(19)
(11)EP 2 236 972 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
30.09.2020 Bulletin 2020/40

(21)Application number: 10003134.3

(22)Date of filing:  24.03.2010
(51)International Patent Classification (IPC): 
F28F 1/12(2006.01)
F28F 19/00(2006.01)

(54)

Fin for heat exchanger and heat exchanger using the fin

Lamelle für Wärmetauscher und Wärmetauscher mit einer solchen Lamelle

Ailette pour échangeur thermique et échangeur thermique utilisant l'ailette


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR

(30)Priority: 25.03.2009 CN 200910119662

(43)Date of publication of application:
06.10.2010 Bulletin 2010/40

(73)Proprietors:
  • Sanhua (Hangzhou) Micro Channel Heat Exchanger Co., Ltd.
    Zhejiang Province (CN)
  • Danfoss A/S
    6430 Nordborg (DK)

(72)Inventors:
  • Huazhao, Liu
    Hangzhou Zhejiang 310018 (CN)
  • Huang, Lin-jie
    East Amherst, NY 14051 (US)

(74)Representative: Keil & Schaafhausen Patentanwälte PartGmbB 
Friedrichstraße 2-6
60323 Frankfurt am Main
60323 Frankfurt am Main (DE)


(56)References cited: : 
JP-A- H08 178 366
US-A1- 2005 045 314
US-A1- 2007 240 865
US-A1- 2003 136 554
US-A1- 2005 077 036
US-A1- 2008 190 588
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Field of the invention



    [0001] The present invention relates to a heat exchanger, and more particularly to a fin used with a heat exchanger. JPH08178366 discloses a fin for a heat exchanger with the features of the preamble of claim 1.

    Background of the invention



    [0002] A heat exchanger is a commonly used component in refrigeration system and air conditioning system, and can be classified as a condenser, an evaporator and so on based on its functions. To improve the heat exchanging performance of a heat exchanger, among others, the heat exchanger is generally provided with a fin.

    [0003] Figs. 1A and 1B show a conventional fin used with a heat exchanger, Fig. 1A is a plan view of the fin, and Fig. 1B is a sectional view taken along line B-B in fig. 1A.

    [0004] A fin is made of a material with a high thermal conductivity such as aluminium alloy, and is formed by processing an aluminium alloy sheet. In the operation state of the heat exchanger, the fin contacts a surface of the heat exchanger, such as a surface of a flat tube, such that thermal conduction is achieved between the fin and the flat tube. And the fin conducts heat exchange with external medium flowing over the fin, and thus achieving the heat exchange between the heat exchanger and the external medium.

    [0005] As shown in figs.1A and 1B, the fin 1 is formed with louvers 20, the louvers can be divided into two sets-a leading set and a trailing set in the flowing direction of the medium such as air, which is in the left-right direction in fig. 1B. The louver pattern of the conventional fin is completely symmetrical, specifically, the louver gap and tilt angle of the leading set of louvers are identical with the louver gap and tilt angle of the trailing set of louvers. During the operation of the heat exchanger, the flowing air flows through the leading set of louvers first, and then the trailing set of louvers.

    [0006] When a microchannel heat exchanger is used in an outdoor unit of a heat pump, if the outdoor atmospheric temperature is low, frost will form on the external surface of the heat exchanger and on the fin. The frost forms faster and more on the leading set, while the frost forms slower and less on the trailing set. If the louver gap and tilt angle of the leading set are identical with the louver gap and tilt angle of the trailing set, since the frost forms faster and more on the leading set, the area of the gap between adjacent louvers of the leading set of the fin, through which the air flows, will decrease. As a result, the wind resistance increases at the leading set and the amount of air flowing through decreases, resulting in the degradation of the hear exchange performance of the heat exchanger. Thus, the heat exchange performance of the microchannel heat exchanger is not completely utilized.

    [0007] In consideration of the problems associated with the conventional fin, there is a need for further improving the heat exchange performance of the heat exchanger.

    Summary of the Invention



    [0008] The object of invention is to solve the problems associated with the conventional fin, and provides a fin for a heat exchanger which can improve the heat exchange performance of the heat exchanger, especially when frost forms on the fin.

    [0009] Another object of the invention is to provide a heat exchanger provided with a fin in accordance with the invention.

    [0010] To achieve the above objects, according to the invention, there is provided a fin for a heat exchanger, with the features of claim 1.

    [0011] According to a second aspect of the invention, there is provided a heat exchanger which comprises a fin as defined in the first aspect of the invention.

    [0012] Preferably, the heat exchanger is a microchannel heat exchanger.

    [0013] With the technical solution of the invention, the louver gap at a certain portion of the louvers is made to match with the amount of frost formed at that portion, such that a sufficient space is still left between adjacent louvers for the air to flow through. As a result, the wind resistance will not increase substantially to decrease the amount of air flowing through, and thus the heat exchange performance of the fin can be utilized completely.

    Brief description of the drawings



    [0014] The invention will be described in detail below with reference to the accompanying drawings, in which:

    Fig. 1A is a plan view showing the structure of a conventional fin used with a heat exchanger;

    Fig. 1B is a sectional view taken along line A-A in fig.lA, showing the pattern of conventional louvers;

    Fig. 2 is a view similar to fig.1B, showing the pattern of louvers not forming part of the invention;

    Fig. 3 is a view similar to fig.2, showing the pattern of louvers not forming part of the invention;

    Fig. 4 is a view similar to fig.2, showing the pattern of louvers not forming part of the invention; and

    Fig. 5 is a view similar to fig.3, showing the pattern of louvers in accordance with the invention.


    Detailed description of the preferred embodiments



    [0015] The fin used for a heat exchanger according to the invention will be described in detail below. It should be noted that the embodiments of the invention are only illustrative, they are only used to describe the principle of the invention but not to limit the invention. Furthermore, it is obvious to one skilled in the art that the fin according to the invention can be used with various heat exchangers which use a fin, including a microchannel heat exchanger.

    [0016] In the following description, components similar to those in the prior art will be designated with the same reference numerals and their detailed description will be omitted.

    [0017] The area between two adjacent louvers, through which air flows, depends on a distance between the two adjacent louvers measured in a line perpendicular to the two louvers, i.e. the louver gap. The present invention takes into consideration the difference of the frost-forming condition between the leading set and the trailing set of the louvers, and the difference of the frost-forming condition at different portions of the leading set and the trailing set in the air flow direction, and provides a louver pattern that can prevent the heat exchanging performance of a heat exchanger from degrading when frost forms on the fin.

    [0018] Reference is now made to fig. 2, which shows the pattern of louvers not forming part of the invention.

    [0019] The pitch of the louvers decreases gradually in the air flow direction, and the tilt angle of the louvers remains constant, such that the louver gap d of the louvers decreases gradually in the air flow direction, i.e. dl>d2>d3>d4>d5>d6>d7>d8, as schematically shown in fig.2.

    [0020] Fig.3 shows the fin not forming part of the invention

    [0021] The pitch between adjacent louvers in the leading set of the louvers is set to a first pitch, the pitch between the adjacent louvers in the trailing set of louvers is set to a second pitch which is smaller the first pitch, and the tilt angle of all the louvers remains constant, such that the leading set of louvers has a first uniform louver gap D1, and the trailing set of louvers has a second uniform louver gap D2, and the first louver gap D1 is larger than the second louver gap D2, as shown in fig. 3.

    [0022] Fig.4 shows the fin not forming part of the invention.

    [0023] The tilt angle α of the louvers is made to decrease gradually in the air flow direction, i.e. α1>α2>α3>α4>α5>α6>α7>α8 and the louver pitch between the adjacent louvers of the louvers remains constant, so that the louver gap between the adjacent louvers of the louvers decreases gradually, as shown in fig.4.

    [0024] Fig.4 shows the fin in accordance with the invention. In consideration of the fact that the amount of frost formed on the various portions of the louvers decreases gradually along the air flow direction, the fin in accordance with the invention adopts a solution as follows.

    [0025] The tilt angle of the louvers in the leading set of louvers is set to a first tilt angle α1, the angle of the louvers in the trailing set of louvers is set to a second tilt angle α2 which is smaller the first tilt angle α1, and a uniform pitch is provided between adjacent louvers, such that the leading set of louvers have a first uniform louver gap and the trailing set of louvers have a second uniform louver gap, and the first louver gap is larger than the second louver gap, as shown in fig. 5. With such a pattern, the louver gap of the leading set of louvers and the louver gap of the trailing set of louvers are made to match respectively with the amount of frost formed at the leading set and the trailing set: the frost forms more at the leading set of louvers, and accordingly the louver gap of the leading set of louvers is relatively large; and the frost forms less at the trailing set of louvers, and accordingly the louver gap of the trailing set of louvers is relatively small.

    [0026] With a louver pattern mentioned above, since the louver gap of the louvers is relatively large at the leading set of louvers where the frost forms more, and thus can accommodate more frost. Accordingly, even at the leading set of louvers where the frost forms more, enough space is still left between adjacent louvers for the air to flow through.

    [0027] With a fin in accordance with the invention, at the leading set, since the louvers have a relatively large tilt angle, and the density of the louvers does not decrease even if a large louver gap is provided, a good heat exchange performance is achieved. And furthermore, since a large louver gap is provided at the leading set, the amount of air flowing through will not be substantially decreased when frost forms, and thus the heat exchange performance of the fin is completely utilized. And furthermore, with the fin in accordance with the invention, since the leading set of louvers has a uniform tile angle and so does the trailing set of louvers, the fin can be relatively easily manufactured as compared with the fin of the third embodiment.

    [0028] It can be seen from above that, according to the invention, the louver gap between adjacent louvers at a certain portion of the louvers is made to match with the amount of frost formed there, such that a sufficient space is still left between any two adjacent louvers for the air to flow through when frost forms on the louvers. As a result, the wind resistance will not increase substantially to decrease the amount of air flowing through, thus the heat exchange performance of the fin is utilized completely.

    [0029] The invention have been described above in connection with the drawings. It should be appreciated by one skilled in the art that the embodiments are only exemplary but not limitative, various modifications are possible without departing from the scope of the invention.

    [0030] In the above embodiment, the louvers are divided into a leading set and a trailing set in the air flow direction, and each set has a uniform louver gap. However, the present invention is not limited to this, and various changes can be made based on the principle of the invention e.g.:
    1. 1. One or both of the leading set and trailing set can be further divided into several sub-sets in the air flow direction, and each sub-set has a uniform louver gap, the adjacent sub-sets have a different louver gap.
    2. 2. The louver gap of one of the leading set and the trailing set decreases gradually in the air flow direction.
    3. 3. One or both of the leading set and trailing set can be further divided into e.g. a first sub-set and a second sub-set in the air flow direction one of the first and second sub-sets has a uniform louver gap, and the other of the first and second sub-sets has a louver gap which decreases gradually in the air flow direction.


    [0031] And furthermore, for the sake of facilitating description, the louvers are divided into a leading set and a trailing set in the air flow direction in the above embodiments, but it is obvious to one skilled in the art that the louvers can be divided into a number of sets in the air flow direction in some other ways.


    Claims

    1. A fin (1) for a heat exchanger having an air flow direction for air, which is used as heat exchange medium when the heat exchanger operates, said fin being formed with louvers (20) arranged successively in the air flow direction,
    wherein said louvers are divided into a leading set which is located upstream and a trailing set which is located downstream in the air flow direction,
    wherein the leading set of louvers has a first uniform and constant louver gap, the trailing set of louvers has a second uniform and constant louver gap, and the first louver gap is larger than the second louver gap, wherein the tilt angle of the leading set is larger than the tilt angle of the trailing set, characterised in that said sets have a uniform pitch such that a louver gap at a certain portion of the louvers matches with a amount of frost formed at said portion.
     
    2. A heat exchanger which comprises a fin as claimed in claim 1.
     
    3. The heat exchanger as claimed in claim 2, wherein said heat exchanger is a microchannel heat exchanger.
     


    Ansprüche

    1. Rippe (1) für einen Wärmetauscher mit einer Luftströmungsrichtung für Luft, die beim Betrieb des Wärmetauschers als Wärmetauschmedium verwendet wird, wobei die Rippe mit in Luftströmungsrichtung hintereinander angeordneten Lamellen (20) ausgebildet ist, wobei die Lamellen in einen vorderen Satz, der sich stromaufwärts befindet, und einen hinteren Satz, der sich stromabwärts in Luftströmungsrichtung befindet, unterteilt sind, wobei der vordere Lamellensatz einen ersten gleichmäßigen und konstanten Lamellenspalt aufweist, der hintere Lamellensatz einen zweiten gleichmäßigen und konstanten Lamellenspalt aufweist und der erste Lamellenspalt größer als der zweite Lamellenspalt ist, wobei der Neigungswinkel des vorderen Satzes größer ist als der Neigungswinkel des hinteren Satzes, dadurch gekennzeichnet, dass die Sätze eine gleichmäßige Teilung haben, so dass ein Lamellenspalt an einem bestimmten Abschnitt der Lamellen mit einer an diesem Abschnitt gebildeten Frostmenge übereinstimmt.
     
    2. Wärmetauscher, der eine Rippe nach Anspruch 1 aufweist.
     
    3. Wärmetauscher nach Anspruch 2, wobei der Wärmetauscher ein Mikrokanal-Wärmetauscher ist.
     


    Revendications

    1. Ailette (1) pour échangeur thermique ayant une direction d'écoulement d'air pour de l'air, qui est utilisée en tant que support d'échange thermique lorsque l'échangeur thermique fonctionne, ladite ailette étant formée avec des évents (20) agencés successivement dans la direction d'écoulement d'air,
    dans lequel lesdits évents sont divisés en un jeu avant qui est situé en amont et un jeu arrière qui est situé en aval dans la direction d'écoulement d'air,
    dans lequel le jeu d'évents avant a un premier espace d'évents uniforme et constant, le jeu d'évents arrière a un second espace d'évents uniforme et constant, et le premier espace d'évents est plus grand que le second espace d'évents,
    dans lequel l'angle d'inclinaison du jeu avant est plus grand que l'angle d'inclinaison du jeu arrière, caractérisé en ce que lesdits jeux ont un pas uniforme de telle sorte qu'un espace d'évents à une certaine portion des évents correspond à une quantité de gel formé sur ladite portion.
     
    2. Échangeur thermique comportant une ailette selon la revendication 1.
     
    3. Échangeur thermique selon la revendication 2, dans lequel ledit échangeur thermique est un échangeur thermique à micro-canaux.
     




    Drawing