Water dispersion device and water dispersion method

Abstract

This water dispersion device is for cooling a heat exchanger by means of air from which vaporization heat has been drawn in association with the evaporation of water from a water dispersion mat that is wet with water, said water dispersion device comprising: a lower-end detection unit that detects the position of the lower end of a wet region of the water dispersion mat; and a control unit that, on the basis of the position of the lower end of the wet region, adjusts the amount of water supplied to the water dispersion mat.

Description

Technical Field

[0001] The present disclosure relates to a water sprinkling apparatus and a water sprinkling method.Background Art

[0002] Conventionally, a water sprinkling apparatus has been known in which water is dropped on a water sprinkled mat disposed in front of a heat exchanger of a refrigerator and a condensation load is reduced by using air from which heat of evaporation is removed along with evaporation of water from the water sprinkled mat (e.g., see Patent Literature (hereinafter, referred to as PTL) 1). The water sprinkling apparatus described in PTL 1 measures a temperature outside of the water sprinkled mat (side opposite to the heat exchanger with respect to the water sprinkled mat), and supplies water to the water sprinkled mat when the measured temperature is equal to or higher than a set value. JP 6 481936 B2 or JP 2015 210022 A disclose water sprinkling apparatuses according to the preamble of claim 1.Citation ListPatent Literature

[0003] PTL 1 Japanese Patent Application Laid-Open No. 2004-3806Summary of InventionTechnical Problem

[0004] However, with the configuration described in PTL 1, the amount of water to be supplied is adjusted based only on the temperature outside of the water sprinkled mat, and thus, the amount of water discharged downward without evaporating from the water sprinkled mat possibly increases.

[0005] An object of the present disclosure is to provide a water sprinkling apparatus and a water sprinkling method capable of reducing the amount of water discharged downward without evaporating from a water sprinkled mat.Solution to Problem

[0006] A water sprinkling apparatus of the present disclosure is a water sprinkling apparatus for cooling a heat exchanger by air from which heat of evaporation is removed along with evaporation of water from a water sprinkled mat wet with water, and includes: a lower-end detector that detects a position of a lower end of a wet area of the water sprinkled mat; and a controller that adjusts an amount of water supplied to the water sprinkled mat, based on the position of the lower end of the wet area, wherein the lower-end detector includes: an inner dry-bulb temperature detector disposed between the water sprinkled mat and the heat exchanger and detecting a dry-bulb temperature; and a wet-bulb temperature detector disposed at a position opposite to the heat exchanger with respect to the water sprinkled mat and detecting a wet-bulb temperature, and wherein the position of the lower end of the wet area is detected based on a temperature difference between the inner dry-bulb temperature and the wet-bulb temperature.

[0007] A water sprinkling method of the present disclosure is a water sprinkling method performed by a water sprinkling apparatus for cooling a heat exchanger by air from which heat of evaporation is removed along with evaporation of water from a water sprinkled mat wet with water. The water sprinkling apparatus detects a position of a lower end of a wet area of the water sprinkled mat, and adjusts an amount of water supplied to the water sprinkled mat, based on the position of the lower end of the wet area, wherein the detecting includes: detecting, by an inner dry-bulb temperature detector disposed between the water sprinkled mat and the heat exchanger, a dry-bulb temperature; detecting, by a wet-bulb temperature detector disposed at a position opposite to the heat exchanger with respect to the water sprinkled mat, a wet-bulb temperature; and detecting the position of the lower end of the wet area based on a temperature difference between the inner dry-bulb temperature and the wet-bulb temperature.Advantageous Effects of Invention

[0008] According to a water sprinkling apparatus and a water sprinkling method of the present disclosure, it is possible to reduce the amount of water discharged downward without evaporating from a water sprinkled mat.Brief Description of Drawings

[0009] FIG. 1 is a front view of a refrigerant cooling apparatus according to an embodiment; FIG. 2 is a side view of the refrigerant cooling apparatus according to the embodiment; FIG. 3 is a block diagram illustrating a control system of a water sprinkling apparatus according to the embodiment; FIG. 4 is a flowchart of water sprinkling control performed by the water sprinkling apparatus according to the embodiment; FIG. 5 is another flowchart of water sprinkling control performed by the water sprinkling apparatus according to the embodiment; and FIG. 6 is a diagram for describing water sprinkling control according to a variation. Description of Embodiments[Embodiments]

[0010] Hereinafter, an embodiment of the present disclosure is described.<Configuration of Refrigerant Cooling Apparatus Including Water Sprinkling Apparatus>

[0011] First, a configuration of a refrigerant cooling apparatus including a water sprinkling apparatus according to an embodiment of the present disclosure is described. FIG. 1 is a front view of a refrigerant cooling apparatus. FIG. 2 is a side view of the refrigerant cooling apparatus. FIG. 3 is a block diagram illustrating a control system of a water sprinkling apparatus. Note that the number of constituent members of the refrigerant cooling apparatus is not limited to the number exemplified below.

[0012] Refrigerant cooling apparatus 1 illustrated in FIGS. 1 and 2 cools a refrigerant compressed by a compressor of a refrigeration apparatus (not illustrated). Refrigerant cooling apparatus 1 includes cooling unit 2 and auxiliary cooling apparatus 3.

[0013] Cooling unit 2 includes main body 21 and two heat exchangers 22.

[0014] Main body 21 houses two heat exchangers 22. Main body 21 is formed in a rectangular box shape. Opening 211 is formed on each of the side walls of main body 21 on the right side (right side wall) and the left side (left side wall) in FIG. 1. Through openings 211, air outside of main body 21 is introduced into main body 21.

[0015] Fan 23 is disposed on an upper wall of main body 21. Fan 23 is driven based on the control of a unit controller (not illustrated). Fan 23 discharges the air inside of main body 21 above main body 21.

[0016] Heat exchanger 22, which is a so-called air-cooled heat exchanger, exchanges heat between a refrigerant compressed by a compressor and the air around heat exchanger 22 and sends the cooled refrigerant after the heat exchange to an evaporator via an expansion valve of the refrigeration apparatus. The cooling target of the refrigeration apparatus is cooled by heat exchange between the refrigerant sent to the evaporator and the air around the evaporator. Two heat exchangers 22 are disposed so as to face respective openings 211 on the right and left side walls of main body 21. Two heat exchangers 22 are inclined so that the distance between the upper ends is longer than the distance between the lower ends when viewed from the front side (front side in FIG. 1) of main body 21. Note that two heat exchangers 22 may be disposed so that, when viewed from the front side of main body 21, the distance between the upper ends is the same as the distance between the lower ends, or the distance between the upper ends is shorter than the distance between the lower ends.

[0017] Auxiliary cooling apparatus 3 cools heat exchangers 22. Auxiliary cooling apparatus 3 includes two water sprinkled mats 31 and water sprinkling apparatus 4.

[0018] Two water sprinkled mats 31 are disposed outside main body 21 and at positions respectively facing the right side wall and the left side wall of main body 21. Water sprinkled mats 31 are formed of materials having air permeability and each have a plate shape. Water sprinkled mats 31 each include first main surface 31A and second main surface 31B located on a side opposite to first main surface 31A. Water sprinkled mats 31 are disposed so that first main surface 31A and second main surface 31B are substantially parallel to the vertical direction and cover openings 211 of main body 21. Each water sprinkled mat 31 is disposed so that first main surface 31A faces heat exchanger 22. On the side of second main surface 31B of each water sprinkled mat 31, a filter (not illustrated) is disposed. The filters prevent foreign substances from attaching to water sprinkled mat 31, thereby preventing air from passing through water sprinkled mat 31 with difficulty.

[0019] Water sprinkled mat 31 may be formed of a material that has low resistance during air passage and is capable of smoothly exchanging heat with water. As water sprinkled mat 31 that easily passes air, non-woven fibers can be exemplified. Water sprinkled mat 31 may be formed of a material having water absorbability and high durability. The thickness of water sprinkled mat 31 is approximately several centimeters, for example. From the viewpoint of effective utilization of resources, it is preferred to use water sprinkled mat 31 made from recycled waste plastic reprocessed into a fiber form. From the viewpoint of ease of installation of water sprinkled mat 31, it is preferred that water sprinkled mat 31 be formed of a stretchable material. Water sprinkled mat 31 may be configured as a single mat, or may be configured as a plurality of mats arranged in at least one of the up-down direction and the front-rear direction.

[0020] Water sprinkling apparatus 4 supplies water to water sprinkled mat 31 disposed at a position facing heat exchanger 22, removes heat of evaporation from the air passing through water sprinkled mat 31 wet with water, along with the evaporation of water, and exchanges heat between the air from which heat of evaporation has been removed (hereinafter, sometimes referred to as "cooling air") and heat exchanger 22, thereby cooling heat exchanger 22. When supplying water to water sprinkled mat 31, water sprinkling apparatus 4 detects the position of the lower end of the area in which water sprinkled mat 31 is wet (hereinafter, sometimes referred to as "wet area"), and adjusts the amount of water to be supplied to water sprinkled mat 31 based on the position of the lower end of the wet area. Water sprinkling apparatus 4 includes water supply unit 41 and six lower-end detectors 42.

[0021] Water supply unit 41 supplies water to water sprinkled mat 31 based on the control of controller 47 to be described later. Water supply unit 41 includes two water sprinkling headers 411, water supply pipe 412, water supply device 413, six flow control valves 414, and four water discharge pipes 415.

[0022] One of two water sprinkling headers 411 is disposed on the left side above water sprinkled mat 31, and the remaining water sprinkling header 411 is disposed on the right side above water sprinkled mat 31. Water sprinkling header 411 supplies water to water sprinkled mat 31 located below water sprinkling header 411. Water sprinkling header 411 is formed in a box shape extending from a front end (right end in FIG. 2) to a rear end (left end in FIG. 2) of water sprinkled mat 31. On the bottom wall of each water sprinkling header 411, a plurality of water sprinkling holes (not illustrated) arranged in the front-rear direction of water sprinkled mat 31 is formed. Inside water sprinkling header 411, partitions 411B that partition the internal space of water sprinkling header 411 into a plurality of divided spaces 411A (three divided spaces 411A in the present embodiment) are formed.

[0023] Water supply pipe 412 supplies water to water sprinkling header 411. Water supply pipe 412 includes base pipe portion 412A extending upward and downward on the rear side of main body 21. The lower end of base pipe portion 412A is connected to water supply device 413. Water supply device 413 is driven based on the control of controller 47. The upper end of base pipe portion 412A is connected to the center of intermediate pipe portion 412B extending rightward and leftward. To the left and right ends of intermediate pipe portion 412B, horizontal pipe portions 412C extending in the front-rear direction and above water sprinkled mats 31 disposed on the left and right sides are connected. To a plurality of portions (three portions in the present embodiment) of horizontal pipe portion 412C arranged in the front-rear direction, perpendicular pipe portions 412D extending upward and downward are connected. The lower end of each perpendicular pipe portion 412D is connected to a portion of the upper wall of water sprinkling header 411 corresponding to each divided space 411A. That is, water supply pipe 412 includes six perpendicular pipe portions 412D. Each of six perpendicular pipe portions 412D is provided with one flow control valve 414. Flow control valve 414 continuously or intermittently adjusts the flow rate of the water flowing from perpendicular pipe portion 412D to water sprinkling header 411 based on the control of controller 47.

[0024] With the above-described configuration, the water supplied from water supply device 413 passes through each perpendicular pipe portion 412D and each divided space 411A of water sprinkling header 411, and is supplied (dropped) to the area of water sprinkled mat 31 located vertically below each divided space 411A. Further, the amount of water flowing into each divided space 411A of water sprinkling header 411 is individually controlled by adjusting the opening degree of corresponding flow control valve 414. Portions of water sprinkling header 411 constituting one divided space 411A, one perpendicular pipe portion 412D that supplies water to the one divided space 411A, and one flow control valve 414 provided to the one perpendicular pipe portion 412D constitute one water supply section 40. Water supply section 40 mainly supplies water to divided area 311 located under divided space 411A among a plurality of divided areas 311 (three divided areas 311 in the present embodiment) obtained by dividing one water sprinkled mat 31 in the width direction. Note that, in FIG. 2, boundary lines of divided areas 311 are indicated by two-dot chain lines, but adjacent divided area 311 is possibly wetted by the water supplied from each water supply section 40 to the corresponding one of divided areas 311. Water supply unit 41 includes the same number of water supply sections 40 as the number of divided areas 311 (Six water supply sections 40 in total since two water sprinkled mats 31 are provided in the present embodiment).

[0025] Water discharge pipe 415 discharges, among the water supplied to water sprinkled mat 31, the water that has reached the lower end of water sprinkled mat 31 without evaporating, below water sprinkled mat 31. Water discharge pipes 415 are respectively disposed on the front side and the rear side and below water sprinkled mat 31. Note that a configuration may be provided in which the water discharged from water discharge pipe 415 is returned to water supply device 413, and the water returned to water supply device 413 may be reused as water to be supplied to water sprinkled mat 31. Further, the water discharged from water discharge pipe 415 may be discarded without being reused as water to be supplied to water sprinkled mat 31.

[0026] Each lower-end detector 42 detects the lower end position of wet area of corresponding divided area 311 in water sprinkled mat 31. Each lower-end detector 42 includes inner dry-bulb temperature detector 43 and wet-bulb temperature detector 44.

[0027] Each inner dry-bulb temperature detector 43 detects a dry-bulb temperature between divided area 311 and heat exchanger 22 (hereinafter, sometimes referred to as "inner dry-bulb temperature"). Each inner dry-bulb temperature detector 43 may be disposed in the vicinity of divided area 311. For example, although the distance from each inner dry-bulb temperature detector 43 to the corresponding one of divided areas 311 is not limited, each inner dry-bulb temperature detector 43 is disposed between divided area 311 and heat exchanger 22 and at a position where inner dry-bulb temperature detector 43 is not affected by water droplets of rainfall or sprinkling. Further, even though inner dry-bulb temperature detector 43 is configured as a detector not affected by water droplets of rainfall or sprinkling, the distance from each inner dry-bulb temperature detector 43 to the corresponding one of divided areas 311 is not limited. Each Inner dry-bulb temperature detector 43 may be disposed at a position that is between divided area 311 and heat exchanger 22 and satisfies the following Expression 1. Lm × 0.9 ≤ L 1 ≤ Lm × 0.75 Lm: Distance from the upper end to the lower end of divided area 311 (water sprinkled mat 31) L1: Distance from the upper end of divided area 311 (water sprinkled mat 31) to inner dry-bulb temperature detector 43.

[0028] Inner dry-bulb temperature detectors 43 each includes inner dry-bulb temperature sensor 431 that detects an inner dry-bulb temperature. Each inner dry-bulb temperature sensor 431 outputs a signal corresponding to the inner dry-bulb temperature to controller 47.

[0029] Each wet-bulb temperature detector 44 detects a wet-bulb temperature at a position opposite to heat exchanger 22 with respect to divided area 311 (hereinafter, sometimes referred to as "outer wet-bulb temperature"). Each wet-bulb temperature detector 44 may be disposed in the vicinity of divided area 311. For example, although the distance from each wet-bulb temperature detector 44 to the corresponding one of divided areas 311 is not limited, each wet-bulb temperature detector 44 is disposed in the vicinity of divided area 311 so as not to be affected by water droplets of rainfall or sprinkling. Further, even though each wet-bulb temperature detector 44 is configured as a detector not affected by water droplets of rainfall or sprinkling, each wet-bulb temperature detector 44 may be disposed at any position as long as each wet-bulb temperature detector is disposed in the vicinity of divided area 311, and the distance from each wet-bulb temperature detector 44 to divided area 311 is not limited. Each wet-bulb temperature detector 44 may be disposed at a position that is opposite to heat exchanger 22 with respect to divided area 311 and satisfies the following Expression 2. In the present embodiment, each wet-bulb temperature detector 44 is disposed so that distance L2 from the upper end of divided area 311 to wet-bulb temperature detector 44 is substantially the same as distance L1 from the upper end of divided area 311 and inner dry-bulb temperature detector 43. Note that, when it can be regarded that the wet-bulb temperature of divided area 311 on the upper end side and the wet-bulb temperature of divided area 311 on the lower end side are the same or substantially the same, each wet-bulb temperature detector 44 may be disposed above or below corresponding inner dry-bulb temperature detector 43. Lm × 0.9 ≤ L 2 ≤ Lm × 0.75 L2: Distance from the upper end of divided area 311 (water sprinkled mat 31) to wet-bulb temperature detector 44

[0030] Wet-bulb temperature detectors 44 each include outer dry-bulb temperature sensor 441 and humidity sensor 442.

[0031] Each outer dry-bulb temperature sensor 441 detects a dry-bulb temperature outside of corresponding divided area 311 (side opposite to heat exchanger 22 with respect to water sprinkled mat 31) (hereinafter, sometimes referred to as "outer dry-bulb temperature"). Each outer dry-bulb temperature sensor 441 may be disposed between humidity sensor 442 and divided area 311. For example, each outer dry-bulb temperature sensor 441 may be disposed at a position where the distance to humidity sensor 442 is equal to or less than 10 mm. Note that FIG. 1 illustrates an example in which each outer dry-bulb temperature sensor 441 is disposed between humidity sensor 442 and divided area 311, but each outer dry-bulb temperature sensor 441 may be disposed at any position as long as each outer dry-bulb temperature sensor 441 is disposed in the vicinity of humidity sensor 442. For example, each outer dry-bulb temperature sensor 441 may be disposed in front of or behind humidity sensor 442, or each outer dry-bulb temperature sensor 441 may be disposed on a side opposite to divided area 311 with respect to humidity sensor 442 as illustrated in FIG. 1. Each outer dry-bulb temperature sensor 441 outputs a signal corresponding to the outer dry-bulb temperature to controller 47.

[0032] Each humidity sensor 442 detects humidity outside of corresponding divided area 311 (hereinafter, sometimes referred to as "outer humidity"). Each humidity sensor 442 outputs a signal corresponding to the outer humidity to controller 47. Based on the outer dry-bulb temperature and the outer humidity, an outer wet-bulb temperature at a position opposite to heat exchanger 22 with respect to each divided area 311 is calculated.

[0033] The lower end of wet area of water sprinkled mat 31 is detected by lower-end detector 42 having the above-described configuration, based on the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature. A description is herein given of the reason why the lower end of wet area of water sprinkled mat 31 (divided area 311) can be detected based on the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature.

[0034] When water sprinkling control (to be described later) using water sprinkling apparatus 4 is performed, fan 23 is driven. Driving fan 23 causes an airflow from the outside of water sprinkled mat 31 toward the inside (between water sprinkled mat 31 and heat exchanger 22) as indicated by arrow A in FIG. 1. This air, which has passed through water sprinkled mat 31 (hereinafter, sometimes referred to as "passing air"), is guided by fan 23 in a direction approaching heat exchanger 22. Heat exchanger 22 is cooled by heat exchange with the passing air. The passing air with which heat exchanger 22 has heat-exchanged passes through heat exchangers 22, and is discharged above main body 21.

[0035] When water sprinkled mat 31 is wet, heat of evaporation is removed from the passing air along with evaporation of water from water sprinkled mat 31. Heat exchanger 22 is cooled by the passing air from which heat of evaporation is removed, that is, cooling air. Further, along with supply of water from above water sprinkled mat 31 to water sprinkled mat 31, heat of evaporation is removed along with evaporation of water from the passing air at a lower position as the wet area of water sprinkled mat 31 expands downward. Then, the inner dry-bulb temperature detected by inner dry-bulb temperature detector 43 decreases. As a result, unless the outer wet-bulb temperature greatly changes due to a sudden change in weather or the like, the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature decreases as the wet area of water sprinkled mat 31 expands downward, that is, as the lower end of the wet area moves downward. In the case that the lower end of the wet area is located above inner dry-bulb temperature detector 43, the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature decreases as the lower end of the wet area moves downward. However, in the case that the lower end of the wet area is located below inner dry-bulb temperature detector 43, the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature hardly changes even when the lower end of the wet area moves downward. In the present embodiment, as described above, the position of the lower end of the wet area is detected based on the relation in which the position of the lower end of wet area of water sprinkled mat 31 approaches inner dry-bulb temperature detector 43 as the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature decreases. Thus, the position of the lower end of the wet area can be easily detected by simple processing compared to the configuration in which the position of the lower end of the wet area is detected using image processing, for example.

[0036] As illustrated in FIG. 3, water sprinkling apparatus 4 further includes operation section 45, storage section 46, and controller 47.

[0037] Operation section 45 is configured to transmit and receive various signals to and from controller 47. Operation section 45 is operated by a user of auxiliary cooling apparatus 3. Operation section 45 outputs a signal corresponding to the operation to controller 47. For example, when receiving an operation indicating start of water sprinkling control, operation section 45 outputs a signal to start the water sprinkling control to controller 47. When receiving an operation indicating end of the water sprinkling control, operation section 45 outputs a signal to end the sprinkling control to controller 47.

[0038] Storage section 46 is configured to transmit and receive various data to and from controller 47. Storage section 46 stores various data for controlling water sprinkling apparatus 4. For example, storage section 46 stores information for calculation indicating the relation between the outer dry-bulb temperature, the outer humidity, and the outer wet-bulb temperature. Storage section 46 further stores a threshold value used for determining whether to perform water sprinkling control, and a target value used for adjusting the amount of water supplied to water sprinkled mat 31.

[0039] Controller 47 adjusts the amount of water to be supplied to water sprinkled mat 31 based on the position of the lower end of wet area of water sprinkled mat 31. Thus, the amount of water discharged below water sprinkled mat 31 without evaporating can be reduced. In the present embodiment, controller 47 adjusts, for each of a plurality of divided areas 311 of water sprinkled mat 31, the amount of water supplied by the corresponding one of water supply sections 40, based on the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature at a position corresponding to each divided area 311. In the case that water sprinkled mat 31 is large in size, the entire water sprinkled mat 31, that is, a plurality of divided areas 311 may not be evenly wetted due to a difference in suction speeds of air between portions of heat exchanger 22, unevenness of filter of water sprinkled mat 31, or the like. As in the present embodiment, having a configuration in which the amount of water supply is adjusted for each divided area 311 makes it possible to supply water to the corresponding one of divided areas 311 depending on the degree of wet even when water sprinkled mat 31 is large in size. Therefore, a plurality of divided areas 311 can be evenly wetted, and heat exchangers 22 can be evenly cooled.

[0040] Controller 47 is configured to transmit and receive various signals to and from water supply device 413, six flow control valves 414, six inner dry-bulb temperature detector 43, or six wet-bulb temperature detectors 44. Note that FIG. 3 illustrates one flow control valve 414, one inner dry-bulb temperature detector 43, and one wet-bulb temperature detector 44.<Operation of Water Sprinkling Apparatus>

[0041] Next, operation of water sprinkling apparatus 4 is described. FIGS. 4 and 5 are flowcharts of water sprinkling control performed by water sprinkling apparatus 4. Note that, in the following description, water sprinkling control for one divided area 311 among six divided areas 311 included in two water sprinkled mats 31 is described, but the same water sprinkling control as described below is also performed for the remaining five divided areas 311.

[0042] As illustrated in FIG. 4, controller 47 determines whether to start water sprinkling control based on a signal from operation section 45 (Step S1). When determining not to start water sprinkling control (Step S1: NO), controller 47 adjusts the opening degree of flow control valve 414 to be 0% (Step S2). By the process of Step S2, no water is supplied from water supply section 40 to divided area 311. After performing processing of Step S2, controller 47 performs processing of Step S1.

[0043] On the other hand, when determining to start water sprinkling control (Step S1: YES), controller 47 determines whether the outer humidity is less than a threshold value based on a signal from humidity sensor 442 (Step S3). The threshold value can be exemplified as 85%, which is the humidity level during rainfall. However, the threshold value may be other than 85% as long as the humidity value is the one indicating that it is raining. Note that the unit controller may start driving fan 23 when determining to start water sprinkling control in Step S1, or may keep fan 23 running continuously regardless of whether the unit controller determines to start the water sprinkling control.

[0044] When determining that the outer humidity is not less than the threshold value (Step S3: NO), controller 47 adjusts the opening degree of flow control valve 414 to be 0% (Step S2). The case that it is determined that the outer humidity is not less than the threshold value is the case that it is raining. When it is raining, divided areas 311 are wet with rain without supply of water from water supply section 40 to divided areas 311, and thus the water evaporates from divided area 311. Heat exchanger 22 is cooled by the cooling air generated by the evaporation of water. Note that, when the opening degree of flow control valve 414 has been adjusted to be 0% by the time when it is determined that the outer humidity is not less than the threshold value (Step S3: NO), controller 47 performs the processing of Step S1 without performing the processing of Step S2 and determines to start the water sprinkling control in the processing of Step S1.

[0045] On the other hand, when determining that the outer humidity is less than the threshold value (Step S3: YES), controller 47 calculates the outer wet-bulb temperature based on an outer dry-bulb temperature that is based on the signal from outer dry-bulb temperature sensor 441, an outer humidity that is based on the signal from humidity sensor 442, and information for calculation stored in storage section 46 (Step S4). The case that it is determined that the outer humidity is less than the threshold value is the case that it is not raining, for example, that it is fine weather. Next, controller 47 calculates a temperature difference between the outer wet-bulb temperature and an inner dry-bulb temperature that is based on a signal from inner dry-bulb temperature sensor 431 (Step S5). The inner dry-bulb temperature never falls below the outer wet-bulb temperature, and thus controller 47 calculates a value by subtracting the outer wet-bulb temperature from the inner dry-bulb temperature as a temperature difference.

[0046] Next, controller 47 determines whether the temperature difference is less than a target value+2K (Step S6). The target value of the temperature difference is preferably set to a temperature difference obtained when the position of the lower end of the wet area is at the same height as the inner dry-bulb temperature detector 43 or is slightly lower than inner dry-bulb temperature detector 43 (the distance from inner dry-bulb temperature detector 43 to the lower end of the wet area is not more than 10 mm). Setting the target value to such a value makes it possible to set the position of the lower end of the wet area at the time when controller 47 determines that the temperature difference is equal to or lower than the target value as described later, to a position substantially the same as that of inner dry-bulb temperature detector 43 or a position slightly lower than that of inner dry-bulb temperature detector 43. Thus, when controller 47 determines that the temperature difference is equal to or less than the target value, the amount of water discharged downward without evaporating from divided areas 311 can be 0 or a predetermined amount or less by reducing the supply of water and suppressing the downward movement of the position of lower end of the wet area. As the target value, for example, a value between 2K or more and 3K or less can be exemplified.

[0047] When determining that the temperature difference is not less than the target value+2K (Step S6: NO), controller 47 increases the opening degree of flow control valve 414 by a first adjustment amount, and supplies water to divided area 311 (Step S7). The first adjustment amount is an amount sufficiently greater than that of a second adjustment amount to be described later. As the first adjustment amount, a value between 70% or more and 100% or less can be exemplified. After Step S7 is processed and a predetermined period elapses, controller 47 performs the processing of Step S6.

[0048] When the opening degree of flow control valve 414 is increased by the process of Step S7, the amount of water supplied to divided area 311 per unit time increases. When the amount of water supplied per unit time is greater than the amount of water evaporating from divided area 311 per unit time, the lower end of the wet area moves downward, and the area in which water evaporates increases in divided area 311. When the area in which water evaporates increases, the area of heat exchanger 22 being into contact with the cooling air increases. Further, the cooling air is generated at a lower position, so that the inner dry-bulb temperature is lowered, and unless the outer wet-bulb temperature significantly changes due to a sudden change in weather or the like, the temperature difference reduces when the processing of Step S7 is performed.

[0049] On the other hand, when determining that the temperature difference is less than the target value+2K (Step S6: YES), controller 47 determines whether the temperature difference is less than the target value+1K as illustrated in FIG. 5 (Step S8). The case that it is determined that the temperature difference is less than the target value+2K is the case that divided area 311 is wet to some extent. When determining that the temperature difference is not less than the target value+1K (Step S8: NO), controller 47 increases the opening degree of flow control valve 414 by the second adjustment amount, and supplies water to divided area 311 (Step S9). The case that it is determined that the temperature difference is not less than the target value +1K is the case that part of divided area 311 is wet but the amount of water sprinkled is insufficient to set the temperature difference to the target value. The second adjustment amount is an amount greater than that of a third adjustment amount to be described later. As the second adjustment amount, a value between 50% or more and less than 70% can be exemplified. After Step S9 is processed and a predetermined period elapses, controller 47 performs the processing of Step S8.

[0050] When the processing of Step S9 is performed, the amount of water supplied to divided area 311 per unit time decreases and the speed at which the wet area of divided area 311 expands reduces, compared to the case that the opening degree of flow control valve 414 is further increased by the first adjustment amount. However, the supply of water to divided area 311 continues, so that the wet area continues to expand downward as long as the amount of water supplied per unit time continues to be greater than the amount of water evaporating from divided area 311 per unit time. As a result, the area of heat exchanger 22 being in contact with the cooling air further increases. Further, the cooling air is generated at a lower position. Thus, the inner dry-bulb temperature is lowered, and unless the outer wet-bulb temperature significantly changes due to a sudden change in weather or the like, the temperature difference decreases when the processing of Step S9 is performed. Further, when the processing of Step S9 is performed, the rate of decrease in the temperature difference per unit time decreases compared to the case that the opening degree of flow control valve 414 is further increased by the first adjustment amount. Thus, decrease in the temperature difference to significantly below the target value can be suppressed. As a result, it is possible to prevent the lower end of the wet area from being unintentionally and excessively moved downward and to prevent water contained in divided area 311 from being discharged downward without evaporating.

[0051] On the other hand, when determining that the temperature difference is less than the target value+1K (Step S8: YES), controller 47 increases the opening degree of flow control valve 414 by the third adjustment amount (Step S10). The case that it is determined that the temperature difference is less than the target value+1K is the case that the time difference approaches the target value. The third adjustment amount is substantially the same as a fourth adjustment amount to be described later. As the third adjustment amount, a value between 30% or more and less than 50% can be exemplified. When the processing of Step S10 is performed, the speed at which the wet area increases reduces compared to the case that the opening degree of flow control valve 414 is further increased by the first adjustment amount or the second adjustment amount. However, the wet area continues to expand downward as long as the amount of water suppled per unit time is greater than the amount of water evaporating from divided area 311 per unit time. As a result, the area of heat exchanger 22 being in contact with the cooling air further increases. Further, the cooling air is generated at a lower position, so that, unless the outer wet-bulb temperature significantly changes due to a sudden change in weather or the like, the temperature difference decreases when the processing of Step S10 is performed. Further, by the process of Step S10, the rate of decrease in the temperature difference per unit time decreases compared to the case that the opening degree of flow control valve 414 is further increased by the first adjustment amount or the second adjustment amount. Thus, decrease in the temperature difference significantly below the target value can be suppressed. As a result, it is possible to prevent the lower end of the wet area from unintentionally and excessively moving downward and to prevent water contained in divided area 311 from being discharged downward without evaporating.

[0052] Next, controller 47 determines whether the temperature difference is equal to or less than the target value (Step S11). When determining that the temperature difference is not equal to or less than the target value (Step S11: NO), controller 47 performs the processing of Step S10 after a predetermined period of time elapses. The case that it is determined that the temperature difference is not equal to or less than the target value is the case that the temperature difference and the target value are substantially the same. On the other hand, when determining that the temperature difference is equal to or less than the target value (Step S11: YES), controller 47 decreases the opening degree of flow control valve 414 by the fourth adjustment amount (Step S12). The case that it is determined that the temperature difference is equal to or less than the target values is the case that water is supplied to divided area 311 that is difficult to dry (where it is difficult for water to evaporate), resulting in lowering the position of lower end of the wet area to the vicinity of inner dry-bulb temperature detector 43, and the amount of water discharged below divided area 311 without evaporating (the amount of discharged water) possibly increases. The case that divided area 311 becomes difficult to dry (where it becomes difficult for water to evaporate) is, for example, the case that the outside humidity is high. As the fourth adjustment amount, a value between 0% or more and less than 30% can be exemplified. After Step S12 is processed and a predetermined period elapses, controller 47 performs the processing of Step S11. Note that, when acquiring a signal to end the water sprinkling control from operation section 45 during the above-described water sprinkling control, controller 47 ends the water sprinkling control.

[0053] As described above, in Step S11, controller 47 repeats the process of decreasing the opening degree of flow control valve 414 by the fourth adjustment amount (Step S12) until it is determined that the temperature difference is not equal to or less than the target value. When the amount of water supplied to divided area 311 per unit time is reduced by the process of Step S12, the speed at which the wet area increases reduces compared to the case that the amount of water supplied to divided area 311 is increased. As long as the wet area continues to expand downward, the area of heat exchanger 22 being in contact with the cooling air increases while the temperature difference decreases. However, when the amount of water supplied to divided area 311 per unit time continues to be reduced and the amount of water supply becomes less than the amount of water evaporating from divided area 311 per unit time, the wet area starts drying from the lower side of divided area 311, and the lower end of the wet area moves upward. When the lower end of the wet area moves upward, the area of heat exchanger 22 being in contact with the cooling air decreases while the inner dry-bulb temperature detected by inner dry-bulb temperature detector 43 increases, and then the temperature difference increases. Then, in Step S11, when determining that the temperature difference exceeds the target value, that is, the temperature difference is not equal to or less than the target value, controller 47 performs the processing of Step S10 and increases the amount of water supplied to divided area 311 per unit time. Such processing of Step S10 causes the lower end of the wet area to move downward, and the area of heat exchanger 22 being in contact with the cooling air increases while the temperature difference decreases. Then, controller 47 repeats the process of Step S10 until the temperature difference becomes equal to or less than the target value, and when the temperature difference becomes equal to or less than the target value, the process of Step S12 is repeated until the temperature difference exceeds the target value.

[0054] Water sprinkling apparatus 4 performs the above-described processes to adjust the amount of water supplied to divided area 311 so that the temperature difference reaches the target value, that is, the lower end of the wet area is located in the vicinity of inner dry-bulb temperature detector 43. Thus, the amount of water discharged downward without evaporating in divided area 311 can be reduced.

[0055] Water sprinkling apparatus 4 performs water sprinkling control based on the position of the lower end of the wet area when the outer humidity is less than a threshold value and it is estimated that it is not raining, but water sprinkling apparatus 4 does not performs the water sprinkling control when the outer humidity is equal to or more than the threshold value and it is estimated that it is raining. As described above, the water sprinkling control is performed in the situation where water sprinkled mat 31 is not wet, but, on the other hand, the water sprinkling control is not performed in the situation where water sprinkled mat 31 is wet with rain. This makes it possible to cool heat exchanger 22 while reducing the processing load of water sprinkling apparatus 4.

[0056] Inner dry-bulb temperature detector 43 is disposed at a position satisfying "L1 ≤ Lm × 0.75" in above Expression 1. Thus, by controller 47 adjusting the amount of water to be supplied, 75 % of the area on the upper side of divided area 311 can be always wet, which expands the area of heat exchanger 22 being in contact with the cooling air. Therefore, the cooling efficiency of heat exchanger 22 can be increased. Further, inner dry-bulb temperature detector 43 is disposed at a position satisfying "Lm × 0.9 ≤ L1" in above Expression 1. Thus, by controller 47 adjusting the amount of water to be supplied, the distance from the upper end of divided area 311 to the lower end of the wet area can be set to a distance of 90% or less of the height of divided area 311, which reduces the probability that water is discharged from divided area 311.

[0057] Further, in the case that a solenoid valve that allows only an alternative selection of opening or closing of a flow channel is provided to each water supply section 40 of water sprinkling apparatus 4, it is necessary to adjust the amount of water supply with a needle valve in consideration of the influence of water pressure at an initial stage of construction of water sprinkling apparatus 4, which possibility deteriorates the workability. Furthermore, when the water pressure changes, only an amount of water corresponding to the changed water pressure can be supplied, and thus each divided area 311 may not be properly wetted. Each water supply section 40 of the present embodiment includes flow control valve 414 capable of continuously or intermittently adjusting the flow rate of water. This eliminates the need of adjusting the amount of water supply at the initial stage of construction of water sprinkling apparatus 4. Further, when the water pressure changes, controller 47 adjusts the opening degree of flow control valve 414 depending on the change, so that divided areas 311 can be appropriately and evenly wetted.[Variations of Embodiment]

[0058] The present disclosure is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the present disclosure. Further, the embodiment described above and variations described below may be combined in any way as long as appropriate function can be obtained.

[0059] For example, a method for controlling the amount of water supplied to divided area 311 so that the temperature difference between the inner dry-bulb temperature and the outer wet-bulb temperature reaches the target value is not limited to the method illustrated in FIGS. 4 and 5, and a method illustrated in FIG. 6 may be applied. In the method illustrated in FIG. 6, when the water sprinkling control is started at time T0, the opening degree of flow control valve 414 is increased continuously until the temperature difference becomes equal to or less than the target value (2K) (until time T1). Then, when the temperature difference becomes equal to or less than the target value, the following two processes are repeated: the process of continuously decreasing the opening degree of flow control valve 414 until the temperature difference becomes equal to or higher than the target value + predetermined value (between time T1 and T2, time T3 and T4, time T5 and T6, and time T7 and T8); and the process of continuously increasing the opening degree of flow control valve 414 until the temperature difference becomes equal to or higher than the target value + predetermined value (between time T2 and T3, time T4 and T5, and time T6 and T7).

[0060] As lower-end detector 42, a configuration in which the position of the lower end of the wet area is detected by image-processing the image captured by an imaging unit may be applied. Further, a configuration in which the amount of water discharged from water discharge pipe 415 is detected (e.g., flow rate sensor) may be applied as lower-end detector 42, and controller 47 may perform the processes after Step S4 illustrated in FIG. 4 when the discharge of water from water discharge pipe 415 is detected, that is, when it is detected that the position of the lower end of the wet area has reached the lower end of water sprinkled mat 31, after controller 47 starts supplying water to water sprinkled mat 31.

[0061] As wet-bulb temperature detector 44, a wet-bulb temperature sensor that detects a wet-bulb temperature may be used instead of outer dry-bulb temperature sensor 441 and humidity sensor 442.

[0062] Regardless of the value of the outer humidity, that is, regardless of whether it is raining, water sprinkling apparatus 4 may perform water sprinkling control based on the position of the lower end of the wet area.

[0063] Although a configuration in which water supply section 40 and lower-end detector 42 are disposed at the corresponding positions in each divided area 311 has been exemplified, one water supply portion 40 and one lower-end detector 42 may be disposed in one water sprinkled mat 31.

[0064] Although a configuration in which flow control valve 414 capable of continuously or intermittently adjusting the flow rate of water is provided to each of water supply sections 40 has been exemplified, a solenoid valve that allows only an alternative selection of opening or closing the flow channel may be provided instead of flow control valve 414.Industrial Applicability

[0065] The present disclosure is applicable to a water sprinkling apparatus and a water sprinkling method.Reference Signs List

[0066] 1 Refrigerant cooling apparatus 2 Cooling unit 3 Auxiliary cooling apparatus 4 Water sprinkling apparatus 21 Main body 22 Heat Exchanger 23 Fan 31 Water sprinkled mat 31A First main surface 31B Second main surface 40 Water supply section 41 Water supply unit 42 Lower-end detector 43 Inner dry-bulb temperature detector 44 Wet-bulb temperature detector 45 Operation section 46 Storage section 47 Controller 211 Opening 311 Divided area 411 Water sprinkling header 411A Divided space 411B Partition 412 Water supply pipe 412A Base pipe portion 412B Intermediate pipe portion 412C Horizontal pipe portion 412D Perpendicular pipe portion 413 Water supply device 414 Flow control valve 415 Water discharge pipe 431 Inner dry-bulb temperature sensor 441 Outer dry-bulb temperature sensor 442 Humidity sensor

Claims

1. A water sprinkling apparatus (4) for cooling a heat exchanger (22) by air from which heat of evaporation is removed along with evaporation of water from a water sprinkled mat (31) wet with water, the water sprinkling apparatus (4) comprising: a lower-end detector (42) that detects a position of a lower end of a wet area of the water sprinkled mat (31); and a controller (47) that adjusts an amount of water supplied to the water sprinkled mat (31), based on the position of the lower end of the wet area, wherein the lower-end detector (42) includes: an inner dry-bulb temperature detector (43) disposed between the water sprinkled mat (31) and the heat exchanger (22) and detecting a dry-bulb temperature; and a wet-bulb temperature detector (44) disposed at a position opposite to the heat exchanger (22) with respect to the water sprinkled mat (31) and detecting a wet-bulb temperature, characterized in that the position of the lower end of the wet area is detected based on a temperature difference between the inner dry-bulb temperature and the wet-bulb temperature.

2. The water sprinkling apparatus (4) according to claim 1, wherein the position of the lower end of the wet area is detected based on a relation in which the position of the lower end of the wet area approaches the inner dry-bulb temperature detector (43) as the temperature difference between the dry-bulb temperature detected by the inner dry-bulb temperature detector (43) and the wet-bulb temperature detected by the wet-bulb temperature detector (44) decreases.

3. The water sprinkling apparatus (4) according to claim 2, wherein the wet-bulb temperature detector (44) includes a humidity sensor (442) that detects humidity and an outer dry-bulb temperature sensor (441) that detects a dry-bulb temperature, and the wet-bulb temperature is calculated based on the humidity detected by the humidity sensor (442) and the dry-bulb temperature detected by the outer dry-bulb temperature sensor (441).

4. The water sprinkling apparatus (4) according to claim 3, wherein the controller (47) adjusts the amount of water supplied to the water sprinkled mat (31) based on the position of the lower end of the wet area when the humidity detected by the humidity sensor (442) is less than a threshold value, and the controller does not supply water to the water sprinkled mat when the humidity detected by the humidity sensor (442) is equal to or more than the threshold value.

5. The water sprinkling apparatus (4) according to any one of claims 2 to 4, wherein the inner dry-bulb temperature detector (43) is disposed at a position satisfying a following Expression 1 between the water sprinkled mat (31) and the heat exchanger (22): Lm × 0.9 ≤ L 1 ≤ Lm × 0.75 Lm: Distance from an upper end to a lower end of the water sprinkled mat (31), and L1: Distance from the upper end of the water sprinkled mat (31) to the inner dry-bulb temperature detector (43).

6. The water sprinkling apparatus (4) according to any one of claims 2 to 5, further comprising a plurality of water supply sections (40) that respectively supply water to a plurality of divided areas (311) formed by dividing the water sprinkled mat (31) in a horizontal direction, wherein the inner dry-bulb temperature detector (43) and the wet-bulb temperature detector (44) are disposed at corresponding positions in each of the plurality of divided areas (311), and the controller (47) adjusts, for each of the plurality of divided areas (311), an amount of water supplied by a corresponding one of the plurality of water supply sections (40), based on the position of the lower end of the wet area.

7. The water sprinkling apparatus (4) according to claim 6, wherein each of the plurality of water supply sections (40) includes a flow control valve (414) for adjusting a flow rate of water, and the controller (47) adjusts, for each of the plurality of divided areas (311), the amount of water supplied by the corresponding one of the plurality of water supply sections (40) by controlling the flow control valve (414).

8. A water sprinkling method performed by a water sprinkling apparatus (4) for cooling a heat exchanger (22) by air from which heat of evaporation is removed along with evaporation of water from a water sprinkled mat (31) wet with water, the water sprinkling method comprising: detecting, by the water sprinkling apparatus (4), a position of a lower end of a wet area of the water sprinkled mat (31); and adjusting, by the water sprinkling apparatus (4), an amount of water supplied to the water sprinkled mat (31), based on the position of the lower end of the wet area, wherein the detecting includes: detecting, by an inner dry-bulb temperature detector (43) disposed between the water sprinkled mat (31) and the heat exchanger (22), a dry-bulb temperature; detecting, by a wet-bulb temperature detector (44) disposed at a position opposite to the heat exchanger (22) with respect to the water sprinkled mat (31), a wet-bulb temperature; and charaterized by detecting the position of the lower end of the wet area based on a temperature difference between the inner dry-bulb temperature and the wet-bulb temperature.

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