ES2631955B1 - Folded plate heat exchanger and assembly procedure - Google Patents

Abstract

Folded plate heat exchanger and assembly procedure. # Consists of a box or housing whose six walls are assembled together once a plate with longitudinal folds is arranged inside the volume of the box; existing on the lateral edges of the plate are two tabs that are trapped, each one, in the corresponding junction between a side wall and one of the tops, upper or lower. The ends of the iron with its folds adhere to the end caps of the boxes, using resin or silicone. Two semi-spaces are thus defined inside the box, with a large surface of thermal contact between them, by the folds. For each semi-space circulates a fluid from which they exchange heat.

Description

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DESCRIPTION

Folded plate heat exchanger and assembly procedure.

Technical sector

The invention falls within the field of thermal engineering, particularly that of heat exchangers, which are widely used components in various industries and in residential applications.

Technical problem to solve and background of the invention

Within the field of heat exchangers there is a wide variety of configurations, materials, types of fluids, pressure level, and other variables. It could be said that there is also some specialization of the exchangers depending on their use. In that sense, the exchanger presented here could fit into the air-to-air heat recuperators; although its use could be extended to other purposes.

The problem is to configure a structural system with adequate mechanical resistance, which offers a large area of thermal exchange, which uses cheap materials, and which is easy to build, which leads to competitive prices.

More specifically, the elementary plate exchanger is used as the basis for the problem, which can be defined as a closed box in which it is located, fixing it on the walls of the box, a plate that divides the volume of said box in two; that due to the use of space and material, it should be elongated and not very high, placing the intermediate plate in the virtual middle plane that is perpendicular to the shortest dimension of the box, although in reality the plate can be located in any way , provided that the internal space of the box is divided into two separate semi-spaces. Making the appropriate openings in the walls of the box, the semi-spaces are configured so that one of them circulates the hot fluid, which cools, and the other half-space circulates the cold fluid, which is heated.

Several documents that state the state of the art are briefly discussed below:

US2016 / 0273842A1 describes a basic plate exchanger, useful for cooling electronic components

KR101431395B1 describes a typical plate exchanger design

CN203893728A presents a multilayer exchanger that can be considered basic or reference

RU2585130C1 describes an exchanger with many layers of corrugated sheets, so the effect is that it is a very heavy, very compact and high concentration exchanger, but nevertheless does not include description of the connection of the fluids from the outside with the internal parts corresponding.

CN103383209A describes an interchanger with several plates with folds, in a stacked position, but without touching each other, so the problem is how to maintain that arrangement and how fluid currents between layers are introduced, of which this document does not describe any contribution ( it is supposed to be resolved with other future patents)

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CN203823956U presents a cross flow changer, which in one of its directions has a folding that improves heat transmission (as if the folding were a set of fins)

US2014 / 0290924A1 describes an exchanger with tubes that are not circular, but of triangular section, so that they retain a certain analogy with the sharp edge bends

JP2016047967A presents a variant of the plate exchanger, which contains internal structures in certain plates made for other applications that imply greater pressure differences between the faces of the plates

JP2015194324A describes an alternative arrangement of multilayers, but does not address the problem of connecting external circuits with the interior

The problem to be solved is to establish materially the separation between the two semi-spaces of the fluids that are respectively cooled, which we will call semi-hot space, and of the fluid that is heated, which we will call semi-cold space; said separation behaving a physical separation surface, which is that of thermal contact between semi-spaces, which is much larger than the straight section of the box, in its larger size, which we will denote as horizontal, to refer to the semi-spaces with geometric precision, such as upper, above the plate, and lower, below it.

Explanation of the invention.

The invention consists of:

- a box of thermal insulating material, composed of six faces, paired two to two opposite each other and said pair of faces forming the closures of the box in one direction, each pair of faces being identified according to their position with respect to the direction of movement of the fluids that exchange heat, and calling end caps to those that are perpendicular to said direction of movement; upper and lower covers to the plates that close the box above and below; and lateral closures to the vertical walls that close the box when its edges are tightly joined to the end faces and the covers;

- a plate with continuous folds being arranged inside the box, selected between folds of sharp edge, wavy folds, rectangular folds or folds of any other geometry, not necessarily regular repetitive, which maintain the physical continuity of the original plate, being separated the interior of the box in two semi-spaces, one above the folded plate, and another below;

- the folded plate being topped on its sides by remaining tabs, each of them by its side, trapped between an edge of one of the side closures and a top or bottom lid of the box, securing the entrapment by the action of a seal that runs along said side edge;

- and the folded plate being secured on each end face of the box by inserting it in a layer selected between adhesive putty, setting silicone, solidifiable elastomer paste or any substance that acts as mortar, thus embedding the ends of the folded plate in said solidified layer of adhesion to the end faces of the box;

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- these extreme faces and their adhesive layers being traversed by tubes which by their position unequivocally correspond to a connection with the upper or lower half-space;

- grouping in one bundle all the connecting pipes that connect with the upper half-space, and in another bundle all the pipes connecting with the lower half-space.

The invention can be applied again to each half-space of those that are delimited by the first or main folded plate, above or below it, by providing a secondary plate, with characteristics analogous to the main one, in an intermediate position within one of those semi-spaces, delimiting two differentiated sub-semi-spaces within the original semi-space, and the secondary plate being trapped on its sides by its flanges, which are gripped by the side joints that are tightened by the union of the side panels with the corresponding lid of the box. This tightening can be done by screws, or by flanges, or by previous brackets. The subdivision of a previous sub-space into two independent volumes, is applied repeatedly as required, observing in each case that the penetrations of tubes by each end face are grouped together as they correspond to the fluid that cools or to which heats up.

As a variant of the invention, the assembly is described in which the tubes that cross the end faces, which are left without any gaps, are eliminated, producing the entry or exit of the fluid that moves through each semi-space, through openings in the extreme parts of each lid, upper and lower, these openings being the total gap remaining at each end of each lid, if it does not close with the extreme face of the box on that side.

Explanation of the figures

The figures, in general, are not to scale, since the relative sizes of the elements are very different: but they are representative of the invention and its operating principles.

Figure 1a shows a diagram, in straight section, of a plate with longitudinal folds and side flanges, and Figure 1b shows said plate or folded plate, inserted in a box that is the one that houses the heat exchanger.

Figure 2 shows in perspective the scheme of the assembly of the invention, although in the figure the extreme faces are not represented, but the tubes that cross them, to drive the entry and exit of each fluid.

Figure 3a shows the inner face of an end cap, where the putty, setting silicone, or adhesive elastomer can be seen, around the end of the folded plate, and 3b shows the same, but in profile elevation.

Figure 4a corresponds to a longitudinal folding in right angles, and in 4b the same folding is shown including adhered stops that are placed at the ends of the fold faces, and serve to prevent the space between folds from closing.

Figure 5a corresponds to the arrangement of inlet and outlet tubes of the fluids circulating through each semi-space in a plate with rounded folds, and 5b shows the end cap with the penetrations coinciding with the tubes of the 5th.

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Figure 6 represents an assembly with several internal plates, which leave confined space between them for a fluid to pass.

Figures 7a and 7b show the assembly in which there are no penetration tubes through the end caps, but the inlets and outlets of each fluid are produced by both ends of the top and bottom covers.

Figure 8 completes the graphic information on the case shown in Figures 7a and b.

In order to facilitate the understanding of the figures of the invention, and of their embodiments, the relevant elements thereof are listed below:

1. Iron or plate in which the folds are made

2. Folds of sharp edge

3. Iron side tabs

4. Longitudinal seal with trapped flange

5. Top cover of the case that constitutes the exchanger

6. Side facing of said box

7. Bottom cover of the case that constitutes the exchanger

8. Side facing of said box, opposite to 6

9. Tubes that pass through the end caps of said box, and connect with the upper half-space. The tubes identified with 9i connect to the lower half-space

10. Straight angle pleated iron

11. Iron with rounded folds

12. Drills in the end caps to connect with a given semi-space, in this case the lower one

13. Drills in the end caps to connect with a given semi-space, in this case the upper

14. One of the extreme covers

15. The end cap opposite the previous one

16. Folded plate included in the box under plate 1

17. Folded plate included in the box under plate 16

18. Connecting pipes with the enclosure space confined between plate 1 and top cover 5

19. Connecting tubes with the enclosure space confined between plate 1 and plate 16

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20. Connecting tubes with the enclosure space confined between plate 16 and plate 17

21. Connecting pipes with the enclosure space confined between the plate 17 and the bottom cover 7

22. Entry of the fluid into the upper half space in the transverse opening variant

23. Upper half-space fluid outlet in the transverse opening variant

24. Inlet of the fluid to the lower half space in the transverse opening variant

25. Lower half-space fluid outlet in the transverse opening variant

26. Silicone forging or bonding elastomer adhesive cords

27. Either of the two end caps, on which the ends of the folded plates are fixed

28. Adhered stops to avoid closing the space between folds.

Embodiment of the invention

The invention is embodied by assembling the six walls that make up the exchanger housing. The assemblies must be made hermetically, by any procedure to use, without this being covered by the invention. What is covered by the invention are the joints between a lateral (vertical) facing and a top or bottom cover, in which a lateral flange of the folded plate is fitted, which is trapped in that joint, along all of it, using a joint, simple or double, hermetically sealed, its material selected from rubber, silicone, plastic or any material that has an elastic deformation field that covers the maximum expected distortion in the plane of the flange.

From the six walls of the box, plus the folded plate and with its two side tabs, plus the joints, plus the screws, brackets or flanges of conventional union between walls of the chosen material, the assembly procedure consists of a first joining phase the two lateral walls to the upper and lower covers, trapping each side flange of the plate in its corresponding connection between a lateral wall and one of said covers; and of a second phase in which the end caps are assembled, in which silicone or resin cords or setting elastomer are previously adhered, the cords having the same geometric configuration as the straight section of the plate with the folds, adjusting each cover to the rectangle formed by the previous assembly between the upper and lower covers and the lateral walls, each end of the plate being completely embedded in the inner adhesive cords of each end cover.

In the basic version of the invention, each cover must come with the drills made in the places provided so that they are above or below the zigzag row of the adhesive cords, or with the tube fittings inserted in said holes.

In the multi-plate version, and therefore multiple individually confined sub-spaces, the covers must be prepared with the corresponding multiplicity of zigzag adhesive cords, and the corresponding holes in the areas between cords.

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In the version of end caps without drills, the upper and lower covers are shorter than the side walls, but the first phase includes the assembly of said walls and covers, including the eyelashes' trapped socket in their corresponding joint; and the second phase is the same as that described in the basic procedure, only that each end cap only joins the ends of the side walls, but not the top and bottom caps; having edemas that join the free spaces left in the upper and lower covers to the external means, or conduits, that are used to carry or carry each fluid.

When the folds leave little space between them, it is advisable that the assembly includes stops attached to one of the faces that give the intermediate space, and bump with its tip or face against the opposite face, in said space. Under these conditions, when fixing the ends of the folded iron on the corresponding end plates, instead of depositing the resin or silicone cords on the inner faces of the end caps, a complete patina of adhesive material is deposited on them the one that sticks the edges of the folding, of that end.

The materials to be used must be compatible with each other, which depends on the function to be performed by the exchanger. It must also be taken into account that the stiffness required of the plate, and of each of its folds, depends on the difference in pressures between both fluids, and therefore the thickness of the plate must be greater for greater pressure differences.

As a representative example, the recovery of heat in the ventilation of premises in winter can be presented. Assume a room temperature of 20 ° C and outside of -10 ° C; and that an air mass of 0.30 kg / s with a density of 1.2 kg / m3 has to be renewed; which implies a flow of 0.25 m3 / s (which actually fluctuates slightly due to temperature variations from one part to another). If we choose 2.5 m / s as the design speed, the straight section of each circuit, the entrance and exit of the ventilation, will be 0.1 m2, which in total make 0.2 m2 of straight section of box. If we take a height of 0.2 m, the width would be 1 m. If the zigzag arrangement of the folding is that the distance between vertices of successive folds is 0.01 m, there will be 100 folds, each 0.2 m, which totals 20 m in length of the zigzag. To calculate the necessary length it is necessary to specify what thermometric performance we want, and what is the coefficient of heat transmission that is through the plate. The latter is dominated by air convection, and with the chosen speed it will be around 10 W / m2K, and we choose this amount per rounding calculation. If we now look for a 80% thermometric performance, it will mean that the flow temperature of the air that comes from outside, once heated in our recuperator, will be 0.8 (20 - (- 10)) = 14 ° C. That means that the average log temperature difference between the output and the input current is 6 ° C, and therefore we have that the thermal power transmitted is

Q = 0.30 (kg / s) 1 (kJ / kgK) 24 (K) = 7.2 kW

As the air is heated from outside 24 ° C (or 24 K) and its specific heat is 1 (kJ / kgK), which leads to 7.2 kW; which leads to require an area of heat transfer A dad by

7,200 = 10 W / m2 K • 6 (K) • A (m2)

What gives A = 120 m2, which implies 6 m in length. In principle it can be considered that this length is too long, especially to make the folding very regularly. That problem is palliated by connecting several exchangers in series. For example 6 of 1 m.

It should be noted that for this purpose plastic or wood can be used for the walls, and aluminum (paper type or somewhat thicker) for the plate, although plastic, of reduced thickness, could also be used. Even if its conductivity were bad, of 0.5 W / m K for example, if its thickness is 0.5 mm its equivalent transmission coefficient 5 would be 1000 W / m2K, that is, its thermal resistance would be negligible with respect to the which opposes air convection.

Once the invention is clearly described, it is noted that the particular embodiments described above are subject to modifications of detail 10 provided that they do not alter the fundamental principle and essence of the invention.

Claims (4)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 1. Folded plate heat exchanger, consisting of a box of thermal insulating material, composed of six faces, paired two to two opposite each other and said pair of faces forming the closures of the box in one direction, identifying each pair faces according to their position with respect to the direction of movement of fluids that exchange heat, and calling end caps to those that are perpendicular to said direction of movement; upper and lower covers to the plates that close the box above and below; and lateral closures to the vertical walls that close the box when its edges are tightly joined to the end faces and the covers, characterized in that - a plate or plate with continuous folds is arranged inside the box, selected between folds of sharp edge, wavy folds, rectangular folds or folds of any other geometry, not necessarily regular repetitive, that maintain the physical continuity of the original plate , the interior of the box being separated into two semi-spaces, one above the folded plate, and another below; - the folded plate being topped on its sides by remaining tabs, each of them by its side, trapped between an edge of one of the side closures and a top or bottom lid of the box, securing the entrapment by the action of a seal that runs along said side edge; - and the folded plate being secured on each end face of the box by inserting it in a layer selected between adhesive putty, setting silicone, solidifiable elastomer paste or any substance that acts as mortar, thus embedding the ends of the folded plate in said solidified layer of adhesion to the end faces of the box; - these extreme faces and their adhesive layers being traversed by tubes which by their position unequivocally correspond to a connection with the upper or lower half-space; - grouping in one bundle all the connecting pipes that connect with the upper half-space, and in another bundle all the pipes connecting with the lower half-space. 2. Folded plate heat exchanger, according to claim one, characterized in that a secondary plate, with characteristics analogous to the main one, is disposed in an intermediate position within one of the semi-spaces between the main plate and one of the covers, upper or lower, delimiting the secondary plate two differentiated sub-semi-spaces within the original semi-space, and the secondary plate being trapped on its sides by its tabs, which are gripped by the side joints that are tightly joined by the joint of the side panels with the corresponding lid of the box, producing in each case that the penetrations of tubes by each end face are grouped together according to the fluid that cools or heats up. 3. Folded plate heat exchanger, according to claim one, characterized in that the inlet and outlet of the fluid that moves through each half-space is produced through openings in the end portions of each top and bottom lid, being able to be these openings the total gap left at each end of each lid, if it does not close with the extreme face of the box on that side. 4. Folded plate heat exchanger assembly method, according to claim one, characterized in that the assembly consists of a first phase of joining the two lateral walls to the upper and lower covers, trapping each side flange of the plate in its joint corresponding between a side facing and a 5 of said covers; and of a second phase in which the end caps are assembled, in which silicone or resin cords or setting elastomer are previously adhered, the cords having the same geometric configuration as the straight section of the plate with the folds, adjusting each cover to the rectangle formed by the previous assembly between the upper and lower covers and the lateral walls, 10 each end of the plate being fully embedded in the inner adhesive cords of each end cap; each end cap having the holes made in the places provided so that they are above or below the zigzag row of the adhesive cords. 15 5. Folded plate heat exchanger assembly procedure, according to first, third and fourth claims, characterized in that the assembly includes stops adhered to one of the faces that give the intermediate space between folds, and bump said stops, with their tip or end, against the opposite face in said space. 20 6. Folded plate heat exchanger assembly procedure, according to first, third and fourth claims, characterized in that the resins or the silicone, or the adhesive is fixed on the inner faces of the end caps as a complete patina of material, in which the edges of the folding of the plate are nailed, by the corresponding end. 25