SE457476B - PROCEDURE FOR MANUFACTURE OF HEAT EXCHANGE IN WHICH ONE MEDIUM IS GUIDED IN UN-FORMED CHANNELS - Google Patents

Abstract

A heat exchanger is operated by a first medium and a second medium and comprises a tank (8) having an inlet chamber (9) and an outlet chamber (10) and containing said first medium, as well as a heat transfer pile (2) with tubes (3) for circulating said first medium, said tubes (3) having a U channel with an inlet (5) for connection to said inlet chamber (9) and an outlet (6) for connection to said outlet chamber (10), said heat transfer pile having fin units (4) arranged alternately with said tubes (3) and adapted to guide said second medium past said tubes. Each tube is formed by bending a strip and joining together its longitudinal edges; the bent strip is flattened and cut into tube blanks; the cut tube blanks are closed at the one end portion; and a partition is provided in the longitudinal direction of each tube blank to form said tube, the inner end of said partition being provided at a distance from the closed end portion of the tube blank to form the said U channel.

Description

457 476 2 something which is disadvantageous in view of the movement of the glue and thus the sealing of the pipes against the tank.

According to the invention, a heat transfer package is provided with flat pipes, which in their longitudinal direction have a partition wall, which extends to a place at a distance from the bottom of the pipe to form a flat U-channel formed for inflow and outflow, respectively. The advantage of the flat pipes is, as mentioned above, that a larger heat transfer surface is obtained at the same time as the size of the heat exchanger is reduced for a given heat transfer capacity, which is not least important today in view of the use of such heat exchangers as coolers. or heaters in vehicles. The object of the invention is to provide a heat exchanger with a higher temperature efficiency per m2 of heat exchanger and to provide a heat exchanger which has a lower weight, smaller dimensions and thereby smaller installation dimensions. Furthermore, it is an object to eliminate in a new and ingenious manner the diverting tank used on heat exchangers according to the prior art, at the same time as a more even temperature distribution in the heat transfer package is obtained through the U-flow of the flow stream.

These objects are achieved by a method of initially mentioned slag which is characterized in that each tube is formed by bending and joining a strip in the longitudinal direction, that the bent strip is flattened and cut into tubes, that the cut tubes are closed at one end portion, and that a partition wall is provided in the longitudinal direction of each pipe blank for forming said pipe, the inner end of the partition wall being arranged at a distance from the closed end portion of the pipe blank for forming said U-channel.

The invention will be described in more detail below with reference to a number of accompanying drawing figures provided with reference numerals, which show a preferred exemplary embodiment. 457 476 3 Fig. 1 shows in perspective and with certain parts broken away a heat exchanger manufactured according to the invention.

Fig. 2 shows a tube included in the heat exchanger in perspective.

Fig. 3 shows a section along the line III-III in Fig. 2.

Fig. 4 shows from above a tank with sockets for connection to the pipes.

Fig. 5 shows from above a perforated strip, which is included in the lamella assembly of the heat exchanger.

Fig. 6 shows a section along the line VI-VI in Fig. 5.

Fig. 1 shows a heat exchanger 1 manufactured according to the invention with a heat transfer package 2, which comprises several pipes 3 for circulating a first medium, for example water, and several lamella assemblies 4 arranged alternately with the pipes 3, past which a second medium, eg air, is intended to flow. The heat exchanger 1 according to the described example can function both as a heater and a cooler. The lamella assembly 4 consists of a perforated and pleated band, which will be described later. each pipe 3 has at its one end an inlet 5 and an outlet 6 and is closed at the other end. Each tube 3 has a partition wall in the form of a rod 7, which is inserted into the tube 3 and whose inner end is located at a distance from the closed end of the tube 3. Thereby a U-channel is formed for circulation of the first medium. The water thus flows in through the inlet 5, through the U-channel and out through the outlet 6. A tank 8 with an inlet chamber 9 and and an outlet chamber 10 is connected to the open ends of the pipes 3. The inlet 5 of the pipes 3 is thus connected to the inlet chamber 9, while the outlet 6 of the pipes 3 is in communication with the outlet chamber 10. The water flows into the inlet chamber 9 of the tank 8 via an inlet nozzle 11 and then flows through the inlet of the pipes 3. ducts and out into the outlet chamber 10 of the tank 8, from which the water finally flows out via a schematically shown outlet socket 12 located in the upper part of the tank 8. In the example shown, the second medium is constituted by air. , which flows through the lamella bearing assembly 4 in the direction of the arrow A. This air flow cools the first medium (water) flowing through the 3 U-channels of the pipes. The special, flattened shape of the pipes 3 provides a large heat transfer surface, which in addition to the water's U-flow further promotes cooling. Finally, the heat exchanger 1 has upper and lower plates 13, which stiffen the heat transfer package 2. The rear end 14 of the heat exchanger 1 consists of pipe end portions 15, which are bent about 90 ° when the pipes 3 are closed. The front end is formed by the tank 8.

Fig. 2 shows the design of a tube 3. The tube 3, which preferably consists of aluminum, has a U-channel with inlet 5 and outlet 6. The U-channel is provided by the end of the tube 3 being closed by bending the end portion 15 about 90 ° and that the rod 7 is inserted as a partition in the tube 3. The outer end portion 16 of the rod 7 projects outside the open end of the tube 3, i.e. past the inlet 5 and the outlet 6, while its inner end 17 is located at a distance from the closed end 15 of the tube 3. 3 is collared at the inlet 5 and the outlet 6, respectively, in order to provide a larger inlet and outlet area at the connection to the sockets described later. The collar also serves to reduce the throttling that occurs at the connection between the pipes and the sockets. Furthermore, the outside of the tube 3 has depressions 18 which provide discontinuities within the tube 3. These discontinuities provide turbulent flow in the first medium and serve as a guide for the rod 7.

Fig. 3 shows a section through the tube 3, the flattened shape of which is clearly visible. The space of the pipe 3 to the right of the rod 7 is the inlet side of the U-channel, while its outlet side consists of the left part. The depressions 18 provided in the top and bottom of the tube 3 form internal axes 19 for producing turbulent flow. The ridges 19 are preferably slightly inclined and together with the rod 7 form an arrowhead pattern (see Fig. 2). According to an alternative embodiment, the partition wall, which here consists of the rod 7, can instead be achieved by pressing in longitudinal axes from the flat sides of the tube 3, which are tightly compressed. The axis portion thus pressed in has then preferably the same extent in the tube 3 as the rod 7 (see Fig. 2).

Fig. 4 shows the part of the tank 8 which is to be connected to the inlet 5 and outlet 6 of the pipes 3. 8 at the bottom 22 a recess 23 is accommodated between adjacent sockets 20, 21 for receiving the end portion 16 projecting from the tube 3. A ditch 24 accommodated in the bottom 22 surrounds each socket 20, while a similar ditch 25 surrounds each socket 21 Each ditch 24, 25 has glue channels 26 for a purpose described below.

Each pair of sockets 20, 21 is surrounded by a wall 27 projecting from the bottom 22, which is considerably thicker than the sockets 20, 21. When connecting the tank 8, which preferably consists of some plastic material, to those in the heat transfer package 2 the inlet 5 and outlet 6 of the input pipes 3, respectively.

Then the tank 8 is pressed on the open, collared tubes 3 of the tubes 3, an adhesive, for example glue, is first introduced into the ditches 24, whereby excess glue flows out into the glue channels 26 to ensure a good connection. The projecting end portion 16 (see Fig. 2) of the rod 7 is received in the recess 23, which is preferably also filled with glue, which further stabilizes the connection.

Fig. 5 shows a strip 28, preferably consisting of aluminum, which after folding forms a lamella assembly 4 for the heat transfer package 2. The strip 28 is provided with perforations in the form of first slits 29 and second slits 30. The slits 29, 30 are punched out of the belt 28 and widened by bending. The first slits 29 are so occupied that their openings face the openings of the second slits 30, as best seen in Fig. 6. In the manufacture of the lamella assembly 4, the belt 28 provided with slits 29, 30 is folded. The lamella assemblies 4 are placed 457 457 476 6 then alternately between the tubes 3 in the heat transfer package 2 of the heat exchanger 1. When the second medium (air) flows past the lamella assemblies 4, the opposite slots 29, 30 cause a distribution and splitting of this flow in the heat transfer package 2 and have to purpose of breaking a laminar boundary layer, which on a flat surface would lay as an insulation. The distributed, fragmented and preferably turbulent flow past the lamella assemblies 4 promotes the heat transfer between the pipes 3 and the lamella assemblies 4.

The heat exchanger 1 operates in short in the following way. Dot water to be cooled flows into the tank 8 via the inlet nozzle 11 and further through the 3 U channels of the pipes and out via the outlet nozzle 12 of the tank 8. 2, this air flow also thanks to the above-described slots 29, 30 being distributed in the entire package 2 to ensure good heat transfer. The ridges 19 arranged in the tubes 3 promote turbulent flow in the water flowing through the 3 U-channels of the tubes, which further improves the heat transfer.

The manufacture of the heat exchanger 1 according to the preferred embodiment can, for example, take place in the following manner.

First, a strip blank is bent into a tubular shape and joined together by welding or folding in its longitudinal direction. Before welding or folding, discontinuities are created on the belt, which after bending the belt are located on the inside thereof. The bent strip is then plated by passing it through a solder bath before welding or folding. The bent strip is then flattened and cut into pipe blanks, which are closed at one end portion by squeezing. Thereafter, a partition wall is provided in the lumbar direction of each pipe blank, the inner end of the partition wall being arranged at a distance from the closed end portion of the pipe blank to form a U-channel intended for flow. Thereafter, the closed end portions of the pipe blanks are bent at an angle of about 90 °, which ends the manufacture of the pipes 3.

Along another shorter production line, the lamella assemblies 4 are manufactured, the starting material of which, like the tubes 3, consists of a strip 28, which is punched to form slits 29, 30, which extend in the longitudinal direction of the strip 28 and form rows of transverse running in the strip 28. first and second wear areas. The slots 29 and 30, respectively, are bent out of the band 28 (ie out of the plane of the drawing in Fig. 5) in such a way that the openings of the slots are opposite. Thereafter, the slotted band 28 is now folded alternately in one and the other direction along fold lines B and C to form an endless, folded lamella band. The length of the slots 29, 20 is preferably slightly smaller than the width of the lamella assembly 4 between the tubes 3. The lamella band is cut into lengths which are slightly smaller than the length of the tubes 3.

The tubes 3 and the lamella assembly 4 formed by cutting the endless lamella band are now packed alternately in a fixture intended for the purpose and tightened together with a specific torque. In this case, the ends of the tubes 3 folded about 90 ° are so long that they overlap each other in the heat transfer package 2 formed by the gasket, so that they form one end of the package 2. In the case of the tubes and the lamella assemblies, two pieces of the heat transfer package 2 can be plated plates are also applied, preferably of aluminum, to stiffen the complete heat transfer package 2. The heat transfer package thus formed with its fixture is now inserted into a purpose-built soldering furnace in which the temperature is gradually increased and in which vacuum is gradually created. said that the plating previously applied to the pipes 3 and the plates 13 melts and by capillary forces creeps into the narrow pockets between the plates and the lamella assemblies and the pipes and the lamella assemblies and the pipes and their partitions and solder together 10 15 20 457 476 8 these, no oxidation taking place due to the vacuum prevailing in the furnace. The heat transfer package 2 is then taken out of the oven and allowed to cool. The open ends of the pipe 3 are collared to be given a shape corresponding to the connection sockets arranged in the tank. Then each pipe included in the heat transfer package is pressure tested. After approval, this is placed in an aging oven for the package to undergo a curing process.

Finally, the intention is that the heat transfer package 2 should be joined to an injection molded tank intended for the open pipe ends, preferably in plastic. In this case, glue is applied in the glue ditch 24, 25 arranged on the tank towards the open pipe ends at the sockets 20, 21 and the heat transfer package is inserted into their respective glue ditches, the outer end portion 16 of the rod 7 being inserted into recesses 23 and superfluously arranged in the glue ditches. glue is pressed out through glue channels arranged on the outer walls of the glue ditches and whereby the open ends of the pipes 3 can be inserted into the ditches without further collar. The adhesive is then allowed to cure, after which a ready-made heat transfer package with tank is available.

Claims (10)

10 15 20 25 30 457 476 PATENT CLAIMS A method of manufacturing a heat exchanger (1), which operates with a first and a second medium and which comprises a tank (8) provided with inlet and outlet chambers (9 and 10, respectively) for the first medium, a heat transfer package ( 2), which has pipes (3) for circulating the first medium, which pipes (3) have a U-channel with inlet (5) for connection to the inlet chamber (9) and outlet (16) for connection to the outlet chamber (10), and which has lamella assemblies (4) arranged alternately with the tubes (3) for guiding the second medium past the tubes (3), characterized in that each tube (3) is formed by bending a strip and joined in the longitudinal direction, that the bent strip is flattened and cut into pipe blanks, that the cut pipe blanks are closed at their one end portion, and that a partition is provided in the longitudinal direction of each pipe blank to form said pipe, the inner end of the partition being arranged on distance from the closed end portion of the pipe blank for forming boards and U-channel. 2. A method according to claim 1, characterized in that the partition wall is provided by inserting an elongate element (7) into the pipe blank in order to seal in a sealing manner with the pipe blank in a subsequent operation. 3. A method according to claim 1, characterized in that the partition wall is achieved by compressing two ridges pressed into the blank, which in a subsequent operation are sealingly connected to each other. Method according to one of Claims 1 to 3, characterized in that discontinuities (19) are produced in the strip which, after bending the tube blank, end up on the inside thereof. 5. A method according to any one of claims 1-4, characterized in that the closed end portion of each tube blank is bent about 90 °, so that the bent end portions (15) together form the heat exchanger. (1) one gable (14). ' A method according to any one of claims 1 - 5, characterized in that the bent strip is plated with a solder before said joining. Method according to claim 6, characterized in that the lamella assembly (4) and the tubes (3) provided with a partition wall (7) are packed into said heat transfer package (2), which is then heated for soldering the lamella assembly. (14) and the pipes (3), whereby also the partition wall (7) was soldered. 8. A method according to claim 7, characterized in that the soldering takes place under vacuum. Method according to one of Claims 1 to 8, characterized in that a strip of a lamella assembly (4) is provided with perforations and folded in the longitudinal direction to form the lamella assembly (4). 10. A method according to claim 9, characterized in that the perforations are formed by slits extending in the longitudinal direction of said second band, that the slits are placed in rows with a width corresponding to the thickness of the finished lamella assembly, and that the slits have at least one edge is bent out of the plane of the band.