CH635922A5 - SPIRAL ENCLOSED HEAT EXCHANGER AND METHODS OF MAKING SAME. - Google Patents

Description

The object of the invention is to produce a heat exchanger with a spiral wall forming an enclosure making it possible to achieve high performance and to be manufactured at low cost, which can be associated with a burner, and allowing heat exchanges between more of two fluids.

To this end the invention relates to a heat exchanger between at least two fluids characterized in that it comprises a spiral wall, with closure means mounted at its two ends perpendicular to itself, arranged so as to forming a spiral enclosure for the circulation of one of the fluids between the turns of the wall, and means for the circulation of the other fluid.

The exchanger may include one or more of the following characteristics:

a) Obstacles are formed inside and / or outside the hollow wall so as to form one or more courses creating eddies.

b) The faces of the hollow wall are joined together at a plurality of points so as to constitute an interior path in baffles between two adjacent faces and asperities and recesses between the turns of the hollow wall.

c) The meeting points of the faces are welding points.

d) The spiral wall has three faces so as to constitute two internal spiral paths, the meeting points of a two-sided system being further apart than those of the other two-sided system, so that the speed of circulation in a course is different from that existing in the other course.

e) The spiral wall has faces so as to constitute n-1 internal spiral paths, the meeting points of each system of faces having a different spacing from that of the other systems, so as to obtain different circulation speeds between all systems.

f) The spiral wall is arranged vertically and closed on itself and a suction device is mounted laterally at its lower end so as to entrain the condensed fluid and / or the mist at the lower part of the device.

g) The spiral wall is arranged vertically and closed on itself and a suction device is mounted under its central region so as to entrain the condensed fluid and / or the mist at the bottom of the device.

h) The spiral wall is arranged vertically and closed on itself and a discharge pipe with removable closure is mounted at its lower part so as to draw the condensed fluid from the lower part of the device.

i) The sealing means at the two ends of the wall are formed by the union of the lower and upper extensions of the opposite faces of the hollow wall.

j) The union of the extensions of the opposite faces of the hollow wall is a weld or a stapling.

k) The central space or the external region of the vertically placed exchanger is configured as a combustion chamber where a burner is housed.

1) The surface of the wall of the combustion chamber according to k / is treated so as to absorb the radiation from the burner flame, in order to lower the temperature of the burner material.

m) At least certain points of welding of the faces of the hollow wall are drilled in their center in order to allow the rupture of the boundary layers of the fluid circulating between the turns of the hollow wall.

n) Means are arranged between the spiral space and the suction device to bring to the latter a flow of heat in order to heat the saturated vapors entering the suction device.

o) The spiral winding of the hollow wall is with variable pitch in order to optimize the heat exchange by increasing the pressure drop inversely proportional to the temperature gradient of the fluid circulating between the turns of the hollow wall.

p) The spacing of the welding points of the hollow wall is variable in order to increase the exchange by turbulence as the temperature gradient of the fluid circulating between the turns of the hollow wall decreases.

q) The winding of the turns of the hollow wall has a conical conformation with vertex upwards so that the spiral space and the hollow wall are inclined to the horizontal, thus facilitating the condensation of the fluid (s) and the condensate drain in the lower part of the exchanger. A first method of manufacturing the heat exchanger, according to the invention is characterized in that two or more sheets are placed one on the other, they are joined by numerous weld points, the edges, a pressure is applied between the sheets, the space between the sheets is filled with a product capable of being eliminated, the bending is carried out and the above product is eliminated.

A second method of manufacturing the sela heat exchanger of the invention is characterized in that two or more sheets are placed one on the other, they are joined by numerous welding points, by welding the edges , a traction is exerted on the sheets during the spiral conformation, and a pressure is applied between the sheets to obtain the swelling.

In order to better understand the invention, several embodiments will be described, by way of example, with reference to the appended drawings, in which:

Fig. 1 shows an elevational view of an embodiment of the exchanger according to the invention;

Fig. 2 shows a perspective view of the exchanger shown in Figure 1;

Fig. 3 shows a developed view of the exchanger shown in Figures 1 and 2;

Fig. 4 is a perspective view of a portion of the wall constituting the exchanger before winding;

Fig. 5 is a perspective view with cutaway of the exchanger presited whose wall has punctures;

Fig. 6 is a similar view of a portion of the wall of the exchanger according to FIG. 5 before winding;

Fig. 7 is a similar view very schematically showing a device for heating the burnt gases;

Fig. 8 shows a perspective view of another embodiment of the invention;

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it was moved at a portion of the hollow wall of the exchanger of FIG. 8 before winding;

Fig. 10 is a partial section of the hollow wall in the case where there is exchange between three fluids;

Fig. 11 is a schematic perspective view of a heat exchanger, in the case of an exchanger between three fluids, the exchanger being associated with a centrally mounted burner and with a draft fan;

Fig. 12 is a partial vertical section of the exchanger of FIG. 11 passing through the axis of the draft fan; io

Fig. 13 is a partial horizontal section of the hollow wall of the exchanger of FIG. 11 showing the connection with the fluid outlet tubes;

Fig. 14 is a schematic perspective view of a heat exchange in the case of an exchange between three fluids, the exchanger being associated with a burner placed outside the spiral wall and with a fan mounted centrally;

Fig. 15 is a partial vertical section of the exchanger of FIG. 14 passing through the burner; and 20

Fig. 16 is a partial section of the hollow wall similar to that of FIG. 10 showing welded points drilled in certain places.

FIGS. 1 and 2 show a heat exchanger with two fluids, each of the fluids being indicated respectively by the references A and B; the direction of circulation of each of the fluids is indicated by arrows. The exchanger comprises a network of tubes 1 for the circulation of the fluid B, these tubes being integral with a wall 2 in contact with said tubes by their generatrices.

In the embodiment shown, the network of tubes and the wall are constituted by the wall known in the trade under the name of "Roll-Bond" (FIG. 4). This wall is obtained by partially welding two sheets a and b of aluminum alloy or stainless alloy, and leaving strips not welded. Thanks to inflation by suitable means at the non-welded locations, tabular regions c are obtained which constitute the tubes 1 described above. It is understood that the product obtained is particularly suitable for manufacturing evaporators of domestic refrigerators or freezers.

As can be seen more particularly in FIG. 2, the wall is shaped in a spiral so as to reveal between the successive turns a space 3 in which the fluid A in this case circulates. In order to confine the fluid A in a 4s circuit determined, the exchanger comprises sealing members constituted by covers 4.5 made integral with the upper and lower edges respectively of the wall 2 so as to provide for the fluid A an inlet 6 and an outlet 7. Of course, the central turn 8 is not completely closed on itself so as to allow the circulation of the fluid A.

FIG. 3 shows a developed view of the wall 2 and of the network of tubes 1 for the circulation of the fluid B. This network is constituted by a set of collectors 1 a, ss connected together by tubes 1 connected in parallel between collectors 1 a. The direction of circulation of the fluid B is indicated by the arrows and this is sufficiently explicit so that it is not necessary to describe the process thereof.

The fluid is in fact forced to go from a collector to the next 60 by the existence of obstacles such as the interruption 9 between two collectors. Note that the networks of tubes 1 are arranged substantially perpendicular to the direction of circulation of the fluid A.

We will now explain the operation of the exchanger, an embodiment of which has just been described, with reference to a type of use in which the fluid A is in the gaseous state, for example consists of gases. combustion, and the fluid B in the liquid state, for example is formed by water from a heating circuit. Given the pressure losses opposing the flow of fluids in the exchanger, it goes without saying that these are drawn or sucked by a drive member, for the fluid A as well as for the fluid B. These members are well known in themselves and have therefore not been shown. The gases penetrate axially at high temperature through the inlet 6 of the space 3, undergo a change in direction of flow substantially at 90 ° and then flow towards the outlet 7. The return water from the heating circuit enters the network. of tubes 1 against the gas flow, that is to say on the side adjacent to the gas outlet 7 then flows towards the central spiral 8, and is evacuated towards the start of the heating circuit in the inlet area 6 of the gases. During their progression, it is understood that the gases cool in contact with the walls of the exchanger in which the cooler water from the heating circulates. Conversely, the water gradually heats up as in any methodical exchange process.

The constitution of the network of tubes 1 as shown in FIG. 3 makes it possible to obtain a significant division of the flow of fluid B in the tubes 1 and consequently therefore to reach both a large exchange surface and a significant circulation speed in tubes, which improves the exchange coefficient. In this way, an extremely efficient exchanger is obtained. In the above application, this makes it possible to reach the dew point of the smoke for condensing operations.

In order to improve the efficiency of the exchanger described above, it is possible to form on the surface of the wall 2 which is not in contact with the outside, discontinuities constituted by punctures 10a, 10b, 10c which cross the entire wall as seen in FIGS. 5 and 6. These punctures can be of small dimensions like the punctures 10a, of elongated shape and located near one end of the device like the punctures 10b, or of an even more elongated shape like the punctures 10c.

These perforations may naturally only exist on certain turns. The leading edges of these perforations break the boundary layers, which increases the efficiency of the device. In addition, the perforations significantly reduce the pressure losses due to the circulation of the fluid in the spiral space.

As explained above, the discontinuities can also be formed by recesses over part of the thickness of the wall, or by projections or by a combination of these three discontinuities. They may also only exist on a part of the surface of the wall 2 which is not in contact with the outside.

To further increase the yield, the spiral wall is conformed so that the spacing between the turns decreases progressively towards the outlet of the burnt gases, so as to increase the heat exchange as the temperature of the gases decreases.

Finally, a simple device operating the drying of the burnt gases is shown very schematically in FIG. 7.

A U-shaped element 11 has been mounted on the upper cover 4. A flow derived from the fluid A arrives at Ai at one end of the U-shaped element and exits at A2 where it comes to mix with the fluid A to dry it. .

We will now describe another preferred embodiment, of even better efficiency, of easy construction, and allowing heat exchanges between more than two fluids.

FIG. 8 shows an exchanger with two fluids, each of the fluids being respectively designated by the letters A and B, and the direction of circulation of the fluids being indicated by arrows. Fluid A is, for example, hot air and fluid B is water.

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The exchanger consists essentially of a vertically arranged hollow wall 101 in a spiral, here having two faces 101 a and 101 b (FIGS. 8 and 9). This wall is obtained by placing one on the other of two stainless steel sheets, for example 101a, 101b and by welding them to each other by means of numerous welding spots 102. The sheets are planar or previously embossed. The weld spots are preferably made by means of programmed resistance welding knobs. All the edges are then welded, leaving beyond the weld non-welded bands which will later be brought together after shaping to arrange the space between the external faces of the hollow walls, as will be seen below.

Thanks to a high pressure which is applied between the two sheets, for example hydraulically, the swelling is obtained at the non-welded locations as seen in FIG. 9. This results in a hollow wall with two faces having numerous points of junction between the two faces. To then obtain the spiral conformation, the space between the sheets is first filled with a product capable of being eliminated, for example a soluble or sublimable salt. Indeed if this precaution is not taken the sheets will apply during bending. Then we do the bending,

after which the salt is removed by dissolution or sublimation.

The hollow spiral wall thus obtained constitutes a path 103 in baffles for one of the fluids, for example fluid B.

Another method for obtaining the hollow spiral wall, without the intervention of salt, consists in shaping the sheets after welding by exerting a traction on them during the winding. This traction prevents the compression of the sheet which has the smallest radius. The inflation is then carried out after conformation, possibly after annealing.

The wall has been shaped in a spiral so that the turns are brought together, leaving a central recess 104 in the center, the utility of which will be seen below. There is therefore between the turns a space 105 in which the other fluid circulates, for example the fluid A. A cover Ci closes the upper end of the device while the lower end is closed by a wall C2.

In the example of Figure 8 there is shown very schematically a burner 106, placed centrally, to pass hot air between the turns, while the fluid B, for example water, is introduced into the path 103 of the hollow wall by a tube 107, and leaves it by a tube 108. Naturally suction or discharge devices, conventional or not, are necessary to obtain the circulation of the fluids but they have not been shown for simplify.

It is understood that the path of the two fluids is neither completely straight nor completely helical. In addition, the numerous weld points constitute for the interior path 103 a path in baffles. These weld points also form on the external faces of the hollow wall asperities and recesses so that the space 105 also causes eddies in the circulation of the fluid A. This similar action on each fluid is eminently favorable to the heat exchange.

The constructive principle of the hollow wall makes it possible to constitute several routes inside the wall. FIG. 10 shows a wall with two paths, a second path 109 being formed by virtue of a third substantially flat sheet 101c, the weld points of which with the sheet 101a are, for example twice as close as the weld points of the path 103. This makes it possible to obtain, if the fluid B is water, both water for heating and water at a lower temperature, for sanitary use.

FIG. 11 represents a heat exchanger according to the invention in which the hollow wall has two paths. To the two tubes 107, 108 of the previous example, two tubes 110, 111 have been added corresponding to the path 109 of FIG. 10. FIG. 13 shows how the tubes 108, 111 are connected respectively to the paths 103 and 109. Here the exchanger is associated with a burner 106 placed centrally, which is shown very schematically, and with a fan 112 actuated by a motor 113, mounted at the lower part of a wall 114 made of sheet metal, which laterally closes the space in a spiral and forms a space for outside clearance to the spiral. The fan acts through its orifice 115. Naturally the fluids in the paths 103 and 109 are set in motion by circulation pumps mounted on the tubes connected to the tubes 107, 110 or 108, 111. These pumps have not been shown to simplify the drawing.

The fan 112 not only drives the gaseous fluid but also the condensed fluid and / or the mist at the bottom of the device. This condensed fluid can also be evacuated by a discharge pipe 116, with removable closure, not shown.

We see at 117, shown very schematically, a pipe bringing to the orifice 115 of the fan a flow of heat coming from the spiral space in order to heat the saturated vapors entering the fan.

As in the example shown in Figure 8, we see a cover Ci at the top of the device, but in reality the shutter both above and below is obtained in another way shown in the figure 12. It can be seen that the opposite faces 101 b, 101 c, for example, of the hollow wall have been extended, bent and brought together, then welded or stapled at their upper and lower ends.

In the embodiment shown in Figures 14 and 15, the spiral wall was bent at its outlet end so as to form a bulge 118, constituting a combustion chamber for a burner 106 shown very schematically. On the other hand, the fan 112 with its motor 113 has been mounted under the central region 104 of the device.

The surface of the combustion chamber, in this embodiment, as in the embodiment of FIG. 11 is advantageously treated so as to be preferably blackened. Indeed, this surface thus treated partially absorbs the intense radiation of the burner flame, which largely lowers the temperature of the material of the burner and increases the longevity of the latter.

Finally, FIG. 16 shows a portion of the spiral wall in which the facing weld points have been drilled in their center at 119. This arrangement allows the boundary layers of the fluid flowing between the turns of the hollow wall to be broken.

It is indicated that the stainless steel sheets 101, 101b and 101c mutually welded to the points 102 have a thickness of between 0.3 and 0.8 mm, preferably of the order of 0.4 mm, that the spacing of the points 102 is understood between 15 and 50 mm, preferably being of the order of 35 mm for the heating water path, that the number of turns of the exchanger is between 2 and 10 being preferably of the order of 4 or 5, that the mutual spacing of the turns is between 10 and 30 mm and that the hydraulic pressure used to "open" the paths reserved in the hollow wall for the fluid B after completion of the welding points is between 20 and 40 bars in the event that none of the mutually welded sheets is previously embossed, that is to say deformed so as to materialize depressions at the weld points to be formed.

The overall size of the exchanger obtained is much smaller than that of known exchangers of comparable exchange heat capacity, its volume excluding s

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everything being several times lower than those of these known exchangers.

It goes without saying that the embodiments described above and represented in the drawings are given only by way of nonlimiting examples. Thus, instead of suction devices, delivery devices could be used. Similarly, the spiral winding could be of variable pitch in order to optimize the heat exchange by increasing the pressure drop in a manner inversely proportional to the temperature gradient of the fluid providing the heat. Finally, the spacing of the welding points can be variable in order to increase the exchange by turbulence as the temperature gradient of the fluid circulating between the turns of the hollow wall decreases.

We have not shown in the drawings all these variants 5 which are understood without drawings. Likewise, the winding of the turns of the hollow wall could be given a conical conformation with the top upwards so that the spiral space and the hollow wall are inclined to the horizontal, to facilitate the condensation of the fluids and the io condensate flow. We also did not consider it useful to represent this variant which we understand immediately.

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Claims (21)

635922 2 \. Heat exchanger between at least two fluids, characterized in that it comprises a spiral wall, with sealing means mounted at its two ends perpendicular to itself, the wall and these means being arranged so as to form a spiral enclosure for the circulation of one of the fluids between the turns of the wall, and means for the circulation of the other fluid. 2. Heat exchanger according to claim 1, characterized in that the means for the circulation of the other fluid consist of a network of tubes integral with their generatrices of the spiral wall and parallel to an axis around which the wall. 3. Heat exchanger according to one of claims 1 and 2, characterized in that the spiral wall has on its surface which is not in contact with the outside discontinuities in hollow or projecting of any shape in order to constitute leading edges for the circulation of the fluid in the continuous spiral enclosure. 4. Heat exchanger according to claim 1, characterized in that the means for the circulation of the other fluid consist of the wall itself, which has at least two parallel faces joined together on two parallel edges, so to form a hollow wall allowing the circulation of the fluid. 5. Heat exchanger according to claim 4, characterized in that obstacles are formed inside and / or outside the hollow wall so as to form one or more paths creating eddies. 6. Heat exchanger according to claim 5, characterized in that the faces of the hollow wall are joined together at a plurality of points by welding, so as to constitute an internal path in baffles between two adjacent faces and asperities and recesses between the turns of the hollow wall. 7. Heat exchanger according to one of claims 4 to 6, characterized in that the spiral wall has three faces so as to constitute two internal spiral paths, the meeting points of a set of two faces being more apart than those of the other set of two faces, so that the speed of circulation in a course is different from that existing in the other course. 8. Heat exchanger according to one of claims 4 to 6, characterized in that the spiral wall has faces so as to constitute n-1 internal spiral paths, the meeting points of each pair of faces having a spacing different from that of the other pairs so as to obtain different circulation speeds between all the pairs. 9. Heat exchanger according to one of claims 4 to 8, characterized in that the spiral wall is arranged vertically and closed on itself and in that a suction device is mounted laterally at its lower end of so as to entrain the condensed fluid and / or the mist at the bottom of the heat exchanger. 10. Heat exchanger according to one of claims 4 to 8, characterized in that the spiral wall is arranged vertically and closed on itself and in that a suction device is mounted under its central region so entraining the condensed fluid and / or the mist at the bottom of the heat exchanger. 11. Heat exchanger according to one of claims 4 to 10, characterized in that the spiral wall is arranged vertically and closed on itself and in that a discharge pipe with removable closure is mounted at its lower part so as to draw the condensed fluid at the bottom of the heat exchanger. 12. Heat exchanger according to one of claims 4 to 11, characterized in that the sealing means at the two ends of the wall are constituted by the union of the lower and upper extensions of the opposite faces of the hollow wall. 13. Heat exchanger according to one of claims 4 to 12, characterized in that the central space or the external region of the vertically placed exchanger is shaped as a combustion chamber where a burner is housed. 14. Heat exchanger according to claim 13, characterized in that the surface of the wall of the combustion chamber is treated so as to absorb the radiation from the burner flame, in order to lower the temperature of the material of the burner. 15. Heat exchanger according to one of claims 6 to 14, characterized in that at least certain meeting points of the faces of the hollow wall are drilled in their center in order to allow the rupture of the boundary layers of the fluid flowing between the turns of the hollow wall. 16. Heat exchanger according to one of claims 9 to 15, characterized in that means are arranged between the spiral space and the suction device to bring to the latter a flow of heat in order to heat the saturated vapors entering the suction device. 17. Heat exchanger according to one of claims 4 to 16, characterized in that the spiral winding of the hollow wall is of variable pitch in order to optimize the heat exchange by increasing the pressure loss inversely proportional to the temperature gradient of the fluid flowing between the turns of the hollow wall. 18. Heat exchanger according to one of claims 6 to 17, characterized in that the spacing of the meeting points of the hollow wall is variable in order to increase the exchange by turbulence as the gradient of the temperature of the fluid circulating between the turns of the hollow wall. 19. A method of manufacturing the heat exchanger according to one of claims 4 to 18, characterized in that two or more sheets are placed one on the other, they are joined by welding points, the edges are welded, a pressure is applied between the sheets, the space between the sheets is filled with a product capable of being eliminated, the bending is carried out and the above product is eliminated. 20. A method of manufacturing the heat exchanger according to one of claims 4 to 18, characterized in that two or more sheets are placed one on the other, they are joined by welding points, the edges are welded, a traction is exerted on the sheets during the spiral conformation, and a pressure is applied between the sheets to obtain the swelling. The present invention relates to a heat exchanger used to obtain a heat transfer between at least two fluids in movement without contact of these fluids with one another. Such heat exchangers are known and used in numerous applications and come in various forms generally comprising at least two enclosures separated by a common wall. The fluids circulate respectively in each of these chambers at different temperatures, a heat exchange being obtained through the common wall. So-us their most usual form exchangers of this type are constituted by a network of tubes constituting a first enclosure and traversed by one of the fluids, said network being inserted in a second enclosure traversed by the other fluid. We thus obtain a s 10 15 20 25 30 35 40 45 50 55 60 65 3 635,922 significant exchange surface increased in addition, in many cases, by the addition of internal and / or external wall elements, added or not. These wall elements generally take the form of fins or ribs arranged perpendicular to the axis of the tubes mentioned above. There are also known heat exchangers in which networks of parallel tubes form sheets which are wound in a spiral and are housed in an enclosure. Heat exchangers are also known in which two fluids travel in two parallel spiral paths with one another, by virtue of a spiral duct housed in an enclosure. All of these exchangers have advantages and disadvantages. In general, they are intended for heat exchange between only two fluids. Often the fins or ribs mentioned above are non-existent.