Air conditioning device and air conditioning system

Abstract

To provide an air conditioning device that eliminates the need of great expenses for safety measure such as a refrigerant shut-off valve.SOLUTION: An air conditioning device 10 includes a refrigerant circuit and single housing for accommodating it. The air conditioning device has a refrigerant filling amount M (kg) that satisfies a figure 1: M<LFL×A×H0, where A(m2) represents a floor area of an indoor space, H0(m) represents a height of a suction port and blow-out port from a floor surface of the indoor space, M(kg) represents a filling amount of refrigerant to be filled into the refrigerant circuit and LFL(kg / m3) represents a combustion lower limit concentration of the refrigerant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air conditioning device and an air conditioning system equipped with the same. [Background technology]

[0002] Patent Document 1 (JP 2017-9267 A) discloses an air conditioning system equipped with a refrigerant shutoff valve. The air conditioning system shown in Figures 8 to 10 of Patent Document 1 is a so-called multi-type air conditioning system in which multiple indoor units are connected to one outdoor unit. The refrigerant shutoff valve is a component that closes when a refrigerant leak is detected, and is provided for each indoor unit. Summary of the Invention [Problem to be solved by the invention]

[0003] In the so-called multi-type air conditioning systems described above that use flammable refrigerants, a refrigerant shut-off valve is often provided to prevent refrigerant from leaking into the outdoor unit or other indoor units when a refrigerant leak occurs in one of the indoor units.

[0004] However, implementing safety measures such as installing refrigerant shutoff valves in all indoor units would be very expensive. [Means for solving the problem]

[0005] An integrated air conditioning apparatus according to a first aspect includes a refrigerant circuit and a single housing. The refrigerant circuit has a compressor, a radiator, an expansion valve, and an evaporator. A flammable refrigerant having a density greater than that of air at atmospheric pressure circulates through the refrigerant circuit. The housing is disposed inside a building and houses the refrigerant circuit. The housing has an exposed surface. A portion of the exposed surface is exposed to the indoor space of the building. The exposed surface is formed with an intake port that draws in indoor air and an outlet port that blows the air drawn in through the intake port into the indoor space.

[0006] The floor area of ​​the indoor space is A (m 2 ), The smaller of the height from the floor of the indoor space to the intake port and the height from the floor of the indoor space to the outlet port is H0 (m). The amount of refrigerant charged into the refrigerant circuit is M (kg). The lower flammable limit of the refrigerant is defined as LFL (kg / m 3 ), When this is done, the refrigerant charge amount M (kg) is: Formula 1:M <LFL×A×H0 Meet the following.

[0007] In the air conditioner of the first aspect, an air conditioner is realized that does not require expensive safety measures such as refrigerant shut-off valves, by accommodating all refrigerant circuits in a single housing and configuring the amount of refrigerant filled into the refrigerant circuit (filling amount M) to satisfy the above formula 1. By using one or more such all-in-one air conditioners that keep the refrigerant filling amount small depending on the size of the interior of a building, it is possible to ensure comfort inside the building.

[0008] An air conditioner according to a second aspect is the air conditioner according to the first aspect, wherein the housing is placed in a space above the ceiling of a building. The space above the ceiling is a space located above the indoor space of the building.

[0009] Here, the housing of the integrated air conditioning unit is placed in the attic space, which is a relatively large space other than the indoor space within the building. This allows H0(m) in Equation 1 to be increased. As a result, the amount of refrigerant filled into each of one or more air conditioning units can be increased within the range that satisfies Equation 1. In other words, it is possible to increase the capacity of each of one or more air conditioning units. Furthermore, using the attic space makes it easy to place multiple integrated air conditioning units.

[0010] An air conditioning system according to a third aspect comprises first to Nth (N is an integer of 2 or more) air conditioning apparatuses. The first to Nth air conditioning apparatuses are each the integrated air conditioning apparatus according to the first or second aspect above. The air conditioning system according to a third aspect air-conditions an indoor space using the first to Nth air conditioning apparatuses.

[0011] The maximum amount of refrigerant charged into each of the first to Nth air conditioners is defined as Mmax (kg). The total amount of refrigerant charged into each of the first to Nth air conditioners is ΣM (kg), The floor area of ​​the indoor space is A (m 2 ), The smaller of the height from the floor of the indoor space to the intake port and the height from the floor of the indoor space to the outlet port is H0 (m). The lower flammable limit of the refrigerant is defined as LFL (kg / m 3 ), When this is done, the total amount of refrigerant charged, ΣM (kg), is: Equation 2: LFL×A×H0<ΣM Equation 3: Mmax <LFL×A×H0 Meet the following.

[0012] An air conditioning system according to a third aspect is equipped with a plurality of air conditioning apparatuses (first to Nth air conditioning apparatuses), and is able to increase the overall capacity while keeping the refrigerant charge amount of each small. In particular, the comfort of the indoor space is improved by allowing the total refrigerant charge amount ΣM of each air conditioning apparatus to exceed the lower flammability limit of the refrigerant, which is (LFL × A × H0). Meanwhile, a plurality of integrated air conditioning apparatuses are provided in the indoor space, and the charge amount Mmax (kg) of the air conditioning apparatus with the largest refrigerant charge amount among the air conditioning apparatuses satisfies Equation 3. Therefore, even if a refrigerant leak occurs in one of the air conditioning apparatuses, refrigerant combustion will not occur in the indoor space. In this way, the air conditioning system according to the third aspect improves the comfort of the indoor space while maintaining the safety of the indoor space.

[0013] An air conditioning system according to a fourth aspect is the system according to the third aspect, further comprising a control unit that controls the first to Nth air conditioners. The control unit individually switches between an operating state and a stopped state of each of the first to Nth air conditioners.

[0014] Here, the comfort of the interior space can be finely adjusted.

[0015] An air conditioning system according to a fifth aspect is the system according to the fourth aspect, wherein the control unit individually switches the cooling operation state and the heating operation state of each of the first to Nth air conditioners.

[0016] Here, the requirements regarding the air temperature at each location in the indoor space can be met.

[0017] An air conditioning system according to a sixth aspect is the system according to the fourth or fifth aspect, wherein each of the first to Nth air conditioners has a temperature sensor that measures the temperature of the air it draws in. The control unit sets the set temperature for cooling operation or heating operation for each of the first to Nth air conditioners individually. The control unit also temporarily puts each of the first to Nth air conditioners into a first operation stop state individually, based on the measurement value of the temperature sensor of each of the first to Nth air conditioners and the set temperature of each of the first to Nth air conditioners.

[0018] Here, so-called thermo-off control is performed in each air conditioner, which allows the air temperature at each location in the indoor space to be brought even closer to the set temperature.

[0019] An air conditioning system according to a seventh aspect is a system according to any one of the third aspect to the sixth aspect, wherein each of the first to Nth air conditioning apparatuses comprises: During cooling operation, the air that has absorbed heat from the refrigerant is released into the attic space above the building's indoor space. and / or During heating operation, the air that has had its heat absorbed by the refrigerant is released into the attic space located above the indoor space of the building.

[0020] Here, multiple air conditioners (1st to Nth air conditioners) share the attic space, emitting unnecessary heat to the air in the attic space and removing heat needed for heating from the air in the attic space. This eliminates the need to attach auxiliary equipment such as ducts to each air conditioner. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram showing the configuration of an air conditioning system that uses three air conditioners to condition the indoor space on the first floor of a building. [Figure 2] Conceptual diagram of an air conditioning device. [Figure 3] Control and management block diagram of the air conditioning system. DETAILED DESCRIPTION OF THE INVENTION

[0022] (1) Overall structure 1 shows an air conditioning system 100 installed in a building 80. The air conditioning system 100 is a system that cools or heats an indoor space S1 on the first floor of the building 80 using three air conditioning devices 10 (a first air conditioning device 10A, a second air conditioning device 10B, and a third air conditioning device 10C). Systems similar to the air conditioning system 100 are also installed in the indoor spaces on the second floor and above of the building 80, but here we will explain the air conditioning system 100 installed in the indoor space S1 on the first floor.

[0023] The air conditioning system 100 mainly comprises three air conditioning devices 10 and a management unit 90 that manages and controls them. As shown in Figure 1, each air conditioning device 10 is installed in the attic space CS1 on the first floor. The management unit 90 is fixed to a side wall of the indoor space S1 on the first floor.

[0024] The air conditioner 10 uses the mildly flammable refrigerant R32 as its refrigerant. R32 is a refrigerant classified as a "2L class" refrigerant according to the US ANSI / ASHRAE34-2013 standard. If R32 leaks into the indoor space S1 and the refrigerant concentration increases indoors, there is a risk of a combustion accident occurring due to the flammability of the refrigerant. Preventing this combustion accident is required.

[0025] (2) Detailed configuration (2-1) Air conditioning equipment The first air conditioner 10A, second air conditioner 10B, and third air conditioner 10C shown in Fig. 1 basically have the same configuration. Therefore, in Fig. 2, these configurations will be explained as air conditioner 10. In Fig. 2, the left side of the figure is the top and the right side is the bottom, with the ceiling 85 in between being the indoor space S1 on the right and the attic space CS1 on the left.

[0026] Although the configuration is the same, the first air conditioner 10A is a 3 horsepower device, and the second air conditioner 10B and the third air conditioner 10C are 2 horsepower devices. In other words, the capacity of the first air conditioner 10A is greater than the capacity of each of the second air conditioner 10B and the third air conditioner 10C. For this reason, the amount of refrigerant filled in the refrigerant circuit 20 of the first air conditioner 10A is greater than the amount of refrigerant filled in the refrigerant circuit 20 of each of the second air conditioner 10B and the third air conditioner 10C.

[0027] As shown in Fig. 2, the air conditioner 10 includes a refrigerant circuit 20 and a single housing 40. The refrigerant circuit 20 mainly includes a compressor 21, a heat source heat exchanger 22 that functions as a radiator or evaporator, an expansion valve 23, a utilization heat exchanger 24 that functions as an evaporator or radiator, and a four-way selector valve 25. The refrigerant circuit 20 is filled with the above-mentioned refrigerant R32. R32 is a flammable refrigerant that has a higher density than air at atmospheric pressure.

[0028] The housing 40 is fixed and disposed in a space CS1 above the ceiling in the building 80, suspended from beams (not shown). The housing 40 houses all of the refrigerant circuit 20. The housing 40 also has an exposed surface 41 exposed to the indoor space S1. The exposed surface 41 is formed with an intake port 41a that draws in air from the indoor space S1 and an outlet port 41b that blows the air drawn in from the intake port 41a into the indoor space S1. The air flow within the housing 40 is generated by the supply air fan 31 and the exhaust fan 32. When the supply air fan 31 is activated, an air flow F1 is generated, which flows from the indoor space S1 through the intake port 41a, the supply air fan 31, the utilization heat exchanger 24, and the outlet port 41b in this order, and then returns to the indoor space S1. On the other hand, when the exhaust fan 32 is activated, an air flow F2 is generated that flows from the attic space CS1 through the exhaust fan 32 and the heat source heat exchanger 22 in this order, and then returns to the attic space CS1 (see FIG. 2).

[0029] 3, the air conditioner 10 further has a temperature sensor 92. The temperature sensor 92 is a device that measures the temperature of the air in the indoor space S1 that is drawn into the housing 40.

[0030] (2-2) Management Unit The management unit 90 that manages and controls the three air conditioners 10 is connected to the device control units 11 of each air conditioner 10 by signal lines, as shown in Figure 3, and manages and controls each air conditioner 10 individually.

[0031] The management unit 90 mainly includes a system control unit 91 and a touch panel 96 .

[0032] The system control unit 91 is realized by a computer. The system control unit 91 includes a control and arithmetic device and a storage device. The control and arithmetic device can be a processor such as a CPU or GPU. The control and arithmetic device reads out a program stored in the storage device and performs predetermined image processing and arithmetic processing in accordance with the program. Furthermore, the control and arithmetic device can write the results of calculations to the storage device and read out information stored in the storage device in accordance with the program. The system control unit 91 of the management unit 90 and the device control units 11 of each air conditioning device 10 work together to form the control unit of the air conditioning system 100.

[0033] The touch panel 96 is a device having a screen that combines display and input functions, and instructions relating to the air conditioning apparatus 10 can be given by pressing the displays on the screen.

[0034] The system control unit 91 of the management unit 90 can send instruction commands to each device control unit 11. The system control unit 91 individually switches between the operating state and the stopped state of each of the first to third air conditioners 10A, 10B, 10C. The system control unit 91 also individually switches between the cooling operation state and the heating operation state of each of the first to third air conditioners 10A, 10B, 10C.

[0035] Furthermore, the system control unit 91 of the management unit 90 individually sets the set temperature for cooling or heating operation for each of the first to third air conditioners 10A, 10B, and 10C. Specifically, the user inputs the set temperature via the touch panel 96. Then, when the system control unit 91 sends set temperature information to the device control unit 11 of each of the first to third air conditioners 10A, 10B, and 10C, each device control unit 11 temporarily stops the compressor 21 and other components as necessary based on the measured value of the temperature sensor 92 and the set temperature so that the measured value is maintained within a range close to the predetermined set temperature. In other words, the control unit of the air conditioning system 100, which is made up of the system control unit 91 and each device control unit 11, individually places each of the first to third air conditioners 10A, 10B, and 10C temporarily in a first operation stop state. The control performed by the control unit of air conditioning system 100, which is made up of system control unit 91 and each device control unit 11, to temporarily place each of first to third air conditioners 10A, 10B, 10C individually into a first operation stop state is known as thermo-off control. Thermo-off control refers to operation in which, when the measurement value of temperature sensor 92 reaches the set temperature (more precisely, a temperature shifted by 0.5°C or 1.0°C from the set temperature), operation of compressor 21 and exhaust fan 32 is stopped and supply fan 31 is driven at the minimum rotation speed.

[0036] (3) Operation As described above, the three air conditioners 10 (the first air conditioner 10A, the second air conditioner 10B, and the third air conditioner 10C) cool or heat the indoor space S1 on the first floor of the building 80.

[0037] During cooling operation, the four-way selector valve 25 is switched to the state indicated by the solid lines in FIG. 2. High-temperature, high-pressure refrigerant is discharged from the compressor 21 of each air conditioner 10 and condenses in the heat-source heat exchanger 22. The refrigerant flowing inside the heat-source heat exchanger 22 exchanges heat with air flowing around the heat-source heat exchanger 22 due to operation of the exhaust fan 32 (see air flow F2 in FIG. 2). The refrigerant that has become liquid after passing through the heat-source heat exchanger 22 expands in the expansion valve 23. The low-temperature, low-pressure two-phase refrigerant decompressed by the expansion valve 23 evaporates in the utilization heat exchanger 24. The refrigerant flowing inside the utilization heat exchanger 24 exchanges heat with air flowing around the utilization heat exchanger 24 due to operation of the supply fan 31 (see air flow F1 in FIG. 2). As a result, the air taken in from the indoor space S1 and blown out into the indoor space S1 from the air outlet 41b is cooled, thereby cooling the indoor space S1. The refrigerant that has passed through the utilization heat exchanger 24 and turned into a gas state is drawn into the compressor 21, compressed in the compressor 21, and discharged again toward the heat source heat exchanger 22.

[0038] As described above, in cooling operation, the air conditioner 10 releases air that has absorbed heat from the refrigerant in the heat-source heat exchanger 22 into the space CS1 above the ceiling (see air flow F2 indicated by the dotted line in FIG. 2).

[0039] During heating operation, the four-way selector valve 25 is switched to the state indicated by the dotted lines in FIG. 2 . High-temperature, high-pressure refrigerant is discharged from the compressor 21 of each air conditioner 10 and condenses in the utilization heat exchanger 24. Heat is exchanged between the refrigerant flowing inside the utilization heat exchanger 24 and air flowing around the utilization heat exchanger 24 due to the operation of the supply air fan 31 (see air flow F1 in FIG. 2 ). As a result, the air taken in from the indoor space S1 and blown out into the indoor space S1 from the air outlet 41b is heated, heating the indoor space S1. The refrigerant that has released heat and condensed in the utilization heat exchanger 24 and is now in a liquid state expands in the expansion valve 23. The low-temperature, low-pressure two-phase refrigerant decompressed by the expansion valve 23 evaporates in the heat-source heat exchanger 22. Heat is exchanged between the refrigerant flowing inside the heat-source heat exchanger 22 and air flowing around the heat-source heat exchanger 22 due to the operation of the exhaust fan 32 (see air flow F2 in FIG. 2 ). The refrigerant that has passed through the heat source heat exchanger 22 and has become gaseous is drawn into the compressor 21, compressed in the compressor 21, and discharged again toward the utilization heat exchanger 24.

[0040] As described above, in heating operation, the air conditioner 10 releases air from which heat has been removed by the refrigerant in the heat-source heat exchanger 22 into the attic space CS1 (see air flow F2 indicated by the dotted line in FIG. 2).

[0041] (4) The amount of mildly flammable refrigerant R32 charged into each air conditioning unit (4-1) As described above, the refrigerant circuit 20 of the air conditioning device 10 is filled with a slightly flammable refrigerant, so measures must be taken to prevent a combustion accident from occurring in the indoor space S1 even if a refrigerant leak occurs from the air conditioning device 10.

[0042] To prevent a combustion accident from occurring even if refrigerant leaks from the refrigerant circuit 20 of any of the air conditioners 10 into the indoor space S1, the refrigerant charge amount of the air conditioner 10 is determined using the LFL (Lower Flammability Limit; lower flammability limit or lower flammable concentration) defined by ISO 817. The LFL is the minimum concentration of refrigerant that can propagate a flame when the refrigerant and air are mixed uniformly. The LFL is a value determined for each refrigerant. The LFL for each refrigerant, such as R32, R1234yf, and R1234ze(E), is a unique value.

[0043] The floor area of ​​the indoor space S1 where the refrigerant will remain in the event of a refrigerant leak is A (m 2 ), The smaller of the height from the floor surface 86 of the indoor space S1 to the air inlet 41a of the air conditioner 10 and the height from the floor surface 86 of the indoor space S1 to the air outlet 41b of the air conditioner 10 is defined as H0 (m), The amount of refrigerant charged into the refrigerant circuit 20 is M (kg), The lower flammable limit of the refrigerant is defined as LFL (kg / m 3 ), When this is done, the refrigerant charge amount M (kg) is: Equation 1: M<(1 / SF)×LFL×A×H0 Meet the following.

[0044] Here, as shown in FIG. 2, the air inlet 41a and the air outlet 41b of the air conditioning device 10 are at the same height as the ceiling 85 of the indoor space S1, so H0 (m) is the height distance from the floor surface 86 of the indoor space S1 to the ceiling 85 as shown in FIG. 1. The floor area A (m 2 ) is the area of ​​the floor surface 86 shown in FIG.

[0045] SF in Equation 1 is a safety factor. This safety factor SF can be selected as 1, 4, 6, etc. Here, SF=1 is selected.

[0046] As described above, the amount M (kg) of refrigerant to be filled into the refrigerant circuit 20 of each of the three air conditioners 10 (first air conditioner 10A, second air conditioner 10B, third air conditioner 10C) is determined. The amount M (kg) of refrigerant filled into each refrigerant circuit 20 satisfies Equation 1, so even if all of the refrigerant filled from any of the air conditioners 10 leaks, the refrigerant concentration in the indoor space S1 will not exceed LFL. For this reason, in the air conditioning system 100, no refrigerant leakage detection sensors are installed in either the air conditioner 10 or the indoor space S1.

[0047] (4-2) The refrigerant charge amount M (kg) of each air conditioner 10 is determined as described above. Meanwhile, the total amount ΣM (kg) of the refrigerant charge amounts M (kg) of the three air conditioners 10 is determined in the air conditioning system 100 so as to satisfy the following formula 2: Equation 2: (1 / SF)×LFL×A×H0<ΣM

[0048] Furthermore, when the maximum amount of refrigerant filled into each of the first to third air conditioners 10A, 10B, and 10C is Mmax (kg), Formula 3: Mmax<(1 / SF)×LFL×A×H0 We strive to satisfy the following.

[0049] As in Equation 1 above, SF is the safety factor, and we choose SF=1.

[0050] Here, since the amount of refrigerant filled in the refrigerant circuit 20 of the first air conditioning apparatus 10A is greater than the amount of refrigerant filled in the refrigerant circuit 20 of each of the second air conditioning apparatus 10B and the third air conditioning apparatus 10C, Mmax (kg) is the amount of refrigerant filled in the refrigerant circuit 20 of the first air conditioning apparatus 10A.

[0051] In other words, even if refrigerant leaks from the refrigerant circuit 20 of the first air conditioning unit 10A, or from the refrigerant circuit 20 of the second air conditioning unit 10B or the third air conditioning unit 10C, which have a smaller amount of refrigerant charged, as long as refrigerant leaks from only one air conditioning unit 10, the refrigerant concentration in the indoor space S1 will not exceed LFL.

[0052] On the other hand, if a refrigerant leak were to occur simultaneously from two or three air conditioners 10, the refrigerant concentration in the indoor space S1 would exceed the LFL. However, because the three air conditioners 10 are separate and independent, even if a refrigerant leak occurs in one of the air conditioners 10, it will not affect the other air conditioners 10, and the refrigerant concentration in the indoor space S1 will not actually exceed the LFL.

[0053] (5) Features (5-1) In the air conditioner 10 of the above embodiment, the refrigerant circuit 20 is entirely housed in a single housing 40, and the amount of refrigerant filled into the refrigerant circuit 20 (filling amount M) is configured to satisfy the above formula 1, thereby realizing an air conditioner that does not require expensive safety measures such as refrigerant shut-off valves. By using one or more (three in this case) of these integrated air conditioners 10, which have a small refrigerant filling amount M, depending on the size of the indoor space inside the building 80, it is possible to ensure comfort inside the building 80.

[0054] In the above embodiment, the safety factor SF=1 is selected, but if the safety factor SF=4 is selected, Equation 11: M<(1 / 4)×LFL×A×H0 The filling amount M is determined so that the safety factor SF = 6 is selected. Equation 12: M<(1 / 6)×LFL×A×H0 When a safety factor is taken into consideration, it is preferable to determine the filling amount M taking the safety factor into consideration.

[0055] (5-2) In the air conditioning apparatus 10 of the above embodiment, the housing 40 of the integrated air conditioning apparatus 10 is placed in the attic space CS1, which is a relatively large space other than the indoor space S1 within the building 80. This makes it possible to increase H0(m) in formula 1. Therefore, the amount of refrigerant filled into each of one or more air conditioning apparatuses can be increased within a range that satisfies formula 1. This makes it possible to increase the capacity of each of the three air conditioning apparatuses 10.

[0056] (5-3) The air conditioning system 100 of the above embodiment is equipped with multiple air conditioners 10 (first to third air conditioners 10A, 10B, 10C), and while keeping the refrigerant charge amount M of each small, it is possible to increase the capacity of the system as a whole. In particular, by allowing the total refrigerant charge amount ΣM of each air conditioner 10 to exceed the lower combustion limit of the refrigerant, which is (LFL × A × H0 / SF), the comfort of the indoor space S1 is improved.

[0057] On the other hand, multiple integrated air conditioners 10 are installed in the indoor space S1, and the charge amount Mmax (kg) of the first air conditioner 10A, which has the largest refrigerant charge amount among the air conditioners 10, is set to satisfy the above formula 3, so that refrigerant combustion will not occur in the indoor space S1 even if a refrigerant leak occurs in any one of the air conditioners 10. In this way, the above air conditioning system 100 improves the comfort of the indoor space S1 while maintaining the safety of the indoor space S1.

[0058] (5-4) In the air conditioning system 100 of the above embodiment, three air conditioners 10 (first to third air conditioners 10A, 10B, 10C) share the attic space CS1, emitting unnecessary heat to the air in the attic space CS1 and removing heat necessary for heating from the air in the attic space CS1. This eliminates the need to attach auxiliary equipment such as ducts to each air conditioner 10.

[0059] (6) Variations (6-1) Variation 1A The air conditioning system 100 of the above embodiment employs an air conditioning unit 10 that can switch between cooling operation and heating operation, but an air conditioning unit that performs only one of cooling operation and heating operation may also be installed in the indoor space S1.

[0060] (6-2) Variation 1B In the air conditioner 10 of the above embodiment, the refrigerant circuit 20 is filled with R32 as a refrigerant. However, the technology using the above-mentioned all-in-one air conditioner 10 is also effective when the refrigerant circuit 20 is filled with another flammable refrigerant. The above technology is also effective when the refrigerant circuit 20 is filled with a single refrigerant such as R32, R1234yf, R1234ze, or R744, which are so-called slightly flammable refrigerants, or a mixed refrigerant containing such a refrigerant. Note that R32 is difluoromethane (HFC-32), R1234yf is 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), R1234ze is 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze), and R744 is carbon dioxide.

[0061] The refrigerant that fills the refrigerant circuit 20 and flows through the refrigerant circuit 20 may be a mildly flammable refrigerant, a weakly flammable refrigerant, or a highly flammable refrigerant. A mildly flammable refrigerant is a refrigerant that is determined to be "Class 2L" according to the U.S. ANSI / ASHRAE34-2013 standard. A weakly flammable refrigerant is a refrigerant that is determined to be "Class 2" according to the U.S. ANSI / ASHRAE34-2013 standard. A highly flammable refrigerant is a refrigerant that is determined to be "Class 3" according to the U.S. ANSI / ASHRAE34-2013 standard.

[0062] The ANSI / ASHRAE 34-2013 standard is a U.S. standard for the evaluation of flammable gases. Chemical substances are regulated around the world, and one of the regulated items is their flammability. Each country establishes its own standards and classifies gases as flammable based on their own evaluation criteria. Japan's High Pressure Gas Safety Act uses the explosion limit value as the criterion for determining flammability. Evaluation standards for flammable gases include ASHRAE 34 and DOT in the U.S., EN 378-1 and CLP regulations in Europe, and GHS and ISO 10156 in international standards. European standards equivalent to the ANSI / ASHRAE 34-2013 standard include, for example, DIN EN 378-1 (2008). Similar to the ANSI / ASHRAE 34-2013 standard, this standard also specifies the following classifications: "Class 3: Highly Flammable," "Class 2: Low Flammability," and "Class 2L: Slightly Flammable." In addition, ISO / FDIS (Final Draft International Standard) 817 (2013) also specifies similar classifications: "Class 3: Highly flammable," "Class 2: Lowly flammable," and "Subclass 2L: Slightly flammable."

[0063] (6-3) Variation 1C In the air conditioning system 100 of the above embodiment, the indoor space S1 is air-conditioned by three air conditioners 10, but it goes without saying that the target space may also be air-conditioned by four or more air conditioners.

[0064] (6-4) Variation 1D In the above embodiment of the air conditioning system 100, an example was given in which the housings 40 of the three air conditioning units 10 are fixed and placed in the attic space CS1 within the building 80, but the air conditioning unit may also be a floor-standing type air conditioning unit in which the back of the housing is placed opposite the wall separating the indoors and outdoors, a so-called wall-through type air conditioning unit.

[0065] (6-5) Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0066] 10 (10A, 10B, 10C) Air conditioning equipment 11 Device control section (control section) 20 Refrigerant circuit 21 Compressor 22 Heat source heat exchanger (radiator or evaporator) 23 Expansion valve 24 Utilization heat exchanger (evaporator or radiator) 40 cabinets 41 Exposed surface 41a Intake port 41b Air outlet 80 Buildings 85 Ceiling 86 Floor 90 Management Units 91 System Control Unit (Control Unit) 100 Air Conditioning System S1 Indoor space CS1 Attic space [Prior art documents] [Patent documents]

[0067] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-9267

Claims

1. An air conditioning system (100) comprising first to Nth (N is an integer of 2 or more) air conditioning devices (10A, 10B, 10C), and air-conditioning an indoor space (S1) by the first to Nth air conditioning devices, Each of the first to Nth air conditioning devices a refrigerant circuit (20) having a compressor (21), a radiator (22), an expansion valve (23), and an evaporator (24), in which a flammable refrigerant having a density greater than that of air at atmospheric pressure circulates; a housing (40) that is arranged in an attic space (CS1) located above the indoor space (S1) of the building (80) and that houses the refrigerant circuit; An integrated air conditioning device (10) comprising: The housing has an exposed surface (41) a part of which is exposed to the indoor space of the building, The exposed surface is formed with an intake port (41a) for drawing in indoor air and an outlet port (41b) for blowing out the air drawn in from the intake port into the indoor space, The floor area of ​​the indoor space is A (m ２ ), The smaller of the height from the floor surface (86) of the indoor space to the air inlet and the height from the floor surface of the indoor space to the air outlet is defined as H ０ (m), The amount of the refrigerant charged into the refrigerant circuit is M (kg), The lower flammable limit concentration of the refrigerant is defined as LFL (kg / m ３ ), When the above formula is satisfied, the amount of refrigerant charged, M (kg), satisfies the following formula 1: Formula 1: M<LFL×A×H ０ moreover, The maximum amount of the refrigerant charged into each of the first to Nth air conditioners is Mmax (kg), The total amount of the refrigerant charged into each of the first to Nth air conditioners is ΣM (kg), The floor area of ​​the indoor space is A (m ２ ), The smaller of the height from the floor surface of the indoor space to the air inlet and the height from the floor surface of the indoor space to the air outlet is defined as H ０ (m), The lower flammable limit concentration of the refrigerant is defined as LFL (kg / m ３ ), When the total amount of the refrigerant charged, ΣM (kg), satisfies the following formulas 2 and 3: Expression 2: LFL × A × H ０ <ΣM Formula 3: Mmax<LFL×A×H ０ Air conditioning system.

2. a control unit (91, 11) that controls the first to Nth air conditioners; Furthermore, The control unit individually switches between an operating state and a stopped state of each of the first to Nth air conditioning apparatuses. The air conditioning system of claim 1 .

3. The control unit individually switches the cooling operation state and the heating operation state of each of the first to Nth air conditioning devices. The air conditioning system according to claim 2 .

4. Each of the first to Nth air conditioning devices has a temperature sensor that measures the temperature of the air that is drawn in, The control unit The set temperatures for the cooling operation or heating operation of each of the first to Nth air conditioners are individually set, individually and temporarily placing each of the first to N-th air conditioning devices in a first operation stop state based on the measurement value of the temperature sensor of each of the first to N-th air conditioning devices and the set temperature of each of the first to N-th air conditioning devices; The air conditioning system according to claim 3 .

5. Each of the first to Nth air conditioning devices is In the cooling operation, the air that has absorbed heat from the refrigerant is released into an attic space (CS1) located above the indoor space of the building. and / or In a heating operation, the air from which heat has been absorbed by the refrigerant is released into an attic space (CS1) located above the indoor space of the building.

5. An air conditioning system according to claim 1.

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