Refrigeration device, refrigerant leakage determination method, and program

Abstract

To suppress erroneous determination of leakage of a refrigerant due to breathing of vegetables and fruits and flowering plants.SOLUTION: The controller (100) selectively performs a first operation of determining leakage of the carbon dioxide refrigerant based on a detection value of the sensor (63), and a second operation of determining leakage of the carbon dioxide refrigerant based on an operation state of the refrigerant circuit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration device, a refrigerant leakage determination method, and a program. [Background technology]

[0002] Patent Document 1 discloses a refrigeration system that uses carbon dioxide as a refrigerant and operates in a refrigeration cycle. The refrigeration system has a sensor that detects the carbon dioxide concentration in a container. When refrigerant leaks from the refrigeration system's refrigeration circuit and the detected value of the sensor exceeds a predetermined value, a display device notifies the operator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-510294 Summary of the Invention [Problem to be solved by the invention]

[0004] The refrigerator compartment may contain items that consume oxygen to breathe, such as fruits, vegetables, and flowers. When these items breathe, the carbon dioxide concentration in the compartment increases. This can lead to a false determination that a refrigerant leak has occurred based on the sensor's detection value, even if there is no refrigerant leaking from the refrigerant circuit.

[0005] An object of the present disclosure is to prevent erroneous determination of refrigerant leakage due to respiration of fruits, vegetables, and flowers. [Means for solving the problem]

[0006] The first aspect relates to a refrigeration system. The refrigeration system includes a refrigerant circuit (R) having a compressor (25), a radiator (26), an expansion mechanism (31), and an evaporator (29) and performing a refrigeration cycle using carbon dioxide as a refrigerant, a sensor (63) for detecting a carbon dioxide concentration in an interior space (3) cooled by the evaporator (29), and a controller (100). The controller (100) selectively performs a first operation for determining whether a refrigerant leaks based on a value detected by the sensor (63) and a second operation for determining whether a refrigerant leaks based on an operating state of the refrigerant circuit (R).

[0007] In the first mode, the controller (100) selectively executes a first operation and a second operation. In the second operation, the controller (100) determines whether or not there is a refrigerant leak based on the operating state of the refrigerant circuit (R), and is therefore not affected by the respiration of the fruit, vegetable, or flower. Therefore, by executing the second operation in accordance with predetermined conditions, it is possible to determine whether or not there is a refrigerant leak without being affected by the respiration of the fruit, vegetable, or flower.

[0008] In the second aspect, in the first aspect, the controller (100) determines whether a first condition is met, which indicates that fruits, vegetables, or flowers are present in the interior space (3). If the first condition is met, the controller (100) performs a second operation, and if the first condition is not met, the controller (100) performs the first operation.

[0009] In the second mode, the controller (100) performs the second operation when a first condition is met, which indicates the presence of fruits, vegetables, or flowers in the interior space (3). This makes it possible to determine whether there is a refrigerant leak without being affected by the respiration of the fruits, vegetables, or flowers.

[0010] The controller (100) performs the first operation when the first condition is not satisfied, i.e., when there are no fruits, vegetables, or flowers in the internal space (3). In this case, the carbon dioxide concentration in the internal space (3) does not increase due to respiration of the fruits, vegetables, or flowers, and therefore the sensor (63) can quickly determine whether there is a refrigerant leak.

[0011] In the third embodiment, the second embodiment is provided with a regulator (50) that performs a regulation operation for regulating the composition of air in the interior space (3).

[0012] In the third embodiment, the composition of the air in the interior space (3) can be adjusted by the adjustment device (50).

[0013] In a fourth aspect, in the third aspect, the controller (100) determines that refrigerant has leaked when a second condition is met in which the detected value of the sensor (63) is greater than the control range of the carbon dioxide concentration in the internal space (3) in the adjustment operation.

[0014] In the fourth mode, when the detected value of the sensor (63) is greater than the control range of the carbon dioxide concentration in the adjustment operation, the controller (100) determines that refrigerant has leaked. This is because when the carbon dioxide concentration in the internal space (3) exceeds the control range of the adjustment operation, there is an extremely high possibility that refrigerant has leaked.

[0015] A fifth aspect is the third or fourth aspect, wherein the first condition includes a condition that the adjustment device (50) is in an adjustment operation.

[0016] In the fifth aspect, the condition that the adjustment device (50) is performing an adjustment operation is used as the first condition indicating the presence of fruits, vegetables, or flowers in the internal space (3). This is because when the adjustment device (50) is performing an adjustment operation, there is a high possibility that fruits, vegetables, or flowers are present in the internal space (3).

[0017] A sixth aspect is any one of the second to fifth aspects, wherein the first condition includes a condition that the set temperature of the air in the interior space (3) is higher than a predetermined temperature lower than 0°C.

[0018] In the sixth aspect, the first condition indicating the presence of fruits, vegetables, or flowers in the internal space (3) is that the set temperature of the air in the internal space (3) is higher than a predetermined temperature lower than 0° C. This is because when fruits, vegetables, or flowers are stored in the internal space (3), it is highly likely that the set temperature will be relatively high in order to maintain their quality.

[0019] A seventh aspect is any one of the second to sixth aspects, wherein the first condition includes a condition that the rate of decrease in the oxygen concentration in the internal space (3) is greater than a predetermined value.

[0020] In the seventh aspect, the first condition indicating the presence of fruits, vegetables, or flowers in the interior space 3 is that the rate of decrease in the oxygen concentration in the interior space 3 is greater than a predetermined value. This is because, when fruits, vegetables, or flowers are present in the interior space 3, they consume oxygen in the interior space 3, and the rate of decrease in the oxygen concentration increases.

[0021] An eighth aspect is any one of the second to seventh aspects, wherein the first condition includes a condition in which information indicating that the stored items in the internal space (3) are fruits or vegetables or flowers is input to the controller (100), or a condition in which the ethylene concentration in the internal space (3) is equal to or greater than a predetermined value, or a condition in which the amount of moisture generated in the internal space (3) is equal to or greater than a predetermined value, or a condition in which the cooling load on the internal space (3) has increased.

[0022] In an eighth aspect, the first condition includes a condition in which information indicating that the stored items in the internal space (3) are fruits, vegetables, or flowers has been input to the controller (100). When this information is input, it means that fruits, vegetables, or flowers are stored in the internal space (3).

[0023] The first condition includes a condition that the ethylene concentration in the internal space (3) is equal to or higher than a predetermined value, because the ethylene concentration in the internal space (3) increases when fruits or vegetables are present in the internal space (3).

[0024] The first condition includes a condition indicating that the amount of moisture generated in the internal space (3) is equal to or greater than a predetermined value, because moisture is generated in the internal space (3) when the fruits, vegetables, or flowers in the internal space (3) breathe.

[0025] The first condition includes a condition indicating that the cooling load of the internal space (3) has increased. This is because when the fruits, vegetables, and flowers in the internal space (3) respire, respiratory heat is generated in the internal space (3), which increases the cooling load of the internal space (3).

[0026] In a ninth aspect, the controller (100) determines that refrigerant has leaked if the rate of increase in the detected value of the sensor (63) is greater than a predetermined value when the adjustment device (50) is not performing an adjustment operation.

[0027] In the ninth aspect, the controller (100) determines that refrigerant has leaked when the adjustment operation is not being performed and the rate of increase in the carbon dioxide concentration detected by the sensor (63) is greater than a predetermined value. This is because if refrigerant leaks when the adjustment operation is not being performed, the carbon dioxide concentration will rise sharply.

[0028] In a tenth aspect, in any one of the first to ninth aspects, the refrigeration system (10) further includes an internal fan (30) that transports air in the internal space (3). When the refrigeration system (10) is switched from an OFF state to an ON state, the controller (100) operates the internal fan (30) and determines whether or not there is a refrigerant leak based on the detection value of the sensor (63).

[0029] In the tenth aspect, when the refrigeration unit (10) is switched from an OFF state to an ON state, the internal fan (30) is operated to agitate the air in the internal space (3). Under such circumstances, the controller (100) determines whether or not there is a refrigerant leak based on the detected value of the sensor (63). Therefore, even if there is a refrigerant leak in the refrigerant circuit (R) when the refrigeration unit (10) is in the OFF state, this can be quickly determined.

[0030] In an eleventh aspect, in any one of the first to tenth aspects, in the second operation, the controller (100) determines whether or not there is a refrigerant leak based on the pressure of the refrigerant in the refrigerant circuit (R), the temperature of the refrigerant in the refrigerant circuit (R), or the opening of the expansion valve (31) serving as an expansion mechanism.

[0031] In the eleventh aspect, based on such an index relating to the operating state of the refrigerant circuit (R), it is possible to determine refrigerant leakage without being affected by the respiration of fruits and vegetables and flowers.

[0032] In a twelfth aspect, in any one of the first to eleventh aspects, the refrigeration apparatus further includes a ventilation unit (40, 50) that performs a ventilation operation to ventilate the interior space (3). When it is determined that there is a refrigerant leak, the controller (100) causes the ventilation unit (40, 50) to perform the ventilation operation.

[0033] In the twelfth aspect, when it is determined that a refrigerant leaks, the ventilation unit (40, 50) performs the ventilation operation, so that the carbon dioxide concentration in the internal space (3) can be reduced quickly.

[0034] A thirteenth aspect is a method for determining refrigerant leakage in a refrigeration system including a refrigerant circuit (R) having a compressor (25), a radiator (26), an expansion mechanism (31), and an evaporator (29) and performing a refrigeration cycle using carbon dioxide as a refrigerant, and a sensor (63) for detecting a carbon dioxide concentration in an interior space (3) cooled by the evaporator (29). The refrigerant leakage determination method selectively performs a first operation for determining refrigerant leakage based on a value detected by the sensor (63) and a second operation for determining refrigerant leakage based on an operating state of the refrigerant circuit (R).

[0035] A fourteenth aspect is a program for causing a computer to execute the refrigerant leakage determination method of the thirteenth aspect. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a perspective view of a container refrigeration unit according to an embodiment, as seen from the front. [Figure 2] FIG. 2 is a vertical cross-sectional view of a container refrigeration unit. [Figure 3] FIG. 3 is a block diagram of the main components of the container refrigeration system. [Figure 4] FIG. 4 is a piping diagram of a container refrigeration unit. [Figure 5] FIG. 5 is a flowchart of the basic control of the refrigerant leakage determination method. [Figure 6] FIG. 6 is a flowchart of a method for determining whether the first condition is met. [Figure 7]FIG. 7 is a flowchart of a method for determining refrigerant leakage when the container refrigeration unit is turned on. [Figure 8] FIG. 8 is a flowchart of the basic control of the refrigerant leakage determination method according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0038] (1) Overall configuration of container refrigeration unit A container refrigeration unit (10) will be described. As shown in Figures 1 and 2, the container refrigeration unit (10) is provided in a container (1). The container (1) is used for marine transportation. The container (1) is a refrigerated container that cools the air inside the container (1). The container (1) has a container body (2) and a container refrigeration unit (10). The container body (2) stores objects. The objects include fruits, vegetables, and flowers. The container refrigeration unit (10) of this embodiment has a function of adjusting the composition of the air inside the container (1).

[0039] As shown in FIG. 2, a front opening (4) is formed in the front of the container body (2). The container refrigeration unit (10) is attached to the container body (2) so as to close the front opening (4). The container refrigeration unit (10) has a cooling unit (U), a ventilation unit (40), and an adjustment unit (50). The cooling unit (U) cools the air in the interior space (3) of the container body (2). The ventilation unit (40) ventilates the interior space (3). The adjustment unit (50) adjusts the composition of the air in the interior space (3).

[0040] (2) Cooling unit The cooling unit (U) has a casing (11), an internal fan (30), an external fan (27), and a refrigerant circuit (R). The refrigerant circuit (R) mainly has a compressor (25), an external heat exchanger (26), an expansion valve (31) as an expansion mechanism, and an internal heat exchanger (29). The refrigerant circuit (R) performs a refrigeration cycle using carbon dioxide as a refrigerant.

[0041] (2-1) Casing The casing (11) forms a lid for the front opening (4) of the container body (2). The casing (11) has a casing main body (12) and a partition plate (13). The casing main body (12) separates the external space (5) from the internal space (3). The partition plate (13) is located on the back side (rear side) of the casing (11).

[0042] As shown in Fig. 2, the casing body (12) has a flat plate portion (12a) and a recessed portion (12b). The flat plate portion (12a) is formed on the upper part of the casing body (12) so as to be substantially flush with the front opening (4) of the casing (11). As shown in Fig. 1, the flat plate portion (12a) is provided with an inspection window (22). The inspection window (22) is located on the right side of the flat plate portion (12a). The inspection window (22) is a transparent window through which the inside of the casing body (12) can be seen.

[0043] The recess (12b) is formed in the lower part of the casing (11). The recess (12b) is recessed rearward from the lower end of the flat plate portion (12a). An external storage space (14) is formed in front of the recess (12b). An internal storage space (15) is formed above the recess (12b) and between the flat plate portion (12a) and the partition plate (13). The lower end of the recess (12b) forms a bottom plate (12c). The bottom plate (12c) extends to both the left and right ends of the casing body (12).

[0044] (2-2) Partition plate and air passage As shown in FIG. 2, the partition plate (13) is a plate-like member located behind the recessed portion (12b). The partition plate (13) extends in the vertical direction so as to be spaced a predetermined distance from the rear surface of the recessed portion (12b). An internal passageway (16), through which internal air flows, is formed between the casing body (12) and the partition plate (13). An inlet port (20) is formed between the upper end of the partition plate (13) and the upper wall (2a) of the container body (2). The inlet port (20) connects the internal space (3) with the inlet end of the internal passageway (16). An outlet port (21) is formed between the lower end of the partition plate (13) and the lower wall (2b) of the container body (2). The outlet port (21) connects the internal space (3) with the outlet end of the internal passageway (16).

[0045] (2-3) Equipment outside the warehouse The compressor (25) is installed on the bottom plate (12c) of the casing (11). The compressor (25) is disposed near the bottom of the external storage space (14). The compressor (25) is disposed near the right of the external storage space (14).

[0046] The external fan (27) is located near the upper part of the external storage space (14). The external fan (27) is a propeller fan. As shown in FIG. 2, an external passage (28) through which outside air flows is formed behind the external fan (27).

[0047] The external heat exchanger (26) is disposed above the compressor (25) in the external storage space (14). The external heat exchanger (26) is located in the external passage (28). The external heat exchanger (26) is a fin-and-tube heat exchanger.

[0048] (2-4) Equipment inside the warehouse An internal heat exchanger (29) and an internal fan (30) are provided in the internal storage space (15). The internal heat exchanger (29) is supported by the casing (11) so as to span the casing body (12) and the partition plate (13). The internal heat exchanger (29) is a fin-and-tube heat exchanger.

[0049] (2-5) Refrigerant circuit As shown in FIG. 4, the cooling unit (U) has a refrigerant circuit (R). The compressor (25) compresses the sucked refrigerant. The compressor (25) discharges the compressed refrigerant. A discharge pipe (32) is connected to a discharge portion of the compressor (25). A suction pipe (33) is connected to a suction portion of the compressor (25). An accumulator (34) is provided in the suction pipe (33). The accumulator (34) is a container for storing liquid refrigerant.

[0050] The external heat exchanger (26) exchanges heat between the refrigerant flowing therethrough and the external air. The gas end of the external heat exchanger (26) communicates with the discharge pipe (32). The liquid end of the external heat exchanger (26) is connected to the liquid end of the internal heat exchanger (29) via a liquid pipe (35). The external heat exchanger (26) functions as a radiator (condenser) that radiates heat from the refrigerant to the air.

[0051] The expansion valve (31) is provided in the liquid pipe (35). The expansion valve (31) is an expansion mechanism that reduces the pressure of high-pressure refrigerant to low-pressure refrigerant. The expansion valve (31) is an electronic expansion valve with an adjustable opening. The expansion mechanism may be a capillary tube or an expander. A receiver (36) is provided in the liquid pipe (35) between the external heat exchanger (26) and the expansion valve (31). The receiver (36) is a container that stores excess refrigerant in the refrigerant circuit (R).

[0052] The internal heat exchanger (29) exchanges heat between the refrigerant flowing therethrough and the internal air. The gas end of the internal heat exchanger (29) communicates with the suction pipe (33). The internal heat exchanger (29) functions as an evaporator in which the refrigerant absorbs heat from the air, thereby cooling the internal air in the internal space (3).

[0053] (3) Ventilation equipment The ventilation device (40) performs a ventilation operation to ventilate the internal space (3) of the container body (2). The ventilation device (40) of this embodiment has an air supply function to supply external air to the internal space (3) and an exhaust function to exhaust the internal air to the external space (5).

[0054] As shown in Fig. 1, the ventilation device (40) is disposed in the left portion of the flat plate portion (12a) of the casing body (12). As shown in Fig. 2, the ventilation device (40) is provided in a ventilation mounting opening (6) formed in the front surface of the casing body (12). The ventilation mounting opening (6) penetrates the casing body (12) from front to rear.

[0055] An air supply passage (41) and an exhaust passage (42) are formed inside the ventilation device (40). The air supply passage (41) and the exhaust passage (42) communicate between the internal space (3) and the external space (5). Specifically, the inflow end of the air supply passage (41) communicates with the external space (5). The outflow end of the air supply passage (41) communicates with the primary side (upstream side) of the internal fan (30) in the internal passage (16). The inflow end of the exhaust passage (42) communicates with the secondary side (downstream side) of the internal fan (30) in the internal passage (16). The outflow end of the exhaust passage (42) communicates with the external space (5).

[0056] The ventilation device (40) has a ventilation fan. The ventilation fan is configured by the above-described internal fan (30). In this embodiment, the internal fan (30) serves both as the ventilation device (40) and the cooling unit (U). When the internal fan (30) is driven, outside air from the external space (5) is supplied to the internal space (3) through the air supply passage (41). At the same time, inside air from the internal space (3) is exhausted to the external space (5) through the exhaust passage (42).

[0057] An air supply communication port (41a) is formed at an end of the air supply passage (41) on the side of the external space (5). An air exhaust communication port (42a) is formed at an end of the air exhaust passage (42) on the side of the external space (5).

[0058] As shown in Fig. 2, the ventilation device (40) includes a motor (43), a drive shaft (44) that is rotationally driven by the motor (43), and an open / close lid (45) that is connected to the drive shaft (44). The motor (43) is a stepping motor. The drive shaft (44) is directly connected to the motor (43).

[0059] The open-close lid (45) is provided in front of the drive shaft (44). The open-close lid (45) is rotatable about the axis of the drive shaft (44). The open-close lid (45) opens and closes the air supply passage (41) and the air exhaust passage (42) according to the angle of rotation of the open-close lid (45). By adjusting the angle of rotation of the open-close lid (45) between the closed position and the fully open position, the opening degrees of the air supply passage (41) and the air exhaust passage (42) are adjusted, and the ventilation volume of the ventilation device (40) is also adjusted.

[0060] (4) Adjustment device The regulator (50) regulates the composition of the air in the internal space (3). Specifically, the regulator (50) performs a regulation operation to regulate the oxygen concentration, carbon dioxide concentration, and nitrogen concentration of the air in the internal space (3). As shown in FIG. 2, the regulator (50) is disposed in the external storage space (14) of the casing (11). The regulator (50) includes a supply path (51), an exhaust path (52), an air pump (53), and a PSA device (54).

[0061] The supply path (51) is a flow path for introducing outside air into the internal space (3). An inflow end of the supply path (51) opens to the external space (5). An outflow end of the supply path (51) communicates with the internal space (3). The exhaust path (52) is a flow path for discharging air from the PSA unit (54) to the external space (5).

[0062] The supply path 51 is provided with an air pump 53 and a PSA device 54. The air pump 53 is a transport unit that transports air. The air pump 53 also functions as a pressurizing unit that pressurizes air and a decompressing unit that decompresses air.

[0063] The PSA unit (54) is a main body of the adjustment unit for adjusting the composition of air. The PSA unit (54) has two adsorption units. The adsorption units are adsorption towers filled with an adsorbent that adsorbs nitrogen in the air. The adsorbent is, for example, zeolite. The main body of the adjustment unit may be, for example, a gas separation membrane device.

[0064] The air pump (53) pressurizes one of the two adsorption sections and depressurizes the other. In the pressurized adsorption section, nitrogen in the air is adsorbed by the adsorbent, thereby generating oxygen-enriched air having a lower nitrogen concentration and a higher oxygen concentration than the air outside the compartment. In the depressurized adsorption section, nitrogen is desorbed from the adsorbent, thereby generating nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration than the air outside the compartment. The oxygen-enriched air is discharged to the external space (5) through the exhaust path (52). The nitrogen-enriched air is supplied to the internal space (3) through the supply path (51). This adjusts the oxygen concentration in the internal space (3).

[0065] (5) Other configurations (5-1) Sensor The container refrigeration system (10) has a plurality of sensors. As shown in Figures 2 and 3, the plurality of sensors include an inside temperature sensor (61), an outside temperature sensor (62), a carbon dioxide sensor (63), and an oxygen sensor (64).

[0066] The internal temperature sensor (61) detects the temperature of the internal air in the container (1). The internal temperature sensor (61) is arranged in the internal passage (16) upstream of the internal fan (30) in the air flow direction. The internal temperature sensor (61) is arranged near the inlet (20) of the internal passage (16).

[0067] The outside-compartment temperature sensor (62) detects the temperature of the outside air outside the container (1). The outside-compartment temperature sensor (62) is arranged in the external passage (28) upstream of the external heat exchanger (26) in the air flow direction. The outside-compartment temperature sensor (62) is arranged near the inlet of the external passage (28).

[0068] The carbon dioxide sensor (63) detects the carbon dioxide concentration in the internal space (3). The carbon dioxide sensor (63) is arranged in the internal passage (16). The carbon dioxide sensor (63) is arranged in the internal passage (16) upstream of the internal fan (30) in the airflow direction. The carbon dioxide sensor (63) is arranged in an upper part of the internal passage (16). The carbon dioxide sensor (63) may be arranged in the internal passage (16) downstream of the internal fan (30) in the airflow direction. The carbon dioxide sensor (63) may be arranged in a lower part of the internal passage (16). The carbon dioxide sensor (63) is formed, for example, by a non-dispersive infrared (NDIR) sensor.

[0069] The oxygen sensor (64) detects the oxygen concentration in the internal space (3). The oxygen sensor (64) is disposed in the internal passage (16). For example, the oxygen sensor (64) is disposed in the internal passage (16) upstream of the internal fan (30) in the air flow direction. The oxygen sensor (64) may also be disposed in the internal passage (16) downstream of the internal fan (30) in the air flow direction. The oxygen sensor (64) is formed, for example, by a zirconia sensor.

[0070] (5-2) Control Unit As shown in Figure 3, the container refrigeration system (10) has a controller (100). The controller (100) controls the cooling unit (U), the ventilation system (40), and the adjustment system (50). The controller (100) includes a microprocessor, an electric circuit, and an electronic circuit. The microprocessor includes a CPU (Central Processing Unit), a memory, a communication interface, an analog input / output, and a contact input / output interface. The memory stores various programs to be executed by the CPU and data used by the programs.

[0071] The controller (100) controls each device of the cooling unit (U). Specifically, the controller (100) controls the rotation speed of the compressor (25), the rotation speed of the internal fan (30), the rotation speed of the external fan (27), the opening of the expansion valve (31), etc. The controller (100) controls the motor (43) of the ventilation device (40). The controller (100) adjusts the opening of the air supply passage (41) and the air exhaust passage (42) of the ventilation device (40), and further adjusts the ventilation volume of the ventilation device (40). The controller (100) controls the air pump (53) and the PSA device (54) of the adjustment device (50).

[0072] (5-3) Operation section As shown in FIG. 3, the container refrigeration unit (10) has an operation unit (110). The operation unit (110) is configured with, for example, a touch panel, a remote controller, a switch, or the like provided in the container refrigeration unit (10). The operation unit (110) may be a communication terminal connected to the container refrigeration unit (10) via a network. A user can operate the operation unit (110) to switch the operation mode of the container refrigeration unit (10) or change the set values ​​of each operation mode. The set values ​​include a target value for the temperature of the inside air, a target value for the oxygen concentration of the inside air, and a target value for the carbon dioxide concentration of the inside air.

[0073] (5-4) Notification Department As shown in FIG. 3, the container refrigeration system (10) includes an alarm unit (120). The alarm unit (120) notifies a user of predetermined information. The predetermined information includes first information indicating that refrigerant has leaked from the refrigerant circuit (R). The alarm unit (120) includes a display, a speaker, or a communication device that transmits the first information to another terminal. When the controller (100) determines that refrigerant has leaked, the alarm unit (120) issues a notification of the first information.

[0074] (6) Driving behavior (6-1) Cooling operation The container refrigeration unit (10) performs a cooling operation, which is initiated by a user or the like operating the operation unit (110).

[0075] During the cooling operation, a refrigeration cycle is performed in which refrigerant compressed by the compressor (25) is condensed in the external heat exchanger (26), reduced in pressure by the expansion valve (31), and evaporated in the internal heat exchanger (29). Air flowing out from the internal space (3) into the internal passage (16) is cooled by the internal heat exchanger (29) functioning as an evaporator. The cooled air is sent to the internal space (3).

[0076] In the cooling operation, the controller (100) controls the compressor (25) so that the temperature of the internal air reaches a target temperature. When the temperature of the internal air reaches the target temperature (thermo-off temperature, e.g., −18° C.), the controller (100) stops the compressor (25). As a result, the internal heat exchanger (29) is essentially in a stopped state (thermo-off state). Thereafter, when the temperature of the internal air reaches a predetermined temperature (thermo-on temperature, e.g., −16° C.) higher than the target temperature, the controller (100) operates the compressor (25) to make the internal heat exchanger (29) function as an evaporator. The controller (100) controls the rotation speed of the compressor (25) to adjust the evaporation temperature of the internal heat exchanger (29). As a result, the temperature of the internal air is maintained within a predetermined target range.

[0077] (6-2) Adjustment operation The adjustment device (50) performs an adjustment operation to adjust the composition of the interior air in the interior space (3). The adjustment device (50) of this embodiment adjusts the oxygen concentration and carbon dioxide concentration of the interior air. The adjustment operation is performed simultaneously with the cooling operation described above. The adjustment operation includes a first adjustment operation and a second adjustment operation. The first adjustment operation is an operation in which nitrogen in the outside air is concentrated and then the nitrogen-concentrated air is supplied to the interior space (3). The second adjustment operation is an operation in which the outside air is supplied directly to the interior space (3). Below, the humidity control operation will be described taking as an example a case in which the control range of the oxygen concentration of the interior air is 4% to 6% and the control range of the carbon dioxide concentration of the interior air is 1% to 30%. The control values ​​of these control ranges are set values ​​set by the user operating the operation unit (110).

[0078] At the time when the loading of the container (1) with the target items such as fruits and vegetables and flowers is completed, the composition of the air inside the freezer is substantially the same as the composition of the atmosphere (nitrogen concentration: 78%, oxygen concentration: 21%, carbon dioxide concentration: 0.04%). Therefore, at this time, the controller (100) executes a first adjusting operation to reduce the oxygen concentration of the air inside the freezer. In the first adjusting operation, nitrogen-enriched air is supplied to the freezer space. As a result, the oxygen concentration of the air inside the freezer decreases.

[0079] When the oxygen concentration in the air inside the refrigerator reaches the upper limit (6%) of the control range, the controller (100) terminates the first adjusting operation of the adjusting device (50). As a result, the fruits, vegetables, and flowers in the refrigerator space (3) breathe, causing the oxygen concentration in the air inside the refrigerator to gradually decrease. At the same time, the carbon dioxide concentration in the air inside the refrigerator to gradually increase.

[0080] When the adjustment device (50) is stopped, if the carbon dioxide concentration of the internal air reaches the upper limit (30%) of the control range, the controller (100) causes the adjustment device (50) to perform the first adjustment operation. As a result, nitrogen-enriched air is supplied to the internal space (3), and the carbon dioxide concentration of the internal air decreases.

[0081] During the first adjusting operation of the adjusting device (50), when the carbon dioxide concentration of the inside air reaches the lower limit (1%) of the control range, the controller (100) terminates the first adjusting operation of the adjusting device (50). Furthermore, during the first adjusting operation of the adjusting device (50), when the oxygen concentration of the inside air reaches the lower limit (4%) of the control range, the controller (100) causes the adjusting device (50) to perform the second adjusting operation. Thereafter, when the oxygen concentration of the inside air reaches the upper limit (6%) of the control range, the adjusting device (50) terminates the second adjusting operation.

[0082] (7) Control for detecting refrigerant leaks If carbon dioxide leaks from the refrigerant circuit (R) into the interior space (3), it can have adverse effects on the human body, such as the user, and on objects in the interior space (3). In addition, the cooling capacity of the cooling unit (U) decreases due to the refrigerant leakage, impairing the temperature control of the objects. In this embodiment, the following control is performed to resolve such problems.

[0083] (7-1) Basic Control The basic control of refrigerant leakage will be described with reference to FIG. 5. In the following description, the carbon dioxide concentration (C) refers to the detected value of the carbon dioxide concentration in the air inside the refrigerator detected by the carbon dioxide sensor (63). The method for determining refrigerant leakage includes a first operation and a second operation. The first operation is an operation for determining refrigerant leakage based on the detected value of the carbon dioxide sensor (63). The second operation is an operation for determining refrigerant leakage based on the operating state of the refrigerant circuit (R). In the refrigerator space (3), the carbon dioxide concentration in the air inside the refrigerator increases due to respiration of fruits, vegetables, and flowers. Selective execution of the first operation and the second operation can prevent erroneous determination of refrigerant leakage due to this respiration. The following method for determining refrigerant leakage is performed while the cooling unit (U) is operating.

[0084] In step ST11, the controller (100) determines whether the carbon dioxide concentration (C) is greater than a first value (Cs1). The first value (Cs1) is an upper limit (e.g., 30%) of the control range of the carbon dioxide concentration in the adjustment device (50). If the carbon dioxide concentration (C) is greater than the first value (Cs1), in other words, if the carbon dioxide concentration (C) exceeds the control range of the adjustment device (50), there is an extremely high possibility that refrigerant is leaking from the refrigerant circuit (R). Therefore, in this case, in step ST18, the controller (100) causes the notification unit (120) to issue a first message. As a result, a user or the like can quickly learn that refrigerant has leaked from the refrigerant circuit (R) and can take predetermined measures.

[0085] Next, in step ST19, the controller (100) controls the ventilation device (40) to perform a ventilation operation. Specifically, the controller (100) controls the opening / closing cover (45) of the ventilation device (40) to open the air supply passage (41) and the exhaust passage (42). The controller (100) operates the internal fan (30). As a result, outside air is supplied to the internal space (3) through the air supply passage (41). At the same time, the outside air is discharged to the outside of the internal space (3) through the exhaust passage (42). As a result, the carbon dioxide concentration in the internal space (3) can be reduced quickly. In the ventilation operation of step ST19, the ventilation device (40) preferably opens the air supply passage (41) and the exhaust passage (42) to their maximum extents. In addition, the internal fan (30) preferably operates at its maximum airflow rate. This allows the carbon dioxide concentration in the internal air to be reduced more quickly.

[0086] If the carbon dioxide concentration (C) is equal to or less than the first value (Cs1) in step ST11, the process proceeds to step ST12. In step ST12, the controller (100) determines whether a first condition is met, which indicates the presence of fruits, vegetables, or flowers in the internal space (3). This is because fruits, vegetables, and flowers emit carbon dioxide as they breathe, and the presence or absence of these plants affects the determination of refrigerant leakage. The first condition will be described in detail later.

[0087] If it is determined that no fruits, vegetables, or flowers are present (NO in step ST12), the process proceeds to step ST17. In step ST17, a first operation is performed. Specifically, in step ST17, the controller (100) determines whether the carbon dioxide concentration (C) is greater than a second value (Cs2). The second value (Cs2) is a predetermined value that is smaller than the first value (Cs1) and greater than the carbon dioxide concentration in the atmosphere (e.g., 0.04%). The second value (Cs2) is set to, for example, 0.1%. If the carbon dioxide concentration (C) is relatively high when no fruits, vegetables, or flowers are present in the interior space (3), there is a high possibility that refrigerant is leaking from the refrigerant circuit (R). Therefore, if the condition of step ST17 is met, operations related to measures to prevent refrigerant leakage are performed in steps ST18 and ST19.

[0088] If it is determined in step ST12 that there are fruits, vegetables, or flowers, the process proceeds to step ST13. In step ST13, the controller (100) determines whether the adjustment device (50) is operating. Specifically, the controller (100) determines, for example, whether the adjustment device (50) is performing the first adjustment operation or the second adjustment operation. If the condition of step ST13 is met, the process proceeds to step ST14.

[0089] In step ST14, a second operation is performed. In step ST14, the controller (100) determines whether or not there is refrigerant leakage based on the operating state of the refrigerant circuit (R). Specifically, the controller (100) determines whether or not there is refrigerant leakage based on, for example, the pressure of the refrigerant in the refrigerant circuit (R), the temperature of the refrigerant in the refrigerant circuit (R), or the opening of the expansion valve (31).

[0090] The refrigerant pressure includes the high-pressure and low-pressure pressures of the refrigerant circuit (R). The refrigerant pressure is detected by a pressure sensor. If refrigerant leaks from the refrigerant circuit (R), these pressures will drop. Therefore, a refrigerant leak can be determined based on the refrigerant pressure or a change in the refrigerant pressure.

[0091] The temperature of the refrigerant includes the condensation temperature (heat release temperature) and evaporation temperature of the refrigerant circuit (R). The temperature of the refrigerant is detected by a temperature sensor. If refrigerant leaks from the refrigerant circuit (R), the refrigerant temperature changes suddenly. Therefore, a refrigerant leak can be determined based on the refrigerant temperature or a change in the refrigerant temperature.

[0092] The controller (100) controls the opening degree of the expansion valve (31) based on the suction superheat degree. When refrigerant leaks from the refrigerant circuit (R), the suction superheat degree tends to increase, and the opening degree of the expansion valve (31) tends to increase. Therefore, refrigerant leakage can be determined based on the opening degree of the expansion valve (31) or a change in the opening degree of the expansion valve (31).

[0093] In the second operation, the controller (100) may determine refrigerant leakage based on the operating conditions of other refrigerant circuits (R), such as the degree of subcooling, the degree of suction superheat, the degree of discharge superheat, and the rotation speed of the compressor (25).

[0094] If it is determined in step ST14 that refrigerant has leaked, then in steps ST18 and ST19, actions related to measures to prevent refrigerant leakage are carried out.

[0095] If the condition of step ST13 is not satisfied, in other words, if it is determined that the adjustment device (50) is stopped, the process proceeds to step ST15. In step ST15, the second operation is performed, as in step ST14. If it is determined in step ST15 based on the operating state of the refrigerant circuit (R) that refrigerant has leaked, operations related to measures to prevent refrigerant leakage are performed in steps ST18 and ST19.

[0096] If the condition of step ST15 is not satisfied, in step ST16, the controller (100) determines whether or not the rate of increase of the carbon dioxide concentration (C) is greater than a predetermined value α. When refrigerant suddenly leaks from the refrigerant circuit (R), it may not be possible to quickly determine the refrigerant leakage based solely on the operating state of the refrigerant circuit (R). This is because an index related to the operating state of the refrigerant circuit (R) is an index that indirectly indicates refrigerant leakage and has a lower responsiveness for detecting refrigerant leakage than the carbon dioxide sensor (63). Therefore, in step ST16, the controller (100) determines the refrigerant leakage on the condition that the rate of increase of the carbon dioxide concentration (C) is greater than a predetermined value α. If the condition of step ST16 is satisfied, operations related to measures against refrigerant leakage are executed in steps ST18 and ST19. Therefore, if refrigerant suddenly leaks from the refrigerant circuit (R), it is possible to quickly detect this and take predetermined measures.

[0097] (7-2) Determining the presence or absence of fruits, vegetables, and flowers In the above-described step ST12, the controller (100) determines whether or not a first condition is satisfied, which indicates that fruits, vegetables, or flowers are present in the internal space (3). The details of the determination of the first condition will be described in detail with reference to FIG.

[0098] In step ST31, the controller (100) determines whether the adjustment device (50) is operating. If the adjustment device (50) is performing an adjustment operation, the process proceeds to step ST35, where the controller (100) determines that fruits, vegetables, or flowers are present in the internal space (3), i.e., the first condition is met. This is because the adjustment device (50) operates to maintain the freshness of the fruits, vegetables, or flowers in the internal space (3), and is not normally operated when no fruits, vegetables, or flowers are stored.

[0099] If the condition of step ST31 is not met, in step ST32, the controller (100) checks the input information. The input information is input to the controller (100) by the user operating the operation unit (110). The input information includes information on the type of object (storage item) to be stored in the internal space (3). The controller (100) refers to the input information and checks whether the type of the storage item is fruit, vegetables, or flowers. In other words, the controller (100) determines whether the information indicates that the storage item in the internal space (3) is fruit, vegetables, or flowers. If the type of storage item in the input information is fruit, vegetables, or flowers and the condition of step ST32 is met, the controller (100) determines in step ST35 that fruit, vegetables, or flowers are present in the internal space (3).

[0100] If the condition of step ST32 is not satisfied, in step ST33, the controller (100) determines whether or not the set temperature (Ts) of the inside air is higher than the first temperature (T1). The set temperature (Ts) of the inside air is a temperature set by a user or the like operating the operation unit (110) and corresponds to the target temperature of the inside air. The first temperature (T1) is a predetermined temperature lower than 0°C, for example, -10°C. The first temperature (T1) can be said to be the minimum temperature for maintaining the quality of fruits, vegetables, and flowers. When storing fruits, vegetables, and flowers in the inside space (3), the user normally does not set the target temperature of the inside air to be lower than the first temperature (-10°C). This is because if the inside temperature falls below -10°C, the quality of the fruits, vegetables, and flowers will be damaged. Therefore, in step ST33, if the set temperature (Ts) of the inside air is equal to or lower than the first temperature (T1) (NO in step ST33), the process proceeds to step ST36, and the controller (100) determines that no fruits, vegetables, or flowers are present in the inside space (3).

[0101] If the set temperature (Ts) of the internal air is higher than the first temperature (T1) in step ST33, the controller (100) determines in step ST34 whether the rate of decrease in the oxygen concentration in the internal space (3) is higher than a predetermined value β. The oxygen concentration is detected by the oxygen sensor (64). If fruits, vegetables, or flowers are present in the internal space (3), the fruits, vegetables, or flowers consume oxygen in the internal space (3), causing the oxygen concentration to decrease. Compared to the carbon dioxide concentration, the oxygen concentration in the internal space (3) is not significantly affected by refrigerant leakage. Therefore, if the condition in step ST34 is met, the controller (100) proceeds to step ST35, where it determines that fruits, vegetables, or flowers are present in the internal space (3). If the condition in step ST34 is not met, the controller (100) proceeds to step ST36, where it determines that no fruits, vegetables, or flowers are present in the internal space (3).

[0102] (7-3) Control when container refrigeration unit is turned on Control when the container refrigeration unit (10) is switched from the OFF state to the ON state will be described. Here, the "OFF state" means a state in which power is not supplied to the container refrigeration unit (10). For example, when the container (1) is in a repair workshop and no object is stored in the container (1), the container refrigeration unit (10) is in the OFF state. Here, the "ON state" means a state in which power is supplied to the container refrigeration unit (10). For example, when the container (1) is on board a container ship and power is supplied to the container refrigeration unit (10) from a power source on the container ship, the container refrigeration unit (10) is in the ON state.

[0103] As shown in Fig. 7, when the container refrigeration unit (10) is switched from an OFF state to an ON state in step ST51, the controller (100) operates the internal fan (30) in step ST52. This circulates the internal air in the internal space (3). The airflow rate of the internal fan (30) is preferably the maximum.

[0104] Next, in step ST53, the controller (100) determines whether the carbon dioxide concentration (C) is greater than the third value (Cs3). At this time, the internal fan (30) is in operation, so that if refrigerant is leaking from the refrigerant circuit (R), the carbon dioxide concentration can be detected promptly. More specifically, carbon dioxide has a higher density than air and is likely to accumulate in the lower part of the internal space (3). This may delay the detection of refrigerant leakage by the carbon dioxide sensor (63). In contrast, by operating the internal fan (30), the carbon dioxide in the lower part of the internal space (3) can be agitated, and this carbon dioxide can be quickly sent to the periphery of the carbon dioxide sensor (63). This allows refrigerant leakage to be detected promptly.

[0105] If the condition of step ST53 is met, in step ST54, the controller (100) causes the notification unit (120) to issue the first information. Then, in step ST55, the controller (100) causes the ventilation device (40) to perform the ventilation operation.

[0106] As described above, in this embodiment, when the container refrigeration unit (10) is switched from the OFF state to the ON state, the controller (100) operates the internal fan (30) and determines whether or not there is a refrigerant leak based on the detected value of the carbon dioxide sensor (63). Therefore, if there is a refrigerant leak when the container refrigeration unit (10) is in the OFF state, this can be detected as early as possible.

[0107] (8) Features The interior space (3) of the container refrigeration unit (10) may contain objects that consume oxygen to breathe, such as fruits, vegetables, and flowers. When these objects breathe, the carbon dioxide concentration increases. Therefore, there is a possibility that a refrigerant leak may be erroneously determined based on the sensor detection value, even when there is no refrigerant leak.

[0108] To avoid such erroneous determination, it is conceivable to determine a refrigerant leak based on the operating state of the refrigerant circuit (R). However, since the operating state of the refrigerant circuit (R) is not a method for directly determining a carbon dioxide refrigerant leak, there is a possibility that a refrigerant leak cannot be determined promptly. Therefore, if the determination of a refrigerant leak is delayed, the user may be affected by the carbon dioxide in the interior space (3), or the cooling capacity of the refrigerant circuit (R) may be reduced, resulting in a deterioration in the quality of the object. This embodiment solves this problem.

[0109] (8-1) The controller (100) selectively executes a first operation for determining whether a refrigerant leaks based on the detection value of the sensor (63) and a second operation for determining whether a refrigerant leaks based on the operating state of the refrigerant circuit (R). In the second operation, the controller (100) determines whether a refrigerant leaks based on the operating state of the refrigerant circuit (R), and is therefore not affected by the respiration of the fruits, vegetables, or flowers. By executing the second operation, it is possible to determine whether a refrigerant leaks without being affected by the respiration of the fruits, vegetables, or flowers. The first operation directly detects whether a refrigerant leaks, and therefore it is possible to quickly determine whether a refrigerant leaks. By selectively executing these two operations, it is possible to quickly determine whether a refrigerant leaks while suppressing erroneous determinations of a refrigerant leak. As a result, it is possible to prevent the user from being affected by carbon dioxide in the interior space (3) and to prevent a decrease in the cooling capacity of the refrigerant circuit (R).

[0110] (8-2) In step ST12, the controller (100) determines whether a first condition indicating the presence of fruit, vegetables, or flowers in the internal space (3) is met. When the first condition is met, the controller (100) performs a second operation, such as in steps ST14 or ST15. When the first condition is not met, the controller (100) performs a first operation, such as in step ST17. Therefore, when fruit, vegetables, or flowers are present in the internal space (3), the controller (100) can determine the presence of a refrigerant leak by the second operation without being affected by breathing. When no fruit, vegetables, or flowers are present in the internal space (3), the controller (100) can quickly determine the presence of a refrigerant leak based on the detection value of the carbon dioxide sensor (63).

[0111] (8-3) The container refrigeration system (10) includes an adjustment device (50) that performs an adjustment operation to adjust the composition of air in the interior space (3). The controller (100) determines that refrigerant has leaked when a second condition is met in which the detected value of the sensor (63) is greater than a control range of the carbon dioxide concentration in the interior space (3) in the adjustment operation.

[0112] Therefore, when the carbon dioxide concentration in the internal space (3) is clearly high, it is possible to quickly determine whether or not there is a refrigerant leak.

[0113] (8-4) The first condition includes a condition that the regulator (50) is in the regulation operation (step ST31). This is because, when the regulator (50) is in the regulation operation, there is a high possibility that fruits, vegetables, or flowers are present in the internal space (3).

[0114] The first condition includes a condition that the set temperature of the air in the internal space (3) is higher than a predetermined temperature that is lower than 0°C (step ST33). This is because, when fruits, vegetables, or flowers are stored in the internal space (3), it is highly likely that the set temperature will be relatively high in order to maintain the quality of these items.

[0115] The first condition includes a condition that the rate of decrease of the oxygen concentration in the internal space (3) is greater than a predetermined value β (step ST34). This is because, when fruits, vegetables, or flowers are present in the internal space (3), they consume oxygen in the internal space (3), and the rate of decrease of the oxygen concentration becomes large.

[0116] The first condition includes a condition that information indicating that the stored items in the internal space (3) are fruits, vegetables, or flowers has been input to the controller (100) (step ST32). When this information is input, fruits, vegetables, or flowers are normally stored in the internal space (3).

[0117] In this embodiment, by using such a first condition, it is possible to accurately determine with a simple configuration whether or not fruits, vegetables, or flowers are present in the interior space (3).

[0118] (8-5) When the adjustment device (50) is not performing an adjustment operation, if the rate of increase in the detected value of the sensor (63) is greater than a predetermined value, the controller (100) determines that refrigerant has leaked (YES in step ST16). Therefore, if carbon dioxide is suddenly leaking from the refrigerant circuit (R), this can be quickly determined.

[0119] (8-6) When the container refrigeration unit (10) is switched from an OFF state to an ON state, the controller (100) operates the internal fan (30) and determines whether or not there is a refrigerant leak based on the detected value of the sensor (63). Therefore, if there is a refrigerant leak when the container refrigeration unit (10) is in the OFF state, this can be determined promptly.

[0120] (8-7) In the second operation, the controller (100) determines whether or not there is a refrigerant leak based on the pressure or temperature of the refrigerant in the refrigerant circuit (R) or the opening of the expansion valve (31) serving as an expansion mechanism. These determinations enable the controller (100) to determine whether or not there is a refrigerant leak, without being affected by breathing.

[0121] (8-9) When the controller (100) determines that a refrigerant leak has occurred, it operates the ventilation device (40). Therefore, when a refrigerant leak has occurred, the carbon dioxide concentration in the internal space (3) can be quickly reduced. As a result, the influence of carbon dioxide in the internal space (3) on the user can be reduced.

[0122] (9) Variations The above-described embodiment may be modified as follows: The following describes the differences from the above-described embodiment.

[0123] (9-1) Variation 1 In the first modification, the first condition indicating that fruits or vegetables or flowers are present in the interior space (3) includes at least one of the following conditions A to C.

[0124] Condition A is a condition in which the ethylene concentration is equal to or greater than a predetermined value. The ethylene concentration is detected by an ethylene sensor disposed in the interior space (3). If fruits, vegetables, or flowers are present in the interior space, they generate ethylene, causing the ethylene concentration to increase. Therefore, the controller (100) determines that fruits, vegetables, or flowers are present in the interior space (3) when the ethylene concentration is equal to or greater than the predetermined value.

[0125] Condition B is a condition in which the amount of moisture generated in the internal space (3) is equal to or greater than a predetermined value. When fruits, vegetables, or flowers are present in the internal space (3), moisture is generated as they respire. By setting the amount of moisture equal to or greater than a predetermined value as the first condition, the presence of fruits, vegetables, or flowers can be determined. The controller (100) estimates the amount of moisture generated in the internal space (3) based on the amount of water drained from a drain pan that receives water generated in the internal space (3). The controller (100) may estimate this amount of moisture based on the humidity of the air inside the internal space (3).

[0126] Condition C indicates an increase in the cooling load of the interior space (3). If fruits, vegetables, or flowers are present in the interior space (3), the cooling load increases due to the heat generated by their respiration. By setting the increase in cooling load as the first condition, the presence of fruits, vegetables, or flowers can be determined. The increase in cooling load is obtained, for example, based on data including the current output of the cooling unit (U) and a previously determined output of the cooling unit (U). The output here refers to the rotation speed of the compressor (25) and the power consumption of the cooling unit (U). For example, the data includes outputs corresponding to the outside air temperature, the inside temperature, or the set temperature. The controller (100) calculates a comparison output based on the current outside air temperature, the inside temperature, and the set temperature. The controller (100) calculates the increase in cooling load due to the heat generated by respiration, for example, from the difference between the current output of the cooling unit (U) and the comparison output.

[0127] (9-2) Variation 2 The container refrigeration unit (10) of Modification 2 does not have the adjustment unit (50) of Embodiment 1. In other words, the container refrigeration unit (10) does not have the function of adjusting the composition of the interior air in the interior space (3).

[0128] The controller (100) of Modification 2 executes the refrigerant leakage determination method shown in FIG. 8. In Modification 2, if the first condition is not met in step ST61, a first action based on the detected value of carbon dioxide is performed in step ST66. If the first condition is met in step ST61, a second action based on the operating state of the refrigerant circuit (R) is performed in step ST62. If it is determined in step ST62 that refrigerant has leaked, the actions related to the measures in steps ST63 and ST64 are executed. If it is determined in step ST62 that refrigerant has not leaked, a determination similar to that in step ST16 of the embodiment is made in step ST65. The first condition in Modification 2 does not include the condition in step ST31 of the embodiment. The effects of these controls in Modification 2 are the same as those in the embodiment.

[0129] (9-3) Variation 3 The container refrigeration system (10) of the third modification controls the adjustment device (50) instead of the ventilation device (40) in the ventilation operation of step ST19 of FIG. 5 and step ST55 of FIG. 7. Specifically, in these processes, the controller (100) controls the adjustment device (50) so that outside air is introduced into the interior space (3). In this case, the controller (100) preferably controls the adjustment device (50) so that the interior air is discharged to the outside. Thus, in the third modification, the adjustment device (50) is an example of a ventilation unit.

[0130] (10) Other embodiments The above-described embodiment and each of the modifications may be configured as follows.

[0131] The refrigeration unit may not be a container refrigeration unit, but may be a stationary refrigeration unit for cooling the interior of a warehouse, etc. The container (1) does not have to be for marine transportation, but may be for land transportation, carried by a vehicle such as a trailer or by rail.

[0132] The controller (100) may be physically separated from the container refrigeration system (10). In this case, for example, the controller (100) constitutes a server device connected to the cooling unit (U) via a network. In this case, the refrigeration system constitutes a refrigeration system having the cooling unit (U) and the controller (100). The controller (100) may be provided in the adjustment device (50) or in the operation unit (110).

[0133] The ventilation unit may have only an air supply function of supplying outside air from the outside space (5) to the inside space (3), and may not have an exhaust function. The fan of the ventilation device (40) may be a fan dedicated to ventilation, different from the inside fan.

[0134] The expansion mechanism does not have to be an expansion valve, but may be a capillary tube or an expander. (11) Other explanations The refrigerant leakage determination methods according to the above-described embodiments, modifications, and other embodiments include any of the steps described above. The controller (100) according to the above-described embodiments, modifications, and other embodiments includes a program for causing a computer to execute these steps, and a storage device or storage medium for storing the program.

[0135] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0136] The terms "first," "second," "third," etc. mentioned above are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0137] As described above, the present disclosure is useful for container refrigeration systems. [Explanation of symbols]

[0138] 3. Interior space 10 Container refrigeration equipment (refrigeration equipment) 25 Compressor 26 External heat exchanger (radiator) 29 Internal heat exchanger (evaporator) 30 Interior fan 31 Expansion valve (expansion mechanism) 40 Ventilation equipment (ventilation unit) 50 Adjustment device (ventilation unit) 63 Carbon dioxide sensor (sensor) 100 Controller

Claims

1. a refrigerant circuit (R) having a compressor (25), a radiator (26), an expansion mechanism (31), and an evaporator (29), and performing a refrigeration cycle using carbon dioxide as a refrigerant; a sensor (63) for detecting a carbon dioxide concentration in the interior space (3) cooled by the evaporator (29); a controller (100); The controller (100) a first operation of determining whether or not there is a leakage of the refrigerant based on a detection value of the sensor (63); a second operation of determining whether or not there is a leakage of the refrigerant based on an operating state of the refrigerant circuit (R); The controller (100) execute a process of determining whether a first condition indicating the presence of fruits, vegetables, or flowers in the storage space (3) is satisfied; If the first condition is satisfied as a result of the processing, the second action is performed; If the first condition is not satisfied as a result of the processing, the first action is performed. Refrigeration equipment.

2. The controller (100) In the first operation, when the carbon dioxide concentration detected by the sensor (63) is greater than a first value, it is determined that refrigerant has leaked; If the first condition is met as a result of the processing, the first action is not performed and the second action is performed. The refrigeration system of claim 1.

3. The controller (100) If the first condition is not met as a result of the processing, the second action is not performed and the first action is performed. The refrigeration system of claim 1.

4. The air conditioner (50) is provided with an adjusting device (50) that adjusts the composition of the air in the interior space (3). The refrigeration system of claim 1.

5. The controller (100) determines that refrigerant has leaked when a second condition is met in which the detected value of the sensor (63) is greater than a control range of the carbon dioxide concentration in the internal space (3) in the adjustment operation.

5. The refrigeration system of claim 4.

6. The first condition includes a condition that the adjusting device (50) is in the adjusting operation.

5. The refrigeration system of claim 4.

7. The first condition includes a condition that the set temperature of the air in the internal space (3) is higher than a predetermined temperature lower than 0°C. The refrigeration device according to any one of claims 1 to 6.

8. The first condition includes a condition that the rate of decrease of the oxygen concentration in the internal space (3) is greater than a predetermined value. The refrigeration device according to any one of claims 1 to 6.

9. The first condition is A condition in which information indicating that the items stored in the interior space (3) are fruits, vegetables, or flowers is input to the controller (100), or The condition that the ethylene concentration in the interior space (3) is equal to or higher than a predetermined value, or The condition that the amount of moisture generated in the interior space (3) is equal to or greater than a predetermined value, or A condition indicating that the cooling load of the interior space (3) has increased is included. The refrigeration device according to any one of claims 1 to 6.

10. The controller (100) When the adjusting device (50) is not performing the adjusting operation, if the rate of increase in the detected value of the sensor (63) is greater than a predetermined value, it is determined that refrigerant has leaked. The refrigeration device according to any one of claims 4 to 6.

11. an internal fan (30) for transporting air in the internal space (3); When the refrigeration system (10) is switched from an OFF state to an ON state, the controller (100) operates the internal fan (30) and determines whether or not there is a refrigerant leak based on the detected value of the sensor (63). The refrigeration device according to any one of claims 1 to 6.

12. In the second operation, the controller (100) determines whether or not there is a refrigerant leak based on the pressure of the refrigerant in the refrigerant circuit (R), the temperature of the refrigerant in the refrigerant circuit (R), or the opening of an expansion valve (31) serving as an expansion mechanism. The refrigeration device according to any one of claims 1 to 6.

13. a ventilation unit (40, 50) for ventilating the interior space (3), When the controller (100) determines that a refrigerant leak has occurred, the controller (100) operates the ventilation unit (40, 50). The refrigeration device according to any one of claims 1 to 6.

14. A method for determining refrigerant leakage in a refrigeration system including a refrigerant circuit (R) having a compressor (25), a radiator (26), an expansion mechanism (31), and an evaporator (29) and performing a refrigeration cycle using carbon dioxide as a refrigerant, a sensor (63) for detecting a carbon dioxide concentration in an internal space (3) cooled by the evaporator (29), and a controller (100), The controller (100) execute a process of determining whether a first condition indicating the presence of fruits, vegetables, or flowers in the storage space (3) is satisfied; If the first condition is satisfied as a result of the processing, a second operation is performed to determine whether or not there is a leakage of the refrigerant based on an operating state of the refrigerant circuit (R); If the first condition is not satisfied as a result of the process, a first operation is performed to determine whether or not there is a refrigerant leak based on the detected value of the sensor (63). Refrigerant leak detection method.

15. A program for causing a computer to execute the refrigerant leakage determination method according to claim 14.

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