat exchange apparatus comprising one or more tubes for providing indirect heat exchange between a first fluid within the tube and a second fluid surrounding the tube, the one or more tubes having a tube wall formed from a polymer composition comprising a thermally conductive filler dispersed in a polymer matrix.
27. The apparatus according to claim 26, wherein the filler comprises a thermally conductive ceramic material.
28. The apparatus according to claim 27, wherein the thermally conductive ceramic material comprises a metal nitride, a carbide, silica, or a mixture thereof.
29. The apparatus according to any of claims 26 to 28, wherein the polymer matrix comprises a silicone.
30. Use for indirect heat exchange between a first fluid and a second fluid of a thermally conductive polymer composition comprising a thermally conductive filler dispersed in a polymer matrix.
31. A system comprising a heat exchange apparatus as claimed in any of claims ito 21 or claims 26 to 29.
32. The system according to claim 31, wherein the system is a hot water system.
33. The system according to claim 32, wherein there system is a solar thermal hot water system.
34. A heat exchange apparatus substantially as hereinbefore described having reference to any of Figures 1 or Figures 2 and 3.
35. A method of installing a heat exchange apparatus substantially as hereinbefore described having reference to any of Figures 1 or Figures 2 and 3.
36. A hot water system substantially as hereinbefore described having reference to any of Figures 1 or Figures 2 and 3.
37. A solar hot water system substantially as hereinbefore described having reference to any of Figures 1 or Figures 2 and 3.