Abstract:
A heater exchanger used to condense a refrigerant in a refrigeration system. The heat exchanger is designed to perform a heat exchanging operation by the use of latent heat of water vaporization, thus having improved heat exchanging efficiency as well as a reduced size. The heat exchanger includes an upper header having a refrigerant inlet port and distributing a refrigerant introduced into the upper header through the refrigerant inlet port; a plurality of heat exchanging tubes connected at upper ends thereof to the upper header and extending in a vertical direction; a lower header connected to lower ends of the heat exchanging tubes and gathering the refrigerant flowing from the heat exchanging tubes, the lower header having a refrigerant outlet port; and a water supply unit assembled with upper portions of external surfaces of the heat exchanging tubes, and feeding water to the tubes to cause a flow of water along the external surfaces of the tubes, thus allowing the water to absorb heat from the refrigerant flowing in the tubes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of Korean Application No. 2002-39840, filed Jul. 9, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates, in general, to heat exchangers used in refrigeration systems, and more particularly, to a water-cooled heat exchanger used to condense a refrigerant in such a refrigeration system.  
           [0004]    2. Description of the Prior Art  
           [0005]    As well known to those skilled in the art, a refrigeration system used with air-conditioning apparatuses includes a compressor, a refrigerant-condensing heat exchanger, a refrigerant-expansion unit, and a refrigerant-evaporating heat exchanger, which are sequentially connected to each other by a refrigerant pipe to create a refrigeration circuit. When the compressor of the refrigeration circuit is operated, a refrigerant circulates through the refrigerant pipe while repeatedly changing its phase by transferring heat to or absorbing heat from the surroundings. The refrigerant system thus cools room air.  
           [0006]    In such a refrigeration system used with air-conditioning apparatuses, the refrigerant-condensing heat exchanger comprises a refrigerant-distributing header which distributes an outlet refrigerant of the compressor to a plurality of heat exchanging tubes, and a refrigerant-gathering header which gathers the condensed refrigerant flowing from the heat exchanging tubes, prior to feeding the gathered refrigerant to the refrigerant-expansion unit. A plurality of heat exchanging fins having a thin plate shape are assembled with the heat exchanging tubes so as to enlarge the heat exchanging area, at which outdoor air comes into contact with the heat exchanger. During an operation of such a refrigerant-condensing heat exchanger, outdoor air, which is forced by a blower fan installed adjacent to the heat exchanger, cools the tubes and fins, thus condensing the refrigerant flowing in the tubes. The phase of the refrigerant in the refrigerant-condensing heat exchanger is changed from a gas phase into a liquid phase.  
           [0007]    However, such a conventional refrigerant-condensing heat exchanger used with refrigeration systems is problematic in that the heat exchanger is cooled only by the air forced by the fan, so the improvement of heat exchanging efficiency is undesirably limited. In addition, the above heat exchanger must have a plurality of heat exchanging fins to enhance the heat exchanging efficiency, so the size of the heat exchanger is undesirably enlarged to accomplish the desired heat exchanging effect. Further, the enlarged size of the heat exchanger undesirably increases the size of a refrigeration system which uses the heat exchanger.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, it is an object of the present invention to provide a heat exchanger used with refrigeration systems, which has a reduced size and an improved heat exchanging efficiency.  
           [0009]    The foregoing and other objects of the present invention are achieved by providing a heat exchanger, comprising: an upper header having a refrigerant inlet port and distributing a refrigerant introduced into the upper header through the refrigerant inlet port; a plurality of heat exchanging tubes connected at upper ends thereof to the upper header and extending in a vertical direction; a lower header connected to lower ends of the heat exchanging tubes and gathering the refrigerant flowing from the heat exchanging tubes, the lower header having a refrigerant outlet port; and a water supply unit assembled with upper portions of external surfaces of the heat exchanging tubes, and feeding water to the tubes to cause a flow of water along the external surfaces of the tubes, thus allowing the water to absorb heat from the refrigerant flowing in the tubes.  
           [0010]    Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
           [0011]    In the heat exchanger, the water supply unit comprises a channel which has a water supply port to supply water into the channel, with upper and lower holes formed on upper and lower walls of the water supply unit so as to allow the heat exchanging tubes to pass through the water supply unit, each of the lower holes having a size larger than that of each of the heat exchanging tubes to allow the water to flow from the water supply unit to the external surfaces of the heat exchanging tubes.  
           [0012]    In an embodiment, each of the heat exchanging tubes has a circular cross-section, and each of the lower holes of the water supply unit has a polygonal shape, whereby corners of the polygonal lower holes are spaced apart from the external surface of the heat exchanging tubes and edges of the polygonal lower holes are in contact with the external surfaces of the heat exchanging tubes.  
           [0013]    In the above heat exchanger, a plurality of support members are projected from an edge of each of the lower holes toward the external surface of an associated heat exchanging tube, thus spacing the external surface of the heat exchanging tube apart from the edge of the lower hole as well as holding the heat exchanging tube without allowing a movement of the tube.  
           [0014]    In an embodiment, each of the heat exchanging tubes has a circular cross-section, with a spiral flow guide formed on the external surface of each heat exchanging tube so as to guide a flow of water. In this embodiment, each of the heat exchanging tubes has an inner diameter of 0.7-2.5 mm, and a thickness of about 0.3-1.0 mm.  
           [0015]    In another embodiment, each of the heat exchanging tubes has a circular cross-section, with a plurality of linear flow guides axially formed on the external surface of each heat exchanging tube so as to guide a flow of water.  
           [0016]    In still another embodiment, the heat exchanging tubes are plate-shaped multi-channel tubes, with a plurality of partitioned refrigerant channels axially formed in each of the heat exchanging tubes. In this embodiment, each of the heat exchanging tubes has a 1.5-2.5 mm thickness, a 5-20 mm width, and a 1.17-1.52 mm diameter of each of the refrigerant channels.  
           [0017]    In the heat exchanger, the upper header, lower header and water supply unit respectively comprise a plurality of upper headers, lower headers, and water supply units, which are closely arranged in a parallel arrangement, with the heat exchanging tubes being arranged between the upper headers and the lower headers to create a set of heat exchanger modules.  
           [0018]    In an aspect of this embodiment, the heat exchanger further comprises: a refrigerant inlet pipe having a distributing manifold and being connected at the distributing manifold to the refrigerant inlet ports of the upper headers so as to distribute the refrigerant into the upper headers; a refrigerant outlet pipe having a gathering manifold and being connected at the gathering manifold to the refrigerant outlet ports of the lower headers so as to gather the refrigerant from the lower headers; and a water supply pipe having a water distributing manifold, and being connected to water supply ports of the water supply units so as to distribute water into the water supply units.  
           [0019]    In addition, a plurality of reinforcing members are assembled with the external surfaces of the heater exchanging tubes at positions between the upper and lower headers, so as to hold the heat exchanging tubes. Each of the reinforcing members is a flat plate, with a plurality of tube passing holes formed on the plate so as to receive the heat exchanging tubes, each of the tube passing holes having a size larger than a cross-sectional size of each of the heat exchanging tubes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
         [0021]    [0021]FIG. 1 is a perspective view, illustrating the construction of a heat exchanger in accordance with an embodiment of the present invention;  
         [0022]    [0022]FIG. 2 is a sectional view of the heat exchanger in accordance with an embodiment of the present invention;  
         [0023]    [0023]FIG. 3 is a sectional view illustrating the construction of the portion “III” of FIG. 2 in detail;  
         [0024]    [0024]FIG. 4 is a sectional view taken along the line IV-IV′ of FIG. 2;  
         [0025]    [0025]FIG. 5 is a view corresponding to FIG. 4 illustrating the construction of a heat exchanger in accordance with a modification of the embodiment of FIG. 4;  
         [0026]    [0026]FIG. 6 is a perspective view illustrating the construction of a heat exchanging tube included in the heat exchanger in accordance with the embodiment of FIG. 1;  
         [0027]    [0027]FIG. 7 is a view corresponding to FIG. 6 illustrating the construction of a heat exchanging tube in accordance with a modification thereof;  
         [0028]    [0028]FIG. 8 is a perspective view illustrating the construction of a heat exchanger in accordance with another embodiment of the present invention;  
         [0029]    [0029]FIG. 9 is a sectional view taken along the line IX-IX′ of FIG. 8;  
         [0030]    [0030]FIG. 10 is a sectional view taken along the line X-X′ of FIG. 9;  
         [0031]    [0031]FIG. 11 is a perspective view illustrating the construction of a heat exchanging tube included in the heat exchanger in accordance with the embodiment of FIG. 8; and  
         [0032]    [0032]FIG. 12 is a view corresponding to FIG. 11 illustrating the construction of a heat exchanging tube in accordance with a modification thereof. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0034]    As illustrated in FIGS. 1 and 2, the heat exchanger in accordance with an embodiment of the present invention comprises a channeled upper header  10  which distributes an outlet refrigerant of a compressor (not shown), a plurality of heat exchanging tubes  40  through which the distributed refrigerant flows while transferring heat to the outside of the tubes  40  so as be condensed, and a channeled lower header  20  which gathers the condensed refrigerant flowing from the heat exchanging tubes  40 . The heat exchanger also includes a water supply unit  30 , which is mounted to the lower surface of the upper header  10  and supplies water to the heat exchanging tubes  40  so as to allow the water to flow down along the external surfaces of the tubes  40 .  
         [0035]    Each of the upper and lower headers  10  and  20  comprises a channeled body, which has a rectangular cross-section, with a refrigerant channel formed in the body. The channeled body of each of the upper and lower headers  10  and  20  is dosed at both ends thereof. A plurality of refrigerant inlet ports  11  are formed on the upper wall of the upper header  10  and introduce a refrigerant into the interior of the upper header  10 . Connected to the refrigerant inlet ports  11  of the upper header  10  is a refrigerant inlet pipe  50  which extends from the refrigerant outlet of the compressor.  
         [0036]    The heat exchanging tubes  40  have a circular cross-section and extend in a vertical direction to have a substantial length capable of allowing the refrigerant to transfer heat to water and air around the tubes  40  while the refrigerant flows through the tubes  40 . The above heat exchanging tubes  40  are connected to the lower portion of the upper header  10  at the upper ends thereof, and are connected to the upper portion of the lower header  20  at the lower ends thereof. In such a case, the upper and lower ends of the heat exchanging tubes  40  communicate with the interior of the upper and lower headers  10  and  20 , respectively. Therefore, the refrigerant is distributed to the heat exchanging tubes  40  by the upper header  10 , and flows through the tubes  40  while transferring heat to water and air around the tubes  40 , thus being condensed prior to being gathered by the lower header  20 . A plurality of refrigerant outlet ports  21  are formed on the lower wall of the lower header  20  and feed the gathered refrigerant from the lower header  20  to a conventional refrigerant-expansion unit (not shown) of a refrigeration system. Connected to the refrigerant outlet ports  21  of the lower header  20  is a refrigerant outlet pipe  60  which extends to the refrigerant-expansion unit.  
         [0037]    The water supply unit  30 , which is mounted to the lower surface of the upper header  10 , comprises a channeled body, which has a hollow rectangular cross-section and defines a water channel. A water supply port  34  is formed at an end of the water supply unit  30 . Connected to the water supply port  34  is a water supply pipe  80  which supplies water to the water supply unit  30 . A plurality of upper and lower holes  31  and  32  are formed on the upper and lower walls of the water supply unit  30  so as to allow the heat exchanging tubes  40  to perpendicularly pass through the water supply unit  30  through the upper and lower holes  31  and  32 .  
         [0038]    The cross-sectional area of each of the lower holes  32  is larger than that of each of the heat exchanging tubes  40 , as illustrated in FIG. 3, thus allowing water from the water supply unit  30  to flow down along the external surfaces of the heat exchanging tubes  40 .  
         [0039]    In this embodiment, the lower holes  32  of the water supply unit  30  may have a rectangular shape, as illustrated in FIG. 4, such that the corners of each rectangular lower hole  32  are spaced apart from the external surface of an associated heat exchanging tube  40  and the edges of the rectangular lower hole  32  are in contact with the external surface of the tube  40  at four positions. The lower holes  32  of the water supply unit  30  thus stably hold the heat exchanging tubes  40  without allowing an undesired movement of the tubes  40 . Water inside the water supply unit  30  thus leaks from the unit  30  through the gaps between the corners of the lower holes  32  and the external surfaces of the heat exchanging tubes  40 , and flows down along the external surfaces of the heat exchanging tubes  40 . Of course, it should be understood that the lower holes  32  may be designed to have a triangular, pentagonal or a hexagonal shape in place of the rectangular shape, without affecting the functioning of the present invention. In addition, the lower holes may be designed to have a circular shape, as illustrated in FIG. 5. In such a case, the inner diameter of the circular lower holes  33  is larger than the outer diameter of the heat exchanging tubes  40 , and the heat exchanging tubes  40  passing through the circular lower holes  33  are held in the holes  33  by a plurality of support rugs  33   a  formed along the edge of each circular lower hole  33 .  
         [0040]    During the process of fabricating the heat exchangers according to this embodiment of the present invention, it is an aspect to design the size and arrangement of the heat exchanging tubes  40 , with an inner diameter of about 0.7-2.5 mm, a thickness of about 0.3-1.0 mm, and an interval of about 2-6 mm between neighboring tubes  40 .  
         [0041]    As illustrated in FIGS. 6 and 7, a spiral flow guide  41  or a linear flow guide  42  may be preferably formed on the external surface of each heat exchanging tube  40 . The spiral or linear flow guides  41  or  42  of the heat exchanging tubes  40  allow water to evenly flow down along the external surfaces of the tubes  40 , and enlarge the heat exchanging surfaces of the tubes  40 , thus enhancing heat exchanging efficiency of the tubes  40 . In the plural embodiments of the present invention, the spiral flow guide  41  of FIG. 6 may be accomplished by a spiral groove or a spiral ridge formed on the external surface of each heat exchanging tube  40 . The linear flow guide  42  of FIG. 7 may be accomplished by a plurality of linear grooves or linear ridges axially extending along the external surface of each heat exchanging tube  40 .  
         [0042]    In order to prevent an undesired deformation-of the heat exchanging tubes  40  caused by an external shock, a plurality of reinforcing members  70  are assembled with the tubes  40  at positions between the upper and lower headers  10  and  20 , as illustrated in FIGS. 1 and 2. Each of the reinforcing members  70  is formed into a flat plate, with a plurality of tube passing holes  71  formed on the plate so as to receive the tubes  40 . The tube passing holes  71  of the reinforcing members  70  have a diameter larger than the outer diameter of the tubes  40 . That is, the tube passing holes  71  of the reinforcing members  70  are designed in the same manner as that of the upper and lower holes  31  and  32  of the water supply unit  30  so as to hold the heat exchanging tubes  40  and allow water to continuously flow down along the external surfaces of the tubes  40  without being blocked by the reinforcing members  70 .  
         [0043]    As illustrated in FIG. 1, in an aspect of the present invention, the heat exchanger may include a plurality of upper headers  10 ,  10 A and  10 B which have the same construction and are arranged in a parallel arrangement, a plurality of lower headers  20 ,  20 A and  20 B which have the same construction and are arranged in a parallel arrangement, and a plurality of water supply units  30 ,  30 A and  30 B, which have the same construction and are arranged in a parallel arrangement. A plurality of heat exchanging tubes  40  are parallely arranged between the upper headers  10 ,  10 A and  10 B and the lower headers  20 ,  20 A and  20 B while being connected to the upper and lower headers, thus creating a set of heat exchanger modules. A plurality of distributing pipes branch from the refrigerant inlet pipe  50 , thus forming a distributing manifold. The distributing pipes of the refrigerant inlet pipe  50  are connected to the refrigerant inlet ports  11  of the upper headers  10 ,  10 A and  10 B, and distribute the outlet refrigerant of the compressor to the plurality of upper headers  10 ,  10 A and  10 B. In the same manner, a plurality of gathering pipes branch from the refrigerant outlet pipe  60 , thus forming a gathering manifold. The gathering pipes of the refrigerant outlet pipe  60  are connected to the refrigerant outlet ports  21  of the lower headers  20 ,  20 A and  20 B, and gather the condensed refrigerant from the plurality of lower headers  20 ,  20 A and  20 B. The water supply pipe  80  also has a water distributing manifold, which is connected to the water supply ports  34  of the plurality of water supply units  30 ,  30 A and  30 B, and distributes water into the water supply units  30 ,  30 A and  30 B.  
         [0044]    [0044]FIG. 8 is a perspective view, illustrating the construction of a heat exchanger in accordance with another embodiment of the present invention. The heat exchanger, according to this embodiment, comprises a plurality of heat exchanging tubes  140  formed as plate-shaped multi-channel tubes, and a plurality of upper and lower headers  110  and  120  formed as a channeled body having an elliptical cross-section. The heat exchanging tubes  140  have a longitudinal flat plate profile, with a predetermined thickness “t” and a predetermined width “w”, as best seen in FIGS.  9  to  11 . A plurality of partitioned refrigerant channels  141  are axially formed in each tube  140 , so the refrigerant flows through the channels  141 .  
         [0045]    The water supply units  130  are mounted to the lower surfaces of the upper headers  110 . The lower holes  132  of the water supply units  130 , through which the heat exchanging tubes  140  pass, are designed such that the width of each lower hole  132  is larger than the thickness “t” of the heat exchanging tube  140 . Therefore, water of the water supply units  130  leaks from the units  130 , and flows down along the external surfaces of the tubes  140 . A plurality of support members  133  are formed along the edge of each lower hole  132 , and hold a heat exchanging tube  140  passing the lower hole  132 . As illustrated in FIG. 12, a linear flow guide  143  may be formed on the external surface of each heat exchanging tube  140 . The linear flow guide  143  of the heat exchanging tubes  140  allows water to evenly flow down along the external surfaces of the tubes  140 , and enlarges the heat exchanging surfaces of the tubes  140 , thus enhancing heat exchanging efficiency of the tubes  140 . The linear flow guide  143  may comprise a plurality of linear grooves or linear ridges which axially extend along the external surface of each heat exchanging tube  140 .  
         [0046]    During the process of fabricating the heat exchangers, according to this embodiment of the present invention, it is preferable to design the size of the heat exchanging tubes  140 , with about a 1.5-2.5 mm thickness, about a 5-20 mm width, and about a 1.17-1.52 mm diameter of each refrigerant channel  141 .  
         [0047]    The operation and effect of the heat exchanger according to the embodiments of the present invention will be described herein below.  
         [0048]    During an operation of the heat exchanger, high pressure and high temperature gas refrigerant, which flows from the compressor through the refrigerant inlet pipe  50 , is distributed to the heat exchanging tubes  40  or  140  by the upper headers  10  or  110 . The distributed refrigerant thus flows to the lower headers  20  or  120  through the tubes  40  or  140  while transferring heat to water and air around the tubes  40  or  140 , thus being condensed and changing its gas phase into a liquid phase. The liquid refrigerant from the heat exchanging tubes  40  or  140  is gathered in the lower header  20  or  120 , prior to being fed to a conventional refrigerant-expansion unit (not shown) of the refrigeration system through the refrigerant outlet pipe  60 .  
         [0049]    In such a case, water is fed into the water supply unit  30  or  130  through the water supply pipe  80 , and is discharged from the unit  30 , 130  through the lower holes  32  or  132  of the unit  30  or  130 , thus flowing down along the external surfaces of the heat exchanging tubes  40  or  140 . The water absorbs heat from the refrigerant while flowing down along the external surfaces of the heat exchanging tubes  40  or  140 . In addition, air around the heat exchanger is forced to pass through the gaps between the heat exchanging tubes  40  or  140  by a blower fan (not shown), thus absorbing heat from the tubes  40  or  140 . Therefore, the forced air, which passes through the gaps between the heat exchanging tubes  40  or  140 , evaporates the water flowing along the external surfaces of the tubes  40  or  140 , so the tubes  40  or  140  are quickly cooled due to latent heat of water vaporization. Heat exchanging efficiency of the heat exchanger, according to the embodiment of the present invention, is thus improved in comparison to conventional heat exchangers.  
         [0050]    As described above, the present invention provides a water-cooled heat exchanger used for condensing a refrigerant in a refrigeration system. In the heat exchanger, water flows along the external surfaces of a plurality of heat exchanging tubes, so heat transferred from the refrigerant flowing through the tubes is absorbed by both the water flowing along the external surfaces of the tubes and air passing through the gaps between the tubes. In such a case, the refrigerant flowing in the heat exchanging tubes is cooled by latent heat of vaporization of water flowing along the external surfaces of the tubes, so heat exchanging efficiency of the heat exchanger, according to the embodiments of the present invention, is thus remarkably improved in comparison to conventional heat exchangers.  
         [0051]    In addition, due to the improved heat exchanging efficiency, it is possible to reduce the size of the heat exchanger, thus reducing the size of a refrigeration system using the heat exchanger.  
         [0052]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.