JP6739664B2 - Refrigeration air conditioner and control device - Google Patents

Description

The present invention relates to a control device that determines whether or not a refrigerant leaks from a refrigerant circuit, and a refrigerating and air-conditioning apparatus including the control device.

Patent Document 1 discloses an example of refrigerant leak detection performed by a conventional air conditioner. In Patent Document 1, it is assumed that there is a required amount of refrigerant in the refrigeration circuit, and a state in which the difference between the state amount in the theoretical refrigeration cycle obtained by the heat load and the actually measured state amount is a predetermined value or more for a certain period. It is described that when it continues, it is judged that the refrigerant is insufficient. Patent Document 1 discloses an evaporator inlet temperature as a specific example of the state quantity.

Japanese Patent Laid-Open No. 5-99542

The detection of refrigerant leakage disclosed in Patent Document 1 is to detect whether or not the refrigerant amount is insufficient in the entire refrigeration cycle based on a change in the state quantity, and is not to identify the location where the refrigerant leakage occurs. Therefore, it is necessary for the on-site worker to perform a check operation for identifying the refrigerant leakage portion before starting the repair operation of the refrigerant circuit.

The present invention has been made to solve the above problems, and provides a refrigerating and air-conditioning apparatus and a control apparatus that can specify a portion where a refrigerant leak has occurred.

Refrigeration air conditioner according to the present invention, a compressor, a condenser, an expansion unit, an evaporator and an accumulator are connected by a pipe, a refrigerant circuit in which a non-azeotropic mixed refrigerant in which plural kinds of refrigerants having different boiling points are mixed is circulated. , An inflow temperature sensor for measuring the temperature of the non-azeotropic mixed refrigerant flowing into the evaporator, and controlling the refrigerant circuit so that the pressure of the non-azeotropic mixed refrigerant flowing into the evaporator becomes a set pressure. in inspection mode, said calculating a temperature difference between the temperature of the inlet temperature sensor and the saturation temperature is measured at the set pressure, and the temperature difference with a threshold value that is set based different boiling points of the plurality of kinds of refrigerants And a control device that determines whether or not the non-azeotropic mixed refrigerant is leaking by comparison.

According to the present invention, by detecting the occurrence of refrigerant leakage in the region where the non-azeotropic mixed refrigerant flows in the gas-liquid two-phase state, the section from the expansion section to the outlet of the evaporator, or the condenser, the refrigerant The location of the leak can be identified.

It is a refrigerant circuit diagram showing an example of the refrigerating and air-conditioning system concerning Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a configuration example of a control device shown in FIG. 1. It is a table showing the boiling point and composition ratio of the refrigerant when the non-azeotropic mixed refrigerant is R407C. FIG. 5 is a ph diagram showing the state of the refrigerant in the inspection mode according to the first embodiment of the present invention. 4 is a table showing temperatures at points A to C shown in FIG. 4 when R32 and R125 among the three kinds of refrigerants constituting the non-azeotropic mixed refrigerant shown in FIG. 3 leak. It is a flowchart which shows operation|movement of the refrigerating air-conditioning apparatus which concerns on Embodiment 1 of this invention.

Embodiment 1.
The refrigerating and air-conditioning apparatus according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a refrigerant circuit diagram showing an example of a refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention. The refrigerating and air-conditioning apparatus 100 according to the first embodiment is an apparatus that cools a cooling target such as a refrigerator. As shown in FIG. 1, the refrigeration air conditioning system 100 includes a refrigerant circuit 10, a condensation temperature sensor 21, an expansion part inlet temperature sensor 22, an inflow pressure sensor 23, an inflow temperature sensor 24, and a control device 50. .. The refrigerant circuit 10 is a non-azeotropic mixed refrigerant in which a compressor 11, a condenser 12, an expansion unit 13, an evaporator 14, an accumulator 15 and a liquid receiver 16 are connected by piping, and a plurality of kinds of refrigerants having different boiling points are mixed. Is a circulating structure.

The compressor 11 draws in and compresses the low-temperature low-pressure non-azeotropic mixed refrigerant and discharges the high-temperature high-pressure non-azeotropic mixed refrigerant. The compressor 11 is, for example, an inverter compressor whose capacity can be controlled. The condenser 12 is a heat exchanger for exchanging heat between the outdoor air and the non-azeotropic mixed refrigerant. The expansion section 13 is a pressure reducing valve or an expansion valve that decompresses and expands the non-azeotropic mixed refrigerant. The expansion section 13 is, for example, an electronic expansion valve whose opening can be adjusted. The evaporator 14 is a heat exchanger that cools the cooling chamber and exchanges heat between the air in the cooling chamber and the non-azeotropic mixed refrigerant.

The accumulator 15 and the liquid receiver 16 separate the gas refrigerant and the liquid refrigerant. The outlet pipe of the liquid receiver 16 is configured so that the liquid-phase refrigerant flows out unless the liquid receiver 16 is emptied. The liquid receiver 16 stores, of the non-azeotropic mixed refrigerant that circulates in the refrigerant circuit 10, an excess refrigerant that is generated due to a temperature change around the device. The accumulator 15 stores the liquid-phase refrigerant when the liquid-phase refrigerant is transiently returned from the evaporator 14 such as the liquid back operation. In the first embodiment, the case where the liquid receiver 16 is provided in the refrigerating and air-conditioning apparatus 100 as shown in FIG. 1 will be described, but the liquid receiver 16 may not be provided.

The condensation temperature sensor 21 is provided on the refrigerant outlet side of the condenser 12. The condensation temperature sensor 21 measures the condensation temperature Ctemp of the non-azeotropic mixed refrigerant flowing through the condenser 12. The expansion portion inlet temperature sensor 22 is provided on the refrigerant inlet side of the expansion portion 13. The expansion part inlet temperature sensor 22 measures the pre-expansion temperature of the non-azeotropic mixed refrigerant flowing into the expansion part 13. The inflow pressure sensor 23 is provided on the refrigerant inlet side of the evaporator 14. The inflow pressure sensor 23 measures the pressure PL of the non-azeotropic mixed refrigerant flowing into the evaporator 14. The inflow temperature sensor 24 is provided on the refrigerant inlet side of the evaporator 14. The inflow temperature sensor 24 measures the temperature of the non-azeotropic mixed refrigerant flowing into the evaporator 14.

The control device 50 controls the operation of the refrigerating and air conditioning device 100 based on the measured values of the pressure and temperature of each part in the refrigerant circuit 10 and various set values including the set temperature of the air conditioning target space. The control device 50 is, for example, a microcomputer. FIG. 2 is a block diagram showing a configuration example of the control device shown in FIG. The control device 50 has a refrigeration cycle control means 51, an inspection mode execution means 52, a calculation means 53, and a determination means 54. Although not shown, the control device 50 has a memory that stores a program and a CPU (Central Processing Unit) that executes processing in accordance with the program. When the CPU executes the program, the refrigeration cycle control means 51, the inspection mode execution means 52, the calculation means 53, and the determination means 54 shown in FIG. A memory (not shown) stores various information used for setting temperature, controlling the refrigerating and air-conditioning apparatus 100, and determining refrigerant leakage.

Although the refrigeration air conditioner 100 is provided with a temperature sensor that measures the temperature of the outdoor air and a temperature sensor that measures the temperature of the air in the cooling chamber, these temperature sensors are omitted from the drawing. There is. Although not shown in FIG. 1, the evaporator 14 may be provided with a fan for supplying air in the cooling chamber, and the condenser 12 may be provided with a fan for supplying outdoor air. In this case, the controller 50 may control the operating frequencies of these fans. Further, the refrigerating and air-conditioning apparatus 100 may include a flow path switching unit that switches the flow direction of the non-azeotropic mixed refrigerant flowing in the refrigerant circuit 10. In this case, the refrigeration air conditioning system 100 can perform both the cooling operation and the heating operation. The air conditioning target space of the refrigerating and air conditioning apparatus 100 is not limited to the cooling room.

Next, the cooling operation of the refrigerating and air-conditioning apparatus 100 will be described. The refrigerant sucked into the compressor 11 is compressed by the compressor 11 and is discharged from the compressor 11 in a high temperature and high pressure gas state. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the condenser 12. In the condenser 12, the high-temperature and high-pressure gas refrigerant is heat-exchanged with outdoor air to be condensed and liquefied. When the condensed refrigerant in the liquid state flows into the receiver 16, the excess refrigerant is stored in the receiver 16 and only the liquid refrigerant flows out from the receiver 16. When the liquid refrigerant flows into the expansion section 13, the liquid refrigerant is expanded and decompressed in the expansion section 13 to become a low-temperature low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the evaporator 14. In the evaporator 14, the gas-liquid two-phase refrigerant is heat-exchanged with the air in the cooling chamber to be evaporated and gasified. At this time, the cooling chamber is cooled. The low-temperature low-pressure gas-state refrigerant is sucked into the compressor 11.

FIG. 3 is a table showing the boiling points and composition ratios of the refrigerant when the non-azeotropic mixed refrigerant is R407C. In the first embodiment, the case where the non-azeotropic mixed refrigerant sealed in the refrigerant circuit 10 is R407C will be described. As shown in FIG. 3, R407C is a mixture of R32, R125, and R134a refrigerants. The boiling point of R32 is -51.7°C, the boiling point of R125 is -48.1°C, and the boiling point of R134a is -26.1°C. That is, R134a has the highest boiling point among the three types of refrigerants constituting R407C. The temperature difference between the boiling points of R32 and R125 is 3.6°C, whereas the temperature difference between the boiling points of R125 and R134a is 22.0°C. Focusing on the composition ratio, the sum of the composition ratios of R32 and R125 is 48%, which is almost equal to 52% of R134a.

When the refrigerant is the non-azeotropic mixed refrigerant shown in FIG. 3, inside the heat exchanger where the phase change of the refrigerant occurs, the three kinds of refrigerant start phase change at different timings. For example, inside the condenser 12, among the three types of refrigerant, R134a having the highest boiling point starts liquefying before R125 and R32. On the other hand, inside the evaporator 14, among the three kinds of refrigerants, R125 and R32 having a low boiling point start vaporizing before R134a. That is, the composition ratios of the three kinds of refrigerants are different from the values shown in FIG. 3 in the portion where the refrigerants are mixed in the gas-liquid two phase inside the heat exchanger. Specifically, in the gas-liquid two-phase liquid refrigerant, the composition ratio of R134a is more than 52%, and the total value of the composition ratios of R125 and R32 is less than 48%. In the gas-liquid two-phase gas refrigerant, the sum of the composition ratios of R125 and R32 is more than 48%, and the composition ratio of R134a is less than 52%.

Here, consider a case where a refrigerant leak occurs due to a crack in the heat transfer tube of the condenser 12 or the evaporator 14. In the refrigerant circuit 10, the part where the refrigerant is in the gas-liquid two-phase state is the condenser 12 and the section from the expansion part 13 to the evaporator 14. As described above, the distribution of each refrigerant in the mixed refrigerant differs depending on the phase state. Therefore, when a refrigerant leak occurs in a portion where the refrigerant is in a gas-liquid two-phase state, the composition of the refrigerant flowing in the refrigerant circuit 10 changes, and the composition changes greatly as the refrigerant leakage progresses. Specifically, when the cracked part is mainly the part where the vapor phase refrigerant flows, a large amount of R125 and R32 leaks, and the composition ratio of R134a becomes larger than the value shown in FIG. On the other hand, when the crack-occurring portion is mainly a portion where the liquid-phase refrigerant flows, a large amount of R134a leaks, and the composition ratio of R125 and R32 becomes larger than the value shown in FIG.

Next, the refrigerant leak determination performed by the control device 50 will be described. The refrigerating and air-conditioning apparatus 100 has a normal operation mode for air-conditioning the cooling chamber and an inspection mode for detecting refrigerant leakage. The inspection mode is a mode in which the control device 50 controls the refrigerant circuit 10 under an inspection condition in which the pressure PL in the evaporator 14 is kept at the set pressure in order to determine whether or not the refrigerant leaks.

The refrigeration cycle control means 51 and the inspection mode execution means 52 perform refrigeration based on the temperatures acquired from the condensation temperature sensor 21, the expansion part inlet temperature sensor 22 and the inflow temperature sensor 24 and the pressure PL acquired from the inflow pressure sensor 23. Understand the operating state of the air conditioner 100. In the normal operation mode, the refrigeration cycle control means 51 operates so that the air temperature in the cooling chamber reaches the set temperature, the operating frequency of the compressor 11, the cooling air flow rates of the evaporator 14 and the condenser 12, and the opening of the expansion section 13. Control the degree and.

The refrigeration cycle control means 51 and the inspection mode execution means 52 control the cooling air volume of the condenser 12 and the operating frequency of the compressor 11 according to the temperature of the outdoor air supplied to the condenser 12 and the magnitude of the cooling load. Thus, the pressure PH of the refrigerant in the condenser 12 is adjusted. Further, the refrigeration cycle control means 51 and the inspection mode execution means 52 adjust the pressure PL by controlling the operating frequency of the compressor 11, the cooling air flow rate of the evaporator 14, the opening degree of the expansion part 13, and the like, and the evaporator 14 is controlled. The superheat degree of the refrigerant outlet of is maintained at the set superheat degree.

The inspection mode executing means 52 executes the inspection mode under the condition that the refrigerating and air-conditioning apparatus 100 can be continuously operated for a relatively long time. For example, the inspection mode executing means 52 may prevent the compressor 11 from stopping due to thermo-off or the like until the state of the refrigeration cycle stabilizes, when the defrosting operation is completed or the actual temperature of the cooling chamber is the set temperature of the cooling chamber. When it is higher than the above, the inspection mode is executed. Specifically, when the evaporation temperature converted from the pressure of the non-azeotropic mixed refrigerant flowing through the evaporator 14 is higher than the set temperature of the cooling chamber, the inspection mode execution means 52 executes the inspection mode. In this case, since the thermostat does not turn off, the control device 50 can determine whether or not the refrigerant leaks by keeping the non-azeotropic mixed refrigerant circulating in the refrigerant circuit 10 in a stable state.

FIG. 4 is a ph diagram showing the state of the refrigerant in the inspection mode according to the first embodiment of the present invention. The vertical axis of FIG. 4 represents the pressure of the refrigerant [MPa], and the horizontal axis represents the specific enthalpy [kJ/kg]. When the inspection mode execution means 52 starts the inspection mode, it causes a short liquid back operation so that the liquid refrigerant stored in the liquid receiver 16 becomes empty, and then sets the pressure PL in the evaporator 14 to the set pressure. The refrigerant circuit 10 is controlled so as to satisfy the inspection condition maintained at. After the inspection mode executing means 52 stores the excess refrigerant in the accumulator 15, the non-azeotropic mixed refrigerant is circulated in the refrigerant circuit 10 so as to reduce the excess refrigerant in the accumulator 15, so that the composition ratio of the non-azeotropic mixed refrigerant is increased. The refrigerant circuit 10 is kept even in its entirety. This is to make it easier to detect a change in the composition ratio of the refrigerant when some kinds of the refrigerant leak out of the plurality of kinds of refrigerant more than other refrigerants.

As shown in FIG. 4, the non-azeotropic mixed refrigerant compressed by the compressor 11 is condensed by the condenser 12, passes through point A, and is further cooled to reach point B. Then, the non-azeotropic mixed refrigerant is decompressed by the expansion section 13 and reaches the point C. Then, the non-azeotropic mixed refrigerant is evaporated by the evaporator 14 and drawn into the compressor 11.

In addition to the pressure PL, the condensing temperature Ctemp and the supercooling degree SC may be included as the parameters of the inspection condition set by the inspection mode executing means 52. In this case, the inspection conditions include a condition that the condensation temperature Ctemp matches the target condensation temperature CTg and a condition that the supercooling degree SC matches the target supercooling degree SCg, in addition to the condition that the pressure PL matches the set pressure. .. The degree of supercooling SC is the degree of supercooling of the non-azeotropic mixed refrigerant flowing on the inlet side of the expansion section 13. The inspection mode execution means 52 obtains the supercooling degree SC by subtracting the pre-expansion temperature measured by the expansion part inlet temperature sensor 22 from the condensation temperature Ctemp measured by the condensation temperature sensor 21. The pressure PL matches the set pressure includes not only the case where the pressure PL completely matches the set pressure but also the case where these two values match within a certain allowable range. This is the same when the parameters of the inspection conditions are the supercooling degree SC and the condensing temperature Ctemp.

The inspection mode execution means 52 controls the refrigerant circuit 10 so that the condensing temperature Ctemp is stable at the target condensing temperature CTg, the supercooling degree SC is stable at the target supercooling degree SCg, and the pressure PL is stable at the set pressure. .. In the example shown in FIG. 4, the target condensing temperature CTg is 45° C., the target supercooling degree SCg is 5K, and the set pressure of the pressure PL is 0.3 MPa.

Here, the inspection mode execution means 52 supplies the operating frequency of the compressor 11 and the outdoor air to the condenser 12 so that the pressure PL in the inspection mode becomes higher than the pressure PL in the cooling operation in the normal operation mode. The output of the fan (not shown) is adjusted. In addition, the inspection mode execution unit 52 supplies the operating frequency of the compressor 11 and the outdoor air to the condenser 12 so that the condensation temperature Ctemp in the inspection mode becomes lower than the condensation temperature Ctemp in the cooling operation in the normal operation mode. Adjust the output of the fan to be supplied. As a result, the excess refrigerant decreases from the accumulator 15, the amount of the non-azeotropic mixed refrigerant circulating in the refrigerant circuit 10 increases, and the composition ratio of the non-azeotropic mixed refrigerant is kept uniform in the entire refrigerant circuit 10.

Of the parameters of the inspection condition, the pressure PH of the refrigerant in the condenser 12 may be used instead of the condensation temperature Ctemp. This is because the condensation temperature Ctemp can be calculated from the saturation temperature of the pressure PH.

The control device 50 determines the refrigerant based on the theoretical value of the saturation temperature obtained from the pressure PL of the non-azeotropic mixed refrigerant flowing into the evaporator 14 and the inlet temperature of the non-azeotropic mixed refrigerant flowing to the inlet side of the evaporator 14. Determine if there is a leak. Specifically, the calculation means 53 calculates the temperature difference TD between the saturation temperature at the pressure PL and the temperature measured by the inflow temperature sensor 24. The determination means 54 compares the temperature difference TD with the threshold value Tth. When the temperature difference TD is larger than the threshold value Tth, the determination unit 54 determines that there is a refrigerant leak. The threshold Tth is, for example, 1.5K.

Further, the determination unit 54 may continuously measure the time when the temperature difference TD exceeds the threshold value Tth, and may determine that there is a refrigerant leak when the measured time is equal to or longer than the set time. The set time is, for example, 5 minutes. Furthermore, the determination means 54 may output an alarm when it determines that there is a refrigerant leak.

FIG. 5 is a table showing the temperatures of points A to C shown in FIG. 4 when R32 and R125 among the three types of refrigerant constituting the non-azeotropic mixed refrigerant shown in FIG. 3 leak. When the non-azeotropic mixed refrigerant shown in FIG. 3 has no leakage, as shown in FIG. 5, the temperature at point A in FIG. 4 is 45° C., the temperature at point B is 40° C., and the temperature at point C is Is -15.9°C. The temperature of -15.9°C is a theoretical value of the saturation temperature of the pressure PL when the composition ratios of the three kinds of refrigerant are the values shown in Fig. 3.

In FIG. 5, when the assumed leakage rate of R32 and R125 increases, the composition ratio of R32 and R125 decreases, but conversely, the composition ratio of R134a increases. Then, as shown in FIG. 5, as the assumed rate of refrigerant leakage increases, the saturation temperature of the pressure PL that matches the set pressure increases. In the example shown in FIG. 5, the temperature difference at the point C is 1.7 K between when there is no refrigerant leakage and when the refrigerant leakage is assumed to be 10%.

The control device 50 compares the temperature difference TD with the threshold value Tth, and determines that there is refrigerant leakage because the temperature difference TD is 1.7K, which exceeds the threshold value Tth. In FIG. 5, the criterion for determining the presence/absence of refrigerant leakage is the case where the refrigerant leakage is assumed to be 10%.

As described above, in the condenser 12 or the evaporator 14, if refrigerant leakage mainly occurs at a portion where the gas-phase refrigerant flows, a large amount of R32 and R125 leaks. In this case, as the leakage of the refrigerant progresses, the composition ratio shown in FIG. 3 changes so that the composition ratio of R134a in all the refrigerant gradually increases. On the other hand, in the condenser 12 or the evaporator 14, if a refrigerant leak mainly occurs in a portion where the liquid-phase refrigerant flows, a large amount of R134a leaks. In this case, as the refrigerant leakage progresses, the composition ratios shown in FIG. 3 change such that the composition ratios of R32 and R125 in all the refrigerants gradually increase. As shown in FIG. 3, R134a has a higher boiling point than R32 and R125. Therefore, the saturation temperature when the pressure PL is a constant value changes as the composition ratio of the refrigerant changes. The example shown in FIG. 5 shows a case where refrigerant leakage mainly occurs at a portion where the vapor-phase refrigerant flows.

In the refrigeration air-conditioning apparatus 100 of Embodiment 1, the excess refrigerant is stored in the liquid receiver 16, and the refrigerant flowing out from the outlet of the liquid receiver 16 is in the liquid phase. Therefore, if the control device 50 controls the refrigerant at the refrigerant outlet of the evaporator 14 to become a superheated gas, the composition ratio of the refrigerant does not change except for the portion where the refrigerant exists in the gas-liquid two-phase state. In the first embodiment, this phenomenon can be used to identify the leaking portion of the refrigerant. The part where the refrigerant exists in the gas-liquid two-phase state is the inside of the condenser 12 and the section from the expansion part 13 to the outlet of the evaporator 14.

Next, the operation of the refrigerating and air-conditioning apparatus 100 will be described. FIG. 6 is a flowchart showing the operation of the refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention. Here, the case where the parameters of the inspection conditions are the condensing temperature Ctemp, the supercooling degree SC, and the pressure PL will be described. The inspection mode execution means 52 performs a defrosting operation before starting the inspection mode. The inspection mode execution means 52 determines whether or not the defrosting operation has ended (step ST1).

If the result of determination in step ST1 is that the defrosting operation has not ended, the inspection mode execution means 52 returns to the processing in step ST1. If the result of the determination in step ST1 is that the defrosting operation has ended, the inspection mode execution means 52 determines whether or not the thermo-on can be maintained in order to confirm whether or not the stable period required for the refrigerant leakage determination is secured. The determination is made (step ST2). If the result of determination in step ST2 is that the thermostat is off, the inspection mode execution means 52 returns to the processing in step ST2. If the result of determination in step ST2 is that the thermo-on can be maintained, the inspection mode execution means 52 shifts to the processing in step ST3.

In step ST3, the inspection mode execution means 52 does not show the values of the target condensation temperature CTg, the target supercooling degree SCg, and the set pressure as the target values of the condensation temperature Ctemp, the supercooling degree SC, and the pressure PL. Read from memory. Subsequently, the inspection mode execution means 52 determines whether or not the respective values of the condensing temperature Ctemp, the supercooling degree SC, and the pressure PL satisfy the inspection conditions in which the respective target values are within an allowable range (step ST4). The inspection mode execution means 52 operates the refrigerating and air-conditioning apparatus 100 until the inspection conditions are satisfied and the inspection conditions are stable.

When the inspection condition is not satisfied in step ST4, the control device 50 repeats the determination of step ST4 at regular time intervals. In step ST4, when the inspection condition is satisfied, the calculation means 53 calculates the temperature difference TD between the saturation temperature at the pressure PL and the temperature measured by the inflow temperature sensor 24. Then, the determination means 54 compares the temperature difference TD with the threshold value Tth and determines whether the temperature difference TD is larger than the threshold value Tth (step ST5).

If the result of determination in step ST5 is that the temperature difference TD is greater than the threshold value Tth, the determination means 54 determines that the non-azeotropic mixed refrigerant is leaking. On the other hand, when the temperature difference TD is equal to or less than the threshold value Tth in step ST5, the determination means 54 determines whether or not the thermostat is off (step ST6). If the result of the determination in step ST6 is that the thermostat is not off, the determination means 54 repeats the determinations in steps ST4 to ST6. In the determination of step ST6, when the thermostat is stopped due to the cooling in the inspection mode, the determination means 54 determines that the non-azeotropic mixed refrigerant is not leaking.

Although the mixed refrigerant having the composition ratio at the time of filling flows into the refrigerant circuit 10, there is a difference in the composition ratio such as evaporation from the low boiling point refrigerant at the time of phase change. Therefore, in the procedure shown in FIG. 6, when the determining unit 54 determines that there is a refrigerant leak, the location where the refrigerant leak occurs can be identified as the location where the phase change has occurred.

The inspection mode executing means 52 may control the non-azeotropic mixed refrigerant to circulate in the refrigerant circuit 10 even when the air temperature in the cooling chamber reaches the set temperature during the execution of the inspection mode. In this case, the control device 50 can prevent the thermostat from being turned off and can determine the refrigerant leakage.

The refrigerating air-conditioning apparatus 100 of Embodiment 1 uses the non-azeotropic mixed refrigerant as the enclosed refrigerant, and in the inspection mode, the theoretical saturation temperature of the refrigerant pressure flowing into the evaporator 14 and the measured temperature of the evaporator 14 The presence/absence of refrigerant leakage is determined by comparing the temperature difference TD of 1 to the threshold value.

According to the first embodiment, by utilizing the fact that the saturation temperature of the refrigerant at a specific set pressure changes in accordance with the change in the composition ratio of the refrigerant, the refrigerant flows in a gas-liquid two-phase state Detect the occurrence of refrigerant leakage. When a refrigerant leak is detected, the location of the refrigerant leak can be specified in the section from the expansion section 13 to the outlet of the evaporator 14 or in the condenser 12. Therefore, the operator is less burdened with the work for identifying the refrigerant leakage site. Moreover, since the time required to identify the refrigerant leakage portion can be significantly reduced, the amount of refrigerant leakage during work can be reduced. Since the amount of refrigerant leakage is reduced, the influence of the refrigerant on the global environment is suppressed.

10 Refrigerant circuit, 11 Compressor, 12 Condenser, 13 Expansion part, 14 Evaporator, 15 Accumulator, 16 Liquid receiver, 21 Condensation temperature sensor, 22 Expansion part inlet temperature sensor, 23 Inflow pressure sensor, 24 Inflow temperature sensor, 50 control device, 51 refrigeration cycle control means, 52 inspection mode execution means, 53 calculation means, 54 determination means, 100 refrigeration/air-conditioning device.

Claims (8)

A compressor, a condenser, an expansion part, an evaporator and an accumulator are connected by a pipe, and a refrigerant circuit in which a non-azeotropic mixed refrigerant in which a plurality of kinds of refrigerants having different boiling points are mixed is circulated,
An inflow temperature sensor for measuring the temperature of the non-azeotropic mixed refrigerant flowing into the evaporator;
In the inspection mode in which the refrigerant circuit is controlled so that the pressure of the non-azeotropic mixed refrigerant flowing into the evaporator becomes a set pressure, the temperature of the saturation temperature at the set pressure and the temperature measured by the inflow temperature sensor. A controller for determining the presence or absence of leakage of the non-azeotropic mixed refrigerant by calculating a difference, comparing the temperature difference and a threshold value set based on different boiling points of the plurality of types of refrigerants ,
Refrigerating and air-conditioning system. Further comprising an inflow pressure sensor for measuring the pressure of the non-azeotropic mixed refrigerant flowing into the evaporator,
The control device is
When the set temperature of the air-conditioned space is stored and the evaporation temperature converted from the pressure of the non-azeotropic mixed refrigerant flowing through the evaporator is higher than the set temperature, the inspection mode is executed. The refrigeration air-conditioning apparatus according to Item 1. The control device is
The refrigeration according to claim 1 or 2, wherein, in the inspection mode, the refrigerant circuit is controlled so that the condensation temperature of the non-azeotropic mixed refrigerant is lower than that in a normal operation mode in which the air-conditioned space is air-conditioned. Air conditioner. The control device is
In the inspection mode, the condensing temperature of the non-azeotropic mixed refrigerant flowing through the condenser, and the degree of supercooling of the non-azeotropic mixed refrigerant flowing to the inlet side of the expansion section, each target value and the allowable range. The refrigerating and air-conditioning apparatus according to any one of claims 1 to 3, wherein the refrigerant circuit is controlled so as to coincide with each other. The control device is
In the inspection mode, the pressure of the non-azeotropic mixed refrigerant flowing in the condenser, and the degree of supercooling of the non-azeotropic mixed refrigerant flowing to the inlet side of the expansion section, in the respective target value and allowable range. The refrigerating and air-conditioning apparatus according to any one of claims 1 to 3, wherein the refrigerant circuits are controlled so as to coincide with each other. The control device is
The refrigerating and air-conditioning apparatus according to claim 1, wherein the inspection mode is executed after the defrosting operation is completed. The control device is
The refrigerating air conditioner according to any one of claims 1 to 6, wherein in the inspection mode, the non-azeotropic mixed refrigerant is circulated in the refrigerant circuit even when the air temperature of the air conditioning target space reaches a set temperature. .. A compressor, a condenser, an expansion part, an evaporator and an accumulator are connected by a pipe, and a refrigerant circuit in which a non-azeotropic mixed refrigerant in which a plurality of kinds of refrigerants having different boiling points are mixed is circulated, and the non-refrigerant flowing into the evaporator. A control device for controlling a refrigerating and air-conditioning apparatus having an inflow temperature sensor for measuring the temperature of an azeotropic mixed refrigerant,
An inspection mode executing means for controlling the refrigerant circuit so that the pressure of the non-azeotropic mixed refrigerant flowing into the evaporator becomes a set pressure,
Calculating means for calculating a temperature difference between the saturation temperature at the set pressure and the temperature measured by the inflow temperature sensor;
Judgment means for judging the presence or absence of leakage of the non-azeotropic mixed refrigerant by comparing the temperature difference and a threshold value set based on different boiling points of the plurality of kinds of refrigerants ,
Control device having a.

Images