WO2017057711A1

WO2017057711A1 - Refrigeration apparatus

Info

Publication number: WO2017057711A1
Application number: PCT/JP2016/079090
Authority: WO
Inventors: 東近藤; 貴仁中山
Original assignee: ダイキン工業株式会社
Priority date: 2015-09-30
Filing date: 2016-09-30
Publication date: 2017-04-06
Also published as: JP2017067435A; JP6075500B1

Abstract

In the present invention, a control unit (8) is configured to control the degree of opening of an expansion mechanism (51) during a refrigeration-cycle operation, and performs expansion mechanism suitability determination as to whether the suitable expansion mechanism (51) is provided in a refrigerant circuit (10) on the basis of a first determination condition concerning the state quantity of a refrigerant, a compressor (21) and/or the expansion mechanism (51) when the degree of opening of the expansion mechanism (51) varies, and/or a second determination condition concerning the state quantity of the refrigerant, the compressor (21) and/or the expansion mechanism (51) when the degree of opening of the expansion mechanism (51) does not vary.

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus, in particular, a compressor circuit, a radiator, an expansion mechanism including an electric expansion valve, and an evaporator, and a refrigerant circuit configured by being connected to the refrigerant circuit. And a control unit that performs a refrigeration cycle operation in which a compressor, a radiator, an expansion mechanism, and an evaporator are circulated in this order.

Conventionally, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2011-252623), a compressor, an external heat exchanger (radiator), an internal expansion valve (expansion mechanism) including an electric expansion valve, There is a refrigeration apparatus including a refrigerant circuit configured by connecting an internal heat exchanger (evaporator). The compressor and the external heat exchanger are provided in the external unit (heat source unit), and the internal expansion valve and the internal heat exchanger are provided in the internal unit (usage unit). The refrigeration apparatus is configured by connecting the internal unit to the external unit.

In the above refrigeration apparatus, the refrigeration apparatus may be updated by exchanging the heat source unit while diverting the existing use unit. When the refrigeration apparatus is updated, the refrigerant may be changed to a different one from that used in the refrigerant circuit of the existing refrigeration apparatus. In this case, since a refrigerant different from the refrigerant before renewal flows to the existing use unit, the existing expansion mechanism cannot be diverted as it is depending on the difference in physical properties of the refrigerant before and after renewal, It is necessary to select and replace an expansion mechanism suitable for the renewed refrigerant.

However, when renewing the refrigeration system including such replacement of the expansion mechanism, there is a possibility that an expansion mechanism selection error or forgetting replacement may occur. Therefore, in the updated refrigeration system, there is an appropriate expansion mechanism in the refrigerant circuit. It is desirable to be able to determine whether it is provided.

An object of the present invention is to provide a refrigerant circuit configured by connecting a compressor, a radiator, an expansion mechanism including an electric expansion valve, and an evaporator, and a refrigerant filled in the refrigerant circuit. And a control unit that performs a refrigeration cycle operation in which a radiator, an expansion mechanism, and an evaporator are circulated in this order, and to determine whether an appropriate expansion mechanism is provided in the refrigerant circuit. .

A refrigeration apparatus according to a first aspect is filled with a refrigerant circuit configured by connecting a compressor, a radiator, an expansion mechanism including an electric expansion valve, and an evaporator, and the refrigerant circuit. A control unit that performs a refrigeration cycle operation in which the refrigerant is circulated in the order of a compressor, a radiator, an expansion mechanism, and an evaporator. Here, the control unit is configured to control the opening degree of the expansion mechanism during the refrigeration cycle operation, and the refrigerant, the compressor, and / or the expansion mechanism when the opening degree of the expansion mechanism varies. Based on the first determination condition regarding the state quantity and / or the second determination condition regarding the state quantity of the refrigerant, the compressor and / or the expansion mechanism when the opening degree of the expansion mechanism is not fluctuating, it is appropriate for the refrigerant circuit. Whether or not the expansion mechanism is provided is determined.

Here, it is determined whether or not the operation state is in an unstable state quantity despite the fact that the opening degree of the expansion mechanism that is controlling the opening degree fluctuates according to the first determination condition. Further, it is determined whether or not the second determination condition is in an operating state indicating an abnormal state quantity even though the opening degree of the expansion mechanism performing the opening degree control is not fluctuating. In this case, it is assumed that an operation state that satisfies the first determination condition and the second determination condition occurs due to the fact that an appropriate expansion mechanism is not provided in the refrigerant circuit.

As described above, the first determination condition or the second determination condition based on the state quantity that appears in accordance with the operation state of the expansion mechanism performing the opening degree control (the presence or absence of opening degree fluctuation) is appropriate for the refrigerant circuit. Whether or not the expansion mechanism is provided can be determined.

In the refrigeration apparatus according to the second aspect, in the refrigeration apparatus according to the first aspect, the control unit determines whether the valve diameter of the expansion mechanism is larger than the valve diameter appropriate for the refrigerant circuit based on the first determination condition. Based on the second determination condition, it is determined whether the valve diameter of the expansion mechanism is smaller than the valve diameter appropriate for the refrigerant circuit.

If an expansion mechanism with a valve diameter larger than the appropriate valve diameter is provided in the refrigerant circuit, the expansion mechanism is often controlled in a smaller opening range. Regardless, the state quantity may be difficult to stabilize. In addition, if an expansion mechanism having a valve diameter smaller than the appropriate valve diameter is provided in the refrigerant circuit, the opening degree of the expansion mechanism is often controlled in a larger opening range. In spite of doing, it may show an abnormal amount of state.

Therefore, here, as described above, when the first determination condition is satisfied, it is determined that the valve diameter of the expansion mechanism is larger than the valve diameter appropriate for the refrigerant circuit, and when the second determination condition is satisfied. Determines that the valve diameter of the expansion mechanism is smaller than the valve diameter appropriate for the refrigerant circuit.

Thereby, here, in the refrigeration cycle operation after the renewal of the refrigeration apparatus including replacement of the expansion mechanism, it is determined whether the first determination condition or the second determination condition is satisfied. You can discover whether forgetfulness has occurred.

In the refrigeration apparatus according to the third aspect, in the refrigeration apparatus according to the first or second aspect, the control unit is based on an evaporator outlet superheat degree that is a superheat degree of the refrigerant at the evaporator outlet during the refrigeration cycle operation. The opening degree of the expansion mechanism is controlled. Here, the control unit determines whether or not the first determination condition is satisfied based on whether or not the fluctuation range of the evaporator outlet superheat degree exceeds the superheat degree fluctuation determination value.

In the case of controlling the opening degree of the expansion mechanism based on the degree of superheat of the evaporator outlet, if the appropriate expansion mechanism is provided in the refrigerant circuit, the degree of superheat of the evaporator outlet is stabilized by the degree of opening control of the expansion mechanism. The fluctuation range of the degree of superheat at the outlet is kept small. On the other hand, if an appropriate expansion mechanism is not provided in the refrigerant circuit as in the case where an expansion mechanism having a valve diameter larger than the appropriate valve diameter is provided in the refrigerant circuit, the opening degree of the expansion mechanism is controlled. The evaporator outlet superheat degree is not stable, and the fluctuation range of the evaporator outlet superheat degree becomes large.

Therefore, here, as described above, when the fluctuation range of the evaporator superheat degree exceeds the superheat degree fluctuation determination value, the fluctuation of the evaporator superheat degree is large with respect to the opening degree fluctuation of the expansion mechanism. It is determined that the opening control of the expansion mechanism is being performed, that is, it is determined that the first determination condition is satisfied.

Thus, here, the evaporator outlet superheat degree is used as a state quantity serving as an index as to whether or not the first determination condition is satisfied, and is based on the degree of stability of the evaporator outlet superheat degree by the opening degree control of the expansion mechanism. Thus, it can be determined whether or not an appropriate expansion mechanism is provided in the refrigerant circuit.

In the refrigeration apparatus according to the fourth aspect, in the refrigeration apparatus according to any one of the first to third aspects, the controller controls the capacity of the compressor based on the low pressure in the refrigeration cycle operation during the refrigeration cycle operation. Is going. In this case, the control unit determines whether or not the first determination condition is satisfied based on whether or not the fluctuation range of the low pressure exceeds the low pressure fluctuation determination value.

In the case of controlling the capacity of the compressor based on the low pressure in the refrigeration cycle operation, if an appropriate expansion mechanism is provided in the refrigerant circuit, even if the low pressure changes due to the opening control of the expansion mechanism, The fluctuation range is small. On the other hand, if an appropriate expansion mechanism is not provided in the refrigerant circuit as in the case where an expansion mechanism having a valve diameter larger than the appropriate valve diameter is provided in the refrigerant circuit, the pressure is reduced along with the opening degree control of the expansion mechanism. When the pressure fluctuates, the fluctuation range becomes large.

Thus, here, as described above, when the fluctuation range of the low pressure exceeds the low pressure fluctuation determination value, the opening degree control of the expansion mechanism is performed in a state where the fluctuation of the low pressure pressure is larger than the fluctuation of the opening degree of the expansion mechanism. It is determined that it is performed, that is, it is determined that the first determination condition is satisfied.

Thus, in this case, the low-pressure pressure is used as the state quantity serving as an index as to whether or not the first determination condition is satisfied, and the refrigerant circuit is based on the degree of stability of the low-pressure pressure accompanying the opening degree control of the expansion mechanism. It can be determined whether an appropriate inflation mechanism is provided.

A refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to any one of the first to fourth aspects, wherein the control unit is configured so that the low-pressure pressure in the refrigeration cycle operation becomes a target low pressure during the refrigeration cycle operation. The capacity is controlled. And here, the control unit is based on whether the expansion mechanism reaches the maximum opening and the low pressure is lower than the target low pressure, or the expansion mechanism reaches the maximum opening, and the compressor It is determined whether the second determination condition is satisfied based on whether the capacity has reached the minimum capacity.

When the capacity control of the compressor is performed so that the low pressure in the refrigeration cycle operation becomes the target low pressure, if the appropriate expansion mechanism is provided in the refrigerant circuit, the expansion mechanism reaches the maximum opening and the refrigerant circulation Despite the situation where the flow rate is likely to increase, the low-pressure pressure does not become so low that it does not reach the target low-pressure, and the compressor capacity does not decrease to the minimum capacity. It can be said that the range of control is wide. On the other hand, if an appropriate expansion mechanism is not provided in the refrigerant circuit as in the case where an expansion mechanism having a valve diameter smaller than the appropriate valve diameter is provided in the refrigerant circuit, the expansion mechanism reaches the maximum opening. Despite the situation where the circulating flow rate of the refrigerant is likely to increase, the low-pressure pressure may become lower than the target low-pressure, and the compressor capacity may become the minimum capacity. It can be said that the range of opening control of the mechanism is narrow.

Therefore, here, as described above, when the expansion mechanism reaches the maximum opening and the low pressure is lower than the target low pressure, or the expansion mechanism reaches the maximum opening and the capacity of the compressor is minimum. When the capacity has been reached, the range of the opening control of the expansion mechanism is too narrow in performing the capacity control of the compressor so that the low pressure becomes the target low pressure, that is, the second determination condition is satisfied. Judgment is made.

Thus, here, the low pressure or the capacity of the compressor is used as a state quantity that serves as an index as to whether or not the second determination condition is satisfied, and the low pressure or the compression when the expansion mechanism reaches the maximum opening degree. Based on the capacity of the machine, it can be determined whether an appropriate expansion mechanism is provided in the refrigerant circuit.

A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to any one of the first to fifth aspects, wherein the refrigerant circuit further includes a second expansion mechanism between the radiator and the expansion mechanism. As the refrigeration cycle operation, the control unit performs an operation of circulating the refrigerant filled in the refrigerant circuit in the order of the compressor, the radiator, the second expansion mechanism, the expansion mechanism, and the evaporator. And a control part performs control which makes the opening degree of a 2nd expansion mechanism small, when it determines with satisfy | filling 1st determination conditions.

When it is determined that the state quantity is in an unstable operating state despite the fact that the opening degree of the expansion mechanism performing opening degree control is fluctuating according to the first determination condition It is preferable to improve the operation state and stabilize the refrigeration cycle operation.

Therefore, here, as described above, when it is determined that the first determination condition is satisfied, control is performed to reduce the opening degree of the second expansion mechanism provided between the radiator and the expansion mechanism. I am doing so.

This makes it possible to control the expansion mechanism in a larger opening range, and to improve the operation state in which the state quantity is not stabilized only by controlling the opening of the expansion mechanism.

It is a schematic block diagram of the freezing apparatus concerning one Embodiment of this invention. It is a control block diagram of a freezing apparatus. It is a flowchart which shows an expansion mechanism suitability determination process. It is a figure which shows the time-dependent change of the low pressure or the evaporator outlet superheat degree at the time of cooling operation. It is a flowchart which shows the expansion mechanism suitability determination process in a modification.

Hereinafter, an embodiment of a refrigeration apparatus according to the present invention will be described with reference to the drawings. In addition, the specific structure of embodiment of the freezing apparatus concerning this invention is not restricted to the following embodiment and its modification, It can change in the range which does not deviate from the summary of invention.

(1) Configuration of Refrigeration Device FIG. 1 is a schematic configuration diagram of a refrigeration device 1 according to an embodiment of the present invention. The refrigeration apparatus 1 is an apparatus that cools a use-side space such as in a refrigerated warehouse or a showcase of a store by a vapor compression refrigeration cycle. The refrigeration apparatus 1 mainly includes a heat source unit 2, a utilization unit 5, and a liquid refrigerant communication tube 6 and a gas refrigerant communication tube 7 that connect the heat source unit 2 and the utilization unit 5. The vapor compression refrigerant circuit 10 of the refrigeration apparatus 1 is configured by connecting the heat source unit 2 and the utilization unit 5 via a liquid refrigerant communication tube 6 and a gas refrigerant communication tube 7. Here, the refrigeration apparatus 1 is updated by replacing the existing heat source unit with the new heat source unit 2 while diverting the existing use unit 5. In addition, when the refrigerating apparatus 1 is updated, the refrigerant is also changed to a different one (for example, R410A or R32) from that used in the refrigerant circuit of the existing refrigerating apparatus (for example, R22 or R407C).

<Usage unit>
As described above, the utilization unit 5 is connected to the heat source unit 2 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 and constitutes a part of the refrigerant circuit 10.

Next, the configuration of the usage unit 5 will be described.

The utilization unit 5 mainly includes a utilization side expansion valve 51 (expansion mechanism) and a utilization side heat exchanger 52 (evaporator). The usage unit 5 includes a usage-side liquid refrigerant tube 53 that connects the liquid-side end of the usage-side heat exchanger 52 and the liquid refrigerant communication tube 6, and a gas-side end of the usage-side heat exchanger 52 and a gas refrigerant communication tube. And a use-side gas refrigerant pipe 54 connected to the terminal 7.

The use side expansion valve 51 is an electric expansion valve capable of opening degree control, and is provided in the use side liquid refrigerant pipe 53.

The use side heat exchanger 52 is a heat exchanger that functions as a low-pressure refrigerant evaporator in the refrigeration cycle and cools the internal air (use side air). Here, the usage unit 5 has a usage-side fan 55 for sucking usage-side air into the usage unit 5 and exchanging heat with the refrigerant in the usage-side heat exchanger 52 and then supplying it to the usage-side space. is doing. That is, the usage unit 5 includes the usage-side fan 55 as a fan that supplies usage-side air as a heating source of the refrigerant flowing through the usage-side heat exchanger 52 to the usage-side heat exchanger 52. The use side fan 55 is rotationally driven by a use side fan motor 56.

The use unit 5 is provided with various sensors. Specifically, an evaporator outlet temperature sensor 57 that detects an evaporator outlet temperature Tg that is a refrigerant temperature at the gas side end (evaporator outlet) of the usage side heat exchanger 52 is provided in the usage side gas refrigerant pipe 54. Is provided. Further, a usage-side air temperature sensor 58 that detects a temperature Tr of usage-side air sucked into the usage unit 5 is provided around the usage-side heat exchanger 52 or the usage-side fan 55.

The usage unit 5 includes a usage-side control unit 50 that controls the operation of each unit constituting the usage unit 5. The use-side control unit 50 includes a microcomputer, a memory, and the like provided to control the use unit 5 so that control signals and the like can be exchanged with the heat source unit 2. It has become.

<Heat source unit>
As described above, the heat source unit 2 is connected to the utilization unit 5 via the liquid refrigerant communication tube 6 and the gas refrigerant communication tube 7 and constitutes a part of the refrigerant circuit 10.

Next, the configuration of the heat source unit 2 will be described.

The heat source unit 2 mainly includes a compressor 21, a heat source side heat exchanger 23 (heat radiator), a receiver 24, a supercooler 25, an injection pipe 26, a heat source side expansion valve 28, and a liquid side closing valve. 29 and a gas side closing valve 30. The heat source unit 2 includes a first heat source side gas refrigerant pipe 31 that connects the discharge side of the compressor 21 and the gas side end of the heat source side heat exchanger 23, and the liquid side end and liquid of the heat source side heat exchanger 23. A heat source side liquid refrigerant pipe 32 connecting the refrigerant communication pipe 6 and a second heat source side gas refrigerant pipe 33 connecting the suction side of the compressor 21 and the gas refrigerant communication pipe 7 are provided.

The compressor 21 is a device that compresses the low-pressure refrigerant in the refrigeration cycle until it reaches a high pressure. Here, as the compressor 21, a compressor having a hermetic structure in which a rotary type or scroll type positive displacement compression element (not shown) is rotationally driven by a compressor motor 22 is used. Further, here, the compressor motor 22 can control the operating frequency Fc by an inverter, whereby the capacity control of the compressor 21 can be performed.

The heat source side heat exchanger 23 is a heat exchanger that functions as a high-pressure refrigerant radiator in the refrigeration cycle. Here, the heat source unit 2 sucks outside air (heat source side air) into the heat source unit 2, exchanges heat with the refrigerant in the heat source side heat exchanger 23, and then discharges the heat source side fan to the outside. 34. That is, the heat source unit 2 has a heat source side fan 34 as a fan that supplies heat source side air as a cooling source of the refrigerant flowing through the heat source side heat exchanger 23 to the heat source side heat exchanger 23. The heat source side fan 34 is rotationally driven by a heat source side fan motor 35.

The receiver 24 is a container that temporarily accumulates the refrigerant condensed in the heat source side heat exchanger 23 as a radiator, and is provided in the heat source side liquid refrigerant pipe 32.

The subcooler 25 is a heat exchanger that further cools the refrigerant temporarily stored in the receiver 24, and is provided in the downstream portion of the receiver 24 of the heat source side liquid refrigerant pipe 32.

The injection pipe 26 is a refrigerant pipe that branches a part of the refrigerant flowing through the heat source side liquid refrigerant pipe 32 and returns it to the compressor 21. Here, a part of the heat source side liquid refrigerant pipe 32 on the downstream side of the subcooler 25. It is provided so that it may branch from and may be returned in the middle of the compression stroke of the compressor 21. The injection pipe 26 is provided so as to pass through the subcooler 25 while being branched from the heat source side liquid refrigerant pipe 32 and returning to the compressor 21. An injection valve 27 is provided in a portion of the injection pipe 26 up to the inlet of the supercooler 25. The injection valve 27 is an electric expansion valve whose opening degree can be controlled, and the pressure is reduced before the refrigerant flowing through the injection pipe 26 flows into the subcooler 25. As described above, the subcooler 25 cools the refrigerant temporarily stored in the receiver 24 using the refrigerant branched from the heat source side liquid refrigerant pipe 32 through the injection pipe 26 as a cooling source.

The heat source side expansion valve 28 is an electric expansion valve whose opening degree can be controlled, and is provided in a portion of the heat source side liquid refrigerant pipe 32 on the downstream side of the subcooler 25.

The liquid side closing valve 29 is a manual valve provided at a connection portion of the heat source side liquid refrigerant pipe 32 with the liquid refrigerant communication pipe 6.

The gas side shut-off valve 30 is a manual valve provided at a connection portion of the second heat source side liquid refrigerant pipe 33 with the gas refrigerant communication pipe 7.

The heat source unit 2 is provided with various sensors. Specifically, in the vicinity of the compressor 21 of the heat source unit 2, a suction pressure sensor 36 that detects a suction pressure LP that is a refrigerant pressure on the suction side of the compressor 21, and a refrigerant pressure on the discharge side of the compressor 21. And a discharge pressure sensor 37 for detecting the discharge pressure HP.

The heat source unit 2 has a heat source side control unit 20 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 20 includes a microcomputer and a memory provided for controlling the heat source unit 2, and exchanges control signals and the like with the use side control unit 50 of the use unit 5. Can be done. That is, the control part 8 which performs operation control of the whole refrigerating apparatus 1 is comprised by connecting the utilization side control part 50 and the heat source side control part 20 so that communication is possible.

As shown in FIG. 2, the control unit 8 is connected so as to receive detection signals from

various sensors

36, 37, 57, and 58, and

various devices

21 and 27 based on these detection signals and the like. , 34, 51, etc. are connected so that they can be controlled. Here, FIG. 2 is a control block diagram of the refrigeration apparatus 1.

Thus, the refrigerant circuit 10 of the refrigeration apparatus 1 mainly includes the compressor 21, the heat source side heat exchanger 23 (heat radiator), the use side expansion valve 51 (expansion mechanism) including an electric expansion valve, and the use side. It is comprised by connecting with the heat exchanger 52 (evaporator). And the control part 8 of the freezing apparatus 1 uses the refrigerant | coolant with which the refrigerant circuit 10 was filled for the compressor 21, the heat-source side heat exchanger 23 (radiator), the utilization side expansion valve 51 (expansion mechanism), and a utilization side heat exchanger. The cooling operation (refrigeration cycle operation) is performed in the order of 52 (evaporator).

(2) Basic operation of the refrigeration apparatus Next, the basic operation and control of the refrigeration apparatus 1 will be described with reference to FIGS. 1 and 2.

As a basic operation of the refrigeration apparatus 1, the refrigerant filled in the refrigerant circuit 10 is mainly composed of a compressor 21, a heat source side heat exchanger 23 (radiator), a receiver 24, a subcooler 25, a heat source side expansion valve 28, A cooling operation (refrigeration cycle operation) is circulated in the order of the use side expansion valve 51 (expansion mechanism) and the use side heat exchanger 52 (evaporator). In this cooling operation, a part of the refrigerant flowing through the heat source side liquid refrigerant pipe 32 is branched through the injection pipe 26, passes through the subcooler 25, and then returned to the compressor 21. Note that the cooling operation and control as the basic operation of the refrigeration apparatus 1 described below are performed by the control unit 8 that controls the components of the refrigeration apparatus 1.

The refrigerant filled in the refrigerant circuit 10 is first sucked into the compressor 21 and compressed from the low pressure to the high pressure in the refrigeration cycle and then discharged. Here, the low pressure in the refrigeration cycle is the suction pressure LP detected by the suction pressure sensor 36. Further, the compressor 21 is controlled in capacity according to the cooling load required by the utilization unit 5. Specifically, the cooling load required by the utilization unit 5 is obtained based on the temperature difference ΔTr (= Tr−Trt) between the temperature Tr of the utilization side air and the target value Trt. Then, the target value LPt of the low pressure LP in the refrigeration cycle is set according to the cooling load required by the use unit 5, and the operating frequency of the compressor 21 is set so that the low pressure LP in the refrigeration cycle becomes the target low pressure LPt. Fc is controlled. The gas refrigerant discharged from the compressor 21 flows into the gas side end of the heat source side heat exchanger 23 through the first heat source side gas refrigerant pipe 31.

The gas refrigerant that has flowed into the gas side end of the heat source side heat exchanger 23 performs heat exchange with the heat source side air supplied by the heat source side fan 34 in the heat source side heat exchanger 23 to dissipate and condense, and is supercooled. It becomes a liquid refrigerant in a state and flows out from the liquid side end of the heat source side heat exchanger 23.

The liquid refrigerant flowing out from the liquid side end of the heat source side heat exchanger 23 flows into the inlet of the receiver 24 through a portion between the heat source side heat exchanger 23 and the receiver 24 of the heat source side liquid refrigerant pipe 32.

The liquid refrigerant that has flowed into the receiver 24 is temporarily stored as a saturated liquid refrigerant in the receiver 24, and then flows out from the outlet of the receiver 24.

The liquid refrigerant flowing out from the outlet of the receiver 24 flows into the inlet of the subcooler 25 on the heat source side liquid refrigerant tube 32 side through the portion between the receiver 24 and the subcooler 25 of the heat source side liquid refrigerant tube 32.

The liquid refrigerant flowing into the subcooler 25 exchanges heat with the refrigerant flowing through the injection pipe 26 in the subcooler 25 and is further cooled to become a supercooled liquid refrigerant. It flows out from the outlet on the refrigerant pipe 32 side. At this time, a part of the refrigerant flowing through the heat source side liquid refrigerant pipe 32 is branched to the injection pipe 26 and is reduced by the injection valve 27 until it reaches an intermediate pressure in the refrigeration cycle. The refrigerant flowing through the injection pipe 26 after being decompressed by the injection valve 27 flows into the inlet of the subcooler 25 on the injection pipe 26 side. The refrigerant flowing into the inlet of the subcooler 25 on the injection pipe 26 side is heated in the supercooler 25 by exchanging heat with the refrigerant flowing through the heat source side liquid refrigerant pipe 32 to become a gas refrigerant. Then, the refrigerant heated in the subcooler 25 flows out from the outlet of the subcooler 25 on the injection pipe 26 side, and is returned to the middle of the compression stroke of the compressor 21.

The liquid refrigerant flowing out from the outlet on the heat source side liquid refrigerant tube 32 side of the subcooler 25 passes through the portion between the subcooler 25 and the heat source side expansion valve 28 of the heat source side liquid refrigerant tube 32, and then the heat source side expansion valve 28. Flow into. At this time, a part of the liquid refrigerant flowing out from the outlet of the subcooler 25 on the heat source side liquid refrigerant pipe 32 side is from a portion between the subcooler 25 of the heat source side liquid refrigerant pipe 32 and the heat source side expansion valve 28. The injection pipe 26 is branched.

The liquid refrigerant that has flowed into the heat source side expansion valve 28 is decompressed by the heat source side expansion valve 28, and then passes through the liquid side closing valve 29, the liquid refrigerant communication pipe 6, and a part of the use side liquid refrigerant pipe 53. 51 flows in.

The refrigerant that has flowed into the use-side expansion valve 51 is decompressed by the use-side expansion valve 51 until it reaches a low pressure in the refrigeration cycle, and between the use-side expansion valve 51 and the use-side heat exchanger 52 in the use-side liquid refrigerant pipe 53. It flows into the liquid side end of the use side heat exchanger 52 through this part.

The refrigerant flowing into the liquid side end of the usage-side heat exchanger 52 evaporates by exchanging heat with the usage-side air supplied by the usage-side fan 55 in the usage-side heat exchanger 52 to become a gas refrigerant. It flows out from the gas side end (evaporator outlet) of the side heat exchanger 52. Here, the superheat degree of the refrigerant at the outlet of the use side heat exchanger 52 is the evaporator outlet superheat degree SH, and the opening degree control of the use side expansion valve 51 is performed based on the evaporator outlet superheat degree SH. It is like that. Specifically, it is obtained by converting the low pressure LP to its equivalent saturation temperature Te (= evaporation temperature) and subtracting this equivalent saturation temperature Te from the evaporator outlet temperature Tg. And the opening degree of the use side expansion valve 51 is controlled so that the evaporator outlet superheat degree SH becomes the target superheat degree SHt.

The gas refrigerant flowing out from the gas side end of the use side heat exchanger 52 passes through the use side gas refrigerant pipe 54, the gas refrigerant communication pipe 7, the gas side shut-off valve 30, and the second heat source side gas refrigerant pipe 33, again to the compressor. 21 is inhaled.

In this way, the cooling operation (refrigeration cycle operation) in the refrigeration apparatus 1 is performed.

(3) Expansion mechanism suitability determination process As described above, the refrigeration apparatus 1 is updated by replacing the existing heat source unit with the new heat source unit 2 while diverting the existing use unit 5. Moreover, in the update, the refrigerant is changed to a different one from the existing one. In this case, since a refrigerant different from the refrigerant before renewal flows through the existing use unit 5, the existing use-side expansion valve 51 (expansion mechanism) is considered in consideration of the difference in physical properties of the refrigerant before and after renewal. ) Cannot be used as it is, and it is necessary to select and replace the use side expansion valve 51 suitable for the renewed refrigerant.

However, when the refrigerating apparatus is updated including the replacement of the use side expansion valve 51, there is a possibility that selection mistakes or forgetting to replace the use side expansion valve 51 may occur. It is desirable to be able to determine whether or not an appropriate use side expansion valve 51 is provided in the circuit 10.

Therefore, the refrigeration apparatus 1 performs an expansion mechanism suitability determination process for determining whether or not the appropriate use-side expansion valve 51 is provided in the refrigerant circuit 10 during the first cooling operation after renewal (refrigeration cycle operation). . Next, the expansion mechanism suitability determination process will be described with reference to FIGS. Here, FIG. 3 is a flowchart showing the expansion mechanism suitability determination process, and FIG. 4 is a diagram showing a change with time of the low pressure LP or the evaporator outlet superheat degree SH during the cooling operation. In addition, the expansion mechanism suitability determination process described below is also performed by the control unit 8 that controls the components of the refrigeration apparatus 1.

First, in step ST <b> 1, the control unit 8 satisfies the first determination condition regarding the refrigerant, the compressor 21 and / or the state quantity of the use side expansion valve 51 when the opening degree of the use side expansion valve 51 is fluctuating. Determine if.

Here, the first determination condition is the cooling operation with the opening degree control of the use side expansion valve 51 based on the evaporator outlet superheat degree SH and the capacity control of the compressor 21 based on the low pressure LP in the refrigeration cycle. This is a condition for determining whether or not the operation amount is in an unstable state despite the fact that the opening degree of the use side expansion valve 51 performing the opening degree control is fluctuating. In this case, the operating state that satisfies the first determination condition is that the refrigerant circuit 10 is not provided with an appropriate use side expansion valve 51, and in particular, the valve diameter of the use side expansion valve 51 is in the refrigerant circuit 10. This is due to the fact that it is larger than the appropriate valve diameter. This is because if the use side expansion valve 51 having a valve diameter larger than an appropriate valve diameter is provided in the refrigerant circuit 10, the use side expansion valve 51 is often controlled in a small opening range, and therefore the use side expansion is performed. This is because the state quantity may be difficult to stabilize despite the valve opening control.

And as one of the first determination conditions, there is whether or not the fluctuation range of the evaporator outlet superheat degree SH exceeds the superheat degree fluctuation determination value ΔSHs. When the opening degree control of the use side expansion valve 51 is performed based on the evaporator outlet superheat degree SH, the opening degree control of the use side expansion valve 51 is performed when an appropriate use side expansion valve 51 is provided in the refrigerant circuit 10. As a result, the evaporator outlet superheat degree SH is stabilized, and the fluctuation range of the evaporator outlet superheat degree SH can be kept small. For example, the evaporator outlet superheat degree SH and the average of the evaporator outlet superheat degree SH within a predetermined time (for example, 10 minutes) like the change with time of the evaporator outlet superheat degree SH illustrated by the two-dot chain line in FIG. This is a case where the absolute value ΔSH of the difference from the value SHa does not exceed the superheat degree fluctuation determination value ΔSHs. On the other hand, if the appropriate use side expansion valve 51 is not provided in the refrigerant circuit 10 as in the case where the use side expansion valve 51 having a valve diameter larger than the appropriate valve diameter is provided in the refrigerant circuit 10, the use side expansion is performed. Despite the opening degree control of the valve 51, the evaporator outlet superheat degree SH is not stabilized, and the fluctuation range of the evaporator outlet superheat degree SH becomes large. For example, the fluctuation range ΔSH of the evaporator outlet superheat degree SH within a predetermined time (for example, 10 minutes) like the change with time of the evaporator outlet superheat degree SH illustrated by the solid line in FIG. This is the case when ΔSHs is exceeded. Thus, here, when the fluctuation range ΔSH of the evaporator outlet superheat degree SH exceeds the superheat degree fluctuation determination value ΔSHs, the fluctuation of the evaporator outlet superheat degree SH with respect to the opening degree fluctuation of the use side expansion valve 51. That is, it is determined that the opening degree control of the use side expansion valve 51 is being performed in a state where the pressure is large.

When the first determination condition based on the evaporator outlet superheat degree SH is satisfied, the control unit 8 proceeds to the process of step ST2 and uses the expansion on the use side having a valve diameter larger than the appropriate valve diameter. When the abnormality that the valve 51 is provided in the refrigerant circuit 10 is informed, and the first determination condition is not satisfied, the process proceeds to step ST3.

Further, another first determination condition is whether or not the fluctuation range ΔLP of the low-pressure pressure LP exceeds the low-pressure fluctuation determination value ΔLPs. In the case where the capacity control of the compressor 21 is performed based on the low pressure LP in the refrigeration cycle, if an appropriate use side expansion valve 51 is provided in the refrigerant circuit 10, the opening degree control of the use side expansion valve 51 is performed. Even if the low-pressure pressure LP fluctuates, the fluctuation range ΔLP is small. For example, the absolute value ΔLP of the difference between the low pressure LP and the target low pressure LPt within a predetermined time (for example, 10 minutes), such as the time-dependent change of the low pressure LP illustrated by the two-dot chain line in FIG. This is a case where the determination value ΔLPs is not exceeded. On the other hand, if the appropriate use side expansion valve 51 is not provided in the refrigerant circuit 10 as in the case where the use side expansion valve 51 having a valve diameter larger than the appropriate valve diameter is provided in the refrigerant circuit 10, the use side When the low pressure LP varies with the opening degree control of the expansion valve 51, the variation width ΔLP becomes large. For example, the variation range ΔLP of the low-pressure pressure LP within a predetermined time (for example, 10 minutes) exceeds the low-pressure variation determination value ΔLPs as in the time-dependent change of the low-pressure pressure LP illustrated by the solid line in FIG. Thus, here, when the fluctuation range ΔLP of the low-pressure pressure L exceeds the low-pressure fluctuation determination value ΔLPs, the use-side expansion is performed in a state where the fluctuation of the low-pressure pressure LP is large with respect to the opening degree fluctuation of the use-side expansion valve 51. It is determined that the opening degree control of the valve 51 is being performed.

And also when the control part 8 satisfy | fills the 1st determination conditions based on such low pressure LP, it transfers to the process of step ST2 and the utilization side expansion valve 51 of a larger valve diameter than an appropriate valve diameter is used. When the abnormality that the refrigerant circuit 10 is provided is notified and the first determination condition is not satisfied, the process proceeds to step ST3.

Here, as the first determination condition, the first determination condition based on the evaporator outlet superheat degree SH and the first determination condition based on the low pressure LP are adopted, but either one of the first determination conditions is adopted. Only conditions may be employed.

Next, in step ST3, the control unit 8 satisfies the second determination condition regarding the refrigerant, the compressor 21 and / or the state quantity of the use side expansion valve 51 when the opening degree of the use side expansion valve 51 is not changed. Determine whether or not.

Here, the second determination condition is that during the cooling operation involving the opening degree control of the use side expansion valve 51 based on the evaporator outlet superheat degree SH and the capacity control of the compressor 21 based on the low pressure LP in the refrigeration cycle, This is a condition for determining whether or not the operation state indicating an abnormal state quantity is in spite of the fact that the opening degree of the use side expansion valve 51 performing the opening degree control does not fluctuate. Here, the operating state that satisfies the second determination condition is that the appropriate use side expansion valve 51 is not provided in the refrigerant circuit 10, in particular, the valve diameter of the use side expansion valve 51 is in the refrigerant circuit 10. It is assumed that it is caused by being smaller than the appropriate valve diameter. Because, when the use side expansion valve 51 having a valve diameter smaller than an appropriate valve diameter is provided in the refrigerant circuit 10, the opening degree of the use side expansion valve 51 is often controlled in a larger opening range. This is because an abnormal state quantity may be shown even though the opening degree control of the use side expansion valve 51 is performed.

Then, as the second determination condition, whether or not the use side expansion valve 51 reaches the maximum opening degree (for example, the fully open opening degree) and the low pressure LP is lower than the target low pressure LPt, or the use side expansion valve 51 is set. Has reached the maximum opening (for example, full opening), and the capacity of the compressor 21 has reached the minimum capacity (for example, the minimum frequency Fcm). When the capacity control of the compressor 21 is performed so that the low pressure LP in the refrigeration cycle becomes the target low pressure LPt, if the appropriate use side expansion valve 51 is provided in the refrigerant circuit 10, the use side expansion valve 51 is maximum. In spite of the situation where the opening degree has been reached and the circulation flow rate of the refrigerant is likely to be increased, the low pressure LP does not become so low that it does not reach the target low pressure LPt, and the capacity of the compressor 21 reaches the minimum capacity. Since it does not decrease, it can be said that the range of opening degree control of the use side expansion valve 51 is wide. On the other hand, if the appropriate use side expansion valve 51 is not provided in the refrigerant circuit 10 as in the case where the use side expansion valve 51 having a valve diameter smaller than the appropriate valve diameter is provided in the refrigerant circuit 10, the use side expansion is performed. In spite of the situation where the valve 51 has reached the maximum opening and it is easy to increase the circulation flow rate of the refrigerant, the low pressure LP becomes lower than the target low pressure LPt, or the compressor 21 Therefore, it can be said that the range of opening degree control of the use side expansion valve 51 is narrow. Thus, here, when the use side expansion valve 51 reaches the maximum opening and the low pressure LP is lower than the target low pressure LPt, or the use side expansion valve 51 reaches the maximum opening and the compression is performed. When the capacity of the compressor 21 reaches the minimum capacity, the range of the opening degree control of the use side expansion valve 51 is narrow in performing the capacity control of the compressor 21 so that the low pressure LP becomes the target low pressure Lpt. It is judged that it is too much. In determining whether the second determination condition is satisfied, in order to suppress erroneous determination, the state of the low pressure LP and the capacity of the compressor 21 satisfying the above condition continues for a predetermined time (for example, 10 minutes). You may limit to.

When the second determination condition is satisfied, the control unit 8 proceeds to the process of step ST4, and the use side expansion valve 51 having a valve diameter smaller than an appropriate valve diameter is provided in the refrigerant circuit 10. When the second determination condition is not satisfied and the use side expansion valve 51 having an appropriate valve diameter is provided in the refrigerant circuit 10, the expansion mechanism is notified. The suitability determination process is terminated.

Thus, here, the refrigerant circuit is set according to the first determination condition and the second determination condition based on the state quantity appearing in accordance with the operating state (the presence or absence of opening degree variation) of the use side expansion valve 51 performing the opening degree control. 10, whether or not an appropriate use-side expansion valve 51 is provided can be determined.

In particular, here, in the cooling operation after renewal of the refrigeration apparatus including replacement of the use side expansion valve 51, it is determined whether or not the use side expansion valve 51 satisfies the first determination condition and the second determination condition. It is possible to discover whether or not a selection error or forgetting replacement has occurred. That is, in Steps ST1 and ST2, if an abnormality that the first determination condition is satisfied and the valve diameter is large is notified, the use-side expansion valve 51 has been replaced with one having a large valve diameter due to a selection error. In other words, it is possible to find out that there is a problem such as the use-side expansion valve 51 having been left forgotten to replace the use-side expansion valve 51 or being left with a large use-side expansion valve.

In addition, here, the evaporator outlet superheat degree SH or the low pressure LP is used as an indicator of whether or not the first determination condition is satisfied, and the evaporator outlet superheat degree by the opening degree control of the use side expansion valve 51 is used. It is possible to determine whether or not an appropriate use-side expansion valve 51 is provided in the refrigerant circuit 10 based on the degree of stability of SH and the degree of stability of the low pressure LP associated with the opening degree control of the use-side expansion valve 51. it can.

Further, here, the low pressure LP or the capacity of the compressor 21 is used as a state quantity serving as an index as to whether or not the second determination condition is satisfied, and the low pressure when the use side expansion valve 51 has reached the maximum opening degree. Based on the pressure LP and the capacity of the compressor 21, it can be determined whether or not the appropriate use side expansion valve 51 is provided in the refrigerant circuit 10.

(4) Modification <A>
In the above embodiment (see FIG. 3), the control unit 8 determines that the fluctuation range ΔSH of the evaporator outlet superheat degree SH exceeds the superheat degree fluctuation determination value ΔSHs or the low pressure LP in step ST1 of the expansion mechanism suitability determination process. When it is determined that the first determination condition is satisfied by the fluctuation width ΔLP exceeding the low pressure fluctuation determination value ΔLPs, the use side expansion valve 51 (expansion mechanism) having a valve diameter larger than an appropriate valve diameter in step ST2. Is informed that an abnormality has occurred in the refrigerant circuit 10.

However, even if such an abnormality of the use side expansion valve 51 occurs, it is possible to improve such an operating state, stabilize the cooling operation, and continue cooling the use side space. preferable.

Therefore, here, as shown in FIG. 5, when the control unit 8 determines that the first determination condition is satisfied in step ST1 of the expansion mechanism suitability determination process, in step ST5 together with the notification process of step ST2. In addition, control is performed to reduce the opening degree of the heat source side expansion valve 28 as the second expansion mechanism.

When the opening degree control of the heat source side expansion valve 28 (second expansion mechanism) is performed, the pressure of the refrigerant sent to the use side expansion valve 51 (expansion mechanism) on the downstream side can be reduced. The opening of the use side expansion valve 51 can be controlled within a larger opening range. As a result, it is possible to improve the operation state in which the state quantity is not stabilized only by the opening degree control of the use side expansion valve 51, that is, to reduce the fluctuation range of the evaporator outlet superheat degree SH and the fluctuation range ΔLP of the low pressure LP. And cooling operation can be stabilized.

In addition, here, the control unit 8 determines that the fluctuation range ΔSH of the evaporator outlet superheat degree SH is equal to or less than the superheat degree fluctuation determination value ΔSHs, or the fluctuation width ΔLP of the low pressure LP is equal to or less than the low pressure fluctuation determination value ΔLPs. Until now, control is performed to reduce the opening of the heat source side expansion valve 28 (second expansion mechanism). For this reason, the fluctuation range ΔSH of the evaporator outlet superheat degree SH and the fluctuation range ΔLP of the low pressure LP can be reliably reduced.

<B>
In the above-described embodiment and Modification A, the low pressure LP and the capacity of the compressor 21 are used as state quantities serving as an index as to whether or not the second determination condition is satisfied in step ST3 of the expansion mechanism suitability determination process. However, the present invention is not limited to this. For example, as the second determination condition, whether or not the second determination condition is satisfied may be used depending on whether or not the temperature difference ΔTr between the use-side air temperature Tr and the target value Trt exceeds the temperature difference determination value ΔTrs.

<C>
In the above embodiment and modifications A and B, the expansion mechanism suitability determination process is performed during the first cooling operation after renewal (refrigeration cycle operation), so that the use side expansion valve 51 (expansion mechanism) may be selected incorrectly or forgotten to be replaced. I try to find out if it has occurred. However, the use of the expansion mechanism suitability determination process is not limited to the discovery of selection mistake or forgetting to replace the use side expansion valve 51 at the initial stage of installation, and can be used for other purposes.

For example, the expansion mechanism suitability determination process during the cooling operation may be performed even after the expansion mechanism suitability determination process during the first cooling operation after the update. In this case, when the clogging of the valve hole inside the use side expansion valve 51 occurs, a state satisfying the second determination condition, that is, a state similar to the state when the valve diameter becomes small is shown. It can be determined whether or not an appropriate use-side expansion valve 51 is provided in the circuit 10. In addition, when abnormal wear of the valve body and the valve hole of the use side expansion valve 51 occurs, a state satisfying the first determination condition, that is, a state similar to that when the valve diameter becomes large is shown. It can be determined whether or not an appropriate use-side expansion valve 51 is provided in the circuit 10. Even in such a case, similarly to Modification A, the cooling operation is continued while covering the abnormality of the use side expansion valve 51 by performing control to reduce the opening degree of the heat source side expansion valve 28. can do.

<D>
In the above embodiment and modifications A to C (see FIG. 1), the refrigeration apparatus 1 that performs the cooling operation as the refrigeration cycle operation has been described as an example, but the present invention is not limited to this. For example, in order to perform the refrigeration cycle operation in which the use side heat exchanger 52 functions as a refrigerant radiator and the heat source side heat exchanger 23 functions as a refrigerant evaporator, Two heat source side

gas refrigerant pipes

31 and 32 are provided with a four-way switching valve so that the reverse cycle defrosting operation of the use side heat exchanger 52 can be performed or used for air conditioning applications (cooling operation and heating operation). The above-described expansion mechanism suitability determination process can also be applied to the refrigeration apparatus.

<E>
In the embodiment and the modifications A to D, only one usage unit 5 is used, but a plurality of usage units 5 may be used.

In the embodiment and the modifications A to D, the low pressure LP is converted into the evaporation temperature Te when the evaporator outlet superheat degree SH is obtained. However, the use side heat exchanger 52 (evaporator) is used. A temperature sensor may be provided to detect the evaporation temperature Te.

The present invention relates to a refrigerant circuit configured by connecting a compressor, a radiator, an expansion mechanism including an electric expansion valve, and an evaporator, and a refrigerant filled in the refrigerant circuit. The present invention can be widely applied to a refrigeration apparatus that includes a control unit that performs a refrigeration cycle operation that circulates in the order of a condenser, an expansion mechanism, and an evaporator.

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 8 Control part 10 Refrigerant circuit 21 Compressor 23 Heat source side heat exchanger (heat radiator)
28 Heat source side expansion valve (second expansion mechanism)
51 User-side expansion valve (expansion mechanism)
52 User-side heat exchanger (evaporator)

JP 2011-252623 A

Claims

A refrigerant circuit (10) configured by connecting a compressor (21), a radiator (23), an expansion mechanism (51) including an electric expansion valve, and an evaporator (52); In a refrigeration apparatus comprising a control unit (8) for performing a refrigeration cycle operation for circulating the refrigerant charged in a refrigerant circuit in the order of the compressor, the radiator, the expansion mechanism, and the evaporator,
The control unit is configured to control the opening degree of the expansion mechanism during the refrigeration cycle operation, and the refrigerant, the compressor, and / or the expansion when the opening degree of the expansion mechanism varies. Based on the first determination condition regarding the state quantity of the mechanism and / or the second determination condition regarding the state quantity of the refrigerant, the compressor and / or the expansion mechanism when the opening degree of the expansion mechanism is not changed. Determining whether or not the expansion mechanism is suitable for the refrigerant circuit.
Refrigeration equipment (1).
The control unit determines whether the valve diameter of the expansion mechanism is larger than a valve diameter appropriate for the refrigerant circuit based on the first determination condition, and determines whether the expansion mechanism is based on the second determination condition. Determining whether the valve diameter is smaller than the appropriate valve diameter for the refrigerant circuit;
The refrigeration apparatus according to claim 1.
The control unit performs opening degree control of the expansion mechanism based on an evaporator outlet superheat degree that is a superheat degree of the refrigerant at an outlet of the evaporator during the refrigeration cycle operation,
The control unit determines whether or not the first determination condition is satisfied based on whether or not a fluctuation range of the evaporator outlet superheat degree exceeds a superheat degree fluctuation determination value.
The refrigeration apparatus according to claim 1 or 2.
The control unit, during the refrigeration cycle operation, performs capacity control of the compressor based on the low pressure in the refrigeration cycle operation,
The controller determines whether or not the first determination condition is satisfied based on whether or not a fluctuation range of the low pressure exceeds a low pressure fluctuation determination value;
The refrigeration apparatus according to any one of claims 1 to 3.
The control unit performs capacity control of the compressor so that a low pressure in the refrigeration cycle operation becomes a target low pressure during the refrigeration cycle operation,
The control unit determines whether the expansion mechanism reaches a maximum opening and whether the low pressure is lower than the target low pressure, or the expansion mechanism reaches a maximum opening, and the compressor Determining whether the second determination condition is satisfied based on whether or not the capacity of
The refrigeration apparatus according to any one of claims 1 to 4.
The refrigerant circuit further includes a second expansion mechanism (28) between the radiator and the expansion mechanism,
The controller performs an operation of circulating the refrigerant charged in the refrigerant circuit in the order of the compressor, the radiator, the second expansion mechanism, the expansion mechanism, and the evaporator as the refrigeration cycle operation. And
The control unit performs control to reduce the opening of the second expansion mechanism when it is determined that the first determination condition is satisfied.
The refrigeration apparatus according to any one of claims 1 to 5.