Abstract:
A heat exchanger includes: fins formed in a wavy shape; and a tube attached with the wavy fins and bent in a zigzag shape. A contact area between the tube and the fins are maximized to thus considerably enhance heat transfer through the fins.

Description:
RELATED APPLICATION  
       [0001]     The present disclosure relates to subject matter contained in priority Korean Application No. 10-2006-0001085, filed on Jan. 4, 2006, which is herein incorporated by reference in its entirety.  
       BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     The present disclosure relates generally to a fin-tube heat exchanger, and, more particularly, to a fin-tube heat exchanger applied for a direct cooling type refrigerator capable of enhancing the efficiency of heat exchange with ambient air.  
         [0004]     2. Description of the Related Art  
         [0005]      FIG. 1  illustrates a general shape of a cabinet  1  of a refrigerator having a refrigerating chamber  10  and a freezing chamber  20 . In general, in a direct cooling type refrigerator, an evaporator is tightly attached in the refrigerating chamber  10  or the freezing chamber  20 , or a mounting plate is formed as an evaporator to directly cool the refrigerating chamber  10  or the freezing chamber  20 . Recently, an indirect cooling type refrigerator in which cooling air is injected to the refrigerating chamber  10  and the freezing chamber  20  has been commonly used. Compared with the indirect cooling type refrigerator, the direct cooling type refrigerator is operated based on a principle that cooling air of the evaporator is directly supplied to the refrigerating chamber  10  or freezing chamber  20  according to natural convection phenomenon of cooled air around the evaporator, instead of separately generating a large quantity of cooling air.  
         [0006]      FIG. 2  illustrates a side view of the structure of the direct cooling type refrigerator of  FIG. 1 .  FIG. 3  illustrates a schematic block diagram showing the construction of a refrigerating cycle of the direct cooling type refrigerator of  FIG. 2 . As shown in  FIGS. 2 and 3 , the direct cooling type refrigerator  9  has a refrigerating cycle in which two evaporators  50  and  60  are connected in series. Namely, the direct cooling type refrigerator  9  includes a cabinet  1  having a refrigerating chamber  10  and a freezing chamber  20 , a compressor  30  for compressing the refrigerant of the refrigerating cycle and generally formed at a lower portion of the cabinet  1 , a condenser  40  for receiving compressed refrigerant in a direction of reference numeral  88  along a refrigerant passage  99  and condensing the refrigerant while emanating heat, a first evaporator  50  tightly attached on a rear surface of the refrigerating chamber  10  and cooling the refrigerating chamber  10  by evaporating the refrigerant from the condenser  40 , a second evaporator  60  tightly attached on a rear surface of the freezing chamber  20  in order to evaporate the refrigerant either from the first evaporator  50  or from the condenser  40  to thus cool the freezing chamber  20 , and a valve  80  for selectively opening a first tube  81  that connects the condenser  40  and the first evaporator  50  and a second tube  82  that connects the condenser  40  and the second evaporator  60 .  
         [0007]     The condenser  40  operates as a heat exchanger to exchange heat generated as the refrigerant is condensed with ambient air. The evaporators  50  and  60  also need to effectively absorb ambient heat as the refrigerant is evaporated.  
         [0008]      FIG. 4  illustrates a perspective view of the structure of a conventional heat exchanger of a direct cooling type refrigerator.  FIG. 5  illustrates a side view of the heat exchanger of  FIG. 4 . In the heat exchanger as shown in  FIGS. 4 and 5 , a plurality of fins  42  for helping heat exchange around the tube  41  through which the refrigerant flows are attached around the tube  41 . The plurality of fins  42  are braze-welded in a state that they point-contact with the tube  41 , as represented by reference numeral  42   a.  Heat exchange between the tube  41  and the fins  42  occurs at this contact.  
       SUMMARY  
       [0009]     In one general aspect, a heat exchanger capable of improving performance of exchanging heat with ambient air and a method of manufacturing such a heat exchanger are provided. Implementations of the heat exchanger may improve freezing and noise prevention performance of a direct cooling type refrigerator by applying the heat exchanger to a condenser or an evaporator of the direct cooling type refrigerator.  
         [0010]     To this end, a heat exchanger may include a tube through which a refrigerant flows, and a fin attached to the tube. The fin may have a nonlinear shape at an interface between the fin and the tube. More particularly, the fin may be shaped to conform with a shape of the tube at the interface between the fin and the tube. The interface between the fin and the tube may define an arc and the fin may have an arcuate shape at the interface. Also, the fin or the tube may have a serpentine shape.  
         [0011]     The tube of the heat exchanger may include multiple parallel portions and the fin may interface with at least two of the parallel portions of the tube and may be shaped to conform with a shape of the tube at the interfaces between the fin and the at least two parallel portions.  
         [0012]     In another general aspect, a heat exchanger may include a tube through which a refrigerant flows, and a plurality of fins attached to the tube. Each of the fins may have a nonlinear shape at an interface between the fin and the tube. More particularly, each of the fins may be shaped to conform with a shape of the tube at the interface between the fin and the tube. Specifically, the interface between the fin and the tube may define an arc, and the fin may have an arcuate shape at the interface.  
         [0013]     The tube of the heat exchanger may include multiple parallel portions and each of the fins may interface with at least two of the parallel portions of the tube and may be shaped to conform with a shape of the tube at the interfaces between each of the fins and the at least two parallel portions.  
         [0014]     Also, a first group of the fins may be attached to an upper surface of the tube and a second group of the fins may be attached to a lower surface of the tube. The fins may be arranged in such a manner that each fin of the first group is placed between two adjacent fins of the second group.  
         [0015]     In yet another general aspect, a refrigerator using heat exchangers as explained above is provided.  
         [0016]     In another general aspect, a method of manufacturing a heat exchanger includes providing a tube through which a refrigerant flows, and attaching a plurality of fins to the tube. Each fin may have a nonlinear shape at an interface between the fin and the tube. More particularly, each fin may be shaped to conform with a shape of the tube at the interface between the fin and the tube. Attaching the fins to the tube may include attaching a first group of fins to an upper surface of the tube and attaching a second group of fins to a lower surface of the tube. Each fin of the first group may be placed between two adjacent fins of the second group.  
         [0017]     In another general aspect, a heat exchanger may include fins formed in a wavy shape, and a tube attached with the wavy fins and bent in a zigzag shape.  
         [0018]     Because the fins for assisting heat exchanging between ambient air and a fluid passing through the tube are formed in the wavy shape and the tube is attached with the wavy surface of the fins and line-contacts or surface-contacts, not point-contacts, the heat transfer area between the fins and tube is increased and the performance of heat exchanging between the tube and the ambient air is highly improved.  
         [0019]     The wavy surfaces of the fins are respectively attached to the upper surface and the lower surface of the tube, so heat of a fluid in the tube can be heat-exchanged with the ambient air through the wavy fins. In this case, the fins attached to the upper surface of the tube and the fins attached to the lower surface of the tube are not positioned on the same planes (namely, they are positioned on different planes), whereby the ambient air of the heat exchanger can be heat-exchanged with fin having a larger sectional area.  
         [0020]     For example, when the heat exchanger works as the condenser so a hot refrigerant flows in the tube and the ambient air has a low temperature compared with that of the heat exchanger, because the fins are arranged in the crisscross manner on different planes of the tube, each fin can contact with cold air which has not been heated by adjacent fins. Namely, when the heat exchanger is positioned horizontally and there is no flow in the ambient air, air heated after being heat exchanged with the fins is naturally move upward by convection without being heat exchanged with the adjacent fins. Accordingly, the fins arranged in the crisscross manner can contact with the ambient cold air and maximize the cooling efficiency.  
         [0021]     The fins surface-attached to the upper surface of the tube and the fins surface-attached to the lower surface of the tube are arranged at uniform gap therebetween, so its mass-production can be improved in terms of fabrication.  
         [0022]     An inner curvature of the wavy fins may be the same as an outer diameter of a section of the tube. Accordingly, because the fins are formed in a wrapping or covering manner, a larger contact area between the tube and the fins can be obtained.  
         [0023]     In addition, both ends of the fins may be attached to the tube in the wrapping manner. Thus, the heat transfer efficiency between the both ends of the tube and fins can be improved and the bonding strength between the fins the tube can be improved.  
         [0024]     Implementations may provide a direct cooling type refrigerator in which the heat exchanger is applied for the condenser and the evaporator.  
         [0025]     Other features will be apparent from the following description, including the accompanying drawings, and the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a perspective view showing a general shape of a cabinet of a refrigerator;  
         [0027]      FIG. 2  is a side view showing the structure of the direct cooling type refrigerator of  FIG. 1 ;  
         [0028]      FIG. 3  is a schematic block diagram showing a refrigerating cycle of the direct cooling type refrigerator of  FIG. 2 ;  
         [0029]      FIG. 4  is a perspective view showing the structure of a conventional heat exchanger of the direct cooling type refrigerator of  FIG. 1 ;  
         [0030]      FIG. 5  is a side view of the conventional heat exchanger of  FIG. 4 ; and  
         [0031]     FIGS.  6  to  8  are views showing the structure of a heat exchanger, in which  FIG. 6  is a perspective view showing the structure of the heat exchanger,  FIG. 7  is a sectional view taken along line VII-VII of  FIG. 6 , and  FIG. 8  is a front view of the heat exchanger of  FIG. 6 .  
     
    
     DETAILED DESCRIPTION  
       [0032]     FIGS.  6  to  8  illustrate the structure of a heat exchanger. As shown in FIGS.  6  to  8 , a heat exchanger  100  includes a tube  101  that allows a fluid to flow therein, and fins  102  and  103  having a nonlinear shape at an interface between the fins  102  and  103  and the tube  101 . For example, as shown in  FIG. 6 , the fins  102  and  103  may be formed in a wavy shape and attached to the top and bottom portions  102   a  and  103   a  of the tube  101 .  
         [0033]     In general, the fins may be shaped to conform with a shape of the tube at the interface between the fins and the tube. For example, a curvature of the inner surface of the wavy fins  102  and  103  may be substantially the same as the outer diameter of the cross-section of the tube  101 , so the contact areas  102   a  and  103   a  can be maximized.  
         [0034]     As shown in  FIG. 8 , the upper fins  102  attached to the upper portion of the tube  101  and the lower fins  103  attached to the lower portion of the tube  101  are arranged in an interdigital manner on different planes with a certain interval therebetween. Thus, each upper fin is placed between two adjacent lower fins. This arrangement also improves the heat exchange capability of the heat exchanger, particularly when the heat exchanger  100  is placed horizontally, since the interdigital arrangement of fins  102  and  103  of the heat exchanger  100  can increase the chances of heat exchanging with ambient cold air.  
         [0035]     Also, because both ends  102   b  and  103   b  of the fins  102  and  103  are attached to the tube  101  in a wrapping manner, the heat transfer between the fins  102  and  103  and the tube  101  can be further increased and the bonding strength between the fins  102  and  103  and the tube  101  can be also increased.  
         [0036]     The heat exchanger  100  constructed as described above can be utilized for various purposes. For example, it can be advantageously applied for the condenser of a direct cooling type refrigerator, for the following reasons. Because the cooling mechanism of a direct cooling type refrigerator is buried in an insulation panel of the cabinet of the refrigerator, a blow fan is not provided. So, if the heat exchange with the ambient air of the condenser is not sufficient, a refrigerant pipe with a sufficient length should be obtained to release the heat generated from the condenser  40 . If the tube of the condenser  40  is lengthened, the amount of refrigerant to be filled in the refrigerant pipe of the condenser  40  is unnecessarily increased, and, when the operation of the compressor is stopped, the amount of high temperature refrigerant flowing into the evaporator due to an internal pressure difference increases, which increase the noise at an outlet of the evaporator. In addition, when the compressor is driven, time to increase the pressure of the condenser  40  to a level required for condensing is lengthened, degrading the efficiency of the refrigerating cycle.  
         [0037]     Thus, by applying the heat exchanger  100  to the condenser  30  of the direct cooling type refrigerator, the length of the pipe of the condenser can be reduced as the heat release efficiency is improved. As a result, the filling amount of the refrigerant required for the refrigerating cycle can be reduced, which reduces the noise generated from the high temperature refrigerant flowing to the evaporator while the compressor is not working, and also reduces the time to reach the condensing pressure required for the condensing operation of the condenser. Therefore, a quiet and quick operation can be implemented.  
         [0038]     In addition, the heat exchanger also can be applied to the evaporator to improve the efficiency of heat transfer of the evaporator, thereby effectively refrigerating the refrigerating chamber or the freezing chamber.  
         [0039]     Implementations of the fin-tube heat exchanger may offer a number of advantages.  
         [0040]     For example, with the wavy fins and the tube attached to the wavy surface of the fins and bent in a zigzag shape, the contact area between the tube and the fins can be maximized in order to increase the heat transfer area between the fins and the tube. Thus, compared to the conventional structure, the efficiency of heat transfer may be improved.  
         [0041]     Also, as noted, the wavy surface of the wavy fins may be attached to the upper and lower surfaces of the tube with the fins surface-attached to the upper surface of the tube and the fins surface-attached to the lower surface of the tube and arranged in an interdigital manner on different planes of the tube. Accordingly, the degradation of heat transfer performance by adjacent fins can be minimized.  
         [0042]     Moreover, because both ends of the fins are attached to the tube in a wrapping manner, the performance of heat transfer between the tube and the fins can be enhanced and the bonding strength between the fins and the tube can be also improved.  
         [0043]     Additionally, by applying the heat exchanger with the improved heat exchange efficiency to the condenser or the evaporator of a direct cooling type refrigerator, the length of the pipe of the condenser or the evaporator can be reduced as the heat release efficiency is improved. Thus, the filling amount of refrigerant required for the refrigerating cycle can be reduced, and an amount of noise generated from the high temperature refrigerant flowing into the evaporator while the compressor is stopped in operation can also be reduced. Also time to reach the condensing pressure required for the condensing operation can be reduced. Thus, quiet and quick operation of the refrigerator can be implemented.  
         [0044]     Other implementations are within the scope of the following claims.