JP5185541B2 - Cooling system - Google Patents

Description

  The present invention uses the cold generated by the primary refrigerant circuit using a refrigerant such as ammonia as the condensation heat of the secondary refrigerant circuit using carbon dioxide or the like as the refrigerant, and uses the cold generated by the carbon dioxide refrigerant circuit. More specifically, the present invention relates to a cooling system in which a heater defrost device is provided in a load-side cooler included in a carbon dioxide refrigerant circuit.

  Today, from the viewpoint of global environmental conservation such as prevention of ozone layer destruction and prevention of global warming, natural refrigerants are used instead of chlorofluorocarbons, which have been widely used as refrigerants, as refrigerants for indoor air conditioning and cooling / freezing of articles. However, ammonia whose ozone depletion coefficient is zero or whose global warming coefficient is zero or nearly zero is reviewed, and the adoption of refrigeration apparatuses using this ammonia as a refrigerant is increasing.

  However, since ammonia is toxic to the human body, it is not a direct refrigerant supply to the load side, but a secondary refrigerant circuit that uses carbon dioxide that is a natural refrigerant as well as non-toxic carbon dioxide as a refrigerant. A natural refrigerant cooling system configured to supply cold energy to the load side with the intervening material is put into practical use (see, for example, Patent Document 1).

  The circuit using carbon dioxide as a refrigerant described above uses the cold generated by the ammonia refrigerant circuit as condensation cold heat, liquefies carbon dioxide and stores it in a receiver, and sends this liquid refrigerant to a load-side cooler using a liquid pump. Of the refrigerant that has finished heat exchange in the load side cooler, the vaporized refrigerant is condensed via a cascade condenser and returned to the receiver, and the liquid that does not vaporize returns directly to the receiver.

  The defrosting of the frost adhering to the load side cooler in the circuit using carbon dioxide as a refrigerant is generally performed by watering defrosting, but the load side cooling by the watering defrosting is removed. The frost has a problem as described below.

  That is, since a certain amount of carbon dioxide liquid refrigerant is supplied to the load-side cooler by the liquid pump regardless of the load on the cooler, the amount of exchange heat (the amount of liquid refrigerant vaporized) decreases due to the influence of frost formation. If defrosting is performed on the load-side cooler with a large amount of liquid refrigerant in the cooler by watering defrost, the temperature of the liquid refrigerant in the load-side cooler increases due to the watering. The large amount of liquid refrigerant in the load-side cooler suddenly vaporizes, so the pressure in the circuit that uses carbon dioxide as a refrigerant rises rapidly, damaging the load-side cooler and refrigerant circuit, and liquefying carbon dioxide with a cascade capacitor. There was a fear of disappearing.

JP 2002-243350 A (pages 1 to 5, FIGS. 1 to 5)

  The present invention removes frost adhering to a load-side cooler of a secondary refrigerant circuit using a natural refrigerant such as carbon dioxide without causing a sudden pressure increase in the secondary refrigerant circuit. A cooling system that can generate frost can be provided.

  In order to solve the above-described problems, a cooling system according to 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 the cooling system generates 2 by the cold generated in the primary refrigerant circuit. In a natural refrigerant cooling system in which the refrigerant in the secondary refrigerant circuit is condensed by a cascade condenser and stored in a receiver, and the liquid refrigerant in the receiver is sent to a load-side cooler by a liquid pump, when the defroster is defrosted, the receiver The heating amount of the heater provided in the cooler is adjusted while detecting the pressure or temperature state of the liquid refrigerant in the inside, and the vaporization amount of the liquid refrigerant in the cooler due to the heating of the heater is adjusted. is there.

  Further, the heater is constituted by an electric heater, and the heating amount of the heater can be adjusted by turning on / off the electric heater, or by increasing / decreasing the heat radiation amount of the electric heater. .

  According to the cooling system of the present invention, when defrosting frost adhering to the load side cooler of the secondary refrigerant circuit during operation of the cooling system, carbon dioxide in the receiver of the secondary refrigerant circuit, etc. The frost adhering to the load-side cooler is defrosted (defrosted) by adjusting the heating amount of the heater provided in the load-side cooler while detecting the pressure or temperature state of the liquid refrigerant in which the natural refrigerant is liquefied. The temperature inside the cooler does not rise rapidly, and the liquid refrigerant inside the load side cooler does not vaporize rapidly.

  Therefore, the frost adhering to the load-side cooler can be safely defrosted without damaging the load-side cooler and the secondary refrigerant circuit using carbon dioxide as a refrigerant, and the vaporized refrigerant rapidly flows into the cascade condenser. Therefore, the primary refrigerant circuit using ammonia or the like as a refrigerant can be operated stably.

  Moreover, since the defrosting by the water spray defrost of the load side cooler in the secondary refrigerant circuit, which has been generally used so far, is made the heater defrost by the heater, facilities such as a defrost water tank and a water pipe that are necessary for the water spray defrost Therefore, it is possible to save installation costs and maintenance costs for these facilities.

  When the cooling system is suspended, the load-side cooler is provided while detecting the pressure or temperature state of the liquid refrigerant in which natural refrigerant such as carbon dioxide in the receiver is liquefied, as in the defrosting of the cooler described above. By operating the heater while adjusting the heating amount of the heater, liquid refrigerant such as carbon dioxide remaining in the load side cooler can be recovered safely and in a short time.

Hereinafter, the cooling system of the present invention will be described with reference to the accompanying drawings.
In the figure, reference numeral 1 denotes a primary refrigerant circuit in which the refrigerant is ammonia, and reference numeral 2 denotes a secondary refrigerant circuit in which the refrigerant is carbon dioxide.

  In the primary refrigerant circuit 1, the other end of the ammonia refrigerant forward pipe 5 whose one end is connected to the liquid phase 3 a of the condenser 3 that stores liquefied ammonia refrigerant that also serves as a receiver is connected to the cascade condenser via the expansion valve 4. The other end of the ammonia refrigerant return pipe 7 connected to the primary side inlet of the cascade condenser 6 and one end connected to the primary side outlet of the cascade condenser 6 is connected to the gas phase 3b of the condenser 3 via the compressor 8. Has been.

  In the secondary refrigerant circuit 2, the other end of the carbon dioxide refrigerant forward pipe 12 whose one end is connected to the liquid phase 9 a of the receiver 9 is the refrigerant of the cooler 14 via the liquid pump 10, the regulating valve 11, and the electromagnetic valve 13. The other end of the carbon dioxide refrigerant return pipe 16 connected to the inlet 14a and connected at one end to the refrigerant outlet 14b of the cooler 14 is connected to the return pipe branch 16a, and one end is connected to the return pipe branch 16a. The other end of the return pipe 17 is connected to the gas phase 9b of the receiver 9, and the other end of the via-inlet pipe 18 whose one end is connected to the return branch 16a is connected to the secondary side inlet of the cascade capacitor 6. The other end of the via / outlet pipe 19 having one end connected to the secondary outlet of the cascade capacitor 6 is connected to the gas phase 9c of the receiver 9.

  The cooler 14 is provided with an electric heater 15 for defrosting the frost adhering to the cooler 14, and the electric heater 15 is connected to a control circuit 24 through a signal line. .

  The control circuit 24 is connected to the pressure sensor 20 provided in the receiver 9 via a signal line. When the frost adhering to the cooler 14 is defrosted by the electric heater 15, the control circuit 24 24, cooling based on the internal pressure data of the receiver 9 detected by the pressure sensor 20 provided in the receiver 9 while turning on / off the power of the electric heater 15 and appropriately adjusting the heating amount by the electric heater 15 The frost adhering to the vessel 14 is defrosted (defrosted).

  That is, when the frost adhering to the cooler 14 is defrosted (defrosted), the liquid refrigerant of carbon dioxide accumulated in a liquid state without being vaporized inside the cooler 14 is heated inside the cooler 14 by heating of the electric heater 15. The vaporizer rapidly vaporizes due to the temperature rise, and the vaporized refrigerant causes the cooler 14, the carbon dioxide refrigerant return pipe 16, the direct return pipe 17 subsequent to the carbon dioxide refrigerant return pipe 16, the via inlet pipe 18, the cascade condenser 6, and the via outlet pipe. In order to prevent damage to the components of the secondary refrigerant circuit 2 system such as 19, the vaporization amount of the liquid refrigerant of carbon dioxide is adjusted by turning on / off the power supply of the electric heater 15.

  The above-described adjustment of the heating amount in the electric heater 15 is performed by adjusting the heating amount by turning on / off the power source of the electric heater 15, but the heating amount is adjusted by increasing / decreasing the heat radiation amount of the electric heater 15. May be adjusted.

  The adjustment of the heating amount in the electric heater 15 by the control circuit 24 is not shown in this embodiment, but instead of the pressure sensor 20 for detecting the internal pressure of the receiver 9, the liquid refrigerant in the receiver 9 is changed to the receiver 9. In some cases, a temperature sensor for detecting the temperature is provided, and the control circuit 24 is operated while appropriately adjusting the heating amount by the electric heater 15 based on the temperature data of the liquid refrigerant of the temperature sensor.

  A liquid level sensor 21 is connected to the receiver 9, the carbon dioxide refrigerant forward pipe 12 between the receiver 9 and the liquid pump 10, and the liquid pump 10 via a signal line. 9, the carbon dioxide refrigerant forward pipe 12 between the receiver 9 and the liquid pump 10 and the liquid amount of the liquid pump 10 are monitored.

  In addition, a temperature sensor 23 for detecting the temperature of the air-conditioned room or the like is connected to the control circuit 22 via a signal line. Based on the temperature data detected by the temperature sensor 23, the control circuit 22 causes the electromagnetic valve 13 to operate. Is adjusted.

The block diagram which shows the 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 Condenser 3a Liquid phase 3b Gas phase 4 Expansion valve 5 Ammonia refrigerant outgoing pipe 6 Cascade capacitor 7 Ammonia refrigerant return pipe 8 Compressor 9 Receiver 9a Liquid phase 9b Gas phase 9c Gas phase 10 Liquid pump 11 Adjustment valve 12 Carbon dioxide refrigerant outgoing pipe 13 Solenoid valve 14 Cooler 14a Refrigerant inlet 14b Refrigerant outlet 15 Electric heater 16 Carbon dioxide refrigerant return pipe 16a Return pipe branching section 17 Return pipe 18 Via pipe 19 Via outlet pipe 20 Pressure Sensor 21 Liquid sensor 22 Control circuit 23 Temperature sensor 24 Control circuit

Claims (2)

A primary refrigerant circuit in which ammonia is circulated as a primary refrigerant, and a secondary refrigerant circuit in which carbon dioxide is circulated as a secondary refrigerant, and the refrigerant in the secondary refrigerant circuit is cooled by the cold heat generated in the primary refrigerant circuit. In the natural refrigerant cooling system that condenses by the cascade condenser and stores in the receiver, and sends the liquid refrigerant in the receiver to the load side cooler by the liquid pump.
When defrosting the cooler, the heating amount of the heater is adjusted by turning on / off the power of the electric heater provided in the cooler while detecting the pressure or temperature state of the liquid refrigerant in the receiver. By adjusting the vaporization amount of the liquid refrigerant in the cooler due to the heating of the heater to a vaporization amount that does not rapidly vaporize , the load-side cooler and / or the refrigerant circuit can be defrosted without being damaged. Cooling system. A primary refrigerant circuit in which ammonia is circulated as a primary refrigerant, and a secondary refrigerant circuit in which carbon dioxide is circulated as a secondary refrigerant, and the refrigerant in the secondary refrigerant circuit is cooled by the cold heat generated in the primary refrigerant circuit. In the natural refrigerant cooling system that condenses by the cascade condenser and stores in the receiver, and sends the liquid refrigerant in the receiver to the load side cooler by the liquid pump.
When defrosting the cooler, the heating amount of the heater is adjusted by increasing / decreasing the heat radiation amount of the electric heater provided in the cooler while detecting the pressure or temperature state of the liquid refrigerant in the receiver. By adjusting the vaporization amount of the liquid refrigerant in the cooler due to the heating of the heater to a vaporization amount that does not rapidly vaporize , the load-side cooler and / or the refrigerant circuit can be defrosted without being damaged. Cooling system.

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