WO2009060487A1

WO2009060487A1 - Pliable tubular heat exchanger

Info

Publication number: WO2009060487A1
Application number: PCT/IT2008/000673
Authority: WO
Inventors: Gianfranco Bonomi
Original assignee: Five T S.R.L.
Priority date: 2007-11-05
Filing date: 2008-10-30
Publication date: 2009-05-14
Also published as: ITBS20070170A1

Abstract

This invention concerns a tubular heat exchanger, comprising and external tube (11 ) in which extends at least one internal corrugated tube (12) and where the heat exchange takes place between a first fluid flowing in a tube and a second fluid flowing in the other tube. Between the external tube (11 ) and the internal corrugated tube (12) is positioned a filiform element (13) with a helicoidal pitch acting as a spacer between said tubes along all their lengths. The external tube and the internal tube are pliable, and the helicoidal filiform element is wrapped around the internal tube and rests against the internal surface of the external tube to form an annular conduit between said tubes.

Description

"PLIABLE TUBULAR HEAT EXCHANGER"

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Field of the Invention

The present invention concerns high thermal efficiency heat exchangers, in particular one type of heat exchanger comprising an external tube in which at least one corrugated tube extends and where the heat is exchanged between a first fluid flowing in a tube and a second fluid flowing in the other tube. State of the Technique

On the market and at least from the documents US 2007/0187067 and JP 2004/012114, a heat exchanger of the aforesaid type is already known which are made up of two coaxial tubes inserted one in the other and in which fluids flow at different temperatures for an exchange of heat. The tube inside the other is made of a high heat conductivity material that permits an efficient heat exchange between the fluids, whereas the external tube is made of a low heat conductivity material and/or externally insulated to reduce heat dispersion.

The internal tubes in these heat exchangers may be corrugated, that is undulated, to increase in this way the heat exchange surface, as well as the turbulence of the fluids so as to improve the efficiency of the exchanger.

Also known are tubular heat exchangers made up of an external tube and of several parallel internal corrugated tubes. The heat exchangers using corrugated tubes have however drawbacks regarding assembly, in maintaining the internal tubes in the external tube in a coaxial or parallel pitch so that their surfaces do not come into contact and block the passage and consequently the exchange of heat between the fluids in circulation. Furthermore, said exchangers have difficulties if not the impossibility of being bent or shaped depending on their destination and use conditions without becoming flattened and tapered at some points which can alter the regularity of the passage of the fluid.

Object and Summary of the Invention This invention is directed at efficiently resolving the aforementioned problems and at the same time it provide a tubular heat exchanger according to the preamble of claim 1 , wherein between the external tube and at least one corrugated internal tube a solid section or tubular filiform element with helical pattern acting as a spacer between said tubes is provided, and wherein both the external tube and the internal tubes can be made of any material as long as it is bendable.

A heat exchanger according to this invention will have a high bending capacity and at least the following advantages: simplification of the joining between the internal tube or tubes with the external one; guaranteeing of the pitch and coaxiality/parallelism of the tubes along all their length and avoiding flattening, adherence or other deformations; guaranteeing in this way a flow of fluid which is as constant and homogenous as possible for each section; giving different shapes to the exchanger by being able to bend it according to the use conditions. In addition, in the heat exchanger proposed here, the passage of the fluids inside it can be increased and the turbulence augmented with the further advantages of a better heat yield, minimizing the limestone deposits and, therefore, reducing the maintenance work and increasing the lifespan of the system. Brief Description of the Drawings

Greater details of the invention will however become evident from the following indicative and not restrictive description made in reference to the enclosed drawings, in which:

Fig. 1 is an exploded view of the components of a heat exchanger according to a possible example;

Fig. 2 is a longitudinal section of a length of assembled heat exchanger made using the components in Fig.1 ;

Fig. 3 is an end view of the heat exchanger in Fig. 2; Fig. 4 is a longitudinal section of a length of assembled heat exchanger according to a variation in construction;

Figs. 5 and 6 are, respectively, a longitudinal section and a view of an end of a length of a heat exchanger according to a further variation in construction;

Figs. 7 and 8 are, respectively, a longitudinal section and a view of an end of a length of a heat exchanger according to a further variation in construction;

Fig. 9 is a longitudinal section of a heat exchanger according to the invention with an end pipe coupling for a delivery or return of fluids intended to circulate in the tubes for the heat exchange; Fig. 10 in a longitudinal section like that in Fig. 9, but where the external tube is corrugated also; and

Fig. 11 shows a possible heat exchanger with several internal tubes grouped in a bundle. Detailed Description of the Invention

As shown, the heat exchanger 10 proposed is basically made up of an external tube 11 , of at least one internal tube 12 and of at least one filiform spacer element 13.

The external tube 11 can be made of any material, rubber and plastic material included, as long as it can be bent and has low heat conductivity.

Otherwise, it can have an external heat insulating coating 14 to avoid hear dispersion. Its internal diameter is bigger than the external diameter of the internal tube 12. In addition, the external tube 11 can be both single layer and multilayer (Fig, 4). Possibly, the external tube 11 can also be corrugated, that is undulated, as shown in Figs. 7, 8 and 10.

The internal tube 12 has a corrugated wall, that is undulated, and can be made of metal, stainless steel, or any other material as long as it is flexible and has high heat conductivity properties to facilitate the heat exchange between a fluid in circulation in the external tube 11 and a fluid made to circulate in the internal tube 12.

The corrugation/undulation of the internal tube 12 can be parallel as shown in Figs. 1 and 2 or with a helicoidal pitch, even with several starts, as shown in Figs. 4, 5 and 7. The filiform spacer element 13 can be solid section or tubular and made of any metal material, stainless steel included, rubber or plastic, preferably having low heat conductivity. Nonetheless, it is provided with a helicoidal pitch and wrapped around the internal tube 12 along all its length. This is so that it will be between the internal 11 and external tube 12 to maintain the coaxiality/parallelism between the two tubes and so as to form between them an annular channel 15 also helicoidal and with a constant section even when the assembly is bent differently.

When the internal tube 12 has a helicoidal corrugation/undulation, the filiform spacer element 13 can be wrapped around the internal tube, both with the same helicoidal pitch of the corrugation/undulation as in Figs. 4 and

7, and with the contrary pitch as in Fig.5. In the first case, the filiform spacer element 13 can find trim in a helicoidal loop 12'of the corrugated external surface of the internal tube 12, a loop which can in this case be specifically sized at least in depth.

Assembly of the heat exchanger is carried out, for example, by wrapping the helicoidal spacer element 13 as a precautionary measure around the internal tube 12 and then introducing these combined components into the external tube 11. The external tube 11 will then be connected to a system provided for the circulation of a first fluid in the annular channel 15, whereas the internal tube 12 will be connected to a system for the circulation of a second fluid for heat exchange, preferably against the current, with the first fluid flowing in said annular channel. Such a connection can be carried out, for example, by means of a pipe fitting 16 made specially for the fluid to flow through channel 15 according to the arrows F and into the internal tube 12 according to the arrow G, -Figs 9, 10- where, furthermore, it can be seen that around the end of the internal tube 12 connected to the pipe fitting 16, a seal 17 and an anti-slip ring 18, the latter preferably in two halves, is provided. In Fig. 9 the external tube has a smooth outside surface, whereas in Fig. 10 the external tube has a corrugated wall and also provided with sealing means 19.

The filiform element 13 acts however as a guide and support for the internal tube 12 in the external tube 11 , ensuring their coaxiality without preventing the possibility that the whole can be bent and shaped according to necessities and depending on the destination and position of the exchanger at the moment it is used. Furthermore, on the one hand, the corrugation of the internal tube 12 helps to confer the fluid flowing in the tube with a turbulent movement, and on the other, the filiform element 13, together with the corrugation of the internal tube and also possibly of the external tube 11 , forces the flow of the fluid in the annular channel 15 to follow an uneven, basically helicoidal path which increases the turbulence optimizing the heat exchange between the two fluids and reducing the limestone deposits as required. Lastly, it should be noted that always in accordance with the invention and with the intention of achieving the same aim and results, a tubular and pliable heat exchanger 20 can be made up of an external tube 21 , corrugated or not and insulated towards the outside, and of several internal corrugated tubes 22 bunched together by means of a peripheral helicoidal filiform element 23 acting as a spacer between them and the internal surface of the external tube and possibly distanced one from the other by means of other helicoidal filiform elements 23' wrapped around each internal tube as shown in Fig.10.

Claims

"PLIABLE TUBULAR HEAT EXCHANGER" * * * * C L A I M S

1. A tubular heat exchanger, comprising and external tube (11) in which extends at least one internal corrugated tube (12) and where the heat exchange takes place between a first fluid flowing in a tube and a second fluid flowing in the other tube, characterized by the fact that between the external tube (11 ) and at least one internal corrugated tube (12) is positioned a filiform element (13) with a helicoidal pitch acting as a spacer between said tubes along all their lengths, and in the fact that both the external and internal tube or tubes are pliable.

2. A heat exchanger according to claim 1 , in which said helicoidal filiform element (13) has either a solid or tubular section and can be made of metal, rubber or plastic.

3. A heat exchanger according to claims 1 or 2 in which the internal tube (12) has parallel corrugation and the helicoidal filiform element (13) is wrapped around said internal tube and rests against the internal surface of the external tube to form an annular conduit (15) between the two tubes

4. A heat exchanger according to claims 1 or 2 in which the internal tube (12) has helicoidal corrugation, at one or more principles and the helicoidal filiform element (13) is wrapped around said internal tube and rests against the internal surface of the external tube to form an annular conduit (15) between the two tubes.

5. A heat exchanger according to claim 4, in which the helicoidal filiform element (13) is wrapped around the internal tube (12) with the same helicoidal pitch as its external corrugation.

6. A heat exchanger according to claim 5, in which said helicoidal filiform element (13) fits into a helicoidal loop of the external corrugation.

7. A heat exchanger according to claim 4, in which the helicoidal filiform element (13) is wrapped around the internal tube (12) with a helicoidal pitch contrary to its external corrugation.

8. A heat exchanger according to any one of the previous claims, in which the external tube (11) is made of a low heat conductivity material and/or is heat insulated towards the outside, and the internal tube (12) is made of a high conductivity material.

9. A heat exchanger according to any one of the previous claims, provided with means for a contribution of a first fluid in the conduit between the external and internal tubes and a second fluid in said internal tube.

10. A heat exchanger according to claim 9, in which at least one end both of the external tube and the internal tube is fixed to a pipe fitting with the interposition of a seal and an anti-slip means.