EP3760945A1 - Dispositif de commande de congélateur, congélateur, procédé de commande de congélateur et programme de commande de congélateur - Google Patents

Dispositif de commande de congélateur, congélateur, procédé de commande de congélateur et programme de commande de congélateur Download PDF

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Publication number
EP3760945A1
EP3760945A1 EP19782212.5A EP19782212A EP3760945A1 EP 3760945 A1 EP3760945 A1 EP 3760945A1 EP 19782212 A EP19782212 A EP 19782212A EP 3760945 A1 EP3760945 A1 EP 3760945A1
Authority
EP
European Patent Office
Prior art keywords
refrigerant
discharged
control
refrigerant temperature
compressor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19782212.5A
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German (de)
English (en)
Other versions
EP3760945A4 (fr
Inventor
Kousi TARUMA
Masakazu Kai
Kazumi Osada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Heavy Industries Thermal Systems Ltd
Original Assignee
Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Industries Thermal Systems Ltd filed Critical Mitsubishi Heavy Industries Thermal Systems Ltd
Publication of EP3760945A1 publication Critical patent/EP3760945A1/fr
Publication of EP3760945A4 publication Critical patent/EP3760945A4/fr
Pending legal-status Critical Current

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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
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • 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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/04—Refrigeration circuit bypassing means
    • F25B2400/0409—Refrigeration circuit bypassing means for the evaporator
    • 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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/04—Refrigeration circuit bypassing means
    • F25B2400/0411—Refrigeration circuit bypassing means for the expansion valve or capillary tube
    • 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
    • F25B2600/21—Refrigerant outlet evaporator temperature
    • 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
    • F25B2600/25—Control of valves
    • F25B2600/2513—Expansion valves
    • 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
    • F25B2700/21—Temperatures
    • F25B2700/2115—Temperatures of a compressor or the drive means therefor
    • F25B2700/21152—Temperatures of a compressor or the drive means therefor at the discharge side of the compressor
    • 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
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator
    • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator

Definitions

  • the present invention relates to a control device of a chiller, a chiller, a method for controlling a chiller, and a program for controlling a chiller.
  • a chiller has a larger pressure ratio between a low pressure and a high pressure during operation, as compared with an air conditioner.
  • the discharged-refrigerant temperature of the compressor is likely to rise.
  • a protective operation of lowering the discharged-refrigerant temperature is required.
  • a protection method for lowering the discharged-refrigerant temperature a discharged-refrigerant temperature protection method
  • a method of lowering the number of revolutions of the compressor to reduce the pressure ratio, or a method of bypassing part of the liquid refrigerant to the suction side of the compressor to cool the compressor is used.
  • PTL 1 discloses that the opening degree of the expansion valve is controlled to increase until the discharged-refrigerant temperature of the compressor reaches the target discharge temperature.
  • PTL 2 discloses that the opening degree of the expansion valve is increased to increase the refrigerant flow rate when the degree of superheat of the refrigerant is high, and the operation for recovering the refrigerant is ended when the discharged refrigerant temperature reaches a predetermined set value.
  • the liquid refrigerant when the liquid refrigerant is bypassed, the liquid refrigerant is returned to the compressor, so that the oil in the compressor is diluted and the lubricity may be affected. Further, in the invention disclosed above, since the liquid return amount changes due to the pressure difference between the low pressure and the high pressure, it is difficult to normally control the optimum liquid return amount.
  • the invention disclosed in PTL 1 does not disclose the condition for ending the expansion valve opening control, and it is difficult to control the chiller only by the invention disclosed in PTL 1.
  • the invention disclosed in PTL 2 is not an invention intended to protect the discharged-refrigerant temperature of the compressor, but an invention that increases the refrigerant by adding the superheating degree and takes out excess refrigerant stored in the accumulator.
  • the inventions disclosed in PTLs 1 and 2 are both inventions in an air conditioner.
  • the chiller is operated such that the pressure ratio between the low pressure and the high pressure is larger than that of the air conditioner.
  • the control of the air conditioner cannot be directly applied to the control of the chiller. It is difficult to apply the inventions disclosed in PTLs 1 and 2 to the control of the chiller.
  • the present invention has been made in view of the above circumstances, and the purpose is to provide a control device of a chiller, a chiller, a method for controlling the chiller, and a program for controlling the chiller, in which the discharged-refrigerant temperature can be preserved while suppressing capacity degradation.
  • the following means are adopted in the control device of a chiller, the chiller, the method for controlling the chiller, and the program for controlling the chiller of the present disclosure.
  • a control device of a chiller includes a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve that expands a liquid refrigerant introduced from the condenser, an opening degree of the expansion valve being controlled by using an evaporator outlet superheating degree control that controls a superheating degree of the refrigerant at an outlet of an evaporator to a value within a first predetermined range; and the evaporator that evaporates the refrigerant introduced from the expansion valve, wherein when a discharged-refrigerant temperature of the compressor exceeds a first threshold, the evaporator outlet superheating degree control is stopped, and the opening degree of the expansion valve is controlled to increase by using a discharged-refrigerant temperature protection control that controls the discharged-refrigerant temperature to a value within a second predetermined range, and when the discharged-refrigerant temperature of
  • the discharged-refrigerant temperature is controlled to be equal to or lower than the first threshold, so that the compressor can be continuously operated without being substantially stopped.
  • the refrigerant thermal energy of the refrigerant excessively supplied to the evaporator is recovered, the reduction in the refrigerating capacity can be suppressed to an extremely small level.
  • the compressor can maintain the refrigerant gas suction, the liquid refrigerant is not sucked and the oil is not diluted, so that the lubricity of the compressor is not affected.
  • the refrigerant flow rate can be finely controlled by using the expansion valve, the refrigerant flow rate can be controlled by using the minimum liquid return amount required to maintain the discharged-refrigerant temperature to be equal to or lower than the first threshold, and thus stable operation is possible.
  • the temperature protection control of the discharged refrigerant is stopped, and the opening degree of the expansion valve is controlled by the evaporator outlet superheating degree control.
  • the discharged-refrigerant temperature protection control is ended and the control is shifted to the normal evaporator outlet superheating degree control, and the discharged-refrigerant temperature of the compressor which has fallen too low by the discharged-refrigerant temperature protection control can be raised.
  • the discharged-refrigerant temperature protection control is stopped, and the opening degree of the expansion valve may be controlled to decrease by using the evaporator outlet superheating degree control.
  • the discharged-refrigerant temperature protection control is stopped, and the opening degree of the expansion valve may be controlled to decrease by using the evaporator outlet superheating degree control.
  • the discharged-refrigerant temperature protection control the discharged-refrigerant temperature of the compressor is lowered and is below the lower limit of the value at which the refrigerant superheating degree at the outlet of the evaporator is to be ensured, liquid back may occur in the compressor.
  • the opening degree of the expansion valve is controlled to decrease, it is possible to increase the refrigerant superheating degree at the outlet of the evaporator and further increase the discharged-refrigerant temperature of the compressor.
  • the opening degree of the expansion valve may be controlled to be maintained by the discharged-refrigerant temperature protection control.
  • the opening degree of the expansion valve is controlled to be maintained by the discharged-refrigerant temperature protection control.
  • the discharged-refrigerant temperature of the compressor is controlled to be within the second predetermined range of the second threshold or more and the first threshold or less, so that there is little fluctuation in the discharged-refrigerant temperature, and stable operation can be continued.
  • the capacity of the chiller can be ensured and maintained.
  • the discharged-refrigerant temperature protection control when a predetermined time or more has elapsed since the opening degree of the expansion valve is controlled by the discharged-refrigerant temperature protection control, it may be determined whether or not the discharged-refrigerant temperature of the compressor exceeds the first threshold.
  • the discharged-refrigerant temperature of the compressor when a predetermined time or more has elapsed since the opening degree of the expansion valve is controlled by the discharged-refrigerant temperature protection control, it is determined whether or not the discharged-refrigerant temperature of the compressor exceeds the first threshold.
  • the discharged-refrigerant temperature of the compressor is determined after the predetermined time has elapsed and the refrigerant circuit of the chiller enters the steady state, and thus the determination can be correctly performed.
  • the third threshold may be a value smaller than a target refrigerant superheating degree in the evaporator outlet superheating degree control.
  • the third threshold is a value smaller than the target refrigerant superheating degree in the evaporator outlet superheating degree control, the refrigerant superheating degree at the outlet of the evaporator is ensured to a minimum, and it is possible to suppress the occurrence of the liquid back in the compressor.
  • a chiller includes a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve that expands a liquid refrigerant introduced from the condenser, an opening degree of the expansion valve being controlled by using an evaporator outlet superheating degree control that controls a superheating degree of the refrigerant at an outlet of an evaporator to a value within a first predetermined range; the evaporator that evaporates the refrigerant introduced from the expansion valve; and any of the control devices described above.
  • a method for controlling a chiller is a method for controlling a chiller including a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve that expands a liquid refrigerant introduced from the condenser, an opening degree of the expansion valve being controlled by using an evaporator outlet superheating degree control that controls a superheating degree of the refrigerant at an outlet of an evaporator to a value within a first predetermined range; and the evaporator that evaporates the refrigerant introduced from the expansion valve, the method including when a discharged-refrigerant temperature of the compressor exceeds a first threshold, a step of stopping the evaporator outlet superheating degree control and controlling the opening degree of the expansion valve to increase by using a discharged-refrigerant temperature protection control that controls the discharged-refrigerant temperature to a value within a second predetermined range, and
  • a program for controlling a chiller is a program for controlling a chiller including a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve that expands a liquid refrigerant introduced from the condenser, an opening degree of the expansion valve being controlled by using an evaporator outlet superheating degree control that controls a superheating degree of the refrigerant at an outlet of an evaporator to a value within a first predetermined range; and the evaporator that evaporates the refrigerant introduced from the expansion valve, the method including when a discharged-refrigerant temperature of the compressor exceeds a first threshold, a step of stopping the evaporator outlet superheating degree control and controlling the opening degree of the expansion valve to increase by using a discharged-refrigerant temperature protection control that controls the discharged-refrigerant temperature to a value within a second predetermined range, and
  • the evaporator outlet superheating degree control is stopped and the opening degree of the expansion valve is controlled by the discharged-refrigerant temperature protection control, so that it is possible to perform a protective operation of lowering the discharged-refrigerant temperature.
  • the temperature protection control of the discharged refrigerant is stopped, and the opening degree of the expansion valve is controlled by the evaporator outlet superheating degree control, the condition for ending the discharged-refrigerant temperature protection control is clear, and the control can be stopped properly.
  • Fig. 1 illustrates a schematic configuration of one aspect of a refrigeration cycle of a chiller according to some embodiments of the present disclosure.
  • a refrigeration cycle 1 of a chiller is configured by connecting a compressor 2 that compresses a refrigerant gas introduced from an evaporator 6, a condenser 3 that condenses the high-temperature highpressure refrigerant gas which is sent from the compressor 2 and compressed by the compressor 2 by exchanging heat with the outside air, a gas-liquid internal heat exchanger (heat exchanger) 4 that supercools the liquid refrigerant, which is sent from the condenser 3 and condensed in the condenser 3, by exchanging heat with the gas refrigerant from the evaporator 6, an expansion valve 5 that expands the supercooled liquid refrigerant introduced from the gas-liquid internal heat exchanger 4, and the evaporator 6 that evaporates the refrigerant by exchanging heat between the expanded refrigerant and air in this order by a refrigerant pipe 8.
  • the evaporator 6 is used to cool the inside of the chiller.
  • the refrigeration cycle 1 is provided with a discharged-refrigerant temperature sensor 7 that detects the temperature of the refrigerant discharged from the compressor 2 (discharged-refrigerant temperature), and the detection value of the discharged-refrigerant temperature sensor 7 is input to the control device 10.
  • the control device 10 has a function of adjusting the opening degree of the expansion valve 5 such that the refrigerant superheating degree at the outlet of the evaporator 6 is controlled to "a value in a first predetermined range including the target refrigerant superheating degree".
  • a target refrigerant superheating degree that is a control target value of the refrigerant superheating degree is set.
  • the control device 10 controls the refrigerant superheating degree at the outlet of the evaporator 6 to be a value in a first predetermined range including the target refrigerant superheating degree.
  • the control of the refrigerant superheating degree is performed by the control device 10 adjusting the opening degree of the expansion valve 5. For example, when increasing the refrigerant superheating degree, the opening degree of the expansion valve 5 is controlled to decrease. When reducing the refrigerant superheating degree, the opening degree of the expansion valve 5 is controlled to increase.
  • the target refrigerant superheating degree is 7°C.
  • the control device 10 includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a computer-readable non-transitory storage medium, and the like.
  • CPU central processing unit
  • RAM random access memory
  • ROM read only memory
  • a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program as an example.
  • the CPU reads the program to a RAM or the like and to process information and executes a calculation process, thereby realizing various functions.
  • the program may be installed in advance in a ROM or other storage medium, may be provided in a state stored in a computer readable storage medium, or may be distributed through wired or wireless communication means.
  • the computer-readable storage medium is a magnetic disk, a magnetooptical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.
  • the chiller has a larger pressure ratio between the low pressure and the high pressure during operation, as compared with the air conditioner. In such a high pressure ratio operation with a large pressure ratio, the discharged-refrigerant temperature of the compressor 2 is likely to rise.
  • the compressor 2 has an upper limit in the temperature at which the compressor 2 can operate, and this is set as the upper limit of the allowable temperature of the compressor. Therefore, under operating conditions in which the discharged-refrigerant temperature measured by the discharged-refrigerant temperature sensor 7 exceeds the upper limit of the allowable temperature of the compressor of the compressor 2, a protective operation of lowering the discharged-refrigerant temperature is required.
  • a control upper limit (first threshold), of the discharged-refrigerant temperature which is lower than the upper limit of the allowable temperature of the compressor by a predetermined temperature is provided.
  • the discharged-refrigerant temperature protection control is performed in some embodiments of the present disclosure.
  • the control upper limit of the discharged-refrigerant temperature is, for example, the upper limit of the allowable temperature of the compressor - 15°C.
  • a control lower limit of the discharged-refrigerant temperature is set as a second threshold smaller than the control upper limit of the discharged-refrigerant temperature.
  • the control lower limit of the discharged-refrigerant temperature is, for example, the control upper limit of the discharged-refrigerant temperature - 35°C.
  • the control lower limit of the discharged-refrigerant temperature is a temperature serving as a standard for determining that the temperature of the compressor 2 is extremely low when the discharged-refrigerant temperature is below the control lower limit of the discharged-refrigerant temperature value, and for raising the temperature of the compressor 2.
  • the discharged-refrigerant temperature protection control is to control the discharged-refrigerant temperature to a value within the second predetermined range.
  • the second predetermined range is a range from the control lower limit (second threshold) of the discharged-refrigerant temperature to the control upper limit (first threshold) of the discharged-refrigerant temperature.
  • the control device 10 controls the opening degree of the expansion valve 5 such that the discharged-refrigerant temperature measured by the discharged-refrigerant temperature sensor 7 becomes a value within the second predetermined range.
  • the control lower limit of the discharged-refrigerant temperature is a value smaller than the control upper limit of the discharged-refrigerant temperature.
  • Fig. 2 is a flowchart illustrating control of the control device of a chiller according to some embodiments of the present disclosure.
  • step S201 When the control of the control device 10 is started, it is determined whether the compressor discharged-refrigerant temperature (Td) protection control is being performed (S201). When it is determined that the compressor discharged-refrigerant temperature protection control is being performed, the process proceeds to step S202, and when it is determined that it is not being performed, the process proceeds to step S208.
  • Td compressor discharged-refrigerant temperature
  • step S202 it is determined whether or not a predetermined time or more has elapsed after the opening degree of the expansion valve 5 was changed in the previous process.
  • the opening degree of the expansion valve 5 is changed, there is a time lag until the refrigerant circuit of the refrigeration cycle 1 reaches a steady state. Therefore, the time period in which the refrigerant circuit is predicted to be in the steady state is set to a predetermined time period, and it is determined whether or not the predetermined time period has elapsed.
  • step S203 When a predetermined time or more has elapsed after changing the opening degree, the process proceeds to step S203, and when the predetermined time has not elapsed, the process is temporarily ended and the process is performed again from the beginning.
  • step S202 When it is determined in step S202 that the predetermined time or more has elapsed after the opening degree of the expansion valve 5 was changed, it is determined whether or not the compressor discharged-refrigerant temperature, which is the detection value of the discharged-refrigerant temperature sensor 7, exceeds the control upper limit (first threshold) of the discharged-refrigerant temperature (S203).
  • step S203 When it is determined in step S203 that the compressor discharged-refrigerant temperature exceeds the control upper limit of the discharged-refrigerant temperature, the process proceeds to step S210. On the other hand, when it is determined that the compressor discharged-refrigerant temperature is equal to or lower than the control upper limit of the discharged-refrigerant temperature, the process proceeds to step S204.
  • step S203 When it is determined in step S203 that the compressor discharged-refrigerant temperature exceeds the control upper limit of the discharged-refrigerant temperature, the opening degree of the expansion valve 5 is increased by a predetermined amount (S210).
  • the control device 10 controls the opening degree of the expansion valve 5 to increase by a predetermined amount.
  • the flow rate of the refrigerant circulating in the refrigeration cycle 1 increases, and the compressor discharged-refrigerant temperature decreases. In this case, the refrigerant superheating degree at the outlet of the evaporator 6 also decreases.
  • step S210 When the opening degree of the expansion valve 5 is increased by a predetermined amount in step S210, the process is temporarily ended, and the process is performed again from the beginning.
  • step S203 when it is determined in step S203 that the compressor discharged-refrigerant temperature is equal to or lower than the control upper limit of the discharged-refrigerant temperature, it is determined whether or not the compressor discharged-refrigerant temperature is equal to or greater than the lower limit (second threshold) of the discharged-refrigerant temperature control (S204).
  • step S204 When it is determined in step S204 that the compressor discharged-refrigerant temperature is equal to or greater than the control lower limit of the discharged-refrigerant temperature, the process is temporarily ended while the control is performed so as to maintain the opening degree of the expansion valve 5, and the process is performed again from the beginning.
  • step S204 when it is determined in step S204 that the compressor discharged-refrigerant temperature is below the control lower limit of the discharged-refrigerant temperature, the process proceeds to step S205.
  • step S205 the refrigerant superheating degree at the outlet of the evaporator 6 is determined.
  • the control lower limit (third threshold) of the refrigerant superheating degree the process transitions to step S206.
  • the process transitions to step S211.
  • the control lower limit (third threshold) of the refrigerant superheating degree is a value to be ensured at a minimum in the refrigerant superheating degree at the outlet of the evaporator 6 in order to use the evaporator 6 efficiently.
  • the control lower limit of the refrigerant superheating degree is a value smaller than the target refrigerant superheating degree, and for example, the target refrigerant superheating degree - 2°C is set.
  • step S207 When the evaporator outlet superheating degree control is started in step S207, the process is temporarily ended, and the process is performed again from the beginning.
  • the opening degree of the expansion valve 5 is reduced by a predetermined amount (S211).
  • the control device 10 controls the opening degree of the expansion valve 5 to decrease by a predetermined amount.
  • the flow rate of the refrigerant circulating in the refrigeration cycle 1 is reduced, and the discharged-refrigerant temperature of the compressor and the refrigerant superheating degree at the outlet of the evaporator 6 are increased.
  • step S211 When the opening degree of the expansion valve 5 is reduced by a predetermined amount in step S211, the process is temporarily ended, and the process is performed again from the beginning.
  • the compressor discharged-refrigerant temperature protection control is performed.
  • step S201 When it is determined in step S201 that the compressor discharged-refrigerant temperature protection control is not performed, it is determined whether or not the compressor discharged-refrigerant temperature, which is the detection value of the discharged-refrigerant temperature sensor 7, exceeds the control upper limit (first threshold) of the discharged-refrigerant temperature (S208).
  • step S208 When it is determined in step S208 that the compressor discharged-refrigerant temperature exceeds the control upper limit of the discharged-refrigerant temperature, the process proceeds to step S209. On the other hand, when it is determined that the compressor discharged-refrigerant temperature is equal to or lower than the control upper limit of the discharged-refrigerant temperature, the process proceeds to step S207.
  • step S208 When it is determined in step S208 that the compressor discharged-refrigerant temperature exceeds the control upper limit of the discharged-refrigerant temperature, the compressor discharged-refrigerant temperature protection control is started (S209) and the opening degree of the expansion valve 5 is increased by a predetermined amount (S210).
  • the control device 10 controls the opening degree of the expansion valve 5 to increase by a predetermined amount.
  • the flow rate of the refrigerant circulating in the refrigeration cycle 1 increases, and the compressor discharged-refrigerant temperature decreases. In this case, the refrigerant superheating degree at the outlet of the evaporator 6 also decreases.
  • step S210 When the opening degree of the expansion valve 5 is increased by a predetermined amount in step S210, the process is temporarily ended, and the process is performed again from the beginning.
  • step S207 evaporator outlet superheating degree control is performed (S207).
  • the evaporator outlet superheating degree control is started in step S207, the process is temporarily ended, and the process is performed again from the beginning.
  • the steps S201, S208, and S207 are performed in this order in the flowchart of Fig. 2 .
  • the refrigeration cycle 51 of the chiller as a reference example includes a liquid bypass line 59 that connects the outlet side of the condenser 53 and the inlet side of the compressor 52.
  • the chiller as a reference example cools the compressor 52 by performing the liquid bypass control so as to bypass the liquid refrigerant to the inlet side of the compressor 52.
  • control device 50 performs liquid bypass control.
  • Fig. 4 is a graph illustrating a change in a discharged-refrigerant temperature in the chiller as the reference example.
  • the vertical axis represents the discharged-refrigerant temperature of the compressor 52, and the horizontal axis represents time.
  • a indicates a liquid bypass control end temperature to be described later
  • b indicates the control upper limit of the discharged-refrigerant temperature
  • c indicates the upper limit of the allowable temperature of the compressor.
  • the discharged-refrigerant temperature of the compressor 52 rises and reaches the control upper limit b of the discharged-refrigerant temperature at time t1.
  • the control device 50 starts the liquid bypass control and opens the liquid bypass line 59. Since there is a time lag to start lowering the discharged-refrigerant temperature of the compressor 52 after the liquid bypass control is started, the discharged-refrigerant temperature starts to decrease after a lapse of a predetermined time after the time t1.
  • An end temperature is set for the liquid bypass control, and this is set as a liquid bypass control end temperature a.
  • a liquid bypass control end temperature a At time t2, when the discharged-refrigerant temperature reaches the liquid bypass control end temperature a, the liquid bypass line 59 is closed and the liquid bypass control ends.
  • the discharged-refrigerant temperature starts to decrease after a lapse of a predetermined time after the time t2.
  • the start and end are alternately and continuously performed such that when the discharged-refrigerant temperature reaches the control upper limit b of the discharged-refrigerant temperature at time t3, the liquid bypass control is started, and when the discharged-refrigerant temperature reaches the liquid bypass control end temperature a at time t4, the liquid bypass control is ended.
  • the temperature change of the discharged refrigerant temperature is large. Therefore, the discharged-refrigerant temperature frequently reaches the control upper limit b of the discharged-refrigerant temperature and the liquid bypass control end temperature a, and the control is switched in a short time. Since the liquid refrigerant is bypassed from the outlet of the condenser 53 to the inlet of the compressor 52, the amount of refrigerant flowing into the evaporator 56 is small, and the reduced amount of refrigerant does not contribute to the refrigeration function.
  • Fig. 5 is a graph illustrating a change in a discharged-refrigerant temperature in a chiller according to some embodiments of the present disclosure.
  • the vertical axis represents the discharged-refrigerant temperature of the compressor 52, and the horizontal axis represents time.
  • d indicates a control lower limit (second threshold) of the discharged-refrigerant temperature to be described later
  • b indicates a control upper limit (first threshold) of the discharged-refrigerant temperature
  • c indicates an upper limit of the allowable temperature of the compressor.
  • the evaporator outlet superheating degree control is being performed.
  • the discharged-refrigerant temperature of the compressor 2 rises and reaches the control upper limit b of the discharged-refrigerant temperature at time t7.
  • the evaporator outlet superheating degree control is stopped and the discharged-refrigerant temperature protection control is started.
  • the discharged-refrigerant temperature protection control is to control the discharged-refrigerant temperature to a value within the second predetermined range.
  • the control device 10 controls the opening degree of the expansion valve 5 such that the discharged-refrigerant temperature measured by the discharged-refrigerant temperature sensor 7 becomes a value in a second predetermined range which is a range from the control lower limit (second threshold) d of the discharged-refrigerant temperature to the control upper limit (first threshold) b of the discharged-refrigerant temperature.
  • the opening degree of the expansion valve 5 is controlled to increase. Since there is a time lag to start lowering the discharged-refrigerant temperature of the compressor 2 after the opening degree of the expansion valve 5 is controlled to increase, the discharged-refrigerant temperature starts to decrease after a lapse of a predetermined time after the time t7.
  • the discharged-refrigerant temperature of the compressor 2 is controlled such that a large fluctuation is suppressed and so as to change within the second predetermined range. According to some embodiments of the present disclosure, stable operation can be continued.
  • the difference between the liquid bypass control end temperature a and the control upper limit b of the discharged-refrigerant temperature is made large in order to avoid frequent turning on and off of the liquid bypass control.
  • the refrigerant flow rate can be finely controlled by using the expansion valve 5. It is possible to control to the minimum liquid return amount required to maintain the discharged-refrigerant temperature equal to or lower than the allowable temperature upper limit of the compressor.
  • the difference between the control lower limit d of the discharged-refrigerant temperature and the control upper limit b of the discharged-refrigerant temperature can be reduced. Since the level of the discharged refrigerant temperature is proportional to the level of the capacity of the chiller, changing the discharged refrigerant temperature to a high value also changes the capacity of the chiller to a high value.
  • Fig. 6 is a graph illustrating a change in refrigerating capacity of a chiller as a reference example.
  • the vertical axis represents the refrigerating capacity of the chiller
  • the horizontal axis represents the intake air temperature of the condenser.
  • the intake air temperature of the condenser is approximately equal to the ambient temperature.
  • R1 indicates refrigerating capacity when switching from evaporator outlet superheating degree control to discharged-refrigerant temperature protection control (in this case, liquid bypass control) at the intake air temperature T1
  • R2 indicates refrigerating capacity at the intake air temperature T2.
  • the solid line shows the relationship between the refrigerating capacity and the intake air temperature of the condenser.
  • the dot-dashed line shows the change of the refrigerating capacity that is expected when the normal evaporator outlet superheating degree control is performed.
  • the refrigerating capacity R2 when the intake air temperature rises and becomes the intake air temperature T2 is greatly reduced.
  • the discharged-refrigerant temperature protection control needs to be performed normally, and the liquid bypass line 59 is normally opened.
  • Fig. 7 is a graph illustrating changes in refrigerating capacity in the chiller according to some embodiments of the present disclosure.
  • the vertical axis represents the refrigerating capacity of the chiller
  • the horizontal axis represents the intake air temperature of the condenser.
  • R1 indicates refrigerating capacity when switching from evaporator outlet superheating degree control to discharged-refrigerant temperature protection control at the intake air temperature T1
  • R3 indicates refrigerating capacity at the intake air temperature T2.
  • the solid line shows the relationship between the refrigerating capacity and the intake air temperature of the condenser.
  • the dot-dashed line shows the change of the refrigerating capacity that is expected when the normal evaporator outlet superheating degree control is performed.
  • the refrigerating capacity R3 when the intake air temperature rises and becomes the intake air temperature T2 is reduced, but there is little decrease in the refrigerating capacity. This is because, as shown in Fig. 5 , there is little decrease in the discharged-refrigerant temperature.
  • R3 is a value larger than the refrigerating capacity R2 when the intake air temperature becomes the intake air temperature T2 in the chiller as the reference example shown in Fig. 6 .
  • Fig. 8 is a pressure-enthalpy diagram in a chiller as the reference example.
  • the vertical axis represents pressure and the horizontal axis represents enthalpy.
  • the thick solid line indicates the refrigeration cycle during the evaporator outlet superheating degree control, and the thick broken line indicates the isothermal curve during the evaporator outlet superheating degree control.
  • the solid line indicates the refrigeration cycle during liquid bypass control, and the broken line indicates the isothermal curve during liquid bypass control.
  • the dot-dashed line indicates the saturation curve.
  • h1 indicates the gas refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h3 indicates the liquid refrigerant inlet of the gas-liquid internal heat exchanger 54
  • h4 indicates the liquid refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h6 indicates the gas refrigerant inlet of the gas-liquid internal heat exchanger 54.
  • h1' indicates the gas refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h3' indicates the liquid refrigerant inlet of the gas-liquid internal heat exchanger 54
  • h4' indicates the gas refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h6' indicate the gas refrigerant inlet of the gas-liquid internal heat exchanger 54.
  • Fig. 9 is a pressure-enthalpy diagram in a chiller according to some embodiments of the present disclosure.
  • the vertical axis represents pressure and the horizontal axis represents enthalpy.
  • the thick solid line indicates the refrigeration cycle during the evaporator outlet superheating degree control, and the thick broken line indicates the isothermal curve during the evaporator outlet superheating degree control.
  • the solid line indicates the refrigeration cycle during the discharged-refrigerant temperature protection control, and the broken line indicates the isothermal curve during the discharged-refrigerant temperature protection control.
  • the dot-dashed line indicates the saturation curve.
  • h1 indicates the gas refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h3 indicates the liquid refrigerant inlet of the gas-liquid internal heat exchanger 54
  • h4 indicates the liquid refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h6 indicates the gas refrigerant inlet of the gas-liquid internal heat exchanger 54.
  • h1" indicates the gas refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h3" indicates the liquid refrigerant inlet of the gas-liquid internal heat exchanger 54
  • h4" indicates the liquid refrigerant outlet of the gas-liquid internal heat exchanger 54
  • h6 indicate the gas refrigerant inlet of the gas-liquid internal heat exchanger 54.
  • the discharged-refrigerant temperature and the refrigerating capacity when the control is switched from the normal evaporator outlet superheating degree control to the discharged-refrigerant temperature protection control, the discharged-refrigerant temperature and the refrigerating capacity also decrease.
  • the isothermal curve (thick broken line) showing the discharged-refrigerant temperature in the evaporator outlet superheating degree control moves to the isothermal curve (broken line) showing the discharged-refrigerant temperature in the liquid bypass control, and this moving distance is represented as a temperature difference of the discharged-refrigerant temperature.
  • the isothermal curve (thick broken line) showing the discharged-refrigerant temperature in the evaporator outlet superheating degree control moves to the isothermal curve (broken line) showing the discharged-refrigerant temperature in the discharged-refrigerant temperature protection control, and this moving distance is represented as a temperature difference of the discharged-refrigerant temperature.
  • the discharged-refrigerant temperature of the compressor 2 can be reduced to the temperature required to maintain the temperature below the upper limit or less.
  • the chiller According to the chiller according to some embodiments of the present disclosure, it is possible to suppress a decrease in the discharged-refrigerant temperature as compared with the liquid bypass control.
  • the refrigerant evaporation temperature rises from h1 to h1' or from h6 to h6' by the difference x'. Therefore, the refrigerating capacity corresponding to the difference x' is reduced.
  • the liquid refrigerant is bypassed from h3' to h1', so that the refrigerating capacity corresponding to the difference y (two-dot chain line portion) between h3' and h1' is reduced.
  • the refrigerating capacity corresponding to x' + y decreases.
  • the refrigerant evaporation temperature rises from h1 to h1", or from h6 to h6" by the difference x". Therefore, the refrigerating capacity corresponding to the difference x" decreases.
  • the decrease in the refrigerating capacity of the chiller according to some embodiments of the present disclosure is less than the decrease in the capacity during liquid bypass control. According to the chiller according to some embodiments of the present disclosure, it is possible to suppress a decrease in the refrigerating capacity to be small.
  • the control device of a chiller the chiller, the method for controlling a chiller, and the program for controlling a chiller according to the present embodiment, the following operational effects are achieved.
  • the discharged-refrigerant temperature is controlled to be equal to or lower than the control upper limit of the discharged-refrigerant temperature, so that the compressor 2 can be continuously operated without being substantially stopped.
  • the refrigerant thermal energy of the refrigerant excessively supplied to the evaporator 6 is recovered by the gas-liquid internal heat exchanger 4, the reduction in the refrigerating capacity can be suppressed to an extremely small level.
  • the compressor 2 can maintain the refrigerant gas suction, the liquid refrigerant is not sucked and the oil is not diluted, so that the lubricity of the compressor 2 is not affected.
  • the refrigerant flow rate can be finely controlled by using the expansion valve 5
  • the refrigerant flow rate can be controlled by using the minimum liquid return amount required to maintain the discharged-refrigerant temperature to be equal to or lower than the control upper limit of the discharged-refrigerant temperature, and thus stable operation is possible.
  • the discharged-refrigerant temperature protection control is stopped, and the opening degree of the expansion valve 5 is controlled by the evaporator outlet superheating degree control.
  • the discharged-refrigerant temperature protection control is ended and the control is shifted to the normal evaporator outlet superheating degree control, and the discharged-refrigerant temperature of the compressor 2 which has fallen too low by the discharged-refrigerant temperature protection control can be raised.
  • the discharged-refrigerant temperature protection control is stopped, and the opening degree of the expansion valve 5 is controlled to decrease by the evaporator outlet superheating degree control.
  • the discharged-refrigerant temperature protection control By the discharged-refrigerant temperature protection control, the discharged-refrigerant temperature of the compressor 2 is lowered and is below the lower limit of the value at which the refrigerant superheating degree at the outlet of the evaporator 6 is to be ensured, liquid back may occur in the compressor 2.
  • the opening degree of the expansion valve 5 is controlled to decrease, the refrigerant superheating degree at the outlet of the evaporator 6 can be increased. Further, the discharged-refrigerant temperature of the compressor 2 can be increased.
  • the discharged-refrigerant temperature of the compressor 2 is a value equal to or greater than the control lower limit d of the discharged-refrigerant temperature and equal to or lower than the control upper limit b of the discharged-refrigerant temperature
  • a control is performed such that the opening degree of the expansion valve 5 by the discharged-refrigerant temperature protection control is maintained.
  • the discharged-refrigerant temperature of the compressor 2 is controlled to be within the second predetermined range from the control lower limit d of the discharged-refrigerant temperature to the control upper limit b of the discharged-refrigerant temperature, so that there is little fluctuation in the discharged-refrigerant temperature, and stable operation can be continued.
  • the capacity of the chiller can be ensured and maintained.
  • the discharged-refrigerant temperature of the compressor 2 is determined after the predetermined time has elapsed and the refrigerant circuit of the chiller enters the steady state, and thus the determination can be correctly performed.
  • the control lower limit of the refrigerant superheating degree is a value smaller than the target refrigerant superheating degree in the evaporator outlet superheating degree control, the refrigerant superheating degree at the outlet of the evaporator 6 is ensured to a minimum, and it is possible to suppress the occurrence of the liquid back in the compressor 2.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Conditioning Control Device (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
EP19782212.5A 2018-04-05 2019-03-28 Dispositif de commande de congélateur, congélateur, procédé de commande de congélateur et programme de commande de congélateur Pending EP3760945A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018073193A JP7154800B2 (ja) 2018-04-05 2018-04-05 冷凍機の制御装置、冷凍機、冷凍機の制御方法および冷凍機の制御プログラム
PCT/JP2019/013853 WO2019194082A1 (fr) 2018-04-05 2019-03-28 Dispositif de commande de congélateur, congélateur, procédé de commande de congélateur et programme de commande de congélateur

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EP3760945A1 true EP3760945A1 (fr) 2021-01-06
EP3760945A4 EP3760945A4 (fr) 2021-05-19

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Publication number Priority date Publication date Assignee Title
JPS53163257U (fr) * 1971-06-04 1978-12-21
JPS58184454A (ja) * 1982-04-21 1983-10-27 株式会社日立製作所 冷媒制御装置
JPS6162770A (ja) * 1984-09-05 1986-03-31 株式会社日立製作所 冷凍空調装置の制御方法
JPH02233945A (ja) * 1989-03-03 1990-09-17 Daikin Ind Ltd 冷凍装置の運転制御装置
JP3253104B2 (ja) * 1991-06-03 2002-02-04 東芝キヤリア株式会社 冷凍サイクル装置
JP3327215B2 (ja) 1998-07-22 2002-09-24 三菱電機株式会社 空気調和機の冷媒充填量決定方法
JP4601392B2 (ja) 2004-10-29 2010-12-22 三洋電機株式会社 冷凍装置
JP5386141B2 (ja) 2008-10-23 2014-01-15 三菱重工業株式会社 ヒートポンプ装置の制御方法、ヒートポンプ装置の室外機およびヒートポンプ装置
JP6321363B2 (ja) * 2013-12-06 2018-05-09 シャープ株式会社 空気調和機
MY190716A (en) 2014-05-12 2022-05-12 Panasonic Ip Man Co Ltd Refrigeration cycle device
JP6229170B2 (ja) * 2015-05-20 2017-11-15 パナソニックＩｐマネジメント株式会社 冷凍サイクル装置

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WO2019194082A1 (fr) 2019-10-10
EP3760945A4 (fr) 2021-05-19
JP7154800B2 (ja) 2022-10-18

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