WO2010108247A2

WO2010108247A2 - Heat exchanger

Info

Publication number: WO2010108247A2
Application number: PCT/BR2010/000102
Authority: WO
Inventors: Estevão Marino de ESPÍNDOLA
Original assignee: Refrex Evaporadores Do Brasil S/A
Priority date: 2009-03-26
Filing date: 2010-03-24
Publication date: 2010-09-30
Also published as: AR075390A1; MX2011010081A; WO2010108247A3; RU2011143158A; CN102365519A; EP2438380A2; BRPI0900535A2

Abstract

The present invention refers to a heat exchanger for cooling purposes (1) provided with a plate-shaped body (5) formed by connecting two blades (4), said plate (5) being provided with a tubular circuit (6) formed between the blades (4) for the passage of a cooling fluid therethrough, said plate (5) being folded in the shape of a flattened spiral.

Description

HEAT EXCHANGER Disclosure of the Invention

The present invention refers to a heat exchanger for cooling purposes that is used particularly in refrigerators and freezers, for example, provided with an automatic defrosting system.

Heat exchangers used in cooling systems of such equipment as refrigerators, freezers and cold chambers are known, the objective of which is to remove the heat of a closed place and send same to the environment, thus producing the desired effect, such as freezing or cooling.

Amongst the types of known exchangers of heat, mention may be made to the tube-on-plate type used in freezing boxes, the roll-bond, and the finned heat exchanger for automatic (no frost or frost free) defrosting systems .

The automatic no frost defrosting system is distinguished amongst the others, because of its technology that dispenses defrosting of the equipment by the user, since it defrosts automatically.

It comprises basically an aluminum pipe coil with incased fins that may be flat or indented. When such fins are indented, a star-shaped fin assembly is formed, the so- called star fins or spin fins. The heat exchangers provided with flat fins comprise recessed plates that form the fins to be incased in the coiled pipes later on. Said fins increase the contact area of the air that passes between them to better absorb the heat from the air. The cooling gas flows through the coil, while the air from the environment flows through the fins, thus providing heat, and then returns to the environment, to cool the food.

The star fin or spin fin heat exchangers perform the same function as those provided with fins, but their fins are shaped as thin shark-indented fins that exhibit a circular star-shaped configuration when wound around the coil. Usually, both the finned heat exchangers and the star fin or spin fin heat exchangers are made with aluminum pipe and fins, however, for other applications they may show a mixed configuration, that is: aluminum fins and copper pipe . Despite the efficiency of such heat exchangers, they suffer from a number of disadvantages. They require sophisticated technology, special equipment for the manufacture thereof, require a press, equipment for cutting plates and making fins, and so on. Moreover, such finned heat exchangers or spin fin heat exchangers are delicate and any impact may impared their rather thin fins, thus making it difficult for the air to pass through the cooling system.

Another disadvantage is that the performance of the heat exchanger depends on the contact of the pipe with the fins, and in the event there is any clearance between them the fin will not reach the same temperature of the pipe, and thus the cooling may not take place properly.

Distinctly from such heat exchangers, the roll- bond type heat exchanger comprises two fusion-welded aluminum plates provided with channels for the passage of the cooling fluid therethrough. For such, prior to connecting the sheets, they are painted with the channels circuit, in such a way that the fusion-weld does not join the sheets where the paint is present. Thus, when compressed air is injected into the circuit, the pipes or channels that make out the cooling circuit are expanded.

This process is fully automatic and the thus formed heat exchanger has a more rigid structure than those cited previously. However, it is not advisable to use its shape in cooling systems provided with automatic defrosting, since its structure is flat and the available space for the heat exchanger is limited to the size of the equipment, and therefore the heat exchange is limited.

In order to eliminate these problems, the present invention is directed to a heat exchanger for home refrigerators and freezers, especially for no frost or frost free systems, by using simplified technology, and thus reducing the manufacturing costs.

Therefore, an object of the present invention is a heat exchanger manufactured by the well known roll-bond process and folded into a shape similar to a spiral, providing efficient heat exchange in the same space of the systems having finned evaporators or spin fin evaporators.

Another object of the present invention is a heat exchanger that comprises a significantly reduced number of parts in relation to finned heat exchangers, besides being a more robust product with respect to the handling, transportation and safety, thus advantageous , also reducing both the lead time and the manufacturing labor cost.

A further object of the present invention is a heat exchanger comprised of a single part whose fins are made from the same plate that forms the pipes, thus advantageously eliminating the problem of lack of contact between the pipes and the fins that occurs with the finned heat exchangers, thus preventing a decrease in the performance of the products due to the looseness of the fins on the pipes.

Another object of the present invention is a heat exchanger manufactured from the same roll-bond system that is folded in the shape of a flattened spiral, and the fins are formed in the spaces between the pipes of the loop.

The present heat exchanger is formed from a flat plate that is rolled or folded on itself and provided with louver-shaped fins formed from the plate itself, functioning as a single body of fins and cooling fluid pipes in a single assembly.

The present heat exchanger may be manufactured in several sizes without the need of high investments. Also, it is not subject to the variations in the process, accepts the conformation of a cooling loop without interference or heat exchange between the inlet and the outlet; may be provided with coaxial or parallel heat exchangers; and it makes feasible the formation of fins of any type or shape.

The heat exchanger still offers other advantages. It is a single inflated part, with louvers or fins in the horizontal and/or vertical direction that promote a disturbance in the air flow suitable to the desired performance. In view of the fact that it is a part obtained by the roll-bond process, it comprises double louvers in the cutout areas, thus increasing the heat exchange area.

Moreover, the present heat exchanger does not comprise moving parts, and the inflow and outflow of the cooler may be on the same side to use with coaxial lines; or on opposite ends to eliminate the interference of the inflow and outflow temperature.

The evaporation of the cooling gas may be through the center of the heat exchanger and the suction from outside; or the evaporation of the cooling gas may be outside and the suction through the center of the heat exchanger.

Schematic figures of the present invention are shown below, the dimensions and proportions of which are not necessarily the real ones, since the purpose thereof is to present different aspects thereof didactically, the extension of protection of which is determined only by the scope of the attached claims.

Figure 1 depicts a schematic perspective view of the heat exchanger (1) of the present invention.

Figure 2 depicts a schematic side view of the heat exchanger (1) taken as indicated by arrow II of figure 1.

Figure 3 depicts a schematic front view of the heat exchanger (1) taken as indicated by arrow I of figure 1.

Figure 4 depicts a schematic top view of the heat exchanger (1) .

Figure 5 depicts an example of a cut view of a heat exchanger in order to illustrate the air flow between fins (2) e (3).

Figure 6A depicts an extended view of detail A of figure 5.

Figure 6B depicts an extended view of a variant of the opening of the blades (41) and (42) of the louver or fin (2) .

Figure 7 depicts a schematic top view of the heat exchanger (1) before it is folded.

Figure 8 depicts a schematic perspective view of a heat exchanger (10) of the prior art.

Figure 9 depicts a schematic perspective view of one another heat exchanger (100) of the prior art. Description of the Illustrated Embodiments

As illustrated in figures 1 through 7, the heat exchanger (1) of the present invention comprises a plate- shaped body (5) formed by connecting two blades (4) , said plate (5) being provided with a tubular circuit (6) between the blades (4) for the passage of a cooling fluid, said folded plate (5) being in the shape of a flattened spiral.

Said plate (5) also comprises a plurality of louver-shaped fins (2 and 3) formed in the empty spaces between the channels of the tubular loop (6) . The fins (2 and 3) may be disposed horizontally

(2) and/or vertically (3), depending on the need. Figures 1 through 4 illustrate a heat exchanger (1) provided with fins (2 and 3) in both horizontal (2) and vertical (3) directions that resemble louvers in view of the way they are formed.

The horizontal and vertical directions of the fins (2 and 3) are referred to herein only as references to the orientation of the fins (2) and (3) with respect to each another. They are thus designated considering the top view of the heat exchanger (1) , as illustrated in figure 4, wherein the fins (2) are located in the horizontal direction and the fins (3) in the vertical direction.

As illustrated in figure 7, the heat exchanger (1) is shown in the form of a flat plate (5) before it is folded. There are spaces (21 and 31) between the channels of the tubular loop (6) where the fins (2 and 3) may be formed. The purpose of the fins (2 and 3) is to provide a increase of the heat exchange area, besides the required turbulence in the air flow (arrow III, figure 5) that passes through the heat exchanger.

If required, in addition to the fins (2 and 3) formed from the plate (5) itself, extensions of louvers may be provided in layers of materials such as aluminum or another metal, and attached to the plate (5) by any suitable method such as weld, spot clinch, rivet, adhesive, etc.

The fins (2 and 3) may be obtained by any process known in the prior art, such as stamping or drawing (spinning) ; and the stamping or drawing may be carried out simultaneously along the whole area of the plate, or punched individually in any free area around and near the channels of the loop (6) . As to the shape, the fins may have different shapes, such as rectangular, oblong, circular, or any other desired polygonal form.

Figure 5 illustrates a cross-section of an example of a heat exchanger wherein the air flow (indicated by arrow III and dotted lines) passes through the spaces between the layers of the folded plate (5) and is deviated when it contacts the fins (2 or 3), until it exits.

Since the plate (5) is composed of two blades

(4), the areas designed for the formation of the fins are prepared in such a way that, when they are punched or stamped, they delaminate, thus increasing the heat exchange area. The blades (41 and 42) of the fins (2 or 3) may be delaminated or folded on the same side (figure 6A) or on opposite sides (figure 6B) , depending on the need of turbulence and required air flow. In the event they are inlaid, there is no need of preparation for the delamination. When the fins (2 and 3) are stamped, they may be punched in just one operation (in the shape of a comb), in order to turn the blades (4) into small fins (2 and 3) to increase the turbulence and improve the heat exchange.

Other metal, composite or plastic parts designed to cause turbulence, disturbance or redirecting the air flow to attain better levels of heat exchange may also be inserted between the plates (4) . When the blades (41) and (42) of the fins (2 or

3) are folded on opposite directions (figure 6B) , a higher turbulence of the air flow that crosses the heat exchanger (1) is attained, thus improving the heat exchange, therefore increasing the efficiency of the heat exchanger

(D •

The heat exchanger (1) is obtained by the roll- bond process plus a number of steps for cutting the fins (2 and 3) thereof, such as the following: a) painting a tubular loop (6) on an alumminum plate (4); b) overlaying the aluminum plate (4) with another aluminum plate (4) having the same dimension; c) calendering the plates (4); d) positioning same in a size restrainer; e) applying compressed air to the tubular loop (6), inflating the loop until it reaches the size restrainer' s size; f) cutting the fins (2) and (3) in the empty spaces between the channels of the tubular loop (6); g) folding the blades (41 and 42) of the fins (2) e (3); h) folding the plate (5) in the form of a flattened spiral.

The process uses two plates (4) that, after receiving a painting of the desired outline of the tubular cooling loop (6), are submitted to calendering.

The plates (4) are then disposed in a size restrainer (not illustrated) so that when compressed air is applied to the loop (6) to be inflated, the opening of the channels of the circuit (6) is restricted by the restrainer. The air introduced in the circuit between the plates follows the lines of the outline, expanding the plates (4) as far as the dimensions predefined by said restrainer. This results in a plate having the channels integrated for the passage of the cooling fluid therethrough. The fins (2) and (3) are then cut in the empty spaces between the channels of the tubular loop (6), after which its blades (41 and 42) are either folded on one side or both sides. Then the plate (5) is folded in a spiral shape, thus forming the heat exchanger (1) .

Figure 8 illustrates a heat exchanger (10) of the prior art used in frost free system. Said heat exchanger (10) is provided with a pipe coil (11) having flat fins (12) encased therein. Figure 9 illustrates another heat exchanger (100) of the prior art, whose fins (102) are punched and provide a star-shaped configuration when they are rolled around the pipe (101) , reason why they are known as star fin or spin fin heat exchangers . The fins (12) and (102) of these two heat exchangers (10 and 100) , respectively, need to be disposed around the pipes (11) e (101) in order to make and keep the contact with same all the time, since otherwise they do not attain their temperature, thus decreasing the performance of the heat exchanger (10 or 100) .

A person skilled in the art will readily perceive, from the description, several ways to carry out the present invention without departing from the scope of the attached claims .

Claims

1. A heat exchanger provided with a plate- shaped body (5) formed from two blades (4) connected, said plate (5) provided with an inflated loop (6) between the blades (4) for the passage of a cooling fluid therethrough, characterized in that the plate (5) is folded in the form of a flattened spiral.

2. The heat exchanger according to claim 1 characterized in that the plate (5) is comprised of a plurality of fins (2 and 3) in the form of louvers composed of blades (41 and 42) from cutting the blades (4) in the empty spaces (21 and 31) between the channels of the inflated loop (6) .

3. The heat exchanger according to claim 2 characterized in that the fins are horizontal fins (2).

4. The heat exchanger according to claim 2 characterized in that the fins are vertical fins (3) .

5. The heat exchanger according to claim 2 characterized in that the fins are both horizontal fins (2) and vertical fins (3) .

6. The heat exchanger according to claim 2 characterized in that the blades (41 and 42) of the fins (2 and 3) are delaminated on one same side.

7. The heat exchanger according to claim 2, characterized in that the blades (41 and 42) of the fins (2 and 3) are delaminated on opposite sides.