JP7433508B2 - Leakage determination device and leakage determination system - Google Patents

Description

The present disclosure relates to a leakage determination device and a leakage determination system used in an airtight test of a refrigeration cycle device.

When installing or repairing refrigeration cycle equipment such as air conditioners, when sealing refrigerant into the refrigeration cycle equipment, it is necessary to check the airtightness of the refrigeration cycle equipment before filling to avoid refrigerant leakage. . The airtightness of the refrigeration cycle device is confirmed by an airtightness test such as a nitrogen pressurized leak test. In the nitrogen pressurization leak test, the refrigeration cycle device is filled with nitrogen gas and pressurized before the refrigerant is filled in, and airtightness is evaluated based on whether there is a pressure drop over a certain period of time.

In a conventional pressurized leak test, the pressure of the refrigeration cycle device is detected by a pressure gauge, and the presence or absence of a pressure drop is determined. When using a pressure gauge, the measurement range of the pressure gauge depends on the applied pressure, so the measurement range becomes large and the responsiveness to pressure changes becomes poor. Therefore, after the refrigeration cycle device is filled with nitrogen gas and pressurized, a long time, such as one day, is required until the airtightness is evaluated.

A differential pressure gauge method using a differential pressure gauge is also known as a method for evaluating airtightness. The differential pressure gauge method is a method in which an object to be inspected, such as a refrigeration cycle device, and a reference object called a master are simultaneously pressurized, and pressure changes due to leaks in the object to be inspected are detected as a difference between the pressure of the master and the object to be inspected. When using a differential pressure gauge, the measurement range of the differential pressure gauge does not depend on the applied pressure, so the measurement range can be made small. Therefore, responsiveness can be improved compared to the case where a pressure gauge is used.

However, since pressure fluctuates due to changes in temperature, there is a problem in performing an airtightness test using the differential pressure gauge method in that it is affected by changes in temperature. In particular, in an air conditioner as a refrigeration cycle device, the outdoor unit is often installed outdoors. Therefore, when testing is carried out in a place where the temperature changes due to solar radiation, such as outdoors, it is difficult to determine whether the fluctuation in the memory of the differential pressure gauge is due to temperature changes or leakage from the test object. Become.

In order to solve this problem, in Patent Document 1, during a leakage test, temperature correction is performed for the differential pressure between the measurement target container, which is the object to be inspected, and the reference container, which is the reference object, to prevent leakage in the measurement target container. It has been proposed to improve the determination accuracy.

Japanese Patent Application Publication No. 2007-327849

When performing an airtightness test on an air conditioner, an outdoor unit installed outdoors is often filled with nitrogen gas for pressurization. Furthermore, the temperature of the air conditioner itself increases due to the temperature increase in each part of the refrigerant circuit. In this case, the outdoor unit of the air conditioner is affected by temperature changes due to heat conduction in various parts of the refrigerant circuit, in addition to radiant heat due to sunlight.

However, in the leakage test described in Patent Document 1, the pressure is corrected based on the ambient temperature, but the influence of heat conduction and heat radiation due to the outside air temperature is not taken into account. Therefore, pressure correction is not performed appropriately, resulting in measurement errors.

The present disclosure has been made in view of the problems in the conventional technology described above, and provides a leakage determination device and a leakage determination system that can accurately determine the presence or absence of leakage in a refrigeration cycle device during an airtightness test. The purpose is to

A leakage determination device of the present disclosure is a leakage determination device that determines whether or not there is a leakage of fluid in a refrigeration cycle device in which piping forming a heat medium circulation circuit is filled with fluid. a temperature input section into which the temperature of the fluid or the outside air temperature inside the refrigeration cycle device is input; a pressure input section into which the pressure of the fluid when the pipe is filled with a set amount; a differential pressure input section into which a measured differential pressure value, which is the difference between the fluid pressure and a reference pressure, is input; a temperature of the fluid or the outside air temperature input into the temperature input section; and an input into the pressure input section. an information acquisition unit that acquires the pressure of the fluid and the actually measured differential pressure value input to the differential pressure input unit; a first temperature value that is the temperature of a pressure correction unit that calculates a temperature-corrected pressure value that is an estimated pressure at the second time point based on a second temperature value that is the temperature of the fluid or the outside air temperature; and the first pressure value and the temperature-corrected pressure value. and a calculation unit that calculates an estimated differential pressure value that is a difference between the measured differential pressure value and the estimated differential pressure value, and determines whether or not there is a leakage of the fluid in the refrigeration cycle device based on the pressure difference that is the difference between the measured differential pressure value and the estimated differential pressure value. The leakage determining unit is equipped with a leakage determination unit.

The leakage determination system of the present disclosure is a leakage determination system that determines whether or not there is a leak of fluid in a refrigeration cycle apparatus in which piping forming a heat medium circulation circuit is filled with fluid, the system comprising: A filling cylinder filled with a fluid to be filled, a master container filled with a fluid at a reference pressure that is a reference for the pressure of the fluid, and a difference between the pressure of the fluid in the piping of the refrigeration cycle device and the reference pressure. The leakage determination device includes a differential pressure gauge that measures a measured differential pressure value that is a difference, and a leakage determination device that determines whether or not there is a leakage of the fluid in the refrigeration cycle device, and the leakage determination device a temperature input section into which the temperature or outside air temperature in the refrigeration cycle device is input; a pressure input section into which the pressure of the fluid when the piping is filled with a set amount; and the actual measured differential pressure value. the temperature of the fluid or the outside air temperature input to the temperature input section, the pressure of the fluid input to the pressure input section, and the pressure input to the differential pressure input section. a first temperature value that is the temperature of the fluid or the outside air temperature at a first point in time when the pipe is filled with a set amount of the fluid; Based on a first pressure value that is the pressure in the pipe at a time point 1, and a second temperature value that is the temperature of the fluid or the outside air temperature at a second time point when a set time has elapsed from the first time point. , a pressure correction unit that calculates a temperature-corrected pressure value that is the estimated pressure at the second time point, and a calculation unit that calculates an estimated differential pressure value that is the difference between the first pressure value and the temperature-corrected pressure value; The apparatus further includes a leak determination section that determines whether or not there is a leak of the fluid in the refrigeration cycle apparatus based on a pressure difference that is a difference between the measured differential pressure value and the estimated differential pressure value.

According to the present disclosure, the presence or absence of fluid leakage in the refrigeration cycle device is determined by comparing the calculated estimated differential pressure value with the actually measured differential pressure value, which is the actual differential pressure. Therefore, it is possible to accurately determine the presence or absence of fluid leakage in the refrigeration cycle device.

1 is a block diagram showing an example of a schematic configuration of a leakage determination system according to a first embodiment; FIG. 1 is a schematic diagram showing an example of the configuration of a leakage determination device according to Embodiment 1. FIG. 1 is a schematic diagram showing an example of a configuration of a leakage determination system according to a first embodiment; FIG. FIG. 3 is a functional block diagram showing an example of the configuration of a control section in FIG. 2. FIG. FIG. 5 is a hardware configuration diagram showing an example of the configuration of a control section in FIG. 4. FIG. 5 is a hardware configuration diagram showing another example of the configuration of the control unit in FIG. 4. FIG. 2 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to the first embodiment. 2 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to the first embodiment. FIG. 2 is a schematic diagram showing an example of the configuration of a leakage determination system according to a second embodiment. FIG. 2 is a schematic diagram showing an example of the configuration of a leakage determination device according to a second embodiment. 7 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to Embodiment 2. FIG. 7 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to Embodiment 2. FIG. FIG. 3 is a schematic diagram showing an example of a configuration of a leakage determination system according to a third embodiment. 12 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to Embodiment 3. 12 is a flowchart illustrating an example of the flow of leakage determination processing by the leakage determination device according to Embodiment 3.

Embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the following embodiments, and can be variously modified without departing from the gist of the present disclosure. Further, the present disclosure includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. Further, the illustration of the specific structure of each part may be simplified or omitted as appropriate.

Embodiment 1.
A leakage determination device according to the first embodiment will be described. The leakage determination device according to the first embodiment determines the presence or absence of leakage in piping in which a heat medium such as refrigerant of the refrigeration cycle equipment circulates when an airtightness test is performed on the refrigeration cycle equipment that is the object to be inspected. It is something to do.

[Schematic configuration of leakage determination system 100]
FIG. 1 is a block diagram showing an example of a schematic configuration of a leakage determination system according to the first embodiment. As shown in FIG. 1, the leakage determination system 100 includes a leakage determination device 1, a refrigeration cycle device 2, a filling cylinder 3, a master container 4, and a differential pressure gauge 5.

The leak determination device 1 determines whether there is a leak in the refrigeration cycle device 2 during an airtight test. A refrigeration cycle device 2 and a differential pressure gauge 5 are connected to the leakage determination device 1 .

The refrigeration cycle device 2 is a measurement target on which an airtightness test is performed, and is, for example, an air conditioner that conditions the air in a space to be conditioned by circulating a refrigerant or a heat medium such as water or brine in piping. It is. A leakage determination device 1 and a filling cylinder 3 are connected to the refrigeration cycle device 2 . In addition, in the following description, the refrigerant|coolant or heat medium which circulates in the piping of the refrigeration cycle apparatus 2 is simply called a "heat medium", and is demonstrated.

The filling cylinder 3 is provided for filling and sealing the refrigeration cycle device 2 with a fluid such as nitrogen. The filling cylinder 3 is connected to the refrigeration cycle device 2. The master container 4 is a reference container filled with a fluid at a reference pressure, which serves as a pressure reference when determining leakage in the refrigeration cycle device 2 . The reference pressure is a pressure equivalent to the pressure inside the piping when the piping of the refrigeration cycle device 2 is filled with a set amount of fluid during the airtightness test. Master container 4 is connected to differential pressure gauge 5.

The differential pressure gauge 5 measures the differential pressure between the pressure of the fluid filled in the refrigeration cycle device 2 and the pressure of the fluid in the master container 4. A leak determination device 1 , a refrigeration cycle device 2 , and a master container 4 are connected to the differential pressure gauge 5 .

(Leakage determination device 1)
FIG. 2 is a schematic diagram showing an example of the configuration of the leakage determination device according to the first embodiment. As shown in FIG. 2, the leakage determination device 1 includes a temperature input section 11, a differential pressure input section 12, a pressure input section 13, a temperature sensor 14, a display section 15, an operation section 16, and a control section 10.

The temperature input section 11 is a terminal to which the temperature sensor 14 is connected. A temperature value indicating the temperature of the fluid filled in the piping of the refrigeration cycle device 2 detected by the temperature sensor 14 is input to the temperature input unit 11 . The temperature sensor 14 is connected to the refrigeration cycle device 2 and acquires the temperature of the refrigeration cycle device 2. For example, a thermocouple is used as the temperature sensor 14.

The differential pressure input section 12 is a terminal to which the differential pressure gauge 5 is connected. A measured differential pressure value, which is the differential pressure between the pressure of the refrigeration cycle device 2 measured by the differential pressure gauge 5 and the pressure of the master container 4, is input to the differential pressure input section 12.

The pressure input section 13 is a terminal to which a pressure sensor 25 (see FIG. 3) provided in the refrigeration cycle device 2 is connected. A pressure value indicating the pressure of the fluid filling the pipes of the refrigeration cycle device 2 from the filling cylinder 3 is input to the pressure input unit 13 .

A value indicating temperature or pressure is input as a current to the temperature input section 11, differential pressure input section 12, and pressure input section 13 to which various sensors are connected, and the input current is converted into a temperature value by the control section 10. or converted into data indicating pressure values. Therefore, it is preferable that the temperature input section 11, the differential pressure input section 12, and the pressure input section 13 are provided on a terminal block such as a control panel, for example.

The display unit 15 displays information regarding the airtightness test, such as operations on the operation unit 16, parameters such as temperature and pressure during the airtightness test, and the presence or absence of leakage due to the airtightness test. The display unit 15 is made of a material that takes into consideration visibility when exposed to sunlight, such as an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) display. Furthermore, a liquid crystal film may be attached to the display section 15 to prevent reflection from sunlight.

In the first embodiment, the display section 15 is divided into a parameter display section 15a that displays parameters such as temperature and pressure, and a leakage display section 15b that displays the presence or absence of leakage during an airtightness test. ing. Note that the display unit 15 is not limited to this, and the parameter display unit 15a and the leakage presence/absence display unit 15b may be integrally provided.

The operation unit 16 is provided to perform various operations such as starting and ending an airtightness test, and includes, for example, buttons and keys operated by a user. For example, it is preferable to use a touch panel having a touch sensor as the operation unit 16 because it can prevent erroneous operations by the user.

In this case, as the display unit 15, for example, a touch panel display in which a touch panel is laminated on the display can be used. Further, when a touch panel display is used as the display section 15 and the operation section 16, various buttons or keys may be displayed on the display section 15 as software buttons or software keys.

The control unit 10 controls the overall operation of the leakage determination device 1 based on information received from various sensors provided in the leakage determination system 100 . In particular, in the first embodiment, the control unit 10 performs a leakage determination process to determine whether there is a leakage in the refrigeration cycle device 2 based on various types of information received during the airtightness test. The control unit 10 is composed of an arithmetic unit such as a microcomputer that implements various functions by executing software, or hardware such as a circuit device that supports various functions. Details of the control unit 10 will be described later.

[Configuration of leakage determination system 100]
Next, a specific configuration of the leakage determination system 100 according to the first embodiment will be described. FIG. 3 is a schematic diagram showing an example of the configuration of the leakage determination system according to the first embodiment. The example shown in FIG. 3 more specifically illustrates the configuration of the leakage determination system 100 shown in FIG. 1. As shown in FIG. 3, the leakage determination system 100 includes a leakage determination device 1, a refrigeration cycle device 2, a filling cylinder 3, a master container 4, and a differential pressure gauge 5. In this example, a case where an air conditioner is used as the refrigeration cycle device 2 will be described.

The air conditioner as the refrigeration cycle device 2 includes an outdoor unit 2a installed outdoors and an indoor unit (not shown) installed in a space to be air-conditioned. The outdoor unit 2a is provided with an outdoor heat exchanger 20 and a compressor (not shown). A heat medium circulation circuit in which a heat medium such as refrigerant or water circulates by connecting the compressor of the outdoor unit 2a and the outdoor heat exchanger 20, and the indoor heat exchanger and pressure reducing valve provided in the indoor unit with piping. (refrigerant circuit) is configured.

The outdoor unit 2a is provided with a filling port 21 and a connection port 22. In this example, two filling ports 21a and 21b and two connection ports 22a and 22b are provided in the piping that constitutes the heat medium circulation circuit, respectively. The filling ports 21a and 21b are connected to the filling cylinder 3, and are filled with fluid during the airtight test. Connection ports 22a and 22b are connected to measurement port 5a of differential pressure gauge 5. Note that the number of each of the filling port 21 and the connection port 22 is not limited to this example, and may be one, three or more.

A filling valve 23 is provided between the filling port 21 and the connecting end of the filling cylinder 3. In this example, a filling valve 23a is provided for the filling port 21a, and a filling valve 23b is provided for the filling port 21b. The filling valves 23a and 23b are, for example, electromagnetic valves, and control passage and shutoff of fluid filled from the filling cylinder 3 by opening and closing. The opening and closing of the filling valves 23a and 23b is controlled by the control unit 10 of the leakage determination device 1.

A connection valve 24 is provided between the connection port 22 and the measurement port 5a of the differential pressure gauge 5. In this example, a connection valve 24a is provided for the connection port 22a, and a connection valve 24b is provided for the connection port 22b. The connection valves 24a and 24b are, for example, electromagnetic valves, and by opening and closing, they control passage and cutoff of fluid supplied to the measurement port 5a of the differential pressure gauge 5. The opening and closing of the connection valves 24a and 24b is controlled by the control unit 10 of the leakage determination device 1.

The filling cylinder 3 is provided to fill the heat medium circulation circuit of the air conditioner with fluid, and is connected to the filling valve 23 of the outdoor unit 2a. The filling cylinder 3 is, for example, a nitrogen gas cylinder filled with nitrogen gas. Note that the fluid used in the airtightness test is not limited to nitrogen gas, and may be other fluids such as air.

A pressure sensor 25 is provided between the filling cylinder 3 and the filling port 21. The pressure sensor 25 detects the pressure of the fluid filled into the heat medium circulation circuit from the filling cylinder 3. The pressure sensor 25 is connected to the pressure input section 13 of the leakage determination device 1 . The pressure sensor 25 is preferably lightweight and highly durable, for example. Furthermore, in a pressurized leakage test, which is an airtightness test, the test is generally performed with nitrogen filled at 2 MPa to 4 MPa or more. Therefore, the pressure resistance of the pressure sensor 25 is preferably 5 MPa or more. Further, the measurement range of the pressure sensor 25 is preferably about -100 kPa to 5 MPa in consideration of measurement accuracy.

The master container 4 is a container that serves as a reference for the pressure of the fluid filled in the heat medium circulation circuit, and the fluid is sealed so that the internal pressure becomes the reference pressure. Master container 4 is connected to reference port 5b of differential pressure gauge 5. It is preferable that the master container 4 can suppress changes in internal fluid pressure as much as possible due to temperature changes. For this reason, the master container 4 is preferably made of stainless steel (SUS304), which has low thermal conductivity, for example. Further, it is preferable that the master container 4 has a wall thickness of about 5 mm or more and a size of about 100 cm to 300 cm that is easy to carry.

Note that the outer peripheral portion of the master container 4 may be covered with a heat insulating material. The heat insulating material in this case is preferably one that has a lower thermal conductivity than the outer circumference of the master container 4 and is easily available, such as urethane foam. Further, it is preferable that the heat insulating material can be easily fixed to the master container 4, for example, by wrapping it with a cable tie or pasting it with double-sided tape.

The differential pressure gauge 5 measures the differential pressure between the pressure of the fluid filled in the heat medium circulation circuit of the air conditioner and the reference pressure due to the fluid sealed in the master container 4. The differential pressure gauge 5 has a measurement port 5a, a reference port 5b, and an output port 5c. The connection port 22 of the outdoor unit 2a is connected to the measurement port 5a, and a portion of the fluid filled in the heat medium circulation circuit is inputted thereto. The master container 4 is connected to the reference port 5b, and a portion of the fluid in the master container 4 is inputted thereto. The differential pressure input section 12 of the leakage determining device 1 is connected to the output port 5c, and an actual differential pressure value ΔP indicating the measured differential pressure is output to the leakage determining device 1.

The differential pressure gauge 5 is preferably lightweight and highly durable, for example. Furthermore, in the pressurized leak test, the test is generally performed with nitrogen filled at 2 MPa to 4 MPa or more. Therefore, the pressure resistance of the differential pressure gauge 5 is preferably 5 MPa or more. Furthermore, the measurement range of the differential pressure gauge 5 is preferably about -150 kPa to 150 kPa so that even the slightest leakage can be detected in consideration of measurement accuracy.

An on-off valve 26a is provided between the measurement port 5a and the connection port 22. Furthermore, an on-off valve 26b is provided between the reference port 5b and the master container 4. The on-off valves 26a and 26b are, for example, electromagnetic valves, and control passage and cutoff of fluid input to the differential pressure gauge 5 by opening and closing. The opening and closing of the on-off valves 26a and 26b is controlled by the control unit 10 of the leakage determination device 1.

The leak determination device 1 determines whether or not there is a leak in the air conditioner, which is the refrigeration cycle device 2, based on the measured differential pressure value ΔP input from the differential pressure gauge 5. A temperature sensor 14 is connected to the temperature input section 11 of the leakage determination device 1 .

The temperature sensor 14 is connected to the outdoor unit 2a of the air conditioner. In particular, the temperature sensor 14 has a particularly large surface area in the heat medium circulation circuit of the air conditioner, which is the refrigeration cycle device 2, and is installed at a location that is easily affected by solar radiation. This is to accurately measure the pressure change due to the temperature rise due to solar radiation on the outdoor unit 2a during the airtightness test. In the first embodiment, the temperature sensor 14 is installed in the piping section of the outdoor heat exchanger 20 of the outdoor unit 2a.

The output port 5c of the differential pressure gauge 5 is connected to the differential pressure input unit 12 of the leakage determination device 1, and the actual differential pressure value ΔP measured by the differential pressure gauge 5 is input.

The leakage determination device 1 is preferably small, for example, about 10 cm long x 10 cm wide x 15 cm high, and made of plastic such as ABS (acrylonitrile butadiene styrene) resin so that it can be easily installed during an airtightness test.

[Configuration of control unit 10]
Next, the configuration of the control unit 10 of the leakage determination device 1 will be explained. FIG. 4 is a functional block diagram showing an example of the configuration of the control section in FIG. 2. As shown in FIG. As shown in FIG. 4, the control unit 10 includes an information acquisition unit 111, a pressure correction unit 112, a calculation unit 113, a leakage determination unit 114, a command unit 115, and a storage unit 116.

The information acquisition unit 111 acquires data from various sensors provided in the leakage determination system 100. For example, the information acquisition unit 111 acquires temperature values such as a first temperature value T1 and a second temperature value T2, which are initial temperature values detected by the temperature sensor 14, through the temperature input unit 11. The first temperature value T1 is the temperature of the fluid at the first point in time when the piping of the air conditioner, which is the refrigeration cycle device 2, is filled with a set amount of fluid from the filling cylinder 3 and the pressure in the piping is equalized. . The second temperature value T2 is the temperature of the fluid in the air conditioner at a second point in time when a set time has elapsed since the differential pressure gauge 5 started measuring the differential pressure between the air conditioner and the master container 4. .

The information acquisition unit 111 also acquires the actual measured differential pressure value ΔP supplied from the differential pressure gauge 5 via the differential pressure input unit 12 . Furthermore, the information acquisition unit 111 acquires pressure values such as the first pressure value P1, which is the initial pressure value detected by the pressure sensor 25, via the pressure input unit 13. The first pressure value P1 is the pressure of the fluid at a first point in time.

The pressure correction unit 112 calculates a temperature-corrected pressure value P2 based on the first temperature value T1 and second temperature value T2 detected by the temperature sensor 14 and the first pressure value P1 detected by the pressure sensor 25. . The temperature-corrected pressure value P2 is a pressure estimated in consideration of temperature changes due to solar radiation, etc., assuming that there is no leakage in the air conditioner.

The calculation unit 113 calculates an estimated differential pressure value "P2-P1 (or P1-P2)" which is the difference between the first pressure value P1 and the temperature-corrected pressure value P2. The estimated differential pressure value is a differential pressure estimated in consideration of temperature changes due to solar radiation, etc., assuming that there is no leakage in the air conditioner. The leak determination unit 114 determines whether or not there is a leak in the refrigeration cycle device 2 based on the measured differential pressure value ΔP supplied from the differential pressure gauge 5 and the estimated differential pressure value calculated by the calculation unit 113.

The command unit 115 controls the operation of each part of the leakage determination device 1 by sending commands to each part. For example, the command unit 115 controls opening and closing of the filling valve 23, the connection valve 24, and the opening/closing valve 26 based on the temperature value, pressure value, etc. acquired by the information acquisition unit 111. Further, the command unit 115 causes the display unit 15 to display the determination result by the leakage determination unit 114.

The storage unit 116 stores various types of information used in each part of the control unit 10. For example, the storage unit 116 stores temperature values such as the first temperature value T1 and the second temperature value T2 detected by the temperature sensor 14, the first pressure value P1 detected by the pressure sensor 25, and the pressure correction unit 112. The temperature-corrected pressure value P2 and other pressure values are stored.

FIG. 5 is a hardware configuration diagram showing an example of the configuration of the control section in FIG. 4. When the various functions of the control unit 10 are executed by hardware, the control unit 10 in FIG. 4 is configured with a processing circuit 51, as shown in FIG. 5. The functions of the information acquisition section 111, pressure correction section 112, calculation section 113, leakage determination section 114, command section 115, and storage section 116 in FIG. 4 are realized by the processing circuit 51.

When each function is executed by hardware, the processing circuit 51 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate). Array), or a combination of these. The functions of the information acquisition section 111, pressure correction section 112, calculation section 113, leakage determination section 114, command section 115, and storage section 116 may be realized by the processing circuit 51, or the functions of each section may be implemented in one process. It may be realized by the circuit 51.

FIG. 6 is a hardware configuration diagram showing another example of the configuration of the control section in FIG. 4. When the various functions of the control unit 10 are executed by software, the control unit 10 in FIG. 4 is configured with a processor 52 and a memory 53, as shown in FIG. The functions of the information acquisition section 111, the pressure correction section 112, the calculation section 113, the leakage determination section 114, the command section 115, and the storage section 116 are realized by the processor 52 and the memory 53.

When each function is executed by software, the functions of the information acquisition unit 111, pressure correction unit 112, calculation unit 113, leakage determination unit 114, command unit 115, and storage unit 116 may be performed by software, firmware, or a combination of software and firmware. This is achieved through a combination. Software and firmware are written as programs and stored in memory 53. The processor 52 reads and executes programs stored in the memory 53 to realize the functions of each section.

Examples of the memory 53 include RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable and Programmable ROM), and EEPROM (Electrically Erasable Memory). non-volatile or volatile semiconductor memory such as and programmable ROM) is used. Further, as the memory 53, a removable recording medium such as a magnetic disk, a flexible disk, an optical disk, a CD (Compact Disc), an MD (Mini Disc), and a DVD (Digital Versatile Disc) may be used.

[Installation of leakage determination device 1]
The installation of the leakage determination device 1 when performing an airtightness test will be explained. First, the leakage determination device 1 is installed at an arbitrary position near the outdoor unit 2a. Further, a differential pressure gauge 5 is connected to the leakage determination device 1 . Specifically, the differential pressure input section 12 of the leakage determination device 1 and the output port 5c of the differential pressure gauge 5 are connected. Further, a differential pressure gauge 5 is connected to the outdoor unit 2a. Specifically, a part of the casing of the outdoor unit 2a is opened, and the connection port 22 provided inside is connected to the measurement port 5a of the differential pressure gauge 5.

Next, a pressure sensor 25 is connected to the pressure input section 13 of the leakage determination device 1 . Further, a pressure sensor 25 is installed at the filling port 21 of the outdoor unit 2a, and the filling cylinder 3 is connected to the filling port 21a. Further, the master container 4 is connected to the reference port 5b of the differential pressure gauge 5.

The temperature sensor 14 is then connected to the outdoor unit 2a. Specifically, the temperature sensor 14 is installed in a piping portion of the outdoor heat exchanger 20 that has a large surface area in the heat medium circulation circuit. In this case, in order to prevent the temperature detected by the temperature sensor 14 from being influenced by outside air, it is preferable that the temperature sensor 14 is installed so that its tip is covered with a heat insulating material or the like.

[Leakage determination processing]
The leakage determination process of the refrigeration cycle device 2 by the leakage determination device 1 will be explained. Here, as an example of an airtightness test, a case will be described in which a nitrogen pressurized leakage test is performed in which piping of an air conditioner, which is the refrigeration cycle device 2, is filled with nitrogen.

7 and 8 are flowcharts showing an example of the flow of leakage determination processing by the leakage determination device according to the first embodiment. Note that in the flowcharts shown in FIGS. 7 and 8, the symbol A indicates that the process moves to the corresponding symbol. When the operator operates the operation unit 16 of the leakage determination device 1 and presses the start button for starting the airtightness test, the airtightness test is started and a series of processes described below are executed.

In step S1, the command unit 115 of the control unit 10 opens each of the filling valves 23a and 23b, the connection valves 24a and 24b, and the on-off valves 26a and 26b. As a result, nitrogen gas as a fluid flows out from the filling cylinder 3, and the piping of the outdoor unit 2a of the air conditioner is filled with nitrogen gas.

In step S2, the control unit 10 determines whether the nitrogen gas filled in the piping of the air conditioner has reached a preset filling amount, such as 2 MPa. When the filling amount of nitrogen gas reaches the set filling amount (step S2: Yes), the command unit 115 closes the filling valves 23a and 23b in step S3. Then, in step S4, the pressure of the nitrogen gas in the pipe is equalized for about 10 to 15 minutes. On the other hand, if the filling amount of nitrogen gas has not reached the set filling amount (step S2: No), the process of step S2 is repeated until the filling amount reaches the setting filling amount.

Next, at a first point in time when pressure equalization is completed, the temperature of the outdoor heat exchanger 20 provided in the outdoor unit 2a is detected by the temperature sensor 14. Then, in step S5, the information acquisition unit 111 acquires a temperature value indicating the temperature detected by the temperature sensor 14, and stores it in the storage unit 116 as the first temperature value T1.

In step S6, the pressure within the piping of the air conditioner at the first point in time is detected by the pressure sensor 25. The information acquisition unit 111 acquires a pressure value indicating the pressure detected by the pressure sensor 25, and stores it in the storage unit 116 as the first pressure value P1. Then, in step S7, the command unit 115 brings the on-off valves 26a and 26b into a "closed" state.

Next, in step S8, measurement of the differential pressure between the air conditioner and the master container 4 using the differential pressure gauge 5 is started. The differential pressure measurement is performed periodically, for example, by the differential pressure gauge 5. The differential pressure gauge 5 measures an actual differential pressure value ΔP, which is a differential pressure between the fluids, based on the fluid supplied from the outdoor unit 2a and the fluid supplied from the master container 4. The information acquisition unit 111 acquires the actual differential pressure value ΔP measured by the differential pressure gauge 5 and stores it in the storage unit 116.

In step S9, the temperature of the outdoor heat exchanger 20 is detected again by the temperature sensor 14 at a second point in time after waiting for a set time after the differential pressure measurement is started and ending the waiting. Then, in step S10, the information acquisition unit 111 acquires a temperature value indicating the temperature detected by the temperature sensor 14, and stores it in the storage unit 116 as a second temperature value T2.

In step S11, the pressure correction unit 112 calculates a temperature-corrected pressure value P2 based on the first temperature value T1, second temperature value T2, and first pressure value P1 stored in the storage unit 116, and stores it in the storage unit 116. Remember. The temperature-corrected pressure value P2 is calculated based on equation (1).
P2=((T2+273.15)/(T1+273.15))×P1
...(1)

In step S12, the leakage determination unit 114 compares the first temperature value T1 and the second temperature value T2, and determines whether the second temperature value T2 is larger than the first temperature value T1. As a result of the comparison, if the second temperature value T2 is larger than the first temperature value T1 (step S12: Yes), that is, if the temperature of the fluid increases during standby, the process moves to step S13. Furthermore, if the second temperature value T2 is less than or equal to the first temperature value T1 (step S12: No), that is, if the temperature of the fluid decreases during standby, the process moves to step S15.

In step S13, the calculation unit 113 calculates an estimated differential pressure value "P2-P1", which is the difference between the temperature-corrected pressure value P2 and the first pressure value P1. Then, the leakage determination unit 114 determines the pressure difference “ΔP−(P2 -P1)" is larger than a preset threshold. Here, the threshold value with which the pressure difference is compared is preferably set to a value corresponding to the resolution of the differential pressure gauge 5 (for example, about 5 kPa) in consideration of the pressure that can be detected by the differential pressure gauge 5.

If the pressure difference is larger than the threshold (step S13: Yes), a pressure difference greater than the estimated differential pressure value has occurred, so the leak determination unit 114 determines that "there is a leak" in step S14. On the other hand, if the pressure difference is less than or equal to the threshold (step S13: No), the process moves to step S16.

In step S15, the calculation unit 113 calculates an estimated differential pressure value "P1-P2" which is the difference between the first pressure value P1 and the temperature-corrected pressure value P2. Then, the leakage determination unit 114 determines the pressure difference “ΔP−(P1 -P2)" is larger than a threshold value.

If the pressure difference is larger than the threshold (step S15: Yes), a pressure difference greater than the estimated differential pressure value has occurred, so the leak determination unit 114 determines that "there is a leak" in step S14. On the other hand, if the pressure difference is less than or equal to the threshold (step S15: No), the process moves to step S16.

In step S16, the leakage determination unit 114 determines whether the test time of the airtightness test is two hours or more. If the test time is 2 hours or more (step S16: Yes), there is no difference in the pressure difference even though the sufficient test time has elapsed, so the leak determination unit 114 determines that , it is determined that there is no leakage. On the other hand, if the test time is less than 2 hours (step S16: No), the process returns to step S10.

In step S<b>18 , the command unit 115 stores information indicating the presence or absence of leakage, which is the determination result, in the storage unit 116 and displays it on the display unit 15 . Then, the command unit 115 brings the connection valves 24a and 24b into a "closed" state. This completes the series of processing.

As described above, the leakage determination device 1 according to the first embodiment uses an estimated differential pressure, which is a differential pressure estimated in consideration of temperature changes due to solar radiation, etc., assuming that there is no leakage in the air conditioner. The calculated estimated differential pressure value is compared with the measured differential pressure value, which is the actual differential pressure, to determine whether there is a leak. If a difference occurs between the estimated differential pressure value and the measured differential pressure value, it can be determined that this difference is due to a factor other than temperature change due to solar radiation, that is, leakage in the piping. In the leakage determination device 1 according to No. 1, the presence or absence of fluid leakage in the refrigeration cycle device 2 can be accurately determined by comparing the estimated differential pressure value and the measured differential pressure value.

Embodiment 2.
Next, Embodiment 2 will be described. The leakage determination device according to the second embodiment sets the first temperature value T1 and the second temperature value T2 used when calculating the temperature-corrected pressure value P2 to parameters including the influence of solar radiation such as the outside air temperature and the amount of solar radiation. This is different from Embodiment 1 in that the information is acquired based on the following. Note that, in the following description, parts common to those in Embodiment 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[Configuration of leakage determination system 200]
FIG. 9 is a schematic diagram showing an example of the configuration of a leakage determination system according to the second embodiment. As shown in FIG. 9, the leakage determination system 200 includes a leakage determination device 1A, a refrigeration cycle device 2, a filling cylinder 3, a master container 4, and a differential pressure gauge 5. In this example, similarly to Embodiment 1, a case will be described in which an air conditioner is used as the refrigeration cycle device 2.

In the second embodiment, the temperature sensor 14 connected to the leakage determination device 1A is installed at any point inside the outdoor unit 2a so as to be able to detect the outside air temperature inside the outdoor unit 2a of the air conditioner, which is the refrigeration cycle device 2. installed in position. The temperature sensor 14 is fixed to the outdoor unit 2a by a simple method such as a tape.

[Configuration of leakage determination device 1A]
FIG. 10 is a schematic diagram showing an example of the configuration of a leakage determination device according to the second embodiment. As shown in FIG. 10, the leakage determination device 1A includes a temperature input section 11, a differential pressure input section 12, a pressure input section 13, a temperature sensor 14, a display section 15, an operation section 16, a pyranometer 17, and a control section 10. ing. The pyranometer 17 is, for example, a global pyranometer, and detects the total amount of solar radiation. Global solar radiation is the amount of solar radiation measured from all directions in the sky.

In the second embodiment, a temperature value indicating the outside air temperature inside the refrigeration cycle device 2 detected by the temperature sensor 14 is input to the temperature input unit 11 . In this case, the control unit 10 performs leakage determination processing during the airtightness test based on the information regarding the temperature and pressure input to each input unit and the total solar radiation detected by the pyranometer 17. The configuration of the control unit 10 is the same as that shown in FIG. 4 when describing the first embodiment.

Note that in the second embodiment, the information acquisition unit 111 of the control unit 10 acquires the total solar radiation amount detected by the pyranometer 17 in addition to the same information as in the first embodiment. Further, the calculation unit 113 calculates the equivalent outside air temperature based on the total solar radiation detected by the pyranometer 17 and the outside air temperature of the outdoor unit 2a detected by the temperature sensor 14. The equivalent outside temperature is the effect of solar radiation converted into temperature and added to the outside temperature. Furthermore, in addition to the same information as in the first embodiment, the storage unit 116 stores the global solar radiation amount detected by the pyranometer 17 and the equivalent outside temperature calculated by the calculation unit 113.

[Leakage determination processing]
Leakage determination processing for the refrigeration cycle device 2 by the leakage determination device 1A will be explained. Here, a case will be described taking as an example a case where a nitrogen pressurized leak test is performed as the airtight test in the same manner as in the first embodiment.

11 and 12 are flowcharts showing an example of the flow of leakage determination processing by the leakage determination device according to the second embodiment. Note that in the flowcharts shown in FIGS. 11 and 12, the symbol B indicates that the process moves to the corresponding symbol. Further, processes common to the leakage determination process according to Embodiment 1 shown in FIGS. 7 and 8 are given the same reference numerals, and detailed description thereof will be omitted here.

When the operator operates the operation unit 16 of the leakage determination device 1 and presses the start button for starting the airtightness test, the airtightness test is started and a series of processes described below are executed. The processing in steps S1 to S4 is the same as in the first embodiment. That is, through these processes, the piping of the air conditioner is filled with a set amount of nitrogen gas and the pressure is equalized.

Next, at a first point in time when pressure equalization is completed, the total solar radiation is detected by the pyranometer 17. Then, in step S21, the information acquisition unit 111 acquires the total solar radiation detected by the pyranometer 17. Furthermore, at the first time point, the temperature sensor 14 detects the outside air temperature inside the outdoor unit 2a. In step S22, the information acquisition unit 111 acquires the outside air temperature detected by the temperature sensor 14.

In step S23, the calculation unit 113 calculates the equivalent outside temperature based on the total solar radiation and outside temperature acquired by the information acquisition unit 111. Then, in step S24, the calculation unit 113 stores the calculated equivalent outside air temperature in the storage unit 116 as the first temperature value T1. The equivalent outside air temperature is calculated based on equation (2). Here, in equation (2), the total solar radiation [W/m ² ] is the value detected by the pyranometer 17, and the outdoor heat transfer coefficient is 5 to 10 [W/m ² ·K]. Further, the solar radiation absorption rate is set to about 0.3 to 0.4 based on the solar radiation absorption rate of the piping portion of the outdoor heat exchanger 20, which has a large surface area.
Equivalent outside air temperature = outside air temperature + (solar absorption rate x total solar radiation) / outdoor heat transfer coefficient
...(2)

The processing in steps S6 to S9 is the same as in the first embodiment. That is, through these processes, the first pressure value P1 is acquired, and the differential pressure gauge 5 starts measuring the actual differential pressure value ΔP, and waits for a set time.

At a second point in time when the standby ends, the total solar radiation amount is detected by the pyranometer 17, and the outside air temperature inside the outdoor unit 2a is detected by the temperature sensor 14. Then, in step S25, the information acquisition unit 111 acquires the total solar radiation amount detected by the pyranometer 17 again. Further, in step S26, the information acquisition unit 111 acquires the outside air temperature detected by the temperature sensor 14 again.

In step S27, the calculation unit 113 calculates the equivalent outside temperature using equation (2) based on the total solar radiation and outside temperature acquired by the information acquisition unit 111. Then, in step S28, the calculation unit 113 stores the calculated equivalent outside air temperature in the storage unit 116 as the second temperature value T2.

Thereafter, based on the first temperature value T1, second temperature value T2, and first pressure value P1 obtained in this way, steps S11 to S19 are performed in the same manner as in the first embodiment.

As described above, the leakage determination device 1A according to the second embodiment is calculated using the first temperature value T1 and the second temperature value T2 obtained based on the total solar radiation amount and the outside air temperature of the outdoor unit 2a. The estimated differential pressure value and the measured differential pressure value are compared to determine whether there is a leak in the refrigeration cycle device 2. Thereby, the presence or absence of fluid leakage in the refrigeration cycle device 2 can be determined with high accuracy, similarly to the first embodiment.

Embodiment 3.
Next, Embodiment 3 will be described. The leakage determination device 1 according to the third embodiment uses temperature information of the refrigeration cycle device 2 as the first temperature value T1 and the second temperature value T2 used when calculating the temperature-corrected pressure value P2. This is different from Embodiments 1 and 2. In the following description, parts common to those in Embodiments 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[Configuration of leakage determination system 300]
FIG. 13 is a schematic diagram showing an example of the configuration of a leakage determination system according to the third embodiment. As shown in FIG. 13, the leakage determination system 300 includes a leakage determination device 1B, a refrigeration cycle device 2, a filling cylinder 3, a master container 4, and a differential pressure gauge 5. In this example, similarly to Embodiments 1 and 2, a case will be described in which an air conditioner is used as the refrigeration cycle device 2.

In the third embodiment, the temperature input section 11 of the leakage determination device 1B is connected to an outdoor control device 27 provided in an outdoor unit 2a of an air conditioner, which is the refrigeration cycle device 2. The leakage determination device 1B acquires, via the temperature input unit 11, the temperature detected by a temperature sensor or the like provided in the outdoor unit 2a.

Note that the leakage determination device 1B is the same as the leakage determination device 1 according to the first embodiment, except that the temperature value input to the temperature input unit 11 is acquired by the outdoor control device 27. That is, the control unit 10 of the leakage determination device 1B performs leakage determination processing based on information regarding temperature and pressure input to each input unit during the airtightness test.

[Leakage determination processing]
Leakage determination processing for the refrigeration cycle device 2 by the leakage determination device 1B will be described. Here, an example will be described in which a nitrogen pressurized leak test is performed as the airtight test in the same manner as in Embodiments 1 and 2.

14 and 15 are flowcharts showing an example of the flow of leakage determination processing by the leakage determination device according to the third embodiment. Note that in the flowcharts shown in FIGS. 14 and 15, the symbol C indicates that the process moves to the corresponding symbol. In addition, the same reference numerals are given to processes common to the leakage determination process according to the first embodiment shown in FIGS. 7 and 8 and the leakage determination process according to the second embodiment shown in FIGS. 11 and 12, A detailed explanation will be omitted here.

When the operator operates the operation unit 16 of the leakage determination device 1 and presses the start button for starting the airtightness test, the airtightness test is started and a series of processes described below are executed. Note that the basic processing in the leakage determination processing is the same as in the first embodiment. However, in the third embodiment, steps S31 and S32 are performed in place of step S5 (see FIG. 7) and step S10 (see FIG. 8) of the first embodiment.

In step S31, the information acquisition unit 111 acquires a temperature value from the outdoor control device 27, and stores it in the storage unit 116 as the first temperature value T1. Further, in step S32, the information acquisition unit 111 acquires a temperature value from the outdoor control device 27, and stores it in the storage unit 116 as a second temperature value T2.

As described above, the leakage determination device 1B according to the third embodiment compares the estimated differential pressure value calculated using the temperature information obtained from the outdoor control device 27 of the outdoor unit 2a and the measured differential pressure value. Then, the presence or absence of leakage in the refrigeration cycle device 2 is determined. Thereby, as in Embodiments 1 and 2, it is possible to accurately determine whether there is a fluid leak in the refrigeration cycle device 2.

1, 1A, 1B Leak determination device, 2 Refrigeration cycle device, 2a Outdoor unit, 3 Filling cylinder, 4 Master container, 5 Differential pressure gauge, 5a Measurement port, 5b Reference port, 5c Output port, 10 Control unit, 11 Temperature input unit , 12 differential pressure input section, 13 pressure input section, 14 temperature sensor, 15 display section, 15a parameter display section, 15b leakage display section, 16 operation section, 17 pyranometer, 20 outdoor heat exchanger, 21, 21a, 21b Filling port, 22, 22a, 22b Connection port, 23, 23a, 23b Filling valve, 24, 24a, 24b Connection valve, 25 Pressure sensor, 26a, 26b Opening/closing valve, 27 Outdoor control device, 51 Processing circuit, 52 Processor, 53 memory, 100, 200, 300 leakage determination system, 111 information acquisition section, 112 pressure correction section, 113 calculation section, 114 leakage determination section, 115 command section, 116 storage section.

Claims (9)

A leakage determination device that determines the presence or absence of fluid leakage in a refrigeration cycle device in which piping forming a heat medium circulation circuit is filled with fluid,
a temperature input section into which the temperature of the fluid filled in the piping or the outside air temperature within the refrigeration cycle device is input;
a pressure input section into which the pressure of the fluid when the piping is filled with a set amount;
a differential pressure input section into which a measured differential pressure value that is a difference between the pressure of the fluid in the piping and a reference pressure is input;
Obtaining the temperature of the fluid or the outside air temperature input to the temperature input section, the pressure of the fluid input to the pressure input section, and the measured differential pressure value input to the differential pressure input section. Information acquisition department;
A first temperature value that is the temperature of the fluid or the outside air temperature at a first time point when the pipe is filled with a set amount of the fluid, and a first pressure value that is the pressure inside the pipe at the first time point. and a second temperature value that is the temperature of the fluid or the outside air temperature at a second time point when a set time has elapsed from the first time point, a temperature-corrected pressure value that is the estimated pressure at the second time point. a pressure correction unit that calculates
a calculation unit that calculates an estimated differential pressure value that is a difference between the first pressure value and the temperature-corrected pressure value;
A leak determination device comprising: a leak determination unit that determines whether or not there is a leak of the fluid in the refrigeration cycle device based on a pressure difference that is a difference between the measured differential pressure value and the estimated differential pressure value. The refrigeration cycle device includes:
An air conditioner that is equipped with an outdoor unit having an outdoor heat exchanger and performs air conditioning in a space to be air-conditioned.
The temperature input section is
A temperature sensor is connected to detect the pipe temperature of the outdoor heat exchanger,
The information acquisition unit includes:
The leakage determination device according to claim 1, which acquires the temperature of the fluid flowing through the outdoor heat exchanger detected by the temperature sensor. It is also equipped with a pyranometer that measures global solar radiation.
The refrigeration cycle device includes:
It is an air conditioner equipped with an outdoor unit and performs air conditioning in a space to be air-conditioned.
The temperature input section is
A temperature sensor that detects outside air temperature inside the outdoor unit is connected,
The information acquisition unit includes:
obtaining the outside air temperature detected by the temperature sensor;
The arithmetic unit is
The first temperature value is calculated based on the total solar radiation amount and the outside air temperature at the first time point, and the second temperature value is calculated based on the total solar radiation amount and the outside air temperature at the second time point. The leakage determination device according to claim 1, wherein the leakage determination device calculates. The refrigeration cycle device includes:
An air conditioner that includes an outdoor unit and an outdoor control device that controls the outdoor unit, and performs air conditioning in a space to be air-conditioned;
The temperature input section is
The temperature acquired by the outdoor control device is input,
The information acquisition unit includes:
The leakage determination device according to claim 1, wherein the temperature input to the temperature input section is acquired as the temperature of the fluid. The leakage determination section includes:
determining that the fluid is leaking if the pressure difference is larger than a threshold;
The leakage determination device according to any one of claims 1 to 4, which determines that the fluid is not leaking when the pressure difference is less than or equal to the threshold value. The leakage determination device according to any one of claims 1 to 5, further comprising a display unit that displays the determination result of the presence or absence of leakage. The leakage determination device according to any one of claims 1 to 6, further comprising an operation unit for starting and ending a leakage determination process for determining whether or not there is a leakage of the fluid in the refrigeration cycle device. A leakage determination system that determines the presence or absence of fluid leakage in a refrigeration cycle device in which piping forming a heat medium circulation circuit is filled with fluid, the system comprising:
a filling cylinder filled with fluid to be filled into the piping of the refrigeration cycle device;
a master container sealed with a fluid having a reference pressure that is a reference for the pressure of the fluid;
a differential pressure gauge that measures an actual differential pressure value that is the difference between the pressure of the fluid in the piping of the refrigeration cycle device and the reference pressure;
and a leakage determination device that determines whether or not there is a leakage of the fluid in the refrigeration cycle device,
The leakage determination device includes:
a temperature input section into which the temperature of the fluid filled in the piping or the outside air temperature within the refrigeration cycle device is input;
a pressure input section into which the pressure of the fluid when the piping is filled with a set amount;
a differential pressure input section into which the measured differential pressure value is input;
Obtaining the temperature of the fluid or the outside air temperature input to the temperature input section, the pressure of the fluid input to the pressure input section, and the measured differential pressure value input to the differential pressure input section. Information acquisition department;
A first temperature value that is the temperature of the fluid or the outside air temperature at a first time point when the pipe is filled with a set amount of the fluid, and a first pressure value that is the pressure inside the pipe at the first time point. and a second temperature value that is the temperature of the fluid or the outside air temperature at a second time point when a set time has elapsed from the first time point, a temperature-corrected pressure value that is the estimated pressure at the second time point. a pressure correction unit that calculates
a calculation unit that calculates an estimated differential pressure value that is a difference between the first pressure value and the temperature-corrected pressure value;
A leakage determination system comprising: a leakage determination unit that determines whether or not there is a leakage of the fluid in the refrigeration cycle device based on a pressure difference that is a difference between the measured differential pressure value and the estimated differential pressure value. The master container is
9. The leakage determination system according to claim 8, wherein the outer circumferential portion is covered with a heat insulating material having a thermal conductivity lower than that of the outer circumferential portion.

Images