JP2018044686A - Refrigeration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration system that can increase capacity of a refrigeration system as a whole without increasing capacity of one refrigeration device using CO2 refrigerant.SOLUTION: A refrigeration system includes: a first refrigeration device 10 using inert fluorocarbon-based refrigerant; and a plurality of second refrigeration devices 50 constituted of independent refrigerant piping system and using CO2 refrigerant. Refrigerant cooling heat exchangers 53 respectively provided to the second refrigeration devices 50 are included in an evaporator 14 of the first refrigeration device 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration system including a refrigeration apparatus using an inert fluorocarbon refrigerant and a refrigeration apparatus using a CO2 refrigerant.

Conventionally, a refrigeration apparatus using a CO2 refrigerant is known.
Since the critical temperature of the CO2 refrigerant is low (about 31 ° C.), the refrigeration apparatus using the CO2 refrigerant needs to be devised for heat radiation to the atmosphere in summer when the temperature is high. As a contrivance, there are a technique using a split cycle that cools the refrigerant by partially evaporating the refrigerant, and a technique that uses external cold water (cooling water) (see, for example, Patent Documents).

JP-A-2015-218930 JP-A-2015-218944 Japanese Patent Application Laid-Open No. 2006-01496

The freezing and refrigeration system is required to have the maximum capacity in the summer when the temperature is high, but the refrigeration system using the CO2 refrigerant having a low critical temperature (about 31 ° C.) requires the above-described device to produce the capacity in the summer. .
In addition, if the refrigeration capacity of a refrigerator is increased only with CO2 refrigerant that has not been deregulated under the High Pressure Gas Safety Law, the legal requirements will become stricter from the viewpoint of safety, and the burden of compliance with the law will increase. was there.
On the other hand, when CO2 refrigerant is cooled with brine (water or the like) to increase the refrigeration capacity, pump power is required, so the energy saving effect of the entire system cannot be expected.
The present invention has been made in view of the above-described circumstances, and provides a refrigeration system capable of ensuring a large refrigeration capacity without increasing the legal refrigeration tonnage of a refrigeration apparatus using a CO2 refrigerant. Objective.

  In order to achieve the above object, a refrigeration system according to the present invention includes a first refrigeration apparatus that uses an inert fluorocarbon-based refrigerant, and a plurality of second refrigeration apparatuses that use an independent refrigerant piping system and that use CO2 refrigerant. And each refrigerant cooling heat exchanger provided in the second refrigeration apparatus is provided in an evaporator of the first refrigeration apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerating system which can ensure a big refrigerating capacity can be provided using the freezing apparatus using the CO2 refrigerant | coolant whose legal refrigeration tonnage is below a fixed value.

The figure which shows the refrigeration system which concerns on this Embodiment

The first invention includes a first refrigeration apparatus using an inert fluorocarbon-based refrigerant that is most deregulated by the High Pressure Gas Safety Law, and a plurality of second refrigeration apparatuses using an independent refrigerant piping system and using a CO2 refrigerant, And each refrigerant cooling heat exchanger provided in the second refrigeration apparatus is provided in an evaporator of the first refrigeration apparatus.
According to this invention, it is possible to safely operate the refrigeration apparatus without increasing the burden of compliance with laws and regulations of the user. In the refrigerant cooling heat exchanger provided in the evaporator of the first refrigeration apparatus, each second refrigeration apparatus is The circulating CO2 refrigerant can be cooled.
The first refrigeration apparatus can provide a refrigeration system that can ensure a large refrigeration capacity without increasing the legal refrigeration tonnage of a plurality of independent second refrigeration apparatuses using CO2 refrigerant.
Further, when a refrigerant having a design pressure of less than 1 MPa is used in the first refrigeration apparatus using an inert fluorocarbon refrigerant, the first refrigeration apparatus itself using the inert fluorocarbon refrigerant is excluded from the application of the high-pressure gas safety law. Become.

The second invention is a refrigeration system wherein the inert fluorocarbon refrigerant has a global warming potential of less than 10.
According to this, since the inert gas refrigerant whose global warming potential is less than 10 is circulated in the first refrigeration apparatus, a safe and environment-friendly refrigeration system can be provided.

In a third aspect of the invention, the second refrigeration apparatus includes at least a compressor, a gas cooler, an expansion valve, and an evaporator, and the refrigerant cooling heat exchanger is a supercooling heat exchanger. It is.
According to the present invention, the CO2 refrigerant is cooled by the gas cooler of the second refrigeration apparatus, and is also supercooled in the evaporator of the first refrigeration apparatus, so that only the refrigeration capacity of the second refrigeration apparatus is improved. In addition, even when the first refrigeration apparatus using the inert fluorocarbon refrigerant stops, the existing second refrigeration apparatus can be operated alone.

  According to a fourth aspect of the present invention, the controller further includes a control unit, and the control unit evaporates the first refrigeration apparatus when the discharge side pressure of the compressor of the first refrigeration apparatus rises to a predetermined value that is equal to or lower than an upper limit set value. It is a refrigeration system characterized by raising the evaporation temperature of the vessel.

According to a fifth aspect of the present invention, the control unit further includes the above when the discharge side pressure of the compressor of the first refrigeration apparatus is equal to or lower than the upper limit set value and reaches a second predetermined value higher than the predetermined value. In the refrigeration system, the evaporation temperature of the evaporator of the first refrigeration apparatus is increased and the frequencies of the compressor of the first refrigeration apparatus and the compressor of the second refrigeration apparatus are decreased.
According to this invention, it is possible to prevent the discharge side pressure of the compressor in the first refrigeration apparatus using an inert fluorocarbon refrigerant having a global warming coefficient of less than 10 from exceeding a preset set value. it can.

According to a sixth aspect of the present invention, the evaporator of the first refrigeration apparatus sets the pressure in the evaporator of the first refrigeration apparatus when the pressure of the evaporator of the first refrigeration apparatus exceeds the upper limit set value. A refrigeration system comprising a safety means for keeping an upper limit set value or less.
According to this invention, even if CO2 refrigerant leaks from any one of the refrigerant cooling heat exchangers provided in the evaporator of the first refrigeration apparatus, the safety means sets the pressure in the evaporator of the first refrigeration apparatus. In order to keep below the value, it is possible to prevent the evaporator of the first refrigeration apparatus from exceeding a predetermined pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment)
FIG. 1 is a diagram showing a refrigeration system 1 according to the present embodiment.
The refrigeration system 1 includes a first refrigeration apparatus 10 that uses an inert fluorocarbon-based refrigerant having a global warming potential of less than 10, and a plurality of second refrigeration apparatuses 50 that include independent refrigerant piping systems and that use CO2 refrigerant. It has.
As the inert fluorocarbon refrigerant having a global warming potential of less than 10 used in the first refrigeration apparatus 10, an inert fluorocarbon refrigerant equivalent to ASHRAE class A1 or A2L can be used. For example, R-1234ze (E) and R-1233zd (E) are used as the inert fluorocarbon refrigerant corresponding to the ASHRAE class A1 and A2L. In the present embodiment, R-1233zd (E) refrigerant is used.
When the refrigerant used in the first refrigeration apparatus 10 is R-1233zd (E), R-1233zd (E) is an ASHRAE class A1 low toxicity and nonflammable refrigerant, and the global warming potential GWP is also 1 Because of its small size, it is possible to construct a high-efficiency system that is safe and has little environmental impact.
In addition, the refrigerant | coolant used for the 1st freezing apparatus 10 is not restricted to a thing with a global warming coefficient of less than 10, What is necessary is just an inactive fluorocarbon-type refrigerant | coolant.

An inert gas refrigerant having a global warming potential of less than 10 is a low-pressure refrigerant. Therefore, the 1st freezing apparatus 10 which concerns on this Embodiment uses the turbo refrigerator provided with the centrifugal compressor which is a compressor for low pressure refrigerant | coolants.
By using a refrigerator with a low compression ratio such as a turbo refrigerator for the first refrigeration apparatus 10 as the final source, the rated refrigeration capacity of the second refrigeration apparatus 50 using the CO2 refrigerant is reduced to 3 without reducing the total COP. Since up to 40% can be increased, the required number (number of systems) of the second refrigeration apparatus 50 can be reduced.
The high-pressure gas safety method targets a design pressure of 1 MPa or more, and when the R-1233zd (E) refrigerant is used, the design pressure of the first refrigeration apparatus 10 is less than 1 MPa. Can be exempt.

In the first refrigeration apparatus 10, a compressor (compressor of the first refrigeration apparatus) 11, a condenser 12, an expansion valve 13, and an evaporator (evaporator of the first refrigeration apparatus) 14 are connected by a series of refrigerant pipes. . The condenser 12 is provided with a fan 15.
The evaporator 14 ruptures when the pressure of the evaporator 14 exceeds the upper limit set value and keeps the pressure in the evaporator 14 so that the pressure of the evaporator 14 does not exceed the upper limit set value. Safety means) 16 is provided. For example, even if the CO 2 refrigerant of the second refrigeration apparatus 50 leaks rapidly in the supercooling heat exchanger 53 provided in the evaporator 14 of the first refrigeration apparatus 10 by the rupturable plate 16, the first refrigeration apparatus 10 It is possible to prevent the upper limit setting value from being exceeded.
As a safety measure, a safety valve may be used that opens when the pressure in the evaporator 14 exceeds the upper limit set value and adjusts the pressure in the evaporator 14 to be equal to or lower than the upper limit set value.
In the present embodiment, the upper limit set value here is set to less than 1 MPa.

The second refrigeration apparatus 50 includes a compressor pipe (compressor of the second refrigeration apparatus) 51, a gas cooler 52, a supercooling heat exchanger (refrigerant cooling heat exchanger) 53, an expansion valve 54, and an evaporator 55. Connected by.
The second refrigeration apparatus 50 includes a refrigerator 60 and a showcase 70. The compressor 51 and the gas cooler 52 are provided in the refrigerator 60. The evaporator 55 is provided in the showcase 70.
The refrigerator 60 is provided with a second fan 56 adjacent to the gas cooler. The showcase 70 is provided with a third fan 57.

A plurality of second refrigeration devices 50 are provided. Each second refrigeration device 50 includes an independent refrigerant piping system.
This second refrigeration apparatus 50 may be two or more.
In addition, the number of showcases 70 provided in each second refrigeration apparatus 50 may be one, or a plurality of showcases 70 may be provided in parallel.
In the refrigeration system 1, since each second refrigeration device 50 is composed of an independent refrigerant piping system, the refrigeration showcase 70 and the refrigeration showcase 70 can coexist.

The supercooling heat exchanger 53 is provided in the evaporator 14. The supercooling heat exchanger 53 is provided for each second refrigeration apparatus 50.
In the evaporator 14, subcooling heat exchangers 53 provided for the respective second refrigeration apparatuses 50 are independently provided in parallel.

In the present embodiment, the supercooling heat exchanger 53 is used as the refrigerant cooling heat exchanger. However, the refrigerant cooling heat exchanger is not necessarily limited to the supercooling heat exchanger 53.
Instead of providing the gas cooler 52 in the second refrigeration apparatus 50, a heat may be radiated in the evaporator 14 using a refrigerant cooling heat exchanger instead of the gas cooler 52.

  The refrigeration system 1 includes a control unit 20 including a CPU or the like as a control configuration. The control part 20 controls each part of the refrigerating system 1 collectively by reading and executing the control program installed in advance by the CPU.

The control unit 20 increases the evaporation temperature of the evaporator 14 when the discharge-side pressure of the compressor 11 reaches a predetermined value equal to or lower than the upper limit set value. At this time, for example, the control unit 20 increases the evaporation temperature of the evaporator 14 by controlling the expansion valve 13.
This is to prevent the discharge side pressure of the compressor 11 from exceeding the upper limit set value, and the predetermined value is close to the set value. In the present embodiment, the predetermined value is set to 90% of the set value.
Moreover, in this Embodiment, the upper limit set value of the discharge side pressure of the compressor 11 is set to 0.99 MPa. The predetermined evaporation temperature of the evaporator 14 is set to 18 ° C., for example. In this case, the evaporator 14 is increased by 1 ° C. and is increased to 19 ° C.

The control unit 20 further increases the evaporation temperature of the evaporator 14 when the discharge-side pressure of the compressor 11 is equal to or lower than the upper limit set value and reaches a second predetermined value higher than the predetermined value. You may control so that the frequency of the compressor 11 and the compressor 51 may be lowered | hung. At this time, for example, the control unit 20 increases the evaporation temperature of the evaporator 14 by controlling the expansion valve 13.
This is because, for example, when the above-described control is performed when the discharge-side pressure of the compressor 11 reaches 90% of a predetermined value, the discharge-side pressure of the compressor 11 continues to increase. Applied. This is to prevent the discharge side pressure of the compressor 11 from exceeding the set value, and the second predetermined value is closer to the set value than the predetermined value. In the present embodiment, for example, the second predetermined value is set to 95% of the set value.

As an example in the present embodiment, for example, when the discharge side pressure of the compressor 11 reaches 95% of the set value, the control unit 20 further increases the evaporation temperature setting of the evaporator 14 by 1 ° C. In this case, the evaporation temperature setting of the evaporator 14 is increased from 19 ° C. to 20 ° C.
The control unit 20 controls the frequency of the compressor 11 and the compressor 51 to be lowered by 5 Hz at the same time that the evaporation temperature setting of the evaporator 14 is increased from 19 ° C. to 20 ° C.
Thereby, it can suppress more reliably that the discharge side pressure of the compressor 11 exceeds 0.99 MPa which is a setting value.

Next, the operation of this embodiment will be described.
First, when the first refrigeration apparatus 10 operates the compressor 11, the R-1233zd (E) refrigerant discharged from the discharge port of the compressor 11 flows into the condenser 12. The R-1233zd (E) refrigerant flowing into the condenser 12 radiates heat in the condenser 12 and then flows into the evaporator 14. The R-1233zd (E) refrigerant that has flowed into the evaporator 14 absorbs heat in the evaporator 14 and performs heat exchange in the supercooling heat exchanger 53. The R-1233zd (E) refrigerant that has cooled the CO 2 refrigerant flowing through the supercooling heat exchanger 53 in the evaporator 14 is sucked into the suction port of the compressor 11.

  In the second refrigeration apparatus 50, when the compressor 51 is operated, the CO 2 refrigerant discharged from the discharge port of the compressor 51 flows into the gas cooler 52. The CO 2 refrigerant that has flowed into the gas cooler 52 radiates heat in the gas cooler 52, and then flows into a supercooling heat exchanger 53 provided in the evaporator 14. The CO 2 refrigerant flowing into the supercooling heat exchanger 53 further dissipates heat in the supercooling heat exchanger 53 and flows into the evaporator 55. The CO 2 refrigerant that has absorbed heat in the evaporator 55 is sucked into the suction port of the compressor 51.

The effect | action by the control part 20 is demonstrated.
When the discharge side pressure of the compressor 11 reaches 90% of the upper limit set value of 0.99 MPa, the control unit 20 controls the expansion valve 13 to change the evaporation temperature of the evaporator 14 from 18 ° C. to 19 ° C. Increase by 1 ° C.
Even when the control unit 20 performs the above control, the discharge-side pressure of the compressor 11 continues to rise, and the discharge-side pressure of the compressor 11 reaches 95% of the upper limit set value of 0.99 MPa. In this case, by controlling the expansion valve 13, the evaporation temperature of the evaporator 14 is further increased by 1 ° C. from 19 ° C. to 20 ° C., and at the same time, the frequencies of the compressor 11 and the compressor 51 are decreased by 5 Hz.

As described above, the refrigeration system 1 according to the present embodiment includes the first refrigeration apparatus 10 using R-1233zd (E) (inert fluorocarbon refrigerant) and the independent refrigerant piping system, and is a CO2 refrigerant. A plurality of second refrigeration apparatuses 50 using the respective subcooling heat exchangers (refrigerant cooling heat exchangers) 53 provided in the second refrigeration apparatus 50 in the evaporator 14 of the first refrigeration apparatus 10. Prepared.
The high-pressure gas safety method targets a design pressure of 1 MPa or more, and when the R-1233zd (E) refrigerant is used, the design pressure becomes less than 1 MPa. Become.
With this first refrigeration apparatus 10 that is excluded from the application of the high-pressure gas safety law, the plurality of second refrigeration apparatuses 50 can be operated independently without increasing the statutory refrigeration tonnage, and the statutory refrigeration tonnage is a predetermined amount or less. By operating a plurality of second refrigeration apparatuses 50, a refrigeration system 1 that can ensure a large refrigeration capacity can be provided.

  Further, according to this configuration, the CO 2 refrigerant is cooled by the gas cooler 52 and is also supercooled in the evaporator 14 of the first refrigeration apparatus 10, thereby improving the refrigeration capacity of the second refrigeration apparatus 50. Can do.

  Moreover, according to this structure, the existing 2nd freezing apparatus 50 can be provided with a supercooling heat exchanger, and can be used as it is.

  Further, according to this configuration, even when the first refrigeration apparatus 10 breaks down or is intentionally stopped, the second refrigeration apparatus 50 can operate independently.

  In addition, according to this, legal refrigeration of the first refrigeration apparatus 10 using an inert (ASHRAE class A1, A2L equivalent) low GWP (less than 10) CFC-based refrigerant whose deregulation is progressing under the High Pressure Gas Safety Law. According to the tonnage and the individual legal refrigeration tonnage (no change) of the second refrigeration apparatus 50 using the CO2 refrigerant that is independent of each other, it is possible to comply with the High Pressure Gas Safety Law.

  Further, according to this, when the first refrigeration apparatus 10 always operates at less than 1 MPa, the first refrigeration apparatus 10 is not applicable to the high-pressure gas safety law. It is possible to correspond to the high-pressure gas safety law with only the individual legal refrigeration tonnage (no change) of the two refrigeration apparatuses 50.

Moreover, according to this Embodiment, the R-1233zd (E) refrigerant | coolant used for the 1st freezing apparatus 10 is a refrigerant | coolant whose global warming coefficient is less than ten.
According to this, since the R-1233zd (E) refrigerant having a global warming potential of less than 10 is circulated in the first refrigeration apparatus 10, the refrigeration system 1 that is safe and friendly to the environment can be provided.

Further, according to the present embodiment, when the pressure of the evaporator 14 exceeds the upper limit set value 0.99 MPa, the evaporator 14 changes the pressure in the evaporator 14 to the upper limit set value 0.99 MPa. A rupture disc 16 is provided that adjusts to less than.
According to this configuration, even if CO2 refrigerant leaks from any of the plurality of subcooling heat exchangers 53 provided in the evaporator 14, the pressure in the evaporator 14 is 0.99 MPa, which is the upper limit set value. Since the rupturable plate 16 is ruptured and the pressure in the evaporator 14 is kept below the upper limit set value of 0.99 MPa, the evaporator 14 can be prevented from exceeding the upper limit set value of 0.99 MPa.

Moreover, according to this Embodiment, the refrigeration system 1 is further provided with the control part 20, and the control part 20 is 0 which is the predetermined value below 0.99 MPa whose discharge side pressure of the compressor 11 is an upper limit setting value. When 90 percent of .99 MPa is reached, the evaporation temperature of the evaporator 14 is increased by 1 ° C.
According to this, it can suppress that the discharge side pressure of the compressor 11 exceeds the preset upper limit set value.

In addition, according to the present embodiment, the control unit 20 is configured such that the discharge-side pressure of the compressor 11 is equal to or lower than the upper limit set value 0.99 MPa and is higher than 90% of the predetermined value 0.99 MPa. When 95% of the predetermined value of 0.99 MPa is reached, the evaporation temperature of the evaporator 14 is further raised by 1 ° C., and the frequencies of the compressor 11 and the compressor 51 are lowered by 5 Hz.
According to this, it can suppress more reliably that the discharge side pressure of the compressor 11 exceeds the preset upper limit set value.

Further, according to the present embodiment, R-1233zd (E) refrigerant is used for the first refrigeration apparatus 10.
According to this, when the evaporation temperature in the evaporator 14 is used at 18 ° C. or higher, the inside of the refrigerant piping system of the first refrigeration apparatus 10 does not become negative pressure, so that the risk of air leakage is reduced.

  In addition, both the R-1233zd (E) refrigerant used in the first refrigeration apparatus 10 and the CO2 refrigerant used in the second refrigeration apparatus 50 in the present embodiment are low toxic, incombustible, and global warming. Since the conversion factor is about 1, a safe and environmentally friendly refrigeration system 1 can be provided.

  As mentioned above, although this invention was demonstrated based on this Embodiment, this invention is not limited to this embodiment. Since only one embodiment of the present invention is illustrated, changes and applications can be arbitrarily made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Refrigeration system 10 1st freezing apparatus 11 Compressor (compressor of 1st freezing apparatus)
14 Evaporator (Evaporator of the first refrigeration system)
16 Rupture disc (safety means)
20 control part 50 2nd freezing apparatus 51 compressor (compressor of 2nd freezing apparatus)
52 Gas cooler 53 Supercooling heat exchanger (refrigerant cooling heat exchanger)

Claims (6)

A first refrigeration apparatus using an inert fluorocarbon refrigerant;
A plurality of second refrigeration devices comprising independent refrigerant piping systems and using CO2 refrigerant,
Each refrigerant cooling heat exchanger provided in the second refrigeration apparatus is provided in an evaporator of the first refrigeration apparatus.   The refrigeration system according to claim 1, wherein the inert fluorocarbon-based refrigerant has a global warming potential of less than 10. The second refrigeration apparatus includes at least a compressor, a gas cooler, an expansion valve, and an evaporator,
The refrigeration system according to claim 1 or 2, wherein the refrigerant cooling heat exchanger is a supercooling heat exchanger. A control unit;
The control unit increases the evaporation temperature of the evaporator of the first refrigeration apparatus when the discharge pressure of the compressor of the first refrigeration apparatus increases to a predetermined value that is equal to or lower than an upper limit set value. The refrigeration system according to any one of claims 1 to 3.   The controller further evaporates the first refrigeration apparatus when the discharge side pressure of the compressor of the first refrigeration apparatus is equal to or lower than the upper limit set value and reaches a second predetermined value higher than the predetermined value. 5. The refrigeration system according to claim 4, wherein the evaporating temperature of the refrigerator is increased and the frequencies of the compressor of the first refrigeration apparatus and the compressor of the second refrigeration apparatus are decreased.   The evaporator of the first refrigeration apparatus keeps the pressure in the evaporator of the first refrigeration apparatus below the upper limit set value when the pressure of the evaporator of the first refrigeration apparatus exceeds the upper limit set value. The refrigeration system according to any one of claims 1 to 5, further comprising safety means.

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