JP2018054199A - Heat storage tank and air conditioning system with heat storage tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an effective utilization of cold water accumulated in a heat storage tank.SOLUTION: A heat storage tank 40 comprises an outer wall 41 partitioning an inner space against an external part; a supply pipe 67 passing through the outer wall 41 and passed to the inner space to be opened upward for supplying water into the inner space; a discharge pipe 69 passing through a part of the outer wall 41 and passed to the inner space to be opened downward for discharging water in the inner space; a first distributor 67b connected to an upward-directed opening 67a of the supply pipe 67 to reduce a speed of water flowing from the supply pipe 67 into the inner space; a second distributor 69b connected to a downward-directed opening 69a of the discharge pipe 69; and a shield plate 51 extending from an inner surface of the outer wall 41 toward an inside of the inner space so as to direct flow of water flowing from the upper part of the inner space to downward in an inward direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a heat storage tank and an air conditioning system using the heat storage tank.

  The data center is equipped with an air conditioning system that cools air so that installed devices such as servers do not rise above a certain temperature. The air conditioning system cools air by exchanging heat with circulating water. The air conditioning system includes a refrigerator, cools water heated by heat exchange with the refrigerator, and uses the cooled water again for heat exchange. The refrigerator cools water to, for example, a temperature of 7 [° C.]. The cold water of 7 [° C.] is heated to, for example, 12 [° C.] by heat exchange with the air of the air conditioning system. Then, the warmed water is returned to the refrigerator and cooled again to 7 [° C.].

  Here, the air conditioning system includes a heat storage tank on the downstream side of the refrigerator. This heat storage tank is designed to be able to supply 7 [deg.] C. cold water to the secondary side (heat exchanger) for a preset time when the refrigerator is stopped due to unforeseen circumstances such as a power failure. Is. That is, during normal operation, cold water of 7 [° C.] supplied from the refrigerator flows in and is stored in the internal space, and the stored internal cold water flows out and is supplied to the secondary side. .

  The refrigerator and the pump are stopped at the time of a power failure, but after a predetermined time, the refrigerator and the pump are restarted by the emergency power source. However, the refrigerating machine immediately after restarting cannot immediately supply cold water of 7 [° C.] as in steady operation. That is, for a while after the restart, water having a temperature higher than 7 [° C.] is supplied to the heat storage tank. Since the 7 [° C] chilled water that had flowed in before the power failure was stored in the heat storage tank, the stored 7 [° C] chilled water was stored after the restart of the pump even in the event of a power failure. It can supply to the next side (for example, refer patent document 1).

Japanese Patent Laid-Open No. 2006-070579

  By the way, by restarting the pump, water having a temperature higher than 7 [° C.] flows into the heat storage tank from the refrigerator. In the case of a thermal stratification type heat storage tank, relatively high temperature water flows into the upper part of the heat storage tank, and cold water stored in the lower temperature heat storage tank flows out from the lower part of the heat storage tank to the secondary side. However, inside the heat storage tank, the high temperature water and the cold water are in a state of being layered up and down. And as time passes, the cold water in the lower part decreases, but if the layers of water with different temperatures are disturbed by the flow of hot water flowing into the upper part, the cold water mixes with the hot water and the temperature rises. Even though cold water still remains, high temperature water goes around to the lower side, and high temperature water begins to flow out. That is, the cold water accumulated in the heat storage tank cannot be taken out effectively.

  This invention is made | formed in view of the said situation, and it aims at providing the air conditioning system using the thermal storage tank and thermal storage tank which can utilize the cold water collected in internal space effectively.

  According to a first aspect of the present invention, an outer wall that partitions the inner space from the outside, a supply pipe that passes through the outer wall and passes through the inner space and opens upward, and supplies water to the inner space, A drain pipe that passes through a part of the internal space and opens downward, and discharges water in the internal space, and is connected to the upward opening of the supply pipe. A first distributor for reducing the speed of water flowing into the internal space; and a second distributor connected to the downward opening of the discharge pipe, the inner space extending from the inner surface of the outer wall. It is a heat storage tank in which a shielding plate for inwardly directing the flow of water flowing downward from the upper part of the internal space along the inner surface extends toward the inner side.

According to a second aspect of the present invention, a heat exchanger that exchanges heat between water and air, a refrigerator that cools and discharges the supplied water, and water is supplied to the internal space and stored in the internal space. A heat storage tank from which water is discharged, a pump for conveying water, a return pipe connecting the heat exchanger and the refrigerator, a supply pipe connecting the refrigerator and the heat storage tank, and the heat storage tank A discharge pipe connecting the pump, a forward pipe connecting the pump and the heat exchanger, a branch pipe branched from the discharge pipe to the return pipe, and a bypass connecting the supply pipe and the pump 5. A controller for controlling the flow of water in the discharge pipe, the branch pipe, and the bypass pipe, and the heat storage tank is the heat storage tank according to claim 1. The controller is
(1) In a state of steady operation, the water flow in the discharge pipe is allowed, the water flow in the branch pipe and the water flow in the bypass pipe are stopped,
(2) After a power failure, the state is set in advance corresponding to the fact that the water stored in the heat storage tank in the steady operation state cannot be discharged from the heat storage tank to the discharge pipe after returning from the power failure state. When a predetermined time has passed, the flow of water from the discharge pipe to the pump is stopped, and the flow of water in the branch pipe and the flow of water in the bypass pipe are allowed from the discharge pipe,
(3) When the predetermined time has elapsed and the temperature of the water discharged from the refrigerator is lowered to the temperature of the water discharged in the steady operation state, and in the heat storage tank, In a state filled with water at a temperature discharged from the refrigerator, the water flow from the discharge pipe to the pump is allowed, and the water flow in the branch pipe and the water in the bypass pipe are allowed. It is an air conditioning system using a heat storage tank that is controlled to stop the flow.

  According to the heat storage tank and the air conditioning system using the heat storage tank according to the present invention, cold water accumulated in the internal space of the heat storage tank can be used effectively.

It is a perspective view which shows the thermal storage tank which is one Embodiment of this invention. It is a perspective view which shows the baffle plate with which the shielding board provided in the thermal storage tank shown in FIG. 1 and the perforated board were integrated. It is a schematic diagram which shows the cross section of a thermal storage tank, and shows the flow of the water in internal space. It is a schematic diagram which shows temperature distribution in the internal space of the thermal storage tank of Example 1 in 180 [seconds] after starting to supply relatively high-temperature water under a predetermined condition. It is a schematic diagram which shows distribution of the temperature in the internal space of the heat storage tank of the comparative example 180 seconds after it starts supplying relatively hot water on predetermined conditions. It is a graph which shows the distribution of the height position of the water layer of each temperature corresponding to the elapsed time after the relatively high temperature water began to flow into the internal space of the heat storage tank of Example 1. It is a graph which shows distribution of the height position of the water layer of each temperature corresponding to the elapsed time after relatively high temperature water began to flow into the internal space of the heat storage tank of a comparative example. This is a graph in which the elapsed time from the start of supplying relatively hot water to the internal space is set on the horizontal axis and the water temperature at the outlet of the discharge pipe is set on the vertical axis, and the water temperature is plotted for each elapsed time. The solid line graph indicates the heat storage tank of Example 1, and the broken line graph indicates the heat storage tank of the comparative example. Example 2 (one-dot chain line) in which the width W1 of the shielding plate in the heat storage tank of Example 1 is changed to 450 [mm] and the width W2 of the porous plate to 500 [mm], and the width W1 of the shielding plate is 600 [mm]. FIG. 7 is a graph corresponding to FIG. 6 showing Example 3 (fine broken line (dotted line)) in which the width W2 of the porous plate was changed to 350 [mm] and a comparative example (coarse broken line). In Example 4 (one-dot chain line) in which the width W1 of the shielding plate in the heat storage tank of Example 1 is changed to 150 [mm] and the width W2 of the porous plate is changed to 800 [mm], there is no shielding plate and only the porous plate is provided. Then, Comparative Example 2 (fine broken line (dotted line)) in which the width W2 of the porous plate was 950 [mm] and Comparative Example 1 (coarse broken line) which is a comparative example in FIG. It is a graph. Example 5 in which the outer diameter of the outer wall in the heat storage tank of Example 1 was reduced (0.75 times), the width W1 of the shielding plate was changed to 225 [mm], and the width W2 of the porous plate was changed to 488 [mm] ( FIG. 7 is a graph corresponding to FIG. 6 showing a solid line) and a comparative example (coarse broken line) having the same outer diameter as that of Example 5. FIG. Example 6 in which the outer diameter of the outer wall in the heat storage tank of Example 1 was increased (1.5 times), the width W1 of the shielding plate was changed to 450 [mm], and the width W2 of the porous plate was changed to 975 [mm] ( FIG. 7 is a graph corresponding to FIG. 6 showing a solid line) and a comparative example (coarse broken line) having the same outer diameter as that of Example 6. FIG. It is a schematic diagram which shows the structure of the air conditioning system using the thermal storage tank shown in FIG. It is a schematic diagram which shows the flow of the water at the time of the steady operation of an air conditioning system. It is a schematic diagram which shows the flow of water immediately after generation | occurrence | production of the power failure of an air conditioning system. It is a schematic diagram which shows the flow of water after progress of predetermined time from the power failure generation | occurrence | production of an air conditioning system.

  Hereinafter, specific embodiments of the heat storage tank and the air conditioning system using the heat storage tank according to the present invention will be described in detail with reference to the drawings.

<Configuration of heat storage tank>
FIG. 1 is a perspective view showing a heat storage tank 40 which is an embodiment of a heat storage tank according to the present invention, FIG. 2 is a perspective view showing a rectifying plate 50 provided in the heat storage tank 40 shown in FIG. 1, and FIG. It is a schematic diagram which shows the cross section of the tank 40 and shows the flow of the water in internal space. The illustrated heat storage tank 40 is a sealed heat storage tank, and has an outer dimension of about 2600 [mm] in diameter and 2470 [mm] in height, for example, and the amount of water stored in the internal space is about 10 [t]. A heat storage tank of this size is generally small.

  The illustrated heat storage tank 40 includes an outer wall 41, a supply pipe 67, a discharge pipe 69, a supply-side distributor 67b (first distributor), a discharge-side distributor 69b (second distributor), and a rectifying plate 50. I have. The outer wall 41 is a partition wall that partitions the internal space of the heat storage tank 40 from the outside, and the outer shape is substantially cylindrical.

  The supply pipe 67 is a pipe that supplies water 90 to the internal space of the heat storage tank 40. As shown in FIG. 3, the supply pipe 67 passes through a peripheral wall serving as a side surface of the outer wall 41 and passes through the internal space. And the opening 67a of the edge part of the supply piping 67 by the side arrange | positioned in internal space has faced the upper direction of internal space.

  The discharge pipe 69 is a pipe that discharges the water 90 stored in the internal space of the heat storage tank 40 to the outside. The discharge pipe 69 passes through the peripheral wall of the outer wall 41 and passes through the internal space. And the opening 69a of the edge part by the side arrange | positioned in internal space of the discharge piping 69 has faced the downward direction of internal space. In the heat storage tank 40 of the present embodiment, the portion of the outer wall 41 through which the supply pipe 67 penetrates and the portion of the outer wall 41 through which the discharge pipe 69 penetrates the central axis of the outer wall 41 extending in the vertical direction. The positions are opposite to each other. In addition, the part in the surrounding wall of the outer wall 41 which the supply piping 67 penetrated, and the part in the surrounding wall of the outer wall 41 which the discharge piping 69 penetrated are not limited to the mutually opposing position.

  Both the opening 67a of the supply pipe 67 and the opening 69a of the discharge pipe 69 are located on the central axis of the outer wall 41 extending in the vertical direction. The supply side distributor 67 b is connected to the opening 67 a of the supply pipe 67. The supply-side distributor 67b has a bottomed cylindrical case 67c formed with an inner diameter d2 (for example, 700 [mm]) larger than the inner diameter d1 (for example, 250 [mm]) of the supply pipe 67, and the case 67c. It consists of two perforated plates 67d, 67d installed inside. A hole corresponding to the opening 67a of the supply pipe 67 is formed in the bottom plate of the case 67c, and the inside of the supply pipe 67 and the case 67c are connected via the opening 67a of the supply pipe 67 and the hole of the bottom plate of the case 67c. The inside communicates. The upper end of the case 67 c forms an opening 67 e that opens toward the top plate of the outer wall 41 of the heat storage tank 40.

  Each of the perforated plates 67d is a thin plate formed in a circular shape having the same outer diameter as the inner diameter d2 of the case 67c. In the porous plate 67d, for example, a large number of holes having a diameter of 8 [mm] are uniformly formed at intervals of 12 [mm] (opening ratio: 40 [%]). The two perforated plates 67d and 67d are arranged inside the case 67c so as to be lined up and down in two stages with a space therebetween.

  The supply-side distributor 67b has a low speed (for example, 0.755 [m / s]) flowing through the supply pipe 67 when flowing into the internal space of the heat storage tank 40 by the structure described above. For example, the function of reducing to 0.096 [m / s]) is exhibited. Moreover, the porous plate 67d also exhibits the effect of equalizing the distribution of water flowing into the internal space of the heat storage tank 40 to the entire width of the opening 67e of the case 67c.

  The discharge side distributor 69b has the same structure as the supply side distributor 67b. That is, the discharge side distributor 69b is connected to the opening 69a of the discharge pipe 69, and the discharge side distributor 69b has an inner diameter d4 (for example, 700 [mm]) larger than the inner diameter d3 (for example, 250 [mm]) of the discharge pipe 69. The bottomed cylindrical case 69c is formed by two cylindrical plates 69d and 69d. A hole corresponding to the opening 69a of the discharge pipe 69 is formed in the top plate of the case 69c, and the inside of the discharge pipe 69 and the case are formed through the opening 69a of the discharge pipe 69 and the hole of the top plate of the case 69c. 69 c communicates with the inside. The lower end of the case 69 c forms an opening 69 e that opens toward the bottom plate of the outer wall 41 of the heat storage tank 40.

  The perforated plate 69d is the same as the perforated plate 67d. For example, a large number of holes having a diameter of 8 [mm] are uniformly formed at intervals of 12 [mm] (opening ratio 40 [%]). 69d and the case 69c are arranged in two upper and lower rows at intervals. The discharge-side distributor 69b has the above-described structure, and the speed of water flowing from the internal space of the heat storage tank 40 into the opening 69e of the discharge-side distributor 69b is set to the speed of water when flowing through the discharge pipe 69 (for example, 0. 0. 755 [m / s]), a function of decelerating to a lower speed (for example, 0.096 [m / s]) is exhibited.

  As shown in FIG. 2, the rectifying plate 50 includes a shielding plate 51 and a porous plate 52. Specifically, the rectifying plate 50 has a structure in which the shielding plate 51 and the porous plate 52 are formed in a part of a single disc (a circular hole 50a is formed in the center). In other words, the outer peripheral portion of the single disk functions as the shielding plate 51, and the inner portion of the single disk that functions as the shielding plate 51 functions as the porous plate 52.

  The shielding plate 51 is formed in an annular shape with a width W1 from the outer peripheral edge 51a to the inner peripheral edge 51b of, for example, 300 [mm]. In the state of the heat storage tank 40 shown in FIG. 3, the shielding plate 51 has an outer peripheral edge 51 a joined to the inner surface of the outer wall 41. The shielding plate 51 has an inner peripheral edge 51b that becomes a boundary with the porous plate 52 extending toward the inside of the internal space. The shielding plate 51 is applied to the water flowing downward (indicated by an arrow in FIG. 3) along the inner surface of the outer wall 41 from the upper part of the internal space of the heat storage tank 40, and the direction of the water hitting the shielding plate 51 is changed to the internal direction. Change inside the space.

  The perforated plate 52 is formed in an annular shape with a width W2 from the outer peripheral edge 52a to the inner peripheral edge 51b as the outer edge of the hole 50a, for example, 650 [mm]. In the porous plate 52, for example, a large number of holes 54 having a diameter of 8 [mm] are uniformly formed at intervals of 12 [mm] (opening ratio 40 [%]). The perforated plate 52 extends from the outer peripheral edge 52a serving as a boundary with the shielding plate 51 toward the inside of the internal space. In the state of the heat storage tank 40 shown in FIG. 3, the inner peripheral edge 52b of the porous plate 52 is joined to the outer peripheral surface of the supply side distributor 67b. The porous plate 52 has a distribution of water when the water in the portion above the rectifying plate 50 in the internal space of the heat storage tank 40 moves to the portion below the rectifying plate 50, and the holes 54 of the porous plate 52 Equalize the entire formed area.

<Operation of heat storage tank>
According to the heat storage tank 40 of the embodiment configured as described above, the internal space of the heat storage tank 40 is filled with water 90B having a temperature of, for example, 7 ° C. (hereinafter referred to as cold water 90B). When water 90A having a temperature higher than that of the cold water 90B, for example, 12 [° C.] (hereinafter referred to as relatively high temperature water 90A) flows into the internal space through the supply pipe 67, the inside of the supply pipe 67 The relatively high-temperature water 90A that has flowed has a lower flow rate and a wider distribution than the flow rate when passing through the inside of the supply pipe 67 by the supply-side distributor 67b, and from the opening 67e to the upper part of the internal space. Flows in.

  The relatively high-temperature water 90A that has flowed into the internal space has a lower specific gravity because it has a higher temperature than the cold water 90B, rises in the internal space, hits the inner surface of the top plate of the outer wall 41, and as shown by the arrows in FIG. It flows along the inner surface of the top plate toward the periphery (radially outward). From the supply pipe 67, the relatively high temperature water 90A continuously flows into the internal space, the relatively high temperature water 90A accumulates in the upper part of the internal space, and the cold water 90B is pushed under it. A layer is formed depending on the height of the.

  The relatively hot water 90 </ b> A that is continuously supplied flows from the center of the top plate toward the outside in the radial direction, and further flows downward along the inner surface of the peripheral wall of the outer wall 41. For this reason, the relatively hot water 90A supplied is more likely to descend at the outer peripheral portion than at the central portion of the internal space. In this case, the boundary between layers due to high and low temperatures is disturbed, and even in the internal space, even at the same height position, the temperature is low in the central portion in the radial direction, and the temperature becomes higher as it approaches the outer periphery.

  However, since the heat storage tank 40 of this embodiment has the shielding plate 51 disposed on the inner surface of the outer wall 41 in the upper part of the inner space (the height position where the supply-side distributor is disposed), the inner surface of the outer wall 41 The relatively hot water 90A that tends to flow downward along the line hits the upper surface of the shielding plate 51 and flows toward the inside (radial center) of the internal space. Then, it flows downward through a large number of holes 54 (see FIG. 2) that are uniformly formed in the porous plate 52 disposed inside the shielding plate 51.

  At this time, the relatively hot water 90 </ b> A flows downward in a uniform distribution over the entire surface of the porous plate 52. Therefore, the temperature layer is less likely to cause a difference in the radial direction and less likely to be disturbed. That is, in the heat storage tank 40 of the present embodiment, at the same height position in the internal space, the temperature difference is small between the central portion and the outer peripheral portion in the radial direction. As a result, it is prevented or suppressed that the outer peripheral portion of the internal space is filled with relatively hot water 90A preceding the central portion.

  On the other hand, in the conventional heat storage tank that is not the present invention, the outer peripheral portion of the inner space is preceded by the central portion and is filled with relatively hot water 90A, and the relatively hot water 90A is the bottom plate of the outer wall 41. This relatively hot water 90A flows into the discharge-side distributor 69b prior to the cold water 90B still remaining in the central portion of the internal space. For this reason, although the cold water 90B is sufficiently left in the heat storage tank 40, relatively hot water 90A may flow through the discharge pipe 69, which may hinder the heat exchange on the secondary side. is there.

  On the other hand, in the heat storage tank 40 of the embodiment, the outer peripheral portion of the internal space is prevented or suppressed from being filled with the relatively high-temperature water 90A in advance of the center portion, and therefore is relatively ahead of the cold water 90B. Therefore, it is difficult for the hot water 90A to flow into the discharge side distributor 69b. Therefore, the heat storage tank 40 can effectively use the cold water 90B accumulated in the internal space. Thereby, the time which takes out the cold water 90B can be lengthened, without enlarging the size of the thermal storage tank 40. FIG.

  Further, in the heat storage tank 40 of the present embodiment, the shielding plate 51 is formed in an annular shape that is connected over the entire inner surface of the outer wall 41. The effect of suppressing the disturbance of the temperature layer between the cold water 90B and the relatively hot water 90A is high.

  Although the shielding board 51 in this embodiment is formed in the annular | circular shape connected over the perimeter of the inner surface of the outer wall 41, the shielding board in the thermal storage tank of this invention is not limited to this structure. That is, the shielding plate in the heat storage tank of the present invention may be disposed only on a part of the entire circumference of the inner surface of the outer wall 41. Thus, even with a configuration in which the shielding plate is arranged only in a part of the entire circumference of the inner surface of the outer wall 41, about a part of the water that flows downward from the upper part of the inner space along the inner surface of the outer wall, The direction of the flow can be changed to the inside of the internal space, and there is an effect of suppressing the temperature stratification of water from being disturbed.

  Moreover, since the porous plate 52 is arrange | positioned in the part inside the inner peripheral edge 51b of the shielding board 51, the heat storage tank 40 of this embodiment is relatively high in the flow directed inward by the shielding board 51. 90 A of water can be made to flow downward in a uniform distribution over the entire surface of the porous plate 52. Therefore, the temperature layer below the porous plate 52 can be made more difficult to be disturbed.

  In addition, although the thermal storage tank 40 of this embodiment is provided with both the shielding board 51 and the porous plate 52, the thermal storage tank which concerns on this invention is not limited to this form, and is provided with the shielding board 51 at least. It only has to be.

Moreover, since the inner peripheral edge 52b of the porous plate 52 is joined to the outer peripheral surface of the case 67c of the supply side distributor 67b, the heat storage tank 40 of this embodiment ensures a stable support state in the internal space of the heat storage tank 40. can do.

  In addition, the heat storage tank which concerns on this invention is not limited to this form, The porous plate 52 does not need to be joined to the outer peripheral surface of the case 67c of the supply side distributor 67b.

Further, in the heat storage tank 40 of the present embodiment, since the shielding plate 51 is disposed at a position lower in the height direction than the position of the opening 67e of the supply side distributor 67b, the heat storage tank 40 is located above the opening 67e of the supply side distributor 67b. It is possible to reliably prevent the relatively hot water 90A flowing into the internal space from hitting the shielding plate 51 when flowing upward, and to prevent the temperature layer from being disturbed. be able to.

  In addition, the shielding plate in the heat storage tank according to the present invention may be disposed at a position higher in the height direction than the position of the opening 67e of the supply side distributor 67b, or a position having the same height as the position of the opening 67e. May be arranged.

<Example of analysis>
Hereinafter, with respect to the heat storage tank 40 (Example 1) of the present embodiment, the change in the temperature distribution of the internal space over time is compared with a conventional heat storage tank (comparative example) that does not have the rectifying plate 50 and numerical fluid analysis (CFD). An analysis example compared by this method will be described below.

The heat storage tank has the following specifications for both Example 1 and Comparative Example. That is, the amount of water stored in the internal space (heat storage tank capacity V) is 10 [m ³ ] with external dimensions of a diameter of 2600 [mm] and a height of 2470 [mm]. The inner diameters d1 and d3 of the supply pipe 67 and the discharge pipe 69 are 250 [mm], respectively. The inner diameters d2 and d4 of the supply side distributor 67b and the discharge side distributor 69b are 700 [mm], respectively. Each of the two perforated plates 67d and 69d provided in each distributor 67b and 69b has a uniform number of holes each having a diameter of 8 [mm] at intervals of 12 [mm] (opening ratio of 40 [%]). Yes.

  The specification of the rectifying plate 50 provided only in the heat storage tank 40 of the first embodiment is as follows. That is, the width W1 of the shielding plate 51 is 300 [mm], the width W2 of the porous plate 52 is 650 [mm], and the holes 54 having a diameter of 8 [mm] are formed in the porous plate 52 at intervals of 12 [mm] (opening). Many are uniformly formed at a rate of 40%.

And the internal space of the heat storage tank 40 of Example 1 and the internal space of the heat storage tank of the comparative example are each filled with cold water 90B having a temperature of 7 [° C.] in advance. Then, relatively hot water 90A having a temperature of 12 [° C.] (utilization temperature difference Δθ = 5 [° C.]) is supplied into the internal space of the heat storage tank through the supply pipe 67, with an average speed of 0.755 [m / s] Supplied with. At this time, the flow rate Q of the water supplied to the heat storage tank is 0.037 [m ³ / s] (= 2, 222 [L / min]).

Under this condition, the heat storage tank efficiency η is calculated by the following equation.

  FIG. 4A is a schematic diagram showing a temperature distribution in the internal space of the heat storage tank 40 of Example 1 at 180 [seconds] after starting to supply relatively hot water 90A under the above conditions, and FIG. It is a schematic diagram which shows temperature distribution in the internal space of the heat storage tank of the comparative example 180 seconds after starting to supply high-temperature water 90A on the said conditions. The numerical value in the figure represents the temperature of water, which is a gray scale from the white part to black, and indicates that the temperature increases as it approaches black. In the figure, the highest temperature is 12 [° C.], which is the temperature of the relatively hot water 90A that flows in, and the lowest temperature is 7 [° C., which is the temperature of the cold water 90B previously stored in the internal space. ].

  As understood from FIGS. 4A and 4B, the heat storage tank 40 of Example 1 is formed without disturbing the temperature layer over the entire internal space, and even when 180 [seconds] have elapsed. A sufficient amount of cold water 90B is distributed throughout the lower part of the internal space including the periphery of the discharge port on the discharge pipe 69 side (the portion where the discharge side distributor 69b (see FIG. 3) is disposed) The cold water 90 </ b> B can be discharged through the discharge pipe 69.

  On the other hand, in the heat storage tank of the comparative example, the portion along the inner surface of the outer wall 41 in the inner space forms a layer whose temperature has risen ahead of the central portion, and when 180 [seconds] has passed, The temperature of the cold water 90 </ b> B is mixed with the relatively hot water 90 </ b> A, and the temperature of the cold water 90 </ b> B exceeds 7 [° C.].

  When the heat storage tank efficiency η is 100 [%], which is an ideal state, the cold water 90B can be taken out after 270 [seconds] from the start of supplying relatively hot water 90A under the above conditions. As the time during which the cold water 90B can be taken out is closer to 270 [seconds], the heat storage tank efficiency η is closer to ideal. And at the time of 180 [second] progress, since the heat storage tank 40 of Example 1 can take out cold water 90B, and the heat storage tank of a comparative example cannot take out cold water 90B, Example 1 is compared with a comparative example. It has been proved that the heat storage tank efficiency η is high and the cold water 90B accumulated in the internal space of the heat storage tank can be used effectively.

  FIG. 5A is a graph showing the distribution of the height position of the water layer at each temperature corresponding to the elapsed time since the relatively hot water 90A started to flow into the internal space of the heat storage tank 40 of the first embodiment. Yes, FIG. 5B is a graph showing the distribution of the height position of the water layer at each temperature corresponding to the elapsed time since the relatively hot water 90A began to flow into the internal space of the heat storage tank of the comparative example. is there. Of the lines in the figure, fine broken lines are thick after 60 [seconds], rough broken lines are 120 [seconds], long and short dashed lines are 180 [seconds], thin solid lines are thick after 240 [seconds]. Solid lines indicate after 300 seconds.

  As is understood from FIGS. 5A and 5B, in the heat storage tank 40 of Example 1, the water layer at each temperature descends in the internal space without being greatly disturbed over time. When 240 [seconds] have elapsed from the second], the cold water 90B of 7 [° C.] reaches the lowermost portion, and the cold water 90B can be discharged through the discharge pipe 69 until that time.

  On the other hand, in the heat storage tank of the comparative example, when the temperature of the water layer at each temperature has passed from 60 [seconds] to 120 [seconds], the cold water 90B of 7 [° C] and the water layer of 8 [° C] are at the bottom. The temperature distribution is greatly disturbed and the period during which the cold water 90B can be discharged by the discharge pipe 69 is significantly shorter than that of the heat storage tank 40 of the first embodiment. Thus, it was proved that the heat storage tank 40 of Example 1 is not particularly disturbed by the water temperature layer in the internal space as compared with the comparative example.

  FIG. 6 shows the time elapsed since the start of supplying relatively hot water 90A to the internal space on the horizontal axis and the water temperature at the outlet of the discharge pipe 69 on the vertical axis. The solid line graph shows the heat storage tank 40 of Example 1, and the broken line graph shows the heat storage tank of the comparative example. In addition, the position of 270 [seconds] on the horizontal axis is the position where the heat storage tank efficiency η is 100 [%]. Therefore, when the heat storage tank efficiency η is 100 [%], the temperature of water at the outlet of the discharge pipe 69 is maintained at 7 [° C.] in the range of 0 to 270 [seconds]. The same applies to FIGS.

  As is understood from FIG. 6, the heat storage tank 40 of the first embodiment can discharge the cold water 90B having a temperature of 7 [° C.] from the discharge pipe 69 until 190 [seconds] has elapsed from 180 [seconds]. On the other hand, the heat storage tank of the comparative example can discharge cold water 90B having a temperature of 7 [° C.] from the discharge pipe 69 until 130 [seconds], but when 130 [seconds] has elapsed, The cold water 90B at 7 [° C.] could not be discharged. Therefore, it was proved that the heat storage tank 40 of Example 1 has improved heat storage tank efficiency η compared to the comparative example, and can discharge the cold water 90B accumulated in the internal space of the heat storage tank over a long time. .

  FIG. 7 shows a second embodiment in which the width W1 of the shielding plate 51 in the heat storage tank 40 of the first embodiment is changed to 450 [mm] and the width W2 of the porous plate 52 to 500 [mm], and the shielding plate 51. 6 corresponding to FIG. 6 showing Example 3 (fine broken line (dotted line)) and a comparative example (coarse broken line) in which the width W1 of the plate was changed to 600 [mm] and the width W2 of the porous plate 52 was changed to 350 [mm]. It is a graph.

  As understood from FIG. 7, the heat storage tank 40 of the second and third embodiments has an elapsed time when the temperature of the water discharged from the discharge pipe 69 exceeds 7 [° C.] from the first embodiment of FIG. 6. Although slightly shorter, virtually no significant difference is observed. In addition, there is no significant difference between Example 2 and Example 3. On the other hand, Example 2 and Example 3 are significantly different from the comparative example as in FIG. From this, the heat storage tank 40 in which the width W1 of the shielding plate 51 is larger than 300 [mm] is not significantly different from the heat storage tank 40 in which the width W1 of the shielding plate 51 is 300 [mm]. Was confirmed.

  8 shows a fourth embodiment (one-dot chain line) in which the width W1 of the shielding plate 51 in the heat storage tank 40 of the first embodiment is changed to 150 [mm] and the width W2 of the porous plate 52 to 800 [mm], and the shielding plate 51. Comparative example 2 (fine broken line (dotted line)) in which only the porous plate 52 is provided and the width W2 of the porous plate 52 is set to 950 [mm], and comparative example 1 (coarse broken line) which is a comparative example in FIG. 7 is a graph corresponding to FIG.

  As understood from FIG. 8, the heat storage tank 40 of the fourth embodiment has a slightly longer elapsed time when the temperature of the water discharged from the discharge pipe 69 exceeds 7 ° C. than the first embodiment of FIG. 6. However, there is virtually no significant difference. On the other hand, in Comparative Example 2, water exceeding 7 [° C.] is discharged around 140 [seconds] as in Comparative Example 1, but thereafter, the temperature rise continues as in Comparative Example 1. Rather, the discharge of water slightly exceeding 7 [° C] continues until about 200 [seconds], and after about 200 [second], the temperature of the discharged water rises from 7 [° C]. Begin to.

  Therefore, although Comparative Example 2 initially shows a tendency similar to that of Comparative Example 1, as a whole, it shows a tendency close to that of Example 4, so that it does not include the shielding plate 51 and is in contact with the inner surface of the outer wall 41. In the heat storage tank in which the perforated plate 52 is disposed, the portion other than the hole 54 of the perforated plate 52 functions as the shielding plate 51 and exhibits the effect of the present invention (improvement of the heat storage tank efficiency η). Therefore, Comparative Example 2 is an embodiment of a heat storage tank according to the present invention.

  FIG. 9 shows that the outer diameter of the outer wall 41 in the heat storage tank 40 of Example 1 is reduced (0.75 times), the width W1 of the shielding plate 51 is 225 [mm], and the width W2 of the porous plate 52 is 488 [mm]. 7 is a graph corresponding to FIG. 6, showing a modified example 5 (solid line) and a comparative example (coarse broken line) having the same outer diameter as that of the example 5. In addition, in accordance with other analysis examples, the flow rate Q of water supplied to the heat storage tank is set to 1, so that the position of 270 [seconds] on the horizontal axis is the position of the heat storage tank efficiency η of 100 [%]. Changed to 250 [L / min].

  As understood from FIG. 9, the heat storage tank 40 of Example 5 is not significantly different from Example 1 shown in FIG. 6. On the other hand, in the comparative example, the elapsed time when the temperature of the water discharged from the discharge pipe 69 exceeds 7 [° C.] has elapsed from 130 [seconds] to 150 [seconds]. A large temperature rise is not observed until about a second]. However, after 200 [seconds], it is recognized that Example 5 is delayed by about 50 [seconds] with respect to the temperature of the water discharged from the discharge pipe 69 as compared with the comparative example. Therefore, it was proved that the present invention exhibits an effect (improvement of heat storage tank efficiency η) as compared with the comparative example even in the heat storage tank having a smaller outer diameter.

  FIG. 10 shows that the outer diameter of the outer wall 41 in the heat storage tank 40 of Example 1 is increased (1.5 times), the width W1 of the shielding plate 51 is 450 [mm], and the width W2 of the porous plate 52 is 975 [mm]. 7 is a graph corresponding to FIG. 6, showing a modified example 6 (solid line) and a comparative example (coarse broken line) having the same outer diameter as that of the example 6. In accordance with other analysis examples, the flow rate Q of water supplied to the heat storage tank is set to 5, so that the position of 270 [seconds] on the horizontal axis is the position of the heat storage tank efficiency η of 100 [%]. 000 [L / min].

  As understood from FIG. 10, in the heat storage tank 40 of Example 6, water slightly exceeding the temperature 7 [° C.] is discharged around 130 [seconds]. As in the first embodiment shown in FIG. 6, the temperature of the discharged water starts to rise around 190 [seconds]. The degree of temperature rise at this time is larger than that of Example 1 shown in FIG. On the other hand, in the comparative example, the water exceeding the temperature 7 [° C.] is discharged around 130 [seconds], and thereafter, the temperature continues to rise as in the comparative example shown in FIG. Therefore, in Example 6, compared with Example 1 shown in FIG. 6, although the degree of temperature rise from around 190 [seconds] is large, the heat storage tank efficiency η is improved compared to the comparative example, and the heat storage It was proved that the cold water 90B accumulated in the internal space of the tank can be discharged over a long time.

<Modification>
In the rectifying plate 50 according to the present embodiment, a shielding plate 51 and a porous plate 52 are formed in a part of a single disc. However, the heat storage tank according to the present invention is not limited to this form, and the shielding plate 51 and the porous plate 52 are not formed by a single plate member, but may be formed by separate members. Good.

  Moreover, although the baffle plate 50 in this embodiment becomes a structure where the shielding plate 51 and the porous plate 52 are arrange | positioned on the same plane, the heat storage tank which concerns on this invention is not limited to this form, and is shielded. The plate 51 and the perforated plate 52 may not be arranged on the same plane.

  Moreover, although the rectifying plate 50 in the present embodiment has a structure in which the shielding plate 51 and the porous plate 52 are integrally formed, the heat storage tank according to the present invention is not limited to this form, and the shielding plate 51. And the porous plate 52 may be separate bodies.

  Moreover, since the hole 50a which penetrates the supply side distributor 67b and the supply piping 67 is unnecessary when the perforated plate in the heat storage tank which concerns on this invention is arrange | positioned below the supply piping 67, it is not circular but circular. It may be formed in a plate shape.

  Moreover, although the heat storage tank 40 which concerns on this embodiment is an example which discharges the cold water 90B of 7 [degreeC] by supplying relatively hot water 90A of 12 [degreeC], the heat storage tank which concerns on this invention is These are not limited to supplying and discharging water 90A and 90B at these temperatures, and may be used for supplying and discharging water at other temperatures. The temperature difference (utilization temperature difference Δθ) is not limited to 5 [° C.] in the present embodiment, and may be a temperature difference larger than this or a temperature difference smaller than this. .

<Configuration of air conditioning system>
FIG. 11 is a schematic diagram showing a configuration of an air conditioning system 100 (hereinafter referred to as an air conditioning system 100) which is an embodiment of an air conditioning system using a heat storage tank according to the present invention. The illustrated air conditioning system 100 is installed in a data center, for example, for use in cooling air so that devices such as servers in the data center do not rise above a certain temperature. However, the air conditioning system according to the present invention is not limited to this application, and may be used for general air conditioning such as air conditioning in a building.

  The illustrated air conditioning system 100 includes a heat exchanger 10, a refrigerator 20, a secondary pump 30, a heat storage tank 40, piping connecting them, a switching valve that opens and closes a passage inside the piping, and a switching valve And a controller 80 for controlling opening and closing.

  The heat exchanger 10 performs heat exchange between water flowing inside the air conditioning system 100 and air inside the data center. The refrigerator 20 discharges the supplied water (for example, relatively hot water 90A having a temperature of 12 [° C.]) as cold water 90B cooled to a temperature of 7 [° C.]. The secondary pump 30 conveys water. In the heat storage tank 40, water is supplied to the internal space, and the water stored in the internal space is discharged. In addition, the thermal storage tank 40 is the thermal storage tank 40 as one Embodiment of the thermal storage tank which concerns on this invention shown in FIG.

  The air conditioning system 100 includes a first return pipe 61, a return header 62, and a second return pipe 63 as return pipes connecting the heat exchanger 10 and the refrigerator 20. The first return pipe 61 is connected to the heat exchanger 10, the second return pipe 63 is connected to the refrigerator, and the return header 62 is between the first return pipe 61 and the second return pipe 63, The second return pipe 63 is connected.

  The air conditioning system 100 includes a first supply pipe 65, a third forward header 66, and a second supply pipe 67 as supply pipes that connect the refrigerator 20 and the heat storage tank 40. The first supply pipe 65 is connected to the refrigerator 20, the second supply pipe 67 is connected to the heat storage tank 40, and the third forward header 66 is between the first supply pipe 65 and the second supply pipe 67, and the first supply pipe 65 65 and the second supply pipe 67 are connected. The second supply pipe 67 is the same as the supply pipe 67 shown in FIG. Therefore, the second supply pipe 67 may be a part of the heat storage tank 40.

  The air conditioning system 100 also includes a first discharge pipe 69, a second forward header 71, and a second discharge pipe 72 as discharge pipes that connect the heat storage tank 40 and the secondary pump 30. The first discharge pipe 69 is connected to the heat storage tank 40, the second discharge pipe 72 is connected to the secondary pump 30, and the second forward header 71 is between the first discharge pipe 69 and the second discharge pipe 72, and the first discharge The pipe 69 and the second discharge pipe 72 are connected. The first discharge pipe 69 is the same as the discharge pipe 69 shown in FIG. Therefore, the first discharge pipe 69 may be a part of the heat storage tank 40.

  In addition, the air conditioning system 100 includes a first forward pipe 74, a first forward header 75, and a second forward pipe 76 as outgoing pipes that connect the secondary pump 30 and the heat exchanger 10. The first forward pipe 74 is connected to the secondary pump 30, the second forward pipe 76 is connected to the heat exchanger 10, and the first forward header 75 is between the first forward pipe 74 and the second forward pipe 76, The forward pipe 74 and the second forward pipe 76 are connected.

  The air conditioning system 100 also includes a branch pipe 70 that connects the first discharge pipe 69 and the return header 62 as a branch pipe that branches from the discharge pipe to the return pipe.

  The air conditioning system 100 also includes a bypass pipe 77 that connects the third forward header 66 and the second forward header 71 as a bypass pipe that connects the supply pipe and the secondary pump 30.

  In addition, the air conditioning system 100 includes a first adjustment pipe 64 that connects the return header 62 and the third forward header 66 as a first adjustment pipe that connects the return pipe and the supply pipe. Further, the air conditioning system 100 includes a second adjustment pipe 73 that connects the second forward header 71 and the first forward header 75 as a second adjustment pipe that connects the discharge pipe and the forward pipe.

  In addition, the air conditioning system 100 serves as a switching valve between the first discharge pipe 69 and the second forward header 71 between the branch part that is downstream of the branch part to which the branch pipe 70 is connected. A discharge switching valve 81 for opening and closing the discharge pipe 69, a branch switching valve 82 for opening and closing the branch pipe 70, a bypass switching valve 83 for opening and closing the bypass pipe 77, an adjustment switching valve 85 for opening and closing the first adjustment pipe 64, And an adjustment switching valve 84 for opening and closing the second adjustment pipe 73. The controller 80 controls opening / closing of the discharge switching valve 81, the branch switching valve 82, the bypass switching valve 83, the adjustment switching valve 84, and the adjustment switching valve 85 according to the operating state of the air conditioning system 100.

<Operation of the air conditioning system>
The air conditioning system 100 configured as described above operates as follows. 12 shows the flow of water during steady operation of the air conditioning system 100, FIG. 13 shows the flow of water immediately after the occurrence of a power failure in the air conditioning system 100, and FIG. 14 shows the flow of water after a predetermined time has elapsed since the occurrence of the power failure of the air conditioning system 100. FIG.

(During steady operation)
First, in the air conditioning system 100, the heat storage tank 40 is preliminarily filled with cold water 90B having a temperature of 7 [° C.]. The air conditioning system 100 is driven in the normal operation state (steady operation) by receiving power from the normal power supply of the data center, and as shown in FIG. While permitting, the water flow in the branch pipe and the water flow in the bypass pipe are stopped. Specifically, the controller 80 controls to open the discharge switching valve 81 and the adjustment switching valves 84 and 85 and close the branch switching valve 82 and the bypass switching valve 83. In the operation described in the present embodiment, the adjustment switching valve 84 is always open. In FIG. 12, the broken line piping indicates that it is closed under the control of the controller. The same applies to the following drawings.

  The air conditioning system 100 sends the water inside the air conditioning system 100 by the operation of the secondary pump 30 so that the pressure is constant in the direction indicated by the arrow. That is, the cold water 90B having a temperature of 7 [° C.] stored in the internal space of the heat storage tank 40 is the first discharge pipe, the second forward header 71, the second discharge pipe 72, the secondary pump 30, and the first forward pipe 74. The first forward header 75 and the second forward pipe 76 are supplied to the heat exchanger 10. The heat exchanger 10 exchanges heat between the air inside the data center and the cold water 90B, and supplies the air cooled by the cold water 90B to the inside of the data center.

  On the other hand, the water heated in the heat exchanger 10 flows to the refrigerator 20 through the first return pipe 61, the return header 62, and the second return pipe 63, and the refrigerator 20 uses the water flowing in from these return pipes. Cool and use cold water 90B at a temperature of 7 [° C.]. The cold water 90 </ b> B cooled by the refrigerator 20 flows into the heat storage tank 40 through the first supply pipe 65, the third forward header 66, and the second supply pipe 67. Thus, the air conditioning system 100 always stores the cold water 90B in the internal space of the heat storage tank 40 while cooling the air in the data center in the heat exchanger 10 during the steady operation. Note that the first adjustment pipe 64 adjusts the amount of water on the upstream side and the downstream side of the refrigerator 20, so that regardless of the operation status of the air conditioning system 100, the return header 62 to the third forward header 66 or the first A flow from the forward header 66 to the return header 62 may occur.

(During power failure)
Next, the operation of the air conditioning system 100 during a power failure will be described. When a power failure occurs, the normal power supply of the data center stops and the supply of power to the air conditioning system 100 stops, so the refrigerator 20 and the secondary pump 30 stop, and immediately after the power failure occurs, as shown in FIG. In addition, only the flow of the first adjustment pipe 64 is obtained.

  In addition to the normal power supply, the data center is equipped with an emergency power supply that operates in place of the normal power supply when the normal power supply stops. After a lapse of time (for example, after 1 [minute]), the emergency power supply is activated and power is supplied to the air conditioning system 100, and the secondary pump 30 and the refrigerator 20 resume operation after recovering from the power failure state. To do. At this time, the flow of water inside the air conditioning system 100 returns to the state of FIG.

  However, immediately after returning from the power failure state, the temperature of the water discharged from the refrigerator 20 is not lowered to the temperature 7 [° C.] of the water discharged during the normal operation. The water flowing through the third forward header 66 and the second supply pipe 67 is water 90A that is relatively hotter than the cold water 90B. Accordingly, the heat storage tank 40 is supplied with relatively hot water 90A.

  Here, since the cold water 90B supplied during the steady operation is stored in the heat storage tank 40, relatively hot water 90A is supplied while the cold water 90B remains in the internal space of the heat storage tank 40. Even in this case, the cold water 90B can be discharged to the first discharge pipe 69. And the cold water 90B discharged | emitted from the thermal storage tank 40 to the 1st discharge piping 69 is supplied to the heat exchanger 10 similarly to the time of steady operation, and can cool the air inside a data center.

(After a predetermined time has elapsed since the occurrence of a power failure)
After returning from the power failure state, a predetermined time elapses from the heat storage tank 40 in accordance with the fact that the cold water 90B stored in the heat storage tank 40 during steady operation cannot be discharged to the first discharge pipe 69. When the air conditioning system 100 stops the flow of water from the first discharge pipe 69 to the secondary pump 30 as shown in FIG. 14, the water flow from the first discharge pipe 69 to the branch pipe 70 and the bypass pipe Allow water flow at 77. Specifically, the controller 80 controls to close the discharge switching valve 81 and the adjustment switching valve 85 and open the branch switching valve 82 and the bypass switching valve 83. Note that the predetermined time set in advance is in the range of 180 [seconds] to 190 [seconds] shown in FIG. 6 as an example, as shown in the analysis example of the heat storage tank 40 described above.

  When this predetermined time has elapsed, the refrigerator 20 has discharged the cold water 90B that has been lowered to a temperature of 7 [° C.] that is discharged during steady operation. Therefore, as shown in FIG. 14, the cold water 90 </ b> B produced by the refrigerator 20 is supplied to the heat storage tank 40 through the first supply pipe 65, the third forward header 66, and the second supply pipe 67, and The heat exchanger 10 passes through the bypass pipe 77, the second forward header 71, the second discharge pipe 72, the secondary pump 30, the first forward pipe 74, the first forward header 75, and the second forward pipe 76 from the three forward header 66. The heat exchanger 10 cools the air inside the data center with the supplied cold water 90B.

  On the other hand, although the cold water 90B is supplied to the heat storage tank 40, relatively hot water 90A supplied from the refrigerator 20 is stored in the internal space of the heat storage tank 40 immediately after returning from the power failure. The relatively hot water 90A discharged from the heat storage tank 40 until the internal space of the heat storage tank 40 is filled with the cold water 90B passes through the first discharge pipe 69 and the branch pipe 70 and returns to the return header. Return to 62. The relatively hot water 90A returned to the return header 62 merges with the water returned to the return header 62 from the heat exchanger 10 through the first return pipe 61, passes through the second return pipe 63, It is sent to the refrigerator 20. By closing the adjustment switching valve 85, the flow of the cold water 90B from the third forward header 66 through the first adjustment pipe 64 to the return header 62 is prevented, and the time for the cold water 90B to be stored in the heat storage tank 40 is shortened. doing.

  Thereafter, when the internal space of the heat storage tank 40 is filled with the cold water 90B, the controller 80 allows the flow of water in the discharge pipe and stops the flow of water in the branch pipe and the water in the bypass pipe. As shown in FIG. 12, the controller 80 controls to open the discharge switching valve 81 and the adjustment switching valve 85 and close the branch switching valve 82 and the bypass switching valve 83.

  According to the air conditioning system 100 configured as described above, air conditioning can be resumed using the cold water 90B stored in the heat storage tank 40 immediately after the power failure is restored. At this time, the heat storage tank 40 can effectively utilize the cold water 90B accumulated in the internal space. Therefore, the air conditioning system 100 can ensure a long delay until the refrigerator 20 returns to the steady state where the cold water 90B starts to be supplied after restarting.

40 heat storage tank 41 outer wall 50 rectifying plate 51 shielding plate 54 hole 67 supply pipe 67a opening 67b supply side distributor 69 discharge pipe 69a opening 69b discharge side distributor 90A relatively high temperature water 90B cold water

Claims (5)

An outer wall that partitions the internal space from the outside,
A supply pipe for supplying water to the internal space, which passes through the outer wall and passes through the internal space and opens upward;
A discharge pipe for discharging the water in the internal space, which passes through a part of the outer wall and passes through the internal space and opens downward;
A first distributor connected to the upward opening of the supply pipe for reducing the speed of water flowing from the supply pipe into the internal space;
A second distributor connected to the downward opening of the discharge pipe,
A heat storage tank in which a shielding plate is disposed extending from the inner surface of the outer wall toward the inside of the inner space and directing the flow of water flowing downward from the upper portion of the inner space along the inner surface. The shielding plate is connected over the entire circumference of the inner surface,
2. The perforated plate having a hole through which water of the flow directed inward by the shielding plate is allowed to pass downward is disposed in a portion inside the inner peripheral edge of the shielding plate. Heat storage tank.   The heat storage tank according to claim 2, wherein an inner peripheral edge of the porous plate is joined to an outer peripheral surface of the first distributor.   4. The heat storage tank according to claim 1, wherein the shielding plate is disposed at a position lower in a height direction than a position of the opening where the first distributor is opened in the internal space. 5. . A heat exchanger that exchanges heat between water and air;
A refrigerator that cools and discharges the supplied water;
A pump for conveying water;
A heat storage tank in which water is supplied to the internal space, and the water stored in the internal space is discharged;
A return pipe connecting the heat exchanger and the refrigerator;
A supply pipe connecting the refrigerator and the heat storage tank;
A discharge pipe connecting the heat storage tank and the pump;
Outward piping connecting the pump and the heat exchanger;
A branch pipe branched from the discharge pipe to the return pipe;
A bypass pipe connecting the supply pipe and the pump;
A controller for controlling the flow of water in the discharge pipe, the branch pipe and the bypass pipe,
The heat storage tank is the heat storage tank according to any one of claims 1 to 4,
The controller is
(1) In a state of steady operation, the water flow in the discharge pipe is allowed, the water flow in the branch pipe and the water flow in the bypass pipe are stopped,
(2) After a power failure, the state is set in advance corresponding to the fact that the water stored in the heat storage tank in the steady operation state cannot be discharged from the heat storage tank to the discharge pipe after returning from the power failure state. When a predetermined time has passed, the flow of water from the discharge pipe to the pump is stopped, and the flow of water in the branch pipe and the flow of water in the bypass pipe are allowed from the discharge pipe,
(3) When the predetermined time has elapsed and the temperature of the water discharged from the refrigerator is lowered to the temperature of the water discharged in the steady operation state, and in the heat storage tank, In a state filled with water at a temperature discharged from the refrigerator, the water flow from the discharge pipe to the pump is allowed, and the water flow in the branch pipe and the water in the bypass pipe are allowed. An air conditioning system using a heat storage tank that controls the flow to stop.