Patent Publication Number: US-7219716-B2

Title: Heat exchanger

Description:
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 10-2003-0063677 filed in KOREA on Sep. 15, 2003, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a heat exchanger, and more particularly, to a heat exchanger that is designed to effectively guide air flowing along fins disposed between tubes up to rear ends of the tubes. 
   2. Description of the Related Art 
   Generally, a heat exchanger is installed in an air conditioner and functions as an evaporator or a condenser for performing a heat exchange between a refrigerant and air. A fin-tube type heat exchanger is widely used among various kinds of the heat exchanger. 
   In the fin-tube type heat exchanger, the fins installed in a tube for air flow are classified into a slit fin, a louver fin, and a corrugate fin that is formed in a W-shape. 
     FIG. 1  shows a conventional heat exchanger having the corrugate fin. 
   Referring to  FIG. 1 , a heat exchanger  1  includes a plurality of corrugate fins  10  spaced away from each other at a predetermined distance and formed in a W-shape, and a plurality of tubes  30  disposed penetrating the corrugate fins  10  at right angles and along which a refrigerant flows. 
   Here the fin  10  is provided with peak portions  12  and valley portions  14  at which the tubes are not penetrated and which are intersected with each other at a predetermined angle, a plurality of fin collars  16  defining tube insertion holes through which the tubes are inserted, and a plurality of seats  18  formed in a concentric circle shape to support the fin collars  16 . 
   Herein, the conventional heat exchanger having the corrugate fin will be described with reference to  FIGS. 1 to 4 . 
   Referring to  FIG. 1 , the heat exchanger  1  is a fin-tube type, and a plurality of fins  10  and a plurality of tubes are intersected with each other in a perpendicular direction. The tubes  30  arranged in two rows penetrate the plurality of fins  10  in a perpendicular direction. 
   Each of the fins  10  is the corrugate fin (hereinafter, abbreviated a fin). Each of the fins  10  has a plurality of donut-shaped flat portions and a plurality of inclined portions that are defined by the W-shape having a plurality of the peak and valley portions. The fins  10  are installed on the tubes  30  in a longitudinal direction of the tubes  30 , being spaced away from each other at a predetermined distance. 
   Referring to  FIGS. 2 and 3 , there is shown a detailed structure of the fin  10 . The fin  10  is formed in a W-shape with the peak and valley portions  12  and  14  that are alternately formed. That is, the fin  10  has two side ends that are respectively defined by the valley portions  14   a  and  14   c . In case a plurality of fins  10  are used, the tubes  30  are arranged in two rows in a zigzag-shape in order to improve a heat exchange efficiency. 
   That is, each of the fins  10  installed on the tube  30  has two peak portions  12   a  and  12   b  and three valley portions  14   a ,  14   b  and  14   c , which are alternately disposed and connected by inclined surfaces. The shape of the fin  10  is symmetrical based on the longitudinal valley portion  14   b . Central axes of the zigzag-shaped tube  30  pass through the longitudinal center valley portion  14   b.    
   The fin  10  is provided with a plurality of tube insertion holes  16   a , central axes of which correspond to the respective central axes of the zigzag-shaped tube  30 . The fin collars  16  are elevated from the fin  10  to define the tube insertion holes  16   a  through which the zigzag-shaped tube  30  is inserted. The tube  30  surface-contacts an inner circumference of each collars  16 . 
   The seat  18  is formed in a concentric circle shape around a lower end of an outer circumference of the fin collar  16  to support the fin collar  16  and to allow air to flow in the form of enclosing the tube  30  and the fin collar  16 . 
   An inclined portion  20  is formed on the fin  20  around the seat  18  to prevent the air flowing around the tube  30  from getting out of a circumference of the tube  30 . The inclined portion  20  is inclined upward from the seat  18  to the adjacent peak portions  12 . 
   The seat  18  is located on a horizontal level identical to that where the valley portions  14  are located. Heights and depths H 1  and H 2  of the peak and valley portions  12  and  14  are identical to each other. That is, the H 1  indicates the heights of the adjacent peak portion  12  from the valley portions  14 , and the H 2  indicates the depths of the adjacent valley portion  14  from the peak portion  12 . In addition, the inclined surfaces connecting the valley portions to the peak portions are inclined at an identical angle (θ). 
     FIGS. 4(   a ) and  4 ( b ) are respectively front and rear views of the fin, in which the peak portions  12  and valley portions  14  depicted in  FIG. 4(   a ) correspond to the valley portions  14  and peak portions  12  depicted in  FIG. 4(   b ), respectively. 
   When the air is introduced into the heat exchanger  1 , the growth of a frost formed on an outer surface of the fin  10  is proportional to an amount of a heat transfer on the outer surface of the fin  10 . At this point, the air flow speed is increased at the tube area as well as at the fin areas between the tubes  30  disposed in a longitudinal direction, thereby forming a high-speed air flow. As a result, the heat transfer coefficient is increased and the frost layer is quickly grown on the surface of the fin  10 . 
   In case the frost layer is grown on the surface of the fin  10 , since the distance between the adjacent fins  10  is reduced, an air passage area is also reduced. Due to the reduced area, the air flow speed is increased much more. As a result, the pressure drop of the air is increased in a parabola shape as time passes. Further, the heat transfer amount of the heat exchanger is also greatly reduced. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to a heat exchanger that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
   A first object of the present invention is to provide a heat exchanger that can improve the heat discharge efficiency by designing a corrugate fin such that heights between peak portions and valley portions that are formed on a left or right side of a reference line of a fin center portion through which central axes of the tube perpendicularly passes become different from one another. 
   A second object of the present invention is to provide a heat exchanger including a fin bent in a zigzag-shape such that heights and depths of outer peak and valley portions are greater than those of inner peak and valley portions. 
   A third object of the present invention is to provide a heat exchanger including a fin bent in a zigzag-shape such that heights of outer peak portions are greater than those of inner peak portions to increase a speed of air flowing along the fin between tubes. 
   A fourth object of the present invention is to provide a heat exchanger including a fin where an inner angle of a center peak portion is greater than that of an outer peak portion. 
   Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
   To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a heat exchanger including a plurality of tubes through which refrigerants flow, the tubes being spaced away from one another; and a fin through which the tubes are perpendicularly inserted, and having a fin collar for supporting the inserted tube, a seat for supporting an outer circumference of a lower end of the fin collar, and three or more peak portions and three or more valley portions that are alternately disposed at an area defined between the tubes to cause air flow to vary at an area defined between the fin collar, heights of at least two peak portions or depths at least two valley portions being different from each other. 
   According to another aspect of the present invention, there is provided a heat exchanger including a plurality of tubes through which refrigerants flow, the tubes being spaced away from one another; and a plurality of fins spaced away from one another at a predetermined distance, and each of the fin including a fin collar through which tube is perpendicularly inserted, and peak portions where a height of an inner horizontal plane is lower than a height of an outer horizontal plane and valley portions alternately disposed and inclined to cause an air flow direction to vary at an area defined between the fin collar. 
   It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the present invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
       FIG. 1  is a perspective view of a conventional heat exchanger; 
       FIG. 2  is a perspective view of a fin depicted in  FIG. 1 ; 
       FIG. 3  is a sectional view taken along the line A–A′ of  FIG. 2 ; 
       FIG. 4   a  is a front view of the fin depicted in  FIG. 2 ; 
       FIG. 4   b  is a rear view of the fin depicted in  FIG. 2 ; 
       FIG. 5  is a perspective view of a heat exchanger according to a preferred embodiment of the present invention; 
       FIG. 6  is a perspective view of the fin depicted in  FIG. 5 ; 
       FIG. 7  is a sectional view taken along the line B–B′ of  FIG. 6 ; 
       FIG. 8   a  is a front view of the fin depicted in  FIG. 6 ; 
       FIG. 8   b  is a rear view of the fin depicted in  FIG. 6 ; 
       FIG. 9  are views illustrating modified examples similar to that depicted in  FIG. 7 ; and 
       FIGS. 10 and 11  are views illustrating air flow states in a heat exchanger according to a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     FIGS. 5 to 11  show a preferred embodiment of the present invention. 
   Referring first to  FIGS. 5 to 7 , the inventive heat exchanger  101  includes a plurality of fins  110  spaced away from one another at a predetermined distance and a plurality of tubes  130 , along which a refrigerant flows, disposed penetrating the fins  110  at right angles. 
   The fin  110  is formed in an inversed W-shape. That is, the fin  110  includes first, second and third peak portions  112  ( 112   a ,  112   b  and  112   c ), first, second, third and fourth valley portions  114  ( 114   a ,  114   b ,  114   c  and  114   d ), fin collars  116  formed defining tube insertion holes  116   a  through which the tubes  130  perpendicularly pass, seats  118  for supporting outer circumference surfaces of lower ends of the fin collars  116 , and inclined portions  120  inclined upwardly from outer circumferences of the seats  118  to the peak portions  112 . 
   The peak portions  112  and the valley portions  114  are alternately formed between the fin collars  116  and are connected to one another by surfaces inclined at predetermined inclination angles θ 1  and θ 2  that are different from each other. 
   For variation of air flow, a height (H 12 ) of the second peak portions  112   b  can be designed to be lower than heights (H 11 ) of the first and third peak portions  112   a  and  112   c , or contrarily the heights (H 11 ) of the first and third peak portions  112   a  and  112   c  can be designed to be higher than the height (H 12 ) of the second peak portions  112   b . Due to undulated elements for air flow variation, the air flowing between the tubes can be more effectively guided up to rear ends of the tubes  30 . 
   The operational effect of the heat exchanger according to the preferred embodiment of the present invention will be described hereinafter. 
   As shown in  FIGS. 5 to 8 , the heat exchanger  301  is a fin-tube type in which a plurality of corrugate fins each formed in a W-shape are perpendicularly disposed with respect to the tubes  130  and are spaced away from one another at a predetermined distance. 
   Each of the fins  110  is divided into a fin collar area through which the tubes  130  penetrate and an inclined surface area defined between the fin collars  116 . The heights and depths of the peak portions and valley portions are different from each other to let the flow of the air introduced into the heat exchanger changed. 
   That is, inclined angles θ 1  and θ 2  of the inclined surfaces connecting the alternately disposed peak portions  112  and valley portions  114  are different from each other. For the more effective air incoming and outgoing operation, the fin  110  is designed having both side ends defined by the first and fourth valley portions  114   a  and  114   d . That is, the fin  110  starts with the valley portion  114   a  and ends with the valley portion  114   d  in a lateral direction. 
   In addition, the fin  110  is designed to be symmetrical based on the center peak portion  112   b . That is, the left and right portions based on the central peak portion  112   b  are symmetrical, and the heights and depths of the peak portions and valley portions formed on each of the left and right portions are different from each other. 
   As shown in  FIG. 7 , the valley portions  114   a – 114   d  are located on an identical horizontal plane, and the peak portions  112   a – 112   d  are located on a different horizontal plane. 
   The first peak portion  112   a  is connected to the surfaces  113   a  and  113   b  inclined at the predetermined angle θ 1  between the first valley portion  114   a  with which the fin starts and the second valley portion  114   b . The second peak portion  112   b  is connected at the different angle θ 2  to the inclined surfaces  113   c  and  113   d  between the second valley portion  114   b  and the third valley portion  114   c . The third peak portion  112   c  is connected at the different angle θ 1  to the inclined surfaces  113   e  and  113   f  between the third valley portion  114   c  and the fourth valley portion  114   d  with which the fin ends. 
   At this point, the height of the inner peak portion  112   b  is designed to be different from heights of the outer peak portions  112   a  and  112   c.    
   That is, as shown in  FIGS. 6 and 7 , the valley portions  114  are located on the identical horizontal plane, and the peak portions  112  are located having different heights H 11  and H 12 . That is, the height H 12  of the center peak portion  112   b  is formed to be lower than the heights H 11  of the outer peak portions  112   a  and  112   c.    
   Herein, the left and right portions based on the center peak portion  112   b  are symmetrical, and the heights of the peak portions  112   a  and  112   c  and the depths of the valley portions ( 114   a ,  114   b ) and ( 114   c ,  114   d ) formed on each of the left and right portions are different from each other. 
   For example, the height H 12  from the horizontal plane where the inner peak portions  112   b  is located to the inner peak portions  114   b  and  114   c  is designed to be lower than the depths H 11  from the horizontal plane to the outer valley portions  114   a  and  114   d.    
   That is, the heights H 11  of the first and third peak portions  112   a  and  112   c  are the same as each other, and the height H 12  of the second peak portion  112   b  is different from the height H 11 . Accordingly, the height H 12  of the second peak portion  112   b  is formed to be lower than the heights of the first and third peak portions  112   a  and  114   c.    
   By the above-described structure, the air flow of the air introduced into areas defined between the fins  110  is varied due to the fin structure where the inner peak portion  112   b  is lower than the outer peak portions  112   a  and  112   c . That is, the air flow of the air introduced into and then escaped from areas defined between the fins  110  is greatly varied when compared with the conventional art Therefore, the air can be more effectively guided up to the rear ends of the tubes  30 . In addition, the pressure drop is reduced for the high-speed air flow and an amount of the heat transfer is increased. 
   In more detail, when the heights H 11  from the horizontal plane where the first valley portion  114   a  is located to the first and third peak portions  112   a  and  112   c  are the same as each other, the height H 12  from the horizontal plane where the first valley portion  114   a  is located to the second peak portion  112   b  is lower than the heights H 11  of the first and third peak portions  112   a  and  112   c.    
   Meanwhile, the fin collars  116  are spaced away at a predetermined distance in a longitudinal direction of the fin  110  and are penetrated by each of the tubes  130 . The fin collars  116  define tube insertion holes  116   a  each having a diameter corresponding to an outer diameter of the tube to support the tube  130  inserted therein. 
   In addition, the seat  118  formed around a lower end of an outer circumference of the fin collar  116  has a predetermined width to support the fin collar  116 . The seat  118  is disposed on a horizontal plane identical to that where the second and third valley portions  114   b  and  114   c  are located. 
   The inclined portions  120  inclined upwardly from outer circumferences of the seat to the peak portions  112 . That is, each of the inclined portions  120  is defined by connecting each of the peak portion  112   a  to the valley portions  114   b  and  114   c  contacting the outer circumference of the seat  118  and adjacent to the peak portions  112   a , thereby being formed in a triangular-shape. The inclined portions  120  guide the air to flow along the outer circumference of the fin collars  116 . 
   In addition, the inclined portions  120  may be further formed by connecting two points of each outer peak portion (the first and third peak portions  112   a  and  112   c ) to two points of each inner adjacent valley (the second and third valleys  114   b  and  114   c ) contacting the seat  118 . In this case, the inclined portions  120  are formed in a rectangular-shape. 
   The inclined portions  120  respectively function as a wall enclosing the fin collar  116 . 
   In the above-described present invention, the height H 12  from the horizontal plane where the valley portion  114  is located to the inner peak portion  112   b  should be lower than the heights H 11  of the outer peak portions  112   a  and  112   c . For example, one or more inner peak portions should be lower than the outer peak portion in height. 
     FIGS. 8   a  and  8   b  respectively show front and rear views of the fin according to the preferred embodiment of the present invention. 
   The peak portions and the valley portions that are depicted in  FIG. 8   a  become the valley portions and the peak portions in  FIG. 8   b , respectively. That is, when being viewed in  FIG. 8   b , the depths from the horizontal plane where the peak portions are located to the valley portions are different from one another. 
     FIG. 9  shows a modified example of the preferred embodiment. 
   In this modified example, first, second, third and fourth peak portions  152  ( 152   a ,  152   b  and  152   c ) are located on an identical horizontal plane. The depth H 13  from the horizontal plane where the peak portion  152  is located to the inner valley portions  154   b  and  154   c  is lowered than the depths of the outer valley portions  154   a  and  154   b . That is, H 11 ′ is higher than H 13 . Further, an inner angle θ 1 ′ of the first peak portion  152   a  is smaller than an inner angle θ 2 ′. 
   Accordingly, the present invention has an effect in that a pressure drop is reduced and the heat transfer amount is increased relatively when H 11  does not equal to H 12  and H 11 ′ does not equal to H 13  compared with when H 11  does equal to H 12 . 
   For example, an inclination structure can be formed where a specific valley portion or peak portion is located on the same horizontal plane, and the heights from the same horizontal planes to the peak portion or the valley portion are gradually lowered going into the areas defined between the fins, and gradually increased going from the areas defined between the fins. 
   In the above-described preferred embodiment, since the peak or valley portions are designed having a different height or depth, a contacting area with the air is increased, increasing the air flow variation. 
     FIGS. 10 and 11  show an air flow state of the heat exchanger according to the preferred embodiment.  FIG. 10  is a case where the fin is formed of a single fin structure, and  FIG. 11  is a case where the fin is formed of a dual fin structure. 
   As shown in  FIG. 10 , when outer air is introduced into the heat exchanger, since the air quickly flows between the tubes while it repeatedly ascends and descends along the peak and valley portions  112  and  114 , the contacting area between the air and the fins is increased. 
   That is, the air is introduced through the first valley portion  114   a  and the second peak portion  112   a . The flow of the air introduced through the first peak portions  112   a  is varied as it further flows along the inner valley portions  114   b  and  114   c , and peak portion  112   b . As a result, the air flow speed is increased such that the air flow is sent to the peak portion  112   c  and the valley portion  114   d  at an outlet side, thereby increasing the heat transfer efficiency. 
   Furthermore, since the heights H 11  of the first and third peak portions  112   a  and  112   c  that are located on inlet and outlet sides of the air, respectively, are higher than those H 12  of the second peak portion  112   b , the distance between the adjacent fins  110  is increased to thereby increase the air passage area. As a result, the pressure drop is reduced for the high-speed air flow to thereby increase the amount of heat transfer and reduce the overall pressure drop of the heat exchanger. 
   In addition, since the fin collars, seats and inclined portions are formed around the tube insertion holes through which the tube is inserted, the air can be guided up to the rear end of the tube along the curvatures of the tube and the inclined portions. 
   In more detail, when the air passes between the tubes  130  with a high-speed, the high-speed air flow increases the heat transfer and retards the growth of the frost layer. Accordingly, a high level of heat capacity is maintained even under the frost forming condition, thereby increasing the heat exchange capability and making it possible to run the heat exchanger for a long term. 
     FIG. 11  shows an air flow state when the fins are formed in a dual fin structure and the tubes are perpendicularly installed on the fins in a zigzag-shape. Since the tubes are arranged in the zigzag-shape, when the air passes through a tube area and a none-tube area (area between the tubes), the air flow is realized as in the case where the fin is formed of a single fin plate. 
   In the above-described preferred embodiment, since the heights or depths of the inner peak and valley portions are lower than those of the outer peak and valley portions that are disposed on inlet and outlet sides of the air, the air can quickly flow between the tubes, the air can be effectively guided up to the rear end of the tube. In addition, since the pressure drop is reduced for the fast flow speed of the air flowing between the tubes while the heat transfer amount and heat exchange amount are increased, thereby improving the overall efficiency of the heat exchanger. 
   As described in the above embodiments, by varying the design of the fins, the overall heat transfer efficiency can be improved. 
   It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.