Abstract:
A spray type heat exchange device includes a spray unit, a first group set of heat transfer tubes, at least a distributing unit and a second group set of heat transfer tubes. The distributing unit redistributes the remaining liquid refrigerant that is sprayed out from the spray unit and flowed through the first group set of heat transfer tubes, and the remaining liquid refrigerant is dropped downwardly to the second group set of heat transfer tubes. By this disclosed method, the inner space of the heat exchange device could be fully utilized to configure and accommodate more heat transfer tubes therein.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a heat exchange device applicable in a chiller system, and more particularly, a spray type heat exchange device that the liquid refrigerant flows from upward to downward. 
         [0003]    2. Description of Related Art 
         [0004]    A conventional cooling system mainly comprises four components: compressor, expansion device, evaporator and condenser. Therein, the evaporator is implemented by making low temperature liquid refrigerant contact the surface of heat transfer tubes with high temperature object fluid flowing therein and remove heat from the surface, thereby cooling the fluid. Currently, for concerning the environmental protection and cost saving, it is a criterion of decreasing the filled refrigerant inside the cooling system without decreasing heat exchange efficiency. 
         [0005]    Many improvements have been made on evaporator of the cooling system in recent years. There are three types of evaporators: direct expansion type, flooded type and spray type. The direct expansion type evaporator is one kind of shell-and-tube heat exchanger, wherein refrigerant flows in inner side of tubes and object fluid flows in shell side. However, to prevent liquid refrigerant that is not completely evaporated from being absorbed into compressor and damaging compressor, the refrigerant flows into the compressor that needs to be overheated and causes the power consumption of the compressor increased. 
         [0006]    The flooded type evaporator is also one kind of shell-and-tube heat exchanger, wherein object fluid flows in inner side of tubes while refrigerant flows in shell side. The liquid refrigerant is not easy to enter into the inlet of the compressor in this type of evaporator. However, since tubes of the flooded type evaporator need to be immersed in liquid refrigerant in the shell side of the flooded type evaporator, a great deal of liquid refrigerant is required. Quantity of the refrigerant filled in the flooded type evaporator might be over two times that of the refrigerant filled in the direct expansion type evaporator, which accordingly increases the cost and increases environment burden. 
         [0007]      FIG. 1  is a sectional diagram of a conventional spray type evaporator  101 . As shown in  FIG. 1 , the spray type evaporator  101  has a shell  1015 , a spray unit  1011  disposed at upper portion inside of the shell  1015 , and a plurality of heat exchanged tubes  1013  disposed in horizontal direction below the spray unit  1011 . Through the inlet of the evaporator above the spray unit  1011 , liquid refrigerant enters into the spray unit  1011 , and passes through a plurality of small holes (not shown) formed on lower surface of the spray unit  1011  and drips downward to the heat transfer tubes  1013  that are alternately arranged below the spray unit  1011 , thereby forming a refrigerant film on the surface of heat transfer tubes  1013  for heat exchange. As shown in dashed lines of  FIG. 1 , vaporized refrigerant is dissipated upward through spacing between the shell  1015  and the spray unit  1011 . 
         [0008]    In addition, as disclosed by Taiwan Patent No. M247805, refrigerant can drip down to heat transfer tubes through a flooded plate and a distributing unit for heat exchange. U.S. Pat. Nos. 5,836,382, 6,167,713, 6,868,695 also change structure of the spray unit for improving efficiency of refrigerant drips to heat transfer tubes. Moreover, as disclosed by U.S. Pat. No. 5,904,807, structure of upper portion of the evaporator is changed such that liquid refrigerant can be directly injected into the spray structure for increasing the spraying effect. 
         [0009]    However, in the above-described spray type evaporators, the spray device is disposed far away from the refrigerant inlet so as to increase the dripping area of the liquid refrigerant on heat transfer tubes which increases the spraying area, and leaves less space for disposing of heat transfer tubes. Accordingly, to reach expected heat exchange efficiency, shell size of the evaporator needs to be increased, which consumes space, increases the cost of material and fabrication. 
         [0010]    Therefore, there is a need to provide a device used in this kind of evaporator with refrigerant flowing downward, wherein a same number of tubes can be disposed without increasing the shell size so as to drop the material cost, or much more heat transfer tubes can be disposed in a same shell size so as to increase the heat exchange area, thereby improving the heat exchange efficiency and saving the shell space. 
       SUMMARY OF THE INVENTION 
       [0011]    According to the above drawbacks, a primary objective of the present invention is to provide a spray type heat exchange device capable of increasing the space usage. 
         [0012]    Another objective of the present invention is to provide a spray type heat exchange device, that a same number of heat transfer tubes can be disposed in smaller shell size as compared to the prior art, thereby decreasing the fabrication cost. 
         [0013]    In order to attain the above and other objectives, the present invention discloses a spray type heat exchange device, inside shell of which there are disposed: a spray unit for downwardly spraying refrigerant; a first group set of heat transfer tubes capable of contacting the refrigerant sprayed out from the spray unit for heat exchange; and a second group set of heat transfer tubes disposed below the first group set of heat transfer tubes and capable of contacting the refrigerant dripped from the first group set of heat transfer tubes for heat exchange. 
         [0014]    In a preferred embodiment, at least one distributing unit is disposed between the first and second group sets of heat transfer tubes, the distributing unit having a plurality of dripping holes and/or dripping slots disposed on surface thereof. 
         [0015]    As at least one distributing unit is disposed between the first and second group sets of heat transfer tubes, a large spraying area can be obtained without the need of disposing the spray unit at a position far away from the refrigerant inlet of the heat exchange device. The heat transfer tubes can further be disposed between the distributing unit and the spray unit for increasing the space usage and heat exchange efficiency, or alternatively, a same number of heat transfer tubes can be used with smaller shell size of the heat exchange device, thereby reducing the fabrication cost. 
         [0016]    The present invention also discloses a spray type heat exchange device according to another embodiment, inside shell of which there are disposed: a spray unit for downwardly spraying liquid refrigerant; a first group set of heat transfer tubes capable of contacting the liquid refrigerant sprayed out from the spray unit for heat exchange; a second group set of heat transfer tubes disposed below the first group set of heat transfer tubes and capable of contacting the refrigerant dripped from the first group set of heat transfer tubes for heat exchange; and a third group set of heat transfer tubes disposed below the second group set of heat transfer tubes and capable of contacting the liquid refrigerant dripped from the second group set of heat transfer tubes for heat exchange. 
         [0017]    In a preferred embodiment, at least one distributing unit having a plurality of dripping holes and/or dripping slots on surface thereof is disposed between the first and second group sets of heat transfer tubes and between the second and third group sets of heat transfer tubes. 
         [0018]    Through the two layer distributing units and the three group sets of heat transfer tubes, it is possible to maximally utilize space and efficiently dispose heat transfer tubes inside the heat exchange device. 
         [0019]    In a preferred embodiment, the distributing unit has a nearly U-shaped section. Preferably, walls around the distributing unit extend obliquely outward so as to receive dripped refrigerant for increasing larger area. 
         [0020]    In preferred embodiment, the distributing unit has a smooth curve shaped section with the opening upward so as to receive dripped refrigerant in a much larger area. 
         [0021]    In a preferred embodiment, spacing is formed between the distributing unit and the shell and/or between the distributing units such that vaporized refrigerant can flow up and flow out of the evaporator. 
         [0022]    In a preferred embodiment, adjacent upper and lower columns of heat transfer tubes are alternately arranged such that refrigerant flowing through an upper column of heat transfer tubes and dripping down can pass through spacing of a lower column of heat transfer tubes and drip down to a next lower column of heat transfer tubes, thereby maximizing the space usage and disposing heat transfer tubes more efficiently. 
         [0023]    In a embodiment, the spray unit is disposed at a position such that distance from spray surface of the spray unit to lower side of the top portion of the shell is 5% to 25% of the inner diameter of the shell, and the distributing unit is disposed at a position such that distance from surface of the distributing unit to lower side of the top portion of the shell is 40% of the inner diameter of the shell, thereby maximizing the number of heat transfer tubes disposed inside the heat exchange device. Out of this embodiment, the other portions could be applied in realizing this invention. 
         [0024]    In another embodiment, the spray unit is disposed at a position such that distance from spray surface of the spray unit to lower side of the top portion of the shell is 5% to 25% of the inner diameter of the shell, the distributing unit between the first and second group sets of heat transfer tubes is disposed at a position such that distance from surface of the distributing unit to lower side of the top portion of the shell is 20% to 30% of the inner diameter of the shell, and the distributing unit between the second and third group sets of heat transfer tubes is disposed at a position such that distance from surface of the distributing unit to lower side of the top portion of the shell is 45% to 50% of the inner diameter of the shell, thus maximizing the number of heat transfer tubes disposed inside the heat exchange device. Out of this embodiment, the other portions could be applied in realizing this invention. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0025]      FIG. 1  is a sectional diagram of a conventional spray type evaporator; 
           [0026]      FIG. 2  is a sectional diagram of a spray type heat exchange device according to a first embodiment of the present invention; 
           [0027]      FIG. 3  is a spray type heat exchange device according to a second embodiment of the present invention; 
           [0028]      FIG. 4  is a sectional diagram showing another embodiment of the spray type heat exchange device of the first embodiment of the present invention; and 
           [0029]      FIG. 5  is a sectional diagram showing another embodiment of the spray type heat exchange device of the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0030]    The following illustrative embodiments are provided to illustrate the disclosure of the present invention, these and other advantages and effects can be apparent to those skilled in the art after reading the disclosure of this specification. The present invention can also be performed or applied by other different embodiments. The details of the specification may be on the basis of different points and applications, and numerous modifications and variations can be made without departing from the spirit of the present invention. 
         [0031]      FIG. 2  is a sectional diagram of a spray type heat exchange device  1  according to a first embodiment the present invention. As shown in  FIG. 2 , the spray type heat exchange device  1  has a shell  15 . Inside the shell  15  there are disposed sequentially, a spray unit  11 , a first group set of heat transfer tubes  13 , a distributing unit  17 , and a second group set of heat transfer tubes  19 . 
         [0032]    The spray unit  11  has an inlet  111  connected with a refrigerant supply source (not shown), and a spray surface  112  having a plurality of dripping holes or dripping slots (not shown) disposed thereon for allowing the refrigerant to drip downward. There are no special limits on size, shape and distribution of the dripping holes or dripping slots, as long as liquid refrigerant can be uniformly dripped through the whole spray surface  112  in coordinate with supply of the refrigerant. The dripping holes or slots are preferably located at a position corresponding to the heat transfer tubes such that refrigerant dripped from the dripping holes or slots can fall on the corresponding heat transfer tubes. 
         [0033]    The first group set of heat transfer tubes  13  comprise a plurality of heat transfer tubes  131  arranged in parallel with each other. An object fluid that requires to be cooled flows through the heat transfer tubes  131 . Adjacent upper and lower heat transfer tubes  131  are alternately arranged. That is, a next column of heat transfer tubes  131  is arranged at a position corresponding to spacing of a previous column of heat transfer tubes  131 . Thus, much more heat transfer tubes  131  can be arranged in a same space. 
         [0034]    The distributing unit  17  has a nearly opened rectangular section and in the shape of a shallow plate. A whole surface  171  of the distributing unit  17  has a plurality of dripping holes and/or dripping slots disposed thereon so as to increase the dripping area and dripping uniformity. Similarly, there are no special limits on size, shape and distribution of the dripping holes or slots, as long as liquid refrigerant can be uniformly dripped through the whole surface  171  in combination with supply of the refrigerant. The dripping holes or slots are preferably located at a position corresponding to the heat transfer tubes such that refrigerant dripped from the dripping holes or slots can fall on the corresponding heat transfer tubes 
         [0035]    The second group set of heat transfer tubes  19  comprise a plurality of heat transfer tubes  191  arranged in parallel with each other. An object fluid that requires to be cooled flows through the heat transfer tubes  191 . Same as the first group set of heat transfer tubes  13 , the heat transfer tubes  191  are also alternately arranged. 
         [0036]    The operation of the spray type heat exchange device  1  is described as follows. First, liquid refrigerant from the supply source enters into the spray unit  11  through the inlet  111  of the spray unit  11 , and passes through the plurality of dripping holes or dripping slots of the spray surface  112  to drip downward. Then, the dripped liquid refrigerant flows through surfaces of the heat transfer tubes  131  of the first group set of heat transfer tubes  13  disposed below the spray unit  11  so as to make heat exchange with the object fluid flowing through the heat transfer tubes  131 , thereby cooling the object fluid. 
         [0037]    Further, the refrigerant flowing through the first group set of heat transfer tubes  13  drips down to the distributing unit  17 . The refrigerant dripping to the distributing unit  17  is then collected in the distributing unit  17 , drips downward through the dripping holes or dripping slots of the surface  171 , and flows through the surfaces of the heat transfer tubes  191  of the second group set of heat transfer tubes  19  disposed below the distributing unit  17  so as to make heat exchange with the object fluid flowing through the heat transfer tubes  191 , thereby cooling the object fluid. 
         [0038]    During heat exchange between refrigerant and the heat transfer tubes  131  or  191 , a part of liquid refrigerant absorbs the heat and is vaporized. The vaporized refrigerant then passes through spacing  21  between the distributing unit  17  and the shell  15 , and spacing  20  between the spray unit  11  and the shell  15 , and reaches to the outlet  151  of the evaporator. 
         [0039]    Positions of the spray unit  11  and the distributing unit  17  can be adjusted according to the practical need such that a maximum number of heat transfer tubes can be disposed inside the heat exchange device. For example, if the shell  15  of the spray type heat exchange device  1  substantially has a ring-shaped section and inner diameter of the shell is D, the spray unit  11  can be disposed at a position such that distance from the spray surface  112  of the spray unit  11  to lower side of the top portion of the shell  15  is 5% to 25% of the inner diameter D of the shell  15 , and the distributing unit  17  can be disposed at a position such that distance from the surface  171  of the distributing unit  17  to lower side of the top portion of the shell  15  is about 40% of the inner diameter D of the shell  15 . 
         [0040]    Through the present embodiment, a big spray area can be obtained without the need of disposing the spray unit at a position far away from the inlet of the heat exchange device, and heat transfer tubes can be disposed between the distributing unit  17  and the spray unit  11  for increasing the space usage and heat exchange efficiency, or alternatively, a same number of heat transfer tubes can be used with decreased the size of the heat exchange device, thereby reducing the fabrication cost. 
         [0041]      FIGS. 3 to 5  show other embodiments of the present invention, wherein components are the same as those in the first embodiment and designated by same symbols, the detailed description of them is omitted. 
         [0042]      FIG. 3  is a sectional diagram of a spray type heat exchange device according to a second embodiment of the present invention. As shown in  FIG. 3 , besides a spray unit  11 , a first group set of heat transfer tubes  13 , two distributing units  17 - 1 ,  17 - 2 , and a second group set of heat transfer tubes  19  that are disposed sequentially in shell  15  of a spray type heat exchange device  2 , the spray type heat exchange device  2  has another distributing unit  23  and a third group set of heat transfer tubes  25  disposed below the second group set of heat transfer tubes  19 . 
         [0043]    The distributing unit  23  has a nearly opened rectangular section and in the shape of a shallow plate. The distributing unit  23  also has a plurality of dripping holes and/or dripping slots disposed on a whole surface  231  thereof. Similarly, there are no special limits on size, shape and distribution of the dripping holes or slots, as long as the liquid refrigerant can uniformly drip through the surface  231  in combination with supply of refrigerant. The dripping holes or dripping slots are preferably located at a position corresponding to the heat transfer tubes such that refrigerant dripped through the dripping holes or dripping slots can fall on the corresponding heat transfer tubes. 
         [0044]    The third group set of heat transfer tubes  25  comprise a plurality of heat transfer tubes  251  arranged in parallel with each other. An object fluid that requires to be cooled flows through the heat transfer tubes  251 . Similarly, upper and lower columns of heat transfer tubes  251  are alternately arranged. 
         [0045]    In the present embodiment, two layer distributing units and three group sets of heat transfer tubes that are disposed in the heat exchange device allow a more flexible disposing method of the spray units, the distributing units and the heat transfer tubes in the practical need. This makes it possible to dispose a maximum number of heat transfer tubes in a limited space of the heat exchange device. For example, if the shell  15  of the spray type heat exchange device  2  has a ring-shaped section and inner diameter of the shell is D, the spray unit  11  can be disposed at a position such that distance from spray surface  112  of the spray unit  11  to lower side of the top portion of the shell  15  is 5% to 25% of the inner diameter D of the shell  15 , and the distributing units  17 - 1  and  17 - 2  can be disposed at a position such that distance from the surfaces  171 - 1  and  171 - 2  to lower side of the top portion of the shell  15  is about 20% to 30% of the inner diameter D of the shell  15 , and the distributing unit  23  can be disposed at a position such that distance from surface  231  of the distributing unit  23  to lower side of the top portion of the shell  15  is about 45% to 50% of the inner diameter D of the shell  15 . 
         [0046]    Further, in the present embodiment, as spacing  21 ′ is formed between the distributing units  17 - 1  and  17 - 2 , vaporized refrigerant can smoothly rise up and flow out of the evaporator. 
         [0047]    Although the present embodiment exemplifies two layer distributing units, the present invention is not limited thereto. Instead, much more layer distributing units can be disposed for receiving remaining liquid refrigerant several times. 
         [0048]      FIG. 4  is a sectional diagram showing another embodiment of the spray type heat exchange device of the first embodiment of the present invention. As shown in  FIG. 4 , the walls of the distributing unit  17 ′ extend obliquely outward so as to receive dripped refrigerant in a much bigger area. 
         [0049]      FIG. 5  is a sectional diagram showing another embodiment of the spray type heat exchange device of the second embodiment of the present invention. As shown in  FIG. 5 , each of the distributing units  17 - 1 ′,  17 - 2 ′ and  23 ′ has a smooth curve shaped section with the opening upward so as to receive dripped refrigerant in a larger area. In addition, through such a shape design, dead spots that collect refrigerant and prevent refrigerant from dripping can be avoided. 
         [0050]    The above-described descriptions of the detailed embodiments are only to illustrate the preferred implementation according to the present invention, and it is not to limit the scope of the present invention, Accordingly, all modifications and variations completed by those with ordinary skill in the art should fall within the scope of present invention defined by the appended claims.