JP2009174803A - Central control system for freezing and refrigerating equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a central control system for freezing and refrigerating equipment wherein it is unnecessary to release a carbon dioxide refrigerant to the external of a secondary refrigerant circuit to resolve an excess pressure rise of the carbon dioxide refrigerant in a liquid receiver caused by a stop of a primary compressor. <P>SOLUTION: Cooling operations of a plurality of showcases 1A, 1B... are controlled in interlocking with a pressure value of the carbon dioxide refrigerant so that the pressure value of the carbon dioxide refrigerant detected by a pressure sensor 20 disposed in a liquid receiver 16 is kept within a range of a prescribed pressure value, in a case when the primary compressor 7 is stopped. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a primary side refrigerant circuit in which a primary side refrigerant discharged from a primary side compressor circulates through a primary side condenser, and a plurality of carbon dioxide refrigerants pressurized by a liquid pump from a liquid receiver. A refrigeration comprising a secondary refrigerant circuit that circulates through an evaporator built in each showcase, and a heat exchanger that exchanges heat between the primary refrigerant and the secondary carbon dioxide refrigerant. -Concerning a centralized management system for refrigeration equipment.

  Conventionally, a primary side refrigerant circuit, a secondary side refrigerant circuit through which carbon dioxide refrigerant circulates, and a heat exchanger are provided, and heat exchange is performed via the heat exchanger by the primary side refrigerant discharged from the common primary side compressor. In a refrigeration / refrigeration cycle in which the secondary carbon dioxide refrigerant is circulated and supplied to the evaporators built in a plurality of showcases, a centralized management system for refrigeration / refrigeration equipment that controls each device individually It is publicly known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-243290 (page 3, FIG. 2)

  However, in Patent Document 1, when the primary compressor stops, heat exchange between the two refrigerants by the heat exchanger tends to become unstable, and the pressure of the carbon dioxide refrigerant excessively rises to set pressure. It was difficult to keep below. Therefore, when the pressure of the carbon dioxide refrigerant rises excessively, the vaporized carbon dioxide refrigerant needs to be discharged out of the circuit in order to eliminate this, which has been a cause of CO2 emission.

  The present invention has been made paying attention to such problems, and in order to eliminate an excessive pressure increase of the carbon dioxide refrigerant in the liquid receiver caused by the stop of the primary side compressor, the carbon dioxide refrigerant is used. It aims at providing the centralized management system of the freezing / refrigeration equipment which does not need to discharge | release outside the secondary side refrigerant circuit.

In order to solve the above problems, a centralized management system for refrigeration / refrigeration equipment according to claim 1 of the present invention provides:
A primary side refrigerant circuit in which a primary side refrigerant discharged from a primary side compressor circulates through a primary side condenser, and a plurality of secondary side carbon dioxide refrigerants pressurized by a liquid pump from a liquid receiver. In a refrigeration / refrigeration cycle comprising a secondary refrigerant circuit that circulates through an evaporator built in each showcase, and a heat exchanger that exchanges heat between the primary refrigerant and carbon dioxide refrigerant ,
When the primary compressor stops, the pressure value of the carbon dioxide refrigerant detected by the pressure sensor provided in the receiver is linked to the pressure value so that it falls within a predetermined pressure value range. The cooling operation of the plurality of showcases is controlled.
According to this feature, in a refrigeration / refrigeration cycle including a primary side refrigerant circuit, a secondary side refrigerant circuit in which carbon dioxide refrigerant circulates, and a heat exchanger, the primary side compressor stops and heat When the heat exchange between the two refrigerants by the exchanger tends to become unstable, the pressure value of the carbon dioxide refrigerant in the receiver is linked to this pressure value so that a plurality of pressure values are within a predetermined pressure value range. By controlling the cooling operation of the showcase, in order to eliminate an excessive pressure increase of the carbon dioxide refrigerant in the receiver due to the stop of the primary side compressor, the carbon dioxide refrigerant is placed outside the secondary side refrigerant circuit. No need to release.

The centralized management system of the freezing / refrigeration equipment according to claim 2 of the present invention is the centralized management system of the freezing / refrigeration equipment according to claim 1,
The cooling operation of the showcase is suppressed or stopped when the pressure value of the carbon dioxide refrigerant detected by the pressure sensor exceeds a predetermined pressure value.
According to this feature, when the pressure value of the carbon dioxide refrigerant in the liquid receiver detected by the pressure sensor exceeds a predetermined pressure value, the secondary side refrigerant circuit is suppressed or stopped by suppressing the cooling operation of the showcase. Since the increase of the vaporized carbon dioxide refrigerant in the inside can be suppressed, the pressure of the liquid receiver can be lowered while suppressing energy consumption.

The centralized management system for refrigeration / refrigeration equipment according to claim 3 of the present invention is the centralized management system for refrigeration / refrigeration equipment according to claim 2,
The cooling operation of the showcase is stopped by stopping the electromagnetic pump that introduces carbon dioxide refrigerant into the liquid pump or the evaporator.
According to this feature, the solenoid valve that introduces the carbon dioxide refrigerant into the liquid pump or the evaporator is stopped, so that the carbon dioxide refrigerant is not circulated in the secondary refrigerant circuit, and this state is cooled in the showcase. By stopping the operation, it becomes easier to control the cooling operation of the showcase.

A centralized management system for refrigeration / refrigeration equipment according to claim 4 of the present invention is the centralized management system for refrigeration / refrigeration equipment according to any one of claims 1 to 3,
Carbon dioxide refrigerant in which the heat exchanger is always operated with a constant load setting, and the suction pressure of the primary compressor is converted into operation status information and primary refrigerant pressure for each showcase The capacity of the primary compressor is controlled by variably setting based on the pressure and the inherent pressure loss value.
According to this feature, in a refrigeration / refrigeration cycle comprising a primary refrigerant circuit, a secondary refrigerant circuit in which carbon dioxide refrigerant circulates, and a heat exchanger, the heat exchanger is always set at a constant load setting. Even during operation, the suction pressure of the primary side compressor is variably set based on the operating conditions, the carbon dioxide refrigerant pressure converted into the primary side refrigerant pressure, and the inherent pressure loss value for each showcase. By controlling the capacity of the primary compressor, the control method becomes simple and the refrigerant suction pressure is not set too low, so that the operating energy consumption of the refrigerator can be kept low. In particular, even if the primary side refrigerant and the secondary side carbon dioxide refrigerant are different refrigerants, the capacity control of the primary side compressor can be performed by converting various parameters in the secondary side refrigerant circuit into the primary side refrigerant. Can be performed accurately and easily.

  Examples of the present invention will be described below.

  Example 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a general structure of a freezing / refrigerating showcase, and FIG. 2 is a system diagram of a centralized management system for freezing / refrigerating equipment. FIG. 3 is a block diagram showing a schematic configuration of the control management unit, FIG. 4 is a table showing various types of information such as types and pressure loss values in units of showcases, and FIG. 5 is the same as FIG. FIG. 6 is a table showing a case where all showcases are in an operation stop state, and FIG. 6 is a diagram showing an eco-operation state when the suction pressure transition range of the primary compressor is automatically set.

  Reference numeral 1 in FIG. 1 is a refrigerated showcase configured as an open showcase installed in a supermarket or the like, and only one unit is shown in FIG. The showcases of the stands are connected to each other at intervals, and these showcases are controlled to be cooled by the refrigerator / refrigerator unit 3 of the same system.

As shown in FIGS. 1 and 2, the refrigerator / refrigerator unit 3 for freezing / refrigerating the showcase 1 includes a primary refrigerant circuit 4 in which chlorofluorocarbon as a primary refrigerant circulates and a secondary refrigerant. there carbon dioxide (hereinafter, CO ₂ abbreviated) is circulated a plurality of showcases 1A, the secondary side refrigerant circuit 5, respectively to cool the 1B · · ·, heat exchange for exchanging heat between the CFC and the CO ₂ And a so-called indirect cooling system that constitutes a refrigeration / refrigeration cycle. The refrigerator / refrigerator unit 3 is centrally managed by the control management unit 33 based on various data in the circuits 4 and 5, and the refrigerant capacity is controlled.

The primary refrigerant circuit 4 mainly includes a primary compressor 7, a condenser 8, a liquid receiver 9, and a liquid separator 14. Then, the refrigerant flon condensed and liquefied by the condenser 8 is supplied to the heat exchanger 6 through the liquid receiver 9 through the dryer 10 and the liquid amount adjustment valve 12, as shown by the arrow in FIG. The chlorofluorocarbon evaporates and cools the secondary side refrigerant CO ₂ in the heat exchanger 6, and then recovered by the primary side compressor 7 via the liquid separator 14. The chlorofluorocarbon heated and compressed in the primary compressor 7 is circulated and supplied to the condenser 8 to be condensed and liquefied again.

The secondary refrigerant circuit 5 includes a liquid receiver 16, a liquid pump 18, and a plurality of showcases 1A, 1B,..., Solenoid valves 11A, 11B,. .. and evaporators 15A, 15B... The refrigerant CO ₂ sent out from through pump 18 to the liquid receiver 16, as shown by the arrows in FIG. 2, it is supplied to the solenoid valve 11 and flow control valve 13 as the evaporator 15, where CO ₂ is The inside of the showcase 1 is cooled with the heat of vaporization, and then recovered in the liquid receiver 16. Further, the gas CO ₂ supplied from the liquid receiver 16 to the heat exchanger 6 is cooled and liquefied in the heat exchanger 6 and circulated to the liquid receiver 16 again.

  The liquid pump 18 in the secondary-side refrigerant circuit 5 is continuously operated at a constant load regardless of the operation state or the stop state of a plurality of showcases 1 to be described later, while in the primary-side refrigerant circuit 4 Since the primary side compressor 7 is operated while its suction pressure is variably set, heat exchange between the circuits 4 and 5 by the heat exchanger 6 is always performed during normal operation.

  Further, the display case 17 is provided with a plurality of product display shelves 17 in the main body of the showcase 1, and two passages, an inner cold air circulation passage 19 and an outer air circulation passage 21, are provided in the inner peripheral portion of the showcase 1. It is shaped into a heavy structure.

  As shown in FIG. 1, the air circulated in the showcase 1 by the blower 23 is cooled at the evaporator 15, becomes cold air, and enters the front opening of the showcase 1 via the inner cool air circulation passage 19. Guided to form a cold air curtain 25. On the other hand, the air circulated in the showcase 1 by the blower 23 passes through the air circulation passage 21 provided outside the cold air circulation passage 19 and forms a protective air curtain 28 outside the cold air curtain 25.

In the showcase 1, an internal temperature sensor 29 for measuring the internal temperature is installed, and a signal from the internal temperature sensor 29 is input to a controller (not shown). The controller compares the temperature measured by the internal temperature sensor 29 with the upper and lower limit values set in advance, and if the temperature is higher than the upper limit value, the solenoid valve 11 is opened and cooling is performed by introducing the refrigerant CO _2. Then, the solenoid valve 11 is closed to shut off the refrigerant CO ₂ to stop the cooling, and the inside temperature of the showcase 1 is controlled to be within the set temperature range.

Next, the centralized management system of the freezing / refrigeration equipment according to the present invention will be described with reference to FIG. In the secondary side refrigerant circuit 5 of the refrigerator / refrigerator unit 3, the secondary side refrigerant CO ₂ is circulated and supplied to the plurality of showcases 1A, 1B,. That is, the liquid receiver 16 branches to the solenoid valves 11A, 11B,... And the flow rate adjusting valves 13A, 13B,. The liquid CO ₂ supplied to the evaporators 15A, 15B,... Evaporates and cools the inside of each showcase 1A, 1B,... It is returned to the liquid receiver 16.

  As described above, the temperature control in each showcase 1A, 1B... Is based on the signals from the internal temperature sensors 29A, 29B. This is done by opening and closing the solenoid valves 11A, 11B,. The control management unit 33 receives operation status information and internal temperature information from the controllers 31A, 31B... Of each showcase 1A, 1B..., And the flow rate adjusting valves 13A, 13B. , 15B... The inlet temperature information of the evaporators 15A, 15B... Measured by the refrigerant temperature detection sensors 35A, 35B. An external signal E is output from the pressure sensor 37 to be measured to the control management unit 33, and the control management unit 33 is based on this information so that the optimum refrigerant suction pressure of the primary compressor 7 can be obtained. The control signal (i) is output to control the operation of the primary compressor 7 to centrally manage the refrigeration / refrigeration equipment.

The operating status information is used to determine whether or not the refrigerant CO ₂ is circulating in the evaporators 15A, 15B..., And the solenoid valves 11A, 11B. It is judged and outputted to the control management unit 33 as external signals A, C. Further, the inlet temperature information of the refrigerant CO ₂ measured by the temperature detection sensors 35A, 35B,... Is output to the control management unit 33 as external signals B, D,. , 1B... CO ₂ evaporation pressure (hereinafter simply referred to as CO ₂ pressure). Based on the CO ₂ pressure, the control management unit 33 converts the pressure into a CFC evaporation pressure in the primary refrigerant circuit 4 (hereinafter simply referred to as CFC pressure).

In this way, the inlet temperature of the secondary refrigerant CO ₂ introduced into the evaporators 15A, 15B,... Can be reflected in the capacity control of the primary compressor 7, and highly efficient capacity control. Is possible.

As in this embodiment, the inlet temperature information of the refrigerant CO ₂ measured by the temperature detection sensors 35A, 35B,... Is not limited to being converted into CO ₂ pressure in the control management unit 33. For example, the evaporator 15A , 15B... May be provided near the inlet or near the outlet, and the pressure of CO ₂ may be directly measured by the pressure sensor.

As shown in FIG. 3, the control management unit 33 includes a control unit 33a, an external signal input unit 33b, a control signal output unit 33c, a storage unit 33d, and a display unit 33e. Then, based on a predetermined conversion formula for converting the inlet temperature information into the CO ₂ pressure and a predetermined conversion formula for converting the CO ₂ pressure information into the chlorofluorocarbon pressure, which are stored in advance in the storage unit 33d, From the inlet temperature information thus obtained, the Freon pressure is uniquely converted through the CO ₂ pressure information. Next, on / off information (external signals A, C...) Of the associated solenoid valves 11A, 11B... From each controller 31A, 31B. , 1B... Receives the inlet temperature information (external signals B, D...) And the chlorofluorocarbon pressure information (external signal E) of each evaporator 15A, 15B. Information can be entered.

The controller 33a determines whether or not each showcase 1A, 1B,... Is in an operating state based on on / off information of the electromagnetic valves 11A, 11B,. The evaporation temperature of the refrigerant CO ₂ is converted from the inlet temperature information of each evaporator 15A, 15B,..., The CO ₂ pressure at that time is calculated, and further converted into a chlorofluorocarbon pressure. Stores and saves calculation results. In the storage unit 33d, various types of information can be stored in the external storage medium 33d 'such as a memory card and taken out, and various setting information stored in the external storage medium 33d' can be taken into the storage unit 33d.

  The display unit 33e is a signal conversion unit for displaying information when various setting information is input via the operation terminal or displaying various cooling information (such as the inside temperature) of the showcase. Alternatively, various kinds of cooling information can be displayed on an independent display panel (not shown). The control signal output unit 33c transmits a control signal A to the compressor control unit 39 in order to obtain the optimum refrigerant suction pressure of the primary side compressor 7 calculated by the control unit 33a based on various cooling information. In the compressor control unit 39, the rotational speed of the primary side compressor 7 is variably controlled by an inverter (not shown) so that the refrigerant suction pressure of the primary side compressor 7 becomes a value calculated by the control unit 33a.

In order to perform an efficient eco-operation in which energy consumption for driving the primary compressor 7 is suppressed as much as possible, an optimum value of the refrigerant suction pressure of the primary compressor 7 must be found. That is, since the power consumption of the primary side compressor 7 depends on the pressure difference obtained by subtracting the suction pressure from the discharge pressure of the primary side compressor 7, the pressure at which the refrigerant suction pressure of the primary side compressor 7 is high. Although it is desirable to operate with a value, in order to reliably circulate and supply the refrigerant CO ₂ to the evaporators 15A, 15B... Of each showcase 1A, 1B. It is necessary to obtain the CO ₂ pressure in units of the showcases 1A, 1B,... And the inherent pressure loss value possessed by each showcase 1A, 1B,. The specific pressure loss values referred to here are the CO ₂ flow resistance of the individual evaporators 15A, 15B,... Built in each showcase 1A, 1B,. Is obtained by converting the refrigerant pipe resistance from the position where the pressure sensor 37 is disposed to the pressure sensor 37 as a pressure loss value and is obtained by actual measurement for each showcase 1A, 1B... The information is stored in advance in the storage unit 33d.

  FIG. 4 shows the types of showcases and liquid pumps for each of a plurality of showcases including a showcase for fruits and vegetables that maintains the internal temperature at 2 to 15 ° C., and a showcase for fresh meat and fish that maintains −2 to 2 ° C. 18 shows the distance from 18 to the showcase, the pressure loss value, the refrigerant evaporating pressure in the showcase in the operating state at a certain point in time when the refrigerant suction pressure of the primary side compressor is sucked at 0.10 MPa. The showcase is installed 5 m away from the liquid pump 18 at the nearest point and 12 m or more away from the farthest one.

As shown in FIG. 4, for the showcase 1A, the CO ₂ pressure 2.19 MPa is calculated based on the inlet temperature information −15 ° C. of the refrigerant CO ₂ , and then based on the CO ₂ pressure 2.19 MPa. Then, the evaporation pressure (A) of the refrigerant flon is calculated to be 0.36 MPa. Then, a value obtained by subtracting the pressure loss value (R) 0.15 MPa inherent in the showcase 1A from the evaporation pressure (A) 0.36 MPa, that is, (A) − (R) = 0.36−0.15 = 0. If the suction pressure is lower than 21 MPa, the flow of the refrigerant stops due to the flow path resistance. Similarly, in the showcase 1B, it is necessary to suction at a suction pressure of (A) − (R) = 0.345−0.175 = 0.17 MPa or less. In order to circulate and supply the refrigerant to all the showcases operated in this way, 0.13 MPa of the showcase 1D where the value of (A)-(R) is the smallest value is used as a reference, and the suction of the compressor Although it is only necessary to operate at a pressure of 0.13 MPa or less, there is actually no problem because the refrigerant suction pressure of the primary compressor is operated at 0.10 MPa. However, in order to operate so that the refrigerant suction pressure of the primary side compressor becomes 0.10 MPa, it is necessary to constantly increase and decrease the rotation speed by inverter control of the primary side compressor. In general, the differential differential pressure is operated with a width of 0.03 MPa in the first embodiment.

  The value of the evaporation pressure (A) of each showcase shown in FIG. 4 is a value at a certain point in time. At the next moment, the solenoid valve that has been turned off is opened and the showcase enters an operating state. On the contrary, the showcase that has been in the driving state until now may enter the defrost state, and the value of (A)-(R) changes from moment to moment in units of each showcase. Accordingly, the smallest value of (A)-(R) constantly changes, and it is necessary to change the optimum refrigerant suction pressure setting range of the primary compressor 7 each time.

  Next, stop of the cooling operation of the plurality of showcases 1A, 1B... Or operation control of the primary compressor 7 based on the pressure of the carbon dioxide refrigerant in the liquid receiver 16 will be described.

As shown in FIG. 5, the control unit 33 a of the control management unit 33 is a pressure sensor provided in the liquid receiver 16 in the case of an emergency when the cooling operation of the plurality of showcases 1 </ b> A, 1 </ b> B. 20 (see FIG. 2), and the pressure value of the carbon dioxide refrigerant output as the external signal F is linked to this pressure value so that it falls within a predetermined pressure value range, that is, a plurality of showcases 1A, In conjunction with the state of the cooling operation of 1B..., The control for the idling operation of the primary compressor 7 is performed by a control signal a output to the compressor control unit 39. As described above, when the cooling operation of the plurality of showcases 1A, 1B,. In order to eliminate the excessive pressure rise of the carbon dioxide refrigerant in the liquid receiver 16 due to the stop of all the showcases 1A, 1B,..., The relief valve 22 provided in the liquid receiver 16 is opened. Thus, it is not necessary to release the carbon dioxide refrigerant to the outside of the secondary side refrigerant circuit 5, and the factor of CO ₂ emission can be avoided.

  Further, in this case, when the pressure value of the carbon dioxide refrigerant in the liquid receiver 16 is within a predetermined pressure value range, the primary side compressor 7 is controlled to perform an idling operation. By stopping the compressor 7, a load generated during re-operation can be avoided, and the primary side compressor 7 with low energy consumption can be operated.

  In addition, when all the cooling operations of the plurality of showcases 1A, 1B,... Are stopped, the control is not limited to the idling operation of the primary compressor 7. For example, in this case, the primary compressor 7 is used. May be performed, or control for causing the primary-side compressor 7 to be operated at a predetermined low load may be performed.

  Further, in the case of an emergency when the pressure value of the carbon dioxide refrigerant in the liquid receiver 16 exceeds a predetermined pressure value, the control unit 33a of the control management unit 33 performs control for forcibly operating the primary compressor 7. It is made to do. In this way, regardless of whether the primary-side compressor 7 is normally operated or stopped, the control is performed forcibly, and the heat exchange between the two refrigerants is actively performed, so that the carbon dioxide refrigerant excessively increases in pressure. The fear of doing can be eliminated.

  Next, the operation control of the showcase 1 based on the operation stop of the primary compressor 7 or the pressure of the carbon dioxide refrigerant in the liquid receiver 16 will be described.

When the primary compressor 7 is stopped, the control unit 33a of the control management unit 33 causes the pressure value of the carbon dioxide refrigerant detected by the pressure sensor 20 provided in the liquid receiver 16 to be within a predetermined pressure value range. The cooling operation of the plurality of showcases 1A, 1B,... Is controlled in conjunction with this pressure value, that is, in conjunction with the operating state of the primary side compressor 7, so as to be settled. Thus, when the primary compressor 7 stops and the heat exchange between the two refrigerants by the heat exchanger 6 is likely to become unstable, the pressure value of the carbon dioxide refrigerant in the liquid receiver 16 is a predetermined pressure value. By controlling the cooling operation of the plurality of showcases 1A, 1B... So as to fall within the range, excessive pressure rise of the carbon dioxide refrigerant in the liquid receiver 16 caused by the stop of the primary side compressor 7 Therefore, it is not necessary to open the relief valve 22 to release the carbon dioxide refrigerant to the outside of the secondary refrigerant circuit 5, thereby avoiding the cause of CO ₂ emission.

  Further, when the pressure value of the carbon dioxide refrigerant in the liquid receiver 16 exceeds the predetermined pressure value, the control unit 33a of the control management unit 33 sends a control signal to the liquid pump control unit 40 that controls the liquid pump 18. Are output to the electromagnetic valve control units 41A, 41B,... That control the electromagnetic valves 11A, 11B,..., And the liquid pump 18 or the electromagnetic valves 11A, 11B are output. ... By stopping the cooling operation of the showcases 1A, 1B... By doing in this way, since the increase of the vaporized carbon dioxide refrigerant in the secondary side refrigerant circuit 5 can be suppressed, the pressure of the liquid receiver 16 can be lowered while suppressing energy consumption. Further, the electromagnetic valves 11A, 11B... For introducing the carbon dioxide refrigerant into the liquid pump 18 or the evaporators 15A, 15B. The cooling operation of the showcases 1A, 1B,... Can be controlled easily by stopping the cooling operation of the showcases 1A, 1B,.

  When the pressure value of the carbon dioxide refrigerant in the liquid receiver 16 exceeds a predetermined pressure value, the control unit 33a of the control management unit 33 sets the operation of the liquid pump 18 to a predetermined low load operation or the electromagnetic valve 11A. , 11B... May be controlled to partially suppress the cooling operation of the showcases 1A, 1B.

  Stop the cooling operation of the plurality of showcases 1A, 1B... Described above, or control the operation of the primary compressor 7 based on the pressure of the carbon dioxide refrigerant in the liquid receiver 16, and stop the operation of the primary compressor 7. Alternatively, the operation control of the showcase 1 based on the pressure of the carbon dioxide refrigerant in the liquid receiver 16 may be performed so that the control unit 33a of the control management unit 33 can select any one of the operation controls. Moreover, you may perform both operation control repeatedly.

  FIG. 6 is a diagram showing the state of eco-operation of the centralized management system for refrigeration / refrigeration equipment according to the present invention, in which the optimum setting range of the refrigerant suction pressure of the primary compressor is automatically set. 6 represents a value (A)-(R) obtained by subtracting the pressure loss value (R) from the evaporation pressure value (A) of the showcase being operated by the control unit 33a of the control management unit 33. Is calculated for each required time, and the minimum value is plotted for each predetermined time. The load-up pressure PU (line segment Y) of the refrigerant suction pressure of the primary side compressor 7 is set lower than the line segment X by the pressure obtained by adding a pressure loss to the offset pressure of 0.04 MPa, so that the refrigeration capacity is afforded. I have it. As described above, the differential pressure difference between the load-up pressure PU and the load-down pressure PD (segment Z) is set to 0.03 MPa, so that the followability of the air volume control of the primary side compressor 7 is improved. At the same time, the capacity reversal operation (so-called hunting) of the primary compressor 7 in a short time is prevented, and the control characteristics are stabilized.

  The automatic setting of the optimum refrigerant suction pressure of the primary side compressor 7 will be described in detail. A line segment Y parallel to the line segment X, which is 0.04 MPa lower than the line segment X, which is an offset pressure, becomes a load-up line segment. A line segment that is 0.03 MPa lower than the line segment Y, which is a differential pressure difference, is a load-down line segment Z. Accordingly, the refrigerant suction pressure of the primary side compressor 7 is feedback-controlled so that the required time changes following the line segment X between the line segment Y and the line segment Z, for example, every minute.

  In the automatic adjustment method, the refrigerant suction pressure of the primary compressor 7 is measured for each set value by the pressure sensor 37, the measured value is taken into the external signal input unit 33b of the control management unit 33, and the measured value is measured by the control unit 33a. Is output from the control signal output unit 33c to the compressor control unit 39 so that is within the range of the load up pressure PU and the load down pressure PD. When the refrigerant suction pressure of the primary side compressor 7 is going to be higher than the load up pressure PU, the rotation speed of the primary side compressor 7 is increased by the inverter control to increase the output capacity, and conversely lower than the load down pressure PD. When trying to do so, control is performed to reduce the output capacity by lowering the rotational speed of the primary compressor 7. As a result, the refrigerant suction pressure of the primary side compressor 7 is always within the range of the load up pressure PU and the load down pressure PD.

  However, when the defrosts occur all at once and the solenoid valves of all the showcases are closed, the refrigerant stops flowing, and the refrigerant suction pressure of the primary side compressor 7 decreases not only within the range of the load up pressure PU and the load down pressure PD. Therefore, when a predetermined pressure lower than the load down pressure PD is reached, a stop command signal is issued from the control signal output unit 33c to the compressor control unit 39 to stop the operation of the primary compressor 7 and protect the refrigeration system. It is designed to be illustrated.

  As described above, the refrigerant suction pressure of the primary side compressor 7 is set every predetermined time with the lowest pressure value calculated from the calculated pressure values calculated every required time as a set pressure value, and this set pressure value is Since the setting is continuously changed according to the change of the operating condition over time, the highest suction pressure is selected in consideration of the flow resistance of the refrigerant and the control stability of the primary compressor 7. Energy consumption required for operation of the primary compressor 7 can always be kept low, cooling performance is improved, and energy-saving operation is realized compared to the conventional compressor drive control that has been set low with a margin for the set value it can.

As described above, in the refrigeration / refrigeration cycle including the primary refrigerant circuit 4, the secondary refrigerant circuit 5, and the heat exchanger 6, the heat exchanger 6 is always operated at a constant load setting. However, the suction pressure of the primary compressor 7 is changed to the operating state, the secondary refrigerant pressure converted into the primary refrigerant pressure, and the inherent pressure loss value for each showcase 1A, 1B,. Since the capacity of the primary side compressor 7 is controlled based on the variable setting, the control method becomes simple and the refrigerant suction pressure is not set too low, so that the operating energy consumption of the refrigerator is reduced. Can be suppressed. In particular, even if the primary side refrigerant (Freon) and the secondary side refrigerant (CO ₂ ) are different from each other as in the present embodiment, various parameters in the secondary side refrigerant circuit 5 are converted to the primary side refrigerant. Thus, the capacity control of the primary compressor 7 can be performed accurately and easily.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing an eco-operation state when the suction pressure transition range of the primary compressor is manually set.

  In this embodiment, a value (A)-(R) obtained by subtracting the pressure loss value (R) from the evaporation pressure value (A) of the operating showcase is calculated for each set value, and the minimum value is set as the required time. A period statistic is stored for each minute, and the value obtained by subtracting the offset pressure from the lowest value of each minimum value at the specified time as a reference is used as the load-up pressure, and the differential pressure difference is further calculated from that value. The subtracted value is used as the load down pressure, the load up pressure and the load down pressure range are fixed, and the suction pressure of the primary compressor 7 is changed within this range.

  As shown in FIG. 7, the lowest reference pressure is 0.17 MPa, the load up pressure is 0.13 MPa and the load down pressure is set to the differential differential pressure (0) in consideration of 0.04 MPa obtained by adding pressure loss to the offset pressure. .04 MPa), which is 0.09 MPa lower, and the minimum value of values (A)-(R) obtained by subtracting the pressure loss value (R) from the evaporation pressure value (A) of the showcase is plotted for each required time. Even if the line segment X indicates a high pressure, the suction pressure transition range of the primary-side compressor 7 remains unchanged. Therefore, compared with the first embodiment, the amount of energy consumption is slightly increased when the value of the line segment X is larger by the amount that the suction pressure transition range of the primary compressor 7 does not follow the line segment X. In addition, since the suction pressure as high as possible is manually selected in consideration of the control stability of the primary compressor 7, energy saving operation can be realized as compared with the conventional compressor drive.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the embodiment, the refrigerant evaporating pressure at that time is calculated from the refrigerant evaporating temperature information, but the refrigerant evaporating pressure may be directly detected by a sensor. In the embodiment, the pressure obtained by adding the pressure loss to the offset pressure is fixed at 0.03 MPa, and the differential differential pressure is fixed at 0.03 MPa or 0.04 MPa. The value can be appropriately changed according to the performance of the machine, the time of use, etc.

  In the embodiment, the refrigerant is supplied to 10 showcases in one system by a single refrigeration unit, and the operation of the primary compressor 7 is controlled by the control management unit. The number is not limited to 10 units. Also, a plurality of refrigerator units are prepared, a plurality of refrigerator units are provided for each group having a plurality of showcases, and these are managed and controlled by a control management unit. It is also possible. Further, the primary side compressor is not limited to the inverter type compressor, and any other type of compressor may be used as long as the suction pressure can be varied by capacity control.

  Further, in the examples, chlorofluorocarbon is shown as the primary refrigerant, but the material used as the primary refrigerant is not limited to this, and may be ammonia, isobutane, hydrocarbon, or the like.

It is general structure explanatory drawing of a freezing and refrigeration showcase. It is a systematic diagram of the centralized management system of freezing and refrigeration equipment. It is a block diagram which shows schematic structure of a control management unit. It is the table | surface which showed various information, such as a kind and a pressure loss value, in a showcase unit. FIG. 5 is a table showing a case where all the showcases are in an operation stop state as in FIG. 4. It is a diagram which shows the eco-operation condition at the time of automatically setting the suction pressure transition range of a primary side compressor. It is a diagram which shows the eco-operation condition at the time of setting manually the suction pressure transition range of a primary side compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Showcase 3 Refrigeration / refrigerator unit 4 Primary side refrigerant circuit 5 Secondary side refrigerant circuit 6 Heat exchanger 7 Primary side compressor 8 Condenser 11 Solenoid valve 15 Evaporator 16 Receiver 18 Liquid pump 20 Pressure sensor 33 Control management unit 35 Temperature detection sensor 37 Pressure sensor 39 Compressor control unit

Claims (4)

A primary side refrigerant circuit in which a primary side refrigerant discharged from a primary side compressor circulates through a primary side condenser, and a plurality of secondary side carbon dioxide refrigerants pressurized by a liquid pump from a liquid receiver. In a refrigeration / refrigeration cycle comprising a secondary refrigerant circuit that circulates through an evaporator built in each showcase, and a heat exchanger that exchanges heat between the primary refrigerant and carbon dioxide refrigerant ,
When the primary compressor stops, the pressure value of the carbon dioxide refrigerant detected by the pressure sensor provided in the receiver is linked to the pressure value so that it falls within a predetermined pressure value range. A centralized management system for refrigeration / refrigeration equipment, wherein the cooling operation of the plurality of showcases is controlled.   The refrigeration / refrigeration equipment according to claim 1, wherein when the pressure value of the carbon dioxide refrigerant detected by the pressure sensor exceeds a predetermined pressure value, the cooling operation of the showcase is suppressed or stopped. Centralized management system.   The freezing / refrigeration equipment according to claim 2, wherein the cooling operation of the showcase is stopped by stopping a solenoid valve for introducing a carbon dioxide refrigerant into the liquid pump or the evaporator. Centralized management system.   Carbon dioxide refrigerant in which the heat exchanger is always operated with a constant load setting, and the suction pressure of the primary compressor is converted into operation status information and primary refrigerant pressure for each showcase The centralized management of the refrigeration / refrigeration equipment according to any one of claims 1 to 3, wherein the capacity of the primary compressor is controlled variably by setting the pressure and the inherent pressure loss value. system.

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