Patent Description:
Patent Literature <NUM> describes an air-conditioning apparatus that is provided with a refrigerant detection device provided at an outer surface of an indoor unit and a control unit that performs control for causing an indoor fan to rotate when the refrigerant detection device detects refrigerant. In the air-conditioning apparatus, when refrigerant leaks into a room from an extension pipe connected to the indoor unit or refrigerant leaking within the indoor unit flows out of the indoor unit through a gap in a housing of the indoor unit, the refrigerant detection device can detect the leakage refrigerant. Furthermore, when detecting leakage of the refrigerant, the refrigerant detection device causes the indoor fan to rotate, whereby air in the room is sucked from an air inlet provided in the housing of the indoor unit, air therein is blown from the air outlet into the room, and the leakage refrigerant can thus be diffused. Patent literature <NUM> describes a leaked ammonia eliminating apparatus for an ammonia refrigerating apparatus which performs air-conditioning on a ship. Leaked ammonia is removed by venting a refrigerator chamber in which a first, second and third heat exchanger are arranged. Patent Literature <NUM> describes an air conditioning system and control method to allow individual zone thermostats to directly control a variable capacity compressor and adaptively adjust the indoor supply air volume to meet zoning demands, without using static pressure or flow sensors or entering a set of pre-defined air flow values for each zone into a controller. The method controls an air conditioning system that is able to receive signals or commands from individual zone thermostats and give priority to a highest demand zone/thermostat. For example, a priority thermostat can be used to directly control the variable capacity compressor via an indoor controller and outdoor controller. Patent Literature <NUM> describes an HVAC system having an air supply system, a refrigerant circuit configured to condition air in the air supply system, and an electrochemical sensor configured to detect a refrigerant leak from the refrigerant circuit.

For example, in an air-conditioning system that air-conditions a plurality of target spaces for air-conditioning, using a single refrigerant circuit, the amount of refrigerant may be large for the volume of each of the target spaces. In such an air-conditioning system, if refrigerant leaks, and then even if the refrigerant is uniformly diffused in any one of the target spaces, the refrigerant concentration of the target space may increase.

The present invention has been made to solve the above problem, and an object of the invention is to provide an air-conditioning system and a refrigerant-amount setting method for the air-conditioning system, which can prevent an increase in the refrigerant concentration of a target space for air-conditioning, even if refrigerant leakage occurs. Solution to Problem.

An air-conditioning system of one embodiment of the present invention includes a refrigerant circuit that circulates refrigerant, a heat exchange unit that houses a load-side heat exchanger provided in the refrigerant circuit and is connected with a plurality of target spaces for air-conditioning by a plurality of air supply passages for use in supply of air that passes through the load-side heat exchanger, a refrigerant detection device that detects leakage of the refrigerant, and a plurality of opening/closing devices that are each provided in the plurality of air supply passages and opened/closed independently of each other. When the refrigerant detection device detects leakage of the refrigerant, the plurality of opening/closing devices are all opened.

A refrigerant-amount setting method for the air-conditioning system, according to another embodiment of the present invention, is a method for setting an amount of refrigerant in the air-conditioning system according to the above embodiment of the present invention. In the refrigerant-amount setting method, the amount of refrigerant enclosed in the refrigerant circuit satisfies M<LFL×V, where M [kg] is the amount of refrigerant enclosed in the refrigerant circuit, LFL [kg/m<NUM>] is a lower flammability limit that is the minimum concentration of the refrigerant for combustion, and V [m<NUM>] is the total volume of one or more of the target spaces that are connected with the heat exchange unit by one or more of the opening/closing devices that are opened when the refrigerant detection device detects leakage of the refrigerant.

According to the embodiments of the present invention, if refrigerant leakage occurs, it is possible to diffuse leakage refrigerant into target spaces for air-conditioning via opening/closing devices being in the opened state, and thereby prevent an increase in the refrigerant concentration of the target spaces.

An air-conditioning system and a refrigerant-amount setting method for the air-conditioning system, according to embodiment <NUM> of the present invention, will be described. <FIG> illustrates a schematic configuration of the air-conditioning system according to embodiment <NUM>. The air-conditioning system according to embodiment <NUM> is, for example, an indoor-air processing type air-conditioning system that processes indoor loads of three target spaces A, B and C for air-conditioning. The target spaces A, B and C are a plurality of rooms partitioned off as separate rooms. The target space A has a floor area Aa and a height Ha from a floor surface to a ceiling. The target space B has a floor area Ab and a height Hb from a floor surface to a ceiling. The target space C has a floor area Ac and has a height Hc from a floor surface to a ceiling.

As illustrated in <FIG>, the air-conditioning system according to embodiment <NUM> includes a refrigerant circuit <NUM> that circulates refrigerant. In the refrigerant circuit <NUM>, a compressor, a refrigerant flow-passage switching device (for example, a four-way valve), a heat-source-side heat exchanger, a pressure-reducing device and a load-side heat exchanger <NUM> are connected by refrigerant pipes.

As refrigerant enclosed in the refrigerant circuit <NUM>, slightly flammable refrigerant such as R1234yf and R1234ze (E) or highly flammable refrigerant such as R290 or R1270 is used. Such refrigerant may be used as a single-component refrigerant or as a mixed refrigerant in which two or more refrigerants are mixed. Hereinafter, refrigerant having flammability higher than or equivalent to a slightly flammable level (for example, <NUM> or higher in ASHRAE34 classification) may be referred to as "flammable refrigerant. " Furthermore, as the refrigerant enclosed in the refrigerant circuit <NUM>, nonflammable refrigerant having nonflammability (for example, <NUM> in ASHRAE34 classification) such as R22 or R410A can also be used. These types of refrigerant has a higher density than air under atmospheric pressure (for example, the temperature is room temperature (<NUM> degrees C).

Furthermore, the air-conditioning system includes a heat source unit <NUM> that houses at least a heat-source-side heat exchanger provided in the refrigerant circuit <NUM> and a load unit <NUM> (an example of a heat exchange unit) that houses at least a load-side heat exchanger <NUM> provided in the refrigerant circuit <NUM>. The heat source unit <NUM> and the load unit <NUM> are connected by two extension pipes 12a and 12b, which are parts of the refrigerant pipes of the refrigerant circuit <NUM>. The extension pipe 12a is connected to the load-side heat exchanger <NUM> via a joint portion 13a, and the extension pipe 12b is connected to the load-side heat exchanger <NUM> via a joint portion 13b. In embodiment <NUM>, the heat source unit <NUM> houses not only the heat-source-side heat exchanger, but the compressor, the refrigerant flow-passage switching device and the pressure-reducing device in the refrigerant circuit <NUM>. The refrigerant circuit <NUM>, the heat source unit <NUM> and the load unit <NUM> are controlled by a control unit <NUM>, which will be described later.

In the housing of the load unit <NUM>, an air inlet <NUM> and an air outlet <NUM> are provided. The air inlet <NUM> allows air to flow into the load unit <NUM>, and the air outlet <NUM> allows air to flow out of the load unit <NUM>. The space in the housing of the load unit <NUM> is partitioned into a fan chamber <NUM> and a heat exchanger chamber <NUM> by a partition plate <NUM>. An opening port is provided in the partition plate <NUM> as an air flow passage between the fan chamber <NUM> and the heat exchanger chamber <NUM>. The fan chamber <NUM> houses an fan <NUM>. The heat exchange chamber <NUM> houses the load-side heat exchanger <NUM>, the joint portions 13a and 13b, and a refrigerant detection device <NUM>.

The refrigerant detection device <NUM> detects leakage of refrigerant. As the refrigerant detection device <NUM>, for example, a semiconductor gas sensor can be used. This, however, is not limitative. The refrigerant detection device <NUM> detects the concentration of refrigerant in air and outputs a detection signal to the control unit <NUM>, which will be described later. The refrigerant detection device <NUM> is provided in the heat exchanger chamber <NUM>. This, however, is not limitative. That is, the refrigerant detection device <NUM> may be provided in the fan chamber <NUM> or may be provided outside the load unit <NUM>, for example, in an air supply duct, which will be described later. With respect to the location of the refrigerant detection device <NUM>, it suffices that the refrigerant detection device <NUM> is provided in the load unit <NUM> or in an air supply passage from the load unit <NUM> to the target space A, B or C.

In the load unit <NUM>, refrigerant may leak from brazed part of the load-side heat exchanger <NUM> and the joint portions 13a and 13b. It is therefore preferable that the load-side heat exchanger <NUM> and the joint portions 13a and 13b be provided in the housing of the load unit <NUM> (for example, in the heat exchanger chamber <NUM>) or in the air supply duct.

The control unit <NUM> includes a microcomputer provided with a CPU, a ROM, a RAM, an I/O port, a timer, etc. The control unit <NUM> is capable of mutually communicate with an operation unit <NUM>. The operation unit <NUM> allows a user to operate the operation unit <NUM>, and outputs an operation signal to the control unit <NUM> in response to the operation by the user. The operation unit <NUM> includes a plurality of remote control units each provided in an associated one of the target spaces A, B and C and a centralized controller of a higher rank than those of the plurality of remote control units.

The control unit <NUM> controls the operation of the entire air-conditioning system including the refrigerant circuit <NUM>, the heat source unit <NUM>, the load unit <NUM>, dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, etc., which will be described later, based on an operation signal from the operation unit <NUM> and detection signals from sensors or the like. The control unit <NUM> may be provided in the housing of the heat source unit <NUM> or in the housing of the load unit <NUM>. The control unit <NUM> may also include a heat-source-side control unit provided in the heat source unit <NUM> and a load-side control unit provided in the load unit <NUM> and capable of communicating with the heat-source-side control unit.

The load-side heat exchanger <NUM>, the fan <NUM>, the refrigerant detection device <NUM> and the control unit <NUM> may also be provided in the load unit <NUM> or may be assembled separately from the load unit <NUM> when being installed at the actual place.

When the fan <NUM> operates, air flows from the air inlet <NUM> toward the air outlet <NUM> in the housing of the load unit <NUM>. The air sucked from the air inlet <NUM> into the fan chamber <NUM> passes through the opening port of the partition plate <NUM> and the load-side heat exchanger <NUM> of the heat exchanger chamber <NUM> in this order. The air that passes through the load-side heat exchanger <NUM> is cooled or heated through heat exchange with the refrigerant, and blown out from the air outlet <NUM> as conditioned air.

The air outlet <NUM> of the load unit <NUM> is connected in parallel to the target spaces A, B and C by a plurality of air supply passages. The air supply passage between the air outlet <NUM> and the target space A is made up of air supply ducts <NUM>, <NUM> and <NUM>. The air supply passage between the air outlet <NUM> and the target space B is defined by the air supply ducts <NUM>, <NUM> and <NUM>. The air supply passage between the air outlet <NUM> and the target space C is defined by the air supply ducts <NUM> and <NUM>. In the case where refrigerant having a higher density than air is used, it is preferable that the air supply ducts <NUM>, <NUM> and <NUM> be provided at upper positions in the target spaces A, B and C (for example, positions close to the ceiling). When refrigerant having a smaller density than air is used, it is preferable that the air supply ducts <NUM>, <NUM> and <NUM> be provided at lower positions in the target spaces A, B and C (for example, positions close to the floor).

The air inlet <NUM> of the load unit <NUM> is connected in parallel with the target spaces A, B and C by a plurality of return passages. A return passage between the target space A and the air inlet <NUM> is defined by return ducts <NUM>, <NUM> and <NUM>. A return passage between the target space B and the air inlet <NUM> is defined by return ducts <NUM>, <NUM> and <NUM>. A return passage between the target space C and the air inlet <NUM> is defined by return ducts <NUM> and <NUM>.

The air-conditioning system includes a plurality of dampers <NUM>, <NUM> and <NUM> (examples of opening/closing devices). The damper <NUM> is provided at the air supply duct <NUM> and configured to open/close the air supply passage between the air outlet <NUM> and the target space A. The damper <NUM> is provided in the air supply duct <NUM> and configured to open/close the air supply passage between the air outlet <NUM> and the target space B. The damper <NUM> is provided in the air supply duct <NUM> and configured to open/close the air supply passage between the air outlet <NUM> and the target space C. The dampers <NUM>, <NUM> and <NUM> are opened/closed independently of each other under the control by the control unit <NUM>. For example, the damper <NUM> is opened/closed based on an operation of one of the remote control units in the concentrated controller, which is provided the target space A, the damper <NUM> is opened/closed based on an operation of one of the remote control units in the concentrated controller, which is provided in the target space B, and the damper <NUM> is opened/closed based on operation by one of the remote control units in the concentrated controller, which is provided in the target space C. The air-conditioning system according to embodiment <NUM> operates as a so-called individual operation type variable air-conditioning system in which it is possible to determine whether or not to supply conditioned air to each of the conditioned spaces A, B and C. The dampers <NUM>, <NUM> and <NUM> may also be provided at the air outlet <NUM> of the load unit <NUM>.

Furthermore, the air-conditioning system also includes a plurality of dampers <NUM>, <NUM> and <NUM>. The damper <NUM> is provided in the return duct <NUM> and configured to open/close the return passage between the target space A and the air inlet <NUM>. The damper <NUM> is provided in the return duct <NUM> and configured to open/close the return passage between the target space B and the air inlet <NUM>. The damper <NUM> is provided in the return duct <NUM> and configured to open/close the return passage between air-conditioned space C and the air inlet <NUM>. The damper <NUM> is opened/closed in conjunction with the damper <NUM> under the control by the control unit <NUM>. The damper <NUM> is opened/closed in interlock with the damper <NUM> under the control by the control unit <NUM>. The damper <NUM> is opened/closed in interlock with the damper <NUM> under the control by the control unit <NUM>. The dampers <NUM>, <NUM> and <NUM> may also be provided in the air inlet <NUM> of the load unit <NUM>.

The refrigerant detection device <NUM>, the operation unit <NUM> and the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are connected to the control unit <NUM> by control lines such that the refrigerant detection device <NUM>, the operation unit <NUM> and the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> can communicate with the control unit <NUM>. Thereby, the refrigerant detection device <NUM>, the operation unit <NUM> and the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> can share information on states of the air-conditioning system with the heat source unit <NUM> and the load unit <NUM>. Furthermore, the control unit <NUM> can acquire information from the refrigerant detection device <NUM>, the operation unit <NUM>, the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, etc., and control operations of the refrigerant detection device <NUM>, the operation unit <NUM>, the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, etc..

The control unit <NUM> can confirm that the refrigerant detection device <NUM> and the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are connected, through communication via the control lines. The control unit <NUM> does not allow the air-conditioning system (for example, the refrigerant circuit <NUM>) to operate, unless the control unit <NUM> can confirm that the control unit <NUM> are connected to the refrigerant detection device <NUM> and at least the dampers <NUM>, <NUM> and <NUM> at the air supply passage such that the control unit <NUM> can communicate with the refrigerant detection device <NUM> and at least the dampers <NUM>, <NUM> and <NUM>.

<FIG> is a flowchart of an example of a refrigerant leakage detection process that is executed by the control unit <NUM> of the air-conditioning system according to embodiment <NUM>. The refrigerant leakage detection process is repeatedly executed at predetermined time intervals only during the operation of the air-conditioning system or at all times regardless whether the air-conditioning system is in operation or in the stopped state, as long as power is supplied to the air-conditioning system. In the case where power is supplied from a power source to the air-conditioning system via a power supply switch, preferably, the power supply switch should be kept on at all times.

In step S1 in <FIG>, the control unit <NUM> acquires information on the concentration of refrigerant in the vicinity of the refrigerant detection device <NUM> based on a detection signal from the refrigerant detection device <NUM>.

Next, in step S2, the control unit <NUM> determines whether or not the concentration of refrigerant in the vicinity of the refrigerant detection device <NUM> is higher than or equal to a predetermined threshold. When the control unit <NUM> determines that the concentration of refrigerant is higher than or equal to the threshold, the process proceeds to step S3, and when the control unit <NUM> determines that the concentration of refrigerant is less than the threshold, the process ends.

In step S3, the control unit <NUM> causes the fan <NUM> to operate. That is, when the fan <NUM> is operated, the control unit <NUM> keeps the fan <NUM> operated, and when the fan <NUM> is in the stopped, the control unit <NUM> causes the fan <NUM> to start to operate. It is preferable that an operation rotation speed of the fan <NUM> (that is, the amount of air from the fan <NUM>) be set to the maximum. Furthermore, in step S3, the control unit <NUM> causes all the dampers <NUM>, <NUM> and <NUM> provided at least at the air supply passage to open. That is, the control unit <NUM> causes a closed one or ones of the dampers <NUM>, <NUM> and <NUM> to be opened, and keeps an opened or opened ones of the dampers <NUM>, <NUM> and <NUM> opened. Therefore, the dampers <NUM>, <NUM> and <NUM> provided at the air supply passage are all opened. As a result, the dampers <NUM>, <NUM> and <NUM> provided at the return passage are also all opened in interlock with the dampers <NUM>, <NUM> and <NUM>. In step S3, the control unit <NUM> may notify the user of the leakage of refrigerant using a display unit or a speech output unit provided in the operation unit <NUM>.

As described above, in the refrigerant leakage detection process, when refrigerant leakage is detected (that is, when the concentration of refrigerant detected by the refrigerant detection device <NUM> is higher than or equal to the threshold), the operation of the fan <NUM> is started and the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are all opened. Thereby, refrigerant leaking in the load unit <NUM>, along with air blown by the fan <NUM>, is blown into all the target spaces A, B and C via the air supply passages. Therefore, even when refrigerant leaks while conditioned air is being supplied to only one or more of the target spaces A, B and C, the leakage refrigerant can be diffused into all the target spaces A, B and C, thereby preventing an increase in the concentration of refrigerant only in the one or more target spaces.

It should be noted that in the case where refrigerant having a greater density than air under atmospheric pressure is used and the load unit <NUM> is provided above the target spaces A, B and C, when refrigerant leakage is detected, it is not indispensable to operate the fan <NUM>. For example, in the case where refrigerant leaks in the load unit <NUM> while the fan <NUM> is in the stopped state, the leakage refrigerant can be made, by opening all the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, to flow downwards from the load unit <NUM> into all the target spaces A, B and C via the air supply passages or the return passages. Therefore, the leakage refrigerant can be diffused into all the target spaces A, B and C, thereby preventing an increase in the concentration of refrigerant only in the one or more target spaces. The same is true of the case where refrigerant having a density smaller than the air under atmospheric pressure is used and the load unit <NUM> is provided below the target spaces A, B and C.

In the case where flammable refrigerant is used as the refrigerant, the amount of refrigerant is set to satisfy M<LFL×Σ(Ak×Hk) (k = a to c), where M [kg] is the amount of refrigerant, Aa×Ha [m<NUM>] is the volume of the target space A, Ab×Hb [m<NUM>] is the volume of the target space B, Ac×Hc [m<NUM>] is the volume of the target space C, and LFL [kg/m<NUM>] is a lower flammability limit that is the minimum concentration of the refrigerant for combustion. That is, the amount M [kg] of the refrigerant is set to satisfy the relationship "M<LFL×V", where V [m<NUM>] is the total volume of all the target spaces that are air-conditioned by the air-conditioning system. For example, as the heat source unit <NUM> and the load unit <NUM>, a given type of heat source unit and a given type of load unit that satisfy the above relationship are selected. Furthermore, in accordance with the positional relationship between the heat source unit <NUM> and the load unit <NUM>, lengths of the extension pipes 12a and 12b may be increased, thereby necessitating addition of further refrigerant. In this case, it is preferable that the amount M satisfy the above relationship after further refrigerant is added.

According to embodiment <NUM>, the leakage refrigerant can be diffused into all the target spaces A, B and C, and it is therefore possible to prevent the concentration of the refrigerant in the target spaces A, B and C from exceeding the flammability limit, by setting the amount M to a value satisfying the above relationship.

<FIG> illustrates a schematic configuration of an air-conditioning system according to a first modification of embodiment <NUM>. As illustrated in <FIG>, the air-conditioning system according to the first modification is an outdoor-air processing type air-conditioning system that processes an outside-air load. In the air-conditioning system of the first modification, none of dampers <NUM>, <NUM> and <NUM> in the return passage is provided. In this regard, the air-conditioning system of the first modification is different from the air-conditioning system as illustrated in <FIG>. Outside air is introduced into the air inlet <NUM> of the load unit <NUM>. The other configuration is the same as or similar to that of the air-conditioning system as illustrated in <FIG>. Also, in the first modification, it is possible to obtain the same advantages as in the air-conditioning system as illustrated in <FIG>.

<FIG> illustrates a schematic configuration of an air-conditioning system according to a second modification of embodiment <NUM>. As illustrated in <FIG>, the air-conditioning system according to the second modification includes an air supply passage that introduces outside air from an outside air inlet <NUM> using the fan <NUM> and supplies the outside air into the target spaces A, B and C, and an exhaust passage that exhausts air from the target spaces A, B and C to the outside using a fan <NUM>. The load unit <NUM> includes a total heat exchanger <NUM> that transfers sensible heat and latent heat between the outside air introduced into the air supply passage and return air passing through the exhaust passage. The return air that passes through the total heat exchanger <NUM> is completely exhausted to the outside through an exhaust port <NUM>. By contrast, the outside air that passes through the total heat exchanger <NUM> is further subjected to heat exchange with the refrigerant in the load-side heat exchanger <NUM>, and then supplied to the target spaces A, B and C. It should be noted that the load unit <NUM> may also be provided with a sensible heat exchanger instead of the total heat exchanger <NUM>.

In the configuration of the second modification, when refrigerant leakage occurs, it suffices that of the dampers <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, only the dampers <NUM>, <NUM> and <NUM> at the air supply passage at which the load-side heat exchanger <NUM> is provided are opened. Therefore, it suffices that the dampers <NUM>, <NUM> and <NUM> can communicable with the control unit <NUM>. It should be noted that the dampers <NUM>, <NUM> and <NUM> at the exhaust passage may also be capable of communicating with the control unit <NUM>. In the case where the dampers <NUM>, <NUM> and <NUM> are opened when refrigerant leakage occurs, the leakage refrigerant in the load unit <NUM> is not only diffused into the target spaces A, B and C, but exhausted to the outside via the exhaust passage. It is therefore possible to further reduce the concentration of refrigerant in the target spaces A, B and C. Furthermore, the dampers <NUM>, <NUM> and <NUM> may also be configured to open/close in interlock with the dampers <NUM>, <NUM> and <NUM>, respectively.

<FIG> illustrates a schematic configuration of an air-conditioning system according to a third modification of embodiment <NUM>. As illustrated in <FIG>, the air-conditioning system according to the third modification includes a plurality of heat source units <NUM> connected in parallel with a single refrigerant circuit <NUM> and a single load unit <NUM>. Also, in the third modification, it is also possible to obtain the same advantages as in the air-conditioning system as illustrated in <FIG>.

<FIG> illustrates a schematic configuration of an air-conditioning system according to a fourth modification of embodiment <NUM>. As illustrated in <FIG>, the air-conditioning system according to the fourth modification includes a plurality of sets of refrigerant circuits <NUM>, load units <NUM> and heat source units <NUM>. The air supply passages and the return passages are connected in parallel to the plurality of load units <NUM>. In the third modification, it is possible to obtain the same advantages as in the air-conditioning system as illustrated in <FIG>.

As described above, the air-conditioning system according to embodiment <NUM> includes the refrigerant circuit <NUM> that circulates refrigerant, the load unit <NUM> (an example of the heat exchange unit) that houses the load-side heat exchanger <NUM> of the refrigerant circuit <NUM> and is connected with the plurality of air-conditioned spaces A, B and C by a plurality of air supply passages for use in supply of air that passes through the load-side heat exchanger <NUM>, the refrigerant detection device <NUM> that detects leakage of refrigerant, and the plurality of dampers <NUM>, <NUM> and <NUM> (an example of the opening/closing device) that are each provided in an associated one of the plurality of air supply passages, are opened/closed independently of each other, and are all opened when the refrigerant detection device <NUM> detects leakage of refrigerant.

In the above configuration, it is possible to diffuse leakage refrigerant to all the target spaces A, B and C, and thus prevent an increase in the refrigerant concentration only in one or more of the target spaces.

Furthermore, the air-conditioning system according to embodiment <NUM> further includes fans <NUM>, which are operated when the refrigerant detection device <NUM> detects leakage of refrigerant. In this configuration, it is possible to more reliably cause the leakage refrigerant to be diffused into the target spaces A, B and C.

The air-conditioning system according to embodiment <NUM> further includes the control unit <NUM> that controls the refrigerant circuit <NUM>. The control unit <NUM> does not allow the refrigerant circuit <NUM> to be operated, unless the control unit <NUM> is connected to the refrigerant detection device <NUM> and the plurality of dampers <NUM>, <NUM> and <NUM> such that the control unit <NUM> can communicate with the refrigerant detection device <NUM> and the dampers <NUM>, <NUM> and <NUM>. In this configuration also, it is possible to further improve the safety of the air-conditioning system.

In the air-conditioning system according to embodiment <NUM>, the refrigerant may be flammable refrigerant.

In the air-conditioning system according to embodiment <NUM>, the relationship "M<LFL×V" is satisfied, where M [kg] is the amount of the refrigerant in the refrigerant circuit <NUM>, LFL [kg/m<NUM>] is the lower flammability limit of the refrigerant that is the minimum concentration of the refrigerant for combustion, and V [m<NUM>] is the total volume of one or more of the target spaces (for example, all the plurality of target spaces A, B and C) connected with the load unit <NUM> via one or more of the dampers (for example, all the plurality of dampers <NUM>, <NUM> and <NUM>) which are opened when the refrigerant detection device <NUM> detects leakage of the refrigerant. In this configuration, it is possible to prevent the refrigeration concentration of the target spaces A, B and C from exceeding the lower flammability limit.

The refrigerant-amount setting method for the air-conditioning system according to embodiment <NUM> is a method for setting the amount of refrigerant in the air-conditioning system. To be more specific, in the refrigerant-amount setting method, the amount of refrigerant enclosed in the refrigerant circuit <NUM> is set such that M<LFL×V is satisfied, where M [kg] is the amount of the refrigerant in the refrigerant circuit <NUM>, LFL [kg/m<NUM>] is the lower flammability limit of the refrigerant that is the minimum concentration of the refrigerant for combustion, and V [m<NUM>] is the total volume of one or more of the target spaces (for example, all the plurality of target spaces A, B and C) connected with the load unit <NUM> via one or more of the dampers (for example, all the plurality of dampers <NUM>, <NUM> and <NUM>) that are opened when the refrigerant detection device <NUM> detects leakage of the refrigerant. In this configuration, it is possible to prevent generation of flammable concentration areas in the target spaces A, B and C. it is possible to prevent the refrigeration concentration of the target spaces A, B and C from exceeding the lower flammability limit.

An air-conditioning system and a refrigerant-amount setting method therefor according to embodiment <NUM> of the present invention will be described. The air-conditioning system according to embodiment <NUM> includes a setting device that is operated by a technician for installation to determine in advance one or more of dampers <NUM>, <NUM> and <NUM> that are to be opened when refrigerant leakage occurs. As the setting device, for example, the operation unit <NUM> is used. As the damper or dampers that are to be opened when refrigerant leakage occurs, at least one damper is selected from among all the dampers <NUM>, <NUM> and <NUM> provided at the air supply passage. Identification information on the damper or dampers determined to be opened when refrigerant leakage occurs is stored in a ROM (for example, flash memory) in the control unit <NUM>.

The damper or dampers that are to be opened when refrigerant leakage occurs are determined in consideration of the volume of a target space or spaces that communicate with the load unit <NUM> via the damper or dampers. In the case where flammable refrigerant is used as the refrigerant, the amount of enclosed refrigerant satisfies M<LFL×V, where M [m<NUM>] is the amount of the enclosed refrigerant, V [m<NUM>] is the total volume of the target space or spaces that communicate with the load unit <NUM> via one or more of the dampers <NUM>, <NUM> and <NUM> that are opened when refrigerant leakage occurs, and LFL [kg/m<NUM>] is the lower flammability limit that is the minimum concentration of the refrigerant for combustion. In other words, of the dampers <NUM>, <NUM> and <NUM>, the damper or dampers that are to be opened when refrigerant leakage occurs are determined at the time of, for example, installing the air-conditioning system, in such a manner as to satisfy the above relationship.

<FIG> is a flowchart of an example of a refrigerant leakage detection process that is executed by the control unit <NUM> of the air-conditioning system according to embodiment <NUM>. The refrigerant leakage detection process is repeatedly executed at predetermined time intervals only during the operation of the air-conditioning system or at all times regardless whether the air-conditioning system is in operation or in the stopped state, as long as power is supplied to the air-conditioning system. Steps S11 S12 are the same as steps S1 and S2 indicated in <FIG>.

In step S12, when it is determined that the concentration of refrigerant is higher than or equal to the threshold, the process proceeds to step S13. In step S13, the control unit <NUM> acquires from the ROM the identification information on the damper or dampers determined to be opened when refrigerant leakage occurs.

In step S14, the control unit <NUM> causes the fan <NUM> to operate. That is, when the fan <NUM> is already operated, the control unit <NUM> keeps the fan <NUM> operated, and when the fan <NUM> is in the stopped state, the control unit <NUM> causes the fan <NUM> to start to operate. Furthermore, in step S14, the control unit <NUM> opens the damper or dampers determined to be opened when refrigerant leakage occurs. To be more specific, the control unit <NUM> opens a closed one or ones of the damper or dampers determined to be opened when refrigerant leakage occurs, and keeps an opened one or ones of the above damper or dampers opened. Thereby, of the dampers <NUM>, <NUM> and <NUM>, the damper or dampers determined to be opened when refrigerant leakage occurs are all opened. Also, one or more of the dampers <NUM>, <NUM> and <NUM> or all the dampers <NUM>, <NUM> and <NUM> are opened as occasion needs.

As described above, in this refrigerant leakage detection process, when refrigerant leakage is detected, the fan <NUM> is started to operate and a predetermined one or ones of the dampers <NUM>, <NUM> and <NUM> are opened. Thereby, the leakage refrigerant in the load unit <NUM> together with air blown by the fan <NUM> is blown into at least one target space via the opened damper or dampers. Therefore, even if refrigerant leakage occurs while conditioned air is being supplied only to a target space having a small volume, the leakage refrigerant can be diffused into at least one target space having a necessary total volume, thereby preventing an increase in the concentration of refrigerant only in a target space having a small volume.

As described above, the air-conditioning system according to embodiment <NUM> includes the refrigerant circuit <NUM> that circulates refrigerant, the load unit <NUM> (an example of the heat exchange unit) that houses the load-side heat exchanger <NUM> of the refrigerant circuit <NUM> and is connected with the plurality of target spaces A, B and C by the plurality of air supply passages for use in the supply of air passing through the load-side heat exchanger <NUM>, the refrigerant detection device <NUM> that detects leakage of the refrigerant, a plurality of dampers <NUM>, <NUM> and <NUM> (an example of the opening/closing devices) that are each provided at an associated one of the plurality of air supply passages and opened/closed independently of each other, and the setting device (for example, the operation unit <NUM>) that determines one or more of the plurality of dampers <NUM>, <NUM> and <NUM> that are to be opened when the refrigerant detection device <NUM> detects leakage of the refrigerant. The damper or dampers determined by the setting device are opened when the refrigerant detection device <NUM> detects leakage of the refrigerant.

In this configuration, it is possible to cause leakage refrigerant to be diffused into at least one target space having a necessary total volume and thereby prevent an increase only in the concentration of refrigerant in a target space having a small volume.

In the air-conditioning system according to embodiment <NUM>, the amount of the refrigerant enclosed in the refrigerant circuit <NUM> satisfies M<LFL×V, where M [kg] is the amount of the refrigerant enclosed in the refrigerant circuit <NUM>, LFL [kg/m<NUM>] is the lower flammability limit that is the minimum concentration of the refrigerant for combustion, and V [m<NUM>] is the total volume of a target space or target spaces connected with the load unit <NUM> via the damper or dampers (for example, damper or dampers determined by the setting device) that are opened when the refrigerant detection device <NUM> detects refrigerant leakage. In this configuration, it is possible to prevent the refrigeration concentration of the target space or target spaces from exceeding the lower flammability limit.

The refrigerant-amount setting method for the air-conditioning system according to embodiment <NUM> is a method for setting the amount of refrigerant in the air-conditioning system. In the refrigerant-amount setting method, the amount of refrigerant enclosed in the refrigerant circuit <NUM> is set such that M<LFL×V is satisfied, M [kg] is the amount of the refrigerant enclosed in the refrigerant circuit <NUM>, LFL [kg/m<NUM>] is the lower flammability limit that is the minimum concentration of the refrigerant for combustion, and V [m<NUM>] is the total volume of the target space or spaces connected with the load unit <NUM> via the damper or dampers (for example, dampers determined by the setting device) that are opened when the refrigerant detection device <NUM> detects refrigerant leakage. In this configuration, it is possible to prevent the refrigeration concentration in the target space or target spaces from exceeding the lower flammability limit.

For example, although with respect to each of the above embodiments, an air-conditioning system intended for air-conditioning for people is described above by way of example, the air-conditioning system of the present invention also covers air-conditioning systems intended for air-conditioning for objects, such as refrigeration warehouses or cold storages.

The above embodiments can be put to practical use in combination.

Claim 1:
An air-conditioning system comprising:
a refrigerant circuit (<NUM>) configured to circulate refrigerant;
a heat exchange unit configured to house a load-side heat exchanger (<NUM>) provided in the refrigerant circuit (<NUM>), the heat exchange unit being connected with a plurality of target spaces (A, B, C) for air-conditioning by a plurality of air supply passages for use in supply of air that passes through the load-side heat exchanger (<NUM>);
a plurality of opening/closing devices each provided in an associated one of the plurality of air supply passages, the plurality of opening/closing devices being configured to operate to be opened/closed independently of each other,
characterized in that
the air conditioning system further comprises a refrigerant detection device (<NUM>) configured to detect leakage of the refrigerant; and the air-conditioning system is configured such that
the plurality of opening/closing devices are all opened when the refrigerant detection device (<NUM>) detects leakage of the refrigerant.