Abstract:
A heat exchanger including a plurality of first refrigerant tubes, and a plurality of second refrigerant tubes separated from the plurality of first refrigerant tubes in an air flow direction. Further, a diameter of a respective refrigerant tube of the plurality of first refrigerant tubes is smaller than a diameter of a respective refrigerant tube of the plurality of second refrigerant tubes.

Description:
[0001]    This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 10-2007-0088489 filed in the Republic of Korea to Aug. 31, 2007, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a heat exchanger for exchanging heat between refrigerant and air and a refrigeration cycle apparatus having the same, and more particularly, to a heat exchanger in which a plurality of refrigerant tubes through which refrigerant passes are provided back and forth in an air flowing direction and a refrigeration cycle apparatus having the same. 
         [0004]    2. Description of the Background Art 
         [0005]    A refrigeration cycle apparatus for cooling/heating the room using a refrigeration cycle generally includes a compressor, a condenser, an expander, and an evaporator. Further, a heat exchanger including the condenser and the evaporator has a refrigerant channel through which refrigerant passes. 
         [0006]    Various types of heat exchangers exist. For example, in a fin-tube type heat exchanger, a fin for increasing a heat transfer area is coupled with a refrigerant tube through which refrigerant passes. In more detail,  FIG. 1  is a side view illustrating an enlargement of a part of a background art heat exchanger. 
         [0007]    As shown in the background art heat exchanger, refrigerant flows in the inside of a plurality of columns of refrigerant tubes  102  and  104  and air A flows on the surface of a fin  106  that is an enlarged surface connected to external sides of the refrigerant tubes  102  and  104 . To exchange heat between the refrigerant and the air A, the heat exchanger has an optimal heat transfer area suitable for the characteristics of the refrigerant and the air. 
         [0008]    In addition, the columns of refrigerant tubes  102  and  104  are arranged so that refrigerant tubes having the same diameter are positioned back and forth in an air flowing direction and that the latter columns of refrigerant tubes  104  are positioned in the rear between former columns of refrigerant tubes  102 . 
         [0009]    Because a heat transfer coefficient of refrigerant varies in accordance with diameters of the refrigerant tubes  102  and  104 , the temperature of the external sides of the refrigerant tubes varies. Therefore, the amount of heat exchange between the refrigerant and the air varies. In addition, for the air, the row pitch of the refrigerant tubes  102  and  104  is set to have an enough heat transfer area and the optimal heat transfer area of the air varies in accordance with the diameter of the tubes. 
         [0010]    However, the entire volume of the background art heat exchanger having the above structure is determined by the diameters of the refrigerant tubes  102  and  104  and the width L of the fin  106 . Further, the heat exchanger is generally made to have a thin shape. However, because the diameters of the refrigerant tubes  102  and  104  are equal to each other in the heat exchanger having the above-described structure, the heat exchanger cannot be easily made to have a thin shape. 
         [0011]    Further, in the background art heat exchanger having the above-described structure, a dead zone  108  to which the air is not directly transferred exists in the rear parts of the refrigerant tubes  102  and  104  so that the actual heat transfer area is reduced. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, one object of the present invention is to address the above-noted and other drawbacks. 
         [0013]    Another object of the present invention is to provide a heat exchanger capable of being made thin and that minimizes a dead zone to which air and refrigerant are not transferred to improve the heat transfer performance of the heat exchange. 
         [0014]    Yet another object of the present invention is to provide a refrigeration cycle apparatus having a heat exchanger capable of being made thin and that minimizes the pressure loss of refrigerant. 
         [0015]    To achieve these and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention provides in one aspect a heat exchanger including a plurality of first refrigerant tubes, and a plurality of second refrigerant tubes separated from the plurality of first refrigerant tubes in an air flow direction. Further, a diameter of a respective refrigerant tube of the plurality of first refrigerant tubes is smaller than a diameter of a respective refrigerant tube of the plurality of second refrigerant tubes. 
         [0016]    In another aspect, the present invention provides a refrigeration cycle apparatus including a compressor configured to compress a refrigerant, a condenser connected to the compressor and configured to condense the refrigerant, an expander connected to the condenser and configured to expand the refrigerant, and an evaporator connected to the expander and the compressor and configured to evaporate the refrigerant. Further, at least one of the condenser and the evaporator includes a plurality of first refrigerant tubes, and a plurality of second refrigerant tubes separated from the plurality of first refrigerant tubes in an air flow direction, a diameter of a respective refrigerant tube of the plurality of first refrigerant tubes is smaller than a diameter of a respective refrigerant tube of the plurality of second refrigerant tubes, and the at least one of the condenser and the evaporator further includes a connector configured to connect together the respective refrigerant tube of the plurality of first refrigerant tubes and the respective refrigerant tube of the plurality of second refrigerant tubes so that liquid refrigerant passes through the plurality of first refrigerant tubes and that gas refrigerant passes through the plurality of second refrigerant tubes. 
         [0017]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by illustration only, and thus are not limitative of the present invention, and wherein: 
           [0019]      FIG. 1  is a side view illustrating an enlargement of a part of a background art heat exchanger; 
           [0020]      FIG. 2  is an overview illustrating a heat exchanger according to an embodiment of the present invention; 
           [0021]      FIG. 3  is a side view illustrating an enlargement of a part of the heat exchanger according to an embodiment of the present invention; 
           [0022]      FIG. 4  is a perspective view illustrating an enlargement of a part of a fin of  FIG. 3 ; 
           [0023]      FIG. 5  is a partial sectional view illustrating a connector connecting the former and latter columns of refrigerant tubes of  FIG. 3 ; 
           [0024]      FIG. 6  is a graph illustrating a change in performance in accordance with a diameter ratio of the columns of refrigerant tubes of the heat exchanger according to an embodiment of the present invention; 
           [0025]      FIG. 7  is an overview illustrating a refrigeration cycle apparatus having the heat exchanger according to an embodiment of the present invention; and 
           [0026]      FIG. 8  is a graph schematically comparing a heat transfer performance of the heat exchanger according to an embodiment of the present invention with a heat transfer performance of the background art heat exchanger. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0028]      FIG. 2  is an overview illustrating a heat exchanger according to an embodiment of the present invention. As shown, the heat exchanger includes a plurality of columns of refrigerant tubes  2  and  4  through which refrigerant passes and fins  10  coupling the plurality of columns of refrigerant tubes  2  and  4 . Further, the plurality of fins  10  are coupled to the refrigerant tubes  2  and  4  by a predetermined distance. 
         [0029]    In addition, the refrigerant tubes  2  and  4  are longitudinally arranged to be orthogonal to the flowing direction of air A and the fins  10  are arranged to run parallel to the flowing direction of the air A. The refrigerant tubes  2  and  4  also include former columns of refrigerant tubes  2  positioned in the front in the air flowing direction and latter columns of refrigerant tubes  4  positioned in the rear. The former columns of refrigerant tubes  2  and the latter columns of refrigerant tubes  4  are integrally connected to each other so that refrigerant that passes through the refrigerant tubes  2  and  4 . 
         [0030]    In addition, as shown in  FIG. 3 , the refrigerant tubes  2  and  4  are formed so that the diameter D 1  of the former columns of refrigerant tubes  2  is smaller than the diameter D 2  of the latter columns of refrigerant tubes  4 . That is, in the heat exchanger according to the present embodiment, the diameter of the former columns of refrigerant tubes  2  is different from the diameter of the latter columns of refrigerant tubes  4  such that the heat exchanger can be made thinner. In particular, the refrigerant tubes  2  having a small diameter are used for the former columns to increase the flow rate of the refrigerant affected by the sectional area of the tubes and to increase the heat transfer coefficient of the refrigerant tubes, in particular, the heat transfer coefficient of the insides of the former columns of refrigerant tubes  2 . 
         [0031]    Further, when the refrigerant tubes having the small diameter are used, the heat transfer coefficient increases in accordance with an increase in the flow rate of the refrigerant, However, because the heat transfer area of the insides of the refrigerant tubes having the small diameter is reduced, when the refrigerant tubes having the small diameter are used for the former and latter columns of refrigerant tubes of the heat exchanger, the total heat transfer amount is reduced so that the pressure loss of the refrigeration apparatus is increased. In addition, when the refrigerant tubes having the small diameter and the refrigerant tubes having the large diameter are mixedly used for the former and latter columns of refrigerant tubes  2  and  4 , the increase in heat transfer coefficient caused by the increase in the refrigerant flow rate and the increase in the pressure loss are offset so that the heat transfer amount is increased overall. 
         [0032]    Further, the pressure loss is reduced than when all of the former and latter columns of the refrigerant tubes  2  and  4  are formed of the tubes having the large diameter. That is, although the distance SP between the former and latter columns of refrigerant tubes  2  and  4  is reduced, the pressure loss of the air is not increased. Also, when the distance SP between the former and latter columns of refrigerant tubes  2  and  4  is reduced, the fin efficiency can be increased. In addition, due to the reduction in the pressure loss of the air, the noise is minimized and the power consumption of a fan for flowing the air to the heat exchanger is reduced. 
         [0033]    In addition, when the refrigerant tubes having the small diameter are used as the former columns of refrigerant tubes  2 , a dead zone in the rear of the former columns of refrigerant tubes  2  is smaller than when the former columns of refrigerant tubes  2  have the same diameter as the diameter of the latter columns of refrigerant tubes  4 . 
         [0034]    Also, as shown in  FIG. 3 , the size of former columns of colars  12  coupled to the former columns of refrigerant tubes  2  is smaller than the size of latter columns of colars  14  coupled to the latter columns of refrigerant tubes  4 . Further, the diameter of the latter columns of refrigerant tubes  4  is preferably set to be 3 mm to 12 mm and the former columns of refrigerant tubes  2  and the latter columns of refrigerant tubes  4  are formed so that the distance SP between the tubes is 15 mm to 25 mm in a direction perpendicular to the flowing direction of the air. 
         [0035]    As illustrated in  FIGS. 3 and 4 , when the fin  10  is divided back and forth into a forward fin unit  16  around the former columns of refrigerant tubes  2  and a backward fin unit  18  around the latter columns of refrigerant tubes  4  in the flowing direction of the air, the sum of the width RP 1  of the forward fin unit  16  and the width RP 2  of the backward fin unit  18  is about 10 mm to 30 mm. 
         [0036]    Further, the fin  10  also includes slits  20  and  22  that increase the heat transfer area through which the air passes. In this embodiment, at least three columns of forward slits  20  are formed in the forward fin unit  16  and at least three columns of backward slits  22  are formed in the backward fin unit  18 . 
         [0037]    Also, the length SL 1  of the forward slits  20  is preferably 0.3 mm to 1.5 mm and the length SL 2  of the backward slits  22  is preferably 0.3 mm to 1.5 mm. The forward slits  20  and the backward slits  22  are also asymmetrical with each other so that heat transfer performance is maximally improved. Further, the area of a space between the former columns of refrigerant tubes  2  in the forward fin unit  16  is larger when the diameter of the former columns of refrigerant tubes  2  is different from the diameter of the later columns of refrigerant tubes  4  than when the diameter of the former columns of refrigerant tubes  2  is equal to the diameter of the latter columns of refrigerant tubes  4 . In addition, the length SL 1  of the forward slits  20  is longer than the length SL 2  of the backward slits  22 . 
         [0038]    Further, the width d 1  of the forward slits  20  and the width d 2  of the backward slits  22  are preferably 0.5 mm to 2 mm. The slits  20  and  22  are also formed in the same or opposite directions as to the direction in which the colars  12  and  14  protrude and the minimum distance between adjacent slits is preferably 0.5 mm. 
         [0039]    In addition, in the slits  20  and  22 , the length SL 1 , the width d 1 , and the number of former columns of slits  20  are designed to be optimal in accordance with the area of the latter columns of slits  22  and the area of the parts excluding the slits  20  and  22  so as to maximally secure the heat transfer performance. The distance between the slits is also designed so that condensed water can be easily discharged to actively transfer heat. In addition, the length SL 2 , the width d 2 , and the number of the latter columns of slits  22  are designed in accordance with the fin area different from the fin area of the former columns of slits  20  so that it is possible to maximally transfer the heat. 
         [0040]    Further, as shown in  FIG. 3 , flat units  17  and  19  are formed between the slits in the forward fin unit  16  and the backward fin unit  18  and the widths d 3  and d 4  of the flat units  17  and  19  are made large so that the condensed water can be easily discharged. In addition, as illustrated in  FIG. 5 , a U-shaped connector  24  connected to a former column of refrigerant tube  2  and a latter column of refrigerant tube  4  is provided to connect the refrigerant tubes  2  and  4 . 
         [0041]    The connector  24  is also formed so that the diameter D 3  of a part  26  connected to the former column of refrigerant tube  2  is smaller than the diameter D 4  of a part  28  connected to the latter column of refrigerant tube  4 . In addition, the connector  24  is formed so that the area of a channel increases from the part connected to the former column of refrigerant tube  2  toward the part  28  connected to the latter column of refrigerant tube  4 . 
         [0042]    Next,  FIG. 6  is a graph illustrating a change in performance in accordance with the diameter ratio of the former and latter columns of refrigerant tubes of the heat exchanger according to an embodiment of the present invention. In particular,  FIG. 6  illustrates a heat transfer performance in accordance with the ratio D 1 /D 2  of the tubes  2  and  4 . 
         [0043]    Further,  FIG. 6  illustrates an embodiment when the diameter of the latter columns of refrigerant tubes  4  is 3 mm to 12 mm, the distance SP between the former columns of refrigerant tubes  2  and the distance SP between the latter columns of refrigerant tubes  4  are 11 mm to 25 mm and when the width of the air flowing direction of the fin is 10 mm to 30 mm. 
         [0044]    As shown, proper heat transfer performance can be maintained when the ratio D 1 /D 2  is 0.3 to 0.95. Further, the heat transfer performance rapidly deteriorates when the ratio D 1 /D 2  is Less than 0.3. That is, in the heat exchanger according to an embodiment of the present embodiment, the ratio D 1 /D 2  is 0.3 to 0.95. For example, when the diameter D 2  of the latter columns of refrigerant tubes  4  is 7 mm, the diameter of the former columns of refrigerant tubes  2  is set to be 2.1 mm to 6.65 mm. 
         [0045]    Next,  FIG. 7  is an overview illustrating a refrigeration cycle apparatus having the heat exchanger according to an embodiment of the present invention. As shown, the refrigeration cycle apparatus includes a compressor  32  for circulating refrigerant, a condenser  34 , an expander  36  and an evaporator  38 . Also included is a condenser fan  35  for blowing the air to the condenser  34  rotatably provided around the condenser  34 . An evaporator fan  39  for blowing the air to the evaporator  38  is also rotatably provided around the evaporator  38 . 
         [0046]    Further, in the refrigeration cycle apparatus, the evaporator  38  functions as an indoor heat exchanger for extracting heat from the indoor air and evaporating the refrigerant, and the condenser  34  functions as an outdoor hear exchanger for discharging heat to the outdoor air and condensing the refrigerant. 
         [0047]    Further, at least one of the condenser  34  and the evaporator  38  is formed of the heat exchanger illustrated in  FIGS. 2 to 5 . That is, at least one of the condenser  34  and the evaporator  38  is formed so that the diameter of the former columns of refrigerant tubes  2  is smaller than the diameter of the latter columns of refrigerant tubes  4  in the flowing direction of the air. In the next description, both of the condenser  34  and the evaporator  38  are formed of the heat exchanger illustrated in  FIGS. 2 to 5 . 
         [0048]    Further, when the condenser  34  and the evaporator  38  are connected to each other so that liquid refrigerant passes through the former columns of refrigerant tubes  2  and that gas refrigerant passes through the latter columns of refrigerant tubes  4 , the condenser  34  and the evaporator  38  can be made thin and the pressure loss of the refrigerant is minimized. 
         [0049]    In addition, in the condenser  34 , the latter columns of refrigerant tubes  4 , the former columns of refrigerant tubes  2 , and the expander are sequentially connected to each other in a refrigerant flowing direction so that the refrigerant compressed by the compressor  32  passes through the latter columns of refrigerant tubes  4 , passes through the former columns of refrigerant tubes  2 , and flows to the expander. 
         [0050]    In the evaporator  38 , the former columns of refrigerant tubes  2  and the latter columns of refrigerant tubes  4  are sequentially connected to each other in a refrigerant flowing direction so that the refrigerant expanded by the expander  36  passes through the former columns of refrigerant tubes  2 , passes through the latter columns of refrigerant tubes  4 , and flows to the compressor  32 . 
         [0051]    Next,  FIG. 8  is a graph schematically comparing a heat transfer performance of the heat exchanger according to an embodiment of the present invention with a heat transfer performance when the diameters of the background art heat exchanger. 
         [0052]    In more detail, in  FIG. 8 , the heat transfer performance is illustrated when the diameter of the former columns of refrigerant tubes  2  is 5 mm, the diameter of the latter columns of refrigerant tubes  4  is 7 mm, the sum of the width RP 1  of the forward fin unit  16  and the width RFP 2  of the backward fin unit  18  is about 20 mm, the distance between the center of the former column of refrigerant tube  2  and the center of the Latter column of refrigerant tube  4  is 9.5 mm, and the heat exchanger is used as the evaporator and the condenser and is compared with the heat transfer performance when the diameter of the former columns of refrigerant tubes  2  and the diameter of the latter columns of refrigerant tubes  4  are 7 mm, the sum of the width RP 1  of the forward fin unit  16  and the width RFP of the backward fin unit  18  is about 25.4 mm, the distance between the center of the former column of refrigerant tube  2  and the center of the latter column of refrigerant tube  4  is 10.5 mm, and the heat exchanger is used as the evaporator and the condenser. 
         [0053]    As shown, the heat transfer performance of the present invention is greater than that of the background art. That is, in the heat exchanger according to the present embodiment, as illustrated in  FIG. 5 , although the width RP 1  of the forward fin unit  16  of the fin  10  and the width RP 2  of the backward fin unit  18  of the fin  10  are smaller, when the heat exchanger is used as the evaporator and the condenser, the heat transfer performance is higher than when the diameter of the former columns of refrigerant tubes  2  and the diameter of the latter columns of refrigerant tubes  4  are 7 mm. 
         [0054]    In the heat exchanger according to embodiments of the present invention having the above structure, among the plurality of columns of referigerant tubes, the diameter of the former columns of refrigerant tubes is smaller than the diameter of the latter columns of refrigerant tubes in the air flowing direction. Therefore, the heat exchanger can be made thin in the air flowing direction and a dead zone in which air and heat are not exchanged among the refrigerant tubes of the heat exchanger can be minimized to improve the heat transfer performance. 
         [0055]    In the refrigeration cycle apparatus having the heat exchanger according to the present invention, liquid refrigerant flows through the former columns of refrigerant tubes having the small diameter and gas refrigerant flows through the latter columns of refrigerant tubes having the large diameter so that the condenser and the evaporator can be made thin and the pressure loss of the refrigerant can be minimized. 
         [0056]    Thus, according to an embodiment of the present invention, the heat exchanger includes the plurality of columns of refrigerant tubes and the diameter of the former columns of refrigerant tubes is smaller than the diameter of the latter columns of refrigerant tubes in the air flowing direction. Therefore, the heat exchanger can be made thin and can be used for a refrigeration cycle apparatus capable of minimizing the pressure loss of the refrigerant. The dead zone and pressure loss can also be minimized. 
         [0057]    As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.