WO2014132378A1

WO2014132378A1 - Air conditioning device

Info

Publication number: WO2014132378A1
Application number: PCT/JP2013/055294
Authority: WO
Inventors: 嶋本　大祐; 祐治本村; 孝好本多; 森本　修; 小野　達生; 浩二西岡
Original assignee: 三菱電機株式会社
Priority date: 2013-02-28
Filing date: 2013-02-28
Publication date: 2014-09-04
Also published as: EP2963359A4; EP2963359A1; JP5959716B2; JPWO2014132378A1

Abstract

A heat source-side refrigerant circulation circuit (A) and a heat medium circulation circuit (B) are cascade-connected by an inter-heat medium heat exchanger (15) such that a heat source-side refrigerant and a heat medium exchange heat. A relief valve (60) is provided in the heat medium circulation circuit (B). The relief valve (60) discharges the heat source-side refrigerant and the heat medium and operates when the heat source-side refrigerant flows into the heat medium circulation circuit (B).

Description

Air conditioner

The present invention relates to an air conditioner applied to, for example, a building multi-air conditioner.

Some conventional air conditioners have heat source units (outdoor units) arranged outside the building and indoor units arranged inside the building, such as multi air conditioners for buildings. The refrigerant circulating in the refrigerant circuit of such an air conditioner radiates heat (absorbs heat) to the air supplied to the heat exchanger of the indoor unit, and heats or cools the air. The heated or cooled air is sent into the air-conditioning target space for heating or cooling.

In general, an indoor unit in such a building multi-air conditioner is arranged and used in an indoor space where a person is present (for example, an office, a living room, a store, etc.). Therefore, if the refrigerant leaks from the indoor unit placed in the indoor space for some reason, it is flammable and toxic depending on the type of the refrigerant, which is problematic from the viewpoint of human influence and safety. . Moreover, even if it is a refrigerant | coolant which is not harmful to a human body, the oxygen concentration of indoor space falls by a refrigerant | coolant leak, and it is assumed that a human body is affected.
In order to deal with such problems, a secondary loop system is adopted for the air conditioner, and refrigerant is circulated in the primary loop (outdoor unit system), and water that is not harmful to the secondary loop (indoor unit system). It is conceivable to air-condition an indoor space where people are present using a brine (hereinafter referred to as a heat medium) (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2000-227242 (for example, refer to the summary, FIG. 1)

In the air conditioner as described in Patent Document 1, the refrigerant leakage to the indoor unit basically does not occur, but the heat exchange unit (heat) that exchanges heat between the refrigerant in the primary loop and the heat medium in the secondary loop. In the exchanger), when the heat exchanging portion is damaged and the refrigerant in the primary loop leaks to the secondary loop side, the refrigerant leaks to the indoor unit arranged in the indoor space.
When the refrigerant leakage occurs as described above, the pressure of the secondary loop rises, and this pressure rise causes damage to the parts used in the secondary loop, and further, the refrigerant leakage diffuses due to the damage. there were.

The present invention has been made in order to solve the above-described problems. In a heat exchanging portion where heat is exchanged between the refrigerant in the primary loop and the heat medium in the secondary loop, the heat exchanging portion is damaged and Even when the refrigerant in the next loop leaks to the secondary loop side, the pressure in the secondary loop is suppressed, the damage to the parts used in the secondary loop causing the pressure increase is suppressed, and the diffusion of the refrigerant leak is suppressed. The object is to provide an air conditioner.

The air conditioner according to the present invention includes a compressor, a heat source side heat exchanger, a throttling device, and a heat source side refrigerant flow path of the heat medium side heat exchanger connected in series to circulate the heat source side refrigerant. A circulation circuit, a pump, a use-side heat exchanger, and a heat medium circulation circuit in which heat medium flow paths of the heat exchangers between heat mediums are connected in series to circulate the heat medium, and the heat source side The refrigerant circulation circuit and the heat medium circulation circuit are cascade-connected so that the heat source side refrigerant and the heat medium exchange heat in the inter-heat medium heat exchanger, and a relief valve is provided in the heat medium circulation circuit. The relief valve operates when the heat source side refrigerant flows into the heat medium circulation circuit, and discharges the heat source side refrigerant and the heat medium.

The air conditioner according to the present invention has a relief valve and discharges the heat source side refrigerant mixed with the heat medium out of the secondary loop system even when the refrigerant in the primary loop leaks to the secondary loop side. Therefore, it is possible to suppress the pressure of the secondary loop, suppress the breakage of components used in the secondary loop that causes the pressure increase, and suppress the diffusion of the refrigerant leakage.

It is the schematic which shows the example of installation of the air conditioning apparatus which concerns on embodiment of this invention. It is a 1st refrigerant circuit structural example of the air conditioning apparatus which concerns on embodiment of this invention. It is a 2nd refrigerant circuit structural example of the air conditioning apparatus which concerns on embodiment of this invention. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of the cooling only operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of the heating only operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the cooling main operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of heating main operation mode of the air conditioning apparatus shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings, the relationship of the size of each component may be different from the actual one.
Embodiment.
FIG. 1 is a schematic diagram illustrating an installation example of an air conditioner 100 according to an embodiment of the present invention.
Hereinafter, an installation example of the air conditioner 100 will be described with reference to FIG.
The air conditioner 100 has a refrigeration cycle for circulating refrigerant, and each of the indoor units 2a to 2d can freely select a cooling mode or a heating mode as an operation mode. The air-conditioning apparatus 100 according to the present embodiment includes, for example, a single refrigerant such as R-22, R-32, and R-134a, a pseudo-azeotropic refrigerant mixture such as R-410A and R-404A, and R-407C. Non-azeotropic refrigerants such as CF ₃ CF = CH ₂ containing a double bond in the chemical formula, or a refrigerant or mixture thereof having a relatively low global warming potential, or natural such as CO ₂ or propane Refrigerant is used. Then, a heat source side refrigerant circulation circuit A (hereinafter also referred to as a primary loop) employing these natural refrigerants, and a heat medium circulation circuit B (hereinafter also referred to as a secondary loop) employing water or the like as a heat medium. (See FIG. 2).

The air-conditioning apparatus 100 according to the present embodiment employs a system (indirect system) that indirectly uses a refrigerant (hereinafter referred to as a heat source side refrigerant). That is, the cold or warm heat stored in the heat source side refrigerant is transmitted to a refrigerant (hereinafter referred to as a heat medium) different from the heat source side refrigerant, and the air-conditioning target space is cooled or heated with the cold heat or heat stored in the heat medium. Further, the heat medium can be directly heat exchanged with another heat source such as outdoor air, room air, boiler exhaust heat, etc., and cold heat or heat can be stored in the heat medium.

As shown in FIG. 1, an air-conditioning apparatus 100 according to the present embodiment includes one outdoor unit 1 that is a heat source unit and a plurality of indoor units 2a to 2d (hereinafter simply referred to as indoor unit 2). And a heat medium relay unit 3 interposed between the outdoor unit 1 and the indoor unit 2. The heat medium relay unit 3 performs heat exchange between the heat source side refrigerant and the heat medium. The outdoor unit 1 and the heat medium relay unit 3 are connected by a refrigerant pipe 4 for circulating the heat source side refrigerant. The heat medium converter 3 and the indoor unit 2 are connected by a heat medium pipe 5 for circulating the heat medium. The cold or warm heat generated by the outdoor unit 1 is delivered to the indoor unit 2 via the heat medium converter 3.

The outdoor unit 1 is normally disposed in an outdoor space 6 that is an external space (for example, a rooftop) of a building 9 such as a building, and supplies cold or hot energy to the indoor unit 2 via the heat medium converter 3. It is.
The indoor unit 2 is disposed at a position where cooling air or heating air can be supplied to the indoor space 7 that is a space (for example, a living room) inside the building 9, and the cooling air is supplied to the indoor space 7 that is the air-conditioning target space. Alternatively, heating air is supplied.
The heat medium relay unit 3 is a separate housing from the outdoor unit 1 and the indoor unit 2 and is installed at a position different from the outdoor space 6 and the indoor space 7. The heat medium converter 3 is connected to the outdoor unit 1 via the refrigerant pipe 4 and the indoor unit 2 via the heat medium pipe 5, and cools or warms supplied from the outdoor unit 1 to the indoor unit 2. To communicate.

As shown in FIG. 1, in the air conditioning apparatus 100 according to the present embodiment, an outdoor unit 1 and a heat medium converter 3 are connected via two refrigerant pipes 4, and the heat medium converter 3 and each room Machines 2a to 2d are connected to each other through two heat medium pipes 5. As described above, in the air conditioner 100, construction is facilitated by connecting each unit (the outdoor unit 1, the indoor unit 2, and the heat medium converter 3) via the refrigerant pipe 4 and the heat medium pipe 5. ing.

In FIG. 1, the heat medium relay unit 3 is installed in a space 9 such as the back of the ceiling, which is a space different from the indoor space 7 (for example, a space such as the back of the ceiling in the building 9). However, it may be installed in a common space where there is an elevator. Moreover, although the indoor unit 2 is illustrated as an example of the ceiling cassette type, it is not limited to this. In other words, the indoor unit 2 can be of any type, such as a ceiling-embedded type or a ceiling-suspended type, as long as it can blow heating air or cooling air into the indoor space 7 directly or through a duct. But you can.

The heat medium converter 3 can also be installed in the vicinity of the outdoor unit 1. However, it should be noted that if the distance from the heat medium relay unit 3 to the indoor unit 2 is too long, the heat medium transport power becomes considerably large, and the energy saving effect is diminished.

FIG. 2 is a first refrigerant circuit configuration example of the air-conditioning apparatus 100 according to the embodiment of the present invention.
As shown in FIG. 2, the outdoor unit 1 and the

heat exchangers

15 a and 15 b provided in the heat medium converter 3 are connected to each other via the refrigerant pipe 4. Also, the indoor unit 2 and the heat exchangers between

heat mediums

15a and 15b are also connected via the heat medium pipe 5, respectively.

[Outdoor unit 1]
The outdoor unit 1 stores a compressor 10 that compresses refrigerant, a first refrigerant flow switching device 11 that includes a four-way valve, a heat source side heat exchanger 12 that functions as an evaporator or a condenser, and excess refrigerant. The accumulator 19 is connected and mounted by the refrigerant pipe 4.
In addition, check valves 13a to 13d are provided that can make the flow of the heat-source-side refrigerant flowing into the heat medium relay unit 3 in a certain direction regardless of the operation required by the indoor unit 2.
A check valve 13d is provided in the refrigerant pipe 4 between the

heat exchangers

15a, 15b (hereinafter, simply referred to as the heat exchanger 15) and the first refrigerant flow switching device 11, A check valve 13b is provided in the first connection pipe 4a, a check valve 13c is provided in the second connection pipe 4b, and a check valve is provided in the refrigerant pipe 4 between the heat source side heat exchanger 12 and the

heat exchangers

15a and 15b. 13a are provided.

The compressor 10 sucks the heat source side refrigerant and compresses the heat source side refrigerant to a high temperature / high pressure state, and may be configured by, for example, an inverter compressor capable of capacity control.
The first refrigerant flow switching device 11 has a flow of the heat source side refrigerant in the heating operation mode (in the heating only operation mode and in the heating main operation mode) and the cooling operation mode (in the cooling only operation mode and the cooling main operation mode). The flow of the heat source side refrigerant at the time) is switched.
The heat source side heat exchanger 12 functions as an evaporator during heating operation, functions as a condenser during cooling operation, and performs heat exchange between air supplied from a blower such as a fan (not shown) and the heat source side refrigerant. Is.

Here, the all-cooling operation mode is a mode in which all the driven indoor units 2 execute a cooling operation, and the all-heating operation mode is a mode in which all the driven indoor units 2 perform a heating operation, The main operation mode is a cooling / heating mixed operation mode in which both cooling operation and heating operation are mixed, the cooling load is larger, and the heating main operation mode is also the cooling / heating mixed operation mode, and the heating load is more It ’s a big mode.

The accumulator 19 is provided on the suction side of the compressor 10 and has a function of storing excess refrigerant and a function of separating liquid refrigerant and gas refrigerant. In addition, the accumulator 19 should just be a container which can store an excessive refrigerant | coolant.

Further, a second pressure sensor 37 and a third pressure sensor 38, which are pressure detection devices, are provided before and after the compressor 10, and the rotational speed of the compressor 10, the second pressure sensor 37, and the third pressure sensor are provided. The refrigerant flow rate from the compressor 10 can be calculated from the 38 detected values.

[Indoor unit 2]
The four indoor units 2a to 2d are equipped with use side heat exchangers 26a to 26d (hereinafter sometimes simply referred to as use side heat exchangers 26), respectively. The use-side heat exchanger 26 is connected to the heat medium flow control devices 25a to 25d (hereinafter simply referred to as the heat medium flow control device 25) provided in the heat medium converter 3 via the heat medium pipe 5. Are connected to second heat medium flow switching devices 23a to 23d (hereinafter sometimes simply referred to as second heat medium flow switching device 23).
The use side heat exchanger 26 performs heat exchange between air supplied from a blower such as a fan (not shown) and a heat medium, and generates cooling air or heating air to be supplied to the indoor space 7. To do.
The indoor units 2a to 2d are respectively provided with intake air temperature detection devices 39a to 39d for detecting the intake temperature.

[Heat medium converter 3]
The heat medium relay unit 3 includes two

heat exchangers

15a and 15b (hereinafter, simply referred to as the heat exchanger 15) that exchange heat between the refrigerant and the heat medium, and depressurize the refrigerant. Two

expansion devices

16a and 16b (hereinafter simply referred to as the expansion device 16), and two open /

close devices

17a and 17b (hereinafter also simply referred to as the open / close device 17) for opening and closing the flow path of the refrigerant pipe 4. , Two second refrigerant

flow switching devices

18a and 18b (hereinafter sometimes simply referred to as second refrigerant flow switching device 18) for switching the refrigerant flow channels, and two

pumps

21a and 21b (hereinafter referred to as the second refrigerant flow switching device 18). The first heat medium flow switching devices 22a to 22d (hereinafter simply referred to as the first heat medium flow switching device 22) connected to one of the heat medium pipes 5 (sometimes simply referred to as a pump 21). There is), heat Four second heat medium flow switching devices 23 connected to the other of the body piping 5, 4 connected to the heat medium piping 5 between the first heat medium flow switching device 22 and the use side heat exchanger 26. The two

relief valves

60a and 60b for discharging the heat medium to the outside of the system (for example, inside the heat medium converter 3) when the pressure of the two heat medium flow control devices 25a to 25d and the secondary loop rises to a predetermined value. (Hereinafter may be simply referred to as relief valve 60).

The two heat exchangers between

heat mediums

15a and 15b function as condensers (radiators) or evaporators, perform heat exchange between the heat source side refrigerant and the heat medium, and are generated by the outdoor unit 1 and stored in the heat source side refrigerant. The generated cold or warm heat is transmitted to the heat medium. The heat exchanger related to heat medium 15a is provided between the expansion device 16a and the second refrigerant flow switching device 18a in the heat source side refrigerant circulation circuit A, and cools the heat medium in the cooling / heating mixed operation mode. It is something to offer. The heat exchanger related to heat medium 15b is provided between the expansion device 16b and the second refrigerant flow switching device 18b in the heat source side refrigerant circulation circuit A, and is used to heat the heat medium in the cooling / heating mixed operation mode. It is something to offer. In addition, it is good to comprise the

heat exchangers

15a and 15b between heat media with a double-pipe heat exchanger and a plate heat exchanger, for example.

The two

expansion devices

16a and 16b function as a pressure reducing valve and an expansion valve, and expand the heat source side refrigerant by reducing the pressure. The expansion device 16a is provided on the upstream side of the heat exchanger related to heat medium 15a in the flow of the heat source side refrigerant in the cooling only operation mode. The expansion device 16b is provided on the upstream side of the heat exchanger related to heat medium 15b in the flow of the heat source side refrigerant in the cooling only operation mode. Note that the two expansion devices 16 may be configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve.

The two opening /

closing devices

17a and 17b open and close the refrigerant pipe 4, and may be constituted by, for example, a two-way valve.

The two second refrigerant

flow switching devices

18a and 18b are configured by four-way valves or the like, and switch the flow of the heat source side refrigerant according to the operation mode. The second refrigerant flow switching device 18a is provided on the downstream side of the heat exchanger related to heat medium 15a in the flow of the heat source side refrigerant in the cooling only operation mode. The second refrigerant flow switching device 18b is provided on the downstream side of the heat exchanger related to heat medium 15b in the flow of the heat source side refrigerant in the cooling only operation mode.

The two pumps 21 a and 21 b circulate the heat medium in the heat medium pipe 5. The pump 21 a is provided in the heat medium pipe 5 between the heat exchanger related to heat medium 15 a and the second heat medium flow switching device 23. The pump 21 b is provided in the heat medium pipe 5 between the heat exchanger related to heat medium 15 b and the second heat medium flow switching device 23. The two pumps 21 may be constituted by, for example, pumps capable of capacity control. The pump 21a is connected to the heat medium pipe 5 between the heat exchanger related to heat medium 15a and the first heat medium flow switching device 22, and the pump 21b is switched to the heat exchanger related to heat medium 15b and the first heat medium flow switching. You may provide in the heat medium piping 5 between the apparatuses 22, respectively.

The four first heat medium flow switching devices 22a to 22d are configured by three-way valves or the like, and switch the heat medium flow paths. The number of first heat medium flow switching devices 22 is set according to the number of indoor units 2 installed (four in the present embodiment). The first heat medium flow switching device 22 includes one of the three heat transfer medium heat exchangers 15a, one of the other heat transfer medium heat exchangers 15b, and the other one of the heat medium flow control devices. 25 to the outlet side of the heat medium flow path of the use side heat exchanger 26, respectively.
The first heat medium flow switching devices 22a to 22d correspond to the indoor units 2a to 2d as the first heat medium

flow switching devices

22a, 22b, 22c, and 22d from the lower side of the drawing, and they are heat medium conversions. Although it is illustrated as being installed in the machine 3, a larger number may be provided.

The four second heat medium flow switching devices 23a to 23d are configured by three-way valves or the like, and switch the flow path of the heat medium. The second heat medium flow switching device 23 is provided with a number (four in the present embodiment) corresponding to the number of indoor units 2 installed. In the second heat medium flow switching device 23, one of the three sides is the heat exchanger related to heat medium 15 a, one of the other is the heat exchanger related to heat medium 15 b, and the other is the use side heat exchanger. 26, and connected to the inlet side of the heat medium flow path of the use side heat exchanger 26, respectively.
The second heat medium flow switching devices 23a to 23d correspond to the indoor units 2a to 2d as the second heat medium

flow switching devices

23a, 23b, 23c, and 23d from the lower side of the drawing, and they are heat medium conversions. Although it is illustrated as being installed in the machine 3, a larger number may be provided.

The four heat medium flow control devices 25a to 25d are configured by two-way valves or the like capable of controlling the opening area, and adjust the flow rate of the heat medium flowing through the heat medium pipe 5. The number of heat medium flow control devices 25 according to the number of indoor units 2 installed (four in this embodiment) is provided. One of the heat medium flow control devices 25 is connected to the use side heat exchanger 26 and the other is connected to the first heat medium flow switching device 22, and is connected to the outlet side of the heat medium flow channel of the use side heat exchanger 26. Each is provided.
Note that the heat medium flow control devices 25a to 25d correspond to the indoor units 2a to 2d from the bottom of the page to the heat medium

flow control devices

25a, 25b, 25c, and 25d, and are installed in the heat medium converter 3. However, a larger number may be provided. Further, the heat medium flow control device 25 may be provided on the inlet side of the heat medium flow path of the use side heat exchanger 26.

[Relief valve 60]
The two

relief valves

60a and 60b are respectively provided in the heat medium pipe 5 on the outlet side of the

pumps

21a and 21b, and operate when the pressure of the secondary loop rises to a predetermined value (operating pressure). Is discharged out of the system.
The operating pressure of the relief valve 60 is determined from the type of heat source side refrigerant and the type of heat medium.
Further, in the air conditioner 100 according to the present embodiment, the increase in the pressure of the secondary loop is caused by freezing of the heat medium on the secondary loop side, corrosion between the heat medium and the heat exchanger 15 between the heat medium, or the like. Thus, it is assumed that a communication hole is opened between the primary loop and the secondary loop of the heat exchanger related to heat medium 15. Therefore, the Cv value (Cv [60a] + Cv [60b]), which is a coefficient representing the flow rate characteristic of the relief valve 60, is as follows.
Cv [60a] + Cv [60b] = Cv1 × (P1-P2) ^1/2 / (P2) ^1/2
P1: Maximum pressure of the heat source side refrigerant (maximum pressure of the primary loop)
P2: Operating pressure of relief valve Cv1: Cv value of communication hole opened between primary loop and secondary loop Cv [60a]: Cv value of relief valve 60a Cv [60b]: Cv value of relief valve 60b For example, P1 is 3.8 MPa when the refrigerant of the primary loop is R410A, and P2 is 0.4 MPa, which is the sum of the average pressure of the heat medium 0.2 MPa and the maximum head loss 0.2 MPa of the pump 21. When it is, it becomes as follows.
Cv [60a] + Cv [60b] = Cv1 × (3.4) ^1/2 /(0.4) ^1/2 = 2.92 × Cv1

Furthermore, for example, when Cv1 is a pinhole due to corrosion of copper piping, it is about 1 mm ² , so the Cv value of the relief valve 60 that is the sum of Cv [60a] + Cv [60b] is 3 mm ² or more in total. Necessary.
If the operating pressure of the relief valve 60 is determined according to the maximum pressure of only the heat medium, when the heat source side refrigerant leaks into the secondary loop, the relief valve 60 is activated as the secondary loop suddenly increases in pressure. However, there is a possibility that the pressure rise cannot be released and the pressure resistance of the parts used in the secondary loop is exceeded, resulting in damage. Therefore, the operating pressure of the relief valve 60 is determined based on the type of the heat medium and the type of the heat source side refrigerant in consideration of the pressure that varies depending on the type of the heat source side refrigerant. In addition, the size of the relief valve 60 is selected according to the maximum pressure of the heat medium and the maximum pressure of the heat source side refrigerant, and the flow rate to be discharged out of the system is determined (adjusted), so that the secondary loop is adjusted to an appropriate pressure. I try to keep it.

FIG. 3 is a second refrigerant circuit configuration example of the air-conditioning apparatus 100 according to the embodiment of the present invention.
As shown in FIG. 2, in the first refrigerant circuit configuration example, the

relief valves

60a and 60b are provided in the heat medium pipes 5 on the outlet sides of the

pumps

21a and 21b, respectively. The relief valve 60b may be omitted by connecting the heat medium pipe 5 on the discharge side of the pump 21a and the heat medium pipe 5 on the discharge side of the pump 21b with a thin pipe. Further, a heat medium pressure detecting device 62 for detecting the pressure of the secondary loop may be provided in the heat medium pipe 5 on the outlet side of the pump 21b.

As shown in FIGS. 2 and 3, the heat medium relay 3 includes two

first temperature sensors

31a and 31b (hereinafter simply referred to as the first temperature sensor 31) and four second temperature sensors 34a. 34d (hereinafter sometimes simply referred to as the second temperature sensor 34), four third temperature sensors 35a to 35d (hereinafter sometimes simply referred to as the third temperature sensor 35), a fourth temperature sensor 50, and Various detection means of the first pressure sensor 36 are provided. Information (for example, temperature information and pressure information) detected by these detection means is sent to a control device 52 (which will be described later) for overall control of the operation of the air conditioner 100, and the compressor 10 driving frequency, rotation speed of a blower (not shown) provided in the vicinity of the heat source side heat exchanger 12 and the use side heat exchanger 26, switching of the first refrigerant flow switching device 11, driving frequency of the pump 21, second This is used for control such as switching of the refrigerant flow switching device 18.

In addition to the above, the heat medium relay 3 is provided with a refrigerant leakage detection device 61 at or near the heat exchanger 15 between the heat media, and the information is notified to the arithmetic device 52a shown below. .

The control device 52 is configured by a microcomputer or the like, and calculates an evaporation temperature, a condensation temperature, a saturation temperature, a superheat degree, and a supercooling degree based on the calculation result of the arithmetic device 52a. Then, based on the calculation results, the control device 52 determines the opening degree of the expansion device 16, the rotational speed of the compressor 10, and the fan speeds of the heat source side heat exchanger 12 and the use side heat exchanger 26 (ON / OFF Etc.) so that the performance of the air conditioner 100 is maximized.
In addition, the control device 52 determines the drive frequency of the compressor 10, the rotational speed of the blower (including ON / OFF), the first refrigerant flow switching device 11 based on detection information from various detection means and instructions from the remote controller. Switching, driving of the pump 21, opening of the expansion device 16, opening and closing of the switching device 17, switching of the second refrigerant channel switching device 18, switching of the first heat medium channel switching device 22, switching of the second heat medium channel The switching of the device 23 and the opening degree of the heat medium flow control device 25 are controlled. That is, the control device 52 performs overall control of various devices in order to execute each operation mode described later.
Note that the control device 57 is also provided in the outdoor unit 1 and controls the actuator of the outdoor unit 1 based on information transmitted from the control device 52 of the heat medium relay unit 3.
In the present embodiment, the control device 52 of the heat medium relay unit 3 is described as being separate from the arithmetic unit 57a provided in the outdoor unit 1, but may be the same unit.

The two

first temperature sensors

31a and 31b detect the temperature of the heat medium flowing out from the intermediate heat exchanger 15, that is, the temperature of the heat medium at the outlet of the intermediate heat exchanger 15. For example, the thermistor It is good to comprise. The first temperature sensor 31a is provided in the heat medium pipe 5 on the inlet side of the pump 21a. The first temperature sensor 31b is provided in the heat medium pipe 5 on the inlet side of the pump 21b.

The four second temperature sensors 34 a to 34 d are respectively provided between the first heat medium flow switching device 22 and the heat medium flow control device 25, and from the use side heat exchanger (or heat recovery heat exchanger) 26. It detects the temperature of the heat medium that has flowed out, and may be composed of a thermistor or the like. The number of the second temperature sensors 34 according to the number of installed indoor units 2 (four in the present embodiment) is provided. The second temperature sensors 34a to 34d are shown as

second temperature sensors

34a, 34b, 34c, and 34d from the lower side of the drawing corresponding to the indoor unit 2.

The four third temperature sensors 35a to 35d are provided on the inlet side or the outlet side of the heat source side refrigerant of the heat exchanger related to heat medium 15, and the temperature or heat medium of the heat source side refrigerant flowing into the heat exchanger related to heat medium 15 The temperature of the heat source side refrigerant that has flowed out of the intermediate heat exchanger 15 is detected, and it may be constituted by a thermistor or the like. The third temperature sensor 35a is provided between the heat exchanger related to heat medium 15a and the second refrigerant flow switching device 18a. The third temperature sensor 35b is provided between the heat exchanger related to heat medium 15a and the expansion device 16a. The third temperature sensor 35c is provided between the heat exchanger related to heat medium 15b and the second refrigerant flow switching device 18b. The third temperature sensor 35d is provided between the heat exchanger related to heat medium 15b and the expansion device 16b.

The fourth temperature sensor 50 obtains temperature information used when calculating the evaporation temperature and the dew point temperature, and is provided between the expansion device 16a and the expansion device 16b.

The first pressure sensor 36 obtains pressure information for conversion into a saturation temperature used when controlling the opening degree of the expansion device 16, and is provided between the heat exchanger related to heat medium 15b and the expansion device 16b. Is provided.

The heat medium pipe 5 for circulating the heat medium is composed of one connected to the heat exchanger related to heat medium 15a and one connected to the heat exchanger related to heat medium 15b. Each branch is branched (four branches in this embodiment) according to the number of indoor units 2 connected to the medium converter 3. The heat medium pipe 5 connected to the inlet side of the heat exchanger related to heat medium 15a and the heat medium pipe 5 connected to the inlet side of the heat exchanger related to heat medium 15b are respectively connected to the first heat medium flow switching device. 22, the heat medium pipe 5 connected to the outlet side of the intermediate heat exchanger 15a and the heat medium pipe 5 connected to the outlet side of the intermediate heat exchanger 15b are respectively connected to the second heat medium flow. They are connected by a path switching device 23.
Then, by controlling the first heat medium flow switching device 22 and the second heat medium flow switching device 23, the heat medium from the heat exchanger related to heat medium 15a flows into the use-side heat exchanger 26, or It is determined whether the heat medium from the heat exchanger related to heat medium 15b is caused to flow into the use side heat exchanger 26 or not.

[Description of operation mode]
The air conditioner 100 includes a compressor 10, a first refrigerant flow switching device 11, a heat source side heat exchanger 12, an opening / closing device 17, an expansion device 16, a heat source side refrigerant flow path of the heat exchanger related to heat medium 15a, a second A refrigerant flow switching device 18 and an accumulator 19 are connected by a refrigerant pipe 4 to constitute a heat source side refrigerant circulation circuit A.
Further, the heat medium flow path of the heat exchanger related to heat medium 15a, the pump 21, the second heat medium flow path switching device 23, the use side heat exchanger 26, the heat medium flow control device 25, and the first heat medium flow path. The switching device 22 is connected by the heat medium pipe 5 to constitute the heat medium circulation circuit B. That is, a plurality of usage-side heat exchangers 26 are connected in parallel to the

heat exchangers

15a and 15b, respectively, and the heat medium circulation circuit B has a plurality of systems.

Therefore, in the air conditioner 100, the outdoor unit 1 and the heat medium relay unit 3 are connected via the

heat exchangers

15a and 15b provided between the heat medium relay unit 3 and the heat medium relay unit 3 And the indoor unit 2 are connected to each other via the

heat exchangers

15a and 15b. That is, in the air conditioner 100, the heat source side refrigerant circulating in the heat source side refrigerant circulation circuit A and the heat medium circulating in the heat medium circulation circuit B exchange heat with each other between the

heat exchangers

15a and 15b. It has become.

Hereinafter, each operation mode executed by the air conditioner 100 will be described. The air conditioner 100 can perform a cooling operation or a heating operation in the indoor unit 2 based on an instruction from each indoor unit 2. That is, the air conditioner 100 can perform the same operation for all the indoor units 2 and can perform different operations for each of the indoor units 2.

There are four operation modes executed by the air conditioner 100: a cooling only operation mode, a heating only operation mode, a cooling main operation mode, and a heating main operation mode. Hereinafter, each operation mode will be described together with the flow of the heat source side refrigerant and the heat medium.

[Cooling operation mode]
FIG. 4 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 illustrated in FIG. 2 is in the cooling only operation mode. In FIG. 4, the cooling only operation mode will be described by taking as an example a case where a cooling load is generated in the

indoor units

2 a and 2 b of the use

side heat exchangers

26 a and 26 b. Also, the pipes represented by the thick lines indicate the pipes through which the refrigerant (heat source side refrigerant and heat medium) flows, the flow direction of the heat source side refrigerant is indicated by solid line arrows, and the flow direction of the heat medium is indicated by broken line arrows.

4, in the cooling only operation mode shown in FIG. 4, in the outdoor unit 1, the first refrigerant flow switching device 11 is switched so that the heat source side refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12. In the heat medium relay 3, the

pumps

21 a and 21 b are driven, the heat medium

flow control devices

25 a and 25 b are opened, the heat medium

flow control devices

25 c and 25 d are closed, and the

heat exchangers

15 a and 15 b and the use side The heat medium circulates between the

heat exchangers

26a and 26b.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. And it becomes a high-pressure liquid refrigerant, radiating heat to outdoor air with the heat source side heat exchanger 12. The high-pressure refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 through the check valve 13 a, and flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-pressure refrigerant that has flowed into the heat medium relay unit 3 is branched into the expansion device 16a side and the expansion device 16b side after passing through the opening / closing device 17a. Then, it is expanded by the

expansion devices

16a and 16b to become a low-temperature and low-pressure two-phase refrigerant. The opening / closing device 17b is closed.

This two-phase refrigerant flows into each of the

heat exchangers

15a and 15b acting as an evaporator and absorbs heat from the heat medium circulating in the heat medium circuit B, thereby cooling the heat medium at a low temperature / It becomes a low-pressure gas refrigerant. The gas refrigerant flowing out of the

heat exchangers

15a and 15b flows out of the heat medium converter 3 through the second refrigerant

flow switching devices

18a and 18b, and flows into the outdoor unit 1 again through the refrigerant pipe 4. To do. The refrigerant flowing into the outdoor unit 1 passes through the check valve 13d and is sucked into the compressor 10 again via the first refrigerant flow switching device 11 and the accumulator 19.

At this time, the second refrigerant

flow switching devices

18a and 18b communicate with the low-pressure pipe. Further, the expansion device 16a has an opening degree so that a superheat (superheat degree) obtained as a difference between the temperature detected by the third temperature sensor 35a and the temperature detected by the third temperature sensor 35b is constant. Is controlled. Similarly, the opening degree of the expansion device 16b is controlled so that the superheat obtained as the difference between the temperature detected by the third temperature sensor 35c and the temperature detected by the third temperature sensor 35d becomes constant. The

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the cooling only operation mode, the cold heat of the heat source side refrigerant is transmitted to the heat medium in each of the

heat exchangers

15a and 15b, and the cooled heat medium is caused to flow in the heat medium pipe 5 by the

pumps

21a and 21b, respectively. It will be. The heat medium pressurized and discharged by the

pumps

21a and 21b flows into the use

side heat exchangers

26a and 26b via the second heat medium

flow switching devices

23a and 23b. The heat medium absorbs heat from the indoor air in the use

side heat exchangers

26a and 26b, thereby cooling the indoor space 7.

Then, the heat medium flows out from the use

side heat exchangers

26a and 26b and flows into the heat medium

flow control devices

25a and 25b. At this time, the flow rate of the heat medium is controlled to a flow rate necessary to cover the air conditioning load required indoors by the action of the heat medium flow

rate adjusting devices

25a and 25b, and flows into the use

side heat exchangers

26a and 26b. It is like that. The heat medium flowing out of the heat medium

flow control devices

25a and 25b flows into the

heat exchangers

15a and 15b through the first heat medium

flow switching devices

22a and 22b, and is sucked into the

pumps

21a and 21b again. .

Note that, in the heat medium pipe 5 of the use

side heat exchangers

26a and 26b, the first heat medium flow switching device from the second heat medium

flow switching devices

23a and 23b via the heat medium

flow control devices

25a and 25b. The heat medium flows in the direction to 22a and 22b. The air conditioning load required in the indoor space 7 includes the temperature detected by the first temperature sensor 31a, the temperature detected by the first temperature sensor 31b, and the second temperature sensor 34a (or the second temperature sensor 34b). ) Can be covered by controlling so as to keep the difference between the detected temperature and the target value as a target value. As the outlet temperature of the

heat exchangers

15a and 15b, the temperature of either the

first temperature sensor

31a or 31b may be used, or the average temperature of these may be used. At this time, the first heat medium flow switching device 22 and the second heat medium flow switching device 23 are provided with an intermediate opening so as to secure a flow path that flows to both the

heat exchangers

15a and 15b. It is in degrees.

When the cooling only operation mode is executed, it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) having no heat load. The heat medium is prevented from flowing to the heat exchanger 26. In FIG. 4, the use

side heat exchangers

26 a and 26 b have a heat load, and thus a heat medium flows. However, since the use

side heat exchangers

26 c and 26 d are not operated, the corresponding heat medium flow control devices 25 c and The heat medium flow control device 25d is fully closed. When a heat load is generated in the use side heat exchanger 26 or when the heat recovery machine is operated, the heat medium flow control device 25 may be opened to circulate the heat medium.
The same applies to the heating only operation mode, the cooling main operation mode, and the heating main operation mode.

The refrigerant whose temperature is detected by the fourth temperature sensor 50 is a liquid refrigerant, and the liquid inlet enthalpy is calculated by the arithmetic unit 52a based on this temperature information. Further, the temperature of the low-pressure two-phase temperature state is detected from the third temperature sensor 35d, and the saturated liquid enthalpy and saturated gas enthalpy are calculated by the arithmetic unit 52a based on this temperature information. Based on these pieces of information, the evaporation temperature Te ^* and the dew point temperature Tdew ^* are obtained by the method described later.

[Heating operation mode]
FIG. 5 is a refrigerant circuit diagram showing a refrigerant flow when the air-conditioning apparatus 100 shown in FIG. 2 is in the heating only operation mode. In FIG. 4, the heating only operation mode will be described by taking as an example a case where a thermal load is generated in the use

side heat exchangers

26 a and 26 b. Moreover, the pipes represented by the thick lines indicate the pipes through which the refrigerant flows, and the flow direction of the heat source side refrigerant is indicated by solid line arrows and the flow direction of the heat medium is indicated by broken line arrows.

In the heating only operation mode shown in FIG. 5, in the outdoor unit 1, the first refrigerant flow switching device 11 causes the heat source side refrigerant discharged from the compressor 10 to heat without passing through the heat source side heat exchanger 12. It switches so that it may flow into the media converter 3. In the heat medium relay unit 3, the

pumps

21a and 21b are driven, the heat medium

flow control devices

25a and 25b are opened, the heat medium

flow control devices

25c and 25d are closed, and the

heat exchangers

15a and 15b are used. The heat medium is circulated between the

side heat exchangers

26a and 26b.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the first refrigerant flow switching device 11 and the check valve 13b. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-temperature and high-pressure gas refrigerant flowing into the heat medium relay unit 3 is branched into the second refrigerant flow switching device 18a side and the second refrigerant flow switching device 18b side. Then, the heat flows through the second refrigerant flow switching device 18a and the second refrigerant flow switching device 18b and flows into the

heat exchangers

15a and 15b, respectively.

The high-temperature and high-pressure gas refrigerant flowing into the

heat exchangers

15a and 15b becomes high-pressure liquid refrigerant while radiating heat to the heat medium circulating in the heat medium circuit B. The liquid refrigerant flowing out of the heat exchangers between

heat mediums

15a and 15b is expanded by the

expansion devices

16a and 16b to become a low-temperature and low-pressure two-phase refrigerant. The two-phase refrigerant flows out of the heat medium relay unit 3 through the opening / closing device 17b, and flows into the outdoor unit 1 through the refrigerant pipe 4 again. The opening / closing device 17a is closed.

The refrigerant flowing into the outdoor unit 1 flows into the heat source side heat exchanger 12 acting as an evaporator through the check valve 13c. And the refrigerant | coolant which flowed into the heat source side heat exchanger 12 absorbs heat from outdoor air in the heat source side heat exchanger 12, and becomes a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant flowing out from the heat source side heat exchanger 12 is again sucked into the compressor 10 via the first refrigerant flow switching device 11 and the accumulator 19.

At this time, the second refrigerant

flow switching devices

18a and 18b communicate with the high-pressure pipe. Further, the expansion device 16a has a subcool (degree of subcooling) obtained as a difference between the value detected by the first pressure sensor 36 converted to the saturation temperature and the temperature detected by the third temperature sensor 35b. The opening degree is controlled to be constant. Similarly, in the expansion device 16b, a subcool obtained as a difference between a value obtained by converting the pressure detected by the first pressure sensor 36 into a saturation temperature and a temperature detected by the third temperature sensor 35d is constant. The opening degree is controlled. If the temperature at the intermediate position of the heat exchanger related to heat medium 15 can be measured, the temperature at the intermediate position may be used instead of the first pressure sensor 36, and the system can be configured at low cost.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the heating only operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in each of the

heat exchangers

15a and 15b, and the heated heat medium is caused to flow in the heat medium pipe 5 by the

pumps

21a and 21b flows into the use

side heat exchangers

26a and 26b via the second heat medium

flow switching devices

23a and 23b. Then, the indoor space 7 is heated by the heat medium radiating heat to the indoor air by the use

side heat exchangers

26a and 26b.

Then, the heat medium flows out from the use

side heat exchangers

26a and 26b and flows into the heat medium

flow control devices

rate adjusting devices

25a and 25b, and flows into the use

side heat exchangers

26a and 26b. It is like that. The heat medium flowing out of the heat medium

flow control devices

25a and 25b flows into the

heat exchangers

15a and 15b through the first heat medium

flow switching devices

22a and 22b, and is sucked into the

pumps

21a and 21b again. .

Note that, in the heat medium pipe 5 of the use

side heat exchangers

flow switching devices

23a and 23b via the heat medium

flow control devices

25a and 25b. The heat medium flows in the direction to 22a and 22b. The air conditioning load required in the indoor space 7 is detected by the temperature detected by the first temperature sensor 31a, the temperature detected by the first temperature sensor 31b, and the

second temperature sensors

34a and 34b. This can be covered by controlling so as to keep the difference from the temperature as a target value. As the outlet temperature of the

heat exchangers

15a and 15b, the temperature of either the

first temperature sensor

31a or 31b may be used, or the average temperature of these may be used.

At this time, the first heat medium flow switching device 22 and the second heat medium flow switching device 23 are provided with an intermediate opening so as to secure a flow path that flows to both the

heat exchangers

15a and 15b. It is in degrees. In addition, the usage-side heat exchanger 26 should be controlled by the temperature difference between the inlet and the outlet, but the temperature of the heat medium on the inlet side of the usage-side heat exchanger 26 is detected by the first temperature sensor 31b. By using the first temperature sensor 31b, the number of temperature sensors can be reduced and the system can be configured at low cost.

[Cooling operation mode]
FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 illustrated in FIG. 2 is in the cooling main operation mode. In FIG. 6, the cooling main operation mode will be described by taking as an example a case where a heating load is generated in the use side heat exchanger 26d and a cooling load is generated in the use side heat exchangers 26a to 26c. In addition, the pipes represented by the bold lines indicate the pipes through which the refrigerant (heat source side refrigerant and heat medium) circulates, and the flow direction of the heat source side refrigerant is indicated by a solid line arrow and the flow direction of the heat medium is indicated by a broken line arrow. .

In the cooling main operation mode shown in FIG. 6, in the outdoor unit 1, the first refrigerant flow switching device 11 is switched so that the heat source side refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12. In the heat medium relay unit 3, the

pumps

21a and 21b are driven to open the heat medium flow control devices 25a to 25d, and between the heat exchanger related to heat medium 15a and the use side heat exchangers 26a to 26c, and the heat medium. The heat medium circulates between the intermediate heat exchanger 15b and the use side heat exchanger 26d.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. And it becomes a liquid refrigerant, dissipating heat to outdoor air with the heat source side heat exchanger 12. The refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 and flows into the heat medium relay unit 3 through the check valve 13 a and the refrigerant pipe 4. The refrigerant that has flowed into the heat medium relay unit 3 flows into the heat exchanger related to heat medium 15b that acts as a condenser through the second refrigerant flow switching device 18b.

The refrigerant that has flowed into the heat exchanger related to heat medium 15b becomes a refrigerant whose temperature is further lowered while radiating heat to the heat medium circulating in the heat medium circuit B. The refrigerant flowing out of the heat exchanger related to heat medium 15b is expanded by the expansion device 16b and becomes a low-pressure two-phase refrigerant. This low-pressure two-phase refrigerant flows into the heat exchanger related to heat medium 15a acting as an evaporator via the expansion device 16a. The low-pressure two-phase refrigerant that has flowed into the heat exchanger related to heat medium 15a absorbs heat from the heat medium circulating in the heat medium circuit B, and becomes a low-pressure gas refrigerant while cooling the heat medium. The gas refrigerant flows out of the heat exchanger related to heat medium 15a, flows out of the heat medium converter 3 via the second refrigerant flow switching device 18a, and flows into the outdoor unit 1 again through the refrigerant pipe 4. The refrigerant that has flowed into the outdoor unit 1 is again sucked into the compressor 10 via the check valve 13d, the first refrigerant flow switching device 11, and the accumulator 19.

At this time, the second refrigerant flow switching device 18a is in communication with the low pressure pipe, while the second refrigerant flow switching device 18b is in communication with the high pressure side piping. Further, the opening degree of the expansion device 16b is controlled so that the superheat obtained as the difference between the temperature detected by the third temperature sensor 35a and the temperature detected by the third temperature sensor 35b becomes constant. . Further, the expansion device 16a is fully opened, and the opening /

closing devices

17a and 17b are closed. The expansion device 16b is configured so that a subcool obtained as a difference between a value obtained by converting the pressure detected by the first pressure sensor 36 into a saturation temperature and a temperature detected by the third temperature sensor 35d is constant. The opening degree may be controlled. Alternatively, the expansion device 16b may be fully opened, and the superheat or subcool may be controlled by the expansion device 16a.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the cooling main operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in the heat exchanger related to heat medium 15b, and the heated heat medium is caused to flow in the heat medium pipe 5 by the pump 21b. Further, the cold heat of the heat source side refrigerant is transmitted to the heat medium by the heat exchanger related to heat medium 15a, and the cooled heat medium is caused to flow in the heat medium pipe 5 by the pump 21a. The heat medium pressurized and discharged by the

pumps

21a and 21b flows into the use side heat exchangers 26a to 26d via the second heat medium flow switching devices 23a to 23d.

In the use side heat exchanger 26d, the heat medium radiates heat to the indoor air, thereby heating the indoor space 7. In the use side heat exchangers 26a to 26c, the heat medium absorbs heat from the indoor air, thereby cooling the indoor space 7. At this time, the flow rate of the heat medium is controlled to a flow rate necessary to cover the air conditioning load required indoors by the action of the heat medium flow rate adjusting devices 25a to 25d, and flows into the use side heat exchangers 26a to 26d. It is like that.
The heat medium that has passed through the use-side heat exchanger 26d and has slightly decreased in temperature passes through the heat medium flow control device 25d and the first heat medium flow switching device 22d, flows into the heat exchanger related to heat medium 15b, and again It is sucked into the pump 21b.
In addition, the heat medium that has passed through the use side heat exchangers 26a to 26c and slightly increased in temperature passes through the heat medium flow control devices 25a to 25c and the first heat medium flow switching devices 22a to 22c, and heat between the heat media. It flows into the exchanger 15a and is sucked into the pump 21a again.

During the execution of the cooling main operation mode, the warm heat medium and the cold heat medium are respectively mixed with the heat load without being mixed by the action of the first heat medium flow switching device 22 and the second heat medium flow switching device 23. Then, it is introduced into the use side heat exchangers 26a to 26d having a cold load.
In the heat medium pipe 5 of the use side heat exchangers 26a to 26d, the first heat medium flow is supplied from the second heat medium flow switching device 23 via the heat medium flow control device 25 on both the heating side and the cooling side. A heat medium flows in the direction to the path switching device 22.
The air conditioning load required in the indoor space 7 is the difference between the temperature detected by the first temperature sensor 31b on the heating side and the temperature detected by the second temperature sensor 34d on the heating side, and the first on the cooling side. This can be covered by controlling the difference between the temperature detected by the two temperature sensors 34a to 34c and the temperature detected by the first temperature sensor 31a as a target value.

[Heating main operation mode]
FIG. 7 is a refrigerant circuit diagram showing a refrigerant flow when the air-conditioning apparatus 100 shown in FIG. 2 is in the heating main operation mode. In FIG. 7, the heating main operation mode will be described by taking as an example a case where a heat load is generated in the use side heat exchangers 26b to 26d and a heat load is generated in the use side heat exchanger 26a. In addition, the pipes represented by the bold lines indicate the pipes through which the refrigerant (heat source side refrigerant and heat medium) circulates, and the flow direction of the heat source side refrigerant is indicated by a solid line arrow and the flow direction of the heat medium is indicated by a broken line arrow. .

In the heating-main operation mode shown in FIG. 7, in the outdoor unit 1, the first refrigerant flow switching device 11 uses the heat source side refrigerant discharged from the compressor 10 without passing through the heat source side heat exchanger 12. It switches so that it may flow into converter 3. In the heat medium relay unit 3, the

pumps

21a and 21b are driven, the heat medium flow control devices 25a to 25d are opened, the heat between the heat medium heat exchanger 15a and the use side heat exchanger 26a, and the heat between the heat mediums. The heat medium circulates between the exchanger 15b and the use side heat exchangers 26b to 26d.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the first refrigerant flow switching device 11 and the check valve 13b. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-temperature and high-pressure gas refrigerant that has flowed into the heat medium relay unit 3 flows into the heat exchanger related to heat medium 15b that acts as a condenser through the second refrigerant flow switching device 18b.

The gas refrigerant flowing into the heat exchanger related to heat medium 15b becomes liquid refrigerant while dissipating heat to the heat medium circulating in the heat medium circuit B. The refrigerant flowing out of the heat exchanger related to heat medium 15b is expanded by the expansion device 16b and becomes a low-pressure two-phase refrigerant. This low-pressure two-phase refrigerant flows into the heat exchanger related to heat medium 15a acting as an evaporator via the expansion device 16a. The low-pressure two-phase refrigerant that has flowed into the heat exchanger related to heat medium 15a evaporates by absorbing heat from the heat medium circulating in the heat medium circuit B, thereby cooling the heat medium. The low-pressure two-phase refrigerant flows out of the heat exchanger related to heat medium 15a, flows out of the heat medium converter 3 through the second refrigerant flow switching device 18a, and flows into the outdoor unit 1 again.

The refrigerant that has flowed into the outdoor unit 1 passes through the check valve 13c and flows into the heat source side heat exchanger 12 that functions as an evaporator. And the refrigerant | coolant which flowed into the heat source side heat exchanger 12 absorbs heat from outdoor air in the heat source side heat exchanger 12, and becomes a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant flowing out from the heat source side heat exchanger 12 is again sucked into the compressor 10 via the first refrigerant flow switching device 11 and the accumulator 19.

At this time, the second refrigerant flow switching device 18a is in communication with the low pressure side piping, while the second refrigerant flow switching device 18b is in communication with the high pressure side piping. Further, the expansion device 16b is configured so that a subcool obtained as a difference between a value obtained by converting the pressure detected by the first pressure sensor 36 into a saturation temperature and a temperature detected by the third temperature sensor 35b is constant. The opening is controlled. Further, the expansion device 16a is fully opened, and the opening /

closing devices

17a and 17b are closed. Note that the expansion device 16b may be fully opened, and the subcooling may be controlled by the expansion device 16a.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the heating main operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in the heat exchanger related to heat medium 15b, and the heated heat medium is caused to flow in the heat medium pipe 5 by the pump 21b. Further, the cold heat of the heat source side refrigerant is transmitted to the heat medium by the heat exchanger related to heat medium 15a, and the cooled heat medium is caused to flow in the heat medium pipe 5 by the pump 21a. The heat medium pressurized and discharged by the

pumps

In the use side heat exchanger 26a, the heat medium absorbs heat from the indoor air, thereby cooling the indoor space 7. Further, in the use side heat exchangers 26b to 26d, the heat medium radiates heat to the indoor air, thereby heating the indoor space 7. At this time, the flow rate of the heat medium is controlled to a flow rate necessary to cover the air conditioning load required indoors by the action of the heat medium flow rate adjusting devices 25a to 25d, and flows into the use side heat exchangers 26a to 26d. It is like that.
The heat medium whose temperature has slightly increased after passing through the use side heat exchanger 26a flows into the heat exchanger related to heat medium 15a through the heat medium flow control device 25a and the first heat medium flow switching device 22a, and again. It is sucked into the pump 21a.
Further, the heat medium that has passed through the use side heat exchangers 26b to 26d and has been slightly lowered in temperature passes through the heat medium flow control devices 25b to 25d and the first heat medium flow switching devices 22b to 22d, and heat between the heat media. It flows into the exchanger 15b and is sucked into the pump 21b again.

During execution of the heating main operation mode, the warm heat medium and the cold heat medium are respectively mixed with the heat load without being mixed by the action of the first heat medium flow switching device 22 and the second heat medium flow switching device 23. Then, it is introduced into the use side heat exchangers 26a to 26d having a cold load.
In the heat medium pipe 5 of the use side heat exchangers 26a to 26d, the first heat medium flow is supplied from the second heat medium flow switching device 23 via the heat medium flow control device 25 on both the heating side and the cooling side. A heat medium flows in the direction to the path switching device 22.
The air conditioning load required in the indoor space 7 is the difference between the temperature detected by the first temperature sensor 31b on the heating side and the temperature detected by the second temperature sensors 34b to 34d on the cooling side. Can be covered by controlling the difference between the temperature detected by the second temperature sensor 34a and the temperature detected by the first temperature sensor 31a as a target value.

In addition, when performing the heating main operation mode, since it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) without heat load, the flow path is closed by the heat medium flow control device 25, The heat medium is prevented from flowing to the use side heat exchanger 26. In FIG. 7, a heat medium flows because all of the use side heat exchangers 26a to 26d have a heat load. However, when there is a use side heat exchanger 26 without a heat load, the corresponding heat medium flow rate adjustment is performed. The device 25 is fully closed.

Next, an operation in the case where the heat source side refrigerant leaks in the heat exchanger related to heat medium 15 of the heat medium relay unit 3 will be described.
When the heat source side refrigerant leaks in the heat exchanger related to heat medium 15, the heat source side refrigerant of the primary loop flows into the secondary loop, and thereby the pressure of the secondary loop increases. When the pressure in the secondary loop rises to a predetermined value (operating pressure), the relief valve 60 is activated, and the heat source side refrigerant mixed with the heat medium is discharged from the relief valve 60. Therefore, it is possible to suppress the pressure of the secondary loop, suppress the breakage of components used in the secondary loop due to the pressure increase, and suppress the leakage diffusion of the heat source side refrigerant.
At this time, the operating pressure of the relief valve 60 is determined from the type of the heat medium and the type of the heat source side refrigerant, and the operating pressure of the relief valve 60 is determined based on the maximum pressure of the heat medium and the maximum pressure of the heat source side refrigerant. By selecting a size of 60 and determining (adjusting) the flow rate discharged to the outside of the system, the secondary loop is kept at an appropriate pressure.
Further, the discharged heat source side refrigerant and the heat medium stay in the heat medium converter 3, and the refrigerant leakage detection device 61 detects this. At this time, by stopping the operation of the outdoor unit 1, stopping the

pumps

21a and 21b, and closing the heat medium flow control devices 25a to 25d, the leakage diffusion of the heat source side refrigerant to the indoor side can be further suppressed. it can.
Instead of detection by the refrigerant leakage detection device 61, the leakage of the heat source side refrigerant may be determined by a change in the refrigeration cycle of the primary loop, such as a decrease in the second pressure sensor 37 of the outdoor unit 1. In this case, the second pressure sensor is in charge of the refrigerant leakage detection means. Further, a heat medium pressure detecting device 62 for detecting the pressure of the secondary loop may be provided (see FIG. 3), and the leakage of the heat source side refrigerant may be detected by an increase in the pressure of the secondary loop. In this case, the heat medium pressure detection device 62 takes charge of the refrigerant leakage detection means.

1 outdoor unit, 2 indoor unit, 2a to 2d indoor unit, 3 heat medium converter, 4 refrigerant pipe, 4a first connection pipe, 4b second connection pipe, 5 heat medium pipe, 6 outdoor space, 7 indoor space, 8 Space, 9 building, 10 compressor, 11 first refrigerant flow switching device, 12 heat source side heat exchanger, 13a-13d check valve, 15 heat exchanger between heat medium, 15a, 15b heat exchanger between heat medium, 16 throttle device, 16a, 16b throttle device, 17a, 17b switchgear, 18 second refrigerant flow switching device, 18a, 18b second refrigerant flow switching device, 19 accumulator, 21 pump, 21a, 21b pump, 22nd 1 heat medium flow switching device, 22a to 22d, first heat medium flow switching device, 23, second heat medium flow switching device, 23a to 23d, second heat medium flow switching device, 2 Heat medium flow control device, 25a to 25d Heat medium flow control device, 26 User side heat exchanger, 26a to 26d User side heat exchanger, 31 First temperature sensor, 31a and 31b First temperature sensor, 34 Second temperature sensor 34a to 34d, second temperature sensor, 35, third temperature sensor, 35a to 35d, third temperature sensor, 36, first pressure sensor, 37, second pressure sensor, 38 、 third pressure sensor, 39a to 39d, intake air temperature detection device, 50 fourth temperature sensor, 52 (heat medium converter) control device, 52a (heat medium converter) computing device, 57 (outdoor unit) control device, 57a (outdoor unit) computing device, 60 relief valve, 60a relief valve, 60b relief valve, 61 refrigerant leakage detection device, 62 heat medium pressure detection device, 100 air conditioner , A heat source-side refrigerant circuit, B heat medium circulation circuit.

Claims

A heat source side refrigerant circulation circuit in which the heat source side refrigerant flow path of the compressor, the heat source side heat exchanger, the expansion device, and the heat exchanger between the heat mediums is connected in series and circulates the heat source side refrigerant;
A heat medium circulation circuit that circulates the heat medium, wherein the heat medium flow path of the pump, the use side heat exchanger, and the heat medium heat exchanger between the heat medium is piped in series,
The heat source side refrigerant circulation circuit and the heat medium circulation circuit are cascade-connected so that the heat source side refrigerant and the heat medium exchange heat in the heat exchanger between heat mediums,
A relief valve is provided in the heat medium circulation circuit,
The relief valve is
An air conditioner that operates when the heat source side refrigerant flows into the heat medium circulation circuit and discharges the heat source side refrigerant and the heat medium.
The air conditioner according to claim 1, wherein the relief valve operates when the pressure of the heat medium circulation circuit reaches a predetermined value.
The air conditioner according to claim 2, wherein the predetermined value is determined from a type of the heat source side refrigerant and a type of the heat medium.
The air conditioner according to any one of claims 1 to 3, wherein the relief valve is selected based on a maximum pressure of the heat source side refrigerant and a maximum pressure of the heat medium.
The relief valve has a Cv value such as a Cv value of a communication hole opened between the heat source side refrigerant circulation circuit and the heat medium circulation circuit, a maximum pressure of the heat source side refrigerant, and an operating pressure of the relief valve. The air conditioner according to claim 4, wherein the product is selected so as to satisfy a value obtained by dividing a product of a square root of the difference by a square root of an operating pressure of the relief valve.
Refrigerant leakage detection means for detecting that the heat source side refrigerant has leaked,
The air conditioner according to any one of claims 1 to 5, wherein when the refrigerant leakage detection means detects the leakage, the driving of the pump is stopped.
A heat medium flow control device for adjusting the flow rate of the heat medium;
Refrigerant leakage detection means for detecting that the heat source side refrigerant has leaked,
The air conditioner according to any one of claims 1 to 5, wherein when the refrigerant leak detection means detects the leak, the heat medium flow control device is closed.
The air conditioner according to claim 6 or 7, wherein the refrigerant leakage detection means is installed in or near the heat exchanger related to heat medium.
The refrigerant leakage detection means is
The air conditioner according to claim 6 or 7, wherein the leakage is detected when the pressure of the heat medium circulation circuit reaches a predetermined value.
The refrigerant leakage detection means is
The air conditioner according to claim 6 or 7, wherein the leakage is detected by a change in an operating state of the heat source side refrigerant circulation circuit.