Patent Application
20230375284
The invention relates to a profiled part for a heat exchanger, the associated heat exchanger and a method of manufacturing said exchanger. In particular, the invention relates to a heat exchanger able to be of the type made from stainless steel and aluminum or other combinations of two materials for use in an aeronautical or space context.
The heat exchangers used in the aeronautical or space field can be in the form of an enclosure, preferably made of aluminum, surrounding a tube, preferably made of stainless steel, in which a fluid flows, in particular for a transfer of heat from the fluid towards the outside of the enclosure via the tube and the enclosure. The enclosure can be in the form e.g. of plates clasping the tube.
The exchanger is then assembled by welding or soldering the plates forming the enclosure, between which the tube is arranged.
The use of welding or soldering to assemble the exchanger involves a number of disadvantages.
The main disadvantage of assembly by welding is a difficulty of making the production of a number of parts possible on an industrial scale.
The assembly by soldering of elements of two materials of different natures generates differential expansions between the two materials owing to their different coefficients of thermal expansion, which can cause cohesion failure in the heat exchanger owing to the soldering, in particular when a number of parts are required in order to clasp the tube. This can jeopardize the mechanical behavior of the exchanger and specific solutions must be implemented in order to manage these thermal stresses during soldering.
The inventors have thus sought a solution making it possible to facilitate industrial-scale production of heat exchangers comprising a tube surrounded by an enclosure.
The invention aims to provide a profiled part for a heat exchanger, a heat exchanger comprising this profiled part and a method of manufacturing said exchanger.
The invention aims in particular to provide, in at least one embodiment, a profiled part and an exchanger assembled in a way which is simple and can be achieved on an industrial scale.
The invention also aims to provide, in at least one embodiment of the invention, a profiled part and an exchanger which is compatible with a long tube, in particular of a length greater than 3 m.
The invention also aims to provide, in at least one embodiment of the invention, a method of manufacturing the heat exchanger which limits the internal stresses in order to avoid deformations owing to differential expansions during assembly.
In order to do this, the invention relates to a profiled part for a heat exchanger, configured to have at least one fluid flow tube passing through it, comprising, for each flow tube, a hollow cylinder comprising an inner surface configured to receive said flow tube, the cylinder having, in the absence of any mechanical force, a circular cross-section with an inner diameter which is substantially constant over its whole length and substantially equal to the outer diameter of said flow tube, characterized in that the profiled part comprises a slit extending over the whole length of the cylinder and configured to permit, by application of at least one mechanical force to the profiled part, an increase or decrease in the inner diameter of the cylinder in order respectively to permit the insertion of the tube into the cylinder or the clamping of the tube by the inner surface of the cylinder.
A profiled part in accordance with the invention thus makes it possible to receive a tube by threading it in using the presence of the slit for the adjustment of the inner diameter of the profiled part. The inner diameter of the cylinder of the profiled part can be increased in order to permit the tube to be threaded in, or decreased in order to clamp the tube when it is in its final assembly position. The insertion by threading-in consists of aligning an end of the tube with one of the openings formed at each end of the profiled part, in particular at one of the bases of the hollow cylinder of the profiled part, and of inserting by sliding the length of the tube via this opening until the tube is fully inserted into the profiled part.
The profiled part in accordance with the invention is particularly suited for receiving a long tube, e.g. of a length greater than 3 m, the slit making it possible to facilitate assembly even when the inner diameter of the cylinder of the profiled part and the outer diameter of the tube are substantially equal. Without the presence of the slit, the threading-in becomes difficult, even impossible, above a certain length, in particular for a human operator. The profiled part can also receive tubes shorter than, or equal to, 3 m.
According to a first variant of the invention, a weld joint can be applied along the slit at the end of assembly. This weld joint can improve the clamping effect and even the heat exchange between the tube and the profiled part, depending on the material used.
According to a second variant of the invention, soldering can be implemented by prior application of a metallized layer to the tube before insertion into the profiled part, then soldering of the assembled exchanger. The metallized layer is preferably applied by cold spraying, and the final soldering makes it possible to form the solder joint between the tube and the hollow cylinder of the profiled part. The soldering does not cause cohesion failure of the exchanger since clamping is made possible by the profiled part. In this case, the soldering makes it possible to improve the heat exchange between the tube and the profiled part.
The profiled part thus forms the enclosure of the tube in order to form the heat exchanger. In contrast to the prior art method using soldering described above, with a number of parts clasping the tube, the assembly of such a profiled part with the tube in order to create the heat exchange does not necessitate the application of a high level of heat, which would cause cohesion failure between parts forming the exchanger owing to the soldering.
The profiled part is e.g. manufactured by extrusion, and is preferably made of aluminum. The slit is preferably present during manufacture of the profiled part by extrusion but can also be created by machining following manufacture of the profiled part.
In the absence of mechanical force, the inner diameter of the cylinder of the profiled part is substantially equal to the outer diameter of the tube it is intended to receive, i.e. of the order of more or less 5% of the outer diameter of the tube it is intended to receive, in particular can be:
The difference between the outer diameter of the tube and the inner diameter of the cylinder is preferably less than one millimeter, preferably less than some tenths of a millimeter in particular if the tube to be inserted is long (e.g. of a length greater than three meters), preferably even less than some hundredths of a millimeter if the tube to be inserted is short (e.g. of a length less than three meters). In the same way, the increase or the decrease in the inner diameter of the hollow cylinder during application of the mechanical force to the profiled part is minimal, preferably less than one millimeter, preferably less than some tenths of a millimeter in particular if the inserted tube is long (e.g. of a length greater than three meters), preferably even less than some hundredths of a millimeter if the inserted tube is short. The slit thus cannot be opened sufficiently to permit forcing of the placement of the tube by passing through the slit, in particular when the profiled part is made of metal. However, the minimal increase in the inner diameter of the hollow cylinder is sufficient to permit insertion by threading-in by causing the tube to slide via an opening in the hollow cylinder, as stated above.
Advantageously and in accordance with the invention, the profiled part comprises at least two bearing surfaces on either side of the hollow cylinder, which are configured to receive at least one tool permitting application of said at least one mechanical force to the profiled part.
According to this aspect of the invention, the bearing surfaces are adapted to a tool specifically dedicated to the application of the mechanical force or forces applied to the profiled part. The tool may act on the whole length of the profiled part, in particular when the tube to be threaded-in is long.
The invention also relates to a heat exchanger characterized in that it comprises a profiled part in accordance with the invention and at least one fluid flow tube, and configured to permit an exchange of heat between the fluid flowing in the tube and the profiled part.
An exchanger in accordance with the invention thus comprises a profiled part in accordance with the invention, can be assembled without risk of cohesion failure owing to soldering, and can be manufactured for long tubes, in particular longer than 3 m. The contact between the profiled part and the tube is maximized owing to the relaxing of the mechanical forces on the profiled part at the end of the threading-in of the tube. The exchanger obtained is simpler to manufacture and is stronger. Surface treatment of the tube or of the profiled part is possible, in particular prior to assembly of the exchanger or after assembly, e.g. an SAO (sulfuric anodic oxidation) treatment, TCS PACS, physical vapor deposition. PVD, treatment and chemical vapor deposition, CVD, treatment.
Advantageously, the invention relates in particular to a heat exchanger comprising a profiled part and at least one fluid flow tube and configured to make possible an exchange of heat between the fluid flowing in the tube and the profiled part, the profiled part being configured to have each fluid flow tube passing through it, comprising, for each flow tube, a hollow cylinder comprising an inner surface configured to receive said flow tube, the cylinder having, in the absence of any mechanical force, a circular cross-section with an inner diameter which is substantially constant over its whole length and substantially equal to the outer diameter of said flow tube, characterized in that the profiled part comprises a slit extending over the whole length of the cylinder and configured to permit, by application of at least one mechanical force to the profiled part, an increase or decrease in the inner diameter of the cylinder in order respectively to permit the insertion of the tube into the cylinder or the clamping of the tube by the inner surface of the cylinder, and in that the tube is previously covered with a metallized layer before being inserted into the cylinder, said metallized layer being configured for soldering of the tube and of the cylinder when the tube is inserted in the cylinder.
The invention also relates to a method of manufacturing a heat exchanger in accordance with the invention by insertion of at least one fluid flow tube into a profiled part in accordance with the invention, characterized in that it comprises the following steps for each tube:
A method in accordance with the invention can easily be made possible on an industrial scale by the use of a tool suitable for the application of the mechanical force or forces, and preferably the use of a tool for threading the tube into the profiled part. The method is also simpler, less expensive and more reliable.
The tool is in particular adapted to permit the application of the mechanical force over a large part, or even all, of the length of the profiled part in order to facilitate the insertion of the tube by threading it in.
Advantageously and according to a first variant of the invention, the method of manufacture comprises a final step of welding the tube and the profiled part over the length of the slit in the profiled part.
Advantageously and according to a second variant of the invention, the method of manufacture comprises a preliminary step of application of a metallized layer to the tube, and a final step of soldering the heat exchanger so that the metallized layer forms a solder joint between the tube and the hollow cylinder of the profiled part.
The invention also relates to a profiled part, a heat exchanger and a method of manufacture which are characterized in combination by all or some of the features mentioned above or below.
Other aims, features and advantages of the invention will become apparent upon reading the following description given solely in a non-limiting way and which makes reference to the attached figures in which:
In the figures, for the sake of illustration and clarity, scales and proportions have not been strictly respected.
Furthermore, identical, similar or analogous elements are designated by the same reference signs in all the figures.
The profiled part 12 comprises a slit 16 which makes it possible to facilitate the threading-in of the tube 14 during manufacture of the heat exchanger 10.
The profiled part 12 comprises a hollow cylinder 18 making it possible to receive the tube in order to form the heat exchanger.
The tool and its various portions extend over a large part, or even all, of the length of the profiled part in order to permit the mechanical force applied to the profiled part to be rendered uniform.
When the tube is threaded in the profiled part at its intended location, the bearing portion 20 relaxes its mechanical force and the profiled part resumes its resting position, as shown in
The invention is not limited to the embodiments described. In particular, the profiled part can be of different shapes. Furthermore, the inner diameter of the hollow cylinder of the profiled part at rest can be greater than, equal to or less than the outer diameter of the tube, depending on the length of the tube and the difficulty of insertion thereof.
Furthermore, the method of manufacturing the exchanger can provide a preliminary step of application of a metallized layer to the tube before the insertion of the tube into the profiled part and, following the insertion of the tube into the profiled part, a final step of soldering the heat exchanger so that the metallized layer forms a solder joint between the tube and the hollow cylinder of the profiled part. This solder joint makes it possible to improve the heat exchange between the tube and the profiled part without cohesion failure of the exchanger since clamping is made possible directly by the profiled part.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2203063 | Apr 2022 | FR | national |
