EP2584288A2 - Cooling System And Cooling Method - Google Patents
Cooling System And Cooling Method Download PDFInfo
- Publication number
- EP2584288A2 EP2584288A2 EP12189010.7A EP12189010A EP2584288A2 EP 2584288 A2 EP2584288 A2 EP 2584288A2 EP 12189010 A EP12189010 A EP 12189010A EP 2584288 A2 EP2584288 A2 EP 2584288A2
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- EP
- European Patent Office
- Prior art keywords
- coolant
- coolant liquid
- height
- liquid level
- storage section
- Prior art date
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- 238000001816 cooling Methods 0.000 title claims abstract description 69
- 239000002826 coolant Substances 0.000 claims abstract description 385
- 239000007788 liquid Substances 0.000 claims abstract description 305
- 238000001514 detection method Methods 0.000 claims abstract description 28
- 238000004378 air conditioning Methods 0.000 claims abstract description 7
- 238000001704 evaporation Methods 0.000 claims abstract description 4
- 230000015556 catabolic process Effects 0.000 abstract description 4
- 238000012546 transfer Methods 0.000 description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 238000000034 method Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 6
- 230000005484 gravity Effects 0.000 description 6
- 230000000630 rising effect Effects 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B23/00—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect
- F25B23/006—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect boiling cooling systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B25/00—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00
- F25B25/005—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00 using primary and secondary systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/005—Arrangement or mounting of control or safety devices of safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/03—Cavitations
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2600/00—Control issues
- F25B2600/05—Refrigerant levels
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/04—Refrigerant level
Definitions
- a cooling system which is a forced coolant circulation type that performs heat exchange between cold water in the primary cycle and coolant in the secondary cycle and circulates the coolant condensed by the heat exchange by a coolant pump.
- the liquid level sensors S1, S2 are liquid level sensors of a float switch type.
- a liquid level sensor of a float switch type opens and closes a micro switch (not shown) by the gravity and the buoyant force of a float (not shown) that moves up and down corresponding to a change in the liquid level.
- the following control may be performed. That is, when the coolant liquid level has become lower than the height H2 (S2: signal OFF) in the coolant liquid tank 6, the control device 10 drives the motor (not shown) of the coolant pump 7 at a rotation speed v2 that is lower than a rotation speed v1 of normal operation.
- control device 10 decreases the rotation speed of the motor of the coolant pump 7 step by step as the coolant liquid level in the coolant liquid tank 6 drops.
Abstract
Description
- The present invention relates to a cooling system and a cooling method for cooling indoor air that is the object of air conditioning.
- Conventionally, there is known a cooling system which is a forced coolant circulation type that performs heat exchange between cold water in the primary cycle and coolant in the secondary cycle and circulates the coolant condensed by the heat exchange by a coolant pump.
- In such a cooling system, coolant flowing into the coolant pump is desirably in a liquid state. This is because in case that the coolant flowing into the coolant pump is in a gas state, the coolant pump runs dry and may break down. This is also because in case that the coolant flowing into the coolant pump is in a state of mixed gas and liquid, the coolant pump may break down by cavitation.
- Incidentally, cavitation is a phenomenon that, adhering to an object, a bubble in liquid divides and surrounding liquid gather toward bubbles, and a strong pressure wave thereby occurs.
- Patent 1 (Translation of
PCT Application JP-T-2009-512190 - However, in the technology described in
Patent Document 1, it is possible that supply of coolant in a liquid state to a main pump is stopped, for example, when a condensing unit or the like has failed. In this case, as described above, there is a problem that the main pump breaks down by running dry or cavitation, resulting in a significant drop in the cooling capacity of the entire cooling system. - Particularly, in a data center or the like where plural servers and network devices are arranged, as heat is generated accompanying processes by respective devices, it is required to always maintain the inside of an air conditioning room at a constant temperature. That is, in a data center or the like, it is necessary to surely prevent breakdown of a main pump (coolant pump).
- In this situation, an object of the present invention is to provide a cooling system and a cooling method that enable preventing breakdown of a coolant pump.
- In order to solve an object as described above, according to the present invention, a cooling system includes: a coolant liquid detection unit for individually detecting whether or not a liquid level of coolant liquid stored in a coolant liquid storage section is higher than or equal to respective plural heights including a first height and a second height higher than the first height in the coolant liquid storage section; and a control unit that changes a rotation speed of a motor of a coolant pump, corresponding to a detection result that is input from the coolant liquid detection unit.
- According to the present invention, it is possible to provide a cooling system and a cooling method that enable preventing breakdown of a coolant pump.
-
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FIG. 1 is a configuration diagram of a cooling system in a first embodiment according to the present invention; -
FIG. 2 is a flowchart showing a process in controlling drive of a coolant pump, based on signal from liquid level sensors; -
FIG. 3 is a configuration diagram of a cooling system in a second embodiment according to the present invention; -
FIG. 4 is a configuration diagram of a cooling system in a third embodiment according to the present invention; -
FIGS. 5A and 5B are illustrations showing other examples of liquid level sensors used in cooling systems according to the invention, whereinFIG. 5A shows a case of using three liquid level sensors andFIG. 5B shows a case of using an ultrasonic sensor as a liquid level sensor. - Embodiments according to the present invention will be described below in detail with reference to the drawings, as appropriate. The same symbol will be assigned to an element common to respective drawings, and overlapping description will be omitted.
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FIG. 1 is a configuration diagram of a cooling system in a first embodiment. As shown inFIG. 1 , acooling system 100 includes a primary-side system 100a and a secondary-side system 100b. - The primary-
side system 100a includes aheat source device 1, acold storage tank 2, acold water pump 3, a three-way valve 4, and the primary-side heat-transfer tube 5h1 of acondenser 5. The secondary-side system 100b includes the secondary-side heat-transfer tube 5h2 of thecondenser 5, a coolantliquid tank 6, acoolant pump 7, and anevaporator 8. - Incidentally, the secondary-
side system 100b is not provided with a compressor or an expansion valve, and assists a natural circulation cycle by driving thecoolant pump 7, wherein, in the natural circulation cycle, coolant evaporated by theevaporator 8 moves up, and coolant condensed by thecondenser 5 moves down by gravity. - The heat source device 1 (chiller unit) supplies cold heat to the
cold storage tank 2, using for example a heat pump cycle. In case of using a heat pump cycle, theheat source device 1 is provided with a compressor (not shown), a condenser (not shown), an expansion valve (not shown), and an evaporator (not shown). - That is, in the heat pump cycle, a high temperature and high pressure coolant discharged from the compressor flows into the condenser and exchanges heat with external atmospheric air. Further, a medium temperature and high temperature coolant flows into the expansion valve from the condenser and is depressurized. Then, a low temperature and low pressure coolant flows through a
pipe 1a (seeFIG. 1 ) into a heat transfer tube (not shown) disposed in thecold storage tank 2 and evaporates by exchanging heat with water. The water is cooled by discharging heat to the coolant in the above-described heat exchange. - Incidentally, the
heat source device 1 is not limited to a heat pump cycle of a steam compression system. Otherwise, a heat source device as theheat source device 1, a heat source device which is, for example, an absorption type, an adhesion type, a thermoelectronic type, may be used, - Further, the
heat source device 1 is preferably driven, using inexpensive power at night. - A predetermined amount of water is stored in the
cold storage tank 2. The above-described heat transfer tube (not shown) is arranged in thecold storage tank 2 continuously from thepipe 1a. Then, the water in thecold storage tank 2 is cooled down to a certain temperature by heat exchange with a low temperature coolant flowing from theheat source device 1 into the above-described heat transfer tube. - The
cold water pump 3 includes a motor (not shown) therein and pressure-transmits cold water with a flow rate corresponding to the rotation speed of the motor, from thecold storage tank 2 through apipe 3a toward thecondenser 5. The rotation speed of the motor is controlled by acontrol device 10. - The three-
way valve 4 is connected with apipe 4a and apipe 4b branched from thepipe 3a. Upon instruction from thecontrol device 10, the three-way valve 4 separates a part from the cold water flowing from thepipe 4a to make the part flow in thepipe 4b in order to adjust the flow rate of cold water flowing through thepipe 3a. - The
condenser 5 includes the primary-side heat-transfer tube 5h1 whose one end communicates with thepipe 3a and whose the other end communicates with thepipe 4a, and the secondary-side heat-transfer tube 5h2 whose one end communicates with apipe 8a and whose the other end communicates with apipe 5a. Herein, in order to increase the efficiency in heat exchange between the cold water flowing through inside the primary-side heat-transfer tube 5h1 and the coolant flowing through inside the secondary-side heat-transfer tube 5h2, the primary-side heat-transfer tube 5h1 and the secondary-side heat-transfer tube 5h2 are disposed such as to contact each other. - That is, the
condenser 5 condenses the medium temperature coolant gas flowing from theevaporator 8 through thepipe 8a into the secondary-side heat-transfer tube 5h2, by cooling the coolant gas by the cold water flowing from thecold storage tank 2 through thepipe 3a into the primary-side heat-transfer tube 5h1. - The secondary-side heat-transfer tube 5h2 of the
condenser 5 is connected through thepipe 5a to the top of thecoolant liquid tank 6, and communicated with the inner space of thecoolant liquid tank 6. - The coolant
liquid tank 6 stores coolant in a liquid state flowing from thecondenser 5 and is disposed lower than thecondenser 5. That is, arrangement is made such that the coolant condensed by the condenser 5 (hereinafter, referred to as coolant liquid) moves down inside thepipe 5a by gravity and is stored in the coolantliquid tank 6. - Further, the bottom portion of the coolant
liquid tank 6 is connected through apipe 6a to a suction opening (not shown) of thecoolant pump 7. That is, arrangement is made such that, accompanying the drive (suctioning and discharging of coolant liquid) of thecoolant pump 7, coolant liquid in the coolantliquid tank 6 flows through inside thepipe 6a and moves toward the suction opening of thecoolant pump 7. - Further, as shown in
FIG. 1 , in the coolantliquid tank 6, there are provided liquid level sensors S1, S2, as coolant liquid detection units, for detecting whether or not the liquid level of coolant liquid stored in the coolantliquid tank 6 is higher than or equal to a predetermined height. - The liquid level sensors S1, S2 are liquid level sensors of a float switch type. A liquid level sensor of a float switch type opens and closes a micro switch (not shown) by the gravity and the buoyant force of a float (not shown) that moves up and down corresponding to a change in the liquid level.
- Incidentally, in the description below, the liquid level of coolant liquid stored in the coolant
liquid tank 6 may be described as 'coolant liquid level'. - As described above, in case of using liquid level sensors of a float switch type as the liquid level sensors S1, S2, the liquid level sensor S1 outputs signal ON to the control uni10 if the coolant liquid level is higher than or equal to a height H1. If a coolant liquid level is lower than the height H1, the liquid level sensor S1 outputs signal OFF to the
control unit 10. - The liquid level sensor S2 is arranged at a position (height H2) higher than the height H1 where the liquid level sensor S1 is disposed. The liquid level sensor S2 outputs signal ON to the
control unit 10 if a coolant liquid level is higher than or equal to the height H2. If a coolant liquid level is lower than the height H2, the liquid level sensor S2 outputs signal OFF to thecontrol unit 10. - That is, if the liquid level of coolant liquid stored in the
coolant liquid tank 6 is lower than the height H1, the liquid level sensors S1 and S2 respectively output signal OFF to thecontrol unit 10. - Further, if the liquid level of coolant liquid stored in the
coolant liquid tank 6 is higher than or equal to the height H1 and lower than the height H2, the liquid level sensor S1 outputs signal ON to thecontrol unit 10, and the liquid level sensor S2 outputs signal OFF to thecontrol unit 10. - Still further, if the liquid level of coolant liquid stored in the
coolant liquid tank 6 is higher than or equal to the height H2, the liquid level sensors S1 and S2 respectively output signal ON to thecontrol unit 10. - More details will be described later. In brief, the
control unit 10 stops thecoolant pump 7 when a signal from the liquid level sensor S1 has turned to OFF, and thereafter resumes driving of thecoolant pump 7 when a signal from the liquid level sensor S2 has turned to ON. - The liquid level sensors S1 and S2 (coolant liquid detection units) are arranged, as described above, at different heights H1 and H2 in the coolant liquid tank by the following reason. For example, in case that the liquid level sensor S1 is arranged at the height H1, and the liquid level sensor S2 is not arranged, signals ON/OFF, which are input from the liquid level sensor S1, are frequently switched from each other, accompanying moving up and moving down of liquid level. In this case, corresponding to ON/OFF signals input from the liquid level sensor S1, if driving and stopping of the
coolant pump 7 are frequently repeated, wasteful power consumption is caused and thecoolant pump 7 may break down. This is the reason for arranging the liquid level S2 at a different height in addition to the liquid level sensor S1. - Setting of the heights H1 and H2 will be described later.
- The coolant
pump coolant pump 7 pressure-transmits coolant liquid flowing in from thecoolant liquid tank 6 toward theevaporator 8, and is arranged lower than thecoolant liquid tank 6. Further, the discharge opening (not shown) of thecoolant pump 7 communicates through thepipe 7a with aheat transfer tube 8h of theevaporator 8. That is, accompanying the drive (suction and discharge of coolant liquid) of thecoolant pump 7, coolant liquid is pressure-transmitted through thepipe 7a toward theevaporator 8. - The
evaporator 8 evaporates coolant by heat exchange with indoor air, which is the object of air conditioning, and is arranged higher than thecoolant pump 7. Theevaporator 8 is provided with afan 9. Thefan 9 rotates, upon an instruction from thecontrol device 10, to take in high temperature air, which is in the room, and blows out the air toward theheat transfer tube 8h. Then, the high temperature air, which has been blown out toward theheat transfer tube 8h, exchanges heat (discharge heat) with low temperature coolant liquid flowing through inside theheat transfer tube 8h, and is blown out in the room as low temperature air. - On the other hand, the low temperature coolant liquid flowing through inside the
heat transfer tube 8h evaporates by heat exchange with (heat absorption from) the high temperature air and moves through thepipe 8a toward thecondenser 5. Thepipe 8a communicates with the secondary-side heat-transfer tube 5h2 of thecondenser 5. - The
control device 10 is configured with an electronic circuit including a CPU, a RAM, a ROM, and various interfaces, and integrally controls thecooling system 100. Further, thecontrol device 10 controls thecooling system 100 such that air with a certain temperature corresponding to a set temperature is blown out from theevaporator 8. - The
control device 10 controls he rotation speed of the motor (not shown) incorporated in thecold water pump 3, the opening degree of the three-way valve 4, the rotation speed of thefan 9, and the like so that air with a certain temperature is blown out from theevaporator 8. Thecontrol device 10 controls the rotation speed of the motor (not shown) incorporated in thecoolant pump 7, corresponding to inputs from the above-described liquid level sensors S1 and S2. - In the initial state of driving the
cooling system 100, coolant liquid is stored at least up to the height H2 in thecoolant liquid tank 6, and the inside of thepipe 6a, which communicates with the bottom portion of thecoolant liquid tank 6, and thepipe 7a are filled with coolant liquid. Water in thecold storage tank 2 is sufficiently cooled by theheat source device 1. - In operating the
cooling system 100, thecontrol device 10 adjusts the opening degree of the three-way valve 4 such that cold water flows with a flow rate corresponding to a set temperature into the primary-side heat-transfer tube 5h1 of thecondenser 5, and drives thecold water pump 3. Further, thecontrol device 10 rotates the motor (not shown) incorporated in thecoolant pump 7 at a predetermined rotation speed. In this case, thecoolant pump 7 sucks coolant in thepipe 6a with a pressure corresponding to the above-described rotation speed, and pressure-transmits coolant in thepipe 7a toward theevaporator 8. - Still further, the
control device 10 rotates thefan 9 at a certain rotation speed. - When the
coolant pump 7 is driven, coolant liquid in thepipe 7a is pressure-transmitted toward theheat transfer tube 8h in theevaporator 8. Herein, high temperature air (indoor air) is taken in by the rotation of thefan 9 into theevaporator 8, discharges heat by heat exchange with low temperature coolant flowing through theheat transfer tube 8h, and is blown out in the room to be low temperature air. Thus, indoor air, which is the object of air conditioning, is cooled. - On the other hand, coolant in the
heat transfer tube 8h absorbs heat by heat exchange with high temperature air, and evaporates to become medium temperature coolant gas. This coolant gas flows through inside thepipe 8a, flows into the secondary-side heat-transfer tube 5h2 of thecondenser 5, discharges heat by heat exchange with cold water flowing through in the primary-side heat-transfer tube 5h1, and thereby condenses to become low temperature coolant liquid. - Then, the above-described coolant liquid moves down in the
pipe 5a by gravity and is stored in thecoolant liquid tank 6. In such a manner, a cycle is obtained wherein coolant evaporated by theevaporator 8 is condensed by thecondenser 5, temporarily stored in thecoolant liquid tank 6, and further pressure-transmitted by thecoolant pump 7 toward theevaporator 8. - Accordingly, as long as the
cooling system 100 is free from failure, the coolant liquid level in thecoolant liquid tank 6 is maintained substantially at a constant height. - However, when a failure has occurred on the
cooling system 100, the coolant liquid level in thecoolant liquid tank 6 may drop. As an example of such a failure, there is a case that a crack is generated at a welding portion of a pipe and coolant leaks out, causing the coolant liquid level in thecoolant liquid tank 6 to drop. - As another example, there is also a case that, if temperature control by the
control device 10 is not appropriate, a part of coolant liquid does not evaporate in theevaporator 8 to remain in a liquid state, and the partial remaining coolant liquid does not return to thecoolant liquid tank 6, resulting in a drop in the coolant liquid level in thecoolant liquid tank 6. - If the
coolant pump 7 continues to drive with the above-described state continued, thecoolant pump 7 breaks down by the above-described running dry or cavitation, which causes a drop in the cooling capacity of thecooling system 100. - In order to avoid such an event, the
cooling system 100 in the present embodiment performs the following process. -
FIG. 2 is a flowchart showing a process in controlling drive of a coolant pump, based on signals from liquid level sensors. - In step S101, the
control device 10 determines whether or not a signal from the liquid level sensor S1 is OFF. If the signal from the liquid level sensor S1 is OFF (step S101 → Yes), in other words, if the coolant liquid level in thecoolant liquid tank 6 is lower than the height H1, the process by thecontrol device 10 proceeds to step S102. - If the signal from the liquid level sensor S1 is ON (step S101 → No), in other words, if the coolant liquid level in the
coolant liquid tank 6 is higher than or equal to the height H1, the process by thecontrol device 10 proceeds to step S104. - In step S102, the
control device 10 stops thecoolant pump 7. That is, thecontrol device 10 outputs a signal that makes the rotation speed of the motor zero to the above-described motor (not shown) incorporated in thecoolant pump 7. - Incidentally, a certain time is required from the time when the signal is input to the
coolant pump 7 to the time when pressure-transmission of coolant by thecoolant pump 7 completely stops. This is because a flow of coolant liquid is generated before and after thecoolant pump 7 at the time when the above-described signal is output from thecontrol device 10 and impellers (not shown) incorporated in thecoolant pump 7 continue to rotate for a while by inertia. - Accordingly, the height H1 shown in
FIG. 1 is set to a height that ensures, at the minimum, the amount in which thecoolant pump 7 transmits coolant during the time from when the liquid level sensor S1, which is arranged lower, has stopped detection of coolant liquid until pressure-transmission of coolant liquid by thecoolant pump 7 completely stops. - Incidentally, the height H1 may be set higher than the above-described height to make a larger allowance.
- In step S103, the
control device 10 determines whether or not a signal from the liquid level sensor S2 is ON. If the signal from the liquid level sensor S2 is ON (step S103 → Yes), in other words, the coolant liquid level in thecoolant liquid tank 6 is higher than or equal to the height H2, the process by thecontrol device 10 proceeds to step S104. - If the signal from the liquid level sensor S2 is OFF (step S103 → No), in other words, the coolant liquid level in the
coolant liquid tank 6 is lower than the height H2, the process by thecontrol device 10 returns to step S102. - Herein, the height H2 is set sufficiently higher than the above-described height H1. This is because, if the difference between the height H1 and the height H2 is set small, drive and stop of the
coolant pump 7 are frequently repeated, which is not desirable in a point of view of maintenance and power consumption of thecoolant pump 7. - In step S104, the
control device 10 drives thecoolant pump 7. That is, thecontrol device 10 rotates the motor (not shown) incorporated in thecoolant pump 7 at a predetermined speed. - In the
cooling system 100 in the present embodiment, thecontrol device 10 stops thecoolant pump 7 or resumes driving of thecoolant pump 7, based on signals from the liquid level sensors S1 and S2. - That is, when the liquid level of coolant stored in the
coolant liquid tank 6 becomes lower than the height H1, signal OFF is output from the liquid level sensor S1, which is arranged lower, to thecontrol device 10, and thecontrol device 10 stops thecoolant pump 7. - As described above, the height H1 is set to a height that ensures, at the minimum, the amount in which the
coolant pump 7 transmits coolant during the time from when the liquid level sensor S1, which is arranged lower, has stopped detection of coolant liquid until pressure-transmission of coolant liquid by thecoolant pump 7 completely stops. - Thus, even when a failure has occurred on the
cooling system 100, it is possible to surely supply coolant liquid from thecoolant liquid tank 6 toward thecoolant pump 7 until pressure-transmission of coolant liquid by thecoolant pump 7 stops, regardless of the cause of the failure. - Further, as described above, the height H2 where the liquid level sensor S2 is set sufficiently higher than the height H1 where the lower liquid level sensor S1 is arranged. Accordingly, by avoiding frequent repeat of drive and stop of the
coolant pump 7, it is possible to prevent thecoolant pump 7 from breaking down and reduce wasteful power consumption by thecoolant pump 7. - That is, in resuming drive of the
coolant pump 7, as coolant liquid is stored in thecoolant liquid tank 6 at least up to the height H2, it is possible to ensure a sufficient time from driving to stopping of thecoolant pump 7. - In such a manner, in the
cooling system 100 in the present embodiment, it is possible to surely prevent thecoolant pump 7 from breaking down due to running dry or cavitation. Thus, for example, in a data center or the like, it is possible to stably operate thecooling system 100, and improve the reliability of equipment. -
FIG. 3 is a configuration diagram of a cooling system in a second embodiment according to the present invention. In thecooling system 100 in the first embodiment, theevaporator 8 is arranged at a position higher than the coolant pump 7 (seeFIG, 1 ). Acooling system 100A in a second embodiment is different in that, in thecooling system 100A, anevaporator 8 is arranged lower than acoolant pump 7, and a pipe connecting thecoolant pump 7 and theevaporator 8 includes a standingcoolant tube 7b. - As the second embodiment is similar to the first embodiment in other points, only differences from the first embodiment will be described, omitting description of overlapping parts.
- The
coolant pump 7 pressure-transmits coolant liquid toward theevaporator 8, thecoolant pump 7 is accordingly, in general, disposed lower than theevaporator 8. However, depending on the conditions of the installation environment, there is a case that thecoolant pump 7 is arranged higher than theevaporator 8. - In order to handle such a case, the
cooling system 100A in the present embodiment is configured such that the pipe connecting thecoolant pump 7 and theevaporator 8 includes a standingcoolant tube 7b, wherein the standingcoolant tube 7b is extended up to a height higher than or equal to the height H2. - In the
cooling system 100A, when coolant circulation is appropriately performed, apipe 6a, the standingcoolant tube 7b, and apipe 7c are filled with coolant liquid. Coolant having evaporated by heat exchange with high temperature air in theevaporator 8 moves up in apipe 8a as coolant gas toward acondenser 5. - Herein, if a failure has occurred on the 100A and the coolant liquid level in the
coolant liquid tank 6 drops to become lower than the height H1, acontrol device 10 stops driving of thecoolant pump 7 similarly to the case described above (seeFIG, 2 ). - At this moment, as described above, the
pipe 6a, the standingcoolant tube 7b, and thepipe 7c are filled with coolant liquid. - Thereafter, coolant liquid in the
pipe 7c moves down by gravity toward theevaporator 8. On the other hand, the end portion of the coolant liquid column in the standingcoolant tube 7b is coolant whose inner liquid changes in phase, depending on the pressure state, and turns into a gas phase due to pressure distribution formed by a disposition structure including the standingcoolant tube 7b and thepipe 7c. Accordingly, the end portion of the coolant liquid column gradually moves down from the position A shown inFIG. 3 . Consequently, coolant liquid in a certain amount moves to thecoolant liquid tank 6 side such that the pressure applied to the coolant liquid column in the standingcoolant tube 7b and the pressure applied to the coolant liquid in thecoolant liquid tank 6 balance with each other. - Further, coolant liquid in a secondary-side heat-transfer tube 5h2 of the
condenser 5 flows by gravity through thepipe 5a into thecoolant liquid tank 6. - Accordingly, in case of stopping the
coolant pump 7, the coolant liquid level in thecoolant liquid tank 6 is raised by coolant liquid flowing in from the standingcoolant tube 7b and thecondenser 5. - In such a manner, the coolant liquid level in the
coolant liquid tank 6 gradually rises, and when the coolant liquid level has reached the height H2, the liquid level sensor S2 outputs signal ON to thecontrol device 10 so that thecontrol device 10 resumes driving of the coolant pump 7 (seeFIG. 2 ). - In the
cooling system 100A in the present embodiment, even in case that theevaporator 8 is arranged lower than thecoolant pump 7, it is possible to quickly raise the coolant liquid level in thecoolant liquid tank 6 upon stopping thecoolant pump 7. - Incidentally, in case that the standing
coolant tube 7b were not provided and apipe 7a (not shown) connecting thecoolant pump 7 and theevaporator 8 is arranged such as to be directed downward toward theevaporator 8, the following event occurs. That is, if the operation of thecoolant pump 7 is stopped and this state is left as it is, coolant liquid in thecoolant liquid tank 6 flows down toward theevaporator 8, which is disposed lower, and a state that coolant liquid is not stored in thecoolant liquid tank 6 occurs. In this case, as thecoolant pump 7 becomes into a state of running dry at the time of start of the next operation, a failure is thereby caused. - Different from this case, the
cooling system 100A in the present embodiment is configured such that the pipe connecting thecoolant pump 7 and theevaporator 8 includes the standingcoolant tube 7b. Accordingly, even in case that theevaporator 8 is arranged lower than thecoolant pump 7, it is possible to avoid an event that the coolant liquid level in thecoolant liquid tank 6 drops after pressure-transmission of coolant liquid by thecoolant pump 7 is stopped. - Thus, it is possible to prevent the
coolant pump 7 from breaking down due to running dry or cavitation. Further, by quickly raising the coolant liquid level in thecoolant liquid tank 6 upon stopping thecoolant pump 7, it is possible to shorten the time from the stoppage of thecoolant pump 7 to a resume of operation, and reduce a drop in the cooling capacity of thecooling system 100A. -
FIG. 4 is a configuration diagram of a cooling system in a third embodiment according to the present invention. In thecooling system 100 in the first embodiment, driving of thecoolant pump 7 is controlled, corresponding to signals from the liquid level sensors S1and S2 (seeFIG. 1 ). Acooling system 100B in the third embodiment is different in that acontrol device 10 controls driving of acoolant pump 7, corresponding to signals from adifferential pressure sensor 11. - As the third embodiment is similar to the first embodiment in other points, only differences from the first embodiment will be described, omitting description of overlapping parts.
- As shown in
FIG. 4 , acoolant liquid tank 6 is provided with thedifferential pressure sensor 11. Thedifferential pressure sensor 11 is provided with, for example, piezoelectric elements Q1, Q2 on the both sides of a diaphragm to output a difference (differential pressure) between pressures applied to the respective piezoelectric elements Q1, Q2, as a detection value. - As shown in
FIG. 4 , in thecoolant liquid tank 6, the piezoelectric element Q1 is disposed at a height lower than or equal to a height H1, and the piezoelectric element Q2 is disposed at a height higher than or equal to a height H2. As the heights H1 and H2 are similar to those described in the first embodiment, description will be omitted. - The reason for disposing the piezoelectric elements Q1 and Q2 at positions as above-described is to make it possible to detect a state that the coolant liquid level in the
coolant liquid tank 6 is the height H1 and a state that the coolant liquid level is the height H2, distinguishing these states from other states. - Incidentally, if the piezoelectric element Q1 were disposed at a position (referred to as a height H3) higher than the height H1 shown in
FIG. 1 , a detection value by thedifferential pressure sensor 11 detected when the coolant liquid level has become the height H3 and a detection value detected when the coolant liquid level has become height H1 substantially agree with each other. In this case, it is impossible for thecontrol device 10 to distinguish a state that the coolant liquid level has become the height H1 from a state that the coolant liquid level has become the height H2. - A process by the
cooling system 100B will be described below. When a detection value that is input from thedifferential pressure sensor 11 has become lower than or equal to a pressure P1 which corresponds to a state that coolant liquid is stored up to the height H1, thecontrol device 10 stops the rotation of a motor (not shown) incorporated in thecoolant pump 7. - Thereafter, when a detection value that is input from the
differential pressure sensor 11 has become higher than or equal to a pressure P2 which corresponds to a state that coolant liquid is stored up to the height H2, thecontrol device 10 resumes the rotation of the motor. - Incidentally, the above-described pressure P1, P2 are obtained by testing or the like, and are stored in advance in the storage section (not shown) of the
control device 10. - Although an example using the
differential pressure sensor 11 has been described above, arrangement may be made as follows. That is, piezoelectric elements Q1, Q2 are arranged at the respective positions shown inFIG. 4 , electric signals are output from the respective piezoelectric elements directly to thecontrol device 10, and thecontrol device 10 computes a differential pressure from these electrical signals. - By the
cooling system 100B in the present embodiment, thecontrol device 10 can control driving of thecoolant pump 7, corresponding to a detection value that is input from thedifferential pressure sensor 11. - Further, the piezoelectric elements Q1, Q2 are disposed at positions that make it possible to detect a state that the coolant liquid level in the
coolant liquid tank 6 is the height H1 and a state that the coolant liquid level is the height H2, distinguishing these states from other states. Thus, thecontrol device 10 can accurately detect whether or not the coolant liquid level in thecoolant liquid tank 6 is lower than or equal to the height H1, and whether or not the coolant liquid level is higher than or equal to the height H2. - Thus, when the coolant liquid level in the
coolant liquid tank 6 has become lower than the height H1, thecontrol device 10 can stop driving of the coolantpump coolant pump 7, and when the coolant liquid level thereafter has become higher than or equal to the height H2, thecontrol device 10 can resume driving of thecoolant pump 7. - That is, the
cooling system 100B in the present embodiment can surely prevent thecoolant pump 7 from breaking down, by making coolant in a liquid state flow from thecoolant liquid tank 6 into thecoolant pump 7. - Cooling systems according to the present invention have been described above in respective embodiments, embodiments according to the invention are not limited to the above description, and various changes and modification can be made.
- For example, in the above-described first embodiment and the second embodiment, two liquid level sensors are arranged in a
coolant liquid tank 6, however, without being limited thereto, three or more liquid level sensors may be arranged. - For example, as shown in
FIG. 5A , a liquid level sensor S3 may be arranged between the liquid level sensor S1 and the liquid level sensor S2 described in the first embodiment. - In this case, the liquid level sensors S1 to S3 respectively output a detection signal of coolant liquid to the
control device 10. In case that the liquid level sensor S1 does not detect coolant liquid and the liquid level sensor S3 does not detect coolant liquid either, thecontrol device 10 determines that the coolant liquid level is lower than the height H1 and stops driving of thecoolant pump 7. - In case that the liquid level sensor S2 has detected coolant liquid or the liquid level sensor S3 has detected coolant liquid, the
control device 10 determines that the coolant liquid level is higher than or equal to the height H2, and resumes driving of thecoolant pump 7. - In such a manner, by arranging the liquid level sensor S3 between the liquid level sensor S1 and the liquid level sensor S2 so that the
control device 10 performs control as described above, even in an event that one of the three liquid level sensors has a failure, thecontrol device 10 can control driving of thecoolant pump 7, based on signals from the other two liquid level sensors. Accordingly, thecoolant pump 7 can be further surely prevented from breaking down. - Further, although, in the above-described first to third embodiments, driving of the
coolant pump 7 is stopped when the coolant liquid level in thecoolant liquid tank 6 becomes lower than the height H1, the invention is not limited thereto. - For example, in case of using the three liquid level sensors, shown in
FIG. 5A , the following control may be performed. That is, when the coolant liquid level has become lower than the height H2 (S2: signal OFF) in thecoolant liquid tank 6, thecontrol device 10 drives the motor (not shown) of thecoolant pump 7 at a rotation speed v2 that is lower than a rotation speed v1 of normal operation. - When, the coolant liquid level in the
coolant liquid tank 6 has become lower than the height H3 (S2, S3: signal OFF), thecontrol device 10 rotates the motor at a rotation speed v3 that is lower than the rotation speed v2, and when the coolant liquid level becomes lower than the height H1 (S2, S3, S1: signal OFF) thereafter, thecontrol device 10 stops driving of thecoolant pump 7. - In such a manner, the
control device 10 decreases the rotation speed of the motor of thecoolant pump 7 step by step as the coolant liquid level in thecoolant liquid tank 6 drops. - Further, in a state of rotating the motor at the rotation speed V3, when a detection signal of coolant liquid is input from the liquid level sensor S3, the
control device 10 may control the motor to rotate at the rotation speed v2 (v2 > v3). - In such a manner, the
control device 10 increases the rotation speed of the motor of thecoolant pump 7 step by step as the coolant liquid level in thecoolant liquid tank 6 rises. - Still further, arrangement may also be made as follows. That is, the time length from when the
control device 10 has stopped driving of thecoolant pump 7 until thecontrol device 10 resumes operation of thecoolant pump 7, in other words, the time length taken by a rise in the coolant liquid level in thecoolant liquid tank 6 from the height H1 to the height H2 is measured for plural times (for example, three times), then, based on the measured plural time lengths, the average rising speed of the coolant liquid level is obtained, and based on the average rising speed, thecoolant pump 7 is continuously driven. - In this case, the
control device 10 controls the rotation speed of the motor (not shown) of thecoolant pump 7 such that the dropping speed of the coolant liquid level caused by transmission of coolant by thecoolant pump 7 becomes lower than the above-described average rising speed. - That is, the
control device 10 newly sets the rotation speed of the motor so that the amount of coolant per unit time, the coolant being pressure-transmitted by thecoolant pump 7, becomes lower than the amount of coolant liquid per unit time, the coolant liquid moving down from thecondenser 5 to thecoolant liquid tank 6. - Thus, without stopping driving of the coolant pump 7 (except during the stoppage periods of the above described plural times), it is possible to continue to send low temperature air in the room.
- Further, although, in the first embodiment and the second embodiment, the liquid level sensors S1 and S2 are arranged on the side surface of the
coolant liquid tank 6, the invention is not limited thereto. - That is, as shown in
FIG. 5B , arrangement may made as follows. That is, an ultrasonic liquid level sensor S4 is arranged on the ceiling surface of thecoolant liquid tank 6, a time length from when an ultrasonic wave is discharged from the liquid level sensor S4 until the ultrasonic wave returns back after being reflected by the liquid surface is measured, and the coolant liquid level is detected, based on the time length. - In this case, the
control device 10 compares the heights of the coolant liquid surface detected by the S4 and the above-described heights H1, H2 (, and H3), and controls driving of thecoolant pump 7, based a result of the comparison.
Claims (5)
- A cooling system (100), comprising:an evaporator (8) for evaporating a coolant by heat exchange with indoor air that is an object of air conditioning;a condenser (5) for cooling and thereby condensing the coolant evaporated by the evaporator (8);a coolant liquid storage section (6) that communicates with the condenser (5) and stores the coolant liquid flowing in from the condenser (5);a coolant pump (7) that communicates with the coolant liquid storage section (6) and pressure-transmits the coolant liquid toward the evaporator (8), the coolant liquid flowing in from the coolant liquid storage section (6);a coolant liquid detection unit (S1, S2) for individually detecting whether or not a liquid level of the coolant liquid stored in the coolant liquid storage section (6) is higher than or equal to respective plural heights including a first height (H1) and a second height (H2) higher than the first height (H1) in the coolant liquid storage section (6); anda control unit (10) that changes a rotation speed of a motor of the coolant pump (7), corresponding to a detection result that is input from the coolant liquid detection unit.
- The cooling system (100) according to claim 1,
wherein the coolant liquid detection unit (S1, S2) comprises plural liquid level sensors including a first liquid level sensor (S1) that detects whether or not coolant liquid with a liquid level higher than or equal to the first height (H1) is stored in the coolant liquid storage section (6) and a second liquid level sensor (S2) that detects whether or not coolant liquid with a liquid level higher than or equal to the second height (H2) is stored in the coolant liquid storage section (6),
and wherein the control unit (10):stops rotation of the motor when coolant liquid is not detected by the first liquid level sensor (S1); andresumes rotation of the motor when coolant liquid is detected by the second liquid level sensor (S2). - The cooling system (100B) according to claim 1,
wherein the coolant liquid detection unit (Q1, Q2) comprises a pressure difference sensor (11) arranged at the coolant liquid storage section (6),
and wherein the control unit (10):stops rotation of the motor when a detection value by the pressure difference sensor (11) has become lower than or equal to a first pressure that is a pressure at a time when coolant liquid is stored up to the first height (H1); andthereafter resumes rotation of the motor when a detection value by the pressure difference sensor (11) has become higher than or equal to a second pressure that is a pressure at a time when coolant liquid is stored up to the second height (H2). - The cooling system (100A) of any one of claims 1 to 3,
wherein a pipe connecting the coolant pump (7) and the evaporator (8) includes a standing tube (7b) that is standing up to a height higher than or equal to the second height (H2). - A cooling method for a cooling system,
wherein the cooling system includes:an evaporator (8) for evaporating a coolant by heat exchange with indoor air that is an object of air conditioning;a condenser (5) for cooling and thereby condensing the coolant evaporated by the evaporator (8);a coolant liquid storage section (6) that communicates with the condenser (5) and stores the liquid flowing in from the condenser (5);a coolant pump (7) that communicates with the coolant liquid storage section (6) and pressure-transmits the coolant liquid toward the evaporator (8), the coolant liquid flowing in from the coolant liquid storage section (6);a coolant liquid detection unit (S1, S2) for detecting whether or not a liquid level of the coolant liquid stored in the coolant liquid storage section (6) is higher than or equal to a predetermined height (H1, H2); anda control unit (10),the cooling method comprising the steps of:individually detecting whether or not the liquid level of the coolant liquid stored in the coolant liquid storage section (6) is higher than or equal to respective plural heights (H1, H2) including a first height (H1) and a second height (H2) higher than the first height (H1) in the coolant liquid storage section (6); andchanging, by the control unit (10), a rotation speed of a motor of the coolant pump (7), corresponding to a detection result that is input from the coolant liquid detection unit (S1, S2).
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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JP2011228894A JP5806581B2 (en) | 2011-10-18 | 2011-10-18 | Cooling system and cooling method |
Publications (2)
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EP2584288A2 true EP2584288A2 (en) | 2013-04-24 |
EP2584288A3 EP2584288A3 (en) | 2014-03-05 |
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EP12189010.7A Withdrawn EP2584288A3 (en) | 2011-10-18 | 2012-10-18 | Cooling System And Cooling Method |
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US (1) | US20130091880A1 (en) |
EP (1) | EP2584288A3 (en) |
JP (1) | JP5806581B2 (en) |
CN (1) | CN103062968B (en) |
SG (1) | SG189656A1 (en) |
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EP3293469A1 (en) * | 2016-09-12 | 2018-03-14 | Hamilton Sundstrand Corporation | Passive liquid collecting device |
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JP6061090B2 (en) | 2013-04-19 | 2017-01-18 | スズキ株式会社 | Control device for internal combustion engine |
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US9890983B1 (en) * | 2014-03-31 | 2018-02-13 | Robert Higgins | Step flow chiller control device and methods therefor |
JP2015230323A (en) * | 2014-06-03 | 2015-12-21 | 株式会社リコー | Cooling device and image forming apparatus |
JP6319902B2 (en) * | 2014-07-08 | 2018-05-09 | 株式会社前川製作所 | Ice rink cooling equipment and cooling method |
EP3015793B1 (en) * | 2014-10-29 | 2018-01-10 | LG Electronics Inc. | Air conditioner and method of controlling the same |
CN104567172B (en) * | 2014-12-30 | 2017-10-17 | 徐州中矿大传动与自动化有限公司 | A kind of intelligent water-cooled system with self-regulation ability |
CN107850348B (en) * | 2015-08-04 | 2021-02-02 | 开利公司 | Liquid sensing for refrigerant lubricated bearings |
CN105135570A (en) * | 2015-09-18 | 2015-12-09 | 南京佳力图空调机电有限公司 | Fluorine pump dual-circulation water cooling unit cold accumulation system |
JP6927229B2 (en) * | 2016-09-21 | 2021-08-25 | 日本電気株式会社 | Phase change cooling device and phase change cooling method |
WO2021019688A1 (en) * | 2019-07-30 | 2021-02-04 | 三菱電機株式会社 | Air conditioning device |
JP7265963B2 (en) * | 2019-08-23 | 2023-04-27 | 荏原冷熱システム株式会社 | turbo chiller |
CN113054222B (en) * | 2019-12-27 | 2022-11-18 | 未势能源科技有限公司 | Cooling system, exhaust control method and device thereof, and storage medium |
US11665866B1 (en) * | 2020-12-02 | 2023-05-30 | Amazon Technologies, Inc. | Cooling system with a booster |
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- 2012-10-18 SG SG2012077749A patent/SG189656A1/en unknown
- 2012-10-18 US US13/654,451 patent/US20130091880A1/en not_active Abandoned
- 2012-10-18 EP EP12189010.7A patent/EP2584288A3/en not_active Withdrawn
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EP3293469A1 (en) * | 2016-09-12 | 2018-03-14 | Hamilton Sundstrand Corporation | Passive liquid collecting device |
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Also Published As
Publication number | Publication date |
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SG189656A1 (en) | 2013-05-31 |
EP2584288A3 (en) | 2014-03-05 |
JP5806581B2 (en) | 2015-11-10 |
US20130091880A1 (en) | 2013-04-18 |
JP2013088027A (en) | 2013-05-13 |
CN103062968A (en) | 2013-04-24 |
CN103062968B (en) | 2015-09-02 |
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