JP2007147267A - Natural refrigerant cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system that has high following capability to rapid variation of a load and can be always stably operated. <P>SOLUTION: The natural refrigerant cooling system has a primary refrigerant circuit 1 and a secondary refrigerant circuit 2, condenses the refrigerant in the secondary refrigerant circuit with cryogenic power generated by the primary refrigerant circuit, stores it in a receiver 7, and supplies the liquid refrigerant in the receiver to a cooler 9 on the load side with a liquid pump 8. This cooling system also has a pressure sensor 15 for detecting evaporating pressure of the refrigerant in the receiver 7. This cooling system also has a controlling means 18 of refrigerant supply amount that supplies a certain amount of refrigerant to the cooler when the pressure detected by the sensor is under a preset value, or reduces the refrigerant supply amount to the cooler 9 according to the increment of pressure when pressure increases with variation of the load and becomes a preset value or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has a primary refrigerant circuit and a secondary refrigerant circuit, and uses natural refrigerants such as ammonia, carbon dioxide, and water as at least one of the refrigerant in the primary refrigerant circuit and the refrigerant in the secondary refrigerant circuit. Relates to the cooling system.

  Due to the problem of global warming, the adoption of a refrigerant having a global warming potential of 0 or nearly zero is required, and there are increasing cases of using natural refrigerants such as ammonia, whose utilization technology has been established as the refrigerant.

  Since ammonia is toxic to the human body, if ammonia is supplied to the load as it is, the ammonia diffuses into the fluid to be cooled such as cooling air at the time of leakage, which is highly dangerous. Therefore, conventionally, there is a configuration in which an ammonia refrigerant circuit is installed in a limited space such as a machine room and brine is used to transfer cold heat to and from a load side cooler.

  However, in the case where cold heat is transferred by brine, a large amount of power is required for the pump for sending the brine, and the running cost increases, which cannot contribute to energy saving.

  Therefore, a secondary refrigerant circuit using another safe refrigerant such as carbon dioxide is provided separately from the ammonia refrigerant circuit, and the cold generated by the ammonia refrigerant circuit is used as cold for condensing the refrigerant in the secondary refrigerant circuit. There is an apparatus configured to supply cold heat generated in the next refrigerant circuit to a load side (see, for example, Patent Document 1).

  In the apparatus described above, the liquid refrigerant condensed by the cold heat of the ammonia refrigerant circuit as the primary refrigerant circuit is generally sent to the load-side cooler by a liquid pump, but the amount of refrigerant sent to the cooler by this liquid pump Is basically controlled to be constant.

  By the way, the amount of liquid refrigerant in the cooler changes as the load fluctuates, and in the case of a steady load, the amount of liquid refrigerant in the cooler is maintained properly and stable operation is performed, but when the load decreases The amount of refrigerant evaporated becomes small, and the amount of liquid refrigerant in the cooler increases.

  When the load suddenly increases in the above-described state, the evaporation pressure of the refrigerant increases. However, since a certain amount of liquid refrigerant is sent into the cooler by the liquid pump, the evaporation pressure of the refrigerant further increases and the secondary refrigerant The state where the operation in the circuit remains unstable is not solved.

Moreover, the increase in the evaporation pressure of the refrigerant in the secondary refrigerant circuit also affects the evaporation pressure in the primary refrigerant circuit, and the operation of the primary refrigerant circuit becomes unstable.
JP 2003-166765 A (pages 1 to 4, FIGS. 1 and 2)

  An object of the present invention is to provide a cooling system that has high followability with respect to a sudden change in load and can always be operated stably.

  In order to solve the above problems, a cooling system according to claim 1 of the present invention includes a primary refrigerant circuit and a secondary refrigerant circuit in which natural refrigerant is circulated in at least one of them, and is generated in the primary refrigerant circuit. In the natural refrigerant cooling system that condenses the refrigerant in the secondary refrigerant circuit by cold heat and stores it in the receiver, and sends the liquid refrigerant in the receiver to the load side cooler by the liquid pump, the evaporation pressure of the refrigerant in the receiver is When the pressure detected by the sensor is less than a preset value, a certain amount of refrigerant is supplied to the cooler, but the pressure increases as the load fluctuates. When the pressure becomes equal to or higher than a preset value, the refrigerant supply amount control means for reducing the refrigerant supply amount to the cooler according to the increase in pressure is provided.

  In the cooling system according to claim 2 of the present invention, the refrigerant supply amount control means includes a bypass in which one end is connected in the middle of the refrigerant between the liquid pump and the cooler, and the other end is connected to the receiver. And an automatic control valve which is provided in the middle of the bypass pipe and whose opening degree is adjusted according to the evaporation pressure of the refrigerant detected by the pressure sensor.

  In the cooling system according to claim 3 of the present invention, the refrigerant supply amount control means is an inverter that controls the rotational speed of the liquid pump according to the liquid pump and the evaporation pressure of the refrigerant detected by the pressure sensor. It is assumed that it is composed of a device.

  In the cooling system according to claim 4 of the present invention, the refrigerant supply amount control means is provided in the middle of the refrigerant between the liquid pump and the cooler, and the refrigerant evaporating pressure detected by the pressure sensor is set. It is configured with an automatic control valve whose opening is adjusted accordingly.

  According to the present invention, when the evaporation pressure of the refrigerant in the receiver increases, the amount of refrigerant supplied to the cooler is reduced, and the amount of liquid refrigerant in the cooler is properly maintained to prevent a rapid increase in evaporation pressure. Therefore, it is possible to realize a cooling system that has excellent followability to load fluctuations, and can always perform stable operation.

  In addition, since the operation of the secondary refrigerant circuit is always performed stably, there is no need to allow a large margin for the cooling capacity of the primary refrigerant circuit, and the entire system is simplified, downsized, and the running cost is reduced. be able to.

  Furthermore, since the configuration is simple and does not require a special configuration, there is a great practical advantage that it can be easily applied to an existing system.

Embodiments of the cooling system according to the present invention will be described below in detail based on specific examples shown in the accompanying drawings.
The cooling system of the present embodiment includes a primary refrigerant circuit 1 that uses ammonia as a refrigerant and a secondary refrigerant circuit 2 that uses carbon dioxide as a refrigerant.

  In the primary refrigerant circuit 1, the other end of the ammonia refrigerant forward pipe 4 connected at one end to the discharge side of the ammonia refrigerator 3 is connected to the primary side inlet of the cascade capacitor 5, and the primary side of the cascade condenser The other end of the ammonia refrigerant return pipe 6 having one end connected to the outlet is connected to the suction side of the ammonia refrigerator 3.

  The secondary refrigerant circuit 2 includes a receiver 7, a liquid pump 8, and a cooler 9, and the other end of the carbon dioxide refrigerant forward pipe 10 whose one end is connected to the liquid phase of the receiver is connected to the cooler 9 via the adjustment valve 11. The other end of the carbon dioxide refrigerant return pipe 12 is connected to the refrigerant inlet of the receiver 7 and connected to the gas phase of the receiver 7.

  The other end of the recondensing refrigerant feed pipe 13 having one end connected to the gas phase of the receiver 7 is connected to the secondary side inlet of the cascade condenser, and one end is connected to the secondary side outlet of the cascade condenser. The other end of the condensed refrigerant return pipe 14 is connected to the receiver.

  Thus, the receiver 7 is provided with a pressure sensor for detecting the evaporation pressure of the refrigerant in the receiver, and this sensor is constituted integrally with a control device 15 for sending a control signal to be described later based on the detected pressure. It is.

  In addition, the other end of the bypass pipe 16 having one end connected to the liquid pump 8 and the manual adjustment valve 11 in the carbon dioxide refrigerant forward pipe 10 is connected to the receiver 7, and in the middle of the bypass pipe, A signal line 17 from the control device 15 is connected, and an automatic adjustment valve 18 whose opening is adjusted according to the evaporation pressure of the refrigerant in the receiver detected by the pressure sensor of the control device, and a manual adjustment valve 19. Is provided.

That is, the liquid pump 8 always delivers a liquid refrigerant at a constant flow rate, and the control device 15, the bypass pipe 16, the signal line 17, and the automatic adjustment valve 18 constitute a refrigerant supply control means, and the pressure sensor of the control device When the detected pressure is less than a preset value, the automatic control valve 18 is closed and a certain amount of refrigerant is supplied to the cooler. However, the pressure increases as the load fluctuates. When the pressure exceeds a preset value, the opening of the automatic control valve 18 is increased in accordance with the increase in pressure, and the refrigerant flow rate to the bypass pipe 16 is increased so that the refrigerant does not pass through the cooler. By increasing the amount of refrigerant returned, the amount of refrigerant supplied to the cooler 9 is decreased, and thus the amount of liquid refrigerant in the cooler is appropriately maintained.
In addition, the code | symbol 20 in a figure has shown the safety valve.

  In the above-described embodiment, the amount of liquid fed by the liquid pump 8 is always kept constant regardless of the fluctuation of the load, but the bypass pipe 16 is not provided and the amount of liquid fed by the liquid pump is adjusted. And will be described with reference to FIG.

  The embodiment shown in FIG. 2 does not include the bypass pipe 16 and the adjustment valve 18 and manual adjustment valve 19 associated with the bypass pipe in the embodiment of FIG. It is configured so that the amount of liquid fed to the cooler can be controlled.

  That is, in the embodiment shown in FIG. 2, the signal line 22 from the control device 15 is connected to the inverter device 21, and the control device 15, the signal line 22, and the inverter device 21 combine the refrigerant supply control means. When the pressure detected by the pressure sensor of the control device is less than a preset value, the liquid pump 8 is driven so as to maintain a predetermined liquid supply amount. When the pressure increases and becomes equal to or higher than a preset value, the inverter device 21 decreases the driving speed of the liquid pump in accordance with the increase in pressure, and decreases the amount of refrigerant supplied to the cooler 9. By doing so, the amount of liquid refrigerant in the cooler is appropriately maintained.

  In the embodiment shown in FIG. 3, an automatic adjustment valve 23 is provided between the liquid pump 8 and the manual adjustment valve 11 in the middle of the carbon dioxide refrigerant outgoing pipe 10, and the opening degree of the automatic adjustment valve 23 is adjusted. By doing so, the amount of liquid fed to the cooler can be controlled.

  That is, in the embodiment shown in FIG. 3, the signal line 24 from the control device 15 is connected to the above-described automatic control valve 23, and the control device 15, the signal line 24, and the automatic control valve 23 The refrigerant supply control means is configured, and when the pressure detected by the pressure sensor of the control device is less than a preset value, the automatic adjustment valve 23 is fully opened or set to a preset opening degree. When the pressure increases as the load fluctuates, and the pressure exceeds a preset value, the opening of the automatic adjustment valve 23 is controlled to be small according to the increase in pressure, and the cooler 9 In this way, the amount of liquid refrigerant in the cooler is appropriately maintained.

  It should be noted that the refrigerant supply control means in the above-described embodiments may be provided individually as shown in FIGS. 1 to 3 or may be provided in combination.

  Further, in the above-described embodiment, the case where ammonia and carbon dioxide are used as the natural refrigerant has been described, but water may be used as another natural refrigerant, and in one refrigerant circuit, instead of the natural refrigerant, CFC refrigerants such as R318, R245fa, R404A, R410A, R407C, R407E, R507A, R134a may be used.

The block diagram which shows the Example of the cooling system which concerns on this invention. The block diagram which shows the other Example of the cooling system which concerns on this invention. The block diagram which shows the further another Example of the cooling system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary refrigerant circuit 2 Secondary refrigerant circuit 3 Ammonia refrigerator 4 Ammonia refrigerant outgoing pipe 5 Cascade capacitor 6 Ammonia refrigerant return pipe 7 Receiver 8 Liquid pump 9 Cooler 10 Carbon dioxide refrigerant outgoing pipe 11 Manual adjustment valve 12 Carbon dioxide refrigerant recovery Pipe 13 Recondensation refrigerant feed pipe 14 Condensed refrigerant return pipe 15 Controller 16 Bypass pipe 17 Signal line 18 Automatic adjustment valve 19 Manual adjustment valve 20 Safety valve 21 Inverter device 22 Signal line 23 Automatic adjustment valve 24 Signal line

Claims (4)

  A primary refrigerant circuit and a secondary refrigerant circuit in which natural refrigerant is circulated in at least one of them, and the refrigerant in the secondary refrigerant circuit is condensed by cold heat generated in the primary refrigerant circuit and stored in the receiver. In the natural refrigerant cooling system for sending the liquid refrigerant in the receiver to the load side cooler by the liquid pump, a pressure sensor for detecting the evaporation pressure of the refrigerant in the receiver is provided, and the pressure detected by the sensor is a preset value. When the pressure is less than the predetermined amount, a certain amount of refrigerant is supplied to the cooler. However, when the pressure increases as the load fluctuates, and this pressure exceeds a preset value, the pressure increases. A natural refrigerant cooling system comprising a refrigerant supply amount control means for reducing a refrigerant supply amount to a cooler.   The refrigerant supply amount control means is provided in the middle of the bypass pipe with one end connected in the middle between the refrigerant between the liquid pump and the cooler, and the other end connected to the receiver, The natural refrigerant cooling system according to claim 1, wherein the natural refrigerant cooling system is configured by an automatic control valve whose opening degree is adjusted according to the evaporation pressure of the refrigerant detected by the pressure sensor.   The said refrigerant | coolant supply amount control means is comprised with the said liquid pump and the inverter apparatus which performs the drive rotation speed control of the said liquid pump according to the evaporation pressure of the refrigerant | coolant detected by the said pressure sensor. Natural refrigerant cooling system.   The refrigerant supply amount control means is an automatic control valve that is provided in the middle of the refrigerant between the liquid pump and the cooler, and whose opening is adjusted according to the evaporation pressure of the refrigerant detected by the pressure sensor. The natural refrigerant cooling system according to claim 1, which is configured.

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