Abstract:
[Problem] 
     A refrigerant supply device with a small lateral width and a capacity to supply refrigerant evenly among heat receivers disposed in multiple tiers needs to be provided. 
     [Solution] 
     A refrigerant supply device for distributing, by force of gravity, liquid phase refrigerant to heat receivers disposed in a plurality of tiers includes: a first conduit for supplying the refrigerant to the heat receivers; a second conduit provided in parallel with the first conduit; a first aperture provided in the first conduit for supplying the refrigerant to one of the heat receivers; a first blocking means provided below the first aperture for blocking the first conduit; a first communication opening provided above the first aperture and communicating the first conduit and the second conduit; a second communication opening provided below the first blocking means and communicating the first conduit and the second conduit; and a second blocking means provided below the second communication opening for blocking the second conduit.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a refrigerant supply device, a cooling device, and a cooling system. 
       BACKGROUND ART 
       [0002]    With the development of information society in recent years, the amount of data is expected to increase greatly. To respond to the expected increase in the amount of data, it is necessary to install many high-performance servers and other electronic devices. Generally, high-performance electronic devices consume a large amount of electric power. And most of the electric power consumption of the electronic devices is converted into heat. Therefore, installing high-performance electronic devices cause ambient temperature rising due to their exhaust heat consequently. Particularly, in data centers having many electronic devices such as servers, the electronic devices emit a large amount of heat. In such a case, the electronic devices need to be cooled to maintain their functions, thus the air conditioning system requires a large amount of electric power. Because of that situation, there is a demand for a method of reducing load on the air conditioning of electronic devices. 
         [0003]    As a technique to meet such a demand, there has been devised a method of circulating refrigerant without using a pump by utilizing phase changes of the refrigerant. This technique does not use any power for circulating the refrigerant and is very economical. In addition, by using an insulating refrigerant, short circuits are prevented even when there is a refrigerant leak. Thus, the technique of utilizing phase changes of the refrigerant is very effective for removing heat from servers and other electronic devices in data centers where these devices need to be working constantly. 
         [0004]    Such electronic devices as described above are usually disposed in multiple tiers in a rack when used. In such a case, heat receivers for absorbing heat from the electronic devices are preferably disposed in multiple tiers corresponding to the tiers of electronic devices for higher efficiency. 
         [0005]    A technique for refrigerant supply device for supplying refrigerant evenly among heat receivers disposed in multiple tiers as described above by utilizing force of gravity is disclosed in, for example, PTL 1. This technique employs a liquid distribution mechanism between liquid conduits for supplying liquid phase refrigerant and the heat exchanger. The liquid distribution mechanism is in a shape of container, and a branch conduit through which the refrigerant flows to lower tiers is connected to the liquid distribution mechanism at the same height as the predetermined level of liquid surface of the heat exchanger. When the refrigerant exceeds the predetermined level of liquid surface, the refrigerant overflows to the branch tube and flows down to the liquid distribution mechanism on a lower tier. 
         [0006]    PTL 1 and PTL 2 disclose a configuration in which the liquid distribution mechanism is provided with a float and a valve that moves up and down with the float. In this configuration, when the refrigerant surface goes up to a predetermined level, the valve closes and subsequently the refrigerant flows down to the liquid distribution mechanism on a lower tier. PTL 3 also discloses a related technique. 
       CITATION LIST 
     Patent Literature 
       [0007]    [PTL 1] Japanese Unexamined Patent Application Publication No. H5-312361
 
[PTL 2] Japanese Unexamined Patent Application Publication No. H6-195130
 
       [PTL 3] International Publication No. 2015/087530 
     SUMMARY OF INVENTION 
     Technical Problem 
       [0008]    However, PTL 1 and PTL 2 have problems as the following. 
         [0009]    In PTL 1, the branch conduit is provided on a side of the liquid distribution mechanism to allow the refrigerant to flow down to the liquid distribution mechanism below. In order to allow the refrigerant to flow down from the side, the branch conduit is formed with a bent portion. The bent portion increases the lateral width of the refrigerant supply device. 
         [0010]    Furthermore, with the configurations with a float and valve disclosed in PTL 1 and PTL 2, the float provided inside also increases the lateral width of the liquid distribution mechanism. These configurations also have a problem of making the mechanism of the refrigerant supply device more complicated. 
         [0011]    The present invention has been made in view of the above problems, and an object of the invention is to provide a refrigerant supply device with a small lateral width and a capacity to supply refrigerant evenly among heat receivers disposed in multiple tiers. 
       Solution to Problem 
       [0012]    To address the above-described problems, the refrigerant supply device of the present invention is a refrigerant supply device for distributing, by force of gravity, liquid phase refrigerant to heat receivers disposed in a plurality of tiers, the device including: a first conduit for supplying the refrigerant to the heat receivers; a second conduit provided in parallel with the first conduit; a first aperture provided in the first conduit for supplying the refrigerant to one of the heat receivers; a first blocking means provided below the first aperture for blocking the first conduit; a first communication opening provided above the first aperture and communicating the first conduit and the second conduit; a second communication opening provided below the first blocking means and communicating the first conduit and the second conduit; and a second blocking means provided below the second communication opening for blocking the second conduit. 
       Advantageous Effects of Invention 
       [0013]    The present invention has effects of providing a refrigerant supply device with a small lateral width and a capacity to supply refrigerant evenly among heat receivers disposed in multiple tiers. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a cross-sectional view illustrating a first example embodiment. 
           [0015]      FIG. 2  is a cross-sectional view illustrating a second example embodiment. 
           [0016]      FIG. 3  is a cross-sectional view illustrating a third example embodiment. 
           [0017]      FIG. 4  is a block diagram illustrating a fourth example embodiment. 
           [0018]      FIG. 5A  is a latitudinal plan view of a dual passage tube used in a fifth example embodiment. 
           [0019]      FIG. 5B  is a longitudinal cross-sectional view of the dual passage tube used in the fifth example embodiment 
           [0020]      FIG. 6A  is a cross-sectional view illustrating a process in the fifth example embodiment. 
           [0021]      FIG. 6B  is a cross-sectional view illustrating another process in the fifth example embodiment. 
           [0022]      FIG. 6C  is a cross-sectional view illustrating yet another process in the fifth example embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]    Example embodiments of the present invention will be described below in detail. It should be noted that, although technically preferable limitations are applied to the following example embodiments, it is not intended to limit the scope of the present invention to the following. 
       First Example Embodiment 
       [0024]      FIG. 1  is a cross-sectional view illustrating a first example embodiment. The present example embodiment is a refrigerant supply device for distributing, by force of gravity  10 , liquid phase refrigerant to heat receivers disposed in a plurality of tiers. A refrigerant supply device according to the present example embodiment  100  includes a first conduit  1  for supplying refrigerant to heat receivers, and a second conduit  2  provided in parallel with the first conduit  1  and sharing part of its conduit wall with the first conduit  1 . The first conduit  1  includes a first aperture  4  through which the refrigerant flows to a heat receiver  3  and a first blocking means  5  provided below the first aperture  4  for blocking the first conduit  1 . The refrigerant supply device  100  also includes a first communication opening  6  provided above the first aperture  4  and communicating the first conduit  1  and the second conduit  2 . The refrigerant supply device  100  also includes a second communication opening  7  provided below the first blocking means  5  and communicating the first conduit  1  and the second conduit  2 . The second conduit  2  includes a second blocking means  8  provided below the second communication opening  7  for blocking the second conduit  2 . Herein, “lower”, “lowest”, “below”, “down”, and “downward” should be understood in accordance with the direction of the force of gravity  10 . 
         [0025]    When the liquid phase refrigerant  20  is supplied to the refrigerant supply device according to the present example embodiment  100 , the liquid phase refrigerant  20  flows downward as indicated by the dashed arrow in the drawing. First, the liquid phase refrigerant  20  is blocked by the first blocking means  5 , and flows through the first aperture  4  to a heat receiver  3 . When the heat receiver  3  is filled with the refrigerant, the liquid surface reaches the first communication opening  6  and the refrigerant overflows to the second conduit. This flow is blocked by the second blocking means  8  and the refrigerant flows through the second communication opening  7  to the first conduit  1 . This flow is blocked by the first blocking means  5  on the next tier, and the refrigerant is supplied through the first aperture  4  of the next tier to the heat receiver  3  of the next tier. The liquid phase refrigerant is supplied evenly among the heat receivers disposed in the plurality of tiers by repeating this process. 
         [0026]    As described above, according to the present example embodiment, refrigerant is supplied evenly among heat receivers disposed in a plurality of tiers while using a space no wider than two straight tubes disposed in parallel. Furthermore, this is achieved by a simple structure with apertures and blocked parts at predetermined positions of the conduits. 
       Second Example Embodiment 
       [0027]      FIG. 2  is a cross-sectional view illustrating a present example embodiment. The present example embodiment is a cooling device equipped with the refrigerant supply device  100  of the first example embodiment. Herein, the refrigerant supply device  100  is also referred to as liquid phase tube  30  for the sake of simplicity and in light of its function in the cooling device  200 . 
         [0028]    The cooling device  200  includes a liquid phase tube  30 , heat receivers  3  disposed in a plurality of tiers, and a gas phase tube  40 . The gas phase tube  40  is provided with apertures  41  at positions corresponding to respective heat exhaust ports of the heat receivers  3 , and connected with the heat receivers  3 . Note that the heat receivers  3  used in the present example embodiment is an application of so-called ebullient cooling system, that is, heat is absorbed when the liquid phase refrigerant  20  boils in the heat receivers  3 . The heat receivers  3  need only to be suitable to the ebullient cooling system, and the present example embodiment can be realized regardless of what specific inner structure the heat receivers  3  may have. 
         [0029]    The operation of the cooling device  200  of the present example embodiment will be described below. Upon supplied to the liquid phase tube  30  from above, the liquid phase refrigerant  20  is supplied through the first conduits  1  and then the first apertures  4  to the heat receivers  3 . The liquid phase tube  30  supplies the liquid phase refrigerant  20  evenly among the heat receivers  3  disposed in a plurality of tiers in a similar manner as in the first example embodiment. 
         [0030]    The heat receivers  3  receive heat from heat sources, and the liquid phase refrigerant  20  boils and turns into gas phase refrigerant  21  by undergoing a phase change. This lowers the temperature of the heat receivers  3 . The gas phase refrigerant  21  flows through the apertures  41  into the gas phase tube  40 . In the gas phase tube  40 , the liquid phase refrigerant from the heat receivers moves upward by cubical expansion and buoyancy. Here, the refrigerant need not completely evaporate and a small amount of liquid phase refrigerant  20  may remain in the gas phase refrigerant  21 . The gas phase refrigerant  21  is then cooled in a radiator not shown and flows back to the liquid phase tube  30 . Through this cycle, cooling of the heat sources is achieved without using external power. 
         [0031]    As described above, the present example embodiment enables a configuration of a cooling device that supplies liquid phase refrigerant evenly among heat receivers on a plurality of tiers and performs an efficient cooling of heat sources. 
       Third Example Embodiment 
       [0032]      FIG. 3  is a cross-sectional view illustrating a third example embodiment. The present example embodiment provides a configuration example of the cooling device  200  applied to a heat receiver  3  on the lowest tier. At the end  30   a  of the liquid phase tube  30  on the lowest tier, the first conduit  1  and the second conduit  2  are both blocked. The end  40   a  of the gas phase tube  40  is also blocked. It is not necessary to provide a first communication opening  6  at the lowest tier of the liquid phase tube  30  because the liquid phase refrigerant  20  need not be supplied further downward. 
         [0033]    The lowest tier of the liquid phase tube  30  supplies the liquid phase refrigerant  20  to the heat receiver  3  of the lowest tier, and the lowest tier of the gas phase tube  40  receives the gas phase refrigerant from the heat receiver  3  of the lowest tier. Together with the radiator not shown, a closed circuit cooling system is thus formed. 
         [0034]    As described above, the present example embodiment enables a circuit cooling system to be formed with a simple structure. 
       Fourth Example Embodiment 
       [0035]      FIG. 4  is a block diagram illustrating a fourth example embodiment. The present example embodiment provides a configuration example of a cooling system  300  provided with a cooling device according to the second or third example embodiment. In the drawing, flows of the liquid phase refrigerant  20  and the gas phase refrigerant  21  are schematically illustrated. The liquid phase tube  30  is connected with a radiator  50  by a liquid phase conduit  31 . The gas phase tube  40  is connected with the radiator  50  by a gas phase conduit  42 . The liquid phase tube  30  and the gas phase tube  40  are connected with the plurality of heat receivers  3  and form a circuit type cooling system  300 . 
         [0036]    The operation of the cooling system  300  will be described below, starting from the radiator  50 . First, liquid phase refrigerant is supplied from the radiator  50  to the liquid phase conduit  31  and then to the liquid phase tube  30 . The liquid phase refrigerant  20  is supplied evenly among the heat receivers  3  from the liquid phase tube  30  in a manner similar to the first example embodiment. The flow of the liquid phase refrigerant  20  is indicated by the solid arrow.  FIG. 5  illustrates an example with four heat receivers  3 , but naturally the number of the heat receivers  3  is not limited thereto. 
         [0037]    The liquid phase refrigerant  20  boils in the heat receivers  3  and turns to the gas phase refrigerant  21 . The heat receivers  3  are cooled by this phase change and absorb heat from the heat sources. This process is schematically illustrated by bubbles and dashed arrows in  FIG. 5 . The gas phase refrigerant  21  then flows to the gas phase tube  40 , and returns through the gas phase conduit  42  to the radiator  50 . The gas phase refrigerant then returns to a liquid phase by releasing heat and is supplied to the liquid phase conduit  31  again. 
         [0038]    As described above, the present example embodiment enables a cooling system in which refrigerant is supplied evenly among a plurality of heat receivers to be easily constructed. 
       Fifth Example Embodiment 
       [0039]    The present example embodiment relates to a manufacturing method of the refrigerant supply device.  FIGS. 5A and 5B  are a plan view and a cross-sectional view of a dual passage tube used for production of the refrigerant supply device.  FIG. 5A  is a latitudinal plan view. As illustrated in the drawing, in the present example embodiment, a dual passage tube  60  having a passageway  61  and a passageway  62  is used.  FIG. 5B  is a longitudinal cross-sectional view. As illustrated in the drawing, this tube is a straight tube having two passageways. This type of dual passage tube  60  may be produced by, for example, extrusion. It also may be produced by piercing and rolling, reducing rolling, presswork and welding or the like. Methods for manufacturing the dual passage tube  60  are not particularly limited but, to avoid any leakage, there should be no defects such as a void on the conduit wall. 
         [0040]      FIGS. 6A, 6B, and 6C  are cross-sectional views illustrating the manufacturing method of the refrigerant supply device. First, as illustrated in  FIG. 6A , a straight dual passage tube  60  with passageways  61 ,  62  is made ready for processing. 
         [0041]    Next, as illustrated in  FIG. 6B , apertures  63  and communication openings  64  are formed at predetermined positions. 
         [0042]    Next, as illustrated in  FIG. 6C , plugs  65  are provided at positions where the conduits should be blocked, and lids  66  are provided for apertures  63  located outwardly at positions corresponding to the communication openings  64 . The apertures  63  to be connected with the heat receivers are provided with ports  67  for the connection with the heat receivers, while the end of the dual passage tube  60  to be connected with the liquid phase conduit is provided with a port  68 . Depending on the manners of connection with the heat receivers and connection conduits, ports  67 ,  68  may be unnecessary. The lower end of the dual passage tube  60  is provided with a lid  69 . Thus the manufacturing of the refrigerant supply device is complete. 
         [0043]    As described above, simply by forming apertures in a dual passage tube and providing plugs and other members, the refrigerant supply device can be manufactured. 
         [0044]    Hereinabove, the present invention has been described using the above-described example embodiments as exemplary examples. The present invention, however, is not limited to the above-described example embodiments. In other words, various aspects that can be recognized by those skilled in the art can be applied to the present invention within the scope of the invention. 
         [0045]    This application claims priority based on Japanese Patent Application No. 2014-212152, filed Oct. 17, 2014, the disclosure of which is incorporated herein by reference in its entirety. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  first conduit 
           2  second conduit 
           3  heat receiver 
           4  first aperture 
           5  first blocking means 
           6  first communication opening 
           7  second communication opening 
           8  second blocking means 
           10  force of gravity 
           20  liquid phase refrigerant 
           21  gas phase refrigerant 
           30  liquid phase tube 
           31  liquid phase conduit 
           40  gas phase tube 
           41  aperture 
           42  gas phase conduit 
           50  radiator 
           60  dual passage tube 
           61 ,  62  passageway 
           63  aperture 
           64  communication opening 
           65  plug 
           66 ,  69  lid 
           67 ,  68  port 
           100  refrigerant supply device 
           200  cooling device 
           300  cooling system