JP2005293998A - Fuel cell power generation refrigeration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a fuel cell and prevent an increase in installation space and construction cost.
SOLUTION: A battery body 51 that receives power supply to generate electric power, an inverter 52 that converts output power from the battery body 51 into AC power, and a refrigerator 53 that uses an energy source other than electricity as a drive source. The intermediate part 54 of the connection line which connects the said inverter 52 and the auxiliary machine 56 of the refrigerator 53 is connected to the refrigerating air-conditioning power panel 4.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell power generation and refrigeration system in which output power from a fuel cell is used as operating power for a vapor compression refrigerator, and power from a commercial system is used as necessary.

2. Description of the Related Art Conventionally, it has been proposed to provide a storage battery or a fuel cell in order to supplementarily supply power to an inverter-driven air conditioner outdoor unit driven by power from a commercial system (see Patent Document 1).
JP 2001-201138 A

  Patent Document 1 describes only the auxiliary use of a fuel cell when there is a request for power saving for the purpose of power saving at an air-conditioning peak load. Also, there is no mention of efficient use throughout the year, such as when air conditioning is stopped or during an interim period. Therefore, the fuel cell cannot be effectively used.

In addition, a distributed power generation device has been conventionally proposed. For example, a power generation device is installed separately from an air conditioner. Therefore, a power board for connection to the generator and a power board for air conditioning are separately required in the power system, and installation space and construction costs increase.
The present invention has been made in view of the above problems, and provides a fuel cell power generation refrigeration system that can effectively use a fuel cell and can prevent or suppress an increase in installation space and construction cost. It is an object.

  A fuel cell power generation refrigeration system according to the present invention includes a refrigerator that uses an energy source other than electricity as a drive source for a refrigeration cycle, and a power generation unit configured by the fuel cell, and refrigerates part of the power generated by the fuel cell In addition to being supplied to the machine, the remainder of the power generated by the fuel cell is supplied to a general load through a power board common to the refrigerator.

  The refrigerator here is a refrigerator in a broad sense, and includes those that employ a refrigeration cycle such as a heat pump air conditioner.

  According to the present invention, by using a refrigerator that uses an energy source other than electricity as a drive source for the refrigeration cycle, the power generated by the fuel cell can be used effectively throughout the year, and the power generator power supply panel and air conditioning power panel Therefore, the installation space, equipment, and construction cost can be reduced, and a power generation refrigeration system excellent in economy and energy saving can be configured.

  In addition, in buildings where electric air conditioners are installed, if this power generation refrigeration system is introduced when the electric air conditioner is renewed, the existing air conditioning power panel can be used as it is as the power generator power panel. Cost can be greatly reduced.

  In this case, the power supply amount detecting means for detecting the power supply amount from the commercial system side to the in-building system connected to the fuel cell power generation / refrigeration system, and the fuel cell power generation / refrigeration system based on the detected power supply amount It is preferable to further include power output control means for performing power output control, the capacity control of the fuel cell can be appropriately performed, and reverse power flow to the commercial system side can be prevented.

  In addition, it is preferable to further include a power storage unit such as a secondary battery or a capacitor connected in parallel with the fuel cell. When the load fluctuation of the general load is fast and the operating capacity of the fuel cell does not follow, the power storage unit By charging and discharging, an imbalance between the load and the amount of power generated by the fuel cell can be absorbed.

  In addition, it is preferable to have multiple systems of fuel cell power generation refrigeration systems for one power consumer, which can closely follow the refrigeration and air conditioning load, and improve load followability by controlling the number of units even when the general load is small In addition, the reliability of power supply can be improved. In addition, if this system is introduced at the time of renewal of air conditioning equipment in a building where an electric air conditioner has been installed, the air conditioning power panel and power supply wiring of the electric air conditioner can be used as is. Cost increase can be reduced.

  Further, the power generation output system of the fuel cell is preferably connected to a commercial system through power wirings of a plurality of refrigerators, and even if fuel cells are centrally installed, the electrical wiring system is used as the wiring system of the refrigerator. In combination, when this system is introduced when renewing the air conditioning equipment in a building where an electric air conditioner was installed, the air conditioning power panel and power supply wiring of the electric air conditioner can be used as is. Increase in initial cost can be reduced. Also, if the fuel cell is a module configuration of a plurality of fuel cells, it can closely follow the refrigeration and air conditioning load, and even when the general load is small, the load followability can be improved by controlling the number of fuel cells, The reliability of power supply can be improved.

  In addition, it is preferable to further include a centralized controller that performs at least intensive operation control of the fuel cell with respect to the plurality of fuel cell power generation refrigeration systems, so that schedule operation, total power generation capacity control, and the like can be performed efficiently.

  In addition, the centralized controller preferably controls the operation of the fuel cell by inputting a detection signal of the amount of power supplied from the commercial power side to the in-building system connected with the fuel cell power generation refrigeration system. By concentrating information on the controller, appropriate centralized operation control can be performed.

Preferably, it further includes a charge output means for outputting at least a power charge and a fuel charge, and a control means for controlling the operation of the fuel cell and controlling the distribution of the output power in response to the charge, It is possible to perform detailed priority output control (control which output is prioritized) such as by season and by time, and the running merit can be maximized.
In addition, it is preferable that the fee output means can rewrite unit price data and fee calculation software for fee calculation from a remote location, save the customer from inputting these data and software, forget to update, etc. It is possible to prevent the disadvantages caused by.
In addition, the refrigerator that uses an energy source other than electricity as the driving source of the refrigeration cycle preferably uses a vapor compression type direct expansion cycle, and the direct expansion cycle refrigerator is provided for each load system. Distributing and disposing can facilitate the ability to follow the load and stop individual operations, and thus improve convenience and energy saving.

  The power generated by the fuel cell can be used effectively throughout the year, and since the power generator power panel and air conditioning power panel can be used together, the installation space, equipment, and construction costs can be reduced, and the economy and energy efficiency are excellent. In buildings where electric refrigeration systems can be configured and electric air conditioners are installed, if this power refrigeration system is introduced when the electric air conditioners are renewed, the existing air conditioning power panel can be used as is for the generator power supply. Since it can be used as a board, there is a specific effect that the introduction initial cost can be greatly reduced.

  Embodiments of a fuel cell power generation / refrigeration system according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an electric power system including an embodiment of a fuel cell power generation refrigeration system of the present invention.

  This power system is connected to a commercial system 1 with a general power load 3 via a general power panel 2 and a fuel cell power generation refrigeration system 5 via a refrigeration air conditioning power panel 4.

  The general power panel 2 and the refrigeration / air conditioning power panel 4 are well known in the art and will not be described.

  The general power load 3 is a load excluding a refrigerator and an air conditioner among power loads installed in a building, a store, and the like, and can be exemplified by an elevator, a light, a personal computer, and the like.

  The fuel cell power generation refrigeration system 5 includes a battery main body 51 that generates power by receiving a conventionally known fuel supply, an inverter 52 that converts output power from the battery main body 51 into AC power, and an energy source other than electricity. And a refrigerator 53 that uses as a drive source for the refrigeration cycle. In addition, the refrigerator 53 generates cold and warm heat in an air conditioner, for example. Further, a midway portion 54 of a connection line connecting the inverter 52 and the refrigerator 53 is connected to the refrigeration air conditioning power panel 4.

Since the refrigerator 53 uses an energy source other than electricity as a drive source for the refrigeration cycle, power consumption in the refrigerator 53 is auxiliary drive power, control power, and the like.
FIG. 2 is a diagram for explaining the power output to the general load 3 (see (A) in FIG. 2) and the power output to the refrigerator 53 (see (B) in FIG. 2).

As can be seen from FIG. 2, when the required power of the refrigerator 53 increases, the power output to the general load 3 decreases, and when the required power to the refrigerator 53 decreases, the power output to the general load 3 increases. Since the refrigerator uses an energy source other than electricity as a drive source for the refrigeration cycle, the required power is small only for the auxiliary power such as a fan, and most of the generated power can be supplied to the general load side.
Therefore, the power generated by the fuel cell can be used effectively throughout the year, and the power panel for the power generator and the power panel for air conditioning can be used together. Thus, a fuel cell power generation refrigeration system excellent in energy saving can be configured.

  In addition, in buildings where electric air conditioners are installed, if this power generation refrigeration system is introduced when the electric air conditioner is renewed, the existing air conditioning power panel can be used as it is as the power generator power panel. Cost can be greatly reduced.

  FIG. 3 is a block diagram showing another configuration of the power system including the fuel cell power generation / refrigeration system 5.

  In this power system, the general power load 3 is connected to the commercial system 1 via the general power panel 2, the fuel cell power generation refrigeration system 5 is connected to the commercial system 1 via the refrigeration air conditioning power panel 4, and the general power panel 2 The power amount detection unit 6 is connected between the refrigeration air conditioning power panel 4 and the commercial system 1, the power generation output detection unit 7 is connected between the refrigeration air conditioning power panel 4 and the inverter 52, and fuel is passed through the fuel processing device 55. Is supplied to the inverter 52, the output of the inverter 52 is supplied to the auxiliary machine 56 of the refrigerator 53, the output from the electric energy detector 6 and the output from the generator output detector 7 A control device 8 that outputs a control signal for the fuel processing device 55 and the inverter 52 using the output as an input is provided.

  The power amount detection unit 6 may actually detect a power amount, or may detect a current value as a value corresponding to the power amount.

  FIG. 4 is a flowchart for explaining the operation of the fuel cell power generation / refrigeration system 5 of FIG. 3. In step SP1, the current value IC flowing from the commercial system 1 side is detected, and in step SP2, the current value IC is the first value. It is determined whether or not the current value IC is smaller than the first threshold value ICL. In step SP3, it is determined whether or not the current value IC is smaller than the second threshold value ICH. To do.

  If the current value IC is smaller than the first threshold value ICL, the fuel cell power generation / refrigeration system power generation output control target value WS is set to 0 in step SP4.

When the current value IC is a value between the first threshold value ICL and the second threshold value ICH, in step SP5, the fuel cell power generation / refrigeration system power generation output control target value WS is set to WR × (IC−ICL) / Set to (ICH-ICL). Note that WR is a fuel cell rated output.
If the current value IC is equal to or greater than the second threshold value ICH, the fuel cell power generation / refrigeration system power generation output control target value WS is set to WR in step SP6.

  When the process of step SP4, the process of step SP5, or the process of step SP6 is performed, in step SP7, the fuel cell capacity is set so that the power generation output W is equal to the fuel cell power generation refrigeration system power generation output control target value WS. Control (for example, output control of the inverter 52 and fuel and air flow rate control in the fuel processing device 55) is performed.

  After the process of step SP7 is performed, the process of step SP1 is performed again.

The threshold used for control is
For example, the threshold value ICL is a current value corresponding to 30% of the fuel cell rated output,
The threshold value ICH is a current value corresponding to the fuel cell rated output,
It is determined as follows.

  In this way, as shown in FIG. 5, the fuel cell power generation refrigeration system power generation output control target value WS can be set according to the current value IC.

  In this case, the capacity control of the fuel cell can be appropriately performed, and a reverse power flow to the system power can be prevented.

FIG. 6 is a block diagram showing still another configuration of the fuel cell power generation / refrigeration system 5.
This fuel cell power generation / refrigeration system 5 differs from the fuel cell power generation / refrigeration system 5 of FIG. 3 only in that the power storage unit 58 is connected to the fuel cell main body 51 via a charge / discharge relay 57 controlled by the control device 8. .

  Examples of the power storage unit 58 include a secondary battery and a capacitor.

  In this case, when the load fluctuation of the general load is fast and the operating capacity of the fuel cell does not follow, the power storage unit 58 is charged and discharged, so that the power consumption of the load and the power generation amount of the fuel cell are reduced. Unbalance can be absorbed (see FIG. 7).

  FIG. 8 is a block diagram schematically showing an electric power system including an embodiment of the fuel cell power generation / refrigeration system of the present invention.

  This power system is connected to the commercial system 1 through a power amount detection unit 6 and a fuel cell power generation refrigeration system 5 through each of a plurality of refrigeration air conditioning power panels 4. Further, a general power load 3 is connected to the commercial system 1 via the power amount detection unit 6 and each of the plurality of general power panels 2. Then, the output from the electric energy detection unit 6 is supplied to one fuel cell power generation / refrigeration system 5 and necessary control data is sequentially supplied to the other fuel cell power generation / refrigeration system 5 through the communication wiring 9 for controlling a plurality of fuel cells. ing.

  However, FIG. 8 shows only the fuel cell main body 51 and the refrigerator 53, but it is a matter of course that other components described in the above embodiment are included.

  In this case, it is possible to closely follow the refrigeration and air conditioning load, and even when the general load is small, the load followability can be improved by controlling the number of units, and the reliability of power supply can be improved. In addition, if this system is introduced at the time of renewing the air conditioning equipment in a building where an electric air conditioner has been installed, the air conditioning power panel and power supply wiring of the electric air conditioner can be used as is. Cost increase can be reduced.

  FIG. 9 is a block diagram schematically showing an electric power system including an embodiment of the fuel cell power generation / refrigeration system of the present invention.

  This power system is different from the power system of FIG. 8 only in that the fuel cell main body 51 is divided into a plurality of power generation output systems and a refrigerator 53 is connected to each power generation output system.

  In this case, even if fuel cells are centrally installed, this system is introduced when the air conditioning equipment in a building where an electric air conditioner has been installed is installed by matching the electric wiring system with the wiring system of the refrigerator. In addition, the air conditioning power panel and power supply wiring of the electric air conditioner can be used as they are, and the increase in initial cost at the time of introduction can be reduced. Also, if the fuel cell is a module configuration of a plurality of fuel cells, it can closely follow the refrigeration and air conditioning load, and even when the general load is small, the load followability can be improved by controlling the number of fuel cells, The reliability of power supply can be improved.

  FIG. 10 is a block diagram schematically showing an electric power system including an embodiment of the fuel cell power generation / refrigeration system of the present invention.

In FIG. 10, a centralized controller 80 is provided, and an operating capacity command is supplied from the centralized controller 80 to each fuel cell power generation refrigeration system 5.
In this case, schedule operation (see, for example, FIG. 11), total power generation capacity control, and the like can be performed efficiently.

  FIG. 12 is a block diagram schematically showing an electric power system including an embodiment of the fuel cell power generation / refrigeration system of the present invention.

  In FIG. 12, this power system is connected to the commercial system 1 via the power amount detection unit 6 and further to each of the plurality of refrigeration air conditioning power panels 4 via the fuel cell power generation refrigeration system 5. . And the general electric power load 3 is connected with respect to the commercial system 1 via the electric energy detection part 6 and also via each of the some general power panel 2. FIG. Further, a centralized controller 80 is provided that performs predetermined processing using the output from the electric energy detection unit 6 as an input and supplies an operation command to the plurality of fuel cell power generation / refrigeration systems 5. The centralized controller 80 is connected to a remote monitoring computer 82 via a communication network 81 such as the Internet.

In this case, it is possible to perform appropriate operation control by concentrating information on the centralized controller 80. Further, the centralized controller 80 outputs at least a power rate and a fuel rate, It is preferable that a control unit that controls the operation of the fuel cell and the distribution of the output power is further included in response to the above, and detailed priority output control such as by season and by time (which output has priority) Control) and the running merit can be maximized.

  The fee output unit may calculate and output a fee, or may store a fee and output a necessary one.

  However, it is preferable that the charge output unit can rewrite the unit price data and the charge calculation software for calculating the charge from the remote monitoring computer 82, and the customer can save the trouble of inputting these data and software. It is possible to prevent disadvantages caused by forgetting.

  FIG. 13 is a flowchart for explaining an example of the power generation amount control process in the centralized controller 80.

  In step SP1, the target power generation output WSo is calculated based on the energy rate unit price. In step SP2, the current value IC flowing from the commercial system 1 side is detected. In step SP3, the current value IC is greater than the first threshold value ICL. If the current value IC is not smaller than the first threshold value ICL, it is determined in step SP4 whether the current value IC is smaller than the second threshold value ICH.

  If the current value IC is smaller than the first threshold value ICL, the fuel cell power generation output control target value WS is set to 0 in step SP5.

  When the current value IC is a value between the first threshold value ICL and the second threshold value ICH, in step SP6, the fuel cell power generation output control target value WS is set to WSo × (IC−ICL) / (ICH− ICL). Note that WR is a fuel cell rated output.

  If the current value IC is equal to or greater than the second threshold value ICH, in step SP7, the fuel cell power generation output control target value WS is set to WSo.

When the processing of step SP5, the processing of step SP6, or the processing of step SP7 is performed, in step SP8, the target power generation output WSi is calculated so that ΣWSi becomes WS (for example, WSi = WS / n The target power generation output WSi is calculated by calculation), and in step SP9, the target power generation output WSi is transmitted to each fuel cell power generation refrigeration system 5.
After the process of step SP9 is performed, the process of step SP1 is performed again.

The process in step SP1 is performed as follows, for example.
First, the electricity rate CE [yen / kWh] is calculated as follows.
In summer (7 / 1-9 / 30), weekdays from 13:00 to 16:00 CE = 15.9
In summer (7 / 1-9 / 30), weekdays 8 am-13:00, 16: 00-22: 00, CE = 14.7
Others (10/1-6/30), CE = 13.65 if weekdays are 8: 00-22: 00
From 22:00 to 8:00 or on holidays, CE = 6.05
Further, the calculation of the gas charge CG [yen / kWh] is performed as follows.
CG = 4
The maintenance cost CM [yen / kWh] is calculated as follows.
CM = 2
Further, the power generation efficiency E [−] is calculated.
E = 0.45
Based on these, the target power generation output WSo [kW] is calculated as follows.
If CG / E + CM <CE, WSo = WR
If CG / E + CM ≧ CE, WSo = 0
FIG. 14 is a flowchart for explaining processing of each fuel cell power generation / refrigeration system 5.
In step SP1, the target power generation output WSi is received from the centralized controller 80, and in step SP2, the capacity of the fuel cell is controlled so that the power generation output becomes the target power generation output WSi.

After the process of step SP2 is performed, the process of step SP1 is performed again.
In each of the above embodiments, the refrigerator is preferably one that uses a direct expansion cycle, and the direct expansion cycle refrigerator is distributed and arranged for each load system, so that load followability and individual operation are achieved. Stopping can be facilitated, and as a result, convenience and energy saving can be improved.

  FIG. 15 is a schematic block diagram showing still another embodiment of the fuel cell power generation / refrigeration system of the present invention.

  This fuel cell power generation refrigeration system 5 compresses refrigerant gas by a compressor 502 using a prime mover 501 such as a gas engine as a drive source, condenses it by a condenser 520, and decompresses it by an expansion valve 518, as conventionally known. The evaporator 519 has a refrigerant circuit for evaporating the refrigerant, and a four-way valve 507 for reversing the flow of the refrigerant is provided to perform a cooling operation or a heating operation.

  And the waste heat utilization heat exchanger 508 which performs heat exchange between the exhaust heat from the fuel cell main body 51 and the exhaust heat from the motor 501 and the refrigerant is provided.

  In this case, by using exhaust heat in the same system, it can be used appropriately, and as a result, energy saving can be improved.

  FIG. 16 is a schematic block diagram showing still another embodiment of the fuel cell power generation / refrigeration system of the present invention.

  The fuel cell power generation refrigeration system 5 supplies exhaust heat from the fuel cell main body 51 as a part of a heating heat source of an absorption cycle to an absorption chiller 509 that operates by receiving supply of fuel. Then, an aqueous solution of lithium bromide or the like output from the absorption chiller 509 is supplied to the heat exchanger 512 through the valve 511 by the pump 510 and returned to the absorption chiller 509 again.

  In addition, since the structure and effect | action of the absorption refrigerator 509 are conventionally well-known, description is abbreviate | omitted. However, it is also possible to adopt a conventionally known adsorption refrigerator that uses an adsorption cycle instead of the absorption refrigerator 509.

  In this case, the heat input amount of the heat driven refrigerator can be reduced.

  FIG. 17 is a schematic block diagram showing still another embodiment of the fuel cell power generation / refrigeration system of the present invention.

  This fuel cell power generation refrigeration system 5 exchanges heat between the exhaust heat from the fuel cell main body 51 and water instead of supplying the exhaust heat from the fuel cell main body 51 as a part of the heating heat source of the absorption cycle. The only difference from the fuel cell power generation refrigeration system of FIG. 16 is that a heat exchanger 513 for performing hot water supply is provided.

  However, the present invention is not limited to the one that supplies hot water, but can be applied to various devices that use heat.

  In this case, it is possible to enhance energy saving by preferentially using the exhaust heat for a device having low energy use efficiency as compared with the refrigerator.

It is a block diagram which shows the electric power grid | system containing one Embodiment of the fuel cell power generation refrigerating system of this invention. It is a figure explaining the electric power output to a general load, and the electric power output to a vapor compression refrigerator. It is a block diagram which shows the other structure of a fuel cell power generation refrigerating system. It is a flowchart explaining the effect | action of the fuel cell power generation refrigerating system of FIG. It is a figure explaining that the fuel cell electric power generation output control target value WS can be set according to electric current value IC. It is a block diagram which shows other structure of a fuel cell power generation refrigerating system. It is a figure which shows that the imbalance between the power consumption of load and the electric power generation amount of a fuel cell can be absorbed. 1 is a block diagram schematically showing an electric power system including an embodiment of a fuel cell power generation refrigeration system of the present invention. 1 is a block diagram schematically showing an electric power system including an embodiment of a fuel cell power generation refrigeration system of the present invention. 1 is a block diagram schematically showing an electric power system including an embodiment of a fuel cell power generation refrigeration system of the present invention. It is a figure which shows an example of the operating capacity command by time schedule driving | operation. 1 is a block diagram schematically showing an electric power system including an embodiment of a fuel cell power generation refrigeration system of the present invention. It is a flowchart explaining an example of the electric power generation amount control process of a centralized controller. It is a flowchart explaining an example of the electric power generation amount control process of a fuel cell power generation refrigerating system. It is a schematic block diagram which shows other embodiment of the fuel cell power generation refrigerating system of this invention. It is a schematic block diagram which shows other embodiment of the fuel cell power generation refrigerating system of this invention. It is a schematic block diagram which shows other embodiment of the fuel cell power generation refrigerating system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial system 4 Refrigeration air-conditioning power panel 5 Fuel cell power generation refrigerating system 6 Electric power detection part 7 Electric power generation output detection part 8 Control apparatus 51 Fuel cell main body 52 Inverter 53 Refrigerating machine 58 Power storage part 80 Centralized controller

Claims (10)

It has a refrigerator (53) using an energy source other than electricity as a drive source for the refrigeration cycle, and a power generation unit constituted by the fuel cell (51), and a part of the generated power of the fuel cell (51) is a refrigerator. (53), and the remainder of the generated power of the fuel cell (51) is supplied to the general load (3) through the power panel (4) shared with the refrigerator (53). system. Based on the detected power supply amount and the power supply amount detecting means (6) for detecting the power supply amount from the commercial system (1) side to the in-building system to which the fuel cell power generation refrigeration system (5) is connected. The fuel cell power generation refrigeration system according to claim 1, further comprising power output control means (8) for performing power output control of the fuel cell power generation refrigeration system (5). The fuel cell power generation refrigeration system according to claim 1 or 2, further comprising a power storage unit (58) connected in parallel with the fuel cell (51). The fuel cell power generation refrigeration system according to any one of claims 1 to 3, wherein a plurality of fuel cell power generation refrigeration systems (5) are provided for one electric power consumer. The fuel cell power generation / refrigeration system according to any one of claims 1 to 3, wherein a power generation output system of the fuel cell (51) is connected to a commercial system via power supply wires of a plurality of refrigerators (53). The fuel cell power generation refrigeration system according to claim 4 or 5, further comprising a centralized controller (80) that performs at least centralized operation control of the fuel cell (51) for the plurality of fuel cell power generation refrigeration systems (5). . The centralized controller (80) controls the operation of the fuel cell (51) with the detection signal of the amount of power supplied from the commercial power (1) side to the in-building system connected to the fuel cell power generation / refrigeration system (5) as an input. The fuel cell power generation refrigeration system according to claim 6. The charge output means for outputting at least the power charge and the fuel charge, and the control means for controlling the operation of the fuel cell and controlling the distribution of the output power in response to the charge. The fuel cell power generation refrigeration system according to any one of claims 7 to 9. 9. The fuel cell power generation refrigeration system according to claim 8, wherein the charge output means is capable of rewriting unit price data and charge calculation software for charge calculation from a remote location. The fuel cell power generation refrigeration system according to any one of claims 1 to 9, wherein the refrigerator (53) uses a direct expansion cycle.

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