GB2036237A

GB2036237A - Improved thermally-conductive pipe

Info

Publication number: GB2036237A
Application number: GB7904501A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-12-09
Filing date: 1979-02-08
Publication date: 1980-06-25
Also published as: IT7912484A0; GR68479B; LU80854A1; IT1123994B; FR2474677A1; ES241785Y; ES241785U; BE874676A; DE2853233A1; NL7901880A; SE7902113L; PT69196A

Abstract

A pipe is described for embedding in floors, walls and ceilings and through which hot or cool fluids e.g. water, flows to heat or cool a room by conduction and radiation. The pipe (12) is formed from thermally conducting plastics material covered at least in part by a metal foil (14) having a high thermal conductivity to improve heat transfer. The foil may extend completely around the circumference of the pipe or only partially therearound and may be stuck to the pipe by means of an adhesive or may be e.g. high frequency welded thereto; adhesive may be coated or sprayed on the pipe before applying the foil. The foil is pressed or rolled onto the outer surface of the pipe and by applying sufficient pressure the foil can be impressed into the material forming the pipe wall so that the diameter of the pipe is not increased by the application of the foil. The foil typically consists of copper or aluminium or a copper- or aluminium-alloy. A method of applying the foil to the pipe involves laying the foil along the pipe as the latter leaves an extruder (16). Foil may be wrapped around the pipe in a helix with or without welding and/or an adhesive. <IMAGE>

Description

SPECIFICATION Improved heating pipe Field of invention The invention concerns a heating pipe made of a flexible heat-resistant and heat-conducting plastics material.

Background to the invention Heating pipes of this kind are used in heating systems for floors, walls and ceilings.

Hot water flows through them, and in this way they serve to heat rooms. On occasion, and if required, they can be used to cool rooms, or for general air-conditioning, by causing cold water or a coolant to flow through them. They can also be laid in open spaces, in concrete or asphalt. This use could apply to airports, traffic surfaces etc. which have to be kept free of ice. In buildings they are laid on the floor supports and fixed, by means of mountings, spacers, brackets or similar, in the form of loops or bends running up and down etc., and are then covered over with cement flooring or another form of floor covering. They can also be laid between spacers or knobs of mounting plates. These mounting plates, for their part, lie on the floor supports or are fastened to the walls or ceiling of a room. Sheet steel plates may be laid over the spacers or knobs.These cover up the mounting plates with the heating pipes.

The transfer of heat from the heating pipes occurs generally through conduction and, over a very small area, through radiation as well.

The equivalent effect occurs with the use of the heating pipes for cooling purposes. The extent of heat transfer depends primarily on the thermal conductivity of the plastics material which is used for the heating pipes.

The thermal conductivity of plastics materials is limited and reaches only low values. In the case in point, there is the further consideration that the plastics material should be flexible to make it easy to lay, and should be durable and have a good resistance to ageing.

The consequence of this is that the heat transfer by conduction from the heating pipes (within the cement, concrete or other material within which they are embedded), and the transfer of heat into the air space surrounding the heating pipes, does not reach the high levels which are desirable from the point of view of thermo-dynamics.

Object of the invention Arising from the foregoing, the present invention has the objective of producing a heating pipe having improved conduction and radiation heat transfer characteristics then hitherto.

The invention In a heating pipe of the type described a foil made from a metal of high thermal conductivity is applied along the pipe, so as to at least in part enclose it. Due to the close, direct contact between the foil and the plastics material of the heating pipe, there is good heat transfer through conduction. The high specific heat conductivity of the foil, produces better transfer of heat into the foil by conduction and in turn, better transfer of heat into the material which surrounds it such as cement, concrete or similar, than will occur with the conduction of heat directly from the plastics material of the heating pipe into cement, concrete or similar. When heating pipes are laid between the spacers and knobs on mounting plates, they are essentially surrounded by air.Also in this case, the conduction of heat from the foil into the surrounding air, and by radiation to the sheet steel plates lying on the spacers and knobs, is greater than is achieved without using the foil.

The improved heat transfer arising from the use of the foil, as required by the invention, is particularly effective when the temperature of a room is to be increased quickly, or when a room is heated up from scratch. Heat passes from the central heating system of a house relatively quickly, and without any appreciable obstruction, via the floor (and, if embedded in the walls and ceiling, from there as well), into the room(s) which are to be heated.

In general it is sufficient if the foil, according to the invention, is stretched around the circumference of the pipe in an arc of up to 180 . With an arc of 180 , the width of the foil is the same as half the outer circumference of the heating pipe.

If a particularly good heat transfer is desired, the foil can, according to the invention, stretch around the circumference to include an arc of 360 , i.e. over the whole outer circumference of the heating pipe.

There are several possible ways of applying and fixing the foil to the heating pipe. In essence, they are all equally effective. The choice is essentially determined by the production arrangements of the heating pipe manufacturer.

In one method of applying the invention to a pipe, the foil is stuck to the circumference of the pipe.

In another method the foil is welded around the circumference of the pipe.

In a third method the foil is pressed or rolled around the circumference of the pipe.

Preferably the pressing or roiling on the foil takes place immediately after the emergence of the heating pipe from the extruder by which it was made, while the heating pipe is still warm and therefore easily workable.

Welding of the foil onto the heating pipe should also take place while the pipe is still warm. In this way the electrical energy required for the welding process is reduced.

According to a preferred method of apply ing the invention, the foil is pressed into the outer circumference of the heating pipe, so that its outer surface lies flush with the outer circumference of the heating pipe.

Due to their high degree of conductivity suitable materials for the foil are copper, aluminium, or a copper- or aluminium-alloy. Silver, which possesses a particularly high degree of conductivity, is ruled out, in most cases, by reasons of cost. In practice, aluminium or aluminium alloy is used, since these represent a good compromise between heat conductivity and material costs.

The invention will now be described by way of example with reference to the accompanying drawings.

In the drawings Figure 1 is a side view of a section of heating pipe according to the invention, Figure 2 is a perspective view of an embodiment in which the foil covers an arc of 1 80' and is pressed into the outer circumference of the heating pipe, Figure 3 is a perspective view of an embodiment in which the foil covers a complete arc of 360 , Figure 4 is a perspective view, similar to Fig. 2, but in which the foil lies around and over the outer circumference of the heating pipe, Figure 5 is a perspective view of a stage in the process of sticking on the foil, Figure 6 is a simplified perspective view of a process of high-frequency welding-on of the foil, and Figure 7 is a simplified perspective view of a process of rolling on of the foil.

Detailed description of the drawings The drawings show a heating pipe 12 consisting of a plastics material, and a foil 14 which is applied to it. Fig. 1 corresponds to Fig. 2, and Fig. 1 corresponds to Fig. 4. The foil 14 covers an arc of 1 80', or half the outer circumference of the heating pipe 12. In the embodiment of Fig. 2, the foil 14 is pressed into the outer circumference, so that the surface of the foil 14 lies flush with the outer circumference of the heating pipe 12 i.e. the diameter of the covered pipe is substantially the same as that of the uncovered pipe. The foil is applied by welding, rolling or pressing. The foil is pressed into the plastics material as it emerges from the extruder, and is thus still warm and workable.

In the embodiment of Fig. 4, the foil 14 lies on the outer circumference of the heating pipe 12. This is achieved by the use of an adhesive.

One stage in the process of sticking on the foil is shown in Fig. 5. Here the heating pipe 12 is sprayed or coated over half its outer circumference with an adhesive. Next, the foil 14 is rolled on, as shown in Fig. 5.

Fig. 3 on the other hand shows an embodiment in which the heating pipe 12 is completely surrounded by the foil 14.

This embodiment can be produced by any of the described methods.

Fig. 6 shows a heating pipe 12 emerging from the mouthpiece of an extruder 16. A foil strip is unwound from a storage roll 18 and the heating pipe 12 with the foil applied thereto passes into a high frequency welding device shown diagrammatically at 20. Here the foil 14 is heated, and pressed onto and into the outer circumference of the heating pipe 12.

The method shown in Fig. 7 shows the essential elements of the method of Fig. 6.

Here the foil 14 is pressed onto the outer circumference of the heating pipe 12 by a roller 22. In addition, the foil 14 can be heated by high-frequency induction. Equally it, and/or the heating pipe 12, can be coated or sprayed with adhesive in advance of the roller 22.

Although not shown the foil may be wrapped around the pipe in a helix with or without welding and/or an adhesive. The wrapping may to advantage be performed at the exit from an extruder such as that shown at 16.

Claims

1. Heating pipe of flexible thermally conducting plastics material characterised by a foil of metal having a high thermal conductivity, which is applied to the tube so as to at least in part enclose the tube.

2. Heating pipe as claimed in claim 1 characterised in that the foil extends around the circumference of the pipe in an arc of 180 .

3. Heating pipe as claimed in claim 1 characterised in that the foil extends completely around the circumference of the pipe, in an arc of 360 .

4. Heating pipe as claimed in any of claims 1 to 3 characterised in that the foil is held in place by means of an adhesive.

5. Heating pipe as claimed in any of claims 1 to 3 characterised in that the foil is welded onto the pipe.

6. Heating pipe as claimed in any of claims 1 to 3 characterised in that the foil is pressed or rolled onto the outer surface of the pipe.

7. Heating pipe as claimed in any of claims 1 to 3 and 5 and 6 characterised in that the foil is pressed into the outer surface of the heating pipe so that the diameter of the pipe is not increased by the application of the foil.

8. Heating pipe as claimed in any of claims 1 to 7 characterised in that the foil consists of copper or aluminium or, a copperor aluminium-alloy.

9. A method of improving the heat conduction and heat transfer characteristics of a heating pipe substantially as herein described with reference to and as illustrated in the accompanying drawings.

9. Heating pipe constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. A method of forming a heating pipe as claimed in claim 1 substantially as herein described with reference to and as illustrated in the accompanying drawings.

CLAIMS (17 March 1980)

1. A method of improving the heat conduction and heat radiation transfer characteristics of a heating pipe of flexible thermally conducting plastics material, wherein a foil of metal having a high thermal conductivity is applied to the tube so as to at least in part enclose the tube.

2. A method as claimed in claim 1 characterised in that the foil is applied around the circumference of the pipe in an arc of 1 80'.

3. A method as claimed in claim 1 characterised in that the foil is applied completely around the circumference of the pipe, in an arc of 360 .

4. A method as claimed in any of claims 1 to 3 characterised in that the foil is applied by means of an adhesive.

5. A method as claimed in any of claims 1 to 3 characterised in that the foil is welded onto the pipe.

6. A method as claimed in any of claims 1 to 3 characterised in that the foil is pressed or rolled onto the outer surface of the pipe.

7. A method as claimed in any of claims 1 to 3 and 5 and 6 characterised in that the foil is pressed into the outer surface of the heating pipe so that the diameter of the pipe is not increased by the application of the foil.

8. A method as claimed in any of claims 1 to 7 characterised in that the foil consists of copper or aluminium, or a copper- or aluminium-alloy.