JPWO2017179210A1 - Refrigeration equipment - Google Patents

Abstract

Judgment of refrigerant shortage is made with a small refrigerant shortage amount and leakage amount, and the time required for refrigerant shortage judgment is shortened. The refrigeration apparatus (1) includes a compressor (21), a heat source side heat exchanger (23), a heat source side fan (27) for blowing air to the heat source side heat exchanger, and a supercooler (22). The heat source side unit (2), the usage side expansion valve (41), and at least one usage side unit (4) having a usage side heat exchanger are connected by piping (6, 7) to circulate the refrigerant. And a refrigerant shortage determining unit (3) for determining the shortage of the refrigerant amount filled in the refrigerant circuit. The refrigerant shortage determining unit determines whether the refrigerant amount is excessive or insufficient by comparing the temperature efficiency ε of the subcooler with the temperature efficiency threshold value εline. The refrigerant shortage determination unit changes the temperature efficiency threshold according to the operating state of the refrigeration apparatus.

Description

  The present invention relates to a refrigeration apparatus that determines the amount of refrigerant in a refrigerant circuit.

  In an air conditioner such as a refrigeration apparatus, if the amount of refrigerant is excessive or insufficient, the capacity of the refrigeration apparatus may be reduced or components may be damaged. Therefore, in order to prevent the occurrence of such a problem, some have a function of determining whether the amount of refrigerant filled in the refrigeration apparatus is excessive or insufficient.

  As a method for determining the refrigerant shortage in the conventional refrigeration apparatus, for example, the average temperature efficiency εA of the temperature efficiency ε of the supercooling heat exchanger is used. In this case, an example has been proposed in which the determination threshold value εline of the temperature efficiency ε is determined to be a constant value of 0.4 (see Patent Document 1). Here, the temperature efficiency is generally expressed by the following (Formula 1).

  In Patent Document 1, in the case of an air supercooling heat exchanger in which the high temperature side is a refrigerant and the low temperature side is an air fluid, the temperature efficiency is such that the supercooling degree of the refrigerant at the outlet of the supercooling heat exchanger is supercooled. The value is divided by the maximum temperature difference of the heat exchanger. In Patent Document 1, the degree of supercooling of the refrigerant at the outlet of the supercooling heat exchanger is a value obtained by subtracting the subcooling heat exchanger outlet temperature from the condenser outlet temperature, and the maximum temperature of the supercooling heat exchanger. It is described that the difference is a value obtained by subtracting the outside air temperature from the condenser outlet temperature. The condenser outlet temperature is TH5, the supercooling heat exchanger outlet temperature is TH8, the outside air temperature is TH6, and the temperature efficiency ε of the supercooling heat exchanger is expressed by the following (Formula 2).

  When refrigerant leakage occurs, the extent to which refrigerant shortage can be determined is roughly determined by the "temperature efficiency value when the refrigerant amount is properly sealed" and "temperature efficiency ε determination threshold. It changes depending on the difference of “εline”. That is, if the difference between “the value of temperature efficiency when the amount of refrigerant is properly sealed” and “the determination threshold value εline of temperature efficiency ε” is large, it is not possible to determine the lack of refrigerant unless a large amount of refrigerant leaks. Conversely, when the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is small, the refrigerant shortage can be determined with a small refrigerant leakage amount. it can.

JP 2012-132039 A

However, in the refrigeration apparatus described in Patent Document 1, since the temperature efficiency value when the refrigerant amount is properly sealed varies depending on the operating frequency, the evaporation temperature, and the fan airflow value, “the refrigerant amount is properly sealed. The difference between the “temperature efficiency value” and the “temperature efficiency ε determination threshold value εline” varies depending on the operating conditions. Therefore, depending on the operating conditions, it may not be possible to determine the shortage of refrigerant unless a large amount of refrigerant leaks. For example, as shown in FIG. 14, under the conditions of a fan air volume of 40 m ³ / min and an operating frequency of 100 Hz, the “temperature efficiency value when the refrigerant amount is properly sealed” is 0.45, and the “temperature efficiency ε determination threshold value”. Since the value εline ”(“ threshold value ”indicated by a broken line in the graph of FIG. 14) is 0.40, the difference is as small as 0.05, and the refrigerant shortage can be detected with a small amount of refrigerant leakage. On the other hand, under the conditions of a fan air volume of 100 m ³ / min and an operating frequency of 30 Hz, “temperature efficiency value when refrigerant amount is properly sealed” is 0.80, and “temperature efficiency ε determination threshold εline” is 0. Therefore, the difference is as large as 0.40, and the refrigerant shortage cannot be detected unless a large amount of refrigerant leaks.

  In the determination using the temperature efficiency, the change due to the operating condition of the refrigeration apparatus is smaller than the determination of the lack of the refrigerant amount using the change in the degree of supercooling, but the difference in the temperature efficiency due to the above operating condition occurs. . In particular, the temperature range in the cabinet of a showcase, unit cooler, etc. is about −50 to + 23 ° C., and the temperature range in the cabinet is larger than the temperature range of the air conditioner +15 to + 30 ° C., so the operating conditions vary greatly. . Not having the condition fixing mode like the refrigerant shortage determination mode is also a reason why the conditions at the time of refrigerant shortage determination change greatly. Thus, depending on the operating conditions, there may be a case where a shortage of refrigerant cannot be detected unless a large amount of refrigerant leaks. If a large amount of refrigerant leakage is required to determine whether or not refrigerant leakage has occurred, there is a concern about the influence of the refrigerant leakage on the global environment such as global warming. Further, if the amount of refrigerant leakage is large, the additional amount of leakage increases, and there is a concern about an increase in recovery cost.

  The present invention has been made against the background of the above-described problems, and it is an object of the present invention to determine whether or not refrigerant is insufficient by determining the shortage of refrigerant and the amount of leakage, and to shorten the time required for determining whether or not refrigerant is insufficient. .

  A refrigeration apparatus according to the present invention includes a compressor, a heat source side heat exchanger, a heat source side fan that blows air to the heat source side heat exchanger, a heat source side unit having a supercooler, a use side expansion valve, And a refrigeration apparatus having a refrigerant circuit that circulates a refrigerant, and is connected to at least one usage side unit having a usage side heat exchanger, and the degree of supercooling of the refrigerant on the outlet side of the subcooler, Refrigerant for determining the shortage of the amount of refrigerant charged in the refrigerant circuit using the temperature efficiency of the subcooler, which is a value divided by the maximum temperature difference between the high temperature side fluid and the low temperature side fluid exchanged by the subcooler. A shortage determination unit is provided, and the refrigerant shortage determination unit compares the temperature efficiency of the subcooler with the temperature efficiency threshold value that is changed according to the operating state of the refrigeration apparatus, and determines the shortage of the refrigerant amount.

  According to the refrigeration apparatus according to the present invention, the temperature efficiency threshold value is changed according to the operating state, and this temperature efficiency threshold value is used for comparison with the temperature efficiency of the subcooler to determine the shortage of the refrigerant amount. ing. Therefore, it is possible to determine the shortage of the refrigerant amount according to the operating state of the refrigeration apparatus, and it is possible to determine the shortage of the refrigerant amount with a small refrigerant leakage amount.

It is the figure which described typically an example of the refrigerant circuit of the freezing apparatus which concerns on embodiment of this invention. It is a control block diagram of the refrigeration apparatus concerning an embodiment of the invention. FIG. 2 is an example of a ph diagram when the refrigerant amount is appropriate in the refrigeration apparatus illustrated in FIG. 1. FIG. 2 is an example of a ph diagram when the refrigerant amount is insufficient in the refrigeration apparatus illustrated in FIG. 1. It is a figure explaining the relationship between the refrigerant | coolant amount of the freezing apparatus described in FIG. 1, the supercooling degree of a 1st supercooler, and the operating conditions of a freezing apparatus. In the refrigeration apparatus shown in FIG. 1, when the amount of refrigerant is an appropriate amount, a diagram illustrating an example of a temperature change of the refrigerant when the refrigerant flows in the order of the heat source side heat exchanger, the receiver, and the air supercooler. is there. It is a figure explaining the relationship between the refrigerant | coolant amount of the freezing apparatus of FIG. 1, the temperature efficiency of a 1st subcooler, and the operating conditions of a freezing apparatus. It is a figure explaining an example of the relationship between the temperature efficiency value of the refrigeration apparatus which concerns on embodiment of this invention, a fan output, and an operating frequency. It is a figure explaining an example of the relationship between the temperature efficiency value of the freezing apparatus which concerns on embodiment of this invention, the high temperature side refrigerant | coolant circulation amount, and a fan air volume. It is a figure explaining an example of the relationship between the temperature efficiency value of the refrigeration apparatus which concerns on embodiment of this invention, a high pressure, and an operating frequency. It is a flowchart which shows the procedure of the refrigerant | coolant shortage determination operation | movement in this Embodiment. It is a conceptual diagram explaining the stability determination conditions in embodiment of this invention. It is the figure which described typically the refrigerant circuit of the freezing apparatus which concerns on the modification of this invention. It is a figure explaining an example of the relationship between the temperature efficiency value by a prior art, a fan air volume, and an operating frequency. It is a figure explaining an example of the relationship between the temperature efficiency value of the freezing apparatus which concerns on embodiment of this invention, and (DELTA) T.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is omitted or simplified as appropriate. Moreover, the shape, size, arrangement, and the like of the configurations described in the drawings can be appropriately changed within the scope of the present invention.

Embodiment.
[Refrigeration equipment]
FIG. 1 is a diagram schematically illustrating an example of a refrigerant circuit of a refrigeration apparatus according to an embodiment of the present invention. The refrigeration apparatus 1 illustrated in FIG. 1 performs, for example, room cooling such as a room, a warehouse, a showcase, or a refrigerator by performing a vapor compression refrigeration cycle operation. The refrigeration apparatus 1 includes, for example, one heat source side unit 2 and two usage side units 4 connected in parallel to the heat source side unit 2. The heat source side unit 2 and the use side unit 4 are connected by the liquid refrigerant extension pipe 6 and the gas refrigerant extension pipe 7, whereby the refrigerant circuit 10 for circulating the refrigerant is formed. The refrigerant charged in the refrigerant circuit 10 of this embodiment is, for example, R410A, which is an HFC mixed refrigerant. In the example of FIG. 1, one heat source side unit 2 and two usage side units 4 are described. However, two or more heat source side units 2 may be used. May be one or three or more. When there are a plurality of heat source side units 2, the capacities of the plurality of heat source side units 2 may be the same or different. When there are a plurality of usage-side units 4, the capacity of the plurality of usage-side units 4 may be the same or different. In the following description, the refrigeration apparatus 1 in which the refrigerant exchanges heat with air will be described. However, the refrigerant may be a refrigeration apparatus that exchanges heat with a fluid such as water, refrigerant, or brine.

[Usage unit]
The use side unit 4 is an indoor unit that is installed indoors, for example, and includes a use side refrigerant circuit 10 a and a use side control unit 32 that constitute a part of the refrigerant circuit 10. The use side refrigerant circuit 10 a includes a use side expansion valve 41 and a use side heat exchanger 42. The use side expansion valve 41 adjusts the flow rate of the refrigerant flowing through the use side refrigerant circuit 10a, and is configured by, for example, an electronic expansion valve or a temperature type expansion valve. The use side expansion valve 41 may be disposed in the heat source side unit 2, and in this case, the use side expansion valve 41 is, for example, the first subcooler 22 and the liquid side of the heat source side unit 2. It is arranged between the closing valve 28. The use-side heat exchanger 42 is, for example, a fin and tube heat exchanger configured to include a heat transfer tube and a large number of fins, and functions as an evaporator that evaporates the refrigerant.

  In the vicinity of the use side heat exchanger 42, a use side fan 43 that blows air to the use side heat exchanger 42 is disposed. The use-side fan 43 includes, for example, a centrifugal fan or a multi-blade fan, and is driven by a motor not shown. The use side fan 43 can adjust the amount of air blown to the use side heat exchanger 42.

[Heat source side unit]
The heat source side unit 2 includes, for example, a heat source side refrigerant circuit 10b, a first injection circuit 71, and a heat source side control unit 31 that constitute a part of the refrigerant circuit 10.

  The heat source side refrigerant circuit 10 b includes a compressor 21, a heat source side heat exchanger 23, a receiver 25, a first subcooler 22, a liquid side closing valve 28, a gas side closing valve 29, and an accumulator 24. The first injection circuit 71 branches a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side heat exchanger 42 from the heat source side refrigerant circuit 10b and returns it to the intermediate pressure part of the compressor 21. The injection amount adjusting valve 72 is included.

  The compressor 21 is, for example, an inverter compressor that is controlled by an inverter, and can change the capacity (the amount of refrigerant sent out per unit time) by arbitrarily changing the operating frequency. The compressor 21 may be a constant speed compressor that operates at 50 Hz or 60 Hz. FIG. 1 shows an example having one compressor 21, but two or more compressors 21 are connected in parallel according to the load size of the usage-side unit 4. May be.

  The heat source side heat exchanger 23 is, for example, a fin and tube heat exchanger configured to include a heat transfer tube and a large number of fins, and functions as a condenser that condenses the refrigerant. In the vicinity of the heat source side heat exchanger 23, a heat source side fan 27 for blowing air to the heat source side heat exchanger 23 is disposed. The heat source side fan 27 blows outside air sucked from the outside of the heat source side unit 2 to the heat source side heat exchanger 23. The heat source side fan 27 includes, for example, a centrifugal fan or a multiblade fan, and is driven by a motor not shown. The heat source side fan 27 can adjust the amount of air blown to the heat source side heat exchanger 23.

  The receiver 25 is disposed between the heat source side heat exchanger 23 and the first subcooler 22 and stores excess liquid refrigerant. For example, the receiver 25 is a container for storing excess liquid refrigerant. The surplus liquid refrigerant is generated in the refrigerant circuit 10 in accordance with, for example, the load size of the usage-side unit 4, the refrigerant condensing temperature, the outside air temperature, the evaporation temperature, or the capacity of the compressor 21. .

  The first subcooler 22 exchanges heat between the refrigerant and the air, and is formed integrally with the heat source side heat exchanger 23. That is, in the example of this embodiment, a part of the heat exchanger is configured as the heat source side heat exchanger 23, and the other part of the heat exchanger is configured as the first subcooler 22. The first subcooler 22 corresponds to the “supercooler” of the present invention. In addition, the 1st subcooler 22 and the heat source side heat exchanger 23 may be comprised separately. In that case, a fan (not shown) that blows air to the first subcooler 22 is disposed in the vicinity of the first subcooler 22.

  The liquid side closing valve 28 and the gas side closing valve 29 are constituted by valves that perform opening and closing operations such as a ball valve, an on-off valve, or an operation valve, for example.

  In the example shown in FIG. 1, the inlet of the first injection circuit 71 is connected between the first subcooler 22 and the liquid side closing valve 28, but the inlet of the first injection circuit 71 is It may be connected between the receiver 25 and the first subcooler 22, may be connected to the receiver 25, or may be connected between the heat source side heat exchanger 23 and the receiver 25. .

[Control unit and sensors]
Next, the control unit and sensors included in the refrigeration apparatus 1 of this embodiment will be described. The heat source side unit 2 includes a heat source side control unit 31 that controls the entire refrigeration apparatus 1. The heat source side control unit 31 includes a microcomputer and a memory. Further, the usage side unit 4 includes a usage side control unit 32 that controls the usage side unit 4. The use side control unit 32 includes a microcomputer and a memory. The use side control unit 32 and the heat source side control unit 31 can communicate and exchange control signals. For example, the use side control unit 32 receives an instruction from the heat source side control unit 31. In response, the user side unit 4 is controlled.

  The refrigeration apparatus 1 according to this embodiment includes an intake temperature sensor 33a, a discharge temperature sensor 33b, a suction outside air temperature sensor 33c, a supercooler high pressure side outlet temperature sensor 33d, a use side heat exchange inlet temperature sensor 33e, and a use side heat exchange. It includes an outlet temperature sensor 33f, a suction air temperature sensor 33g, a suction pressure sensor 34a, and a discharge pressure sensor 34b. The suction temperature sensor 33a, the discharge temperature sensor 33b, the suction outside air temperature sensor 33c, the supercooler high pressure side outlet temperature sensor 33d, the suction pressure sensor 34a, and the discharge pressure sensor 34b are disposed in the heat source side unit 2 and are controlled by the heat source. Connected to the unit 31. The use side heat exchange inlet temperature sensor 33e, the use side heat exchange outlet temperature sensor 33f, and the intake air temperature sensor 33g are provided in the use side unit 4 and connected to the use side control unit 32.

  The suction temperature sensor 33a detects the temperature of the refrigerant sucked by the compressor 21. The discharge temperature sensor 33b detects the temperature of the refrigerant discharged from the compressor 21. The subcooler high pressure side outlet temperature sensor 33d detects the temperature of the refrigerant that has passed through the first subcooler 22. The use side heat inlet temperature sensor 33e detects the evaporation temperature of the gas-liquid two-phase refrigerant flowing into the use side heat exchanger. The use-side heat exchange outlet temperature sensor 33f detects the temperature of the refrigerant that has flowed out of the use-side heat exchanger 42. The above-mentioned sensor for detecting the temperature of the refrigerant is disposed, for example, in contact with the refrigerant pipe or inserted into the refrigerant pipe, and detects the temperature of the refrigerant.

  The suction outside air temperature sensor 33c detects the ambient temperature outside the room by detecting the temperature of the air before passing through the heat source side heat exchanger 23. The intake air temperature sensor 33g detects the ambient temperature in the room where the use side heat exchanger 42 is installed by detecting the temperature of the air before passing through the use side heat exchanger 42.

  The suction pressure sensor 34 a is disposed on the suction side of the compressor 21 and detects the pressure of the refrigerant sucked into the compressor 21. The suction pressure sensor 34 a may be disposed between the gas side closing valve 29 and the compressor 21. The discharge pressure sensor 34b is disposed on the discharge side of the compressor 21 and detects the pressure of the refrigerant discharged from the compressor 21.

  In the example of the present embodiment, the condensation temperature of the heat source side heat exchanger 23 is obtained by converting the pressure of the discharge pressure sensor 34b into the saturation temperature, but the condensation temperature of the heat source side heat exchanger 23 is obtained. Can also be obtained by arranging a temperature sensor in the heat source side heat exchanger 23.

  FIG. 2 is a control block diagram of the refrigeration apparatus according to the embodiment of the present invention. The control unit 3 controls the entire refrigeration apparatus 1, and the control unit 3 of the present embodiment is included in the heat source side control unit 31. The control unit 3 corresponds to the “refrigerant lack determination unit” of the present invention. The control unit 3 includes an acquisition unit 3a, a calculation unit 3b, a storage unit 3c, and a drive unit 3d. The acquisition unit 3a, the calculation unit 3b, and the drive unit 3d are configured to include, for example, a microcomputer, and the storage unit 3c is configured to include, for example, a semiconductor memory. The acquisition unit 3a acquires information such as temperature and pressure detected by sensors such as a pressure sensor and a temperature sensor. The calculation unit 3b performs processing such as calculation, comparison, and determination using the information acquired by the acquisition unit 3a. The drive unit 3d performs drive control of the compressor 21, valves, fans, and the like using the results calculated by the calculation unit 3b. The storage unit 3c stores physical property values (saturation pressure, saturation temperature, etc.) of the refrigerant, data for the calculation unit 3b to perform calculations, and the like. The calculation unit 3b can refer to or update the storage content of the storage unit 3c as necessary.

  The control unit 3 includes an input unit 3e and an output unit 3f. The input unit 3e inputs operation input from a remote controller or switches (not shown) or communication data from communication means (not shown) such as a telephone line or a LAN line. The output unit 3f outputs the processing result of the control unit 3 to a display unit (not shown) such as an LED or a monitor, and outputs it to a notification unit (not shown) such as a speaker, or a telephone line or a LAN line. To a communication means (not shown). In addition, when outputting information to a remote place by a communication means, it is good to provide the communication means (not shown) which has the same communication protocol in both the refrigeration apparatus 1 and a remote device (not shown).

  For example, it is possible to determine whether the refrigerant amount is insufficient or the like using the refrigeration apparatus 1 and a remote apparatus (not shown). In that case, for example, the calculation unit 3b calculates the temperature efficiency ε of the first subcooler 22 using the information acquired by the acquisition unit 3a, and the output unit 3f calculates the temperature efficiency calculated by the calculation unit 3b. Send ε to the remote device. The remote device is provided with a refrigerant shortage determining means (not shown) for determining the shortage of the refrigerant amount, and determines the shortage of the refrigerant amount using the temperature efficiency ε. By managing the refrigerant shortage information and the like by the remote device, it is possible to detect an abnormality or the like of the refrigeration device 1 at a place where the remote device is installed at an early stage. The maintenance of the refrigeration apparatus 1 can be performed at an early stage.

  In the above description, the example in which the control unit 3 is included in the heat source side control unit 31 has been described. However, the control unit 3 may be included in the use side control unit 32 or the heat source The side control unit 31 and the use side control unit 32 may be configured separately.

[Operation of refrigeration equipment (when the amount of refrigerant is appropriate)]
FIG. 3 is an example of a ph diagram when the refrigerant amount is appropriate in the refrigeration apparatus illustrated in FIG. 1. First, the operation of the refrigeration apparatus 1 when the refrigerant amount is appropriate will be described. From the point K to the point L in FIG. 3, the compressor 21 illustrated in FIG. 1 compresses the refrigerant. From the point L to the point M in FIG. 3, the high-temperature and high-pressure gas refrigerant compressed by the compressor 21 in FIG. 1 is heat-exchanged by the heat source side heat exchanger 23 functioning as a condenser to be condensed and liquefied. Note that the refrigerant that has been heat-exchanged by the heat source side heat exchanger 23 and condensed and liquefied flows into the receiver 25 and is temporarily stored in the receiver 25. The amount of the refrigerant stored in the receiver 25 varies depending on the operation load, the outside air temperature, the condensation temperature, and the like of the usage-side unit 4.

  From the point M to the point N in FIG. 3, the liquid refrigerant stored in the receiver 25 in FIG. 1 is supercooled by the first subcooler 22. The degree of supercooling at the outlet of the first supercooler 22 is calculated by subtracting the temperature of the supercooler high-pressure side outlet temperature sensor 33d from the condensation temperature.

  The liquid refrigerant supercooled by the first subcooler 22 in FIG. 1 from the point N to the point O in FIG. 3 passes through the liquid side closing valve 28 and the liquid refrigerant extension pipe 6 to the usage side unit 4. It is sent and decompressed by the use side expansion valve 41 to become a low-pressure gas-liquid two-phase refrigerant.

  The gas-liquid two-phase refrigerant decompressed by the use side expansion valve 41 in FIG. 1 from the point O to the point K in FIG. 3 is gasified in the use side heat exchanger 42 functioning as an evaporator. The degree of superheat of the refrigerant is calculated by subtracting the evaporation temperature of the refrigerant detected by the use side heat exchange inlet temperature sensor 33e from the temperature detected by the use side heat exchange outlet temperature sensor 33f. The gas refrigerant gasified by the use side heat exchanger 42 returns to the compressor 21 via the gas refrigerant extension pipe 7, the gas side closing valve 29, and the accumulator 24.

  Next, the injection circuit will be described. The first injection circuit 71 is for lowering the refrigerant temperature of the discharge part of the compressor 21. The inlet of the first injection circuit 71 is connected between the outlet of the first subcooler 22 and the liquid side shut-off valve 28, and a part of the high-pressure liquid refrigerant subcooled by the first subcooler 22 is Then, the pressure is reduced by the injection amount adjusting valve 72 to become a two-phase refrigerant having an intermediate pressure, and flows into the injection portion of the compressor 21.

[Operation of refrigeration equipment (when refrigerant amount is insufficient)]
FIG. 4 is an example of a ph diagram when the refrigerant amount is insufficient in the refrigeration apparatus illustrated in FIG. 1. For example, when the refrigerant leaks from the refrigeration apparatus 1 illustrated in FIG. 1 and the amount of the refrigerant decreases, the excess liquid refrigerant stored in the receiver 25 decreases while the excess liquid refrigerant is stored in the receiver 25. To do. While the surplus liquid refrigerant is present in the receiver 25, the refrigeration apparatus 1 operates in the same manner as when the refrigerant amount is appropriate, as shown in FIG.

  When the refrigerant further decreases and the excess liquid refrigerant in the receiver 25 disappears, the enthalpy at the outlet of the heat source side heat exchanger 23 functioning as a condenser increases as shown by a point M1 in FIG. The refrigerant state at the outlet of the heat exchanger 23 becomes a two-phase state. Further, as the enthalpy at the outlet of the heat source side heat exchanger 23 increases, the first subcooler 22 performs the condensing and supercooling of the two-phase refrigerant, so that the point N1 indicates The enthalpy at the outlet of the first subcooler 22 is also increased.

[Comparative example]
Here, the comparative example compared with this Embodiment is demonstrated. In the comparative example, the refrigerant amount is determined using the degree of supercooling of the refrigerant. For example, when the amount of refrigerant is insufficient due to leakage of the refrigerant, the degree of supercooling decreases as shown in FIG. Therefore, in the comparative example, it is determined that the refrigerant amount is insufficient when the degree of supercooling becomes smaller than a preset threshold value.

  FIG. 5 is a diagram illustrating the relationship among the refrigerant amount of the refrigeration apparatus illustrated in FIG. 1, the degree of supercooling of the first supercooler, and the operating conditions of the refrigeration apparatus. As shown in FIG. 5, the degree of supercooling of the first subcooler 22 varies greatly depending on the operating conditions of the refrigeration apparatus 1 (outside air temperature, heat exchange amount, refrigerant circulation amount, evaporation temperature, etc.). For this reason, as in the comparative example, when determining the shortage of the refrigerant amount using the supercooling degree, it is necessary to set the supercooling degree threshold value S low so as not to make an erroneous determination. As described above, in the comparative example, since the supercooling degree threshold value S must be set low, it takes a long time to determine whether the refrigerant amount is insufficient. For example, when the refrigerant is leaking, The amount of leakage will increase.

[Judgment of refrigerant amount]
Therefore, in the present embodiment, the refrigerant amount is determined using the temperature efficiency ε of the first subcooler 22 that has a smaller variation with respect to changes in the operating conditions of the refrigeration apparatus 1 than the degree of supercooling. Hereinafter, determination of the refrigerant amount using temperature efficiency will be described.

  FIG. 6 is an example of the temperature change of the refrigerant when the refrigerant flows in the order of the heat source side heat exchanger, the receiver, and the air supercooler in the refrigeration apparatus shown in FIG. It is a figure explaining. In FIG. 6, the vertical axis indicates the temperature, and the temperature is higher at the top. The horizontal axis indicates the refrigerant path of the heat source side heat exchanger 23, the receiver 25, and the first subcooler 22. s1 is the refrigerant condensation temperature, s2 is the refrigerant temperature at the outlet of the first subcooler 22, and s3 is the outside air temperature.

  The temperature efficiency ε of the first subcooler 22 indicates the efficiency of the first subcooler 22, and the maximum temperature difference A is taken as the denominator and the actual temperature difference B is taken as the numerator. . In the first subcooler 22, the maximum possible temperature difference A is the difference between the refrigerant condensing temperature s1 and the outside air temperature s3, and the actually possible temperature difference B is the refrigerant condensing temperature s1 and the first subcooling. This is the difference from the temperature s2 at the outlet of the vessel 22. The temperature efficiency ε is expressed by the following (Formula 3).

  FIG. 7 is a diagram illustrating the relationship among the refrigerant amount of the refrigeration apparatus illustrated in FIG. 1, the temperature efficiency of the first subcooler, and the operating conditions of the refrigeration apparatus. In FIG. 7, the horizontal axis represents the refrigerant amount of the refrigerant, and the vertical axis represents the temperature efficiency ε of the first subcooler 22. As shown in FIG. 7, when the refrigerant amount decreases, the refrigerant amount becomes E, and the surplus liquid refrigerant in the receiver 25 disappears, the temperature efficiency ε of the first subcooler 22 decreases. Therefore, when the temperature efficiency ε becomes smaller than the preset temperature efficiency threshold value T1, it is determined that the refrigerant has leaked. The temperature efficiency ε indicates the performance of the first subcooler 22, and since the fluctuation due to the operating condition of the refrigeration apparatus 1 is smaller than the degree of supercooling, the threshold value of the refrigeration apparatus 1 can be easily set. .

  Generally, the temperature efficiency of a heat exchanger is expressed by the following (Formula 4).

The first subcooler 22 of the present embodiment exchanges heat between the refrigerant and the air, and the high temperature side fluid is refrigerant and the low temperature side fluid is air. Therefore, K: heat passage rate (W / (m ² · K)) varies depending on the air flow rate and the refrigerant circulation rate. The temperature efficiency decreases as the air flow rate decreases or the refrigerant circulation rate increases.

ρh · Vh: High-temperature side fluid density (kg / m ³ ) × High-temperature side fluid volume flow rate (m ³ / h) is refrigerant circulation amount G (kg / h). descend. The refrigerant circulation amount varies depending on the compressor frequency, the refrigerant compressor intake gas pressure, and the compressor intake gas temperature. Ch: The high temperature side fluid specific heat (KJ / kg) fluctuates depending on the high pressure of the refrigerant, and the temperature efficiency decreases as the high pressure increases. Vm: The low-temperature side fluid volume flow rate (m ³ / h) is the air volume on the air side, and varies depending on the air volume of the heat source side fan 27.

A: The heat transfer area (m ² ) is a constant value unique to the refrigeration apparatus 1. ρm: Low-temperature side fluid density (kg / m ³ ), Cm: Low-temperature side fluid specific heat (KJ / kg) is the density of air and specific heat, but has a substantially constant value.

  From the above, the heat transfer area (A), the low temperature side fluid density (ρm), and the low temperature side fluid specific heat (Cm) of the refrigeration apparatus 1 are constant values. Further, the temperature efficiency varies depending on the refrigerant circulation amount that varies the heat passage rate (K), the high pressure that varies the high-temperature side fluid specific heat (Ch), and the air flow rate that varies depending on the air volume of the heat source side fan 27. The refrigerant circulation amount varies depending on the compressor frequency, the refrigerant compressor intake gas pressure, and the compressor intake gas temperature. Therefore, when the temperature efficiency threshold value is changed according to the operating conditions, the refrigerant circulation amount, that is, the compressor frequency, the compressor intake gas pressure of the refrigerant, the compressor intake gas temperature, the air flow rate, and the high pressure pressure are set. And set.

[Change threshold value according to operating conditions]
The extent to which refrigerant shortage can be determined when refrigerant leakage occurs is roughly determined by “temperature efficiency value when refrigerant amount is properly sealed” and “temperature efficiency ε determination threshold εline. ”Varies depending on the difference. That is, when the difference between “the value of temperature efficiency when the amount of refrigerant is properly sealed” and “the determination threshold value εline of temperature efficiency ε” is large, it is not possible to determine the shortage of refrigerant unless a large amount of refrigerant leaks. Conversely, when the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold value εline” is small, it is possible to determine the shortage of refrigerant with a small refrigerant leakage amount. .

  Note that the temperature efficiency, which is an index for determining the refrigerant shortage, varies less depending on the operating conditions than the supercooling value or the like, but varies depending on the operating conditions as described above. Therefore, changing the threshold value according to the operating conditions can reduce the difference between the "temperature efficiency value when the refrigerant amount is properly sealed" and the "temperature efficiency ε judgment threshold value εline", and the amount of refrigerant It is possible to determine the refrigerant shortage by the leakage amount. A threshold setting method according to operating conditions will be described below.

[Threshold setting method according to operating conditions 1]
As described above, the temperature efficiency varies depending on the air flow rate. Therefore, in this embodiment, the threshold value is changed by the fan output% as “threshold setting method 1”. FIG. 8 is a diagram illustrating an example of the relationship between the temperature efficiency value of the refrigeration apparatus according to the embodiment of the present invention, the fan output, and the operating frequency. Specifically, as shown in FIG. 8, the temperature efficiency threshold is set to be smaller as the fan output decreases. As a result, under the condition of a fan air volume of 40%, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is about 0.05 to 0.10. Become.

FIG. 14 is a diagram for explaining an example of the relationship between the temperature efficiency value, the fan air volume, and the operating frequency according to the prior art. For example, as shown in FIG. 14, under the conditions of a fan air volume of 40 m ³ / min and an operating frequency of 100 Hz, “the value of temperature efficiency when the refrigerant amount is properly sealed” is 0.45, and the “threshold value shown by a broken line” "The determination threshold value εline of the temperature efficiency ε" is 0.40, so the difference is as small as 0.05, and the refrigerant shortage can be detected with a small amount of refrigerant leakage. On the other hand, under the conditions of a fan air volume of 100 m ³ / min and an operating frequency of 30 Hz, “temperature efficiency value when refrigerant amount is properly sealed” is 0.80, and “temperature efficiency ε determination threshold εline” is 0. Therefore, the difference is as large as 0.40, and the refrigerant shortage cannot be detected unless a large amount of refrigerant leaks.

  According to the threshold setting method 1, the difference is improved as compared with the case where “the determination threshold εline of the temperature efficiency ε” is a constant value as shown in FIG. However, the difference between “the temperature efficiency value when the refrigerant amount is properly sealed” and “the determination threshold value εline of the temperature efficiency ε” is about 0.20 to 0.30 under the condition that the fan air volume is 100%. The difference is improved as compared with the case where “the determination threshold value εline of the temperature efficiency ε” in FIG. 14 is a constant value, but the difference is larger than the condition of the fan air volume 40%.

[Threshold setting method 2 according to operating conditions]
As described above, the temperature efficiency varies depending on the refrigerant circulation amount. Therefore, in the present embodiment, the threshold value is changed according to the refrigerant circulation amount as “threshold value setting method 2”. FIG. 9 is a diagram for explaining an example of the relationship between the temperature efficiency value of the refrigeration apparatus according to the embodiment of the present invention, the high-temperature side refrigerant circulation rate, and the fan air volume. Specifically, as shown in FIG. 9, the temperature efficiency threshold is set to be smaller as the refrigerant circulation rate increases. As a result, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is about 0.05 to 0.10 when the fan air volume is 40%. As shown in FIG. 14, the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε are determined more than the“ temperature efficiency ε determination threshold value εline ”is a constant value. The difference of the “threshold value εline” is improved. However, the difference between “the temperature efficiency value when the refrigerant amount is properly sealed” and “the determination threshold value εline of the temperature efficiency ε” is about 0.20 to 0.30 under the condition that the fan air volume is 100%. The difference is improved as compared with the case where “the determination threshold value εline of the temperature efficiency ε” in FIG.

  Where the refrigerant circulation rate is

となる。圧縮機吸入冷媒密度は圧縮機吸入圧力と圧縮機吸入温度により決まるから

It becomes. Compressor suction refrigerant density is determined by compressor suction pressure and compressor suction temperature

となる。ここでｆ（ ）は（ ）内の値をパラメータとする関数を表す。よって冷凍装置１の吸入温度センサ３３ａ、吸入圧力センサ３４ａにより冷媒密度を算出し、圧縮機運転周波数と定数２により冷媒循環量が算出される。圧縮機が複数台ある場合はそれぞれの圧縮機の冷媒循環量を合計した値を算出する。

It becomes. Here, f () represents a function using the value in () as a parameter. Therefore, the refrigerant density is calculated by the intake temperature sensor 33a and the intake pressure sensor 34a of the refrigeration apparatus 1, and the refrigerant circulation amount is calculated by the compressor operating frequency and the constant 2. When there are a plurality of compressors, the total value of the refrigerant circulation amount of each compressor is calculated.

  In order to derive the refrigerant circulation amount, it is necessary to perform a complicated calculation by the controller. Therefore, although the accuracy is slightly lowered, the threshold value may be determined using the refrigerant circulation amount based on the saturated suction refrigerant density calculated using only the suction pressure sensor 34a and the compressor operating frequency. Although the accuracy is further lowered, the threshold value may be determined simply based on only the total value of the compressor operating frequencies, or the threshold value may be changed only based on the low pressure. Even in these cases, the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε judgment threshold value”, compared with the case where the “temperature efficiency ε judgment threshold value εline” is a constant value. The difference in “εline” is improved.

[Threshold setting method 3 according to operating conditions]
As described above, the temperature efficiency varies depending on the variation of the high pressure. Therefore, in the refrigeration apparatus 1, the threshold value is changed by the high pressure as “threshold setting method 3”. FIG. 10 is a diagram for explaining an example of the relationship between the temperature efficiency value, the high pressure, and the operating frequency of the refrigeration apparatus according to the embodiment of the present invention. Specifically, as shown in FIG. 10, the temperature efficiency threshold is set to be smaller as the high pressure is decreased. As a result, under the condition of the compressor operating frequency of 100 Hz, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is about 0.05 to 0.10. Thus, as shown in FIG. 14, the difference is improved as compared with the case where “the determination threshold value εline of the temperature efficiency ε” is a constant value. However, at the compressor operating frequency of 30 Hz, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is about 0.20 to 0.30. The difference is improved as compared with the case where the “threshold value εline for temperature efficiency ε” of 14 is a constant value, but the difference is larger than the condition of the compressor operating frequency of 100 Hz.

[Threshold setting method 4 according to operating conditions]
As described above, the temperature efficiency varies depending on both the air flow rate and the refrigerant circulation amount. Further, ΔT defined by the following (Equation 7) also varies depending on both the air flow rate and the refrigerant circulation amount.

  When the air flow rate decreases, ΔT also increases because the condenser outlet temperature increases. At this time, the temperature efficiency decreases. Further, when the amount of refrigerant circulation increases, the amount of heat processed by the condenser increases, so the condenser outlet temperature increases and ΔT also increases. At this time, the temperature efficiency decreases. As ΔT increases, the temperature efficiency decreases, and as ΔT decreases, the temperature efficiency increases.

  Therefore, in the present embodiment, the threshold value is changed by ΔT as “threshold setting method 4 according to operating conditions”. FIG. 15 is a diagram for explaining an example of the relationship between the temperature efficiency value and ΔT of the refrigeration apparatus according to the embodiment of the present invention. Specifically, as shown in FIG. 15, the temperature efficiency threshold is set to be smaller as ΔT increases. As a result, even if the fan output and the operating frequency fluctuate, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is 0.05 to 0. 0. As shown in FIG. 14, the difference is greatly improved as compared with the case where “the determination threshold value εline of the temperature efficiency ε” is a constant value as shown in FIG. Further, even when compared with the threshold setting methods 1 to 3 depending on the operating conditions, the difference between the “temperature efficiency value when the refrigerant amount is properly sealed” and the “temperature efficiency ε determination threshold εline” is the largest. Therefore, the shortage of refrigerant can be detected with the most appropriate amount of refrigerant leakage.

[Refrigerant amount judgment operation]
FIG. 11 is a flowchart showing the procedure of the refrigerant quantity determination operation in the present embodiment. The refrigerant amount determination operation shown in FIG. 11 is executed by the heat source side control unit 31 of the refrigeration apparatus 1. The refrigeration apparatus 1 according to the present embodiment determines the refrigerant amount using the temperature efficiency ε of the first subcooler 22. Note that the determination of the refrigerant amount described below can also be applied to a refrigerant charging operation when the refrigeration apparatus 1 is installed or a refrigerant charging operation when the refrigeration apparatus 1 is maintained. The refrigerant amount determination operation may be executed when an instruction from a remote device (not shown) is received.

  In step ST1, normal operation control is started. In the normal operation control of the refrigeration apparatus 1, for example, the heat source side control unit 31 acquires operation data such as the pressure and temperature of the refrigerant circuit 10 detected by the sensors, and uses the operation data to condense the condensation temperature, the evaporation temperature, and the like. The control values such as target value and deviation are calculated to control the actuators. Hereinafter, the operation of the actuators will be described.

  For example, the heat source side control unit 31 controls the operating frequency of the compressor 21 so that the evaporation temperature of the refrigeration cycle of the refrigeration apparatus 1 matches the target temperature (for example, 0 ° C.). The evaporation temperature of the refrigeration cycle can also be obtained by converting the pressure detected by the suction pressure sensor 34a into a saturation temperature. For example, the heat source side control unit 31 increases the operation frequency of the compressor 21 when the current evaporation temperature is higher than the target temperature, and operates the compressor 21 when the current evaporation temperature is lower than the target value. Reduce the frequency.

  Further, for example, the heat source side control unit 31 blows air to the heat source side heat exchanger 23 so that the condensation temperature of the refrigeration cycle of the refrigeration apparatus 1 matches a target temperature (for example, 45 ° C.). Control the number of revolutions. The condensation temperature of the refrigeration cycle of the refrigeration apparatus 1 can also be obtained by converting the pressure detected by the discharge pressure sensor 34b into a saturation temperature. For example, the heat source side control unit 31 increases the number of rotations of the heat source side fan 27 when the current condensing temperature is higher than the target temperature, and increases the rotational speed of the heat source side fan 27 when the current condensing temperature is lower than the target temperature. Reduce the rotation speed.

  Further, for example, the heat source side control unit 31 adjusts the opening degree of the injection amount adjustment valve 72 of the first injection circuit 71 using a signal obtained from the sensors. For example, the heat source side control unit 31 opens the injection amount adjustment valve 72 when the current discharge temperature of the compressor 21 is high, and sets the injection amount adjustment valve 72 when the current discharge temperature of the compressor 21 is low. Close. Further, for example, the heat source side control unit 31 controls the rotation speed of the use side fan 43 that blows air to the use side unit 4.

  In step ST2, the heat source side control unit 31, for example, the outlet temperature of the heat source side heat exchanger 23, the temperature of the outlet of the first subcooler 22, the outside air temperature detected by the suction outside air temperature sensor 33c and the discharge pressure sensor 34b. Is used to calculate the temperature efficiency ε of the first subcooler 22.

In step ST3, the heat source side control unit 31 acquires the operating state of the refrigeration apparatus 1. The heat source side control unit 31 determines whether or not the current operation state corresponds to an exception condition for refrigerant amount determination. As exception conditions for this refrigerant quantity determination, for example, the following conditions are set in advance. When it corresponds to any one of these, it judges that it corresponds to the exceptional condition of refrigerant | coolant amount determination.
・ When the compressor 21 is stopped.
-30 minutes after startup (because temperature efficiency ε is not stable).
-In the case of low outside air temperature (at low outside air temperature, the fan air volume is reduced because it tries to maintain high pressure. Therefore, the temperature efficiency ε also decreases, which may cause false detection).
・ At high outside temperatures that are outside the operating range.
・ When the temperature difference between the condensation temperature and outside temperature is large.
-When the temperature efficiency ε may be below the threshold due to the condensation temperature, the temperature difference between the condensation temperature and the outside air temperature, or the influence of the outside air temperature.
-When the superheat is small (even if there is no surplus refrigerant in the liquid reservoir, there is a possibility that there is surplus refrigerant in the accumulator 24 and there is no refrigerant leakage).
In such a case, the value of the temperature efficiency ε becomes small and erroneous detection occurs.

  When the operating state of the refrigeration apparatus 1 corresponds to the “exception condition for refrigerant amount determination”, the process returns to step ST1, and the operating state of the refrigeration apparatus 1 corresponds to the “exception condition for refrigerant amount determination”. If not, the process proceeds to step ST4.

  In step ST4, the heat source side control unit 31 determines whether or not the operation control of the refrigeration apparatus 1 started in step ST1 is stably executed. FIG. 12 is a conceptual diagram for explaining stability determination conditions in the embodiment of the present invention. The stability determination condition is set such that the plurality of temperature efficiencies ε calculated in step ST2 and the operation frequency at that time do not vary greatly. For example, as the stability determination condition, it is determined that the stability determination condition is satisfied when the frequency of the compressor 21 satisfies the following condition (8) and when the temperature efficiency ε satisfies the following condition (9). . That is, as shown in FIG. 12A, when all the changes from the average value of the target data fall within the predetermined value (η) (open circles), it is determined that the stability determination condition is satisfied. On the other hand, as shown in FIG. 12B, when at least one of the changes from the average value of the target data exceeds a predetermined value (η) (black circle mark), it is determined that the stability determination condition is not satisfied. Thus, by calculating the average temperature efficiency εA in a state where the calculated temperature efficiency ε and the operating frequency of the compressor 21 are stable, the refrigerant amount can be determined with higher accuracy.

  If the operation control of the refrigeration apparatus 1 is not stable, the process returns to step ST1, and if the operation control of the refrigeration apparatus 1 is stable, the process proceeds to step ST5.

  In step ST5, the heat source side control unit 31 determines whether or not the refrigerant amount is appropriate by comparing the refrigerant amount determination parameter with its reference value. Specifically, a deviation amount ΔT (= T−Tm) between the temperature efficiency ε of the first subcooler 22 and the determination threshold value Tm is obtained, and it is determined whether or not the deviation amount ΔT is a positive value. If the deviation amount ΔT is positive, the heat source side control unit 31 determines that the refrigerant amount is not insufficient, and proceeds to step ST6. If the deviation amount ΔT is negative, the heat source side control unit 31 determines that the refrigerant amount is insufficient, and proceeds to step ST7. At this time, the temperature efficiency ε of the first subcooler 22 is preferably a moving average of a plurality of temperature efficiencies ε that are temporally different from each other, rather than using an instantaneous value. The stability of the refrigeration cycle can also be taken into account by taking a moving average of a plurality of temperature efficiencies ε that are temporally different. The determination threshold value Tm may be stored in advance in the storage unit 3c of the heat source side control unit 31, for example, or may be set by input from a remote controller or a switch, or from a remote device (not shown). May be set according to the instruction.

  When the refrigerant amount determination result in step ST5 indicates that the refrigerant amount is appropriate, the heat source side control unit 31 outputs in step ST6 that the refrigerant amount is appropriate. When the amount of refrigerant is appropriate, the fact that the amount of refrigerant is appropriate is displayed, for example, on a display unit (not shown) such as an LED or a liquid crystal disposed in the refrigeration apparatus 1, or the amount of refrigerant is appropriate. Is transmitted to a remote device (not shown).

  When the refrigerant amount determination result in step ST5 is that the refrigerant amount is insufficient, the heat source side control unit 31 outputs in step ST7 that the refrigerant amount is insufficient. When the refrigerant amount is insufficient, for example, an alarm indicating that the refrigerant amount is insufficient is displayed on a display unit (not shown) such as an LED or a liquid crystal provided in the refrigeration apparatus 1, or A signal indicating that the amount of refrigerant is insufficient is transmitted to a remote device (not shown). In addition, since an emergency may be required when the amount of refrigerant is insufficient, it may be configured to notify the service person directly of the occurrence of an abnormality through a telephone line or the like.

  In the above embodiment, after calculating the temperature efficiency ε in step ST2, it is determined in step ST3 whether or not the operating state of the refrigeration apparatus 1 satisfies the exceptional condition, and in step ST4, the refrigeration apparatus. Although it is determined whether or not the refrigerant amount is determined by determining whether or not the operation control of 1 is stable, the present invention is not limited to this. Step ST2 may be executed after step ST3 and step ST4. By performing the calculation of the temperature efficiency ε after determining whether or not to determine the refrigerant amount, the processing amount that the heat source side control unit 31 performs the calculation can be reduced.

  As described above, in the present embodiment, the temperature efficiency ε is used to determine whether or not the refrigerant circuit 10 of the refrigeration apparatus 1 has a shortage of refrigerant. Even in this case, leakage of the refrigerant can be detected at an early stage.

  Furthermore, in the present embodiment, the operating state of the refrigeration apparatus 1 is acquired, and the temperature efficiency threshold for determining the refrigerant shortage using the temperature efficiency ε of the refrigeration apparatus 1 is the operation of the refrigeration apparatus 1. It changes according to the state. Therefore, the determination can be made with as little refrigerant shortage and leakage as possible, and the refrigerant shortage determination is performed earlier than the conventional method. As a result, the rise in the internal temperature can be reduced as much as possible, and the deterioration of the global environment can be reduced, the damage to the stored items due to the increase in the internal temperature when the refrigerant leaks, and the recovery cost after the refrigerant leaks. Further, since the temperature efficiency threshold value can be changed and determined with a small number of parameters, the determination can be made with as little refrigerant shortage and leakage as possible with simpler control.

  In the operation control described above, control for specifying the condensation temperature and the evaporation temperature is not performed. However, for example, the control may be performed so that the condensation temperature and the evaporation temperature are constant. Further, for example, it is not necessary to control the condensing temperature and the evaporating temperature by setting the operating frequency of the compressor 21 and the rotation speed of the heat source side fan 27 of the heat source side unit 2 as constant values. Further, for example, the control may be performed so that one of the condensation temperature and the evaporation temperature becomes a target value. By controlling the operating state of the refrigeration apparatus 1 to a certain condition, the degree of subcooling of the first subcooler 22 and the fluctuation of the operating state quantity that varies according to the degree of subcooling are reduced, and the threshold value is determined. It becomes easy, and it becomes easy to determine whether the amount of refrigerant is insufficient.

  Further, the refrigerant amount determination operation of the present embodiment is applied to the refrigerant charging operation at the initial stage of installation of the refrigeration apparatus 1 or the refrigerant charging operation when the refrigerant is once discharged and charged again at the time of maintenance. It is possible to reduce the time required for the operator and reduce the load on the worker.

[Modification]
FIG. 13 is a diagram schematically illustrating a refrigerant circuit of a refrigeration apparatus according to a modification of the present invention. Compared with the refrigeration apparatus 1 shown in FIG. 1, the heat source side unit 2A of the refrigeration apparatus 1A of the modification has a second subcooler 26 instead of the first subcooler 22 as shown in FIG. doing. The second subcooler 26 corresponds to the “supercooler” of the present invention. The second subcooler 26 includes, for example, a double-tube subcooler or a plate heat exchanger, and includes a high-pressure refrigerant flowing in the heat source side refrigerant circuit 10b and an intermediate pressure flowing in the first injection circuit 71A. Heat exchange with the other refrigerant. A part of the refrigerant that has passed through the second subcooler 26 is expanded by the injection amount adjustment valve 72 to become an intermediate-pressure refrigerant, and exchanges heat with the refrigerant that has passed through the second subcooler 26. Further, the intermediate-pressure refrigerant that flows in from the injection amount adjustment valve 72 and exchanges heat with the second subcooler 26 becomes a refrigerant having a high dryness, so that the discharge temperature of the compressor 21 is lowered in order to lower the discharge temperature of the compressor 21. Injection into the suction side. The refrigerant determination operation in the modification is performed using the temperature efficiency of the second subcooler 26.

  In the case of a second subcooler using a double pipe supercooler or a plate heat exchanger in which the high temperature side is a refrigerant and the low temperature side is also a refrigerant fluid, the temperature efficiency is the refrigerant at the outlet of the second subcooler 26. Is a value obtained by dividing the degree of supercooling (condenser outlet temperature-supercooling heatr outlet temperature) by the maximum temperature difference of the second supercooler 26 (condenser outlet temperature-intermediate pressure (injection circuit) saturation temperature). . The temperature efficiency is expressed by the following (Formula 10).

  In addition, in a modification, the 1st subcooler 22 can be added and the refrigerant | coolant which flowed out from the receiver 25 can also be set as the structure which flows in into the 2nd subcooler 26 after passing the 1st subcooler 22. FIG.

  As described above, the temperature efficiency of the heat exchanger is generally expressed by the above (Equation 4). For convenience of explanation, (Formula 4) is described again.

The modified second subcooler 26 exchanges heat between the refrigerant and the refrigerant, and the high-temperature side fluid is the refrigerant, and the low-temperature side fluid is also the refrigerant. Therefore, K: heat passage rate (W / (m ² · K)) varies depending on the refrigerant circulation amount. The temperature efficiency decreases as the refrigerant circulation rate increases.

ρm · Vm: Low temperature side fluid density (kg / m ³ ) × Low temperature side fluid volume flow rate (m ³ / h) is the low temperature side refrigerant circulation amount Gm (kg / h) flowing through the first injection circuit 71A, When the refrigerant circulation amount Gm increases, the temperature efficiency decreases. The refrigerant circulation amount Gm flowing through the first injection circuit 71A varies depending on the opening degree of the injection amount adjusting valve 72 and the differential pressure upstream and downstream of the injection amount adjusting valve 72.

  Cm: Low temperature side fluid specific heat (KJ / kg) fluctuates due to the intermediate pressure of the refrigerant (pressure downstream of the injection amount adjusting valve 72), and the temperature efficiency decreases as the intermediate pressure increases. Other parameters are as described for the temperature efficiency of the first subcooler 22 of the embodiment.

From the above, A (heat transfer area) is a constant value unique to the refrigeration apparatus 1A. The temperature efficiency is defined as the high-temperature side refrigerant circulation amount that fluctuates the heat transfer rate (K), the low-temperature side refrigerant circulation amount that flows through the first injection circuit 71A,
It fluctuates depending on the high-pressure pressure that changes the high-temperature side fluid specific heat (Ch) and the intermediate pressure. Therefore, when the temperature efficiency threshold value is changed according to the operating conditions, the temperature efficiency threshold value, the low temperature side refrigerant circulation rate, the high pressure pressure, and the intermediate pressure are set. Note that the high-temperature side refrigerant circulation amount varies depending on the compressor frequency, the refrigerant compressor intake gas pressure, and the compressor intake gas temperature. The low-temperature side refrigerant circulation amount varies depending on the opening degree of the injection amount adjusting valve 72 and the differential pressure between the upstream and downstream of the injection amount adjusting valve 72.

  Also in the case of the modification, when the temperature efficiency is set by the high-temperature side refrigerant circulation amount and the high pressure, the above-mentioned [Threshold setting method 2 by operating conditions] and [Threshold setting method 3 by operating conditions] are used, respectively. Can do.

[Threshold setting method 5 according to operating conditions]
As described above, the temperature efficiency fluctuates due to the fluctuation of the low temperature side refrigerant circulation rate. Therefore, in the present embodiment, the threshold value is changed according to the low-temperature side refrigerant circulation amount as “threshold value setting method 5 based on operating conditions”. Specifically, as in FIG. 9, the temperature efficiency threshold is set to be smaller as the low-temperature-side refrigerant circulation rate increases. Thereby, as shown in FIG. 14, the difference is improved as compared with the case where “the determination threshold value εline of the temperature efficiency ε” is a constant value.

  Here, the low-temperature-side refrigerant circulation amount is obtained from the following (Formula 11).

  Therefore, if the injection amount adjusting valve 72 of the refrigeration apparatus 1 is an electronic expansion valve, the control unit 3 outputs the opening degree of the injection amount adjusting valve 72, the differential pressure between the upstream and downstream of the injection amount adjusting valve 72, and the injection amount adjustment. The low-temperature side refrigerant circulation amount is calculated from the pressure and temperature upstream of the valve 72. If there is no pressure sensor at 71A downstream of the injection amount adjusting valve 72, the pressure may be calculated from the suction pressure sensor 34a and the discharge pressure sensor 34b.

  In order to derive the refrigerant circulation amount, it is necessary to perform a complicated calculation by the controller. Therefore, although the accuracy is slightly reduced, for simplicity, either a value for outputting the opening degree of the injection amount adjusting valve 72, a differential pressure between the upstream and downstream of the injection amount adjusting valve 72, or a pressure upstream of the injection amount adjusting valve 72 is used. The threshold may be determined using one or more of the parameters.

  Further, the suction pressure sensor 34a and the discharge pressure sensor 34b are simply used in place of the differential pressure between the upstream and downstream of the injection amount adjusting valve 72, and the suction pressure and discharge pressure of the compressor expressed by the following formula 12 are used. The threshold value may be changed using the compression ratio as a parameter.

  Further, the threshold value may be changed with the temperature difference between the upstream and downstream of the injection amount adjusting valve 72 or the pressure ratio between the upstream and downstream of the injection amount adjusting valve 72 as a parameter. Further, the threshold value may be changed using the density upstream of the injection amount adjusting valve 72 as a parameter.

  Further, the degree of opening of the injection amount adjusting valve 72, the differential pressure between the upstream and downstream of the injection amount adjusting valve 72, the density upstream of the injection amount adjusting valve 72, the pressure upstream of the injection amount adjusting valve 72, and the injection amount. The threshold value may be changed using any one of the temperatures upstream of the regulating valve 72 as a parameter, or the threshold value may be changed using a plurality of these as parameters.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. That is, the configuration of the above embodiment may be improved as appropriate, or at least a part of the configuration may be replaced with another configuration. Further, the configuration requirements that are not particularly limited with respect to the arrangement are not limited to the arrangement disclosed in the embodiment, and can be arranged at a position where the function can be achieved.

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus, 1A refrigeration apparatus, 2 heat source side unit, 2A heat source side unit, 3 control part, 3a acquisition part, 3b calculating part, 3c memory | storage part, 3d drive part, 3e input part, 3f
Output unit, 4 use side unit, 5 supercooling heat exchanger, 6 liquid refrigerant extension pipe, 7 gas refrigerant extension pipe, 10 refrigerant circuit, 10a use side refrigerant circuit, 10b heat source side refrigerant circuit, 21
Compressor, 22 1st subcooler, 23 Heat source side heat exchanger, 24 Accumulator, 25 Receiver, 26 2nd subcooler, 27 Heat source side fan, 28 Liquid side shutoff valve, 29 Gas side shutoff valve, 31 Heat source side Control unit, 32 Use side control unit, 33a Suction temperature sensor, 33b Discharge temperature sensor, 33c Suction outside air temperature sensor, 33d Supercooler high pressure side outlet temperature sensor, 33e Use side heat exchange inlet temperature sensor, 33f Use side heat exchange outlet Temperature sensor, 33 g Suction air temperature sensor, 34 a Suction pressure sensor, 34 b Discharge pressure sensor, 41 Usage side expansion valve, 42 Usage side heat exchanger, 43 Usage side fan, 71 1st injection circuit, 71 A 1st injection circuit, 72 Injection amount adjusting valve, 73 Second injection circuit, 74 Capillary tube, 75 Suction injection Solenoid valve, T temperature efficiency, T1 temperature efficiency threshold, T2 temperature efficiency threshold, T3 temperature efficiency threshold.

Claims (9)

A heat source side unit having a compressor, a heat source side heat exchanger, a heat source side fan for blowing air to the heat source side heat exchanger, a subcooler, a use side expansion valve, and a use side heat exchanger; And a refrigeration apparatus having a refrigerant circuit that is connected to the at least one usage-side unit by a pipe and circulates the refrigerant,
The temperature efficiency of the subcooler, which is a value obtained by dividing the degree of supercooling of the refrigerant on the outlet side of the subcooler by the maximum temperature difference between the high temperature side fluid and the low temperature side fluid that are heat-exchanged by the subcooler, Using a refrigerant shortage determination unit for determining the shortage of the refrigerant amount filled in the refrigerant circuit,
The refrigerant shortage determining unit is a refrigeration apparatus that compares the temperature efficiency of the supercooler with a temperature efficiency threshold that is changed according to an operating state of the refrigeration apparatus, and determines whether the refrigerant amount is insufficient.   The refrigeration apparatus according to claim 1, wherein the refrigerant shortage determination unit changes the temperature efficiency threshold based on the maximum temperature difference. In the subcooler, the low temperature side fluid is air,
The refrigerant shortage determination unit changes the temperature efficiency threshold using one or more of a pressure of the refrigerant that is the high temperature side fluid, a circulation amount of the refrigerant that is the high temperature side fluid, and an air flow rate as a parameter. The refrigeration apparatus according to 1. The refrigeration apparatus further branches from a downstream side of the heat source side heat exchanger, and is connected to an intermediate pressure port of the compressor or a suction side of the compressor, and an injection amount provided in the injection pipe A regulating valve,
The injection pipe is connected to the compressor via the subcooler downstream of the injection amount adjustment valve, and the refrigerant that has flowed out of the heat source side heat exchanger that is the high temperature side fluid in the subcooler; The refrigerant that has flowed into the injection pipe that is the low temperature side fluid is configured to exchange heat,
The refrigerant shortage determination unit includes the temperature efficiency threshold value using one or more of a refrigerant pressure of the high temperature side fluid, a circulation amount of the refrigerant of the high temperature side fluid, and a circulation amount of the refrigerant of the low temperature side fluid as parameters. The refrigeration apparatus of Claim 1 which changes.   5. The refrigeration apparatus according to claim 3, wherein the refrigerant shortage determination unit changes the temperature efficiency threshold value small when a circulation amount of the refrigerant of the high temperature side fluid increases.   The refrigerant shortage determination unit changes the temperature efficiency threshold based on a frequency of the compressor or a suction density of the compressor used for calculating a circulation amount of the refrigerant of the high temperature side fluid. The refrigeration apparatus described in 1.   The said refrigerant | coolant shortage determination part changes the said temperature efficiency threshold value based on the suction pressure of the said compressor used for calculation of the suction density of the said compressor, or the suction temperature of the said compressor. Refrigeration equipment.   The refrigeration apparatus according to claim 3, wherein the refrigerant shortage determination unit changes the temperature efficiency threshold value small when an output ratio of the heat source side fan that fluctuates the air flow rate decreases.   The refrigerant shortage determination unit includes an opening degree of the injection amount adjusting valve, a differential pressure between the upstream and downstream of the injection amount adjusting valve, a density upstream of the injection amount adjusting valve, a pressure upstream of the injection amount adjusting valve, 5. The refrigeration apparatus according to claim 4, wherein the temperature efficiency threshold value is changed using any one or more of temperatures upstream of the injection amount adjustment valve as a parameter.

Images