JP6848027B2 - Refrigeration equipment - Google Patents

Description

The present invention relates to a refrigerating apparatus for determining the amount of refrigerant in a refrigerant circuit.

In an air conditioner such as a refrigerating device, if an excess or deficiency of the amount of refrigerant occurs, the capacity of the refrigerating device may be reduced or the constituent equipment may be damaged. Therefore, in order to prevent the occurrence of such a problem, some have a function of determining the excess or deficiency of the amount of the refrigerant filled in the freezing device.

As a method for determining the refrigerant shortage in the conventional refrigerating 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 overcooling heat exchanger in which the high temperature side is the refrigerant and the low temperature side is the fluid of air, the temperature efficiency is that the degree of overcooling of the refrigerant at the outlet of the supercooling heat exchanger is overcooled. It is stated that the value is divided by the maximum temperature difference of the heat exchanger. Further, 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 temperature of the outlet of the supercooling heat exchanger from the outlet temperature of the condenser, and is the maximum temperature of the supercooling heat exchanger. It is stated that the difference is the value obtained by subtracting the outside air temperature from the condenser outlet temperature. The outlet temperature of the condenser is TH5, the outlet temperature of the supercooled heat exchanger is TH8, the outside air temperature is TH6, and the temperature efficiency ε of the supercooled heat exchanger is expressed by the following (Formula 2).

When a refrigerant leaks, the extent to which the refrigerant leaks can be judged is generally "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value of temperature efficiency ε". It changes depending on the difference of "εline". That is, when the difference between the "value of the temperature efficiency when the amount of the refrigerant is properly filled" and the "determination threshold value εline of the temperature efficiency ε" is large, the refrigerant shortage cannot be determined unless a large amount of refrigerant leaks. On the contrary, when the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is small, it is possible to judge the refrigerant shortage with a small amount of refrigerant leakage. it can.

Japanese Unexamined Patent Publication No. 2012-132739

However, in the refrigerating apparatus described in Patent Document 1, since the value of the temperature efficiency when the amount of the refrigerant is properly sealed changes depending on the operating frequency, the evaporation temperature and the fan air volume value, "the amount of the refrigerant is properly sealed. The difference between "the value of the temperature efficiency when the temperature efficiency is set to" and "the judgment threshold value εline of the temperature efficiency ε" changes depending on the operating conditions. Therefore, depending on the operating conditions, it may not be possible to determine the refrigerant shortage 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 amount of refrigerant is properly filled” is 0.45, and the “temperature efficiency ε is determined”. Since the value εline ”(“ threshold value ”indicated by the 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, the "temperature efficiency value when the amount of refrigerant is properly filled" is 0.80, and the "temperature efficiency ε judgment threshold value εline" is 0. Since it is .40, the difference is as large as 0.40, and the refrigerant shortage cannot be detected unless a large amount of refrigerant leaks.

In the judgment using the temperature efficiency, the change due to the operating conditions of the refrigerating apparatus is smaller than the judgment using the change in the degree of supercooling to judge the shortage of the refrigerant amount, but the difference in the temperature efficiency due to the above operating conditions occurs. .. In particular, the temperature range inside the showcase and unit cooler is about -50 to + 23 ° C, and the temperature range inside the refrigerator is larger than the temperature range of the air conditioner +15 to + 30 ° C, so the operating conditions change significantly. .. Not having a fixed condition mode such as the refrigerant shortage determination mode is also a reason why the conditions at the time of refrigerant shortage determination change significantly. As a result, depending on the operating conditions, it may not be possible to detect the refrigerant shortage unless a large amount of refrigerant leaks. If a large amount of refrigerant leakage is required to determine whether or not a refrigerant leakage has occurred, there is concern about the impact on the global environment such as global warming due to the refrigerant leakage. Further, if the amount of refrigerant leaked is large, the amount of the leaked amount is increased, so that there is a concern that the restoration cost will increase.

The present invention has been made against the background of the above problems, and an object of the present invention is to determine a refrigerant shortage based on a small amount of refrigerant shortage and leakage, and to shorten the time required for determining the refrigerant shortage. ..

The refrigerating apparatus according to the present invention includes a compressor, a heat source side heat exchanger, a heat source side unit having a heat source side fan for blowing air to the heat source side heat exchanger, and a supercooler, and a utilization side expansion valve. And at least one user-side unit having a user-side heat exchanger are connected by a pipe, and is a refrigerating device having a refrigerant circuit for circulating a refrigerant, and the refrigerant is used by using the temperature efficiency of the supercooler. A refrigerant shortage determination unit that determines the shortage of the amount of refrigerant filled in the circuit and an injection tube that branches from the downstream of the heat source side heat exchanger and is connected to the intermediate pressure port of the compressor or the suction side of the compressor. And an injection amount adjusting valve provided in the injection pipe, and the supercooler exchanges heat between the refrigerant flowing out from the heat source side heat exchanger and the refrigerant expanded by the injection amount adjusting valve. The refrigerant shortage determination unit determines that the amount of refrigerant is insufficient by comparing the temperature efficiency of the supercooler with the temperature efficiency threshold value that is changed according to the operating state of the refrigerating apparatus. The temperature efficiency threshold value is changed based on the operating state of the refrigerating apparatus , and the refrigerant shortage determination unit determines the opening degree of the injection amount adjusting valve and the upstream and downstream of the injection amount adjusting valve. The temperature efficiency threshold value is changed by using one or more of the differential pressure, the density upstream of the injection amount adjusting valve, the pressure upstream of the injection amount adjusting valve, and the temperature upstream of the injection amount adjusting valve as parameters. Is what you do.

According to the refrigerating 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 supercooler to determine the insufficient amount of refrigerant. ing. Therefore, it is possible to determine the insufficient amount of the refrigerant according to the operating state of the refrigerating apparatus, and it is possible to determine the insufficient amount of the refrigerant with a small amount of refrigerant leakage.

It is a figure which typically describes an example of the refrigerant circuit of the refrigerating apparatus which concerns on embodiment of this invention. It is a control block diagram of the refrigerating apparatus which concerns on embodiment of this invention. This is an example of a ph diagram when the amount of refrigerant is appropriate in the refrigerating apparatus shown in FIG. This is an example of a ph diagram when the amount of refrigerant is insufficient in the refrigerating apparatus shown in FIG. It is a figure explaining the relationship between the amount of refrigerant of the refrigerating apparatus described in FIG. 1, the degree of supercooling of the first supercooler, and the operating condition of a refrigerating apparatus. In the refrigerating apparatus shown in FIG. 1, 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 when the amount of the refrigerant is an appropriate amount is illustrated. is there. It is a figure explaining the relationship between the amount of refrigerant of the refrigerating apparatus of FIG. 1, the temperature efficiency of the first supercooler, and the operating condition of a refrigerating apparatus. It is a figure explaining an example of the relationship between the temperature efficiency value of the refrigerating 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 refrigerating apparatus which concerns on embodiment of this invention, the high temperature side refrigerant circulation amount, and a fan air volume. It is a figure explaining an example of the relationship between the temperature efficiency value of the refrigerating apparatus which concerns on embodiment of this invention, a high pressure pressure, and an operating frequency. It is a flowchart which shows the procedure of the refrigerant shortage determination operation in this embodiment. It is a conceptual diagram explaining the stability determination condition in embodiment of this invention. It is a figure which schematically described the refrigerant circuit of the refrigerating 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 the 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 refrigerating apparatus which concerns on embodiment of this invention, and ΔT.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. In addition, the shape, size, arrangement, etc. of the configurations shown in each figure can be appropriately changed within the scope of the present invention.

Embodiment.
[Refrigerator]
FIG. 1 is a diagram schematically showing an example of a refrigerant circuit of a refrigerating apparatus according to an embodiment of the present invention. The refrigerating apparatus 1 shown in FIG. 1 cools a room, a warehouse, a showcase, a refrigerator, or the like by performing a vapor compression refrigeration cycle operation. The refrigerating device 1 includes, for example, one heat source side unit 2 and two utilization side units 4 connected in parallel to the heat source side unit 2. By connecting the heat source side unit 2 and the utilization side unit 4 with the liquid refrigerant extension pipe 6 and the gas refrigerant extension pipe 7, a refrigerant circuit 10 for circulating the refrigerant is formed. The refrigerant filled in the refrigerant circuit 10 of this embodiment is, for example, R410A, which is an HFC-based mixed refrigerant. In the example of FIG. 1, one heat source side unit 2 and two user side units 4 are described, but the heat source side unit 2 may be two or more units, and the user side unit 4 may be used. May be 1 or 3 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 user-side units 4, the capacities of the plurality of user-side units 4 may be the same or different. In the following description, the refrigerating device 1 in which the refrigerant exchanges heat with air will be described, but the refrigerant may be a refrigerating device that exchanges heat with a fluid such as water, a refrigerant, or brine.

[User unit]
The user-side unit 4 is, for example, an indoor unit installed indoors, and includes a user-side refrigerant circuit 10a and a user-side control unit 32 that form a part of the refrigerant circuit 10. The user-side refrigerant circuit 10a includes a user-side expansion valve 41 and a user-side heat exchanger 42. The utilization-side expansion valve 41 adjusts the flow rate of the refrigerant flowing through the utilization-side refrigerant circuit 10a, and is composed of, for example, an electronic expansion valve or a temperature-type expansion valve. The utilization side expansion valve 41 may be arranged in the heat source side unit 2. In that case, the utilization side expansion valve 41 is, for example, the first supercooler 22 and the liquid side of the heat source side unit 2. It is arranged between the closing valve 28 and the shutoff valve 28. The user-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 for evaporating the refrigerant.

A user-side fan 43 that blows air to the user-side heat exchanger 42 is arranged in the vicinity of the user-side heat exchanger 42. The user-side fan 43 includes, for example, a centrifugal fan, a multi-blade fan, or the like, and is driven by a motor (not shown). The user-side fan 43 can adjust the amount of air blown to the user-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 form a part of the refrigerant circuit 10.

The heat source side refrigerant circuit 10b includes a compressor 21, a heat source side heat exchanger 23, a receiver 25, a first supercooler 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 user side heat exchanger 42 from the heat source side refrigerant circuit 10b and returns it to the intermediate pressure portion of the compressor 21. , The injection amount adjusting valve 72 is included.

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

The heat source side heat exchanger 23 is, for example, a fin and tube type heat exchanger configured to include a heat transfer tube and a large number of fins, and functions as a condenser for condensing the refrigerant. A heat source side fan 27 that blows air to the heat source side heat exchanger 23 is arranged in the vicinity of the heat source side heat exchanger 23. The heat source side fan 27 blows the 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 is configured to include, for example, a centrifugal fan or a multi-blade 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 arranged between the heat source side heat exchanger 23 and the first supercooler 22 to store the surplus liquid refrigerant, for example, a container for storing the surplus liquid refrigerant. The excess liquid refrigerant is generated in the refrigerant circuit 10 according to, for example, the size of the load of the user-side unit 4, the condensation temperature of the refrigerant, the outside air temperature, the evaporation temperature, the capacity of the compressor 21, and the like. ..

The first supercooler 22 exchanges heat between the refrigerant and air, and is integrally formed 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 supercooler 22. The first supercooler 22 corresponds to the "supercooler" of the present invention. The first supercooler 22 and the heat source side heat exchanger 23 may be configured separately. In that case, a fan (not shown) for blowing air to the first supercooler 22 is arranged in the vicinity of the first supercooler 22.

The liquid side closing valve 28 and the gas side closing valve 29 are composed of valves that open and close, such as a ball valve, an on-off valve, and an operating valve.

In the example shown in FIG. 1, the inlet of the first injection circuit 71 is connected between the first supercooler 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 supercooler 22, may be connected to the receiver 25, or may be connected between the heat source side heat exchanger 23 and the receiver 25. ..

[Controls and sensors]
Next, the control unit and the sensors included in the refrigerating device 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 microprocessor, a memory, and the like. Further, the user-side unit 4 includes a user-side control unit 32 that controls the user-side unit 4. The user-side control unit 32 includes a microprocessor, a memory, and the like. The user-side control unit 32 and the heat source-side control unit 31 can communicate with each other to exchange control signals. For example, the user-side control unit 32 issues an instruction from the heat source-side control unit 31. In response, the user unit 4 is controlled.

The refrigerating apparatus 1 according to this embodiment includes a suction 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 user side heat exchange inlet temperature sensor 33e, and a user 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 arranged in the heat source side unit 2 and are controlled by the heat source side. It is connected to the unit 31. The user-side heat exchange inlet temperature sensor 33e, the user-side heat exchange outlet temperature sensor 33f, and the suction air temperature sensor 33 g are arranged in the user-side unit 4 and connected to the user-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 by the compressor 21. The supercooler high pressure side outlet temperature sensor 33d detects the temperature of the refrigerant that has passed through the first supercooler 22. The user-side heat exchange inlet temperature sensor 33e detects the evaporation temperature of the gas-liquid two-phase refrigerant flowing into the user-side heat exchanger 42. The user-side heat exchange outlet temperature sensor 33f detects the temperature of the refrigerant flowing out from the user-side heat exchanger 42. The sensor for detecting the temperature of the refrigerant is arranged, for example, in contact with the refrigerant pipe or inserted into the refrigerant pipe to detect the temperature of the refrigerant.

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

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

In the example of this 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 disposing a temperature sensor on the heat source side heat exchanger 23.

FIG. 2 is a control block diagram of the refrigerating apparatus according to the embodiment of the present invention. The control unit 3 controls the entire refrigerating device 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 shortage 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 controls the drive of the compressor 21, valves, fans, etc. by using the result calculated by the calculation unit 3b. The storage unit 3c stores the physical property values of the refrigerant (saturation pressure, saturation temperature, etc.), data for the calculation unit 3b to perform calculations, and the like. The calculation unit 3b can refer to or update the stored contents of the storage unit 3c as needed.

Further, the control unit 3 includes an input unit 3e and an output unit 3f. The input unit 3e inputs an operation input from a remote controller or switches (not shown), or inputs communication data from a 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 means (not shown) such as an LED or a monitor and outputs it to a notification means (not shown) such as a speaker, or a telephone line or a LAN line. It is output to a communication means (not shown) such as. When the information is output to a remote location by the communication means, it is preferable that both the refrigerating device 1 and the remote device (not shown) are provided with communication means (not shown) having the same communication protocol.

For example, the refrigerating device 1 and the remote device (not shown) can be used to determine whether the amount of refrigerant is insufficient or the like. In that case, for example, the calculation unit 3b calculates the temperature efficiency ε of the first supercooler 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 includes a refrigerant shortage determination means (not shown) for determining a refrigerant shortage, and determines the refrigerant shortage using the temperature efficiency ε. By managing the refrigerant shortage information and the like with the remote device, it is possible to detect an abnormality of the refrigerating device 1 at an early stage at the place where the remote device is installed, so that when an abnormality occurs in the refrigerating device 1, etc. , Maintenance of the freezing device 1 can be performed at an early stage.

In the above description, an example in which the control unit 3 is included in the heat source side control unit 31 has been described, but the control unit 3 may be included in the user side control unit 32, or the heat source. The side control unit 31 and the user side control unit 32 may have a separate configuration.

[Operation of refrigeration equipment (when the amount of refrigerant is appropriate)]
FIG. 3 is an example of a ph diagram when the amount of refrigerant is appropriate in the refrigerating apparatus shown in FIG. First, the operation of the refrigerating apparatus 1 when the amount of the refrigerant is appropriate will be described. From point K to point L in FIG. 3, the compressor 21 shown in FIG. 1 compresses the refrigerant. From points L to 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 that functions as a condenser to be condensed and liquefied. The refrigerant that has been heat-exchanged by the heat source side heat exchanger 23 and is 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 changes according to the operating load of the user-side unit 4, the outside air temperature, the condensation temperature, and the like.

From point M to point N in FIG. 3, the liquid refrigerant stored in the receiver 25 in FIG. 1 is supercooled by the first supercooler 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.

From point N to point O in FIG. 3, the liquid refrigerant supercooled by the first supercooler 22 in FIG. 1 passes through the liquid side closing valve 28 and the liquid refrigerant extension pipe 6 to the user side unit 4. It is sent and depressurized by the expansion valve 41 on the utilization side to become a low-pressure gas-liquid two-phase refrigerant.

From point O to point K in FIG. 3, the gas-liquid two-phase refrigerant decompressed by the utilization-side expansion valve 41 in FIG. 1 is gasified by the utilization-side heat exchanger 42 that functions as an evaporator. The degree of superheat of the refrigerant is calculated by subtracting the evaporation temperature of the refrigerant detected by the user-side heat exchange inlet temperature sensor 33e from the temperature detected by the user-side heat exchange outlet temperature sensor 33f. The gas refrigerant gasified by the user-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 portion of the compressor 21. The inlet of the first injection circuit 71 is connected between the outlet of the first supercooler 22 and the liquid side closing valve 28, and a part of the high-pressure liquid refrigerant supercooled by the first supercooler 22 is used. , The pressure is reduced by the injection amount adjusting valve 72 to become an intermediate pressure two-phase refrigerant, which flows into the injection portion of the compressor 21.

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

When the amount of refrigerant is further reduced and the excess liquid refrigerant in the receiver 25 is exhausted, the enthalpy at the outlet of the heat source side heat exchanger 23 functioning as a condenser increases as shown at point M1 in FIG. 4, and the heat source side 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 supercooler 22 performs condensing and supercooling of the two-phase refrigerant, as shown at point N1. , The enthalpy at the outlet of the first supercooler 22 also increases.

[Comparison example]
Here, a comparative example to be compared with the present embodiment will be described. In the comparative example, the amount of the refrigerant is determined by using the degree of supercooling of the refrigerant. For example, when the amount of refrigerant is insufficient due to leakage of refrigerant or the like, the degree of supercooling decreases as shown in FIG. Therefore, in the comparative example, when the degree of supercooling becomes smaller than the preset threshold value, it is determined that the amount of the refrigerant is insufficient.

FIG. 5 is a diagram illustrating the relationship between the amount of refrigerant in the refrigerating apparatus shown in FIG. 1, the degree of supercooling of the first supercooler, and the operating conditions of the refrigerating apparatus. As shown in FIG. 5, the degree of supercooling of the first supercooler 22 varies greatly depending on the operating conditions of the refrigerating apparatus 1 (outside air temperature, heat exchange amount, refrigerant circulation amount, evaporation temperature, etc.). Therefore, when determining the insufficient amount of refrigerant by using the degree of supercooling as in the comparative example, it is necessary to set the supercooling degree threshold value S low so as not to cause 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 the insufficient amount of the refrigerant. For example, when the refrigerant leaks, the refrigerant The amount of leakage will increase.

[Judgment of refrigerant amount]
Therefore, in the present embodiment, the amount of the refrigerant is determined using the temperature efficiency ε of the first supercooler 22 whose fluctuation with respect to the change in the operating conditions of the refrigerating apparatus 1 is smaller than that of the degree of supercooling. The determination of the amount of refrigerant using temperature efficiency will be described below.

FIG. 6 shows 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 when the amount of the refrigerant is an appropriate amount in the refrigerating apparatus shown in FIG. It is a figure explaining. In FIG. 6, the vertical axis indicates the temperature, and the higher the temperature, the higher the temperature. The horizontal axis shows the refrigerant paths of the heat source side heat exchanger 23, the receiver 25, and the first supercooler 22. s1 is the condensation temperature of the refrigerant, s2 is the refrigerant temperature at the outlet of the first supercooler 22, and s3 is the outside air temperature.

The temperature efficiency ε of the first supercooler 22 indicates the efficiency of the first supercooler 22, and the maximum possible temperature difference A is taken as the denominator and the actual temperature difference B is taken as the numerator. .. In the first supercooler 22, the maximum possible temperature difference A is the difference between the refrigerant condensation temperature s1 and the outside air temperature s3, and the actually possible temperature difference B is the refrigerant condensation temperature s1 and the first supercooling. 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 for explaining the relationship between the amount of refrigerant in the refrigerating apparatus shown in FIG. 1, the temperature efficiency of the first supercooler, and the operating conditions of the refrigerating apparatus. In FIG. 7, the horizontal axis is the amount of refrigerant of the refrigerant, and the vertical axis is the temperature efficiency ε of the first supercooler 22. As shown in FIG. 7, when the amount of refrigerant becomes small, the amount of refrigerant becomes E, and the excess liquid refrigerant of the receiver 25 disappears, the temperature efficiency ε of the first supercooler 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 supercooler 22, and since the fluctuation due to the operating conditions of the refrigerating device 1 is smaller than the degree of supercooling, it becomes easy to set the threshold value of the refrigerating device 1. ..

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

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

ρh · Vh: High temperature side fluid density (kg / m ³ ) × high temperature side fluid volume flow rate (m ³ / h) is the refrigerant circulation amount G (kg / h), and the temperature efficiency increases as the refrigerant circulation amount G increases. descend. The amount of refrigerant circulation varies depending on the compressor frequency, the compressor suction gas pressure of the refrigerant, and the compressor suction gas temperature. Ch: The specific heat of the fluid on the high temperature side (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 peculiar to the refrigerating apparatus 1. ρm: Low temperature side fluid density (kg / m ³ ), Cm: Low temperature side fluid specific heat (KJ / kg) is the density and specific heat of air, but they are almost constant values.

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 refrigerating apparatus 1 are constant values. Further, the temperature efficiency varies depending on the amount of refrigerant circulation that fluctuates the heat passing rate (K), the high pressure that fluctuates the high temperature side fluid specific heat (Ch), and the air flow rate that fluctuates depending on the air volume of the heat source side fan 27. The amount of refrigerant circulation varies depending on the compressor frequency, the compressor intake gas pressure of the refrigerant, and the compressor intake gas temperature. Therefore, when the temperature efficiency threshold is changed and set 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. Set by.

[Change of threshold value depending on operating conditions]
When a refrigerant leaks, how much the refrigerant leaks can be judged as "the value of the temperature efficiency when the amount of the refrigerant is properly filled" and "the judgment threshold value εline of the temperature efficiency ε". It changes depending on the difference. That is, when the difference between the "value of the temperature efficiency when the amount of the refrigerant is properly filled" and the "determination threshold value εline of the temperature efficiency ε" is large, the refrigerant shortage cannot be determined unless a large amount of the refrigerant leaks. On the contrary, when the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is small, it is possible to judge the refrigerant shortage with a small amount of refrigerant leakage. ..

The temperature efficiency, which is an index for determining the refrigerant shortage, fluctuates less depending on the operating conditions than the supercooling value, but it fluctuates depending on the operating conditions as described above. Therefore, if the threshold value is changed according to the operating conditions, the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" can be reduced, and the amount of refrigerant is small. It is possible to determine the refrigerant shortage based on the amount of leakage. The threshold setting method according to the operating conditions will be described below.

[Threshold setting method 1 according to operating conditions]
As described above, the temperature efficiency fluctuates due to the fluctuation of the air flow rate. Therefore, in the present embodiment, the threshold value is changed according to the fan output% as the “threshold value setting method 1”. FIG. 8 is a diagram illustrating an example of the relationship between the temperature efficiency value of the refrigerating 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 value is set to decrease as the fan output decreases. As a result, under the condition of 40% fan air volume, the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is about 0.05 to 0.10. Become.

FIG. 14 is a diagram illustrating 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 “temperature efficiency value when the amount of refrigerant is properly filled” is 0.45, and the “threshold value” indicated by the broken line. Since the "temperature efficiency ε determination threshold value εline" 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, the "temperature efficiency value when the amount of refrigerant is properly filled" is 0.80, and the "temperature efficiency ε judgment threshold value εline" is 0. Since it is .40, 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 value setting method 1, the difference is 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. However, under the condition of 100% fan air volume, the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is about 0.20 to 0.30. Although 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, the difference is larger than the condition of the fan air volume of 40%.

[Threshold setting method 2 according to operating conditions]
As described above, the temperature efficiency fluctuates due to the fluctuation of the refrigerant circulation amount. Therefore, in the present embodiment, the threshold value is changed according to the amount of refrigerant circulating as the “threshold value setting method 2”. FIG. 9 is a diagram illustrating an example of the relationship between the temperature efficiency value of the refrigerating apparatus according to the embodiment of the present invention, the amount of circulating refrigerant on the high temperature side, and the amount of fan air. Specifically, as shown in FIG. 9, the threshold value of temperature efficiency is set to decrease as the amount of refrigerant circulation increases. As a result, under the condition that the fan air volume is 40%, the difference between the "temperature efficiency value when the amount of refrigerant is properly filled" and the "temperature efficiency ε judgment threshold value εline" is about 0.05 to 0.10. Therefore, as shown in FIG. 14, the "temperature efficiency value when the amount of refrigerant is properly filled" and the "temperature efficiency ε" are determined from the case where the "temperature efficiency ε determination threshold value εline" is a constant value. The difference in "threshold value εline" is improved. However, under the condition of 100% fan air volume, the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is about 0.20 to 0.30. Although 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, the difference is larger than the condition of the fan air volume of 40%.

Here, the amount of refrigerant circulation 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

Will be. Because the compressor suction refrigerant density is determined by the compressor suction pressure and the 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。

Will be. Here, f () represents a function whose parameter is the value in (). Therefore, the refrigerant density is calculated by the suction temperature sensor 33a and the suction pressure sensor 34a of the refrigerating device 1, and the refrigerant circulation amount is calculated by the compressor operating frequency and the constant 2. If there are multiple 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 carry out a complicated calculation with the controller. Therefore, although the accuracy is slightly reduced, the threshold value may be simply determined by 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 reduced, the threshold value may be determined simply by the total value of the compressor operating frequencies, or the threshold value may be changed only by the low pressure. Even in these cases, the "temperature efficiency value when the amount of refrigerant is properly filled" and the "temperature efficiency ε judgment threshold value" are higher than when 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 fluctuates due to the fluctuation of high pressure. Therefore, in the refrigerating apparatus 1, the threshold value is changed by the high pressure as the “threshold value setting method 3”. FIG. 10 is a diagram illustrating an example of the relationship between the temperature efficiency value of the refrigerating apparatus according to the embodiment of the present invention, the high pressure pressure, and the operating frequency. Specifically, as shown in FIG. 10, the threshold value of temperature efficiency is set to decrease as the high pressure pressure decreases. As a result, under the condition of a compressor operating frequency of 100 Hz, the difference between the "temperature efficiency value when the amount of refrigerant is properly filled" and the "temperature efficiency ε judgment threshold value εline" is about 0.05 to 0.10. 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 a compressor operating frequency of 30 Hz, the difference between the "value of temperature efficiency when the amount of refrigerant is properly filled" and the "determination threshold value εline of temperature efficiency ε" is about 0.20 to 0.30. The difference is improved as compared with the case where the “temperature efficiency ε determination threshold value εline” 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 mentioned above, the temperature efficiency fluctuates depending on both the air flow rate and the refrigerant circulation amount. Further, ΔT defined by the following (Formula 7) is also affected by both the air flow rate and the refrigerant circulation amount and fluctuates.

As the air volume decreases, the condenser outlet temperature increases, so ΔT also 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 that the temperature at the outlet of the condenser 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 value setting method 4 according to operating conditions”. FIG. 15 is a diagram illustrating an example of the relationship between the temperature efficiency value of the refrigerating apparatus according to the embodiment of the present invention and ΔT. Specifically, as shown in FIG. 15, the threshold value of temperature efficiency is set to decrease as ΔT increases. As a result, even if the fan output and operating frequency fluctuate, the difference between the "temperature efficiency value when the amount of refrigerant is properly filled" and the "temperature efficiency ε judgment threshold value εline" is 0.05 to 0. It becomes about 15, and the difference is significantly 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. In addition, the difference between "the value of temperature efficiency when the amount of refrigerant is properly filled" and "the judgment threshold value εline of temperature efficiency ε" is the largest compared to the threshold value setting methods 1 to 3 according to the operating conditions. Since it becomes smaller, the refrigerant shortage can be detected with the least appropriate amount of refrigerant leakage.

[Refrigerant amount determination operation]
FIG. 11 is a flowchart showing the procedure of the refrigerant amount 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 refrigerating device 1. The refrigerating apparatus 1 of the present embodiment determines the amount of refrigerant by using the temperature efficiency ε of the first supercooler 22. The determination of the amount of refrigerant described below can also be applied to the refrigerant filling work when installing the refrigerating device 1 or the refrigerant filling work when performing maintenance of the refrigerating device 1. Further, the refrigerant amount determination operation may be executed when receiving an instruction from a remote device (not shown).

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

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 refrigerating 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 the saturation temperature. For example, the heat source side control unit 31 raises the operating 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. Decrease 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 refrigerating apparatus 1 matches the target temperature (for example, 45 ° C.). Control the number of rotations of. 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 the saturation temperature. For example, the heat source side control unit 31 increases the rotation speed of the heat source side fan 27 when the current condensation temperature is higher than the target temperature, and increases the rotation speed of the heat source side fan 27 when the current condensation temperature is lower than the target temperature. Reduce the number of revolutions.

Further, for example, the heat source side control unit 31 adjusts the opening degree of the injection amount adjusting valve 72 of the first injection circuit 71 by using the signals obtained from the sensors. For example, the heat source side control unit 31 opens the injection amount adjusting valve 72 when the current discharge temperature of the compressor 21 is high, and the injection amount adjusting 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 user side fan 43 that blows air to the user side unit 4.

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

In step ST3, the heat source side control unit 31 acquires the operating state of the refrigerating device 1. The heat source side control unit 31 determines whether or not the current operating state corresponds to the exception condition for determining the amount of refrigerant. As an exception condition for determining the amount of the refrigerant, for example, the following conditions are set in advance. If any one of these is applicable, it is determined that the exception condition for determining the amount of refrigerant is applicable.
-When the compressor 21 is stopped.
・ 30 minutes after startup (because the 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 is also reduced, so there is a risk of false detection).
・ At high outside temperature, which is out of the operating range.
-When the temperature difference between the condensation temperature and the outside air temperature is large.
-When the temperature efficiency ε is a value that may fall below the threshold value due to the influence of the condensation temperature, the temperature difference between the condensation temperature and the outside air temperature, and the outside air temperature.
-When the super heat is small (because there is a possibility that the accumulator 24 has excess refrigerant even if the excess refrigerant in the liquid reservoir is exhausted, and there is no refrigerant leakage).
In the above cases, the value of the temperature efficiency ε becomes small and false detection occurs.

If the operating state of the refrigerating device 1 corresponds to the above-mentioned "exception condition for determining the amount of refrigerant", the process returns to step ST1, and the operating state of the refrigerating device 1 corresponds to the above-mentioned "exception condition for determining the amount of refrigerant". If not, the process proceeds to step ST4.

In step ST4, the heat source side control unit 31 determines whether the operation control of the refrigerating apparatus 1 started in step ST1 is being stably executed. FIG. 12 is a conceptual diagram illustrating the stability determination conditions in the embodiment of the present invention. The stability determination condition is set so that the plurality of temperature efficiencies ε calculated in step ST2 and the operating frequency at that time do not fluctuate significantly. 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) (white 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 amount of change from the average value of the target data exceeds a predetermined value (η) (black circle), it is determined that the stability determination condition is not satisfied. 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 in this way, the amount of the refrigerant can be determined more accurately.

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

In step ST5, the heat source side control unit 31 determines the suitability of the refrigerant amount by comparing the refrigerant amount determination parameter with the reference value thereof. Specifically, the deviation amount ΔT (= T−Tm) of the temperature efficiency ε of the first supercooler 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 amount of refrigerant 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 amount of refrigerant is insufficient, and proceeds to step ST7. At this time, it is desirable that the temperature efficiency ε of the first supercooler 22 takes a moving average of a plurality of temperature efficiencies ε different in time rather than using an instantaneous value. By taking a moving average of multiple temperature efficiencies ε that differ in time, the stability of the refrigeration cycle can also be considered. The determination threshold value Tm may be stored in advance in the storage unit 3c of the heat source side control unit 31 or may be set by input from a remote controller or a switch, and may be set from a remote device (not shown). It may be set according to the instruction of.

If the result of determining the amount of refrigerant in step ST5 is appropriate for the amount of refrigerant, the heat source side control unit 31 outputs in step ST6 that the amount of refrigerant is appropriate. When the amount of refrigerant is appropriate, the fact that the amount of refrigerant is appropriate is displayed on, for example, a display unit (not shown) such as an LED or a liquid crystal arranged in the refrigerating apparatus 1, or the amount of refrigerant is appropriate. A signal to that effect is transmitted to a remote device (not shown).

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

In the above embodiment, after the temperature efficiency ε is calculated in step ST2, it is determined in step ST3 whether or not the operating state of the refrigerating apparatus 1 corresponds to the exception condition, and in step ST4, the refrigerating apparatus It is determined whether or not the amount of the refrigerant is determined by determining whether or not the operation control of 1 is stable, but the present invention is not limited to this. Step ST2 may be executed after step ST3 and step ST4. By calculating the temperature efficiency ε after determining whether or not to determine the amount of the refrigerant, the amount of processing performed by the heat source side control unit 31 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 refrigerating apparatus 1 is short of refrigerant. Therefore, if the refrigerant leaks. However, the leakage of the refrigerant can be detected at an early stage.

Further, in the present embodiment, the operating state of the refrigerating device 1 is acquired, and the temperature efficiency threshold value for determining the refrigerant shortage using the temperature efficiency ε of the refrigerating device 1 is the operation of the refrigerating device 1. It changes according to the state. Therefore, it is possible to determine the amount of refrigerant shortage and leakage as small as possible, and the determination of refrigerant shortage is performed earlier than the conventional method. As a result, it is possible to reduce the rise in the temperature inside the refrigerator as much as possible, reduce the deterioration of the global environment, reduce the damage to the stored items due to the rise in the temperature inside the refrigerator when the refrigerant leaks, and reduce the recovery cost after the refrigerant leaks. In addition, since the temperature efficiency threshold value can be changed and judged with a small number of parameters, it is possible to make a judgment with as little refrigerant shortage and leakage as possible with simpler control.

In the operation control described above, the control for specifying the condensation temperature and the evaporation temperature is not performed, but 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 condensation temperature and the evaporation 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, control may be performed so that either the condensation temperature or the evaporation temperature becomes the target value. By controlling the operating state of the refrigerating device 1 to a certain condition, the fluctuation of the operating state amount that fluctuates according to the supercooling degree and the supercooling degree of the first supercooler 22 becomes small, and the threshold value can be determined. This makes it easier to determine that the amount of refrigerant is insufficient.

Further, by applying the refrigerant amount determination operation of the present embodiment to the refrigerant filling work at the initial stage of installation of the refrigerating device 1 or the refrigerant filling work when the refrigerant is once discharged and refilled at the time of maintenance, the refrigerant filling work is performed. It is possible to shorten the time and reduce the load on the operator.

[Modification example]
FIG. 13 is a diagram schematically showing a refrigerant circuit of a refrigerating apparatus according to a modified example of the present invention. Compared with the refrigerating device 1 shown in FIG. 1, the heat source side unit 2A of the refrigerating device 1A of the modified example has a second supercooler 26 instead of the first supercooler 22 as shown in FIG. are doing. The second supercooler 26 corresponds to the "supercooler" of the present invention. The second supercooler 26 includes, for example, a double-tube supercooler or a plate heat exchanger, and has a high-pressure refrigerant flowing through the heat source-side refrigerant circuit 10b and an intermediate pressure flowing through the first injection circuit 71A. It exchanges heat with the refrigerant of. A part of the refrigerant that has passed through the second supercooler 26 is expanded by the injection amount adjusting valve 72 to become an intermediate pressure refrigerant, and exchanges heat with the refrigerant that has passed through the second supercooler 26. Further, the intermediate pressure refrigerant flowing in from the injection amount adjusting valve 72 and exchanging heat in the second supercooler 26 becomes a refrigerant having a high degree of dryness, and the compressor 21 is used to lower the discharge temperature of the compressor 21. It is injected to the suction side. The refrigerant determination operation in the modified example is performed using the temperature efficiency of the second supercooler 26.

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

In the modified example, the first supercooler 22 may be added so that the refrigerant flowing out from the receiver 25 flows into the second supercooler 26 after passing through the first supercooler 22.

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

The second supercooler 26 of the modified example 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 transfer rate (W / (m ² · K)) fluctuates depending on the amount of refrigerant circulation. The temperature efficiency decreases as the amount of refrigerant circulation 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. As the amount of circulating refrigerant Gm increases, the temperature efficiency decreases. The amount of refrigerant circulation Gm flowing through the first injection circuit 71A varies depending on the opening degree of the injection amount adjusting valve 72 and the differential pressures upstream and downstream of the injection amount adjusting valve 72.

Cm: The specific heat of the fluid on the low temperature side (KJ / kg) fluctuates depending on 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 supercooler 22 of the embodiment.

From the above, A (heat transfer area) is a constant value peculiar to the refrigerating apparatus 1A. The temperature efficiency varies depending on the high-temperature side refrigerant circulation amount that fluctuates the heat passing rate (K), the low-temperature side refrigerant circulation amount that flows through the first injection circuit 71A, the high-pressure pressure that fluctuates the high-temperature side fluid specific heat (Ch), and the intermediate pressure. To do. Therefore, when the threshold value of the temperature efficiency is changed and set according to the operating conditions, it is set according to the high temperature side refrigerant circulation amount, the low temperature side refrigerant circulation amount, the high pressure pressure, and the intermediate pressure. The amount of circulating refrigerant on the high temperature side varies depending on the compressor frequency, the compressor intake gas pressure of the refrigerant, and the compressor intake gas temperature. Further, 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 injection amount adjusting valve 72 upstream and downstream.

Also in the modified example, 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 according to operating conditions] and [threshold setting method 3 according to operating conditions] are used, respectively. Can be done.

[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 amount. Therefore, in the present embodiment, the threshold value is changed according to the low temperature side refrigerant circulation amount as the “threshold value setting method 5 according to the operating conditions”. Specifically, as in FIG. 9, the threshold value of the temperature efficiency is set to decrease as the circulation amount of the refrigerant on the low temperature side increases. As a result, 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 refrigerating apparatus 1 is an electronic expansion valve, the value that outputs the opening degree of the injection amount adjusting valve 72 by the control unit 3, 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 the 71A downstream of the injection amount adjusting valve 72 does not have a pressure sensor, it 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 carry out a complicated calculation with the controller. Therefore, although the accuracy is slightly reduced, either the value that 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, or the pressure upstream of the injection amount adjusting valve 72 is used. The threshold value may be determined by using one or more of the parameters of the above.

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

Further, the threshold value may be changed by using 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 by using the density upstream of the injection amount adjusting valve 72 as a parameter.

Further, the opening degree of the injection amount adjusting valve 72 described above, 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 by using any one of the temperatures upstream of the regulating valve 72 as a parameter, or the threshold value may be changed by using a plurality of these as parameters.

The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. That is, the configuration of the above embodiment may be appropriately improved, or at least a part thereof may be replaced with another configuration. Further, the configuration requirements without particular limitation on 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.

1 Refrigeration unit, 1A refrigeration equipment, 2 heat source side unit, 2A heat source side unit, 3 control unit, 3a acquisition unit, 3b calculation unit, 3c storage unit, 3d drive unit, 3e input unit, 3f output unit, 4 user side unit 5, Overcooling heat exchanger, 6-liquid refrigerant extension pipe, 7 Gas refrigerant extension pipe, 10 Refrigerator circuit, 10a User side refrigerant circuit, 10b Heat source side refrigerant circuit, 21 Compressor, 22 First supercooler, 23 Heat source side Heat exchanger, 24 accumulator, 25 receiver, 26 second supercooler, 27 heat source side fan, 28 liquid side closing valve, 29 gas side closing valve, 31 heat source side control unit, 32 user 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 User side heat exchange inlet temperature sensor, 33f User side heat exchange outlet temperature sensor, 33g Suction air temperature sensor, 34a Suction pressure sensor , 34b Discharge pressure sensor, 41 Utilization side expansion valve, 42 Utilization side heat exchanger, 43 Utilization side fan, 71 1st injection circuit, 71A 1st injection circuit, 72 Injection amount adjustment valve, 73 2nd injection circuit, 74 Capillary Tube, 75 Electromagnetic valve for suction injection, T temperature efficiency, T1 temperature efficiency threshold, T2 temperature efficiency threshold, T3 temperature efficiency threshold.

Claims (9)

A compressor, a heat source side heat exchanger, a heat source side unit having a heat source side fan for blowing air to the heat source side heat exchanger, and a supercooler, a user side expansion valve, and a user side heat exchanger. A refrigerating apparatus having a refrigerant circuit in which at least one user-side unit is connected by a pipe to circulate the refrigerant.
A refrigerant shortage determination unit that determines the shortage of the amount of refrigerant filled in the refrigerant circuit using the temperature efficiency of the supercooler, and a refrigerant shortage determination unit.
An injection tube that branches from the downstream of the heat source side heat exchanger and is connected to the intermediate pressure port of the compressor or the suction side of the compressor.
The injection amount adjusting valve provided in the injection pipe is provided.
The supercooler is configured to exchange heat between the refrigerant flowing out of the heat source side heat exchanger and the refrigerant expanded by the injection amount adjusting valve.
The refrigerant shortage determination unit determines that the amount of refrigerant is insufficient by comparing the temperature efficiency of the supercooler with the temperature efficiency threshold value that is changed according to the operating state of the refrigerating apparatus, and operates the refrigerating apparatus. The temperature efficiency threshold is changed based on the state.
The refrigerant shortage determination unit includes the opening degree of the injection amount adjusting valve, the differential pressure between the upstream and downstream of the injection amount adjusting valve, the density upstream of the injection amount adjusting valve, and the pressure upstream of the injection amount adjusting valve. A refrigerating device that changes the temperature efficiency threshold value using any one or more of the temperatures upstream of the injection amount adjusting valve as a parameter. The refrigerating apparatus according to claim 1, wherein the refrigerant shortage determination unit changes the temperature efficiency threshold value based on the maximum temperature difference between the high temperature side fluid and the low temperature side fluid whose heat is exchanged by the supercooler. The refrigerant shortage determination unit, based on at least one of the suction pressure of the frequency of the compressor and the compressor, the refrigeration apparatus according to claim 1 for changing the temperature efficiency threshold. The refrigerating device according to any one of claims 1 to 3, wherein the temperature efficiency threshold value changed by the refrigerant shortage determination unit is set by an instruction from a remote controller, a switch, or a remote device. A control unit that controls the operating frequency of the compressor and the rotation speed of the fan on the heat source side to be constant is provided.
The refrigerating apparatus according to any one of claims 1 to 4, wherein the refrigerant shortage determination unit determines the insufficient amount of the refrigerant during its control. A control unit for controlling either the condensation temperature or the evaporation temperature of the heat source side heat exchanger to be a target value is provided.
The refrigerating apparatus according to any one of claims 1 to 4, wherein the refrigerant shortage determination unit determines the insufficient amount of the refrigerant during its control. The one according to any one of claims 1 to 6, wherein the refrigerant shortage determination unit slightly changes the temperature efficiency threshold value when the circulation amount of the refrigerant, which is the high temperature side fluid heat exchanged by the supercooler, increases. Refrigerator. The refrigerant shortage determination unit determines the temperature efficiency based on the frequency of the compressor used for calculating the circulation amount of the refrigerant which is the high temperature side fluid heat exchanged by the supercooler or the suction density of the compressor. The refrigerating apparatus according to any one of claims 1 to 7, wherein the value is changed. The refrigerant shortage determination unit changes the temperature efficiency threshold value based on the suction pressure of the compressor or the suction temperature of the compressor used for calculating the suction density of the compressor according to claims 1 to 8. The refrigerating apparatus according to any one item.

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