JP7518329B2 - Air Conditioning System - Google Patents

Description

This relates to an air conditioning system, in particular an air conditioning system equipped with first to Nth air conditioning devices that condition the same indoor space of a building.

Patent document 1 (JP Patent Publication No. 2018-189290) shows an air conditioning system in which heat source units of multiple integrated air conditioners are each placed in a single space above the ceiling.

When multiple integrated air conditioning units, in which the refrigerant circuits are all housed in a single housing, are installed in the ceiling or attic space of a building, there is a risk that refrigerant leaking from one air conditioning unit will flow into the other air conditioning units via the attic space.

If the indoor space below the ceiling is divided by a partition, there is a possibility that refrigerant leaking from an air conditioning unit installed in an area other than the attic space of the room could flow down into the divided rooms with smaller floor areas.

However, no measures have been taken to address this phenomenon to date.

The air conditioning system of the first aspect includes first to Nth (N is an integer of 2 or more) air conditioning devices and a management unit. The management unit manages the first to Nth air conditioning devices. Each of the first to Nth air conditioning devices has a refrigerant circuit and one housing. The refrigerant circuit has a compressor, a radiator, an expansion valve, and an evaporator. A flammable refrigerant circulates through the refrigerant circuit. At least a portion of the housing is disposed in the attic space. The attic space is located above the indoor space of the building. The housing accommodates the refrigerant circuit. The attic space in which at least a portion of each of the housings of the first to Nth air conditioning devices is disposed is one continuous space. When a refrigerant leak is detected in at least one of the first to Nth air conditioning devices, the management unit stops operation or prohibits operation of all of the first to Nth air conditioning devices.

Here, when a refrigerant leak is detected in any of the air conditioning units, air conditioning units that are in operation will stop operating, and air conditioning units that are stopped will be prohibited from operating, and all air conditioning units will be in a stopped or prohibited state. As a result, even if refrigerant is released from the refrigerant circuit of the air conditioning unit with the refrigerant leak into the space above the ceiling and enters the housing of another air conditioning unit via the space above the ceiling, the refrigerant is prevented from flowing from that housing into the indoor space.

The air conditioning system of the second aspect is the air conditioning system of the first aspect, in which a first air flow path and a second air flow path are formed inside the housing of each of the first to Nth air conditioning devices. The first air flow path blows air drawn in from the indoor space into the indoor space through a radiator or an evaporator. The second air flow path blows air drawn in from the space above the ceiling into the space above the ceiling through an evaporator or a radiator. Each of the first to Nth air conditioning devices has a first refrigerant leak detection sensor arranged in the first air flow path and a second refrigerant leak detection sensor arranged in the second air flow path.

Here, two refrigerant leakage detection sensors are installed inside the housing. Therefore, it is possible to detect refrigerant that has leaked from the refrigerant circuit, whether it is refrigerant that is likely to flow mainly into the first air flow path leading to the indoor space, or refrigerant that is likely to flow mainly into the second air flow path leading to the space above the ceiling. This makes it possible to detect and take action against refrigerant that flows directly from the air conditioning device where the refrigerant leak has occurred into the indoor space, and refrigerant that flows from the air conditioning device where the refrigerant leak has occurred into the indoor space via the space above the ceiling and other air conditioning devices.

The air conditioning system of the third aspect is the air conditioning system of the first or second aspect, in which the first to Nth air conditioning devices each have a second fan that generates an air flow. The air flow generated by the second fan is an air flow that draws air from the space above the ceiling and blows it out into the space above the ceiling through an evaporator or radiator. When a refrigerant leak is detected in at least one of the first to Nth air conditioning devices, the management unit stops the compressors of all of the first to Nth air conditioning devices and drives the second fan of at least one of the first to Nth air conditioning devices.

Here, when a refrigerant leak is detected, at least one of the second fans is activated, so that even if refrigerant leaks into the attic space, it is stirred by the air blown into the attic space by the second fan. This prevents the refrigerant concentration in the air in the attic space from becoming locally high, and also prevents air with a high refrigerant concentration from the attic space from flowing into the indoor space via the air conditioning unit.

The air conditioning system of the fourth aspect is the air conditioning system of the second aspect, and each of the first to Nth air conditioning devices has a first fan and a second fan. The second fan draws air from the space above the ceiling and generates an air flow that is blown into the space above the ceiling through an evaporator or a radiator. The first fan draws air from the indoor space and generates an air flow that is blown into the indoor space through a radiator or an evaporator. When a refrigerant leak is detected by the first refrigerant leak detection sensor of at least one of the first to Nth air conditioning devices, the management unit drives the first fan of at least one of the first to Nth air conditioning devices.

Here, when a refrigerant leak is detected, at least one of the first fans operates, stirring the refrigerant that has leaked into the indoor space and preventing a local increase in the refrigerant concentration in the indoor space.

The air conditioning system of the fifth aspect is the air conditioning system of the second aspect, in which each of the first to Nth air conditioning devices has a first fan and a second fan. The second fan draws air from the space above the ceiling and generates an air flow that is blown into the space above the ceiling through an evaporator or a radiator. The first fan draws air from the indoor space and generates an air flow that is blown into the indoor space through a radiator or an evaporator. The management unit drives the second fan of at least one of the first to Nth air conditioning devices when a refrigerant leak is detected by the second refrigerant leak detection sensor of at least one of the first to Nth air conditioning devices.

Here, when a refrigerant leak is detected, at least one of the second fans is activated, so that even if refrigerant leaks into the attic space, it is stirred by the air blown into the attic space by the second fan. This prevents the refrigerant concentration in the air in the attic space from becoming locally high, and also prevents air with a high refrigerant concentration from flowing into the indoor space via the air conditioning unit.

FIG. 1 is a diagram showing the configuration of an air conditioning system that conditions an indoor space on the first floor of a building using three air conditioning apparatuses. Conceptual diagram of an air conditioning device. Control and management block diagram of the air conditioning system. A diagram showing the interior space after partitions have been installed. FIG. 4 is a diagram showing a control flow for checking for refrigerant leakage and taking appropriate measures.

(1) Overall Configuration Fig. 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 units 10 (a first air conditioning unit 10A, a second air conditioning unit 10B, and a third air conditioning unit 10C). Systems similar to the air conditioning system 100 are also installed in each indoor space on the second floor and above of the building 80, but here, the air conditioning system 100 installed in the indoor space S1 on the first floor will be described.

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

The air conditioning device 10 uses R32, a mildly flammable refrigerant, as a refrigerant. R32 is a refrigerant that is deemed to be "2L class" according to the US ANSI/ASHRAE34-2013 standard. If R32 leaks into the indoor space S1 and the refrigerant concentration in the room increases, there is a risk of a combustion accident occurring due to the flammability of the refrigerant. There is a demand to prevent such combustion accidents.

(2) Detailed Configuration (2-1) Air Conditioning Device The first air conditioning device 10A, the second air conditioning device 10B, and the third air conditioning device 10C shown in Fig. 1 basically have the same configuration. Therefore, in Fig. 2, these configurations will be described as the air conditioning device 10. In Fig. 2, the left side of the figure is the top and the right side of the figure is the bottom, with the right side being the indoor space S1 and the left side being the space above the ceiling 85.

Although the configuration is the same, the first air conditioning unit 10A is a 3 horsepower unit, and the second air conditioning unit 10B and the third air conditioning unit 10C are 2 horsepower units. In other words, the capacity of the first air conditioning unit 10A is greater than the capacity of each of the second air conditioning unit 10B and the third air conditioning unit 10C. Therefore, the amount of refrigerant filled in the refrigerant circuit 20 of the first air conditioning unit 10A is greater than the amount of refrigerant filled in the refrigerant circuit 20 of each of the second air conditioning unit 10B and the third air conditioning unit 10C.

As shown in FIG. 2, the air conditioning device 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 switching 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.

The housing 40 is fixed and arranged in the space CS1 above the ceiling in the building 80, suspended from a beam (not shown). The housing 40 houses the entire refrigerant circuit 20. The housing 40 also has an exposed surface 41 exposed to the indoor space S1. The exposed surface 41 has 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 in the housing 40 is generated by the supply air fan 31 and the exhaust fan 32. When the supply air fan 31 is operated, an air flow F1 is generated that 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 returns to the indoor space S1. This air flow F1 passes through the first air flow path 31a provided in the housing 40. In other words, the first air flow path 31a is an air flow path that blows air drawn in from the indoor space S1 through the utilization heat exchanger 24 into the indoor space S1. On the other hand, when the exhaust fan 32 is operated, 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 that order, and then returns to the attic space CS1 (see FIG. 2). This air flow F2 passes through the second air flow path 32a provided in the housing 40. In other words, the second air flow path 32a is an air flow path that blows air drawn in from the attic space CS1 through the heat source heat exchanger 22 into the attic space CS1.

The space CS1 above the ceiling in which the housings 40 of the first air conditioning unit 10A, the second air conditioning unit 10B, and the third air conditioning unit 10C are arranged is one continuous space, as shown in FIG. 1.

As shown in FIG. 3, the air conditioning device 10 further has a temperature sensor 92, a first refrigerant leakage detection sensor 71, and a second refrigerant leakage detection sensor 72. 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. The first refrigerant leakage detection sensor 71 is disposed near the utilization heat exchanger 24 in the first air flow path 31a, and detects that refrigerant has leaked from the refrigerant circuit 20. The second refrigerant leakage detection sensor 72 is disposed near the heat source heat exchanger 22 in the second air flow path 32a, and detects that refrigerant has leaked from the refrigerant circuit 20. The first refrigerant leakage detection sensor 71 and the second refrigerant leakage detection sensor 72 send a signal indicating a refrigerant leakage to the device control unit 11 when the detected refrigerant concentration exceeds a threshold value.

(2-2) Management Unit The management unit 90, which manages and controls the three air conditioning devices 10, is connected to the device control units 11 of each air conditioning device 10 via signal lines, as shown in FIG. 3, and manages and controls each air conditioning device 10 individually.

The management unit 90 mainly comprises a system control unit 91, a touch panel 96, and a buzzer 97.

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 a GPU. The control and arithmetic device reads a program stored in the storage device and performs predetermined image processing and arithmetic processing according to the program. Furthermore, the control and arithmetic device can write the results of calculations to the storage device and read information stored in the storage device according to 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.

The touch panel 96 is a device with a screen that has both display and input functions, and instructions can be given regarding the air conditioning device 10 by pressing the displays on the screen.

The buzzer 97 is a device that alerts people in the indoor space S1 by sound.

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 conditioning devices 10A, 10B, and 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 conditioning devices 10A, 10B, and 10C.

The system control unit 91 of the management unit 90 also sets the set temperature for cooling or heating operation for each of the first to third air conditioning devices 10A, 10B, and 10C individually. Specifically, the user is prompted to input the set temperature from 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 conditioning devices 10A, 10B, and 10C, each device control unit 11 temporarily stops the compressor 21 and other components as necessary so that the measured value is maintained within a range close to the predetermined set temperature based on the measured value and set temperature of the temperature sensor 92. 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, temporarily puts each of the first to third air conditioning devices 10A, 10B, and 10C individually into the first operation stop state. The control performed by the control unit of the air conditioning system 100, which is composed of the system control unit 91 and each device control unit 11, to temporarily put each of the first to third air conditioning units 10A, 10B, and 10C into the first operation stop state individually is so-called thermo-off control. Thermo-off control refers to an operation in which the operation of the compressor 21 and exhaust fan 32 is stopped and the supply air fan 31 is driven at the minimum rotation speed when the measurement value of the temperature sensor 92 reaches the set temperature (more precisely, a temperature shifted by 0.5°C or 1.0°C from the set temperature).

(3) Operation As described above, the three air conditioning apparatuses 10 (the first air conditioning apparatus 10A, the second air conditioning apparatus 10B, and the third air conditioning apparatus 10C) cool or heat the indoor space S1 on the first floor of the building 80.

During cooling operation, the four-way switching valve 25 is switched to the state shown by the solid lines in FIG. 2. High-temperature, high-pressure refrigerant is discharged from the compressor 21 of each air-conditioning device 10 and condenses in the heat source heat exchanger 22. The refrigerant flowing inside the heat source heat exchanger 22 exchanges heat with the air flowing around the heat source heat exchanger 22 by the 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 the air flowing around the utilization heat exchanger 24 by the 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 from the air outlet 41b to the indoor space S1 is cooled, and the indoor space S1 is cooled. The refrigerant that has become gaseous after passing through the utilization heat exchanger 24 is drawn into the compressor 21, compressed there, and discharged again toward the heat source heat exchanger 22.

As mentioned above, in cooling operation, the air conditioning unit 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 the dotted air flow F2 in Figure 2).

During heating operation, the four-way switching valve 25 is switched to the dotted line state shown in FIG. 2. High-temperature, high-pressure refrigerant is discharged from the compressor 21 of each air conditioning device 10 and condenses in the utilization heat exchanger 24. The refrigerant flowing inside the utilization heat exchanger 24 exchanges heat with the air flowing around the utilization heat exchanger 24 by 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 from the air outlet 41b to the indoor space S1 is heated, and the indoor space S1 is heated. The refrigerant that has been condensed and turned into a liquid state by the utilization heat exchanger 24 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. The refrigerant flowing inside the heat source heat exchanger 22 exchanges heat with the air flowing around the heat source heat exchanger 22 by the operation of the exhaust fan 32 (see air flow F2 in FIG. 2). The refrigerant that has become gaseous after passing through the heat source heat exchanger 22 is drawn into the compressor 21, compressed there, and discharged again toward the utilization heat exchanger 24.

As described above, in heating operation, the air conditioning unit 10 releases air whose heat has been absorbed by the refrigerant in the heat source heat exchanger 22 into the space CS1 above the ceiling (see the dotted air flow F2 in Figure 2).

(4) Amount of mildly flammable refrigerant R32 filled in each air conditioning unit (4-1)
As described above, the refrigerant circuit 20 of the air conditioning unit 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 unit 10.

In order 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 amount of refrigerant filled in the air conditioners 10 is determined using the LFL (Lower Flammability Limit; lower flammability limit or lower flammability concentration) defined in 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 different unique value.

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 conditioning device 10 and the height from the floor surface 86 of the indoor space S1 to the air outlet 41b of the air conditioning device 10 is defined as H ₀ (m);
The amount of refrigerant charged into the refrigerant circuit 20 is M (kg),
The lower flammable limit concentration of the refrigerant is LFL (kg/m ³ ),
Then, the amount of refrigerant charged, M (kg), is:
Formula 1: M<(1/SF)×LFL×A×H ₀
Meet the following.

Here, as shown in Figure 2, the intake port 41a and the exhaust port 41b of the air conditioning device 10 are both 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 Figure 1. The floor area A ( ^m2 ) of the indoor space S1 is the area of the floor surface 86 shown in Figure 1.

SF in Equation 1 is the safety factor. This safety factor SF can be selected as 1, 4, 6, etc. Here, SF = 1 is selected.

As described above, the amount of refrigerant M (kg) to be filled into the refrigerant circuit 20 of each of the three air conditioning units 10 (first air conditioning unit 10A, second air conditioning unit 10B, third air conditioning unit 10C) is determined. The amount of refrigerant filled into each refrigerant circuit 20, M (kg), satisfies formula 1, so even if all of the filled refrigerant leaks from any of the air conditioning units 10, the refrigerant concentration in the indoor space S1 will not exceed the LFL.

(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.
Formula 2: (1/SF)×LFL×A×H ₀ <ΣM

In addition, when the maximum amount of refrigerant filled in each of the first to third air conditioning devices 10A, 10B, and 10C is Mmax (kg),
Formula 3: Mmax<(1/SF)×LFL×A×H ₀
is satisfied. As in Equation 1 above, SF is a safety factor, and SF = 1 is selected. 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.

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 are charged with a smaller amount of refrigerant, as long as refrigerant leaks only from one air conditioning unit 10, the refrigerant concentration in the indoor space S1 will not exceed the LFL.

On the other hand, if a refrigerant leak were to occur from two or three air conditioning units 10 at the same time, the refrigerant concentration in the indoor space S1 would exceed the LFL. However, since the three air conditioning units 10 are separate and independent, even if a refrigerant leak occurs in one of the air conditioning units 10, it will hardly affect the other air conditioning units 10, and in fact, the possibility of the refrigerant concentration in the indoor space S1 exceeding the LFL is extremely small.

However, if refrigerant leakage occurs simultaneously from the refrigerant circuits 20 of multiple air conditioning units 10, it is possible that the refrigerant concentration in the indoor space S1 may exceed the LFL. In particular, as shown in FIG. 4, if some time has passed since the air conditioning system 100 was installed in the building 80 and started operating, and the indoor space S1 is then rearranged and new partitions 88 or the like are installed, the floor area of each divided space will change, increasing the possibility that the refrigerant concentration will exceed the LFL. In consideration of this, the air conditioning system 100 takes the following measures.

(5) Refrigerant Leak Check and Response When a Refrigerant Leak Occurs Fig. 5 shows a control flow by the system control unit 91 of the management unit 90 for checking whether refrigerant is leaking from the refrigerant circuit 20 of the air conditioning device 10 and taking various responses when a refrigerant leak occurs. The system control unit 91 performs the various responses shown in Fig. 5 in cooperation with the device control unit 11 of each air conditioning device 10.

First, in step S11, the system control unit 91 determines whether a flag for performing processing in response to a refrigerant leak is set in the event of a refrigerant leak. This flag is set as necessary in the initial settings performed when the air conditioning system 100 is installed in the building 80, or in subsequent setting changes after rearranging the indoor space S1. On a setting screen for initial settings, etc. displayed on the touch panel 96 of the management unit 90, the installer of the air conditioning system 100 or the user of the air conditioning system 100 determines whether processing in the event of a refrigerant leak is required, and selects whether to set the flag or not. In other words, the touch panel 96 of the management unit 90 serves as a selection unit for selecting whether to perform processing when a refrigerant leak is detected or not.

For example, in the air conditioning system 100 of this embodiment that satisfies the above formula 2, if the indoor space S1 is rearranged and the floor surface of the indoor space S1 is divided into a left floor surface 86a and a right floor surface 86b as shown in FIG. 4, the volume of the space above the right floor surface 86b will be smaller. Then, if a refrigerant leak occurs from the refrigerant circuit 20 of any of the air conditioning devices 10, it is expected that the refrigerant concentration in that space will exceed the LFL, so a flag is set.

On the other hand, if the indoor space S1 is not divided and the refrigerant concentration in the indoor space S1 does not exceed the LFL even if refrigerant leaks from one of the air conditioning units 10, there is no need to set the flag and the flag will be lowered.

If the flag is set in step S11, the process proceeds to step S12. In step S12, it is determined whether a refrigerant leak has been detected by the first refrigerant leak detection sensor 71 or the second refrigerant leak detection sensor 72 of any of the three air conditioning units 10. If a refrigerant leak has been detected in any of the air conditioning units 10, the system control unit 91 proceeds to step S13.

In step S13, the compressors 21 of all air conditioners 10 are stopped or prohibited from operating, including air conditioners 10 in which a refrigerant leak has been detected and air conditioners 10 in which a refrigerant leak has not been detected. Specifically, in step S13, the system control unit 91 stops the compressors 21 of air conditioners 10 that are in operation, and prohibits the compressors 21 of air conditioners 10 that are stopped from starting.

In step S14 following step S13, it is determined whether or not a refrigerant leak has been detected by the second refrigerant leak detection sensor 72 disposed in the second air flow path 32a that communicates with the attic space CS1. If a refrigerant leak has been detected by the second refrigerant leak detection sensor 72, the process proceeds to step S15, where the exhaust fans 32 of all three air conditioning units 10 are operated to agitate the air in the attic space CS1. Next, the process proceeds to step S16, where the system control unit 91 operates the supply air fan 31 of the air conditioning unit 10 in which a refrigerant leak has been detected.

On the other hand, if it is determined in step S14 that a refrigerant leak has not been detected by the second refrigerant leak detection sensor 72, the system control unit 91 proceeds to step S17. The fact that the system control unit 91 proceeds to step S17 means that a refrigerant leak has been detected in step S12, and that a refrigerant leak has not been detected by the second refrigerant leak detection sensor 72 in step S14, and therefore a refrigerant leak has been detected by the first refrigerant leak detection sensor 71.

In step S17, in view of the fact that a refrigerant leak has been detected by the first refrigerant leak detection sensor 71 disposed in the first air flow path 31a that is in direct communication with the indoor space S1, the air supply fans 31 of all three air conditioning units 10 are operated to agitate the air in the indoor space S1.

If the flag is not set in the initial step S11, no check for refrigerant leakage or response control in the event of a refrigerant leakage will be performed in steps S12 and onwards. In other words, if the installer or user chooses not to set the flag, assuming that the refrigerant concentration in the indoor space S1 will not exceed the LFL even if refrigerant leaks from any of the air conditioning devices 10, the system control unit 91 will maintain the operation continuation or operation permitted state of all of the first to third air conditioning devices 10A, 10B, 10C, regardless of whether a refrigerant leakage is detected in the air conditioning device 10.

(6) Features (6-1)
In the air conditioning system 100 of the above embodiment, when a refrigerant leak is detected in at least one of the first to third air conditioning devices 10A, 10B, and 10C, the system control unit 91 of the management unit 90 stops operation or prohibits operation of all of the first to third air conditioning devices 10A, 10B, and 10C (see step S13 in FIG. 5). In other words, when a refrigerant leak is detected in any of the air conditioning devices 10, the system control unit 91 stops operation of the air conditioning devices 10 that are in operation, prohibits operation of the air conditioning devices 10 that are stopped, and stops operation of the compressors 21 of all the air conditioning devices 10. As a result, even if the refrigerant is released from the refrigerant circuit 20 of the air conditioning device 10 in which the refrigerant leaks into the space CS1 above the ceiling and the refrigerant enters the housing 40 of another air conditioning device 10 through the space CS1 above the ceiling, the refrigerant is prevented from flowing from that housing 40 into the indoor space CS1.

The phenomenon in which refrigerant leaks from one air conditioning device 10 into the attic space CS1, enters another air conditioning device 10, and flows into the indoor space S1 can be explained by taking the first and third air conditioning devices 10A and 10C arranged as shown in FIG. 4 as an example. The refrigerant leaks from the first air conditioning device 10, flows through the attic space CS1, enters the housing 40 of the third air conditioning device 10C, and leaks from the housing 40 to the right side of the partition 88 in the indoor space S1. In particular, if the third air conditioning device 10C is an equipment that has a path for introducing outside air, it may introduce air from the attic space CS1 to the indoor space S1. Therefore, it is preferable that the first to third air conditioning devices 10A, 10B, and 10C that share the attic space CS1 perform the refrigerant leakage check and corresponding processing shown in FIG. 5 above, even if the refrigerant circuits 20 are each independent.

(6-2)
In the air conditioning system 100 of the above embodiment, two refrigerant leakage detection sensors 71, 72 are provided inside the housing 40 of each air conditioning device 10. Therefore, it is possible to detect refrigerant that has leaked from the refrigerant circuit 20, both refrigerant that is likely to flow mainly into the first air flow path 31a leading to the indoor space S1 and refrigerant that is likely to flow mainly into the second air flow path 32a leading to the attic space CS1. This makes it possible to detect and take action against refrigerant that flows directly from the air conditioning device 10 in which refrigerant leakage has occurred to the indoor space S1, and refrigerant that flows from the air conditioning device 10 in which refrigerant leakage has occurred to the indoor space S1 via the attic space CS1 and another air conditioning device 10.

(6-3)
In the air conditioning system 100 of the above embodiment, when the first refrigerant leakage detection sensor 71 detects a refrigerant leakage in at least one of the first to third air conditioning devices 10A, 10B, and 10C, the system control unit 91 of the management unit 90 drives at least one of the supply air fans 31 of the first to third air conditioning devices 10A, 10B, and 10C (see steps S17 and S18 in FIG. 5). In this way, in the air conditioning system 100, when a refrigerant leakage is detected, at least one of the supply air fans 31 operates, so that the refrigerant leaked into the indoor space S1 is agitated, and a partial increase in the refrigerant concentration in the indoor space S1 is suppressed.

(6-4)
In the air conditioning system 100 of the above embodiment, when the second refrigerant leakage detection sensor 72 of at least one of the first to third air conditioning devices 10A, 10B, and 10C detects a refrigerant leakage, the system control unit 91 of the management unit 90 stops the compressors 21 of all the first to third air conditioning devices and drives the exhaust fan 32 of at least one of the first to third air conditioning devices 10A, 10B, and 10C (see steps S13 to S15 in FIG. 5). In this way, in the air conditioning system 100, when a refrigerant leakage is detected, the exhaust fan 32 operates, so that the refrigerant is stirred even if it leaks into the space CS1 above the ceiling. Therefore, the refrigerant concentration of the air in the space CS1 above the ceiling is suppressed from being partially high, and the air in the space CS1 above the ceiling with a high refrigerant concentration is also suppressed from flowing into the indoor space S1 via the air conditioning device 10.

(7) Modifications (7-1) Modification 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 the cooling operation and the heating operation may be installed in the indoor space S1.

(7-2) Modification 1B
Although not explicitly stated in the description of the air conditioning system 100 of the above embodiment, it is preferable that when a refrigerant leak is detected in any of the air conditioning devices 10, the touch panel 96, which is responsible for the display function of the management unit 90, displays that a refrigerant leak has occurred and that measures are being taken such as stopping the operation of a specific air conditioning device 10. It is also preferable that the system control unit 91 of the management unit 90 sound a buzzer 97 to notify people in the indoor space S1 of the abnormality related to the refrigerant leak.

(7-3) Modification 1C
In the air conditioning system 100 of the above embodiment, in step S15 of Figure 5, the system control unit 91 operates the exhaust fans 32 of all air conditioning devices 10. Alternatively, it is also possible to operate only the exhaust fan 32 of the air conditioning device 10 in which a refrigerant leak has been detected.

In addition, in step S17 of FIG. 5, the system control unit 91 operates the supply air fans 31 of all air conditioning units 10, but instead, it may operate only the supply air fan 31 of the air conditioning unit 10 in which a refrigerant leak has been detected.

In addition, step S18 in FIG. 5 is not a required process and may be omitted.

(7-4) Modification 1D
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 integrated air conditioner 10 is also effective when the refrigerant circuit 20 is filled with other flammable refrigerants. The above technology is also effective when the refrigerant circuit 20 is filled with a single refrigerant of R32, R1234yf, R1234ze, or R744, which is a so-called slightly flammable refrigerant, or a mixed refrigerant containing such a refrigerant. Note that the above 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.

In addition to mildly flammable refrigerants, weakly flammable refrigerants or highly flammable refrigerants are also envisioned as the refrigerants that fill and flow through the refrigerant circuit 20. Mildly flammable refrigerants are refrigerants that are determined to be "Class 2L" according to the US ANSI/ASHRAE34-2013 standard. Mildly flammable refrigerants are refrigerants that are determined to be "Class 2" according to the US ANSI/ASHRAE34-2013 standard. Highly flammable refrigerants are refrigerants that are determined to be "Class 3" according to the US ANSI/ASHRAE34-2013 standard.

Here, the US ANSI/ASHRAE34-2013 standard is a US standard on the evaluation criteria for flammable gases. Chemical substances are regulated in countries around the world, and one of the things that is regulated is the flammability of chemical substances. Each country sets its own standards and classifies gases as flammable or not based on their respective evaluation criteria. In Japan's High Pressure Gas Safety Act, the explosion limit value is used as the criterion for judging flammable gases. Evaluation criteria for flammable gases include ASHRAE34 and DOT in the US, EN378-1 and CLP regulations in Europe, and GHS and ISO10156 in international standards. For example, the European standard equivalent to the US ANSI/ASHRAE34-2013 standard is DIN EN378-1 (2008). Here too, the same "Class 3: Highly flammable", "Class 2: Lowly flammable", and "Class 2L: Slightly flammable" are specified as in the US ANSI/ASHRAE34-2013 standard. Additionally, ISO/FDIS (Final Draft International Standard) 817 (2013) also specifies similar "Class 3: Highly flammable," "Class 2: Lowly flammable," and "Subclass 2L: Slightly flammable."

(7-5) Modification 1E
In the air conditioning system 100 of the above embodiment, the indoor space S1 is conditioned by three air conditioning apparatuses 10, but it goes without saying that the target space may be conditioned by four or more air conditioning apparatuses.

(7-6)
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 described in the claims.

10 (10A, 10B, 10C) Air conditioner 20 Refrigerant circuit 21 Compressor 22 Heat source heat exchanger (radiator or evaporator)
23 Expansion valve 24 Utilization heat exchanger (evaporator or radiator)
31 Air supply fan (first fan)
31a First air flow path 32 Exhaust fan (second fan)
32a: Second air flow path 40: Housing 71: First refrigerant leak detection sensor 72: Second refrigerant leak detection sensor 80: Building 90: Management unit (management section)
91 System control unit 100 Air conditioning system S1 Indoor space CS1 Space above the ceiling

JP 2018-189290 A

Claims (4)

First to Nth (N is an integer of 2 or more) air conditioning apparatuses (10A, 10B, 10C);
A management unit (90) that manages the first to Nth air conditioning devices;
Equipped with
Each of the first to Nth air conditioning apparatuses is
a refrigerant circuit (20) having a compressor (21), a radiator (22), an expansion valve (23) and an evaporator (24), in which a flammable refrigerant circulates;
A housing (40) at least a part of which is disposed in a ceiling space (CS1) located above an indoor space (S1) of a building and which houses the refrigerant circuit;
having
The space (CS1) above the ceiling in which at least a portion of the housing of each of the first to Nth air conditioning devices is disposed is a single continuous space,
When a refrigerant leak is detected in at least one of the first to Nth air conditioning devices, the management unit (90) stops operation or prohibits operation of all of the first to Nth air conditioning devices ,
Each of the first to Nth air conditioning devices has a second fan that draws in air from the space above the ceiling and generates an air flow that blows air into the space above the ceiling through the evaporator or the radiator,
When a refrigerant leak is detected in at least one of the first to Nth air conditioning devices, the management unit stops the compressors of all of the first to Nth air conditioning devices and drives the second fan of at least one of the first to Nth air conditioning devices. A first air flow path is formed inside the housing of each of the first to Nth air conditioning devices, which blows air sucked from the indoor space through the radiator or the evaporator into the indoor space, and a second air flow path is formed inside the housing of each of the first to Nth air conditioning devices, which blows air sucked from the space above the ceiling into the space above the ceiling through the evaporator or the radiator,
Each of the first to Nth air conditioning devices has a first refrigerant leakage detection sensor arranged in the first air flow path and a second refrigerant leakage detection sensor arranged in the second air flow path.
The air conditioning system of claim 1 . Each of the first to Nth air conditioning apparatuses is
A second fan that draws in air from the space above the ceiling and generates an air flow that blows the air into the space above the ceiling through the evaporator or the radiator;
A first fan that draws in air from the indoor space and generates an air flow that passes through the radiator or the evaporator and blows the air into the indoor space;
having
When a refrigerant leak is detected by the first refrigerant leak detection sensor of at least one of the first to Nth air conditioning devices, the management unit drives the first fan of at least one of the first to Nth air conditioning devices.
The air conditioning system according to claim 2. Each of the first to Nth air conditioning apparatuses is
A second fan that draws in air from the space above the ceiling and generates an air flow that blows the air into the space above the ceiling through the evaporator or the radiator;
A first fan that draws in air from the indoor space and generates an air flow that passes through the radiator or the evaporator and blows the air into the indoor space;
having
When a refrigerant leak is detected by the second refrigerant leak detection sensor of at least one of the first to Nth air conditioning devices, the management unit drives the second fan of at least one of the first to Nth air conditioning devices.
The air conditioning system according to claim 2.

Images