JP2016015398A - Method for detecting coolant leakage of cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting coolant leakage of a cooling system, enabling the coolant leakage to be determined before the cooling capacity of the cooling system is reduced even when a coolant pump is used for thermal energy transport by means of a coolant.SOLUTION: There is provided the method for detecting coolant leakage of a cooling system that includes: cooling apparatus 20a, 20b having evaporators 21a, 21b, coolant flow rate control valves 25a, 25b, and blowers 22a, 22b, respectively; a condenser 10; a coolant pump 11; a liquid tank 12; bypass piping 32; a bypass flow rate control valve 14 provided in the bypass piping 32; a liquid level sensor 13 for measuring a liquid level in the liquid tank 12; and a control unit C. In the method for detecting coolant leakage of the cooling system, the control unit C determines that the coolant leaks when a rate of a period of time in which the liquid level is equal to or higher than a predetermined level during operation is lower than a rate of a period of time in which the liquid level when there is no leakage of the coolant is equal to or higher than the predetermined level during operation.

Description

  The present invention relates to a refrigerant leakage detection method for a cooling system.

  In recent years, the amount of information processing has increased with the improvement of information processing technology and the development of the Internet environment. For this reason, a data processing center for processing a large amount of various types of information has attracted attention as a business. For example, in a server room of this data processing center, a large number of electronic devices such as computers and servers are installed in an integrated state, and are continuously operated day and night.

  In general, the rack mount method is the mainstream for installing electronic devices in a server room. The rack mount system is a system in which racks (casings) for storing electronic devices divided into functional units are stacked in a cabinet, and a large number of such cabinets are arranged on the floor of a server room.

Electronic devices that process these information have rapidly improved in processing speed and processing capacity, and the amount of heat generated from the electronic devices is steadily increasing. These electronic devices require a certain temperature environment for operation, and the temperature environment for normal operation is set to be relatively low. Therefore, if the electronic device is placed in a high temperature state, troubles such as system shutdown may occur. cause.
For this reason, the actual situation is that air conditioning power (air conditioner load) for operating air conditioners to cool the server room has increased significantly, not only in terms of cost reduction in corporate management, but also in the global environment. From the viewpoint of maintenance, it is an urgent task to reduce air conditioning power.

  On the other hand, if water leakage occurs in the server room, the electronic device may be damaged. Therefore, it is common to use latent heat transport of a refrigerant having a larger heat transport amount than water for cooling the electronic device. It is. Furthermore, in order to reduce the transport of refrigerant, a system that transports refrigerant using a gas-liquid density difference without using a compressor or a cooling system that uses a refrigerant pump that can transport refrigerant with less power than the compressor should be adopted. Can do.

However, when a refrigerant is used for heat transfer, the refrigerant is gasified under atmospheric pressure, so if a small amount of leakage occurs, the refrigerant will not be noticed and the amount of refrigerant in the system will decrease. However, there is a risk that the cooling capacity will decrease.
From such a background, as seen in Patent Document 1 and Patent Document 2, a refrigerant leakage detection technique for a cooling system using a refrigerant for heat transfer has been proposed.

  Patent Document 1 discloses a method for determining whether or not refrigerant leakage has occurred by measuring the amount of exergy loss in equipment constituting a refrigeration cycle, calculating a leakage index value that changes according to the amount of refrigerant that has leaked, and the like. Has been proposed.

  Patent Document 2 proposes that the refrigerant density is calculated from the differential pressure at the inlet / outlet of the decompression device and the refrigerant circulation amount, and compared with the refrigerant density measurement value to determine the refrigerant amount decrease.

JP 2012-47447 A JP 2011-106714 A

However, the refrigerant leakage detection method as described above is intended for a refrigeration cycle including a compressor and a decompression device, and makes a determination based on the degree of superheat and the degree of supercooling of the compressor.
In a cooling system that does not use a compressor, the amount of change due to a decrease in refrigerant is small, and refrigerant leakage may not be determined. Furthermore, when these measured values change to such an extent that refrigerant leakage can be determined, there is a risk that the cooling capacity will decrease and the temperature of the electronic device will increase.

  The present invention has been made in view of such circumstances, and even when a refrigerant pump is used for heat transfer by refrigerant, a refrigerant leakage detection method for a cooling system capable of determining refrigerant leakage before the cooling capacity is reduced. The purpose is to provide.

  In order to achieve the above object, a refrigerant leakage detection method for a cooling system according to the present invention is supplied to an evaporator that vaporizes refrigerant by heat exchange for cooling high-temperature exhaust gas discharged from an electronic device, and the evaporator. One or a plurality of cooling devices having a refrigerant flow control valve for adjusting the flow rate of the refrigerant liquid, a blower for supplying the high-temperature exhaust to the evaporator, and the refrigerant gas vaporized by the evaporator is liquefied. A condenser, a refrigerant pump that sends the refrigerant liquid liquefied by the condenser to the evaporator, a liquid tank that is installed on the suction side of the refrigerant pump and temporarily stores the refrigerant liquid, and a refrigerant that is sent by the refrigerant pump Among them, a bypass pipe for returning the excess refrigerant adjusted by the refrigerant flow control valve to the condenser, and an amount of the refrigerant provided on the bypass pipe and returned to the condenser are adjusted. In the refrigerant leakage detection method for a cooling system, comprising: an bypass flow control valve; a liquid level sensor for measuring a liquid level height of the refrigerant liquid in the liquid storage tank; The ratio of the time during which the engine is operated at a predetermined height or more is calculated, and the calculated time ratio is determined so that the liquid level when the refrigerant does not leak is operated at a predetermined height or more. It is determined that the refrigerant is leaking when it is lower than the proportion of the time during which it is present.

  According to the cooling system of the present invention, it is possible to realize a refrigerant leakage detection method for a cooling system that can determine refrigerant leakage before the cooling capacity is lowered even when a refrigerant pump is used for heat transfer by the refrigerant.

The figure which shows the cooling system which concerns on Embodiment 1 of this invention. The figure which shows the liquid level of the refrigerant | coolant in a liquid tank with respect to the opening degree of a bypass flow control valve. The figure which shows the ratio (frequency) which the liquid level of the refrigerant | coolant in the liquid tank in a certain time with respect to the opening degree of a bypass flow control valve operates at a predetermined value or more. The figure which shows the flowchart of control of a refrigerant | coolant leak detection method. The figure which shows the relationship between the load factor (%) in a cooling device, and the liquid level of the refrigerant | coolant in a liquid tank. The figure which shows the ratio (frequency) which the liquid level of the refrigerant | coolant in the liquid tank in a certain time and a load factor (%) operate | move with more than predetermined value. The figure which shows the cooling system which concerns on Embodiment 2 of this invention. The figure which shows the cooling system which concerns on the modification of Embodiment 2 of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
The present invention relates to a refrigerant leakage detection method of a cooling system using a refrigerant for heat conveyance, and more particularly, heat conveyance by a refrigerant pump without using a compressor to efficiently cool high-temperature exhaust heat from electronic equipment. This is a refrigerant leakage detection method.

<< Embodiment 1 >>
FIG. 1 shows a cooling system according to Embodiment 1 of the present invention.
The cooling system S1 according to the first embodiment is a system that cools an electronic device (not shown) such as a server to be cooled placed in the cooling target chamber 80 to a desired temperature.

The cooling system S1 is characterized in that it detects leakage of a refrigerant used for cooling an electronic device to be cooled.
The cooling system S1 is provided with a control device C, and the control device C controls equipment of the cooling system S1 described below. The control device C is, for example, a PLC (programmable logic controller) having a computer and peripheral circuits.

<Cooling devices 20a and 20b>
In the cooling target chamber 80, an electronic device (not shown) such as a server to be cooled is placed. Since the electronic equipment is continuously operated, high-temperature exhaust (high-temperature exhaust 23a, 23b) is exhausted from the electronic equipment.
In the cooling system S1, cooling devices 20a and 20b for cooling the high-temperature exhausts 23a and 23b from the electronic devices to be cooled in the cooling target chamber 80 are installed.

  In the cooling device 20a, an evaporator 21a that performs heat exchange between the refrigerant and the high-temperature exhaust 23a, a blower 22a that supplies the high-temperature exhaust 23a to the evaporator 21a, and a flow rate of the refrigerant that is supplied into the evaporator 21a are adjusted. A refrigerant flow control valve 25a is incorporated. The high-temperature exhaust 23a is cooled by the evaporation latent heat accompanying the evaporation of the refrigerant in the evaporator 21a.

  Similarly, the cooling device 20b includes an evaporator 21b that exchanges heat between the refrigerant and the high-temperature exhaust 23b, a blower 22b that supplies the high-temperature exhaust 23b to the evaporator 21b, and a flow rate of the refrigerant that is supplied into the evaporator 21b. A refrigerant flow control valve 25b for adjusting the flow rate is incorporated. The high-temperature exhaust 23b is cooled by the evaporation latent heat accompanying the evaporation of the refrigerant in the evaporator 21b.

  The refrigerant flow control valves 25a and 25b are automatically controlled in opening degree corresponding to the set temperature for cooling. That is, when the cooling load is large, the opening degree is large, and when the cooling load is small, the opening degree is controlled small.

<Condenser 10>
The cooling system S1 includes a cold heat source 40 that produces cold water, a cold water pump 41 that sends the cold water, and a condenser 10 in order to cool and liquefy the gasified refrigerant. The heat medium water is circulated between the cold heat source 40, the cold water pump 41, and the condenser 10 via the cold water pipe 42.
In the condenser 10, the refrigerant gasified by the evaporators 21a and 21b exchanges heat with cold water, and is cooled to a liquefaction temperature or lower to be liquefied. Of course, the condenser 10 may adopt other configurations.

<Refrigerant pump 11>
The liquefied refrigerant is stored in the liquid tank 12, which is a buffer tank, and then supplied to the refrigerant pump 11 and sent to the evaporators 21a and 21b. A pressure gauge (not shown) is provided upstream and downstream of the refrigerant pump 11, and the differential pressure upstream and downstream of the refrigerant pump 11 is measured and controlled so that the differential pressure becomes constant.

Thereby, a fixed amount of refrigerant is sent out from the refrigerant pump 11 toward the evaporators 21a and 21b.
The liquid tank 12 is provided with a liquid level sensor 13 that measures whether or not the liquid level of the refrigerant is equal to or higher than a predetermined height (predetermined value).

<Bypass piping 32 and bypass flow control valve 14>
The refrigerant pipe 31 is provided with a bypass pipe 32 and a bypass flow rate control valve 14 to prevent a closing operation in which the discharge side of the refrigerant pump 11 is closed. The opening degree of the bypass flow rate control valve 14 is controlled so that the differential pressure between the upstream and downstream sides of the refrigerant pump 11 is constant, in other words, the discharge flow rate of the refrigerant pump 11 is constant.

  That is, when the cooling load is large, the opening degree of the refrigerant flow control valves 25a and 25b is increased, and the amount of refrigerant sent to the cooling devices 20a and 20b is increased. Therefore, the amount of the refrigerant flowing through the bypass pipe 32 is reduced, and the opening degree of the bypass flow control valve 14 is controlled to be small. On the other hand, when the cooling load is small, the opening degree of the refrigerant flow rate control valves 25a and 25b becomes small, and the refrigerant delivery amount to the cooling devices 20a and 20b decreases. Therefore, the amount of refrigerant flowing through the bypass pipe 32 increases, and the opening degree of the bypass flow control valve 14 is largely controlled.

  As a measuring instrument for the opening degree of the bypass flow rate control valve 14, a relationship between the control current for opening and closing the bypass flow rate control valve 14 and the opening degree is obtained in advance, and the opening degree of the bypass flow rate control valve 14 is determined from the control current. You may ask for it. Alternatively, a flow meter may be provided before and after the bypass flow control valve 14, and the opening degree of the bypass flow control valve 14 may be obtained from the relationship between the flow rates measured by the front and rear flow meters. In addition, the measuring device of the opening degree of the bypass flow control valve 14 can be arbitrarily selected.

<Liquid surface level (liquid level height) of the refrigerant in the liquid tank 12>
Here, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 depends on the amount of refrigerant circulating in the system, and the ratio of the time of operation at a predetermined level or higher is the cooling device 20a, 20b. It is uniquely determined by the amount of cooling heat.

  That is, when the cooling heat load of the cooling devices 20a and 20b is large, the refrigerant is evaporated almost completely in the evaporators 21a and 21b, and therefore the refrigerant gas pipe 30 after passing through the evaporators 21a and 21b. Gas refrigerant flows through. Therefore, the refrigerant circulation amount is reduced and the liquid level of the refrigerant in the liquid tank 12 is high.

  On the other hand, when the loads on the cooling devices 20a and 20b are small, evaporation in the refrigerant evaporators 21a and 21b becomes incomplete, so that a gas-liquid refrigerant flows in the refrigerant gas pipe 30. That is, the refrigerant gas pipe 30 has more liquid refrigerant. Therefore, the refrigerant circulation amount increases and the liquid level of the refrigerant in the liquid tank 12 is low.

  On the other hand, when refrigerant leakage occurs from a pipe joint or the like, the refrigerant circulation amount in the system decreases, and the liquid level in the liquid tank 12 decreases because the refrigerant pump 11 sends out a predetermined amount of refrigerant. For this reason, the proportion of time during which the refrigerant in the liquid tank 12 is operated above the liquid level at the predetermined level (above the liquid level) is reduced.

  When the amount of cooling heat changes, the opening degree of the bypass flow rate control valve 14 changes, and the opening degree of the bypass flow rate control valve 14 is uniquely determined by the amount of cooling heat. As described above, when the amount of heat of cooling is large, the amount of refrigerant flowing through the bypass pipe 32 is increased, and the opening degree of the bypass flow rate control valve 14 is largely controlled. On the other hand, when the amount of heat of cooling is small, the amount of refrigerant flowing through the bypass pipe 32 is reduced, and the opening degree of the bypass flow rate control valve 14 is controlled to be small. That is, the amount of cooling heat (cooling load) of the cooling devices 20 a and 20 b is collected in the opening degree of the bypass flow rate control valve 14.

  From the above, the opening degree of the bypass flow rate control valve 14, that is, the cooling load amount of the cooling devices 20 a and 20 b and the liquid level (liquid level height) of the refrigerant in the liquid tank 12 are measured by the liquid level sensor 13. The ratio of driving at a predetermined value or more is measured. And the liquid level (liquid level height) of the refrigerant | coolant in the liquid tank 12 for every load amount in this ratio and normal driving | operation (when there is no leakage of a refrigerant | coolant) is more than the predetermined value measured with the liquid level sensor 13. It is possible to detect refrigerant leakage before the cooling capacity of the cooling devices 20a and 20b is reduced by comparing with the ratio of operation.

  For example, when refrigerant leakage occurs, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 for each cooling load amount at normal time (when there is no refrigerant leakage) is measured by the liquid level sensor 13. The ratio of operating at a liquid level (liquid level height) equal to or higher than a predetermined value measured by the liquid level sensor 13 is lower than the ratio of operating at a predetermined value or higher.

<Relationship Between Opening of Bypass Flow Control Valve 14 and Liquid Level of Refrigerant in Liquid Tank 12>
Next, the relationship between the opening degree of the bypass flow rate control valve 14 and the ratio at which the liquid level of the refrigerant in the liquid tank 12 operates at a predetermined value or higher will be described.
FIG. 2 shows the liquid level (liquid level height) of the refrigerant in the liquid tank with respect to the opening degree of the bypass flow control valve. The horizontal axis of FIG. 2 shows the opening degree (%) of the bypass flow rate control valve 14, and the vertical axis of FIG. 2 shows the liquid level (liquid level height) of the refrigerant in the liquid tank.

  FIG. 3 shows the ratio (frequency) at which the liquid level (liquid level height) of the refrigerant in the liquid tank within a certain period of time with respect to the degree of opening of the bypass flow control valve operates at a predetermined value or more. The horizontal axis of FIG. 3 shows the opening degree (%) of the bypass flow rate control valve 14, and the liquid level (liquid level height) of the refrigerant in the liquid tank within the time shown on the vertical axis of FIG. Indicates the frequency (ratio) (%) of driving.

As described above, the opening degree of the bypass flow rate control valve 14 is expressed by collecting the cooling loads of the cooling devices 20a and 20b.
An increase in the opening degree (%) of the bypass flow control valve 14 means that the opening degree of the refrigerant flow control valves 25a and 25b is small and the refrigerant return amount (bypass amount) through the refrigerant bypass pipe 32 is large. Is not used in cooling by the cooling devices 20a and 20b, which means that the cooling load is small.

  On the other hand, when the opening degree (%) of the bypass flow rate control valve 14 is small, the opening degree of the refrigerant flow rate control valves 25a and 25b is large and the return amount (bypass amount) of the refrigerant through the bypass pipe 32 is small. Therefore, the refrigerant is often used for cooling in the cooling devices 20a and 20b, and the cooling load is large.

  Therefore, when the opening degree (%) of the bypass flow rate control valve 14 is small, the return amount (bypass amount) of the refrigerant through the cooling bypass pipe 32 is small, so that the cooling load in the cooling devices 20a and 20b is large. Therefore, the rate at which the refrigerant evaporates is high in the cooling devices 20a and 20b, the refrigerant in the refrigerant gas pipe 30 is almost gasified, and the amount of refrigerant in the refrigerant gas pipe 30 is small. Therefore, the liquid level of the refrigerant in the liquid tank 12 is relatively high (see FIG. 2).

  On the other hand, when the opening degree (%) of the bypass flow control valve 14 is large, the refrigerant return amount (bypass amount) through the cooling bypass pipe 32 is large. Therefore, the heat load of cooling in the cooling devices 20a and 20b is small, the rate at which the refrigerant evaporates is low in the cooling devices 20a and 20b, the refrigerant in the refrigerant gas pipe 30 is in a gas-liquid mixed state, and the refrigerant gas pipe 30 The amount of refrigerant inside increases.

  Therefore, the liquid level of the refrigerant in the liquid tank 12 becomes relatively low (see FIG. 2). When the refrigerant is leaking, the amount of the refrigerant decreases, so the liquid level of the refrigerant in the liquid tank 12 is lower than the threshold level at normal operation (when there is no refrigerant leak). It will be. The threshold value is a liquid level that determines whether or not there is a refrigerant leak.

  Therefore, as shown in FIG. 3, during normal operation, the liquid level of the refrigerant in the liquid tank 12 is measured by the liquid level sensor 13 as the opening degree (%) of the bypass flow control valve 14 increases. The threshold of the ratio (frequency) (%) of driving tends to decrease in a quadratic function. This threshold means a ratio (frequency) (%) of operation at a predetermined value or more measured by the liquid level sensor 13 for determining whether or not there is a refrigerant leak.

  When the refrigerant leaks from the pipe line, the amount of the refrigerant decreases, so that the liquid level of the refrigerant in the liquid tank 12 is operated at a predetermined value or higher measured by the liquid level sensor 13 ( (Frequency) (%) is lower than a threshold value for determining whether or not in normal operation (when there is no refrigerant leakage). The actual liquid level of the refrigerant in the liquid tank 12 pulsates as the refrigerant increases or decreases. However, in FIGS. 2 and 3, the liquid level is represented by a solid line that takes approximately the intermediate value of the pulsation at the liquid level. Yes.

<Control of refrigerant leakage detection method>
Next, the flow of control of the refrigerant leakage detection method using the relationship shown in FIG. 3 will be described with reference to FIG.
FIG. 4 shows a flowchart of control of the refrigerant leakage detection method.

First, a planned amount of refrigerant is charged into the pipeline (the refrigerant gas pipe 30, the refrigerant liquid pipe 31, the bypass pipe 32, etc.) of the cooling system S1 (S101 in FIG. 4).
The planned amount of refrigerant is an amount that slightly exceeds the amount of liquid used to circulate the refrigerant through the pipeline (the refrigerant gas pipe 30, the refrigerant liquid pipe 31, the bypass pipe 32, etc.) of the cooling system S1. In other words, a refrigerant is put into a pipeline (refrigerant gas pipe 30, refrigerant liquid pipe 31, bypass pipe 32, etc.), and a safety factor is taken for the liquid level (liquid level height) of the refrigerant in the liquid tank 12. The amount is such that the refrigerant pump 11 can be reliably restarted.

  Subsequently, before normal operation of the cooling system S1, a heat load (cooling heat amount) that is considered to be generated in the cooling devices 20a and 20b is given in advance, and the cooling device 20a during normal operation (when there is no refrigerant leakage), The liquid level (liquid level height) of the refrigerant in the liquid level tank 12 is measured for each cooling heat quantity (every heat load) 20b. In this case, the sensor for measuring the liquid level is different from the liquid level sensor 13 and can measure the continuous liquid level with a linear liquid level sensor.

  In addition, during normal operation (when there is no refrigerant leakage), the ratio (frequency (%)) of time during which the liquid level (liquid level height) of the refrigerant in the liquid level tank 12 is operated at a predetermined value or more is obtained. Then, the opening degree of the bypass flow rate control valve 14 is measured. As described above, the opening degree of the bypass flow rate control valve 14 corresponds to the cooling heat amount of the cooling devices 20a and 20b, that is, the heat load.

  The ratio (frequency (%)) of this time is, for example, how long during the time period of 30 minutes to 50 minutes, etc., and the time during which the liquid level sensor 13 is ON (the liquid level is higher than a predetermined height). Means. Each opening of the bypass flow rate control valve 14 (cooling heat quantity of the cooling devices 20a and 20b) for judging whether or not normal operation (no refrigerant leakage) from the measured value of the ratio of time when it is ON (predetermined height or more) The threshold of the time ratio is set (S102). Here, the threshold value may be set with a measurement value or with a margin in the measurement value. If the measurement value of the time ratio is set with a margin, it can be set as a threshold that can be detected only when the refrigerant leaks more accurately.

Subsequently, normal operation (actual operation) of the cooling system S1 is performed (S103).
Then, the opening degree of the bypass flow rate control valve 14 is measured, and the liquid level (liquid level height) of the refrigerant in the liquid level tank 12 is measured by the liquid level sensor 13, so that the liquid level during the cooling operation of the electronic device is measured. The ratio of the time during which the liquid level in the surface tank 12 operates at a predetermined value or higher measured by the liquid level sensor 13 is measured (S104).

  Subsequently, the coolant level (liquid level height) in the liquid level tank 12 with respect to the opening degree of the bypass flow rate control valve 14 determined in S102 (cooling heat amount of the cooling devices 20a and 20b) is operated at a predetermined value or more. The threshold value of the time ratio and the liquid level (liquid level height) of the refrigerant in the liquid level tank 12 with respect to the opening of the bypass flow control valve 14 (cooling heat amount of the cooling devices 20a and 20b) measured in S104 are predetermined values. The ratio of the driving time is compared with the above (S105).

  And the ratio of the time which the liquid level (liquid level height) of the refrigerant | coolant in the liquid level tank 12 with respect to the opening degree of the bypass flow control valve 14 (cooling calorie | heat amount of cooling device 20a, 20b) is more than a predetermined value, It is determined whether or not the liquid level (liquid level height) of the refrigerant in the liquid level tank 12 of the threshold value is smaller than the ratio of the operating time at a predetermined value or more (S106).

If it is determined in S106 that the value is smaller than the threshold value (Yes in S105), it is determined that the refrigerant is leaking (S106).
On the other hand, if it is determined in S106 that the threshold is equal to or greater than the threshold (No in S105), it is determined that the refrigerant is not leaking (S108), and the process proceeds to S103.

<Relationship between load factor (%) in cooling devices 20a and 20b and liquid level>
Next, the relationship between the load factor (%) and the liquid level (liquid level height) in the cooling devices 20a and 20b will be described.
FIG. 5 shows the relationship between the load factor (%) in the cooling device and the liquid level of the refrigerant in the liquid tank. The horizontal axis of FIG. 5 shows the load factor (%) in the cooling devices 20a and 20b, and the vertical axis of FIG. 5 shows the liquid level of the refrigerant in the liquid tank 12.

  As shown in FIG. 5, when the cooling load (load factor (%)) of the cooling devices 20a and 20b is large, the refrigerant gas pipes 30 are almost completely evaporated in the refrigerant evaporators 21a and 21b. A gas refrigerant flows inside. Therefore, the refrigerant circulation amount is reduced and the liquid level of the refrigerant in the liquid tank 12 is high.

  On the other hand, when the cooling load (load factor (%)) of the cooling devices 20a and 20b is small, the refrigerant in the refrigerant gas pipe 30 is incompletely evaporated in the refrigerant evaporators 21a and 21b. Gas-liquid mixed refrigerant flows. For this reason, the amount of refrigerant in the refrigerant gas pipe 30 (see FIG. 1) in the pipe line increases, and the liquid level of the refrigerant in the liquid tank 12 becomes relatively low.

Therefore, the threshold that is the liquid level of the refrigerant in the liquid tank 12 during normal operation (when there is no refrigerant leakage) indicated by a broken line in FIG. 5 increases in a quadratic function.
On the other hand, when the refrigerant leaks, the amount of the refrigerant decreases, so that the liquid level of the refrigerant in the liquid tank 12 becomes lower than the threshold, as shown by the solid line in FIG.

  The actual liquid level of the refrigerant in the liquid tank 12 pulsates due to the increase or decrease of the refrigerant. However, when the refrigerant decreases (the solid line in FIG. 5), the liquid level It is expressed as an approximately intermediate value of the level pulsation.

  FIG. 6 shows the load ratio (%) and the ratio (frequency) at which the liquid level (liquid level height) of the refrigerant in the liquid tank within a certain time is operated at a predetermined value or more. The horizontal axis of FIG. 6 shows the load factor (%) in the cooling devices 20a and 20b, and the frequency (ratio) at which the liquid level of the refrigerant in the liquid tank in the time shown in the vertical axis of FIG. ) (%).

  From the relationship in FIG. 5, the frequency (%) at which the liquid level (liquid level height) of the refrigerant in the liquid tank 12 with respect to the load factor (%) is greater than or equal to a predetermined value measured by the liquid level sensor 13 is It is expressed as shown in FIG.

  That is, the frequency (%) at which the coolant level in the liquid tank 12 is operated at a predetermined value or higher with respect to the load factor (%) during normal operation (when there is no refrigerant leakage) has a high load factor (%). In some cases, it is relatively large, and when the load factor (%) is high, it is relatively small.

  Therefore, as shown by a broken line in FIG. 6, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 with respect to the load factor (%) during normal operation (when there is no refrigerant leakage) is a predetermined value or more. The threshold value of the operation frequency (%), that is, the threshold value for determining whether or not there is a refrigerant leak increases in a quadratic function.

  On the other hand, when there is refrigerant leakage, the amount of refrigerant decreases, so as shown by the solid line in FIG. 6, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 from the threshold value (dashed line in FIG. 6). The frequency (%) of driving at a predetermined value or more is low.

  From the above, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 with respect to the load factor (%) at the time of normal operation (when there is no refrigerant leakage) is greater than or equal to a predetermined value. A threshold value for determining whether or not there is a refrigerant leak may be set based on the frequency (%) of the operation at, and the refrigerant leak may be detected. In setting the threshold value, it is preferable to provide a margin (allowable range) so that refrigerant leakage can be accurately determined.

According to the above configuration, the liquid level sensor 13 that measures whether or not the liquid level of the refrigerant installed in the liquid tank 12 is equal to or higher than a predetermined level (height) is used during normal operation (the refrigerant leaks). Since the refrigerant leakage can be determined based on the frequency (%) (threshold value) of whether or not the liquid level of the refrigerant in the liquid tank 12 is higher than a predetermined level (height) in the case of no Can detect refrigerant leakage.
Further, if determination is made for each opening degree of the bypass flow control valve 14 or each cooling load, leakage of the refrigerant can be detected even when the cooling load changes.
Therefore, even when the refrigerant pump 11 is used for heat transfer by the refrigerant, it is possible to determine the leakage of the refrigerant before the cooling capacity is lowered.

  From the above, when refrigerant leakage occurs in the cooling system S1 that conveys the refrigerant by the refrigerant pump 11 without using the compressor, the refrigerant leakage is detected before the cooling capacity of the cooling devices 20a and 20b is reduced. This makes it possible to provide highly reliable air conditioning equipment.

<< Embodiment 2 >>
FIG. 7 shows a cooling system according to Embodiment 2 of the present invention.
The cooling system S2 of the second embodiment is the cooling system S1 of the first embodiment, in which one or a plurality of cooling devices 20a and 20ab are provided with a cooling heat quantity measuring unit that measures the cooling heat quantity for cooling the electronic device. It is.

In the cooling system S2 of the second embodiment, instead of measuring the opening degree of the bypass flow rate control valve 14 that collectively represents the thermal loads of the cooling devices 20a and 20b of the first embodiment, the cooling heat amount for cooling the electronic device is changed to the cooling heat amount. It is the structure which detects the leakage of a refrigerant | coolant for every magnitude | size of a cooling calorie, measuring with a measurement means.
Since other configurations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and description thereof is omitted.

The control of the cooling system S2 is performed by the control device C.
Specifically, the cooling device 20a is provided with a high temperature exhaust temperature sensor 27a for detecting the temperature of the high temperature exhaust 23a. Further, the cooling device 20a is provided with a cooling air temperature sensor 26a for detecting the temperature of air cooled by the high temperature exhaust 23a passing through the evaporator 21a and exchanging heat with the refrigerant.

  Similarly, the cooling device 20b is provided with a high temperature exhaust temperature sensor 27b for detecting the temperature of the high temperature exhaust 23b. Further, the cooling device 20b is provided with a cooling air temperature sensor 26b for detecting the temperature of air cooled by the high temperature exhaust 23b passing through the evaporator 21b and exchanging heat with the refrigerant.

  In the cooling system S2, instead of measuring the opening degree of the bypass flow rate control valve 14 that collectively represents the heat loads of the cooling devices 20a and 20b, the cooling heat amount is measured by the cooling heat amount measuring means (27a, 27b, 26a, 26b). To do.

  Specifically, in the cooling device 20a, the temperature t11 of the high temperature exhaust 23a is detected by the high temperature exhaust temperature sensor 27a. The cooling air temperature sensor 26a detects the temperature t12 of the air after cooling the high temperature exhaust 23a. The temperature ΔT1 at which the high temperature exhaust 23a is cooled is expressed by the following equation.

ΔT1 = t11−t12 (1)
In the cooling device 20b, the temperature t21 of the high temperature exhaust 23b is detected by the high temperature exhaust temperature sensor 27b. The cooling air temperature sensor 26b detects the temperature t22 of the air after cooling the high temperature exhaust 23b. The temperature ΔT2 at which the high temperature exhaust 23b is cooled is expressed by the following equation.
ΔT2 = t21−t22 (2)

Assuming that the cooling heat quantity Q (J) is the heat capacity C of air,
Q = CΔT (3)
The heat capacity C is defined as air mass m (g) and specific heat c (J / g · K).
C = mc (4)
It is expressed as

From equations (3) and (4),
Q = mcΔT (5)
It is expressed as

Therefore, if the mass m1 of the high temperature exhaust 23a and the mass m2 of the high temperature exhaust 23b,
The respective cooling heat amounts Q1 (J) and Q2 (J) of the cooling devices 20a and 20b are obtained from the equation (5), respectively.
Q1 = m1 · c · ΔT1 (6)
Q2 = m2 · c · ΔT2 (7)

The total cooling heat quantity Qs of the cooling devices 20a and 20b is
Qs = Q1 + Q2 (8)
It is expressed as

  Thus, the amount of cooling heat Qs in the cooling system S2 is obtained using the temperatures measured by the high temperature exhaust temperature sensors 27a and 27b and the cooling air temperature sensors 26a and 26b.

  In the same manner as in FIG. 4 of the first embodiment, first, in the cooling system S2, in the normal operation (when there is no refrigerant leakage), the liquid level of the refrigerant in the liquid tank 12 at a certain amount of cooling heat (liquid level). The threshold value for determining whether or not there is a leakage of the refrigerant is set by measuring the time (frequency (%)) during which the height is higher than a predetermined value measured by the liquid level sensor 13.

  Then, in the actual operation of the cooling system S2, whether or not the liquid level (liquid level height) of the refrigerant in the liquid tank 12 at a certain amount of cooling heat is greater than or equal to a predetermined value is measured by the liquid level sensor 13, and the liquid level of the refrigerant By measuring whether or not the operation time (frequency (%)) of the (liquid level height) is equal to or greater than a predetermined value set by the liquid level sensor 13 has reached a threshold value, the leakage of the refrigerant can be determined. it can.

According to the configuration of the second embodiment, the temperature measured by the cooling calorie measuring means (the high temperature exhaust temperature sensors 27a and 27b, the cooling air temperature sensors 26a and 26b) and the liquid level of the refrigerant in the liquid tank 12 (the liquid level). By measuring the time (frequency (%)) during which the height is higher than a predetermined value, leakage of the refrigerant in the cooling system S2 that transfers the refrigerant using the refrigerant pump 11 without using the compressor can be detected.
Therefore, it is possible to easily detect the leakage of the refrigerant in the cooling system S2 with a simple configuration.

  Therefore, when the refrigerant leakage occurs in the cooling system S2 that conveys the refrigerant by the refrigerant pump 11 without using the compressor, it is possible to detect the refrigerant leakage before the cooling capacity of the cooling devices 20a and 20b decreases. Thus, highly reliable air conditioning equipment can be provided.

<< Modification >>
In the cooling system S2 of the second embodiment, a high temperature exhaust temperature sensor that measures the temperatures of the high temperature exhausts 23a and 23b supplied to the evaporators 21a and 21b, respectively, as a cooling heat amount measuring means for measuring the cooling heat amounts of the cooling devices 20a and 20b. 27a and 27b, and cooling air temperature sensors 26a and 26b for measuring the temperature of the cooling air, respectively, have been described.
Here, the cooling calorie | heat amount measuring means should just measure the cooling calorie | heat amount of the cooling device 20a, 20b installed in one or more units | sets.

FIG. 8 shows a cooling system according to a modification of the second embodiment of the present invention.
Therefore, in the cooling system S21 of the modified example, the cold water flow temperature sensor 43 is provided on the upstream side of the chilled water pipe 42 on the primary side of the condenser 10 through which the cold water that cools the refrigerant flowing in the refrigerant gas pipe 30 flows, and the cold water return is provided on the downstream side. A temperature sensor 44 is provided.

The control of the cooling system S21 of the modified example is performed by the control device C as in the first and second embodiments.
In the cooling system S21, the heat source device 40 is controlled such that the state at the outlet of the refrigerant flowing on the secondary side of the condenser 10 is a liquid refrigerant having the same temperature.

When measuring the cooling heat amount of the cooling devices 20a and 20b in the cooling system S21, first, the cooling water flow of the heat source device 40 is determined from the difference between the measured temperature t32 of the chilled water return temperature sensor 44 and the measured temperature t31 of the chilled water traveling temperature sensor 43. The return temperature difference ΔT21 is
ΔT21 = t32−t31 (7)
I ask.

Further, the cold water flow rate is measured by a cold water flow meter 45 provided in the cold water pipe 42.
Here, the volume is obtained from the relationship of volume = cold water flow rate × time, and the mass m3 of cold water is obtained from the relationship of weight = specific gravity × volume. Assuming that the specific heat of cold water c1 (J / g · K), the cooling heat quantity Q3 is calculated from the equation (5) using the cold water forward / return temperature difference ΔT21.
Q3 = m3 · c1 · ΔT21
Is required.

Therefore, the cooling heat quantity Q3 is obtained using the chilled water forward / return temperature difference ΔT21 of the heat source device 40.
When determining whether or not the refrigerant is leaking, first, in the cooling system S21, during normal operation, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 at a certain amount of cooling heat is determined beforehand. A time (frequency (%)) for determining whether or not the refrigerant is leaking is determined by measuring a time (frequency (%)) of operation at a predetermined value or more measured by the liquid level sensor 13 and set as a threshold value. Set.

  Then, in the actual operation of the cooling system S21, the liquid level (liquid level height) of the refrigerant in the liquid tank 12 at a certain amount of cooling heat is measured by the liquid level sensor 13. Then, it is determined whether or not the ratio of the operation time (frequency (%)) when the liquid level (liquid level height) of the refrigerant is equal to or higher than a predetermined value measured by the liquid level sensor 13 has reached a threshold value. Thus, leakage of the refrigerant can be determined.

  According to the modification, the amount of cooling heat of the cooling devices 20a and 20b is obtained from the difference between the measured temperature t32 of the water return temperature sensor 44 and the measured temperature t31 of the chilled water temperature sensor 43. Then, by measuring the time (frequency (%)) in which the liquid level (liquid level height) of the refrigerant in the liquid tank 12 is operated at a predetermined value or more, the refrigerant is used by using the refrigerant pump 11 without using the compressor. It is possible to detect the leakage of the refrigerant in the cooling system S2 that transfers the refrigerant.

Therefore, it is possible to easily detect the leakage of the refrigerant in the cooling system S21 with a simple configuration.
Therefore, it becomes possible to detect the leakage of the refrigerant before the cooling capacity of the cooling devices 20a and 20b decreases, and it is possible to provide a highly reliable air conditioning facility.

  The power consumption and heat generation of the electronic devices cooled by the cooling devices 20a and 20b are measured to estimate the cooling heat amount, and are obtained as the cooling load of the cooling devices 20a and 20b. However, the leakage of the refrigerant may be determined by measuring whether or not the operation time (frequency (%)) exceeding the predetermined value measured by the liquid level sensor 13 has reached a threshold value. .

<< Other Embodiments >>
1. In the first and second embodiments and the modified examples, the case where there are two cooling devices 20a and 20b has been described as an example. However, the number of cooling devices may be singular or plural other than two. You can choose.

2. In the first and second embodiments and the modifications, the liquid level sensor 13 that measures whether or not the liquid level sensor has a predetermined height has been described as an example. You may measure the level continuously. As described above, when the liquid level sensor 13 is applied to determine whether or not the predetermined height is measured, it is most preferable because the leakage of the refrigerant can be determined at a low cost.

  In addition, this invention is not limited to above-described embodiment, Various embodiments are included. For example, the above-described embodiment is a description of the present invention in an easy-to-understand manner, and is not necessarily limited to one having all the configurations described. For example, a part of the configuration described may be included.

10 Condenser
11 Refrigerant pump
12 liquid tank
13 Liquid level sensor
14 Bypass flow control valve
20a, 20b Cooling device
21a, 21b Evaporator 22a, 22b Blower
23a, 23b High temperature exhaust (high temperature exhaust)
25a, 25b Refrigerant flow control valve
26a, 26b Cooling air temperature sensor (cooling heat amount measuring means, cooling load measuring means, high temperature exhaust temperature detecting means)
27a, 27b High temperature exhaust temperature sensor (cooling heat quantity measuring means, cooling load measuring means, high temperature exhaust temperature detecting means)
32 Bypass piping
43 Cooling water temperature sensor (cooling load measuring means, heat medium temperature detecting means)
44 Chilled water return temperature sensor (cooling load measuring means, heat medium return temperature detecting means)
C Control devices S1, S2, S21 Cooling system

Claims (7)

An evaporator that evaporates the refrigerant by heat exchange that cools the high-temperature exhaust discharged from the electronic device, a refrigerant flow control valve that adjusts the flow rate of the refrigerant liquid supplied to the evaporator, and the evaporator One or a plurality of cooling devices installed with a blower for supplying exhaust;
A condenser for liquefying the refrigerant gas vaporized by the evaporator;
A refrigerant pump for sending the refrigerant liquid liquefied in the condenser to the evaporator;
A liquid tank that is installed on the suction side of the refrigerant pump and temporarily stores the refrigerant liquid;
A bypass pipe for returning the excess refrigerant adjusted by the refrigerant flow rate control valve among the refrigerant sent by the refrigerant pump to the condenser;
A bypass flow control valve that is provided on the bypass pipe and adjusts the amount of refrigerant returned to the condenser;
A liquid level sensor for measuring the liquid level height of the refrigerant liquid in the liquid tank;
In a refrigerant leakage detection method for a cooling system comprising a control device,
The controller is
The ratio of the time during which the liquid level is operating at a predetermined height or more is calculated, and the calculated time ratio is equal to or higher than the predetermined level when there is no leakage of the refrigerant. A refrigerant leakage detection method for a cooling system, wherein it is determined that the refrigerant is leaking when the ratio is lower than a rate of time during which the operation is performed. The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes a cooling load measuring means for measuring a cooling load in the cooling device,
The controller is
During actual operation, the cooling load measuring means obtains the cooling load in the cooling device and calculates the proportion of time during which the liquid level is operating at the predetermined height or more,
Refrigerant leakage detection for a cooling system, wherein the refrigerant is determined to be leaking when the ratio of the time is less than a threshold value for determining whether or not there is refrigerant leakage at the same cooling load obtained in advance. Method. The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes a measuring instrument that measures the opening of the bypass flow control valve,
The controller is
During the actual operation, the opening of the bypass flow control valve is measured by the measuring device and the ratio of the time during which the liquid level height measured by the liquid level sensor is operated at a predetermined value or more is calculated. It is determined that the refrigerant is leaking when the time ratio is less than a threshold value for determining whether or not there is a refrigerant leak at the same opening degree of the bypass flow control valve obtained in advance. A refrigerant leak detection method for a cooling system. The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes a measuring instrument that measures the opening of the bypass flow control valve,
The controller is
When there is no refrigerant leakage, which is a threshold for determining whether there is refrigerant leakage at various opening degrees of the bypass flow control valve, the liquid level in the liquid tank is operated at a predetermined value or more. A threshold that represents the percentage of time
With the planned amount of refrigerant filled in the cooling system, various loads are applied to the cooling device during the cooling operation, and the liquid level in the liquid tank and the opening of the bypass flow control valve , And calculate the percentage of time that the liquid level in the liquid tank is operating at a predetermined value or more,
A refrigerant leakage detection method for a cooling system, wherein the refrigerant is determined to be leaking when a ratio of the time during the cooling operation is less than the threshold value at the same opening degree of the bypass flow control valve. . The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes a cooling calorie measuring means for measuring a cooling calorie in the cooling device,
The controller is
Whether the cooling heat quantity is measured by the cooling heat quantity measuring means, and the ratio at which the liquid level measured by the liquid level sensor at that time is operating at a predetermined value or higher is a refrigerant leak at the same cooling heat quantity obtained in advance. A refrigerant leakage detection method for a cooling system, wherein it is determined that there is leakage of the refrigerant when it is less than a threshold value for determining whether or not. The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes:
A cooling heat quantity measuring means for measuring the cooling heat quantity in the cooling device;
The cooling heat quantity measuring means includes a high temperature exhaust temperature detecting means for measuring the temperature of the hot exhaust gas before passing through the evaporator, and a cooling air temperature detecting means for measuring the temperature of the exhaust gas after being cooled through the evaporator. Have
The controller is
Whether the cooling heat quantity is measured by the cooling heat quantity measuring means, and the ratio at which the liquid level measured by the liquid level sensor at that time is operating at a predetermined value or higher is a refrigerant leak at the same cooling heat quantity obtained in advance. A refrigerant leakage detection method for a cooling system, wherein it is determined that there is leakage of the refrigerant when it is less than a threshold value for determining whether or not. The refrigerant leakage detection method for a cooling system according to claim 1,
The cooling system includes a cooling calorie measuring means for measuring a cooling calorie in the cooling device,
The condenser performs heat exchange between a primary side and a secondary side, a heat medium that cools the refrigerant flows through the primary side, and the refrigerant flows through the secondary side,
The cooling heat quantity measuring means measures the temperature of the heating medium before the temperature flowing through the primary side of the condenser, and the temperature of the heating medium after flowing through the primary side of the condenser. Heat medium return temperature detection means,
The controller is
Whether the cooling heat quantity is measured by the cooling heat quantity measuring means, and the ratio at which the liquid level measured by the liquid level sensor at that time is operating at a predetermined value or higher is a refrigerant leak at the same cooling heat quantity obtained in advance. A refrigerant leakage detection method for a cooling system, wherein it is determined that there is leakage of the refrigerant when it is less than a threshold value for determining whether or not.

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