FR2841972A1 - Heat exchanger for electrical transformer, comprises two cooling elements, which define through their opposite face circulation channel, and elastically deformable fin is inserted between two opposite faces of cooling element - Google Patents

Abstract

The heat exchanger comprises at least two cooling elements (2) which define through their opposite face (f) a circulation channel (4) for the cooling air. An elastically deformable fin (10) is inserted between the two opposite faces of the cooling element. Independent claims are included for a section for making a fin and a method of making the heat exchanger.

Description

The present invention relates to the technical field of heat exchangers

  heat comprising plates or cooling elements which have

  each at least one face in contact with the air which ensures its cooling.

  In a preferred but not exclusive application, the invention relates to the technical field of radiators for electric transformers comprising a series of parallel tubular elements inside which circulates a fluid to be cooled. Such radiators are generally made of steel and manufactured by mounting the tubular elements on two header tubes with which they

  communicate to define a cooling circuit for the liquid to be cooled.

  The assembly, thus formed, then undergoes an external surface treatment generally comprising shot peening or hot galvanizing and then

  applying a series of coats of corrosion protection coating.

  In fact, the entire external surface of the radiator must be protected in order to prevent the appearance of corrosion points which affect the aesthetic appearance of the

  which can prove to be unacceptable for the life of the device.

  Such radiators generally give satisfaction in their cooling function. However, it has become apparent in use that the thermal performance of these radiators could be optimized by increasing, for example, their surface

  exchange with cooling air.

  However, given the space constraints of the radiators, linked to their implementation, this increase in exchange surface cannot be obtained by an increase in the general size of the tubular elements. In addition, the increase in the area of the radiator in contact with the convection air cannot be achieved by designing a complex radiator structure, since such a structure would be particularly difficult to treat against corrosion. , so that the benefit of increasing the thermal performance of the radiator would be ruined by the impossibility of ensuring perfect protection against corrosion. Thus, there appears to be a need for a new type of heat exchanger which offers both a heat exchange surface, with optimized cooling air and which has a structure adapted to the implementation of '' an effective anti-corrosion treatment by the application in particular of protective coating. In order to achieve this objective, the invention relates to a heat exchanger of the type comprising at least two cooling elements which define by their opposite face, a circulation corridor for cooling air. According to the invention, this exchanger is characterized in that it comprises at least one intermediate fin interposed between the two faces opposite the cooling elements. According to a preferred embodiment, the intermediate fin is compressed between the cooling elements so that it is immobilized at least

by friction.

  However, according to the invention, the intermediate fin could also be glued

  on either or both of the opposite cooling elements.

  The elastically deformable intermediate fin may have any shape suitable for its function. Thus, the intermediate fin can be produced in the form of an elastically deformable cylindrical tube, intended to be inserted in two complementary grooves, each arranged on the opposite faces of the cooling elements. Similarly, the intermediate fin can be produced in the form of a tube having flats intended to come to bear on the flat surfaces of the

cooling elements.

  According to a preferred embodiment, the intermediate fin comprises a core on either side of which extend two longitudinal edges

  elastically deformable bearing on a cooling element.

  According to a characteristic of the invention, the cooling elements have means for receiving the intermediate fin intended to increase the contact surface between the intermediate fin and the cooling elements. The

  reception means can then be produced in any suitable manner.

  According to a characteristic of the invention, the receiving means comprise two facing grooves each arranged in the wall of a cooling element, the intermediate fin then being inserted between, and at least partially, in the two receiving grooves. Preferably, but not strictly necessary, the support flanges of the intermediate fin then have a shape complementary to that of the receiving means in order to promote the thermal conduction phenomena C between the cooling elements and

the intermediate fin.

  According to a preferred characteristic of the invention, the intermediate fin has a cross section in S. According to a preferred form, but not strictly necessary, of embodiment, in order to avoid the appearance of any corrosion at the interface between the and the cooling elements, the surface of the latter, located in contact with the fin

  interlayer, is covered with a protective coating against corrosion.

  In the same direction, when the intermediate fin is made of an oxidizable material such as steel, the surface of the intermediate fin in contact with the cooling elements, is also covered with a protective coating against corrosion. prior to installation. Preferably, the intermediate fin is completely and previously covered with such a coating of

corrosion protection.

  Of course, the intermediate fin could also be made of a corrosion-resistant material such as for example stainless steel, aluminum or a synthetic material having suitable mechanical characteristics and a good coefficient of thermal conduction such as for example , of the

  resin-impregnated carbon fiber.

  According to a characteristic of the invention, in order to increase the heat transfer by thermal conduction between the cooling elements and the intermediate fin, the heat exchanger comprises a thickness of mastic, paste, glue, adhesive or the like, thermally conductor at the support zones of

  the intermediate fin on the cooling elements.

  According to another characteristic of the invention, the heat exchanger comprises at least one and preferably several sets of two intermediate fins which define at least one convection chimney accelerating the

  cooling air speed.

  In a preferred application, the heat exchanger according to the invention is

  intended to cool submerged electrical transformers.

  Thus, according to one embodiment of the invention, the heat exchanger constitutes a radiator for an immersed transformer and the cooling elements are tubular and define channels for the circulation of a fluid.

coolant to be cooled.

  According to another embodiment, the heat exchange takes place with a wave transformer tank, the cooling elements then being formed by the waves of the tank. In this case, the addition of a fin is done between 2 undulations of the tank itself in the same way as it is done between two

elements of a radiators.

  Of course, the heat exchanger according to the invention could be used

for other applications.

  The invention also relates to a profile for the production of an intermediate fin intended to be implemented on a heat exchanger according to the invention. This profile according to the invention then comprises a central core on either side of which extend two longitudinal edges, elastically deformable, of support. According to a characteristic of the invention, the profile has a shape

  symmetrical about the longitudinal axis of the central core.

  According to another characteristic, preferred but not strictly necessary of the invention, the profile has a cross section in S. The profile, according to the invention can be made of any suitable material such as for example steel or aluminum, its surface then being covered with a protective coating against corrosion. The profile can also be made of a composite material resistant to corrosion and having mechanical and thermal conduction characteristics adapted to the function of the intermediate fins. The invention also relates to a method for manufacturing a heat exchanger.

  heat, as previously described.

  According to the invention, this manufacturing process consists, after assembly of the various constituent elements of the exchanger, including in particular the cooling elements, to insert each intermediate fin between two elements of

radiator cooling.

  According to a preferred characteristic of the invention, the insertion of the intermediate fins is carried out after application of a protective coating on the surface

  outside of the radiator and on the outside surface of the fins.

  Preferably but not strictly necessary, the method consists in using intermediate fins which are produced from a profile according to the invention and which have, in cross-section, a width less than the smallest distance separating the facing tubular elements and a length greater than this smallest distance. Each intermediate fin, thus formed, is then freely engaged between two cooling elements so that the length of the intermediate fin is parallel or inclined relative to the tubular elements and the intermediate fin is then pivoted on itself, so to place the length or the major axis of the interlayer perpendicular to the elements

cooling.

  According to a characteristic of the invention, the support flanges of the intermediate fins are, prior to their insertion, coated with a suitable product ensuring good adhesion between the intermediate fins and the cooling elements. Preferably, the coating is ensured by means of an adhesive, a paste or a putty also having good characteristics of

thermal conductivity.

  The invention also relates to a device for inserting at least one fin.

  interlayer for implementing the manufacturing process as described above.

  According to the invention, this insertion device comprises an insertion key comprising: * an elongated body having means for temporarily blocking at least one intermediate fin,

  * at one end of the body, an operating handle.

  The means for temporarily locking the fin on the key can be made in any suitable way, depending on the shape of the fin. Thus, when the intermediate fin is produced from a section of section, the blocking means consist of at least one longitudinal slot intended to receive the core of the intermediate fin. According to a characteristic of the invention, the insertion device also comprises a guide block having at least one bore for receiving and

  guiding in rotation of the end of the wrench opposite the handle.

  According to another characteristic of the invention, the insertion key comprises a guide base which has on the one hand a sliding surface intended to come to bear on the tubular elements during the engagement of the fin between the elements tubular and, on the other hand, a guide surface in frustoconical rotation, intended to be inserted into the complementary bore of the guide block. According to another embodiment, the insertion key is equipped at both

  ends, operating handles.

  Various other characteristics of the invention emerge from the description below made with reference to the accompanying drawings which illustrate different forms

  nonlimiting embodiment of a heat exchanger according to the invention.

  Fig. 1 is a partial and schematic perspective of a heat exchanger

  according to the invention, forming a radiator for submerged electrical transformer.

  Fig. 2 is a partial section along plane II of FIG. 1.

  Fig. 3 is a partial perspective view of a profile constituting a fin

interlayer according to the invention.

  Fig. 4 is an elevation of a key used for the fitting of fins

  spacers on a heat exchanger according to the invention.

  Fig. 5 is a schematic elevation showing a mounting phase of a

  spacer tab on a heat exchanger according to the invention.

  Fig. 6 is a view similar to FIG. 5 of an alternative embodiment of a

  device for inserting the intermediate fins.

  Fig. 7 shows a heat exchanger according to the invention forming part

  integral of a wavy tank for submerged electrical transformer.

  According to one embodiment, more particularly illustrated in FIG. 1, the heat exchanger, according to the invention, generally designated by ref. 1, constitutes a radiator for a submerged electric transformer. The radiator 1 comprises a series of cooling elements 2, each element 2 being hollow or tubular to define a pipe for circulation of a fluid to be cooled. Thus, the tubular elements 2 extend between two flow collectors 3. It should be noted that, according to the illustration in fig. 1, only part of the radiator 1 is shown with three tubular circulation elements, it being understood that the radiator 1 comprises a greater number of tubular elements 2. Similarly, the tubular elements 2 are represented in a substantially horizontal orientation. However, it must be considered that in configuration of use, the tubular elements 2 are arranged in a substantially vertical manner so as to favor phenomena of natural convection, both with regard to the fluid circulating inside the elements that the cooling air circulating in the channels 4 defined by the faces f opposite the elements of

2 successive cooling.

  The manufacture of such a radiator for transformer 1 is generally ensured by first producing the tubular elements 2 and then by assembling the latter on the collectors 3. Once this operation has been carried out, the assembly thus formed is subjected to a treatment. surface by applying an anticorrosion coating such as paint, such a treatment generally involves a shot blasting or galvanizing phase followed by one or more phases of applying paint as is known to those skilled in the art and does not require

  therefore no further explanation.

  A radiator for transformer 1 thus formed, generally gives satisfaction. However, it appeared possible to improve performance by

  increasing the exchange surface with the cooling air.

  To this end, the invention recommends the use of intermediate fins 10 which are arranged in the channels 4 defined by the faces f facing the cooling elements 2. Each intermediate wing is then interposed between the facing faces f, in being in contact with them as shown more

in detail fig. 2.

  According to the example illustrated, the cooling elements 2 have a corrugated surface which defines grooves 11 extending over the entire length of the tubular elements. The grooves 11 are also arranged in correspondence from one tubular element 2 to the other. According to the example illustrated, each intermediate fin is engaged between two successive cooling elements 2 by being placed inside two opposite facing grooves 11. The grooves 11 then provide transverse locking of the fins 10 and promote thermal conduction between the

  elements 2 and the fins 10 by increasing the contact surface between the latter.

  Each intermediate fin 10 is preferably made from a profile 14 which comprises, as illustrated in FIG. 3, a longitudinal core 15, on either side of which extend two support flanges 16 against the elements of

  cooling 2, as will appear later.

  According to the example illustrated, the core 15 has a Z shape and the longitudinal flanges 16 extend from the core 15, so as to give the section 14 constituting each intermediate fin 10, a cross section in S. The profile 14 can be made of any suitable material and preferably but not exclusively from a folded sheet blank. In order to present a satisfactory resistance to corrosion, the profile 14 is preferably covered with a protective coating such as for example a multiplicity of layers of paint. Of course, the profile 14 could also be made of a corrosion-resistant metal such as for example stainless steel, corten steel, aluminum, an aluminum alloy, copper or one of these alloys. Profile 14

  could also be made of a composite material.

  The profile sections 14 constituting the fins 10 are then inserted between the

  faces f opposite the cooling elements 2.

  In order to carry out this insertion, the invention recommends using an insertion device 19 as illustrated in FIG. 4 comprising a key 20 consisting of an elongated body 21 having at least one longitudinal slot 22 and, according to the example illustrated, several longitudinal slots arranged one after the other and each intended to receive the core 15 of a fin 10. In order to allow the positioning of the fins 10 in the body 21, the latter is preferably made up of two longitudinal parts between which the vanes of the fins are pinched. The

  key 20 further comprises, at each of its ends, an operating handle 25.

  The fitting of the fins is carried out by inserting into the channel 4 delimited by two successive cooling elements, the body 21 of the key 20 on which the fins 10 are adapted. To this end, in order to allow this engagement, the fins have in cross section, a width l less than the smallest distance d separating the two successive cooling elements, as shown in FIG. 2. Furthermore, each intermediate fin 10 has a quantity L

greater than the distance d.

  The insertion of the fins is therefore done so that the length L is inclined or parallel to the extension plane of the cooling elements 2. Once this insertion is ensured, the handles 25 being on either side of the radiator 1, the key 20 is turned in the direction of the arrow Fi, so as to forcibly engage the support flanges of the intermediate fins 10 in the grooves opposite the cooling elements 2. It should be noted that during this insertion, the faculty of elastic deformation of the intermediate fin and more particularly of its support edges, is taken advantage of. At the end of rotation, the support edges are then

  engaged in the grooves there opposite the cooling elements 2.

  It should be noted that the support flanges have a shape 1 5 substantially complementary to that of the grooves of the cooling elements 2, in order to provide a large contact surface with the latter and therefore to favor the thermal conduction phenomena between the walls of the elements of

  cooling 2 and the intermediate fin 10.

  According to the invention, the immobilization of the intermediate fin 10 can result from a compression of the latter. However, it is also possible to envisage the use of glue, mastic or the like, having characteristics of good thermal conductivity and ensuring adhesion between the bearing edges of the intermediate fin 10 and the corresponding faces of the elements of cooling 2. Thus, it is possible to use adhesives or sealants having

  good thermal conductivity characteristics.

  According to a preferred embodiment of the invention, the intermediate fins 10 are arranged in pairs so as to define convection chimneys 26 in which the speed of the cooling air is

  accelerated, thereby increasing the heat exchange characteristics of radiator 1.

  The fins 10 of the same pair can then be arranged either head to tail or in opposite directions, as illustrated in A in FIG. 1, either so as to be in the

  same direction as shown in B in this same fig. 1.

  According to the example described above and illustrated in FIGS. 4 and 5, the insertion device 19 comprises a key 24 provided, at each of its ends, with an operating handle 25 intended to be actuated by an operator so that the

  fitting the fins 10 requires the presence of two operators.

  According to another embodiment of the device 19 illustrated in FIG. 6, the key 20 comprises at one end an operating handle 25 and at its opposite end a guide base 30 which has, on the one hand, a sliding surface 31 intended to come to bear on the cooling elements 2 during the engagement of the key 20 and, on the other hand, a rotating guide surface 32 intended to be inserted in a guide block 33 which also has a housing 34 for

  receiving and guiding the surface 32 of the base 30.

  This advantageous arrangement of the invention thus allows the mounting of

  dividing fins 10 by a single operator.

  According to the example described above, the intermediate fins are placed

  works on exchangers constituting radiators for electrical transformers.

  However, according to the invention, the intermediate fins 10 can also be implemented on transformer tanks called wave or wavy. In this case, the tubular elements 2 are formed, as shown schematically in FIG. 7, by folds or waves from the wall 50 of the tank 51 so that the heat exchanger according to the invention is an integral part of the tank 51. The intermediate fins 10 are then interposed between two adjacent tubular elements 2

  as previously described.

he

Claims (19)

  1 - Heat exchanger comprising at least two cooling elements (2) which define by their face (1) opposite, a corridor or channel (4) for circulation of cooling air, characterized in that it comprises at least one intermediate fin (10), elastically deformable, interposed between   the two faces (f) facing the cooling elements (2).   2 - Heat exchanger according to claim 1, characterized in that the fin   interlayer (10) is compressed between the cooling elements.   3 - Heat exchanger according to claim 1 or 2, characterized in that the intermediate fin (10) is bonded to one and / or the other of the elements of cooling (2).   4 - Heat exchanger according to one of claims 1 to 3, characterized in that   that the intermediate fin (10) comprises a core (15) on either side of which extend two longitudinal edges (16), elastically deformable, of support on a tubular element (2).   - Heat exchanger according to one of claims 1 to 4, characterized in   that the cooling elements (2) have means (11) for receiving the intermediate fin (10).   6 - Heat exchanger according to claim 5, characterized in that the receiving means comprise two grooves (11) facing each other, arranged in the wall of a cooling element, the intermediate fin (10) being   inserted between and at least partially in the two receiving grooves (11).   7 - Heat exchanger according to claim 4 and one of   Claims 5 or 6, characterized in that the support flanges (16) of the fin   interlayer (10) have a shape complementary, at least in part, to that   receiving means (11) arranged on the cooling elements (2).   8 - Heat exchanger according to one of claims 4 to 7, characterized in   that the intermediate fin (10) has a cross section in the form of S.   9 - Heat exchanger according to one of claims 1 to 8, characterized in that   that the surface of the cooling elements (2) in contact with the fin   interlayer (10) is covered with an anti-corrosion protective coating.   - Heat exchanger according to one of claims 1 to 9, characterized in   that the surface of the intermediate fin (10) in contact with the elements of   cooling (2) is covered with a corrosion protection coating.   11 - Heat exchanger according to one of claims 1 to 10, characterized in   that it includes a thickness of mastic, paste or the like thermally conductive at the bearing zones of the intermediate fin (10) on the cooling elements (2).   12 - Heat exchanger according to one of claims 1 to 11, characterized in   what it includes at least a set of two intermediate fins (10) which define at least one convection chimney (26) accelerating the air speed cooling.   13 - Heat exchanger according to one of claims 1 to 12, characterized in   that it forms a radiator for cooling an immersed electric transformer, the cooling elements (2) being tubular and defining   circulation channels for a fluid to be cooled.   14 - Heat exchanger according to one of claims 1 to 12, characterized in   that the cooling elements (2) are formed by the folds of the wall   (50) of a corrugated tank (51) for submerged electrical transformer.   - Profile for the production of an intermediate fin (10) constituting a   heat exchanger, according to one of claims 1 to 14, characterized in that it   comprises a central core (15) on either side of which extend two   longitudinal edges (16), elastically deformable, of support.   16 - Profile according to claim 15, characterized in that it has a shape   symmetrical about a longitudinal axis of the central core (15).   17 - Profile according to claim 15 or 16, characterized in that it has a cross section in S.   18 - Profile according to one of claims 15 to 17, characterized in that it is   made of steel and its surface is covered with an anti-corrosion protective coating.   19 - Method of manufacturing a heat exchanger (1) according to one of   Claims 1 to 14, characterized in that it consists of:   - manufacture a series of intermediate fins with dimensions of the intermediate space between two cooling elements, - and, after the assembly of the various constituent elements of the radiator including the tubular elements for the circulation of a fluid to be cooled,   insert each spacer between two cooling elements.   - Manufacturing method according to claim 19, characterized in that it consists in inserting the intermediate fins (10) after application of a protective anti-corrosion coating on the external surface of the exchanger   and on the outer surface of the fins (10).   21 - The manufacturing method according to claim 19 or 20, characterized in that it consists in: - using fins (10) which are produced from a profile   according to one of claims 15 to 18 and which have, in cross section   transverse, a width less (1) than the smallest distance (d), separating the faces (f) opposite the elements (2) and a length (L) greater than this smallest distance (d), - freely engage each spacer blade between two cooling elements (2), so that the length (L) of the spacer blade (10) is parallel to the elements (2) and rotate the spacer blade (10) so as to place the flanges (16) of the fin (10) in   support against the cooling elements (2).   22 - Device for inserting at least one intermediate fin (10) for placing   work of the manufacturing process according to one of claims 19 to 21, characterized   in that it comprises an insertion key (20) which comprises: * An elongated body (21) having at least one longitudinal slot intended to receive the core of the fin, * At at least one end of the body, a handful of maneuver.   23 - Insertion device according to claim 22, characterized in that it comprises a guide block having at least one bore (34) for receiving and guiding in rotation the end of the key opposite the handle and in that the insertion key (20) comprises a guide base (30) which has on the one hand a sliding surface (31) intended to come to bear on the elements (2) during the engagement of the key (20) between the elements (2) and, on the other hand, a guide surface (3) in rotation, intended to be inserted in the complementary bore (34) of the guide block (33).