WO2000070286A1

WO2000070286A1 - Heat transfer system, particularly for use in the heating or cooling of buildings

Info

Publication number: WO2000070286A1
Application number: PCT/GB2000/001781
Authority: WO
Inventors: Leo Lamb
Original assignee: Stefanini, Daniel
Priority date: 1999-05-14
Filing date: 2000-05-15
Publication date: 2000-11-23
Also published as: AU5081800A

Abstract

A heat transfer system (2) comprising a conduit (6) for transporting a heat transfer medium and an at least partially evacuated self-contained unit (4) in contact with the conduit, the unit having an interior cavity (12) for receiving a fluid whereby heat is transferred to or from the heat transfer medium from or to the fluid in the unit. The system may comprise a series of upright heatpipes in contact with a water pipe, the heatpipes being housed within a manifold.

Description

Title: HEAT TRANSFER SYSTEM , PARTICULARLY FOR USE IN THE HEATING OR COOLING OF BUILDINGS

DESCRIPTION

The present invention relates to an improved heat transfer system, particularly but not exclusively for use in the heating or cooling of buildings.

The transfer of heat energy is used in a wide variety of applications, such as for heating buildings and in the supply of hot water, both domestically and industrially. A number of systems exist for heating a building, such as a hot water or gas heating systems. A hot water heating system uses water as the medium for transporting heat around a building. The water is heated in a boiler and is delivered via pipes to radiators situated at intervals throughout the building. The system may rely on gravity for the movement of the water through the system, i.e., the heated water becomes less dense and rises up the pipes and is delivered to radiators as it flows back down through the pipes or alternatively an electric pump may be installed in either the flow pipe or return pipe to pump the hot water around the system. The flow of hot water through the radiators results in the release of heat therefrom by means of radiation, convention, and conduction thereby heating the surroundings of the radiator.

The temperature conveyed by a hot water heating system may be controlled by means of a central thermostat set to a desired temperature. When the actual temperature of the system rises above or falls below the desired temperature the flow of hot water to the radiators or the firing of the boiler is adjusted accordingly. The temperature of the radiator may also be adjusted by means of a separate thermostat provided on the radiator.

Although the aforementioned system does provide a satisfactory means of heating a building, the overall use of energy is wasteful, requiring a great deal of energy to be expended in heating and maintaining the temperature of the water and pumping it around the building and then along convoluted pipes contained within each radiator provided in a building. The pipes and radiators are also subject to the build up of pressure which, although rare, can result in a pipe bursting.

Further disadvantages associated with conventional heating systems are that the

radiators are bulky and expensive. The radiators are also difficult to move once installed in a particular location due to the main water pipes being provided with auxiliary pipework for the delivery of water to the radiator in the regions where radiators are to be located in a particular building. Thus, changing the positioning of a radiator would require substantial alterations to the pipework of the system. The heavy nature of the radiator dictated by the radiator having to potentially withstand high pressures also means that the radiator has to be fixed to a wall by substantial fastening means resulting in the radiator being difficult to remove at a later date. Thus, the

provision of a heating system which uses conventional radiators having convoluted pipes contained within the body of the radiator generally restricts the positioning of the radiator to the location it was originally installed.

Generally, radiators are heated by one particular type of heat source, such as a gas boiler or electricity. This can lead to problems if the source of heat breaks down since it will no longer be possible to heat the radiators. Additionally, radiators are normally of a standard size and heat up over their entire surface. If anything should go wrong with the radiator, the whole unit is effected and has to be repaired or replaced. It is an object of the present invention to provide an improved heat transfer system, particularly for the heating or cooling of buildings, which aims to overcome the abovementioned drawbacks.

Accordingly, the present invention provides a heat transfer system comprising a conduit for transporting a heat transfer medium and an at least partially evacuated self-contained unit in contact with the conduit, the unit having an interior cavity for receiving a fluid whereby heat is transferred to or from the heat transfer medium to or from the fluid in the unit.

Preferably, the conduit is in the form of a pipe. The heat transfer medium may

be, for example, water or gas. Preferably, the pipe transports water around a building which has been heated by means of a boiler. Alternatively the conduit may be in the form of an electric pipe, the pipe being heated, for example by means of coils around the pipe.

The unit is preferably in the form of a radiator, for example being a rectangular block having an interior cavity. The unit may be provided with means for introducing a specified amount of fluid into the cavity for absorbing the heat from the heat conductmg medium and means, such as a valve, for partially evacuating the interior of

the unit after insertion of the fluid.

Preferably, the lower edge of the unit is provided with a concave profile to abut

against the convex profile of the pipe. Releasable fastening means, such as straps, may be provided for attaching the unit to the pipe. However it is to be appreciated that the unit may completely surround the pipe, albeit the unit is still a discrete unit to prevent mixing of the contents of the pipe and unit. Additional releasable fastening means may be provided for attaching the unit to a surface, such as a wall. Preferably, the unit is provided with a magnetic fastening for attaching to a complimentary fastening provided on the surface.

The radiator may be formed of a single rectangular block or may be formed, for example, of two panels. The panels may be readed. Alternatively, the unit may be constructed to resemble a skirting board wherein the unit is placed on low level pipes, thereby hiding the pipes and providing a heating system that is not detrimental to the appearance of a room.

It is to be appreciated that the radiator unit may be made in any suitable shape and size but be such that a part thereof may abut the pipe transporting the heat- conducting medium.

The system may also be used to provide underfloor heating or cooling. For example, longitudinal units may be provided for resting at intervals on pipework that is provided under the floor. Preferably, the longitudinal unit is made up of a series of separate units that are linked together, for example by soldering. The units may be made of a T-joint, the leg of the T-joint having an inverted semi T-joint attached thereto to provide a foot having a curved inner profile for placing on the under floor piping. The opening between the main T-joint and the foot is sealed using suitable means and the unit is provided with means for evacuation thereof and for introduction of the working fluid. Multiple units may be connected together by, for example, welding adjacent connectors that extend laterally from the head of each T-joint. Reducers are preferably included between adjacent heads so that any fluid in the unit drains into the heads and does not collect in the connector. The respective ends of the units are preferably capped and blanked. In this manner, the units which may be provided in various lengths and sizes, may be placed at intervals on the under floor piping. The increased surface area provided by the units results in a greater amount of heat being transferred to or from the space above than if heating or cooling was effected by means of the piping alone.

In an alternative embodiment of the present invention, the unit is comprised of one or more heatpipes that are placed in contact with the conduit transporting the heat transfer medium. More preferably, the individual heatpipes are contained within a manifold that is attached to the conduit, the manifold having a plurality of channels for receiving the heatpipes. Alternatively, a longitudinal element may be provided for surrounding or contacting the heating element, the longitudinal element being provided

with means for supporting the individual heatpipes. For example, the element may have an upwardly open bracket along the length thereof or a series of brackets extending upwardly therefrom for receiving the heatpipes to keep the heatpipes in contact with the heating element. The longitudinal element is preferably in the form of an extrusion.

It is preferable to provide a casing over the unit. More preferably, the casing is provided with lower and upper airflow holes to allow air to enter the bottom of the unit and leave through the upper airflow holes thereby enabling the unit to transfer heat by

means of convection and radiation. Preferably, a fan is provided within the casing to assist in circulation of the air. The casing may be formed integrally with the heatpipes. It is to be appreciated that the system may be used to effect cooling of the surroundings by supplying warm air to the heatpipes wherein the warm air transfers its heat energy to the working fluid in the pipes and thereby cools the air which is then released from the unit. The ability of the system to work as a heating or cooling system would be dictated by the temperature of the heatpipes compared with the temperature of the surroundings.

The unit may be provided with a secondary heat source whereby if the heat- conducting medium in the conduit should fail, the heatpipes may still be heated to effect heating of the radiator and the surroundings. For example, an electrical heating

element may be attached to the heatpipes for connection to an electrical supply, when

required.

The unit may be made of any appropriate heat conducting material, such as aluminium or steel. The interior cavity of the unit is preferably provided with strengthening elements to prevent the collapse thereof under vacuum, particularly in embodiments having a large interior cavity. For example, the cavity may be provided with rings of stiffening tubes at spaced apart intervals.

The unit may be placed on a subsidiary pipe which branches off the main pipe. Preferably, a tap is provided to open and close the entrance to the subsidiary pipe.

For a better understanding of the present invention and to show more clearly how it may be carried in to the effect, reference will now be made by way of example

only, to the accompanying drawings in which:-

Figure 1 is a front elevational view of a heating apparatus according to one aspect of the present invention;

Figure 2 is a top plan view of the apparatus shown in Figure 1;

Figure 3 is a side elevational view of the apparatus shown in Figure 1;

Figure 4 is a cross-sectional view along line A-A of Figure 1;

Figure 5 is a plan view of a radiator for an apparatus according to another embodiment of the present invention; Figure 6 is a side view of a typical restraint for attaching an apparatus of the present invention to a surface;

Figure 7 and 8 are respectively a side elevational and cross-sectional view of a valve connection for the apparatus shown in Figure 1;

Figure 9 is a front elevational view of a part of an apparatus according to an alternative embodiment of the present invention;

Figure 10 is a plan view of a heating unit for an apparatus according to a further embodiment of the present invention;

Figure 11 is a schematic perspective view of the exterior of a heat transfer unit for an apparatus according to yet a further embodiment of the present invention;

Figure 12 is a schematic perspective view of the heat transfer unit shown in Figure 11 having the casing and manifold removed;

Figure 13 is a schematic perspective view of the heat transfer unit shown in Figure 11 having only the casing removed;

Figures 14a and 14b are respectively a sectional view and a perspective view of an extrusion for supporting heatpipes of a heat transfer system according to yet a

further embodiment of the present invention; and

Figures 15a and 15b are respectively a perspective view and a front plan view of a heat transfer system that incorporates the extrusion shown in Figures 14a and 14b. Referring to Figures 1 to 7 of the accompanying drawings, a heating system 2 according to one embodiment of the present invention is illustrated. The system comprises a radiator unit 4 made of a conducting material, such as aluminum or steel and a main pipe 6. The radiator 4 is in the form of a hollow rectangular block having a front panel 4a, a back panel 4b and side panels 4c. The radiator is relatively narrow in breadth such that, in use, it does not extend too far from the surface (generally a wall) onto which it is mounted. The radiator 4 is an enclosed unit, the interior cavity 12 of which may be partially evacuated by means of a valve 10 provided in one end of the radiator and which also allows the introduction of a small

amount of working fluid into the interior cavity of the vessel. The bottom edge of the radiator 14 is concave in profile and the interior cavity 12 is provided with stiffening tubes 16 at spaced apart intervals to prevent collapse of the unit when the interior cavity is evacuated.

The pipe 6 is a conventional pipe comprised of a heat conducting material through which a heat conducting medium, such as water, is transported. The radiator unit 4 may be placed on to the pipe 6, with the concave bottom edge 14 of the radiator abutting the convex upper surface of the pipe. The radiator unit is secured to the pipe by means of three straps 18 provided at spaced apart intervals along the bottom of the radiator. The radiator is kept in the upright position by the provision of a magnetic restraint 20 attached to the wall 22.

In use, the pipe 6 has a heated medium, such as water or gas, transported through it. For example, water may be heated using a conventional water boiler and then pumped through a network of pipes 6 which are provided throughout a building. The partially evacuated radiator unit 14, having a small amount of working fluid therein, contacts the pipe 6 and heats up, thereby releasing heat to the surroundings by means of radiation, convention and conduction.

The working fluid in the radiator unit 4 is heated by means of the pipe 6 and evaporates below its normal boiling point due to the vacuum which exists inside the unit. The reduced pressure inside the radiator unit also allows the fluid to move rapidly therethrough and, as it does so, condenses to release its latent heat of condensation thereby transferring heat to the walls of the radiator and hence, the

surrounding atmosphere. The fluid is re-circulated to provide a continuous source of heating to the area provided with the heating system of the present invention.

The actual volume of fluid contained within the interior cavity of the radiator will depend upon the particular dimensions of the unit used in the system. Similarly, the amount of vacuum which exists in the unit is important for efficient working of the

system. The amount will depend upon the size of the pipe, the radiator unit and volume of working fluid used in the system and may be obtained by the law of thermodynamics.

Figure 4 of the accompanying drawings illustrates in further detail the stiffening tubes 16 for preventing the collapse of the radiator unit 4. Each tube is formed into a ring and has a slot 30 cut into its bottom which is welded to one interior face of the radiator only. It is to be appreciated that alternative means may be provided to prevent collapse of the cavity under vacuum. For example, Figure 5 illustrates stiffening tubes 31 which resemble an elongated 'T' in plan view which may be

provided at spaced apart intervals along the length of the cavity. Gaps must be provided at both ends of the tubes to allow circulation of the fluid in the radiator. The tubes 31 are shown in the vertical position but may be attached to the surface of the cavity to lie horizontally thereacross.

Figure 4 also illustrates how the radiator 4 is attached to the pipe 6. A strap 18 is attached to the rear panel 4b of the radiator for placing around the pipe 6. A strap strengthening clip 17 is attached in the opposite position on the front panel 4a to enable the strap to be tightened around the pipe, as required. Any number of straps may be provided along the bottom edge of the radiator to secure the pipe thereto.

Figure 6 of the accompanying drawings illustrates in further detail possible fastening means 20 for attachment of the radiator unit 4 to a surface, such as a wall. A magnet 40 is attached to the wall, for example, by means of adhesive and has a steel

tube 42 tapped to suit a stub 44. The screwed stub 44 is welded to the back panel of the radiator unit and extends outwardly therefrom. In this manner, the stub of the radiator can be inserted into the steel tube of the magnet (see Figure 6) to hold the radiator in position. Removal of the radiator, for example, to enable decorating of the

wall behind, is then a simple procedure without the need to unbolt any fixings which are normally required to attach a conventional radiator to a wall.

Figures 7 and 8 show the valve 10 provided in the radiator unit to allow evacuation of the interior cavity. An side panel 4c of the radiator is drilled and a round bar 50 is tapped and welded to the inside of the radiator to allow valve attachment to the tapped block.

It is to be appreciated that the inner walls of the apparatus must be fully protected against corrosive influence due to the presence of the working fluid.

Figure 9 of the accompanying drawings illustrates an alternative apparatus according to the present invention. A main pipe 106 circulates heated water around a building and subsidiary pipes 108 branch off the pipe at intervals and rejoin the pipe further along. A radiator 104 is then sat on the subsidiary pipe 108 as hereinbefore described. A tap 110 allows the flow of water through the subsidiary to be controlled. Heated water may continuously flow around the main pipe but is only able to pass into subsidiary pipe and thereby heat the radiator when the tap is turned to the "open"

position. The heating apparatus of the present invention has a number of advantages over those of the prior art. Firstly, the radiator does not require internal pipework for the flow of water therearound. This reduces the pressure on the pump of the heating system since it no longer has to pump the water around the convoluted pipes of the radiator. The radiator may also be fastened to a heat pipe at any suitable location, thus greatly increasing the flexibility of the location of the radiator. Additionally, the radiator will normally operate at negative pressures up to approximately 100°C depending on the fluid in the radiator. Thus, the radiator will only have to withstand low pressures even at high temperatures. In contrast, the radiators of the prior art always have a positive pressure which increases as the temperature of the medium in the radiator rises. Not only does this result in the radiator of the present invention being safer to use but the radiator may also be made of a lighter and thinner material due to the reduced pressure of the interior of the radiator caused by the partial vacuum. The radiator does not require the large number of valves and taps nor decommissioning of the boiler which are required with the conventional heating systems. A reduced volume of water also has to be heated and transported around the building thereby providing a far more efficient heating system. The heating system of the present invention may also be applied to existing pipework in buildings, thereby enabling the adaptation of old systems to that of the present invention.

The heating system may also be used to provide sub floor heating. Figure 10 of the accompanying drawings illustrates one type of unit that may be rested on the surface of conventional heating pipes that are provided under flooring to assist in heating of the space above. The unit 200 is comprised of multiple sections 200a, 200b, 200c that are welded together. Each section is formed from a T-joint 202 comprising a hollow head part 204 and a hollow leg part 206. The base of the leg part is welded to the leg of another T-joint 208, the head of which has been halved, thereby providing a foot 210 having a curved inner profile. The opening from the

leg in the foot is sealed by suitable means and a valve 218 is provided to allow introduction of the working fluid into the unit and evacuation of the interior. The sections are welded together by the provision of connectors 212 extending laterally from each head of the main T-joints and reducers are provided to ensure that the

fluid drains into the heads rather than collect in the connector. The ends 214 of the units are capped and blanked to ensure that the partial vacuum in the unit is maintained.

In this manner, the unit 200 may rest on the subfloor piping by means of the curved feet 210. The heated medium in the piping is transmitted to the working fluid in the unit resulting in the unit heating up and transmitting heat to the surrounding area. The larger surface area of the unit provides greater heat transfer into the surrounding area than using the smaller conventional heat pipes as the sole source of heat. It is to be appreciated that the units 200 may be any length and size dependent upon the size of the room to be heated and the size of the heat pipes onto

which they are to be placed.

Figures 11 to 13 of the accompanying drawings illustrate yet a further embodiment of the present invention. Each radiator unit 300 is formed from a plurality of heatpipes 302 that are placed in contact with a heating element, such as a hot water pipe 304. Any number of heatpipes may be brought into contact with the heating element. The heatpipes are maintained in place by the provision of a manifold 306 (see Figure 13) having a plurality of channels 308 for receiving the individual heatpipes. A casing 310 (see Figure 11) is then placed over the manifold. The casing is provided with lower airflow holes 312 and upper airflow holes 314 to allow air to enter into the base of the casing and leave through the upper holes. This enables the radiator to not only radiate heat but also release heat to the surroundings by means of convection thereby increasing the efficiency of the heating system. Heating by means of the unit may be further improved by the provision of a fan (not shown) within the casing to assist in circulation of the air. Without the provision of the fan, the rate of heating of the surroundings is dictated by the rate of radiation of heat from the radiator. A thermostat 316 is provided for controlling the temperature of the radiator unit.

The provision of a manifold for receiving a number of heatpipes enables individual faulty heatpipes to be replaced in the radiator unit without having to remove the entire radiator. Additionally, if one of the heatpipes fails to work, the remaining heatpipes will continue to release heat to the surroundings. Previously,

the entire radiator was provided as a single unit whereby if the unit failed, no heat would be released therefrom until the radiator was replaced or repaired. Furthermore, the number of heatpipes that are operational within the radiator unit may be varied by charging or discharging one or more of the heatpipes. For example, if having all the heatpipes charged (i.e. evacuated and containing working fluid) within the unit provided too much heat, some of the heatpipes may be discharged. The system is also cheaper to manufacture. In this respect, altering the size of the radiator unit that is made up of a plurality of upright heatpipes requires only a simple modification to the tooling whereas for a radiator unit comprised of a rectangular block, each size of radiator requires new tooling.

Another advantage of the heating system illustrated in Figures 11 to 13 of the accompanying drawings is that the individual heatpipes may be heated by more than one type of heat source. For example, normally heatpipes are heated by means of a hot water pipe in contact therewith. However, in the system of the present invention if the heat source failed and the water in the pipe could not be heated, for example, due to failure of the boiler, the heatpipes may be heated by means of secondary heat source, such as electricity. For example, an electrical heating element, such as a coil, could be provided at the base of the heat pipes that may be connected to an electrical

power source in a conventional manner, when required.

Furthermore, the system illustrated in Figures 11 to 13 may also be used as a cooling system to remove heat from the surroundings. Instead of cool air entering the casing and warm air being released therefrom, warm air is taken in and the heat absorbed by the heatpipes thereby providing a cooling effect. A fan is preferably

provided to assist in circulation of the air. In this manner, the system may be used as heating and an air-conditioning apparatus depending upon the climate. Previously, separate systems would have had to be installed in a building to provide the required heating and cooling effects.

Figures 14a, 14b, 15a and 15b of the accompanying drawings illustrate an alternative embodiment of the present invention. A longitudinal extrusion 400 is provided around the heating element 402, such as a hot water pipe. The extrusion is provided with an upwardly open bracket 404 along the length thereof for receiving the individual heatpipes 406 thereby maintaining each heatpipe in contact with the heating element. The separate heatpipes are held together to form front and back panels 408 to provide a casing 410. The gap between adjacent heatpipes allows air to enter at the bottom of the casing and be dispelled out the top of the casing. Thus, in this embodiment, the casing is formed integrally with the heatpipes.

Claims

1. A heat transfer (2) system comprising a conduit (6) for transporting a heat transfer medium and an at least partially evacuated self-contained unit (4) in contact with the conduit, the unit having an interior cavity (12) for receiving a fluid whereby heat is transferred to or from the heat transfer medium from or to the fluid in the unit.

2. A heat transfer system as claimed in claim 1, wherein the heat transfer medium is water or gas.

3. A heat transfer system as claimed in claim 1 or claim 2 wherein the unit is a radiator (4).

4. A heat transfer system as claimed in claim 3 wherein the radiator is formed of a single rectangular block (4).

5. A heat transfer system as claimed in claim 3 wherein the radiator (4) is formed of two or more panels.

6. A heat transfer system as claimed in claim 5 wherein the panels are readed.

7. A heat transfer system as claimed in claim 3 wherein the radiator (4) resembles a skirting board.

8. A heat transfer system as claimed in claim 1 or claim 2 wherein the unit is in the form of at least one heatpipe (302).

9. A heat transfer system as claimed in claim 8 wherein a plurality of heat pipes (302) are contained within a manifold (306), the manifold having a plurality of channels (308) for containing the heatpipes.

10. A heat transfer system as claimed in claim 1 or claim 2, wherein the unit is a T-joint (202) comprising a head section (204) and a leg section (206).

11. A heat transfer system as claimed in claim 10 wherein the leg of the T-joint has an inverted semi T-joint (208) attached thereto to provide a foot (210) having a curved inner profile.

12. A heat transfer system as claimed in claim 11 wherein the opening between the main T-joint (202) and the foot (210) is sealed.

13. A heat transfer system as claimed in any one of claims 10 to 12 wherein multiple units (200a, 200b, 200c) are connected together by welding adjacent connectors (212) that extend laterally from the head of each T-joint and the respective ends (214) of the units are capped and

blanked.

14. A heat transfer system as claimed in claim 13 wherein reducers are provided between adjacent heads.

15. A heat transfer system as claimed in any one of claims 1 to 14 wherein the unit (4) is provided with means (10) for introducing a specified amount of the fluid into the cavity (12) and means (10) for partially evacuating the interior of the unit after insertion of the fluid.

16. A heat transfer system as claimed in any one of the preceding claims wherein the lower edge of the unit has a concave profile (14) to abut against the convex profile of the conduit.

17. A heat transfer system as claimed in any one of the preceding claims wherein releasable fastening means (18) are provided for attaching the unit to the conduit.

18. A transfer system as claimed in any one of claims 1 to 10 wherein the unit surrounds the conduit, the unit being a discrete unit to prevent mixing of the contents thereof.

19. A heat transfer system as claimed in any one of claims 1 to 17 wherein releasable fastening means (20) are provided for attaching the unit to a surface (22).

20. A heat transfer system as claimed in claim! 9 wherein a magnetic fastening (20) is provided for attaching to a complimentary fastening provided on the surface.

21. A heat transfer system as claimed in any one of the preceding claims, wherein a casing (310) is provided over the unit, the casing having lower (312) and upper airflow holes (314) to enable the system to transfer heat by means of convention and radiation.

22. A heat transfer system as claimed in claim 21 wherein the casing is formed integrally with the unit.

23. A heat transfer system as claimed in claim 21 or 22, wherein a fan is provided within the casing.

24. A heat transfer system as claimed in any one of the preceding claims wherein the unit is provided with a secondary heat source.

25. A heat transfer system as claimed in claim 24 wherein the secondary heat source is an electrical heating element.

26. A heat transfer system as claimed in any one of the preceding claims wherein the interior cavity of the unit is provided with strengthening elements to prevent collapse thereof under vacuum.