DK2447626T3 - Heat exchanger, in particular for use in refrigerators - Google Patents

Description

The invention concerns a heat exchanger with a base section made from metal which is connected at one of its ends to an inlet facility (21) and at its other end to an outlet facility (22) for a refrigerant. Such a heat exchanger is particularly used for refrigeration units, for example refrigerators, freezers, fridge/freezer combinations.

Recognized heat exchanger devices for refrigeration units normally have a serpentineshaped bent pipeline between an inlet for a refrigerant and the outlet for the refrigerant. Such pipelines have a cross-section in the form of a circular hollow chamber and, for the heat exchanger, a comparatively small heat exchanging surface. This is expressed in a large hydraulic diameter. Long lengths of pipe are required for the required heat exchange performance, which is connected with significant pressure losses between the inlet facility and the outlet facility for the refrigerant. This requires appropriately dimensioned compressors, whereby, the energy consumption increases.

An improvement is attained by using multi-chamber hollow profiles as the base section for the refrigerant line. In the German patent application DE 10 2007 023 696 A1, is such a refrigerant line made from a serpentine-shaped multi-chamber hollow profile. Due to the corresponding number of chambers, the wettable inner surface is increased, whereby, the hydraulic diameter of such a refrigerant line reduces. The hydraulic diameter (Dh = 4A / U) is the quotient of the four-fold flow cross-section and the circumference wetted by the refrigerant. The smaller the value for the hydraulic diameter, the more energy efficient is the heat exchanger. In order to attain a sufficient temperature differential from such a heat exchanger, a comparatively long refrigerant line is required, or a method is provided to increase the exchange of heat, for example, as established for heat exchangers used in vehicle air-conditioning systems, namely lamellae, that are arranged between the multichamber hollow profiles and, for multi-chamber hollow profiles made from aluminium material, are connected by a brazed connection. Such lamellae increase the heat exchange surface, however, increases the cost of the heat exchanger due to the brazed connection required. A serpentine-shaped multi-chamber hollow profile is familiar from the patent US 4,298,062, whereby, this multi-chamber hollow profile is provided to increase the exchange of heat using protruding ribs. For further improvement of the exchange of heat, it is suggested to enlarge the ribs.

The task of the present invention is to provide a heat exchanger, in particular for use in refrigeration units, which has a high performance of exchange of heat and can be easily manufactured.

This task is solved by a heat exchanger with the characteristics of claim 1. With the new heat exchanger in accordance with the invention, a minimum of one base section is made from metal, preferably from aluminium or an aluminium alloy, existing as refrigerant line, arranged between an inlet facility and an outlet facility and connected to the respective devices. As in the usual manner, the base section can be a serpentine-shaped or meander-shaped line between the inlet facility and the outlet facility, i.e. originating from the inlet facility, the base section a first profile section, where the refrigerant is transported in the main direction of flow. The refrigerant line is bent at a deflection location and the direction of flow is changed. The refrigerant is further transported in a second profile section against the main direction of flow and then, at the next deflection location, again in the opposite direction, namely, deflected into the main direction of flow. This is repeated until the refrigerant reaches the outlet facility. Thus, the refrigerant line formed by the base section encompasses the first profile sections for the flow of refrigerant in the main direction of flow, as well as second profile sections for the flow of refrigerant in the opposite direction to the main flow, as well as bent profile sections at the deflection points of the direction of flow, between the first and second profile sections. This is comparable to state-of-the-art technology devices. For the heat exchanger in accordance with the invention, an agent is also provided that increases the exchange of heat with the ambient air or with an additional fluid flowing traverse, preferably a cooled air flow. Flowever, hereby it is not the familiar lamella, which must be connected to the base section by a brazed connection, but the base section itself is formed to increase the exchange of heat, namely the first and second profile sections. These profile sections have multiple deformations transverse to the main direction of flow.

Such deformations could be undulations in the profile, so that the profile progresses from one deflection location to the opposite deflection location in a wave-shape, preferably sinusoidal. Another option is that the profile is formed about an axis in the main direction of flow and in the opposite direction of flow, thus, it is distorted, so that the result is a spiralshaped route. Another option of deforming the base section is presented by a transposition, i.e. rotating about the longitudinal axis of the profile.

The base section is an extruded, flat multi-chamber hollow profile with two parallel wide sides and two curved narrow sides. In accordance with the invention, differently aligned deformations are provided for adjacent rows of the respective profile sections of the base section and/or adjacent multi-chamber hollow profile rows of a profile row combination that form the base section.

The extruded, flat multi-chamber hollow profile has a cross-section width of between 5 mm and 32 mm, a height of between 0.6 mm and 3 mm and a wall thickness of between 0.1 and 0.5 mm. The number of chambers in such a multi-chamber hollow profile is between 0.5 chambers/mm width of the base section to 2 chambers/mm width of the base section, The chambers of such a base section can be round, oval or polygonal cross-sections, as familiar for multi-chamber hollow profiles used for heat exchangers. After extrusion and any coating required, the multi-chamber hollow profile row is formed, for example meandered, kinked or twisted. For example, this can be carried out in sections on the profile row, i.e. the first and second profile sections provided for the heat exchanger are formed and subsequently bent at the intended deflection points so that each subsequent profile section comes to rest adjacent to or below one another. During the forming procedure, the chambers of the multi-chamber hollow profile are retained. A preferred form of design for a heat exchanger for refrigeration units has profile sections of the base section with sinusoidal undulations, i.e. the multi-chamber hollow profiles are bent during a forming procedure. Thereby, the forming force presses from the top and below against the wide sides of the multi-chamber hollow profiles so that the result is sinusoidal undulations of the profile sections with peaks and depressions. The individual peaks and depressions can be generated successively or simultaneously on a profile section, depending on the forming device used.

If an undulating profile section in the main direction of flow, following a profile section that transports the refrigerant in the opposite direction to the main flow, also has undulations it is preferred that peaks and depressions of the previously mentioned profile sections are provided so that each peak of a first profile section is adjacent to a depression of a second profile section. In this manner, a particularly good performance of heat exchange can be attained, e.g. with the ambient air or an air flow directed into a cross flow.

In another preferred form of design, a compact heat exchanger can also be produced by the use of multiple base sections, whereby, each base section has formed first and second profile sections, i.e. undulating, transposed or twisted profile sections. Each individual base section has a refrigerant line which is located at one level and, so to speak, results in one layer. Multiple base sections in the heat exchanger then means multiple layers, whereby, each base section is preferably connected to the same inlet and outlet facility. Such an inlet or outlet facility can, preferably, be an extruded profile unit made from aluminium material that has corresponding recesses, depending on the number of base sections provided in the heat exchanger. Connection of the end of the base sections to the inlet or outlet facility can be carried out easily by torch brazing, also using other recognized options of connecting. The previously mentioned multiple layers in the heat exchanger is preferred, as with the recognized application in refrigeration units, separated from one another by separating plates. Such separating plates can be made from plastic or an aluminium alloy. The separating plate can be a plastic plate, a smooth sheet or a perforated sheet, a grid or extended metal separating plate. Connection of the base sections to the separating plates can be carried out by positive locking and/or forced locking and/or material bonding, the easiest is by using a mechanical clamping. Brazed connections are also an option. However, the advantage of the heat exchanger in accordance with the invention is that easy forming is possible and there is no requirement for a brazed connection and, thus, a comparatively expensive procedural step is dispensed with.

If heat exchanges have multiple base sections, i.e. multiple layers of formed base profiles arranged above one another, the overall height of the formed base sections is selected at between 3 mm and 50 mm.

The advantage of the heat exchanger in accordance with the invention is that it has a very small hydraulic diameter. Due to this, less refrigerant is required. Smaller compressors can be used in refrigeration units and less energy required. Another advantage is the simple, homogeneous material design, comprising of extruded base sections and possible extruded inlet facilities and outlet facilities that can be easily connected to one another by torch brazing. An expensive coating of brazing medium for a brazed connection, e.g. to connect lamellae and multi-chamber hollow profiles, known from the state-of-the-art technology, is not required for the base sections.

The selection of the aluminium alloy, namely 1XXX-, 3XXX-, 5XXX-, 6XXX- alloys, in particular AlMgSi or AIMg alloys depend on the strength and corrosion resistance of the heat exchanger required, thus, according to its application. The heat exchanger in accordance with the invention can also be advantageously used for other applications other than for refrigeration units.

To further improve the heat exchanger, ribs can be provided on the external surfaces of the base section, as for the multi-chamber hollow profiles for car heat exchangers. Another option depends on the design of the forming of the first and second profile sections. Thus, if there are spaces between the first and second profile sections, additional turbulators can be inserted into these spaces.

The invention is explained in more detail in the following examples of design in the drawings. Illustrated are:

Fig. 1: A perspective view of a heat exchanger in accordance with the invention

Fig. 2a: An undulating profile section

Fig. 2b: A transposed profile section

Fig. 2c: A twisted profile section

Fig. 3: Another heat exchanger in accordance with the invention, plan view

Fig. 4: A cross-section through a base section in accordance with Fig. 3 and

Fig. 5: Another cross-section through a base section in accordance with Fig. 3.

Fig. 1 shows a heat exchanger in accordance with the invention for use in refrigeration units. This includes two base sections, namely the base section 10 and the base section 10’. Both base sections 10, 10’ are connected at one end 11 to an inlet facility 21 and at the other end 12 to an outlet facility 22 for a refrigerant. In particular, butane or carbon dioxide is used as a refrigerant for refrigeration units. The inlet facility 21 and the outlet facility 22 are extruded profile pieces made from aluminium alloy, in particular, an AIMg alloy. The inlet facility 21 and the outlet facility 22 each have recesses, their cross-section adapted at the ends 11 and 12 of the base sections 10, 10’ that are inserted into the inlet facility 21 and the outlet facility 22 and connected using flame brazing.

The base sections 10, 10’ are extruded multi-chamber hollow profiles made from an AIMg alloy. The extruded rows of multi-chamber hollow profiles have undulations in them due to a forming process. A section of such base sections 10 with undulations 30 is shown in Fig. 2a. The base section 10 is in a multi-chamber hollow profile with multiple chambers 19 that increases the wetted internal surface for the refrigerant. The undulations 30 result in a sinusoidal devolution of the base section 10 with peaks 31 and depressions 32. As can be better seen from Fig. 1, the base section 10, 10’ has different profile sections, namely, profile sections that connect the base section 10, 10’ to the inlet facility 21 and the outlet facility 22, as well as profile sections 1, which transport the refrigerant in the main direction of flow 60 to a deflection location 17, where the base section 10, 10’ is bent to a profile section 15 and the following profile section 14 transports the refrigerant in a direction opposing the main direction of flow 60. This profile section 14 also has undulations 30. The undulations 30 end in the area of the deflection location 18, where the bent profile section 16 is located. The profile sections 15, 16 are bent so that the first profile sections 13 and the second profile sections 14 are arranged adjacent to one another. Considering the first profile sections 13, which transport the refrigerant in the main direction of flow 60 and the shape of the profile sections 14, which transport the refrigerant in the opposite direction, it is clear that the peaks 31 of the first profile sections 13 are located adjacent to depressions 32 of the second profile sections 14 and the depressions 32 of the profile sections 13 are adjacent to the peaks 31 of the profile sections 14, so that there are spaces 33 between these peaks 31 and depressions 32, through which a transversely guided flow of air can be deflected and swirled around. Furthermore, these spaces 33 can be utilized in order to induce so-called turbulators, which also induces additional swirling of the transversely guided flow of air and ambient air. In a similar manner, both base sections 10, 10’ are provided with undulations 30, i.e. the base section 10’ also has undulating profile sections with peaks 31 ’ and depressions 32’.

For better stability of the heat exchanger, a separating plate 80 is provided between the one position with the formed base section 10 and the other position with the formed base section 10’, in this case a sheet of aluminium. The connection between the base sections 10, 10’ and the separating plate 80 is carried out by clamping, not shown in this example. The separating plate 80 can also have additional holes, perforations. This reduces the weight of the heat exchanger and results in additional swirling of the transversely guided flow of air. Heating wires could be arranged on such a separating plate 80 for deicing. The separating plate can be discarded for smaller heat exchangers, because the units are relatively stable due to the forming 30 of the base sections 10, 10’.

When used for refrigeration units, the base sections 10, 10’ are coated with a bactericide and fungicide. Such a coating can be carried out after the multi-chamber hollow profiles have been extruded, similar to a recognized brazed or zinc coating.

The multi-chamber hollow profile shown in Fig. 2a, which is extruded as a flat profile, which is provided with an undulation 30, can also be transposed in the longitudinal direction of the profile after extrusion. Fig. 2b shows a profile section of such a base section 10’ with transposition 40. Another option of forming is shown in Fig. 2c. Here, a profile section 10” is shown which is curled around an axis, for example in the main direction of flow 60. The result is spiral-shaped twists of the profile row. All three base sections 10, 10’, 10” are originally flat multi-chamber hollow profiles that have attained undulations 30, transpositions 40 or twists 50. Such forming is preferably carried out for first profile sections 13 in the main direction of low 60 and second profile sections 14 in the opposite direction of flow. Bent profile sections 15, 16 are provided at the deflection points 17, 18. For all base sections 10, 10’, 10” the cross-section of the profile does not change through forming, i.e. despite forming, there are no constrictions or other reductions in the cross-section that could result in pressure losses of the refrigerant. The base sections 10, 10’, 10” have a reduced hydraulic diameter and a good heat exchanging performance with the ambient air or a fluid guided into a transverse flow, without the provision of additional lamellae.

Another advantages form of design of a heat exchanger in accordance with the invention is shown in Fig. 3. Here, a systematic view of a heat exchanger is shown which comprises of a base section 10, connected to an inlet facility 21 at one end 11 and an outlet facility 22 at the other. The base section 10 is also a multi-chamber hollow profile, however, a composite profile. The base profile 10 is shown in cross-section in Fig. 4. It comprises of three rows 1, 2, 3 that are each connected to one another at a connection point 4. The connection points 4 run in the longitudinal direction of the composite profile, between the rows 1 and 2 or 2 and 3 or other rows. In this example of design, the composite profile has a width B of 18 mm, a height of 1.7 mm and a wall thickness of 0.35 mm. Each row 1,2, 3 has four chambers 19. The width of these chambers is 1.05 mm, the wall thickness of the connection point 4 is 0.1 mm. For application in refrigeration units, the width B of the base section 10 varies between 5 mm and 32 mm, according to the extrusions, the height H of the base section 10 between 0.6 mm and 3 mm and the wall thickness D of the base section 10 between 0.1 mm and 0.5 mm. In a base section 10, for each millimetre width B of the base section 10 there are between 0.5 to 2 chambers. The cross-section shown in Fig. 4 equates to the cross-section of the base section 10 in the heat exchanger in the area of the ends 11, 12, as well in the area of the deflection points 17, 18, i.e. the bent profile sections 15 in the area of the deflection point 17 and the bent profile section 16 in the area of the deflection point 18. Emanating from the end 11 of the base section 10, an undulating profile section 13 is attached in which the refrigerant is transported, significantly in the main direction of flow 60. The undulations 30 finish before the deflection point 17 and the profile section 13 transfers into the profile section 15. The composite profile is bent in order to transport the refrigerant back to the deflection point 18, in the profile section 14, in the opposite direction to the main flow 60. The profile section 14, which is arranged above and, subsequently, below the profile section 14, has comparative undulations 30 as the profile section 13. The bent profile section 16 follows at the deflection point 18, where the direction of floe is again changed. Compared to profile section 15, profile section 16 has no undulation. The first profile section 13, which transports the refrigerant in the main direction of flow, repeats itself to the end 12 of the base section 10, the profile section 15, which deflects the direction of flow of the refrigerant through a bend of the base section 10, so that the refrigerant is directed to the other side of the heat exchanger in the second profile sections 14, against the main direction of flow 60, in order to again change the direction of flow in a profile section 16.

The profile section 13 and profile section 14 are deformed across a significant part of its longitudinal elongation. During the forming procedures, for example, force acting on the base section 10 from the top or from the bottom, the rows 1,2, 3 remaining connected after extrusion, are separated from one another in the area of the very thin composite locations 4. In this example, the undulations 30 are different for the rows 1, 2 and 3. Row 1 runs initially not formed, emanating from the end 11, row 2 is curved at the top to a peak 31 due to a forming force and the profile row 3 is formed into a depression 32 by a forming force acting from the top to the bottom. A cross-section is best presented in Fig. 5, where the profile section 13 is shown, similarly, it could also be an undulating profile section 14. It is clear that it is rows 1, 2, 3 separated from one another. With regard to the amplitude and wave length, rows 1, 2, 3 have comparatively wave-shaped characteristics, however, the wave-shaped devolution is offset, as can be seen in Fig. 3, the undulations 30 are thus, so that the offset wave peaks and wave troughs of the three undulating rows 1, 2, 3 of the profile sections 13, 14 of the one base section 10 results in a good as possible swirling of a flow of air directed into a transverse flow, comparable to the state-of-the-art technology heat exchangers comprising of multi-chamber hollow profiles with lamellae attached by brazing.

Lamellae are omitted in the invention presented. Thus, the base section 10, designed as a multi-chamber hollow profile, assumes two tasks, namely, directing the refrigerant and the lamella. The manufacture of such a heat exchanger is comparatively inexpensive, because there is no requirement for brazing coating for the multi-chamber hollow profiles and a brazing process between the lamellae and multi-chamber hollow profiles carrying the refrigerant.

Reference list: 1 Row 2 Row 3 Row 4 Connection point 10, 10’, 10” Base section 11 End of 10 12 End of 10 13 Profile section 14 Profile section 15 Profile section 16 Profile section 17 Deflection location 18 Deflection location 19 Chamber 21 Inlet facility 22 Outlet facility 30 Undulation 31,31’ Peak 32,32’ Depression 33 Space 40 Transposition 50 Twist 60 Main direction of flow 80 Separating plate B Width of 10 D Wall thickness of 10 H Height of 10

Claims (13)

A heat exchanger, in particular for use in cooling furniture, comprising an inlet (21) and an outlet (22) for a refrigerant and at least one extruded metal multi-chamber hollow profile as base profile (10, 10 ', 10 "), end (11) is connected to the input device (21) and at its other end (12) is connected to the output device (22), the base profile (10, 10 ', 10 ") comprising differently oriented profile sections (13, 14, 15, 16 ), at least first profile sections (13) for flow with the refrigerant in a main flow direction (50) and second profile sections (14) for flow with refrigerant opposite the main flow direction (50) and bent profile sections (15, 16) between the first and the second profile sections (13, 14) at turning points (17, 18) of the flow direction such that a serpentine-shaped conduit for the refrigerant is formed between the input device (21) and the output device (22), the base profile (10, 10 ', 10 ") comprising is a means for increasing the heat exchange with the air surrounding the base profile (10, 10 ', 10 ") and / or with a fluid flowing past the basic profile (10, 10', 10") in a cross flow where (10, 10 ', 10 ") first and second profile sections (13, 14) between the turning points (17, 18) as means for increasing the heat exchange each are deformed several times across the main flow direction (50) and exhibit no slats, characterized by juxtaposing strands of the respective profile sections (13, 14) of the basic profile (10, 10 ', 10 ") and / or adjacent multi-chamber profile strings (1, 2, 3) of a composite profile string, forming the basic profile (10, 10 ', 10 "), each comprising differently oriented deformations. Heat exchanger according to claim 1, characterized in that the basic profile (10, 10 ', 10 ") is an extruded and deformed multi-chamber hollow profile of aluminum or an aluminum alloy. Heat exchanger according to claim 1 or 2, characterized in that the chambers (19) have a round, oval or multilayer cross section. Heat exchanger according to one of claims 1 to 3, characterized in that the deformations of the base profile (10, 10 ', 10 ") constitute waves (30) or torsions (40) or twists (50) of the profile sections (13, 14). Heat exchanger according to one of claims 1 to 4, characterized in that the first and second profile sections (13, 14) of the basic profile (10) comprise sinusoidal waves (30) with elevations (31) and depressions (32), and wherein the basic profile (10) ) at the turning points (17, 18) is always bent such that the profile sections (13, 14) form strands which are adjacent to and below each other. Heat exchanger according to claim 5, characterized in that, with the adjacent strings of the profile sections (13, 14), the elevations (31) of the first profile sections (13) are always arranged next to the recesses of the second profile sections (14). 32) and wherein the base profile (10) comprises a cross-section with a width (B) between 5 mm and 32 mm and with a height (H) between 0.6 mm and 3 mm, wherein the basic profile (10) comprises a wall thickness (D ) between 0.1 mm and 0.5 mm where the number of chambers (19) for each 1 millimeter of the width (B) of the basic profile (10) is between 0.5 / mm and 2 / mm. Heat exchanger according to claim 5 or 6, characterized in that several basic profiles (10) are provided each in its layer with profile sections (13, 14) arranged side by side between the input device (21) and the output device (22). Heat exchanger according to one of claims 5 to 7, characterized in that further turbulators are provided which are laterally inserted into a space (33) between the elevations (31) and recesses (32) of the profile sections (13, 14). . Heat exchanger according to claim 7 or 8, characterized in that the plurality of layers of base profiles (10) are separated by separation plates (80) comprising plastics or an aluminum alloy, wherein a connection between the base profile (10) and the separation plates takes place by means of of a form-closing and / or force-closing and / or fabric-closing compound, preferably by mechanical clamping. Heat exchanger according to one of claims 1 to 9, characterized in that the total height of the deformed basic profile (10, 10 ', 10 ") is between 0.3 mm and 50 mm. Heat exchanger according to one of claims 1 to 10, characterized in that ribs are further formed on the outer surfaces of the base profile (10, 10 ', 10 "). Heat exchanger according to one of claims 1 to 9, characterized in that the input device (21) and the output device (22) comprise extruded profile pieces of an aluminum alloy. Heat exchanger according to one of claims 1 to 10, characterized in that the surface of the basic profile (10, 10 ', 10 ") is coated with a bactericide and / or fungicide.