JP2010032167A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily deal with a case of using various kinds of heat source fluid in a refrigerating device equipped with an evaporator for evaporating refrigerant by heatexchange with the heat source fluid. <P>SOLUTION: The air conditioner 1 includes a refrigerant circuit 12 composed by connecting a compressing mechanism 21, use side heat exchangers 32, 42, 52 which functions as radiators of the refrigerant, and a heat source side heat exchanger 23 which functions as the evaporator for evaporating the refrigerant by heat-exchange with the heat source fluid, a freezing prevention control means 97d for controlling to lower the maximum operation capacity of the compressing mechanism 21 when predetermined freezing prevention control conditions are satisfied, a freezing prevention determining means 97c for determining whether the freezing prevention control conditions are satisfied or not, a freezing prevention setting means 97a for setting information on the heat source fluid, and a freezing prevention changing means 97b for changing the freezing prevention control conditions according to the information on the heat source fluid set by the freezing prevention setting means 97a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus including an evaporator that evaporates a refrigerant by heat exchange with a heat source fluid.

Conventionally, there is a refrigeration apparatus provided with a refrigerant evaporator using water as a heat source. As such a refrigeration system, in order to prevent freezing of water in the evaporator, when the refrigerant pressure in the evaporator reaches near the saturation pressure of the refrigerant corresponding to the freezing temperature of water, the operating capacity of the compressor is reduced. There is one that performs control to lower (see Patent Document 1) and another that performs control to stop the compressor when the refrigerant temperature decreases at the outlet of the evaporator (see Patent Document 2).
JP-A-5-172441 JP-A-5-288437

  Further, depending on the installation environment of the refrigeration apparatus, a fluid other than water such as antifreeze (eg, an aqueous solution containing a component that changes the freezing temperature such as ethylene glycol or propylene glycol) is used as the heat source fluid of the evaporator. There are cases.

  However, in such a case, since a fluid other than water is used as the heat source fluid, a supplier of a refrigeration apparatus such as a manufacturer controls to prevent freezing of water in the evaporator. There is a problem that it is necessary to supply a refrigeration apparatus in which necessary settings and the like are set according to the heat source fluid to the user of the refrigeration apparatus, and a refrigeration apparatus that uses a fluid other than water as the heat source fluid cannot cope with it.

  An object of the present invention is to easily cope with a case where various heat source fluids are used in a refrigeration apparatus including an evaporator that evaporates a refrigerant by heat exchange with the heat source fluid.

  A refrigeration apparatus according to a first aspect of the present invention includes a compression mechanism that compresses a refrigerant, a radiator that radiates heat of the refrigerant compressed in the compression mechanism, and evaporation that evaporates the refrigerant radiated in the radiator by heat exchange with a heat source fluid. The refrigerant circuit comprised by connecting with a container is provided. The refrigeration apparatus further includes freeze prevention control means, freeze prevention determination means, freeze prevention setting means, and freeze prevention change means. The anti-freezing control means performs control to reduce the upper limit of the operating capacity of the compression mechanism when the predetermined anti-freezing control condition is reached and / or compression to prevent the heat source fluid from freezing in the evaporator. It is means for performing control to stop the mechanism. The freeze prevention determination means is a means for determining whether or not the freeze prevention control condition has been reached. The freeze prevention setting unit is a unit for setting information related to the heat source fluid. The anti-freezing changing means is means for changing the anti-freezing control condition in accordance with information on the heat source fluid set by the anti-freezing setting means.

  In this refrigeration apparatus, when the freeze prevention determination means determines that a predetermined freeze prevention control condition has been reached, the freeze prevention control means controls to lower the upper limit of the operating capacity of the compression mechanism, and / or Anti-freezing control used to determine whether or not to perform anti-freezing control, although it has a function to perform control to stop the compression mechanism (hereinafter, these controls are collectively referred to as “freezing prevention control”). Conditions should be changed depending on the heat source fluid used.

  Therefore, in this refrigeration apparatus, various anti-freezing fluids are provided by providing anti-freezing setting means for setting information relating to the heat source fluid, and changing the anti-freezing control conditions in accordance with the information relating to the heat source fluid. This makes it easy to handle when using

  This eliminates the need for costly measures such as supplying a refrigeration apparatus user with a refrigeration apparatus having anti-freezing control conditions set according to the conditions of the heat source fluid.

  The refrigeration apparatus according to a second aspect of the present invention is the refrigeration apparatus according to the first aspect of the present invention, wherein the antifreezing control means includes a first antifreezing control condition corresponding to control for reducing the upper limit of the operating capacity of the compression mechanism, and the compression mechanism. The second anti-freezing control condition for performing the control to stop the heat is such that the heat source fluid is more likely to freeze in the evaporator than the first anti-freezing control condition. is there.

  In this refrigeration apparatus, two anti-freezing control conditions are set: a first anti-freezing control condition corresponding to control for reducing the upper limit of the operating capacity of the compression mechanism, and a second anti-freezing control condition for performing control for stopping the compression mechanism. Since the second antifreeze control condition is set to a condition that the heat source fluid is more likely to freeze in the evaporator than the first antifreeze control condition, the upper limit of the operating capacity of the compression mechanism is reduced. Control is performed prior to control for stopping the compression mechanism.

  Thus, in this refrigeration apparatus, when there is a margin before the heat source fluid freezes in the evaporator, priority is given to continuation of operation by performing control to reduce the upper limit of the operation capacity of the compression mechanism, and the heat source fluid However, when an emergency state occurs, such as when the evaporator starts to freeze, it is possible to give priority to equipment protection of the evaporator and the compression mechanism by controlling the compression mechanism to stop.

  In the refrigeration apparatus according to the third invention, in the refrigeration apparatus according to the first or second invention, the antifreezing control condition is that the evaporation temperature of the refrigerant in the evaporator is equal to or lower than a predetermined lower limit evaporation temperature.

  A refrigeration apparatus according to a fourth aspect of the invention is the refrigeration apparatus according to the third aspect of the invention, wherein the evaporation temperature of the refrigerant in the evaporator is detected by a pressure sensor provided between the inlet of the evaporator and the suction side of the compression mechanism. It is obtained by converting the pressure of the obtained refrigerant.

  The refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to any one of the first to fourth aspects of the invention, wherein the antifreezing setting means uses the heat source fluid inlet temperature of the evaporator, the evaporator Information regarding at least one of the target outlet temperature of the heat source fluid, the circulation flow rate of the heat source fluid of the evaporator, and the concentration of each component when the heat source fluid is a mixed fluid of two or more components can be set The anti-freezing control condition includes the evaporator heat source fluid inlet temperature set by the anti-freezing setting means, the evaporator heat source fluid target outlet temperature, the evaporator heat source fluid circulation flow rate, and the heat source. When the fluid is a mixed fluid of two or more components, the fluid is changed based on at least one of the component concentrations.

  In this refrigeration apparatus, the inlet temperature of the heat source fluid of the evaporator, the target outlet temperature of the heat source fluid of the evaporator, the circulation flow rate of the heat source fluid of the evaporator, and when the heat source fluid is a mixed fluid of two or more components, Since the antifreeze control condition can be changed based on at least one of the component concentrations, the antifreeze control condition can be appropriately changed according to the heat source fluid to be used.

  As described above, according to the present invention, the following effects can be obtained.

  In the first, third and fourth inventions, anti-freezing setting means for setting information on the heat source fluid is provided, and the anti-freezing control condition is changed according to the information on the heat source fluid. Therefore, it is possible to easily cope with the use of various heat source fluids, so that a refrigeration apparatus in which freeze prevention control conditions are set according to the conditions of the heat source fluid is supplied to a user of the refrigeration apparatus at a high cost. No action is required.

  In the second aspect of the invention, when there is a margin before the heat source fluid freezes in the evaporator, priority is given to continuation of operation by reducing the upper limit of the operation capacity of the compression mechanism, and the heat source fluid evaporates. When the emergency state such as the start of freezing in the evaporator, it is possible to give priority to equipment protection of the evaporator and the compression mechanism by controlling the compression mechanism to stop.

  In the fifth aspect of the invention, the inlet temperature of the evaporator heat source fluid, the target outlet temperature of the evaporator heat source fluid, the circulation flow rate of the evaporator heat source fluid, and when the heat source fluid is a mixed fluid of two or more components Since the antifreezing control condition can be changed based on at least one of the concentrations of the components, the antifreezing control condition can be appropriately changed according to the heat source fluid to be used.

  Hereinafter, an embodiment of a refrigeration apparatus according to the present invention will be described based on the drawings.

(1) Basic Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an example of a refrigeration apparatus according to the present invention. The air conditioner 1 is a device used for indoor air conditioning such as a building by performing a vapor compression refrigeration cycle operation.

  The air conditioner 1 mainly includes one heat source unit 2, a plurality (three in this case) of usage units 3, 4 and 5, and connection units 6 connected to the usage units 3, 4 and 5, 7 and 8 and refrigerant communication pipes 9, 10, and 11 that connect the heat source unit 2 and the utilization units 3, 4, and 5 through connection units 6, 7, and 8. The cooling and heating operation can be performed in accordance with the requirements of the indoor air conditioning space where the use units 3, 4, and 5 are installed, such as performing the cooling operation while heating the other air-conditioned spaces. It is configured. That is, the vapor compression refrigerant circuit 12 of the air conditioner 1 includes a heat source unit 2, use units 3, 4, 5, connection units 6, 7, 8, and refrigerant communication pipes 9, 10, 11. It is configured by being connected.

<Usage unit>
The use units 3, 4, and 5 are installed by being embedded or suspended in an indoor ceiling of a building or the like, or are mounted on a wall surface of an indoor wall. The utilization units 3, 4, 5 are connected to the heat source unit 2 via the refrigerant communication pipes 9, 10, 11 and the connection units 6, 7, 8 and constitute a part of the refrigerant circuit 12.

  Next, the configuration of the usage units 3, 4, and 5 will be described. Since the usage unit 3 and the usage units 4 and 5 have the same configuration, only the configuration of the usage unit 3 will be described here, and for the configuration of the usage units 4 and 5, each part of the usage unit 3 will be described. The reference numbers 40 and 50 are used instead of the reference numbers 30 and the description of each part is omitted.

  The usage unit 3 mainly constitutes a part of the refrigerant circuit 12 and includes usage-side refrigerant circuits 12a (in the usage units 4 and 5, usage-side refrigerant circuits 12b and 12c, respectively). The use side refrigerant circuit 12 a mainly includes a use side expansion valve 31 and a use side heat exchanger 32. The utilization side expansion valve 31 is an electric expansion valve connected to one end of the utilization side heat exchanger 32 in order to adjust the flow rate of the refrigerant flowing in the utilization side refrigerant circuit 12a. The usage-side heat exchanger 32 is a heat exchanger that can function as a refrigerant evaporator and a refrigerant radiator, and is a fin-and-tube heat exchanger that exchanges heat between the refrigerant and indoor air. is there. The utilization unit 3 includes a blower fan (not shown) for supplying indoor air as supply air after inhaling indoor air into the unit and exchanging heat, and the indoor air and utilization side heat exchanger 32 are provided. It is possible to exchange heat with the refrigerant flowing through

  The utilization unit 3 is provided with various sensors. A first use side temperature sensor 33 that detects the temperature of the refrigerant is provided at one end side of the use side heat exchanger 32, and a second that detects the temperature of the refrigerant at the other end side of the use side heat exchanger 32. A use side temperature sensor 34 is provided. Furthermore, the utilization unit 3 is provided with an RA intake temperature sensor 35 for detecting the temperature of indoor air sucked into the unit. In addition, the usage unit 3 includes a usage-side control unit 36 that controls the operation of each unit constituting the usage unit 3. The use side control unit 36 includes a control board or the like on which a microcomputer or a memory provided for controlling the use unit 3 is mounted, and controls signals with a remote controller (not shown). It is possible to exchange control signals and the like with the heat source unit 2.

<Heat source unit>
The heat source unit 2 is installed on a rooftop of a building or the like, and is connected to the usage units 3, 4, 5 via the refrigerant communication pipes 9, 10, 11. A refrigerant circuit 12 is configured.

Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly constitutes a part of the refrigerant circuit 12 and includes a heat source side refrigerant circuit 12d. The heat source side refrigerant circuit 10d mainly includes a compression mechanism 21, a first switching mechanism 22, a heat source side heat exchanger 23,
A heat source side expansion valve 24, a receiver 25, a second switching mechanism 26, a first closing valve 27, a second closing valve 28, a third closing valve 29, a cooler 121, and a cooling circuit 122 are provided. ing.

  The compression mechanism 21 mainly includes a compressor 21a, an oil separator 21b connected to the discharge side of the compressor 21a, and a second oil return circuit 21d that connects the oil separator 21b and the suction pipe 21c of the compressor 21a. And have. The compressor 21a is a positive displacement compressor whose operating capacity can be varied by inverter control. The oil separator 21b is a container that separates refrigerating machine oil accompanying the high-pressure refrigerant compressed and discharged by the compressor 21a. The oil return circuit 21d is a circuit for returning the refrigeration oil separated in the oil separator 21b to the compressor 21a. The oil return circuit 21d mainly includes an oil return pipe 21e that connects the oil separator 21b and the suction pipe 21c of the compressor 21a, and a high-pressure refrigeration oil separated in the oil separator 21b that is connected to the oil return pipe 21e. And a capillary tube 21f for reducing the pressure. The capillary tube 21f is a thin tube that depressurizes the high-pressure refrigeration oil separated in the oil separator 21b to the refrigerant pressure on the suction side of the compressor 21a. Here, the compression mechanism 21 includes only one compressor 21a. However, the compression mechanism 21 is not limited to this, and two or more compressors are connected in parallel according to the number of units used. May be.

  When the first switching mechanism 22 causes the heat source side heat exchanger 23 to function as a radiator (hereinafter referred to as a heat radiation operation switching state), the discharge side of the compression mechanism 21 and one end side of the heat source side heat exchanger 23 are connected. When connecting and causing the heat source side heat exchanger 23 to function as an evaporator (hereinafter referred to as an evaporation operation switching state), the suction side of the compression mechanism 21 and one end side of the heat source side heat exchanger 23 are connected. The four-way switching valve is capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12d, the first port 22a is connected to the discharge side of the compression mechanism 21, and the second port 22b is a heat source. It is connected to one end side of the side heat exchanger 23, its third port 22 c is connected to the suction side of the compression mechanism 21, and its fourth port 22 d is connected to the suction side of the compression mechanism 21 via the capillary tube 91. It is connected. Then, as described above, the first switching mechanism 22 connects the first port 22a and the second port 22b, and connects the third port 22c and the fourth port 22d (corresponding to the heat radiation operation switching state, FIG. 1) (refer to the solid line of the first switching mechanism 22), the second port 22b and the third port 22c are connected, and the first port 22a and the fourth port 22d are connected (corresponding to the evaporation operation switching state, It is possible to perform switching to be performed (see the broken line of the first switching mechanism 22 in FIG. 1).

  The heat source side heat exchanger 23 is a heat exchanger that can function as a refrigerant evaporator and a refrigerant radiator, and is a plate heat exchanger that performs heat exchange between a heat source fluid such as water and antifreeze liquid and the refrigerant. is there. Here, various fluids are used as the heat source fluid depending on the installation environment of the air conditioner 1. For example, as the water, circulating water or river water supplied from a cooling tower facility or boiler facility is used, and as the antifreeze, an aqueous solution containing a component that changes the freezing temperature such as ethylene glycol or propylene glycol is used. used. One end side of the heat source side heat exchanger 23 is connected to the second port 22 b of the first switching mechanism 22, and the other end side is connected to the heat source side expansion valve 24. The heat source side heat exchanger 23 includes, for example, a plurality of flow paths extending in the vertical direction between the plate members by overlapping a plurality of plate members formed by pressing or the like via packing (not shown). It is formed, and the heat exchange can be performed by the refrigerant and the heat source fluid flowing alternately in the plurality of flow paths.

  The heat source side expansion valve 24 is an electric motor capable of adjusting the flow rate of the refrigerant flowing between the heat source side heat exchanger 23 and the use side refrigerant circuits 12a, 12b, and 12c via the first refrigerant communication pipe 9. It is an expansion valve and is connected to the other end side of the heat source side heat exchanger 23.

  The receiver 25 is a container for temporarily accumulating refrigerant flowing between the heat source side heat exchanger 23 and the use side refrigerant circuits 12a, 12b, and 12c. The receiver 25 is connected between the heat source side expansion valve 24 and the cooler 121.

  The second switching mechanism 26 is a case where the heat source unit 2 is used as a heat source unit for a cooling and heating simultaneous machine and when a high-pressure refrigerant is sent to the use-side refrigerant circuits 12a, 12b, 12c (hereinafter referred to as a heating load request operation state). In the case where the discharge side of the compression mechanism 21 and the second closing valve 28 are connected, and the heat source unit 2 is used as a heat source unit for a cooling / heating switching machine, This is a four-way switching valve capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12d so as to connect the closing valve 28 and the suction side of the compression mechanism 21, and the first port 26a thereof is the compression mechanism 21. The second port 26b is connected to the suction side of the compression mechanism 21 via the capillary tube 92, and the third port 26c is connected to the suction side of the compression mechanism 21. Ri, the fourth port 26d is connected to the second closing valve 28. As described above, the second switching mechanism 26 connects the first port 26a and the second port 26b, and connects the third port 26c and the fourth port 26d (corresponding to the cooling operation state during cooling / heating switching). 1) (refer to the solid line of the second switching mechanism 26 in FIG. 1), the second port 26b and the third port 26c are connected, and the first port 26a and the fourth port 26d are connected (heating load request operation state) Corresponding to (see the broken line of the second switching mechanism 26 in FIG. 1).

  The 1st closing valve 27, the 2nd closing valve 28, and the 3rd closing valve 29 are valves provided in the connection port with external apparatus and piping (specifically refrigerant communication piping 9, 10, and 11). . The first closing valve 27 is connected to the cooler 121. The second closing valve 28 is connected to the fourth port 26 d of the second switching mechanism 26. The third closing valve 29 is connected to the suction side of the compression mechanism 21.

  The cooler 121 radiates heat in the heat source side heat exchanger 23 and then depressurizes in the heat source side expansion valve 24 when the heat source side heat exchanger 23 functions as a heat sink when the heat source operation is switched, that is, the use side refrigerant. It is a heat exchanger that cools the refrigerant sent to the circuits 12a, 12b, and 12c. The cooler 121 is connected between the receiver 25 and the first closing valve 27. As the cooler 121, for example, a double-pipe heat exchanger can be used.

  The cooling circuit 122 is a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side refrigerant circuits 12a, 12b, and 12c when the heat radiation operation is switched, that is, when the heat source side heat exchanger 23 functions as a radiator. Is branched from the heat source side refrigerant circuit 12d and introduced into the cooler 121, and the refrigerant that is radiated in the heat source side heat exchanger 23, depressurized in the heat source side expansion valve 24, and sent to the use side refrigerant circuits 12a, 12b, and 12c. It is a circuit connected to the heat source side refrigerant circuit 12d so as to return to the suction side of the compression mechanism 21 after cooling. The cooling circuit 122 mainly includes an introduction pipe 122a for introducing a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side refrigerant circuits 12a, 12b, and 12c into the cooler 121, and a cooling connected to the introduction pipe 122a. It has a circuit side expansion valve 122b and a lead-out pipe 122c that returns the refrigerant that has passed through the cooler 121 to the suction side of the compression mechanism 21. One end of the introduction pipe 122 a is connected between the receiver 25 and the cooler 121. The other end of the introduction pipe 122a is connected to the inlet of the cooler 121 on the cooling circuit 122 side. The cooling circuit side expansion valve 122b is connected so that the cooling circuit 122 can be used as necessary, and is an electric expansion valve capable of adjusting the flow rate of the refrigerant flowing through the cooling circuit 122. One end of the outlet tube 122c is connected to the outlet of the cooler 121 on the cooling circuit 122 side. The other end of the outlet tube 122 c is connected to the suction side of the compression mechanism 21.

  The heat source unit 2 is provided with various sensors. Specifically, the heat source unit 2 includes a suction pressure sensor 93 that detects the suction pressure of the compression mechanism 21, a discharge pressure sensor 94 that detects the discharge pressure of the compression mechanism 21, and the discharge of refrigerant on the discharge side of the compression mechanism 21. A discharge temperature sensor 95 for detecting the temperature and a cooling circuit outlet temperature sensor 96 for detecting the temperature of the refrigerant flowing through the outlet pipe 122c of the cooling circuit 122 are provided. In addition, the heat source unit 2 includes a heat source side control unit 97 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 97 includes a control board or the like on which a microcomputer or a memory provided for controlling the heat source unit 2 is mounted. Control signals and the like can be exchanged with 36, 46, and 56.

<Connection unit>
The connection units 6, 7, 8 are installed together with the use units 3, 4, 5 inside a building or the like. The connection units 6, 7, 8 are interposed between the utilization units 3, 4, 5 and the heat source unit 2 together with the refrigerant communication pipes 9, 10, 11, and constitute a part of the refrigerant circuit 12. .

  Next, the configuration of the connection units 6, 7, and 8 will be described. Since the connection unit 6 and the connection units 7 and 8 have the same configuration, only the configuration of the connection unit 6 will be described here, and for the configuration of the connection units 7 and 8, each part of the connection unit 6 will be described. The reference numbers 70 and 80 are used instead of the reference numbers 60 and the description of each part is omitted.

  The connection unit 6 mainly constitutes a part of the refrigerant circuit 12 and includes a connection side refrigerant circuit 12e (in the connection units 7 and 8, connection side refrigerant circuits 12f and 12g, respectively). The connection-side refrigerant circuit 12e mainly includes a first connection pipe 61, a second connection pipe 62, a first on-off valve 66, and a second on-off valve 67. The first connection pipe 61 connects the first refrigerant communication pipe 9 and the use side expansion valve 31 of the use side refrigerant circuit 12a. The second connection pipe 62 includes a third connection pipe 63 connected to the second refrigerant communication pipe 10, a fourth connection pipe 64 connected to the third refrigerant communication pipe 11, and a third connection pipe 63 and a fourth connection. A joining connection pipe 65 that joins the pipe 64 is provided. The junction connecting pipe 65 is connected to the other end side of the use side heat exchanger 32 of the use side refrigerant circuit 12a. The first on-off valve 66 is an electromagnetic valve that is connected to the third connection pipe 63 and is capable of circulating and blocking the refrigerant. The second on-off valve 67 is an electromagnetic valve connected to the fourth connecting pipe 64 and capable of circulating and blocking the refrigerant. Thereby, the connection unit 6 is in a state where the first on-off valve 66 is closed and the second on-off valve 67 is opened when the use unit 3 performs the cooling operation (hereinafter referred to as the cooling operation switching state). Then, the refrigerant flowing into the first connection pipe 61 through the first refrigerant communication pipe 9 is sent to the use side expansion valve 31 of the use side refrigerant circuit 12a, and is reduced in pressure by the use side expansion valve 31 and evaporated in the use side heat exchanger 32. After that, it can function to return to the third refrigerant communication pipe 11 through the junction connecting pipe 65 and the fourth connecting pipe 64. The connection unit 6 closes the second on-off valve 67 and opens the first on-off valve 66 when the use unit 3 performs the heating operation (hereinafter referred to as the heating operation switching state). Then, the refrigerant flowing into the third connection pipe 63 and the junction connection pipe 65 through the second refrigerant communication pipe 10 is sent to the other end side of the use side heat exchanger 32 of the use side refrigerant circuit 12a. It can function to return to the first refrigerant communication pipe 9 through the first connection pipe 61 after radiating heat and being depressurized by the use side expansion valve 31. In addition, the connection unit 6 includes a connection side control unit 68 that controls the operation of each unit constituting the connection unit 6. The connection side control unit 68 includes a control board on which a microcomputer and a memory provided for controlling the connection unit 6 are mounted, and the connection side control unit 68 is connected to the use side control unit 36 of the use unit 3. It is possible to exchange control signals and the like.

  As described above, the use-side refrigerant circuits 12a, 12b, and 12c, the heat source-side refrigerant circuit 12d, the refrigerant communication pipes 9, 10, and 11, and the connection-side refrigerant circuits 12e, 12f, and 12g are connected, and air conditioning. A refrigerant circuit 12 of the device 1 is configured. That is, the refrigerant circuit 12 includes the compression mechanism 21, the heat source side heat exchanger 23, the use side heat exchangers 32, 42, 52, the heat source side heat exchanger 23, and the use side heat exchangers 32, 42, 52. The first refrigerant communication pipe 9, the heat source side expansion valve 24, and the heat source side heat exchanger 23 functioning as a radiator for the refrigerant discharged from the compression mechanism 21 and the heat source side heat exchanger. The first switching mechanism 22 that enables switching between the evaporative operation switching state that causes the refrigerant to function as a refrigerant evaporator, and is connected between the discharge side of the compression mechanism 21 and the first switching mechanism 22. Cooling operation switching in which the second refrigerant communication pipe 10 capable of branching the discharged refrigerant before flowing into the first switching mechanism 22 and the use side heat exchangers 32, 42, 52 function as a refrigerant evaporator. Condition and use side heat exchanger 32, Connection units 6, 7, and 8 (specifically, on-off valves 66, 76, and 86 and on-off valves 67, 77, and 87) that enable switching between a heating operation switching state in which 2, 52 functions as a refrigerant radiator. And a third refrigerant communication pipe 11 for sending the refrigerant evaporated in the use side heat exchangers 32, 42, 52 to the suction side of the compression mechanism 21, and the heat source side heat exchanger 23 and the use side heat exchanger 32. , 42 and 52 can be switched to function individually as a refrigerant evaporator or radiator. Thereby, in the air conditioning apparatus 1, for example, it is possible to perform a so-called cooling and heating simultaneous operation in which the use units 3 and 4 perform a cooling operation while the use unit 5 performs a heating operation.

(2) Basic operation of the air conditioner Next, the basic operation of the air conditioner 1 will be described.

  The operation mode of the air conditioner 1 includes a heating operation mode in which all of the usage units 3, 4, and 5 perform a heating operation according to the air conditioning load of each usage unit 3, 4, and 5, and usage units 3, 4, 5 Can be divided into a cooling operation mode in which all of them perform a cooling operation, and a cooling and heating simultaneous operation mode in which some of the usage units 3, 4, and 5 perform a cooling operation while another usage unit performs a heating operation. In the cooling / heating simultaneous operation mode, when the heat source side heat exchanger 23 of the heat source unit 2 is operated as an evaporator due to the air conditioning load of the entire utilization units 3, 4, and 5 (evaporation operation switching state). In addition, the operation mode can be divided into the case where the heat source side heat exchanger 23 of the heat source unit 2 is operated as a radiator (operation of switching heat dissipation operation).

  Hereinafter, basic operations in the four operation modes of the air conditioner 1 will be described.

<Heating operation mode>
When all the usage units 3, 4, and 5 are operated for heating, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 2 (the refrigerant flow is attached to the refrigerant circuit 12 of FIG. 2). (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the evaporation operation switching state (the state indicated by the broken line of the first switching mechanism 22 in FIG. 2), and the second switching is performed. By switching the mechanism 26 to the heating load request operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 2), the heat source side heat exchanger 23 functions as an evaporator and the second refrigerant communication pipe 10 The high-pressure refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization units 3, 4, and 5. Moreover, the opening degree of the heat source side expansion valve 24 is adjusted so as to depressurize the refrigerant. In addition, the cooling circuit side expansion valve 122b of the cooling circuit 122 is closed, and the supply of the cooling heat source to the cooler 121 is cut off so that the refrigerant flowing between the receiver 25 and the utilization units 3, 4, and 5 is not cooled. It is in a state. In the connection units 6, 7, and 8, the on-off valves 67, 77, and 87 are closed and the on-off valves 66, 76, and 86 are opened, so that the use-side heat exchangers 32, 42, It is in the state (namely, heating operation switching state) which functions 52 as a heat radiator. In the usage units 3, 4, and 5, the usage-side expansion valves 31, 41, 51 are, for example, the refrigerant temperature detected by the first usage-side temperature sensors 33, 43, 53 and the second usage-side temperature sensors 34, 44. The opening degree is adjusted according to the heating load of each utilization unit, for example, the opening degree is adjusted based on the refrigerant temperature detected at 54.

  In such a configuration of the refrigerant circuit 12, the high-pressure refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated in the oil separator 21b from most of the refrigerating machine oil accompanying the high-pressure refrigerant. It is sent to the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the oil return circuit 21d. The high-pressure refrigerant sent to the second switching mechanism 26 is sent to the second refrigerant communication pipe 10 through the first port 26 a and the fourth port 26 d of the second switching mechanism 26 and the second closing valve 28. The high-pressure refrigerant sent to the second refrigerant communication pipe 10 is branched into three and sent to the third connection pipes 63, 73, 83 of the connection units 6, 7, 8. The high-pressure refrigerant sent to the third connection pipes 63, 73, 83 of the connection units 6, 7, 8 passes through the on-off valves 66, 76, 86 and the merging connection pipes 65, 75, 85 to use units 3, 4, 5 to the use side heat exchangers 32, 42, 52. The high-pressure refrigerant sent to the use side heat exchangers 32, 42, 52 exchanges heat with indoor air in the use side heat exchangers 32, 42, 52 of the use units 3, 4, 5. Dissipate heat. On the other hand, indoor air is heated and supplied indoors. The refrigerant that has dissipated heat in the use side heat exchangers 32, 42, 52 passes through the use side expansion valves 31, 41, 51 and is then sent to the first connection pipes 61, 71, 81 of the connection units 6, 7, 8. . Then, the refrigerant sent to the first connection pipes 61, 71, 81 is sent to the first refrigerant communication pipe 9 and merges. Then, the refrigerant sent to the first refrigerant communication pipe 9 and merged is sent to the receiver 25 through the first closing valve 27 and the cooler 121 of the heat source unit 2. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then decompressed by the heat source side expansion valve 24. Then, the refrigerant decompressed by the heat source side expansion valve 24 evaporates by exchanging heat with the heat source fluid in the heat source side heat exchanger 23 to become a low pressure refrigerant, and is sent to the first switching mechanism 22. Then, the low-pressure refrigerant sent to the first switching mechanism 22 is returned to the suction side of the compression mechanism 21 through the second port 22b and the third port 22c of the first switching mechanism 22. In this way, the basic operation in the heating operation mode is performed.

<Cooling operation mode>
When all the usage units 3, 4, and 5 are in cooling operation, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 3 (the refrigerant flow is attached to the refrigerant circuit 12 of FIG. 3). (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, by switching the first switching mechanism 22 to the heat radiation operation switching state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 3), The side heat exchanger 23 is made to function as a radiator. The heat source side expansion valve 24 is in an opened state. In the connection units 6, 7, 8, the use side heat exchangers 32, 42, of the use units 3, 4, 5 are opened by closing the open / close valves 66, 76, 86 and opening the open / close valves 67, 77, 87. 52 functions as an evaporator, and the use side heat exchangers 32, 42, 52 of the use units 3, 4, 5 are connected to the suction side of the compression mechanism 21 of the heat source unit 2 via the third refrigerant communication pipe 11. (Ie, a cooling operation switching state). In the usage units 3, 4, and 5, the usage-side expansion valves 31, 41, 51 are, for example, the refrigerant temperature detected by the first usage-side temperature sensors 33, 43, 53 and the second usage-side temperature sensors 34, 44. The opening degree is adjusted according to the cooling load of each utilization unit, for example, the opening degree is adjusted based on the refrigerant temperature detected at 54.

  In such a configuration of the refrigerant circuit 12, the high-pressure refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated in the oil separator 21b from most of the refrigerating machine oil accompanying the high-pressure refrigerant. It is sent to the first switching mechanism 22. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the oil return circuit 21d. The high-pressure refrigerant sent to the first switching mechanism 22 is sent to the heat source side heat exchanger 23 through the first port 22 a and the second port 22 b of the first switching mechanism 22. The high-pressure refrigerant sent to the heat source side heat exchanger 23 dissipates heat by exchanging heat with the heat source fluid in the heat source side heat exchanger 23. The refrigerant radiated in the heat source side heat exchanger 23 is sent to the receiver 25 after passing through the heat source side expansion valve 24. Then, after the refrigerant sent to the receiver 25 is temporarily stored in the receiver 25, a part of the refrigerant is branched to the cooling circuit 122 and decompressed by the cooling circuit side expansion valve 122 b, and the rest is supplied to the cooler 121. Sent. The refrigerant sent to the cooler 121 is cooled by exchanging heat with the refrigerant branched into the cooling circuit 122 and decompressed by the cooling circuit side expansion valve 122b. Then, the refrigerant cooled in the cooler 121 is sent to the first refrigerant communication pipe 9 through the first closing valve 27. The refrigerant flowing through the cooling circuit 122 is returned to the suction side of the compression mechanism 21 after heat exchange in the cooler 121. Here, the cooling circuit side expansion valve 122b is opened based on, for example, the degree of superheat of the cooler 121 (calculated from the refrigerant temperature detected by the cooling circuit outlet temperature sensor 96 provided in the outlet pipe 122c of the cooling circuit 122). The degree is adjusted. Then, the refrigerant sent to the first refrigerant communication pipe 9 is branched into three and sent to the first connection pipes 61, 71, 81 of the connection units 6, 7, 8. The refrigerant sent to the first connection pipes 61, 71, 81 of the connection units 6, 7, 8 is sent to the use side expansion valves 31, 41, 51 of the use units 3, 4, 5. The refrigerant sent to the use side expansion valves 31, 41, 51 is decompressed by the use side expansion valves 31, 41, 51, and then exchanges heat with indoor air in the use side heat exchangers 32, 42, 52. To evaporate into a low-pressure refrigerant. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure refrigerant is sent to the merging connection pipes 65, 75, 85 of the connection units 6, 7, 8. The low-pressure refrigerant sent to the junction connection pipes 65, 75, 85 is sent to the third refrigerant communication pipe 11 through the on-off valves 67, 77, 87 and the fourth connection pipes 64, 74, 84 and merges. . Then, the low-pressure refrigerant sent to the third refrigerant communication pipe 11 and joined together is returned to the suction side of the compression mechanism 21 through the third closing valve 29. In this way, the basic operation in the cooling operation mode is performed.

<Cooling and heating simultaneous operation mode (evaporation load)>
Of the usage units 3, 4, 5, for example, the cooling operation of the usage unit 3, and the heating operation of the usage units 4, 5 are performed simultaneously. Accordingly, the basic operation when the heat source side heat exchanger 23 of the heat source unit 2 is operated with functioning as an evaporator (evaporation operation switching state) will be described. At this time, the refrigerant circuit 12 of the air-conditioning apparatus 1 is configured as shown in FIG. 4 (see the arrows attached to the refrigerant circuit 12 in FIG. 4 for the flow of the refrigerant). Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the evaporation operation switching state (indicated by the broken line of the first switching mechanism 22 in FIG. 4), as in the heating operation mode described above. The heat source side heat exchanger 23 functions as an evaporator by switching the second switching mechanism 26 to the heating load required operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 4). In addition, the high-pressure refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization units 4 and 5 through the second refrigerant communication pipe 10. Moreover, the opening degree of the heat source side expansion valve 24 is adjusted so as to depressurize the refrigerant. In addition, the cooling circuit side expansion valve 122b of the cooling circuit 122 is closed, and the supply of the cooling heat source to the cooler 121 is cut off so that the refrigerant flowing between the receiver 25 and the utilization units 3, 4, and 5 is not cooled. It is in a state. In the connection unit 6, by closing the first on-off valve 66 and opening the second on-off valve 67, the usage-side heat exchanger 32 of the usage unit 3 functions as an evaporator, and the usage-side heat of the usage unit 3 is used. The exchanger 32 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via the third refrigerant communication pipe 11 (that is, the cooling operation switching state). In the usage unit 3, the usage-side expansion valve 31 adjusts the opening degree based on the refrigerant temperature detected by the first usage-side temperature sensor 33 and the refrigerant temperature detected by the second usage-side temperature sensor 34, for example. The opening degree is adjusted according to the cooling load of the use unit 3. In the connection units 7 and 8, the use side heat exchangers 42 and 52 of the use units 4 and 5 function as a radiator by closing the second on-off valves 77 and 87 and opening the first on-off valves 76 and 86. It is in the state to be made (that is, the heating operation switching state). In the usage units 4 and 5, the usage-side expansion valves 41 and 51 include, for example, the refrigerant temperature detected by the first usage-side temperature sensors 43 and 53 and the refrigerant temperature detected by the second usage-side temperature sensors 44 and 54. The opening degree is adjusted in accordance with the heating load of each of the usage units 4 and 5.

  In such a configuration of the refrigerant circuit 12, the high-pressure refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated in the oil separator 21b from most of the refrigerating machine oil accompanying the high-pressure refrigerant. It is sent to the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the oil return circuit 21d. The high-pressure refrigerant sent to the second switching mechanism 26 is sent to the second refrigerant communication pipe 10 through the first port 26 a and the fourth port 26 d of the second switching mechanism 26 and the second closing valve 28. The high-pressure refrigerant sent to the second refrigerant communication pipe 10 is branched into two and sent to the third connection pipes 73 and 83 of the connection units 7 and 8. The high-pressure refrigerant sent to the third connection pipes 73 and 83 of the connection units 7 and 8 passes through the first on-off valves 76 and 86 and the junction connection pipes 75 and 85, and the use-side heat exchangers 42 of the use units 4 and 5. 52. The high-pressure refrigerant sent to the usage-side heat exchangers 42 and 52 radiates heat by exchanging heat with indoor air in the usage-side heat exchangers 42 and 52 of the usage units 4 and 5. On the other hand, indoor air is heated and supplied indoors. The refrigerant that has dissipated heat in the use side heat exchangers 42 and 52 passes through the use side expansion valves 41 and 51, and then is sent to the first connection pipes 71 and 81 of the connection units 7 and 8. Then, the refrigerant sent to the first connection pipes 71 and 81 is sent to the first refrigerant communication pipe 9 and merges. A part of the refrigerant sent to and merged with the first refrigerant communication pipe 9 is sent to the first connection pipe 61 of the connection unit 6. Then, the refrigerant sent to the first connection pipe 61 of the connection unit 6 is sent to the use side expansion valve 31 of the use unit 3. The refrigerant sent to the use-side expansion valve 31 is decompressed by the use-side expansion valve 31 and then evaporated by exchanging heat with indoor air in the use-side heat exchanger 32 to become a low-pressure refrigerant. . On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure refrigerant is sent to the merging connection pipe 65 of the connection unit 6. Then, the low-pressure refrigerant sent to the junction connection pipe 65 is sent to the third refrigerant communication pipe 11 through the second on-off valve 67 and the fourth connection pipe 64 and merges. Then, the low-pressure refrigerant sent to the third refrigerant communication pipe 11 is returned to the suction side of the compression mechanism 21 through the third closing valve 29. On the other hand, the remaining refrigerant excluding the refrigerant sent from the first refrigerant communication pipe 9 to the connection unit 6 and the utilization unit 3 is sent to the receiver 25 through the first closing valve 27 and the cooler 121 of the heat source unit 2. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then decompressed by the heat source side expansion valve 24. Then, the refrigerant decompressed by the heat source side expansion valve 24 evaporates by exchanging heat with the heat source fluid in the heat source side heat exchanger 23 to become a low pressure refrigerant, and is sent to the first switching mechanism 22. Then, the low-pressure refrigerant sent to the first switching mechanism 22 is returned to the suction side of the compression mechanism 21 through the second port 22b and the third port 22c of the first switching mechanism 22. In this way, the basic operation in the cooling / heating simultaneous operation mode (evaporation load) is performed.

<Cooling and heating simultaneous operation mode (heat radiation load)>
Of the usage units 3, 4, 5, for example, the usage units 3, 4 are in a cooling operation and the usage unit 5 is in a heating / cooling simultaneous operation mode. Accordingly, the basic operation when the heat source side heat exchanger 23 of the heat source unit 2 is operated by functioning as a radiator (radiation operation switching state) will be described. At this time, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 5 (refer to the arrows attached to the refrigerant circuit 12 in FIG. 5 for the flow of the refrigerant). Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the heat radiation operation switching state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 5), and the second switching is performed. By switching the mechanism 26 to the heating load request operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 5), the heat source side heat exchanger 23 functions as a radiator and the second refrigerant communication pipe 10 The high-pressure refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization unit 5 through the unit. The heat source side expansion valve 24 is in an opened state. In the connection units 6 and 7, the use side heat exchangers 32 and 42 of the use units 3 and 4 function as an evaporator by closing the first on-off valves 66 and 76 and opening the second on-off valves 67 and 77. In addition, the use side heat exchangers 32 and 42 of the use units 3 and 4 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via the third refrigerant communication pipe 11 (that is, the cooling operation switching state). )It has become. In the usage units 3 and 4, the usage-side expansion valves 31 and 41 include, for example, the refrigerant temperature detected by the first usage-side temperature sensors 33 and 43 and the refrigerant temperature detected by the first usage-side temperature sensors 34 and 44. The degree of opening is adjusted according to the cooling load of each of the usage units 3 and 4, such as adjusting the degree of opening based on. In the connection unit 8, the use side heat exchanger 52 of the use unit 5 functions as a radiator by closing the second on-off valve 87 and opening the first on-off valve 86. In the usage unit 5, the usage-side expansion valve 51 adjusts the opening degree based on the refrigerant temperature detected by the first usage-side temperature sensor 53 and the refrigerant temperature detected by the second usage-side temperature sensor 54, for example. The opening degree is adjusted according to the heating load of the use unit 5.

  In such a configuration of the refrigerant circuit 12, the high-pressure refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated in the oil separator 21b from most of the refrigerating machine oil accompanying the high-pressure refrigerant. It is sent to the first switching mechanism 22 and the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the oil return circuit 21d. Of the high-pressure refrigerant compressed and discharged by the compression mechanism 21, the high-pressure refrigerant sent to the first switching mechanism 22 passes through the first port 22 a and the second port 22 b of the first switching mechanism 22 and heat source side heat It is sent to the exchanger 23. The high-pressure refrigerant sent to the heat source side heat exchanger 23 dissipates heat by exchanging heat with the heat source fluid in the heat source side heat exchanger 23. The refrigerant radiated in the heat source side heat exchanger 23 passes through the heat source side expansion valve 24, and then the high pressure refrigerant compressed and discharged by the compression mechanism 21 through the pressurizing circuit 111 joins (details will be described later). To the receiver 25. Then, after the refrigerant sent to the receiver 25 is temporarily stored in the receiver 25, a part of the refrigerant is branched to the cooling circuit 122 and decompressed by the cooling circuit side expansion valve 122 b, and the rest is supplied to the cooler 121. Sent. The refrigerant sent to the cooler 121 is cooled by exchanging heat with the refrigerant branched into the cooling circuit 122 and decompressed by the cooling circuit side expansion valve 122b. Then, the refrigerant cooled in the cooler 121 is sent to the first refrigerant communication pipe 9 through the first closing valve 27. The refrigerant flowing through the cooling circuit 122 is returned to the suction side of the compression mechanism 21 after heat exchange in the cooler 121. Here, the cooling circuit side expansion valve 122b is opened based on, for example, the degree of superheat of the cooler 121 (calculated from the refrigerant temperature detected by the cooling circuit outlet temperature sensor 96 provided in the outlet pipe 122c of the cooling circuit 122). The degree is adjusted. On the other hand, among the high-pressure refrigerant compressed and discharged by the compression mechanism 21, the high-pressure refrigerant sent to the second switching mechanism 26 is connected to the first port 26a and the fourth port 26d of the second switching mechanism 26, and the second closure. It is sent to the second refrigerant communication pipe 10 through the valve 28. Then, the high-pressure refrigerant sent to the second refrigerant communication pipe 10 is sent to the third connection pipe 83 of the connection unit 8. The high-pressure refrigerant sent to the third connection pipe 83 of the connection unit 8 is sent to the use side heat exchanger 52 of the use unit 5 through the first on-off valve 86 and the junction connection pipe 85. The high-pressure refrigerant sent to the use side heat exchanger 52 dissipates heat by exchanging heat with indoor air in the use side heat exchanger 52 of the use unit 5. On the other hand, indoor air is heated and supplied indoors. The refrigerant that has dissipated heat in the usage-side heat exchanger 52 passes through the usage-side expansion valve 51 and is then sent to the first connection pipe 81 of the connection unit 8. Then, the refrigerant sent to the first connection pipe 81 is sent to the first refrigerant communication pipe 9, and the first switching mechanism 22, the heat source side heat exchanger 23, the heat source side expansion valve 24, the receiver 25, and the cooler 121. And the refrigerant sent to the first refrigerant communication pipe 9 through the first closing valve 27 is joined. The refrigerant flowing through the first refrigerant communication pipe 9 is branched into two and sent to the first connection pipes 61 and 71 of the connection units 6 and 7. Then, the refrigerant sent to the first connection pipes 61 and 71 of the connection units 6 and 7 is sent to the use side expansion valves 31 and 41 of the use units 3 and 4. The refrigerant sent to the use side expansion valves 31 and 41 is depressurized by the use side expansion valves 31 and 41 and then evaporated by exchanging heat with indoor air in the use side heat exchangers 32 and 42. And low pressure refrigerant. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure refrigerant is sent to the junction connection pipes 65 and 75 of the connection units 6 and 7. The low-pressure refrigerant sent to the junction connection pipes 65 and 75 is sent to the third refrigerant communication pipe 11 through the second on-off valves 67 and 77 and the fourth connection pipes 64 and 74 and merges. Then, the low-pressure refrigerant sent to the third refrigerant communication pipe 11 is returned to the suction side of the compression mechanism 21 through the third closing valve 29. In this way, the basic operation in the cooling / heating simultaneous operation mode (heat radiation load) is performed.

(3) Freezing prevention control according to the first embodiment However, in the air conditioning apparatus 1 described above, in the heat source side heat exchanger 23 that functions as a refrigerant evaporator in the heating operation mode or the simultaneous heating and cooling operation mode (heat radiation load). If the heat source fluid freezes, the refrigerant flowing into the heat source side heat exchanger 23 will not evaporate, so that it flows into the compression mechanism 21 (more specifically, the compressor 21a) with the liquid refrigerant mixed. As a result, liquid compression occurs, which may damage the compressor 21a. Therefore, in the present embodiment, when the heat source fluid is in an urgent state such as starting to freeze in the heat source side heat exchanger 23, the heat source side heat exchanger 23 and the compression mechanism 21 are protected for equipment. In addition, anti-freezing control for stopping the compressor 21a is performed. Hereinafter, the freeze prevention control according to the present embodiment will be described with reference to FIGS. 1, 2, 4, 6, and 7. Here, FIG. 6 is a control block diagram of the freeze prevention control of the present embodiment, and FIG. 7 is a flowchart of the freeze prevention control of the present embodiment.

  In the air conditioner 1, the heat source side control unit 97 of the heat source unit 2 is provided with a freeze prevention setting unit 97a for setting information on the heat source fluid. Here, as the freeze prevention setting means 97a, a dip switch of the heat source side control unit 97 provided for performing various control settings of the air conditioner 1 is used. For example, in this embodiment, assuming that a mixed fluid of two components of water and ethylene glycol is used as a heat source fluid, the component concentration (here, the concentration of ethylene glycol) is set in the freeze prevention setting unit 97a. Can be set. The anti-freezing setting means 97a is not limited to the dip switch, and any means can be used as long as it can set information on the heat source fluid.

  And after installation of the air conditioner 1, when information (here, component concentration) regarding the heat source fluid is set in the freeze prevention setting means 97a of the heat source side control unit 97 (see step S1), the heat source side control unit 97 The freeze prevention changing unit 97b changes the freeze prevention control condition initially set in the heat source side control unit 97 according to the set information on the heat source fluid (see step S2). Here, the freeze prevention control condition is that the evaporation temperature Te of the refrigerant in the heat source side heat exchanger 23 functioning as an evaporator is equal to or lower than a predetermined lower limit evaporation temperature TeL1, and at the initial setting, water is used as the heat source fluid. Is set to the value of the lower limit evaporation temperature TeL1 corresponding to the freezing temperature (0 ° C.) when the concentration of ethylene glycol is 0 wt%, for example, 30 wt% ethylene glycol as the heat source fluid. When using an aqueous solution of the above, the initially set lower limit evaporation temperature TeL1 is lower than the lower limit evaporation temperature TeL1 corresponding to the freezing temperature (about −10 ° C.) than when water is used as the heat source fluid. Will be changed to a lower value). The lower limit evaporating temperature TeL1 as the antifreezing control condition is calculated by the antifreezing changing unit 97b according to the information on the heat source fluid set by the antifreezing setting unit 97a, or the lower limit evaporating temperature TeL1 prepared in advance. Selected from.

  Then, after the freeze prevention control condition is changed by the freeze prevention changing means 97b, the air conditioner 1 is operated in the heating operation mode or the simultaneous heating / cooling operation mode (heat radiation load) as described above. At this time, if the refrigerant evaporating temperature Te in the heat source side heat exchanger 23 functioning as an evaporator becomes equal to or lower than the lower limit evaporating temperature TeL1 as the antifreezing control condition for some reason, the antifreezing determining means 97c of the heat source side control unit 97 is used. Determines that the air-conditioning apparatus 1 has reached the freeze prevention control condition (see step S3). Here, the evaporating temperature Te is a refrigerant detected by a pressure sensor (here, the suction pressure sensor 93) provided between the inlet of the heat source side heat exchanger 23 as an evaporator and the suction side of the compression mechanism 21. Is obtained by converting the pressure (here, the suction pressure of the compression mechanism 21) into its saturation temperature, and the freeze prevention judging means 97c is obtained by the evaporation temperature Te and the lower limit evaporation temperature TeL1 thus obtained. Is compared to determine whether or not the air conditioner 1 has reached the freeze prevention control condition.

  When the freeze prevention determination unit 97c determines that the air-conditioning apparatus 1 has reached the freeze prevention control condition, the freeze prevention control unit 97d of the heat source side control unit 97 includes the compression mechanism 21 (here, The compressor 21a) is controlled to be stopped, and the heat source fluid freezing in the heat source side heat exchanger 23 as an evaporator and the compression mechanism 21 (here, the compressor 21a) are prevented from being compressed, thereby the evaporator The heat source side heat exchanger 23 and the compression mechanism 21 (here, the compressor 21a) are protected. In this way, the freeze prevention control according to the present embodiment is performed.

  In the air conditioner 1 having antifreezing control according to the present embodiment as described above, when it is determined by the antifreezing determination means 97c that the predetermined antifreezing control condition (here, the lower limit evaporation temperature TeL1) has been reached. In addition, the anti-freezing control means 97d has a function of performing anti-freezing control for stopping the compression mechanism 21, but the anti-freezing control condition used for determining whether or not to perform the anti-freezing control is used. It should be changed according to the heat source fluid.

  Therefore, in the air conditioner 1, as described above, the antifreezing setting means 97a for setting information on the heat source fluid is provided, and the antifreezing control condition is changed in accordance with the information on the heat source fluid. Thus, it is possible to easily cope with the use of various heat source fluids.

  This eliminates the need for high-cost measures such as supplying an air conditioner to the user of the air conditioner in which antifreezing control conditions are set according to the conditions of the heat source fluid.

(4) Freezing prevention control according to the second embodiment In the freezing prevention control according to the first embodiment, in order to protect the equipment of the heat source side heat exchanger 23 and the compression mechanism 21 as an evaporator, the freezing prevention determination means 97c. Thus, when it is determined that a predetermined anti-freezing control condition (here, the lower limit evaporation temperature TeL) has been reached, the anti-freezing control for stopping the compression mechanism 21 is performed by the anti-freezing control means 97d. . However, if such anti-freezing control is employed, the frequency of stopping the compression mechanism 21 may increase in the heating operation mode or the simultaneous cooling / heating operation mode (heat radiation load), which is not preferable from the viewpoint of continuing the operation. In some cases.

  Therefore, in the freeze prevention control according to the present embodiment, as shown in FIG. 8, when the freeze prevention determination unit 97c determines that the air-conditioning apparatus 1 has reached the freeze prevention control condition (see step S13). ), The freeze prevention control means 97d of the heat source side control unit 97 performs control to reduce the upper limit of the operating capacity of the compression mechanism 21 (here, the compressor 21a) (see step S14), and the heat source side heat exchanger The flow rate of the refrigerant does not increase too much compared to the flow rate of the heat source fluid flowing through the heat source fluid 23, and the freezing of the heat source fluid in the heat source side heat exchanger 23 as an evaporator and the compression mechanism 21 (here, the compressor 21a) The operation of the air conditioner 1 is continued while preventing liquid compression. Here, also in the present embodiment, the freeze prevention control condition is that the refrigerant evaporation temperature Te in the heat source side heat exchanger 23 functioning as an evaporator is equal to or lower than the lower limit evaporation temperature TeL2 as in the first embodiment. However, unlike the first embodiment, the antifreezing control according to the present embodiment gradually lowers the upper limit of the operating capacity of the compression mechanism 21, so that the heat source fluid evaporates the lower limit evaporation temperature TeL2. It is preferable to set a value with a little margin (that is, a value higher than the lower limit evaporation temperature TeL1 in the first embodiment) before freezing in the heat source side heat exchanger 23 as a heat exchanger. In the present embodiment, control for reducing the upper limit of the operating capacity of the compression mechanism 21 is performed by inverter control of the compressor 21a. Note that the control configuration (see FIG. 6) and steps S1 and S2 in the present embodiment are the same as steps S1 and S2 in the first embodiment, and thus description thereof is omitted here.

  In the air conditioning apparatus 1 having antifreezing control according to this embodiment as well, as in the first embodiment, the air conditioning apparatus in which the antifreezing control conditions are set according to the conditions of the heat source fluid is used as the user of the air conditioning apparatus. High-cost measures such as supplying to the printer become unnecessary.

(5) Anti-freezing control according to the third embodiment In the first embodiment, the anti-freezing control for stopping the compression mechanism 21 when the anti-freezing control condition is reached is performed, and in the second embodiment, the anti-freezing control condition. In this case, the control for lowering the upper limit of the operating capacity of the compression mechanism 21 is performed. However, as shown in FIG. 9, both the antifreezing control according to the first and second embodiments are performed. You may do it.

  That is, in this embodiment, in steps S1 to S4 of the first embodiment, the freeze prevention control condition in step S3 is set as the second freeze prevention control condition, and it is determined in step S3 that the second freeze prevention control condition is reached. When this is done, as in the first embodiment, control is performed to stop the compression mechanism 21 (here, the compressor 21a) in step S4, and in step S3, the second antifreezing control condition is not reached. When it is determined, the process proceeds to step S13. In step S13, it is determined whether or not the first anti-freezing control condition is reached, and when it is determined that the second anti-freezing control condition is reached. Performs control to lower the upper limit of the operating capacity of the compression mechanism 21 (here, the compressor 21a), and when it is determined that the second anti-freezing control condition has not been reached. Compression mechanism 21 (here, the compressor 21a) without control to reduce the upper limit of the operating capacity of the one in which the process returns to step S3. Here, as for the second freeze prevention control condition, as in the first embodiment, the refrigerant evaporation temperature Te in the heat source side heat exchanger 23 functioning as an evaporator is set to be equal to or lower than the lower limit evaporation temperature TeL1, As for the antifreezing control condition, as in the second embodiment, the lower limit evaporating temperature TeL2 is a value with a little margin before the heat source fluid freezes in the heat source side heat exchanger 23 as an evaporator (that is, the antifreezing control condition). In other words, the second antifreezing control condition is frozen in the heat source side heat exchanger 23 as an evaporator as compared with the first antifreezing control condition. Is set to a condition that is likely to occur. Note that the control configuration (see FIG. 6) and steps S1 and S2 in the present embodiment are the same as steps S1 and S2 in the first embodiment, and thus description thereof is omitted here.

  In the air conditioning apparatus 1 having the antifreezing control according to the present embodiment, the first antifreezing control condition corresponding to the control for reducing the upper limit of the operating capacity of the compression mechanism 21 and the control for stopping the compression mechanism 21 are performed. Two anti-freezing control conditions are set as a second anti-freezing control condition to be performed, and the second anti-freezing control condition is a heat source side heat exchanger in which the heat source fluid is an evaporator as compared with the first anti-freezing control condition. Therefore, the control for reducing the upper limit of the operating capacity of the compression mechanism 21 is performed prior to the control for stopping the compression mechanism 21. Thereby, in this embodiment, when there is some margin before the heat source fluid freezes in the heat source side heat exchanger 23 as an evaporator, by performing control to reduce the upper limit of the operating capacity of the compression mechanism 21 Prioritizing the continuation of operation, the evaporator is controlled by stopping the compression mechanism 21 when the heat source fluid is in an urgent state such as starting to freeze in the heat source side heat exchanger 23 as an evaporator. It is possible to prioritize equipment protection of the heat source side heat exchanger 23 and the compression mechanism 21 (here, the compressor 21a).

(6) Other Embodiments While the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments and can be changed without departing from the scope of the invention. It is.

<A>
In the above-described embodiment, assuming that water or an ethylene glycol aqueous solution is used as the heat source fluid of the heat source side heat exchanger 23, at the initial setting, the freezing temperature (0 when the ethylene glycol concentration is 0 wt%) The lower limit evaporation temperature TeL1 and / or TeL2 as freeze prevention control conditions corresponding to (° C.) is set, and the component concentration (here, ethylene glycol concentration) as information on the heat source fluid is set as the freeze prevention setting means 97a. In this case, the value of the lower limit evaporation temperature TeL1 and / or TeL2 is changed by the freeze prevention changing means 97b. However, when the heat source fluid is a mixed fluid of three or more components, The concentration is set by the freeze prevention setting means 97a, and the lower limit evaporation temperature TeL1 and / or the freeze prevention change means 97b. It may be configured to change the value of TeL2.

  Further, instead of the component concentration or together with the component concentration, the information regarding the other heat source fluid is set by the freeze prevention setting unit 97a, and the lower limit evaporation temperature TeL1 and / or TeL2 is set by the freeze prevention changing unit 97b. The value of may be changed. For example, as information on the heat source fluid, the inlet temperature of the heat source fluid of the heat source side heat exchanger 23 as an evaporator, the target outlet temperature of the heat source fluid of the heat source side heat exchanger 23 as an evaporator, the heat source side heat as an evaporator The circulation flow rate of the heat source fluid of the exchanger 23 and, when the heat source fluid is a mixed fluid of two or more components, at least one of the component concentrations can be set by the freeze prevention setting means 97a, and the freeze prevention changing means. In 97b, the first and / or second anti-freezing control conditions may be changed based on at least one of these pieces of information set by the anti-freezing setting means 97a. Thereby, the 1st and / or 2nd freezing prevention control conditions can be changed appropriately according to the heat source fluid used.

<B>
In the above-described embodiment, the example in which the present invention is applied to the air conditioner 1 capable of simultaneous cooling and heating operation has been described. However, the present invention is not limited thereto. The present invention may be applied to an air conditioner.

  By using the present invention, a refrigeration apparatus including an evaporator that evaporates a refrigerant by heat exchange with a heat source fluid can easily cope with the use of various heat source fluids.

It is a schematic block diagram of the air conditioning apparatus as an example of the freezing apparatus concerning this invention. It is a schematic block diagram explaining the operation | movement in the heating operation mode of an air conditioning apparatus. It is a schematic block diagram explaining the operation | movement in the air_conditionaing | cooling operation mode of an air conditioning apparatus. It is a schematic block diagram explaining the operation | movement in the heating / cooling simultaneous operation mode (evaporation load) of an air conditioning apparatus. It is a schematic block diagram explaining the operation | movement in the heating / cooling simultaneous operation mode (heat radiation load) of an air conditioning apparatus. It is a control block diagram of freeze prevention control of a 1st embodiment. It is a flowchart of the freeze prevention control of 1st Embodiment. It is a flowchart of the freeze prevention control of 2nd Embodiment. It is a flowchart of the freeze prevention control of 3rd Embodiment.

Explanation of symbols

1 Air conditioning equipment (refrigeration equipment)
12 Refrigerant circuit 21 Compression mechanism 23 Heat source side heat exchanger (evaporator)
32, 42, 52 Use side heat exchanger (heat radiator)

Claims (5)

A compression mechanism (21) that compresses the refrigerant, a radiator (32, 42, 52) that radiates the refrigerant compressed in the compression mechanism, and the refrigerant that has radiated heat in the radiator is evaporated by heat exchange with a heat source fluid. A refrigerant circuit (12) configured by connecting an evaporator (23) to be connected;
In order to prevent the heat source fluid from freezing in the evaporator, control is performed to lower the upper limit of the operating capacity of the compression mechanism when a predetermined antifreeze control condition is reached, and / or the compression mechanism is Anti-freezing control means for controlling to stop,
Anti-freezing determination means for determining whether the anti-freezing control condition has been reached,
Freezing prevention setting means for setting information on the heat source fluid;
Anti-freezing changing means for changing the anti-freezing control condition according to information on the heat source fluid set by the anti-freezing setting means;
A refrigeration apparatus (1). The anti-freezing control means has a first anti-freezing control condition corresponding to control for reducing the upper limit of the operating capacity of the compression mechanism (21) and a second anti-freezing control condition for performing control for stopping the compression mechanism. Have
The second antifreeze control condition is a condition that the heat source fluid is more likely to freeze in the evaporator (23) than the first antifreeze control condition.
The refrigeration apparatus (1) according to claim 1.   The refrigeration apparatus (1) according to claim 1 or 2, wherein the freeze prevention control condition is that an evaporation temperature of the refrigerant in the evaporator (23) is equal to or lower than a predetermined lower limit evaporation temperature.   The refrigerant evaporating temperature in the evaporator (23) is obtained by converting the refrigerant pressure detected by a pressure sensor provided between the inlet of the evaporator and the suction side of the compression mechanism (21). The refrigeration apparatus (1) according to claim 3, wherein The freeze prevention setting means includes, as information on the heat source fluid, an inlet temperature of the heat source fluid of the evaporator (23), a target outlet temperature of the heat source fluid of the evaporator, and a circulation flow rate of the heat source fluid of the evaporator. And, when the heat source fluid is a mixed fluid of two or more components, information regarding at least one of the component concentrations can be set,
The anti-freezing control condition includes an inlet temperature of the heat source fluid of the evaporator set by the anti-freezing setting means, a target outlet temperature of the heat source fluid of the evaporator, a circulation flow rate of the heat source fluid of the evaporator, And when the heat source fluid is a mixed fluid of two or more components, the heat source fluid is changed based on at least one of its component concentrations.
The refrigeration apparatus (1) according to any one of claims 1 to 4.

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