GB1602719A

GB1602719A - Sealing constructions for finned heat pipes

Info

Publication number: GB1602719A
Application number: GB1559677A
Authority: GB
Original assignee: Curwen & Newberry Ltd
Current assignee: Curwen & Newberry Ltd
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1981-11-18

Description

(54) IMPROVEMENTS RELATING TO SEALING CONSTRUCTIONS FOR FINNED HEAT PIPES (71) We. GURWEN & NEWBERY LIMITED, a British Company of Westcroft Works, Alfred Street, Westbury, Wiltshire BA13 3DZ, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a sealing construction for a finned heat pipe. For the purposes of this invention a heat pipe is defined as a closed tube containing a substance whose vapour pressure and evaporation points are so related to the temperature and pressure conditions within the tube that the substance will evaporate at a relatively warm end of the tube and will condense at the other cooler end and the condensed liquid will flow back from the cool end to the warm end where the cycle restarts.Such a heat pipe acts as a useful conductor of heat between the two zones.

To assist in the heat transfer between the tube and any surrounding fluid (liquid or gas) it is desirable to provide the tube with external heat exchange fins. Since the contacting fluid will commonly flow across the length of the tube.

these fins are preferably transverse. i.e. they lie in planes substantially perpendicular to the length of the tube. The term transverse fins" is also intended, however. to include a single or multiple fin which is wound in the form of a spiral around the tube.

In many applications such a finned tube has to be mounted in a supporting plate or wall, or alternatively it may be required that the finned tube should be sealed in an aperture in a wall to prevent external fluid passing through the opening. This applies for example to a rotary regenerator or heat exchanger in which finned heat pipes have their opposite ends exposed within two different fluid ducts and it is required that an intermediate point of the tube should be sealed in a dividing wall.

According to the present invention there is provided a sealing construction for a finned heat pipe, comprising a heat pipe provided with external transverse fins (as hereinbefore defined) along part or whole of the length of the pipe, a wall having an aperture substantially the same shape and dimensions as the fins, through which aperture the pipe extends, and a sealing substance or body connecting at least two adjacent fins in the region of the wall and disposed between them so as to form a seal or part of a seal between the heat pipe and the wall.

Preferably the sealing substance is plastic or mouldable, for example a mouldable plastics material or putty, or an elastomeric material.

Alternatively the sealing body may be a rigid metal body such as a machined ring or a body of weld metal.

In a particular preferred construction the sealing substance or body connects three or more adjacent fins. Conveniently also there is a surrounding tube in close contact with the edges of one or more of the tube fins, the tube being secured to the apertured wall. The tube may span lengthwise over at least three gaps between adjacent fins, and the wall may have a large number of apertures in which are mounted a plurality of separate finned heat pipes.

The invention may be performed in various ways and a number of embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation illustrating a finned heat pipe located in an aperture in a partition wall with a sealing substance introduced between adjacent fins, Figure 2 is a diagrammatic side elevation of part of a finned heat pipe in the region of the partition wall, the wall incorporating a rigid guide tube, Figure 3 is a plan view of a support wall or plate for supporting a plurality of finned tubes, Figure 4 is a vertical section along the line III III of Figure 3, showing an insulated wall, Figure 5 is another vertical section of an insulated wall illustrating an alternative construction with guide tubes pressed out of the wall, Figure 6 is another vertical section of an insulated wall illustrating a construction with tube guides moulded integral with the wall, and Figure 7 is a similar view to Figure 2, showing a machined ring sealing body with an insulated layer.

Referring first to Figure 1, a heat pipe 10 is a metal tube formed of a thermally conductive metal, such as copper or aluminium, closed at both ends and containing a suitable substance such as Freon (Registered Trade Mark) at a selected pressure such that the Freon will evaporate at the warm end of the tube and will condense at the cool end. The tube may also include an internal wick or coating, as described in Patent Specification No. 1425472 and may be fitted with a vibrator, as described in Application No. 50930/75 (Serial No. 1566709). In this particular application the tube forms part of a thermal regenerator with the opposite ends of each tube located respectively in two fluid streams where the gases flow in counter current at different temperatures in the direction shown by the arrows in Figure 1.The fluid streams flow through adjacent pipes 20 which have a common dividing wall or plate 11.

The heat pipe 10 has a large number of parallel transverse circular fins 12 formed integral with its outer wall. These fins may be of square or other shape as seen end on, but are essentially uniform and.may be formed by a continuous spiral fin "wound" around the tube. The dividing plate 11 has an aperture 13 of substantially the same size and shape as the fins 12 and in the region where the finned tube passes through the plate a sealing substance 14 is introduced into the gaps between two or three adjacent fins, as illustrated in Figure 1. This substance may, for example, be a synthetic plastics or putty or a rubbery compound. It may be of advantage that this should be a thermal insulating material to prevent heat conduction into the dividing plate 11.Since the sealing substance occupies an appreciable length, it is possible tok form an effective seal without the need to anchor the tube lengthwise with great accuracy. Likewise, if the fin is of spiral shape the sealing substance prevents leakage of gas around the spiral. If required a further plastic or mastic sealing substance may be introduced into the narrow gap between the main body 14 and the edge of the opening 13. This latter sealing material may be more temporary in nature so that it can be more readily removed and replaced.

Referring to Figure 7 of the drawings, a rigid metal body 21 may be cast of the required size and fitted permanently in position. In order to reduce heat transference between the body 21 and the plate 11, a jacket 22 of insulating material is placed around the body 21 between the plate and the body.

Figure 2 illustrates a possible alternative in which a guide tube 16 is fitted in the opening in the divider plate 11. This guide tube preferably spans over the gaps between at least three or four fins 12 and may be permanently and rigidly attached to the plate 11. As in the embodiment of Figure 1 a more temporary sealing material may be introduced into the narrow gap between this guide tube 16 and the sealing substance 14.

In practice, a plurality of finned heat pipes 10 may be assembled in corresponding apertures in a common divider plate 11, and a suitable plate 11 for this purpose is shown in Figure 3.

It may often be advantageous to provide an insulated wall and Figure 4 illustrates two parallel plates 11 having insulating wall material 23 therebetween.

Figure 5 illustrates how guide tubes 18, similar in function to the tube 16 of Figure 2, can be formed in plate 11 by punching or pressing out from the plane of the plate.

In Figure 6, guide tubes 19 are formed integral with the divider walls 11 as a unitary moulding in glass fibre reinforced synthetic plastics. Guide tubes 18 and 19 can ofcoursebeemployedwitha single dividing wall 11 without insulation material 23.

WHAT WE CLAIM IS:- 1. A sealing construction for a finned heat pipe, comprising a heat pipe provided with external transverse fins (as hereinbefore defined) along part or whole of the length of the pipe, a wall having an aperture substantially the same shape and dimensions as the fins, through which aperture the pipe extends, and a sealing substance or body connecting at least two adjacent fins in the region of the wall and disposed between them so as to form a seal or part of a seal between the heat pipe and the wall.

2. A sealing construction according to claim 1, wherein the sealing substance is a mouldable plastics material or putty or an elastomeric material.

3. A sealing construction according to claim 1, wherein the sealing body is a rigid metal body.

4. A sealing construction according to claim 3, wherein the metal body is a machined ring or a body of weld metal.

5. A sealing construction according to claim 3 or 4. wherein heat insulating material is located between the outer surface of the sealing body and the wall.

6. A sealing construction according to any one of claims 1 to 5, wherein the sealing substance or body connects three or more adjacent fins.

7. A sealing construction according to any one of claims 1 to 6, including a surrounding tube in close contact with the edges of one or more of the fins, the tube being secured to the apertured wall.

8. A sealing construction according to claim 7, wherein the tube spans at least three gaps between adjacent fins.

9. A sealing construction according to any one of the claims 1 to 8, wherein the wall has a plurality of apertures, in each of which is mounted a transverse finned heat pipe.

10. A sealing construction for finned heat pipes substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. metal tube formed of a thermally conductive metal, such as copper or aluminium, closed at both ends and containing a suitable substance such as Freon (Registered Trade Mark) at a selected pressure such that the Freon will evaporate at the warm end of the tube and will condense at the cool end. The tube may also include an internal wick or coating, as described in Patent Specification No. 1425472 and may be fitted with a vibrator, as described in Application No. 50930/75 (Serial No. 1566709). In this particular application the tube forms part of a thermal regenerator with the opposite ends of each tube located respectively in two fluid streams where the gases flow in counter current at different temperatures in the direction shown by the arrows in Figure 1.The fluid streams flow through adjacent pipes 20 which have a common dividing wall or plate 11. The heat pipe 10 has a large number of parallel transverse circular fins 12 formed integral with its outer wall. These fins may be of square or other shape as seen end on, but are essentially uniform and.may be formed by a continuous spiral fin "wound" around the tube. The dividing plate 11 has an aperture 13 of substantially the same size and shape as the fins 12 and in the region where the finned tube passes through the plate a sealing substance 14 is introduced into the gaps between two or three adjacent fins, as illustrated in Figure 1. This substance may, for example, be a synthetic plastics or putty or a rubbery compound. It may be of advantage that this should be a thermal insulating material to prevent heat conduction into the dividing plate 11.Since the sealing substance occupies an appreciable length, it is possible tok form an effective seal without the need to anchor the tube lengthwise with great accuracy. Likewise, if the fin is of spiral shape the sealing substance prevents leakage of gas around the spiral. If required a further plastic or mastic sealing substance may be introduced into the narrow gap between the main body 14 and the edge of the opening 13. This latter sealing material may be more temporary in nature so that it can be more readily removed and replaced. Referring to Figure 7 of the drawings, a rigid metal body 21 may be cast of the required size and fitted permanently in position. In order to reduce heat transference between the body 21 and the plate 11, a jacket 22 of insulating material is placed around the body 21 between the plate and the body. Figure 2 illustrates a possible alternative in which a guide tube 16 is fitted in the opening in the divider plate 11. This guide tube preferably spans over the gaps between at least three or four fins 12 and may be permanently and rigidly attached to the plate 11. As in the embodiment of Figure 1 a more temporary sealing material may be introduced into the narrow gap between this guide tube 16 and the sealing substance 14. In practice, a plurality of finned heat pipes 10 may be assembled in corresponding apertures in a common divider plate 11, and a suitable plate 11 for this purpose is shown in Figure 3. It may often be advantageous to provide an insulated wall and Figure 4 illustrates two parallel plates 11 having insulating wall material 23 therebetween. Figure 5 illustrates how guide tubes 18, similar in function to the tube 16 of Figure 2, can be formed in plate 11 by punching or pressing out from the plane of the plate. In Figure 6, guide tubes 19 are formed integral with the divider walls 11 as a unitary moulding in glass fibre reinforced synthetic plastics. Guide tubes 18 and 19 can ofcoursebeemployedwitha single dividing wall 11 without insulation material 23. WHAT WE CLAIM IS:-

1. A sealing construction for a finned heat pipe, comprising a heat pipe provided with external transverse fins (as hereinbefore defined) along part or whole of the length of the pipe, a wall having an aperture substantially the same shape and dimensions as the fins, through which aperture the pipe extends, and a sealing substance or body connecting at least two adjacent fins in the region of the wall and disposed between them so as to form a seal or part of a seal between the heat pipe and the wall.