Patent Publication Number: US-2012031598-A1

Title: Plate heat exchanger

Description:
TECHNICAL FIELD 
     The present invention relates, in general, to a plate heat exchanger and, more particularly, to a plate heat exchanger which can increase the fluidity of a fluid, thereby realizing improved heat exchange efficiency. 
     BACKGROUND ART 
     A heat exchanger is a device for transferring heat from a higher temperature fluid to a lower temperature fluid through a heat transfer wall, and is used in an air conditioning system, a transmission oil cooler, etc. of an automobile. To be accommodated in a limited space in which the heat exchanger is installed, it is required to realize compactness of the heat exchanger and, accordingly, a plate heat exchanger has been widely used. 
     The plate heat exchanger includes a plurality of heat exchange elements that are stacked to define a flow channel between neighboring plates of the elements. The flow channel includes at least two flow channels through which different heat exchange medium can flow. In the plate heat exchanger, the different heat exchange medium exchange heat with each other through the heat exchange elements when the medium pass through the respective flow channels. Further, each of the respective plates of the heat exchange elements has an inlet port and an outlet port in opposite ends thereof, wherein the inlet ports and the outlet ports of the respective plates communicate with each other. An inlet cap and an outlet cap are mounted to the inlet and outlet ports of the uppermost plate by brazing, etc. 
     As shown in  FIG. 8 , a heat exchange element of a conventional plate heat exchanger is fabricated by assembling a pair of plates  1  and  2  with each other. Here, on the facing surfaces of the respective plates  1  and  2 , a plurality of diagonal grooves  1   a  and  2   a  are formed by embossing the plates  1  and  2  in such a way that the grooves  1   a  and  2   a  extend diagonally. When the plates  1  and  2  are assembled with each other, the grooves  1   a  and  2   a  form a flow channel. Further, opposite ends of the respective plates  1  and  2  are provided with respective through holes  1   b  and  2   b  for forming an inlet port and an outlet port. Depressed edges  1   c  and  2   c  are formed around the respective through holes  1   b  and  2   b.    
     During the operation of the plate heat exchanger, a fluid in the flow channel flows along the grooves  1   a  and  2   a  of the respective plates  1  and  2 , so that the fluid flows in an diagonal direction. Therefore, the flow of fluid may easily stagnate on the depressed edges  1   c  and  2   c  around the through holes  1   b  and  2   b , so that the conventional plate heat exchanger excessively reduces the fluidity of the fluid and, accordingly, reduces the heat exchange efficiency. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and is intended to provide a plate heat exchanger which can increase the fluidity of a fluid, thereby realizing improved heat exchange efficiency. 
     Technical Solution 
     In an aspect, the present invention provides a plate heat exchanger, including: 
     a plurality of heat exchange elements stacked in such a way that one is laid on top of another, each of the heat exchange elements being formed by assembling an upper plate and a lower plate, with a first flow channel defined in each of heat exchange elements and allowing a first fluid to pass therethrough, and a second flow channel defined between the heat exchange elements and allowing a second fluid to pass therethrough, further including: 
     an inlet port and an outlet port formed in opposite ends of each of the heat exchange elements, an upper flange formed on the upper plate by extending upwards from each of the inlet and outlet ports, a lower flange formed on the lower plate by extending downwards from each of the inlet and outlet ports, 
     a plurality of upper flow grooves diagonally extending on a lower surface of the upper plate, and a plurality of lower flow grooves diagonally extending on an upper surface of the lower plate, wherein the upper plate and the lower plate are assembled with each other in such a way that the upper flow grooves intersect with the lower flow grooves, thereby defining the first flow channel in each of the heat exchange elements, further including: 
     a flow guide structure for guiding the first fluid in at least two flow directions, the flow guide structure being provided on at least one of areas around the inlet and outlet ports of the upper plate and on at least one of areas around the inlet and outlet ports of the lower plate. 
     The upper flow grooves may extend to the areas around the upper flanges of the upper plate, with at least one upper subsidiary groove being formed in each of the upper flanges of the upper plate, wherein the at least one upper subsidiary groove intersects with the upper flow grooves. 
     The lower flow grooves may extend to the areas around the lower flanges of the lower plate, with at least one lower subsidiary groove being formed in each of the lower flanges of the lower plate, wherein the at least one lower subsidiary groove intersects with the lower flow grooves. 
     In the plate heat exchanger, at least one upper spacing lug may be formed on an upper surface of the upper plate, and at least one lower spacing lug may be formed on a lower surface of the lower plate. 
     The upper spacing lug of each of the heat exchange elements may be in contact with the lower spacing lug of a neighboring heat exchange element, the upper spacing lug and the lower spacing lug having respective through holes on contact surfaces thereof so that the first flow channels of the heat exchange elements communicate with each other. 
     Advantageous Effects 
     As described above, the plate heat exchanger according to the present invention uses a flow guide structure, by which the fluid can be guided in at least two flow directions in the area around the upper flange of the upper plate and/or around the lower flange of the lower plate, so that the present invention prevents stagnation of the fluid in the areas around the inlet ports and the outlet ports of the heat exchange elements and allows the fluid to smoothly and constantly flow for the whole length of the respective plates and, accordingly, increases the fluidity of the fluid and realizes improved heat exchange efficiency. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a plate heat exchanger according to an embodiment of the present invention; 
         FIG. 2  is a sectional view illustrating the axial cross-section of the plate heat exchanger according to the embodiment of the present invention; 
         FIG. 3  is an exploded perspective view illustrating upper and lower plates of a heat exchange element according to the present invention when the upper and lower plates are separated from each other; 
         FIG. 4  is an enlarged perspective view illustrating a portion designated by the arrow A in  FIG. 3 ; 
         FIG. 5  is a bottom view of the upper plate viewed in a direction designated by the arrow C in  FIG. 4 ; 
         FIG. 6  is an enlarged perspective view illustrating a portion designated by the arrow B in  FIG. 3 ; 
         FIG. 7  is a bottom view of the lower plate viewed in a direction designated by the arrow D in  FIG. 6 ; and 
         FIG. 8  is a view illustrating a heat exchange element of a conventional plate heat exchanger. 
     
    
    
     MODE FOR INVENTION 
     Hereinbelow, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
       FIGS. 1 through 7  show a plate heat exchanger according to an embodiment of the present invention. 
     As shown in  FIG. 1 , the plate heat exchanger of the present invention includes a plurality of heat exchange elements  10 , wherein the plurality of heat exchange elements is stacked in such a way that one is laid on top of another. 
     As shown in  FIG. 2 , each of the heat exchange elements  10  defines therein a first flow channel  18 , through which a first fluid, such as oil or refrigerant, passes. Each of the heat exchange elements  10  is formed by assembling an upper plate  11  with a lower plate  12  into a single structure. The upper plate  11  and the lower plate  12  are made of a metal material having excellent heat conductivity, such as aluminum, and are joined together along the edges  11   a  and  12   a  by brazing. 
     As shown in  FIG. 2 , the upper plate  11  and the lower plate  12  are provided on facing surfaces thereof with a plurality of flow grooves  11   b  and  12   b . Described in detail, the lower surface of the upper plate  11  is provided with a plurality of upper flow grooves  11   b  and the upper surface of the lower plate  12  is provided with a plurality of lower flow grooves  12   b . The upper flow grooves  11   b  of the upper plate  11  and the lower flow grooves  12   b  of the lower plate  12  diagonally extend on a flat plane. Here, the upper plate  11  and the lower plate  12  are stacked in such a way that the upper flow grooves  11   b  of the upper plate  11  intersect with the lower flow grooves  12   b  of the lower plate  12 . Due to the intersection stack of the upper flow grooves  11   b  and the lower flow grooves  12   b , the first flow channel  18  is defined in the heat exchange element  10 . Therefore, in the heat exchange element  10 , the first fluid, for example, oil, can flow zigzag through the first flow channel  18 , so that the flow rate of the first fluid can be increased and the contact surface of the first fluid relative to the heat exchange element can be enlarged to realize improved heat exchange efficiency. 
     Here, the plurality of the flow grooves  11   b  and  12   b  may be formed by subjecting the upper and lower plates  11  and  12  to die-casting or pressing, such as stamping. Further, bulging parts  13   a  and  14   a  are formed in the heat exchange element  10  at locations opposed to the flow grooves  11   b  and  12   b , with a plurality of depressed parts  13   b  and  14   b  defined between the plurality of bulging parts  13   a  and  14   a . Due to the flow grooves  11   b  and  12   b , the upper and lower plates  11  and  12  have respective wave structures  13  and  14 . 
     As shown in  FIG. 2 , each of the heat exchange elements  10  is provided with an inlet port  43  in one end thereof and with an outlet port  44  in the other end thereof. In each of the heat exchange elements  10 , the inlet port  43  and the outlet port  44  communicate with the first flow channel  18 . Further, when the plurality of the heat exchange elements  10  are stacked, the inlet ports  43  and the outlet ports  44  of the elements  10  communicate with each other. 
     Further, the upper plate  11  has an upper flange  23  which is raised upwards from each of the inlet and outlet ports  43  and  44 , and the lower plate  12  has a lower flange  24  which protrudes downwards from each of the inlet and outlet ports  43  and  44 . Here, the upper flange  23  and the lower flange  24  are assembled with each other through fitting. Described in detail, the upper flanges  23  of a lower heat exchange element  10  may be fitted over the respective lower flanges  24  of an upper heat exchange element  10  or the lower flanges  24  of an upper heat exchange element  10  may be fitted into the respective upper flanges  23  of a lower heat exchange element  10 , so that the desired fluid tightness can be realized. Alternatively, the neighboring upper and lower flanges  23  and  24  may be integrated with each other by brazing in a leak proof manner. Therefore, the inlet ports  43  and the outlet ports  44  of the heat exchange elements  10  are hermetically sealed from a second flow channel  28 . 
     In the uppermost heat exchange element  10 , an inlet fitting  25  is mounted to the upper flange  23  of the inlet port  43  and an outlet fitting  26  is mounted to the upper flange  23  of the outlet port  44 . The inlet fitting  25  has an opening  25   a  to which an inlet pipe is connected. The outlet fitting  26  has an opening  26   a  to which an outlet pipe is connected. 
     The upper flow grooves  11   b  of the upper plate  11  extend to areas around the upper flanges  23  and the lower flow grooves  12   b  of the lower plate  12  extend to areas around the lower flange  24 . Further, in the heat exchange element  10 , the upper flow grooves  11   b  of the upper plate  11  intersect with the lower flow grooves  12   b  of the lower plate  12 , thereby defining the first flow channel  18  having an intersecting structure. Therefore, when the first fluid is introduced from the inlet port  43  into the first flow channel  18 , the first fluid flows zigzag both through the upper flow grooves  11   b  of the upper plate  11  and through the lower flow grooves  12   b  of the lower plate  12  prior to being discharged through the outlet port  44 . 
     Here, in the areas around the inlet port  43  and the outlet port  44 , the first fluid severally flows along the intersecting upper and lower flow grooves  11   b  and  12   b , so that the first fluid may stagnate in the areas around the inlet and outlet ports  43  and  44  of the heat exchange element  10 . In an effort to avoid the stagnation of the fluid in the areas around the inlet and outlet ports  43  and  44 , the present invention provides a flow guide structure capable of guiding the first fluid in such a way that the fluid can flow in at least two directions, in other words, the fluid can flow in radial directions in the areas around the inlet and outlet ports  43  and  44 . Therefore, the present invention can prevent the stagnation of the first fluid and can realize increased fluidity of the first fluid. 
     To this end, as shown in  FIG. 3  through  FIG. 7 , the upper plate  11  is provided with at least one upper subsidiary groove  63  in an area around each of the upper flanges  23  and the lower plate  12  is provided with at least one lower subsidiary groove  64  in an area around each of the lower flanges  24 . 
     As shown in  FIGS. 4 and 5 , the upper subsidiary groove  63  is formed by embossing, etc. in such a way that the upper subsidiary groove  63  can intersect with the upper flow grooves  11   b  of the upper plate  11  at a predetermined angle of intersection. 
     Further, as shown in  FIGS. 4 and 5 , the upper flow grooves  11   b  of the upper plate  11  are formed on the rear surfaces of the bulging parts  13   a  of the wave structure  13 , so that the bulging parts  13   a  and the upper flow grooves  11   b  are oriented in the same direction and, accordingly, the upper subsidiary groove  63  intersects with the bulging parts  13   a  at the predetermined angle of intersection. Therefore, in the area around each of the upper flanges  23  of the upper plate  11 , the first fluid can flow in main flow directions (the directions designated by arrow K) in which the fluid flows along the upper flow grooves  11   b  and, at the same time, can flow in at least one subsidiary flow direction (the direction designated by arrow U) in which the fluid flows along at least one upper subsidiary groove  63 . Therefore, in the area around each of the upper flanges  23  of the upper plate  11 , the first fluid can cross-flow both in the main flow directions and in the at least one subsidiary flow direction, so that the first fluid can more evenly, smoothly and constantly flow for the whole length of the upper plate  11  with increased fluidity. 
     As shown in  FIGS. 6 and 7 , the lower subsidiary groove  64  is formed by embossing, etc. in such a way that the lower subsidiary groove  64  can intersect with the lower flow grooves  12   b  of the lower plate  12  at a predetermined angle of intersection. 
     As shown in  FIGS. 6 and 7 , the lower flow grooves  12   b  of the lower plate  12  are formed on the rear surfaces of the bulging parts  14   a  of the wave structure  14  and, accordingly, the bulging parts  14   a  and the lower flow grooves  12   b  are oriented in the same direction. Therefore, the lower subsidiary groove  64  intersects with the bulging parts  14   a  at the predetermined angle of intersection. Thus, in the area around each of the lower flanges  24  of the lower plate  12 , the first fluid can flow in main flow directions (the directions designated by arrow J) in which the fluid flows along the lower flow grooves  12   b  and, at the same time, can flow in at least one subsidiary flow direction (the direction designated by arrow W) in which the fluid flows along at least one lower subsidiary groove  64 . Therefore, in the area around each of the lower flanges  24  of the lower plate  12 , the first fluid can cross-flow both in the main flow directions and in the at least one subsidiary flow direction, so that the first fluid can more evenly, smoothly and constantly flow for the whole length of the lower plate  12  with increased fluidity. 
     As described above, in the present invention, at least one upper subsidiary groove  63  is formed in the area around each of the upper flanges  23  of the upper plate  11  and at least one lower subsidiary groove  64  is formed in the area around each of the lower flanges  24  of the lower plate  12 , thereby guiding the first fluid to at least two flow directions in the area around each of the inlet and outlet ports  43  and  44  of the heat exchange element  10 . Therefore, the present invention can prevent stagnation of the first fluid in the areas and, accordingly, can allow the fluid to smoothly and constantly flow for the whole length of the respective plates  11  and  12 . That is, the present invention increases the fluidity of the first fluid and, accordingly, realizes improved heat exchange efficiency. 
     Further, a second flow channel  28  through which a second fluid, such as cooling water, passes is defined between the stacked heat exchange elements  10 . The second flow channel  28  is defined because the plurality of heat exchange elements are spaced apart from each other at a predetermined interval. 
     To this end, the upper and lower surfaces of each of the heat exchange elements  10 , that is, the upper surface of the upper plate  11  and the lower surface of the lower plate  12  are provided with a plurality of upper and lower spacing lugs  21  and  22 . Here, the plurality of upper spacing lugs  21  are formed on the upper surface of each bulging part  13   a  of the upper plate  11  in such a way that the lugs  21  are spaced apart from each other at regular intervals. In the same manner, the plurality of lower spacing lugs  22  are formed on the lower surface of each bulging part  14   a  of the lower plate  12  in such a way that the lugs  22  are spaced apart from each other at regular intervals. Here, the lower spacing lugs  22  of the upper heat exchange elements  10  are brought into contact with the upper spacing lugs  21  of the lower heat exchange elements  10 . Because the plurality of upper and lower spacing lugs  21  and  22  are brought into contact with each other as described above, the interval between the stacked heat exchange elements  10  is increased and, accordingly, the sectional area of the second flow channel  28  is increased. Further, the spacing lugs  21  and  22  which are in contact with each other may be joined to each other by brazing, etc. The upper spacing lugs  21  and the corresponding lower spacing lugs  22  are located on points at which the upper flow grooves  11   b  and the lower flow grooves  12   b  intersect with each other, so that the stacked structure of the heat exchange elements can have a stable structure. 
     The spacing lugs  21  and  22  may be shaped in the form of any one of a trapezoidal cross-section, a curved cross-section, such as a circular or elliptical cross-section, and a square cross-section. Further, the upper surfaces  21   a  of the respective upper spacing lugs  21  can be brought into close contact with the lower surfaces  22   a  of the corresponding lower spacing lugs  22 , so that the integration of the upper and lower plates  11  and  12  can be more easily accomplished. 
     Further, as shown in  FIG. 2 , the contact surfaces  21   a  and  22   a  of the upper and lower spacing lugs  21  and  22 , that is, the upper surfaces  21   a  of upper spacing lugs  21  and the lower surfaces  22   a  of the lower spacing lugs  22  are provided with respective through holes  21   c  and  22   c . Further, the through holes  21   c  and  22   c  of neighboring spacing lugs  21  and  22  which are in contact with each other communicate with each other. Therefore, the first flow channels  18  of the respective heat exchange elements  10  communicate with each other by means of the through holes  21   c  and  22   c . Therefore, the first fluid, such as oil, inside a heat exchange element can freely flow to the first flow channel  18  of a neighboring heat exchange element  10  through the through holes  21   c  and  22   c , so that the first fluid can be mixed in all of the heat exchange elements  10  and, accordingly, desirably improves the heat exchange efficiency. 
     Further, the upper plate  11  and the lower plate  12  have positioning grooves  11   c  and positioning protrusions  12   c  on corresponding ends  11   a  and  12   a  thereof. Due to the positioning grooves and positioning protrusions, the upper plate  11  and the lower plate  12  can be easily positioned and, accordingly, the preliminary assembly of the upper and lower plates  11  and  12  can be quickly finished during a process of assembling the plates. Therefore, the precise and firm assembly of the upper and lower plates  11  and  12  can be realized.