Refrigeration unit and heat exchanger for a refrigeration unit

Abstract

A heat exchanger for a refrigeration appliance comprises a heat exchanger tube for conducting refrigerant and a plurality of fins which are arranged spaced apart from one another in a first direction, such that between two fins adjacent in the first direction, a flow channel extending in a second direction for conducting an air flow is formed. The fins each have at least one first through-opening through which the heat exchanger tube extends. At least some of the fins have a plurality of second through-openings, wherein a peripheral edge of the respective second through-opening forms a protuberance which protrudes from a surface of the respective fin facing an adjacent fin.

Description

TECHNICAL FIELD

[0001] The present invention relates to a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator, a freezer or a freezer chest or a fridge-freezer combination, and a heat exchanger for a refrigeration appliance. STATE OF THE ART

[0002] In household refrigerators, heat is extracted from a storage compartment in which refrigerated goods are stored by means of a refrigerant circuit by evaporating refrigerant in an evaporator and then released into the environment by condensing the refrigerant in a condenser.

[0003] Heat exchangers used as evaporators, and occasionally also as condensers, typically comprise a heat exchanger tube and a plurality of fins. The heat exchanger tube serves to conduct the refrigerant. The fins are connected to the heat exchanger tube in a heat-conducting manner and are typically arranged parallel to one another, leaving a gap between adjacent fins. A fan can generate an airflow through the gap to achieve efficient, convective heat transfer at the fins. In so-called NoFrost refrigeration units, the fan circulates an airflow between an evaporator chamber, in which the heat exchanger is located, and the storage compartment.

[0004] TR 2015 / 08021 describes a refrigeration appliance with a NoFrost evaporator. SUMMARY OF THE INVENTION

[0005] It is one of the objects of the present invention to provide improved solutions for heat exchangers of refrigeration devices, in particular solutions with which heat transfer at the fins of the heat exchanger can be further improved.

[0006] This object is achieved according to the invention by a heat exchanger having the features of claim 1 and by a refrigeration device having the features of claim 13. Advantageous embodiments and further developments emerge from the subclaims referring back to the independent claims in conjunction with the description.

[0007] According to a first aspect of the invention, a heat exchanger for a refrigeration appliance comprises a heat exchanger tube for conducting refrigerant and a plurality of fins which are arranged spaced apart from one another in a first direction, such that between two fins adjacent in the first direction, a flow channel extending in a second direction for conducting an air flow is formed. The fins each have at least one first through-opening through which the heat exchanger tube extends. At least some of the fins have a plurality of second through-openings, wherein a peripheral edge of the respective second through-opening forms a protuberance which protrudes from a surface of the respective fin facing an adjacent fin.

[0008] According to a second aspect of the invention, a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator, a freezer or a chest freezer, or a fridge-freezer combination, comprises a storage compartment for accommodating refrigerated goods and a refrigerant circuit designed to extract heat from the storage compartment by evaporating refrigerant and to release it to the environment by condensing refrigerant, wherein the refrigerant circuit has a heat exchanger according to the first aspect of the invention. Furthermore, the refrigeration appliance comprises a fan arranged and designed to transport an air flow through the flow channels of the heat exchanger.

[0009] One idea underlying the invention is to provide the fins of the heat exchanger with a plurality of second through-openings, in addition to the first through-openings through which the heat exchanger tube extends, whose peripheral edge forms a protrusion or at least a projection on one of the surfaces of the respective fin. The protrusion is thus part of a border of the second through-opening and protrudes from a surface of the respective fin in the first direction along which the fins are spaced from one another.

[0010] According to the invention, the protrusion formed by the peripheral edge of the respective second through-opening thus protrudes into the flow channel formed between two adjacent fins. As a result, an air flow flowing along the surface of the fin is swirled at the protrusions, which promotes the formation of a turbulent boundary layer. A turbulent boundary layer is thinner than a laminar boundary layer, which increases the average flow velocity in the flow channel. The turbulent boundary layer thus contributes to improving heat transfer at the fins.

[0011] The protrusions as part of the peripheral edge of a through-hole can be used to generate turbulence in the air flow particularly effectively, which promotes the formation of a turbulent boundary layer.

[0012] Because heat transfer at the fins is improved, the heat exchanger can be realized with a smaller heat transfer surface for a given heat transfer capacity. This allows for a more compact heat exchanger. At the same time, the length of the flow channel is shortened, which advantageously reduces any pressure loss in the air flow that may result from the provision of the protuberances.

[0013] According to some embodiments, the protrusion can be divided into several sections that are at least partially separated from one another. The border of the second through-opening can thus have several separate, for example, jagged sections, each of which protrudes from the surface of the slat. This further promotes the turbulence of the air flow.

[0014] According to some embodiments, the sections of the protrusion can be separated from each other by a notch. The notch thus ensures a regional separation of the individual sections.

[0015] According to some embodiments, the sections can be triangular or substantially triangular. The edges delimiting a section, together with a transition from the surface of the slat to the section, can thus define a triangular shape. "Substantially triangular" can also include a flattened or rounded tip of the triangle. Generally, the edges of the section converge. A free end of the section is thus pointed or nearly pointed, thus ensuring extremely efficient turbulence of the air flow.

[0016] According to some embodiments, it can be provided that the slats each have a first surface and a second surface oriented opposite thereto, wherein among the plurality of second through-openings, a first group of through-openings is provided, the peripheral edge of which forms a protrusion protruding from the first surface, and wherein among the plurality of second through-openings, a second group of through-openings is provided, the peripheral edge of which forms a protrusion protruding from the second surface. For example, through-openings of the first and second groups can be arranged alternately along the second direction and / or along a third direction extending transversely to the first and second directions. Because protrusions protrude from both surfaces of the respective slat, the heat transfer can be easily improved on both surfaces of the slat.

[0017] According to some embodiments, the lamellae may each have a first surface and a second surface oriented opposite thereto, with the protrusions formed by the peripheral edges of the second through-openings protruding either from the first surface or from the second surface. Thus, it may also be provided that protrusions protrude only from one of the surfaces of the respective lamella.

[0018] According to some embodiments, it can be provided that the second through-openings have an inner diameter in a range between 0.5 mm and 3 mm, in particular in a range between 0.8 mm and 2 mm. For example, the diameter can be 1 mm or 1.5 mm. A circumferential shape of the second through-openings is not limited to a circular shape, but can also be oval, elongated, or polygonal. In the case of a non-circular design, the inner diameter can, for example, be a minimum diameter of the through-opening or a diameter that would result from a circular through-hole with the same surface area.

[0019] The inner surface or cross-sectional area defined by the second through-hole lies in a range between 0.1% and 5% of the inner surface defined by the first through-hole. The second through-holes are thus very small compared to the first through-hole.

[0020] According to some embodiments, the second through-openings can be arranged in a regular pattern distributed across the respective fins. For example, the second through-openings can be arranged in parallel rows at regular intervals. This facilitates the production of the second through-openings and advantageously ensures uniform heat transfer across the surface of the fins.

[0021] According to some embodiments, it can be provided that a distance between two directly adjacent second through-openings, measured from center to center of the second through-openings, lies in a range between 3 mm and 10 mm, in particular between 4 mm and 6 mm. The center of the respective second through-opening can be defined by its centroid.

[0022] According to some embodiments, it can be provided that the first through-opening is designed as an elongated hole.

[0023] According to some embodiments, the fins may each be made of a metal sheet. Due to the good thermal conductivity of metal sheets, heat transfer at the fins is further improved.

[0024] According to some embodiments, the second through-openings can be produced as punctures through the metal sheet, with any individual sections of the peripheral edge being sheared off from one another. To produce the second through-opening, the metal sheet can be pierced using a punch or the like, causing the sheet to tear in a direction parallel to the surface and the material to be bent by the punch. Thus, several sections are formed along the circumference of the through-opening. These sections also have relatively sharp edges, which further promotes the turbulence of the air flow.

[0025] According to some embodiments, the heat exchanger tube can comprise a plurality of linearly extending first tube sections, and each pair of first tube sections can be connected to one another by an arcuate second tube section, wherein the first tube sections extend along the first direction. The linear first tube sections thus extend transversely to the fins. For example, each pair of first tube sections can extend through a first through-hole designed as an elongated hole. This advantageously allows a relatively long heat exchanger tube to be installed within a small volume.

[0026] According to some embodiments, it can be provided that the heat exchanger forms an evaporator thermally coupled to the storage compartment.

[0027] According to some embodiments, the refrigeration appliance may have an evaporator chamber fluidically connected to the storage compartment, in which the heat exchanger is arranged. The fan is arranged and configured to circulate air between the evaporator chamber and the storage compartment. The refrigeration appliance may thus be a NoFrost refrigeration appliance.

[0028] The features and advantages disclosed herein in connection with one aspect of the invention are also disclosed for the other aspect and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention is explained below with reference to the figures of the drawings. The figures show: Fig. 1 a simplified, schematic sectional view of a refrigeration device according to an embodiment of the invention; Fig. 2 is a perspective view of a heat exchanger according to an embodiment of the invention; Fig. 3 a perspective view of two adjacent fins of the heat exchanger from Fig. 2; Fig. 4 a detailed view of a fin of a heat exchanger according to an embodiment of the invention; Fig. 5 a perspective view of a fin of the heat exchanger from Fig. 2 looking towards a first surface of the lamella; and Fig. 6 a perspective view of a fin of a heat exchanger according to a further embodiment of the invention, looking towards a second surface of the fin.

[0030] In the figures, the same reference symbols denote identical or functionally identical components, unless otherwise stated. DETAILED DESCRIPTION OF EMBODIMENTS

[0031] Fig. 1 shows an example of a refrigeration device 200 in the form of a refrigerator. The invention will be described below by way of example with reference to the Fig. 1, but is not limited thereto. For example, the invention can also be used in other household refrigeration appliances, such as a freezer or chest freezer or a refrigerator-freezer combination, or in refrigeration appliances in general.

[0032] As in Fig. As shown schematically in Figure 1, the refrigeration appliance 200 has a body 202, which defines a storage compartment 210 for accommodating refrigerated goods, such as food, beverages, medications, or the like. A machine compartment 212, separate from the storage compartment 210, can optionally also be defined at least partially by the body 202.

[0033] As in Fig. 1, the refrigeration device 200 has a refrigerant circuit 220 and a fan 230. The refrigerant circuit 220 comprises an evaporator 221, a compressor 222, a condenser 223, and a throttle element (not shown), e.g., in the form of a capillary line.

[0034] The evaporator 221 is thermally coupled to the storage compartment 210 to extract heat therefrom by evaporating refrigerant. For example, the evaporator 221, as shown in Fig. 1 purely by way of example and shown only schematically, can be arranged in an evaporator chamber 215 fluidly connected to the storage compartment 210, and the fan 230 can be arranged and configured to circulate air between the evaporator chamber 215 and the storage compartment 210. The fan 230 thus draws in warm air from the storage compartment 210, directs it through or over the evaporator 221, where the air transfers heat to the refrigerant located in the evaporator 221, and then expels the air back into the storage compartment 210.

[0035] The evaporator 221 is connected to a suction port of the compressor 222. The compressor 222 compresses the gaseous refrigerant coming from the evaporator 221 and feeds it to the condenser 223, which is connected to a pressure port of the compressor 222. In the condenser 223, the refrigerant condenses, releasing heat to the environment. The condenser 223 is connected to the evaporator 221, with the throttle element (not shown) arranged between the condenser 223 and the evaporator 221 and expanding the refrigerant. As shown in Fig. 1 purely schematically, the compressor 222 can be arranged, for example, in the machine room 212. The condenser 223 is in Fig. 1 is also shown purely schematically and can be arranged, for example, on an outer wall of the body 202 or in the machine room 212.

[0036] The refrigerant circuit 220 is generally designed to extract heat from the storage compartment 210 by evaporating refrigerant and to release this heat to the environment by condensing refrigerant.

[0037] The evaporator 221 and the condenser 223 each form heat exchangers for transferring heat between the refrigerant and an air flow or ambient air. This is particularly true when the heat exchanger is actively exposed to an air flow, e.g., by means of a fan 230, as in the example of Fig. 1 is the case for the evaporator 221, it is desirable that an effective heat transfer takes place at the heat exchanger in order to be able to design the heat exchanger as compactly as possible.

[0038] Fig. 2 shows an example of a heat exchanger 100 for a refrigeration device 200. The Fig. The heat exchanger shown in Figure 2 can be used in the Fig. 1, for example, as an evaporator 221. However, the invention is not limited thereto.

[0039] As in Fig. 2, the heat exchanger 100 has a heat exchanger tube 1 for passing refrigerant and a plurality of fins 2.

[0040] The heat exchanger tube 1 can be meandering. As in Fig. 2, the heat exchanger tube 1 can have a plurality of linearly extending first tube sections 11 that extend along the first direction X. The first tube sections 11 can, for example, run parallel or substantially parallel. Furthermore, the heat exchanger tube 1 has curved second tube sections 12, wherein each two first tube sections 11 are connected to one another by a curved second tube section 12.

[0041] The slats 2 are generally realized as flat components and have a first surface 2a and a second surface 2b opposite thereto. As shown in Fig. 2, the slats 2 can, for example, have a rectangular circumference. The slats 2 have a small thickness, measured between the first and second surfaces 2a, 2b, which can, for example, be in a range between 0.1 mm and 0.3 mm. The slats 2 can, for example, be made of a metal sheet.

[0042] As particularly in the Fig. As can be seen in Figures 3 to 6, the slats 2 have first through-openings 21, which can be designed, for example, as elongated holes as shown. Furthermore, at least some, and optionally all, of the slats 2 have second through-openings 22 in addition to the first through-openings 21. The second through-openings 22 are explained in more detail below.

[0043] As in Fig. 2, the slats 2 are arranged spaced apart from one another in the first direction X. For example, the slats 2 can be arranged parallel to one another. In general, the first surface 2a of a slat 2 faces the second surface 2b of an immediately adjacent slat 2. Thus, between two slats 2 adjacent in the first direction X, a flow channel extending in a second direction Y for conducting an air flow is formed. The second direction Y extends transversely to the first direction X. As shown in Fig. 2, the flow channel additionally extends in the third direction Z, which runs transversely to the first and second directions X, Y.

[0044] As in Fig. As further shown in Figure 2, the heat exchanger tube 1 extends through the first through-openings 21 of the fins 21. For example, it can be provided that two linear, first sections 11 of the heat exchanger tube 1 each extend through a through-opening 21. Independently of this, the heat exchanger tube 1 is in thermally conductive contact with the fins 2, e.g., by resting against the inner circumference of the respective first through-openings 21.

[0045] The second through openings 22 are shown in detail in Fig. 4. As shown in Fig. As shown in Figure 4, a peripheral edge 23 of the second through-opening 22 forms a protrusion 3, similar to a collar. The protrusion 3 protrudes from the first or second surface 2a, 2b of the fin 2. Thus, a projection is formed on the edge of the second through-opening 22 on the respective surface 2a, 2b of the fin 2. When air flows along the respective surface 2a, 2b of the fin 2, the air is swirled at the protrusion 3. This effect is further enhanced by the fact that the protrusion 3 is formed by the peripheral edge 23 of the through-opening 22, which extends between the first and second surfaces 2a, 2b. Thus, the formation of a turbulent boundary layer is promoted, which improves heat transfer at the fins.

[0046] As in Fig. 4, the protuberance 3 can be divided into several sections 30 which are separated from each other at least in some areas. As shown in Fig. 4 purely by way of example, the sections 30 can be triangular or substantially triangular. The sections 30 are generally individual structures extending along the circumference of the second through-opening 23 and protruding from the respective surface 2a, 2b. As shown in Fig. As shown in Figure 4, the sections 30 can each be separated from one another by a notch 31. The second through-openings 22 can, for example, be made as punctures through the metal sheet of the slat 2.

[0047] When a punch or similar punching tool is used to pierce the lamella 2, the material of the lamella 2 tears locally, and the material is bent or folded by the tool. This forms individual, sheared-off pieces 30.

[0048] As in the Fig. 3 and Fig. 5, it can be provided that some of the protrusions 3 protrude from the first surface 2a of the respective lamella 2 and some of the protrusions 3 protrude from the second surface 2a of the respective lamella 2. A lamella 2 can thus have protrusions 3 on both of its surfaces 2a, 2b. For example, second through-openings 22 can be provided alternately along the second direction Y and / or along the third direction Z, the peripheral edge 23 of which forms a protrusion 3 alternately on the first and second surfaces 2a, 2b. In general, among the plurality of second through-openings 22, a first group of through-openings 22, the peripheral edge (23) of which forms a protrusion 3 protruding from the first surface 2a, and a second group of through-openings 22 can be provided, the peripheral edge 23 of which forms a protrusion 3 protruding from the second surface 2b.

[0049] Alternatively, it can be provided that the protrusions 3 formed by the peripheral edges 23 of the second through-openings 22 protrude either from the first surface 2a or from the second surface 2b. For example, in Fig. 6 shows a fin 2 in which the protrusions 3 formed by the peripheral edges 23 of the second through-openings 22 all protrude from the second surface 2b. In a heat exchanger 100, all fins 2 can be of the same design, or different fin configurations can be combined.

[0050] The second through-holes 22 have a smaller cross-sectional area than the first through-holes 21. For example, the cross-sectional area of ​​a second through-hole 22 can be in a range between 0.1% and 5% of a cross-sectional area of ​​a first through-hole 21.

[0051] An inner diameter of the second through-openings 22 can, for example, be in a range between 0.5 mm and 3 mm, in particular in a range between 0.8 mm and 2 mm. A distance between two directly adjacent second through-openings 22, measured from center to center of the second through-openings 22, can, for example, be in a range between 3 mm and 10 mm, in particular between 4 mm and 6 mm.

[0052] Regardless of the specific distance between them, the second through-openings 22 can be arranged in a regular pattern distributed over the respective slat 2. For example, as shown in the Fig. 3, Fig. 5 and Fig.6, the second through-openings 22 may be arranged in several parallel rows. The rows extend, for example, along the third direction Z and are spaced apart from one another in the second direction Y. The rows may be interrupted by the first through-holes 21.

[0053] Although the present invention has been explained above using exemplary embodiments, it is not limited thereto but can be modified in a variety of ways. In particular, combinations of the above embodiments are also conceivable. REFERENCE SYMBOL 1 heat exchanger tube 2 slats 2a first surface of the lamella 2b second surface of the lamella 3 protrusion 10 first pipe sections 11 second pipe sections 20 flow channels 21 first passage openings 22 second passage openings 23 Peripheral edge of the second through opening 30 pieces 31 notches 100 heat exchangers 200 refrigeration unit 202 Corpus 210 storage compartment 212 Engine room 215 Evaporator chamber 220 refrigerant circuit 221 evaporator 222 compressors 223 Condenser 230 fans X first direction Y second direction Z third direction QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] TR 2015 / 08021

[0004]

Claims

[1] Heat exchanger (100) for a refrigeration appliance (200), in particular for a household refrigeration appliance, comprising: a heat exchanger tube (1) for passing refrigerant; and a plurality of slats (2) which are arranged spaced apart from one another in a first direction (X), so that between two slats (2) adjacent in the first direction (X) a flow channel (20) extending in a second direction (Y) is formed for passing an air flow, wherein the slats (2) each have at least one first through-opening (21), through which the heat exchanger tube (1) extends; characterized by , that at least some of the slats (2) have a plurality of second through-openings (22), wherein a peripheral edge (23) of the respective second through-opening (22) forms a protuberance (3) which projects from a surface (2a, 2b) of the respective slat (2) facing an adjacent slat (2). [2] Heat exchanger (100) according to claim 1, wherein the protuberance (3) is divided into several sections (30) which are at least partially separated from one another. [3] Heat exchanger (100) according to claim 2, wherein the sections (30) are each separated from one another by a notch (31). [4] Heat exchanger (100) according to claim 2 or 3, wherein the sections (30) are triangular or substantially triangular. [5] Heat exchanger (100) according to one of the preceding claims, wherein the fins (2) each have a first surface (2a) and a second surface (2b) oriented opposite thereto, wherein among the plurality of second through-openings (22) a first group of through-openings (22) is provided, the peripheral edge (23) of which forms a protuberance (3) projecting from the first surface (2a), and wherein among the plurality of second through-openings (22) a second group of through-openings (22) is provided, the peripheral edge (23) of which forms a protuberance (3) projecting from the second surface (2b). [6] Heat exchanger (100) according to one of claims 1 to 4, wherein the fins (2) each have a first surface (2a) and a second surface (2b) oriented opposite thereto, and wherein the protuberances (3) formed by the peripheral edges (23) of the second through-openings (22) protrude either from the first surface (2a) or from the second surface (2b). [7] Heat exchanger (100) according to one of the preceding claims, wherein the second through-openings (22) have an inner diameter in a range between 0.5 mm and 3 mm, in particular in a range between 0.8 mm and 2 mm. [8] Heat exchanger (100) according to one of the preceding claims, wherein the second through-openings (22) are arranged in a regular pattern distributed over the respective fin (2). [9] Heat exchanger (100) according to one of the preceding claims, wherein a distance between two immediately adjacent second through-openings (22) measured from center to center of the second through-openings (22) is in a range between 3 mm and 10 mm, in particular between 4 mm and 6 mm. [10] Heat exchanger (100) according to one of the preceding claims, wherein the fins (2) are each made of a metal sheet. [11] Heat exchanger (100) according to claim 10 when dependent on claim 2, wherein the second through-openings (22) are made as punctures through the metal sheet, and wherein the sections (30) are sheared off from one another. [12] Heat exchanger (100) according to one of the preceding claims, wherein the heat exchanger tube (1) has a plurality of linearly extending first tube sections (11), and two first tube sections (11) are connected to one another by an arcuate second tube section (12), and wherein the first tube sections (11) extend along the first direction (X). [13] Refrigeration appliance (200), in particular household refrigeration appliance, comprising: a storage compartment (210) for holding refrigerated goods; a refrigerant circuit (220) which is designed to extract heat from the storage compartment (210) by evaporating refrigerant and to release it to the environment by condensing refrigerant, wherein the refrigerant circuit (220) has a heat exchanger (100) according to one of the preceding claims; and a fan (230) arranged and designed to transport an air flow through the flow channels (20) of the heat exchanger (100). [14] Refrigeration device (200) according to claim 13, wherein the heat exchanger (100) forms an evaporator (221) thermally coupled to the storage compartment (210). [15] Refrigeration device (200) according to claim 14, additionally comprising: an evaporator chamber (215) fluidically connected to the storage compartment (210), in which the heat exchanger (100) is arranged; wherein the fan (230) is arranged and configured to circulate air between the evaporator chamber (215) and the storage compartment (210).

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