WO2017138419A1

WO2017138419A1 - Refrigeration device

Info

Publication number: WO2017138419A1
Application number: PCT/JP2017/003661
Authority: WO
Inventors: 對比地　亮佑; 桑原　修; 豊明木屋; 森　徹
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2016-02-08
Filing date: 2017-02-01
Publication date: 2017-08-17
Also published as: CN108603697A; CN108603697B; JPWO2017138419A1; JP6653463B2

Abstract

In order to ensure refrigeration performance when a carbon dioxide refrigerant is used, this refrigeration device (R) has a refrigerant circuit configured from a compressor (11) having a first rotary compression element (14) and a second rotary compression element (16) driven by the same rotary shaft, a gas cooler (28), an electromagnetic expansion valve (39), and an evaporator (41), and is equipped with an electric expansion valve (33), a tank (36), a split heat exchanger (29), an electric expansion valve (43), an electric expansion valve (47), an electric expansion valve (70), an auxiliary circuit (48), a main circuit (38), a control device (57), an auxiliary compressor (60), a bypass circuit (73), and a return circuit (80). Refrigerant that has passed through the electric expansion valve (70) and a first flow path (29A) of the split heat exchanger (29) and/or refrigerant that has passed through the bypass circuit (73) is drawn into the auxiliary compressor (60).

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus in which a refrigerant circuit is constituted by a compression means, a gas cooler, a main throttle means, and an evaporator.

Conventionally, in a refrigeration system, a refrigeration cycle is constituted by a compression means, a gas cooler, a throttle means, an evaporator, etc., and the refrigerant compressed by the compression means dissipates heat in the gas cooler, and then is depressurized by the throttle means, and then in the evaporator Evaporate. The ambient air is cooled by the evaporation of the refrigerant at this time.

In recent years, in this type of refrigeration equipment, it has become impossible to use chlorofluorocarbon refrigerants due to natural environmental problems. For this reason, a refrigeration apparatus using carbon dioxide, which is a natural refrigerant, has been developed as an alternative to a fluorocarbon refrigerant. The carbon dioxide refrigerant is a refrigerant having a high and low pressure difference, and has a low critical pressure. It is known that the high pressure side of the refrigerant cycle is brought into a supercritical state by compression (for example, see Patent Document 1).

Further, in the heat pump device constituting the water heater, a carbon dioxide refrigerant capable of obtaining an excellent heating action in the gas cooler has been used. In this case, the refrigerant discharged from the gas cooler is expanded in two stages, There has also been developed an apparatus in which a gas-liquid separator is interposed between expansion devices to enable gas injection into a compressor (see, for example, Patent Document 2).

Japanese Patent Publication No. 7-18602 JP 2007-178042 A

However, in the refrigeration apparatus using the carbon dioxide refrigerant described above, for example, an evaporator installed in a showcase or the like uses an endothermic action to cool the interior, but the outside air temperature (heat source temperature on the gas cooler side) is high. For this reason, the refrigerant temperature at the outlet of the gas cooler may increase. In this case, since the specific enthalpy at the evaporator inlet increases, the refrigerating capacity significantly decreases.

An object of the present invention is to provide a refrigeration apparatus capable of ensuring a refrigeration capacity when a carbon dioxide refrigerant is used.

The refrigeration apparatus according to the present invention includes a refrigerant circuit including a compression unit having a first rotary compression element and a second rotary compression element driven by the same rotary shaft, a gas cooler, a main throttle unit, and an evaporator. In the refrigeration apparatus configured and using carbon dioxide refrigerant, the auxiliary compression means provided separately from the compression means, and connected to the refrigerant circuit downstream of the gas cooler and upstream of the main throttle means. A pressure adjusting throttle means for adjusting the pressure of the refrigerant flowing out of the gas cooler; a tank connected to the refrigerant circuit downstream of the pressure adjusting throttle means and upstream of the main throttle means; A split heat exchanger provided in the refrigerant circuit downstream of the tank and upstream of the main throttle means, having a first flow path and a second flow path; and a first height of the tank Provided The first auxiliary throttle means for adjusting the pressure of the refrigerant flowing out of the first pipe and the second pipe provided at a position lower than the first height, and the split heat exchanger After passing through the second flow path, the second auxiliary throttle means for adjusting the pressure of the first refrigerant out of the refrigerant diverted downstream of the second flow path, and outflow from the second pipe And a third auxiliary throttle means for adjusting the pressure of the second refrigerant among the refrigerants that are diverted downstream of the second flow path after passing through the second flow path of the split heat exchanger. An auxiliary circuit for sucking the refrigerant that has passed through the first flow path of the third auxiliary throttling means and the split heat exchanger into the auxiliary compression means, and an on-off valve, and flows out of the first pipe The first refrigerant of the split heat exchanger in the auxiliary circuit. A first bypass circuit that flows into the downstream side of the flow path, a refrigerant in which a refrigerant whose pressure is adjusted by the first auxiliary throttle means and a refrigerant whose pressure is adjusted by the second auxiliary throttle means are mixed. A return circuit that sucks into the intermediate pressure part of the compression means, and a refrigerant that has flowed out of the tank flows into the second flow path of the split heat exchanger, and flows through the first flow path of the split heat exchanger. A main circuit for flowing a third refrigerant out of the refrigerant diverted downstream of the second flow path into the main throttle means after heat exchange with the refrigerant, the compression means, the auxiliary compression means, Main throttle means, pressure adjusting throttle means, first auxiliary throttle means, second auxiliary throttle means, third auxiliary throttle means, and control means for controlling the operation of the on-off valve. Use a configuration to provide.

According to the present invention, the refrigeration capacity can be ensured when carbon dioxide refrigerant is used.

Refrigerant circuit diagram of a refrigerating apparatus of one embodiment to which the present invention is applied PH diagram showing the operating state of a refrigeration system not equipped with an auxiliary compressor PH diagram showing an operation state according to operation example 1 of the refrigeration apparatus PH diagram showing an operation state according to operation example 2 of the refrigeration apparatus Refrigerant circuit diagram of a refrigeration apparatus having a configuration different from that of FIG. PH diagram showing the operating state of the refrigeration apparatus shown in FIG. Refrigerant circuit diagram of a refrigeration apparatus having a configuration different from that of FIG. PH diagram showing the operating state of the refrigeration apparatus shown in FIG. Refrigerant circuit diagram of a refrigeration apparatus having a configuration different from that of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Refrigeration Apparatus R FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus R according to an embodiment to which the present invention is applied. The refrigeration apparatus R in this embodiment is a show of a refrigerator unit 3 installed in a machine room or the like of a store such as a supermarket, and one or a plurality of units (only one is shown in the drawing) installed in the store sales area. The refrigerator unit 3 and the showcase 4 are connected to each other by a refrigerant pipe (liquid pipe) 8 and a refrigerant pipe 9 via a unit outlet 6 and a unit inlet 7, and a predetermined refrigerant circuit 1 is provided. It is composed.

This refrigerant circuit 1 uses, as a refrigerant, carbon dioxide (R744) whose refrigerant pressure on the high pressure side can be higher than the critical pressure (supercritical). This carbon dioxide refrigerant is a natural refrigerant that is friendly to the global environment and takes into consideration flammability and toxicity. As the lubricating oil, existing oils such as mineral oil (mineral oil), alkylbenzene oil, ether oil, ester oil, and PAG (polyalkyl glycol) are used. Each arrow shown in FIG. 1 indicates the flow of the carbon dioxide refrigerant.

The refrigerator unit 3 includes a compressor 11 (an example of compression means). The compressor 11 is, for example, an internal intermediate pressure type two-stage compression rotary compressor. The compressor 11 includes a sealed container 12 and a rotary compression mechanism unit. The rotary compression mechanism section includes an electric element 13 as a drive element housed in the upper part of the internal space of the sealed container 12, and a first (low-stage) rotary compression element (lower stage side) disposed below the electric element 13. A first compression element) 14 and a second (higher stage) rotary compression element (second compression element) 16. The compressor 11 is a two-stage compressor having a first rotary compression element 14 and a second rotary compression element 16 driven by the same rotary shaft (the rotary shaft of the electric element 13). In such a two-stage compressor, the excluded volume ratio between the low stage side and the high stage side is determined, and the intermediate pressure (MP) is determined according to the excluded volume ratio.

The first rotary compression element 14 of the compressor 11 compresses the low-pressure refrigerant sucked into the compressor 11 from the low-pressure side of the refrigerant circuit 1 through the refrigerant pipe 9, boosts it to an intermediate pressure, and discharges it. The second rotary compression element 16 sucks in the intermediate pressure refrigerant discharged by the first rotary compression element 14, compresses it to a high pressure, and discharges it to the high pressure side of the refrigerant circuit 1. The compressor 11 is a variable frequency compressor. The control device 57 to be described later controls the rotation speed of the first rotary compression element 14 and the second rotary compression element 16 by changing the operating frequency of the electric element 13.

On the side surface of the sealed container 12 of the compressor 11, a low-stage suction port 17 communicating with the first rotary compression element 14, a low-stage discharge port 18 communicating with the inside of the sealed container 12, and a second rotary compression element 16. A high-stage suction port 19 and a high-stage discharge port 21 that communicate with each other are formed. One end of the refrigerant introduction pipe 22 is connected to the lower stage side suction port 17 of the compressor 11, and the other end is connected to the refrigerant pipe 9 at the unit inlet 7.

The low-pressure refrigerant gas sucked into the low-pressure portion of the first rotary compression element 14 from the low-stage suction port 17 is compressed to the first pressure by the first rotary compression element 14 to be increased to the intermediate pressure. The liquid is discharged into the sealed container 12. Thereby, the inside of the airtight container 12 becomes an intermediate pressure (MP).

One end of the intermediate pressure discharge pipe 23 is connected to the low-stage discharge port 18 of the compressor 11 from which the intermediate pressure refrigerant gas in the sealed container 12 is discharged, and the other end is connected to the inlet of the intercooler 24. Has been. The intercooler 24 air-cools the intermediate pressure refrigerant discharged from the first rotary compression element 14. One end of an intermediate pressure suction pipe 26 is connected to the outlet of the intercooler 24. The other end of the intermediate pressure suction pipe 26 is connected to the high stage side suction port 19 of the compressor 11.

The intermediate pressure (MP) refrigerant gas sucked into the second rotary compression element 16 from the high-stage side suction port 19 of the compressor 11 is compressed by the second rotary compression element 16 in the second stage, It becomes a high-temperature and high-pressure refrigerant gas.

In addition, one end of a high-pressure discharge pipe 27 is connected to the high-stage discharge port 21 provided on the high-pressure chamber side of the second rotary compression element 16 of the compressor 11, and the other end of a gas cooler (heat radiator) 28. Connected to the entrance. Although illustration is omitted, an oil separator 20 may be provided in the middle of the high-pressure discharge pipe 27. The oil separated from the refrigerant by the oil separator is returned to the sealed container 12 of the compressor 11 and the sealed container 61 of the auxiliary compressor 60.

The gas cooler 28 cools the high-pressure discharged refrigerant discharged from the compressor 11. A gas cooler blower 31 for air-cooling the gas cooler 28 is disposed in the vicinity of the gas cooler 28. In the present embodiment, the gas cooler 28 is juxtaposed with the intercooler 24 described above, and these are arranged in the same air passage.

One end of a gas cooler outlet pipe 32 is connected to the outlet of the gas cooler 28, and the other end of the gas cooler outlet pipe 32 is connected to the inlet of an electric expansion valve 33 (an example of a pressure adjusting throttle means).

The electric expansion valve 33 is located downstream of the gas cooler 28 and upstream of the electric expansion valve 39. The electric expansion valve 33 is used for restricting and expanding the refrigerant discharged from the gas cooler 28 and adjusting the high-pressure side pressure of the refrigerant circuit 1 upstream from the electric expansion valve 33. The outlet of the electric expansion valve 33 is connected to the upper part of the tank 36 via a tank inlet pipe 34.

The tank 36 is a volume body having a predetermined volume space therein. One end of a tank outlet pipe 37 is connected to the lower part of the tank 36, and the other end of the tank outlet pipe 37 is connected to the refrigerant pipe 8 at the unit outlet 6. In the middle of the tank outlet pipe 37, a second flow path 29B of the split heat exchanger 29 is provided. This tank outlet pipe 37 constitutes a main circuit 38 in the present embodiment. The tank 36 is located downstream of the electric expansion valve 33 and upstream of the electric expansion valve 39. The split heat exchanger 29 is located downstream of the tank 36 and upstream of the electric expansion valve 39.

One end of a gas pipe 42 is connected to the upper part of the tank 36. The other end of the gas pipe 42 is connected to the inlet of an electric expansion valve 43 (an example of a first auxiliary circuit throttle means). The gas pipe 42 causes the gas refrigerant to flow out from the upper part of the tank 36 and flow into the electric expansion valve 43. One end of an intermediate pressure return pipe 44 is connected to the outlet of the electric expansion valve 43. The other end of the intermediate pressure return pipe 44 communicates with the intermediate pressure suction pipe 26 connected to the intermediate pressure portion of the compressor 11.

Further, one end of the liquid pipe 46 is connected to the tank outlet pipe 37 on the downstream side of the second flow path 29B of the split heat exchanger 29. The other end of the liquid pipe 46 is connected to an intermediate pressure return pipe 44 on the downstream side of the electric expansion valve 43. In the middle of the liquid pipe 46, an electric expansion valve 47 (an example of a second auxiliary circuit throttle means) is provided.

Also, one end of the branch pipe 71 is connected to the tank outlet pipe 37 on the downstream side of the second flow path 29B of the split heat exchanger 29. The other end of the branch pipe 71 is connected to the suction port 64 of the auxiliary compressor 60. The configuration of the auxiliary compressor 60 will be described later.

In the middle of the branch pipe 71, an electric expansion valve 70 (an example of a third auxiliary circuit throttle means) is disposed. Further, in the middle of the branch pipe 71, a first flow path 29 </ b> A of the split heat exchanger 29 is provided on the downstream side of the electric expansion valve 70.

The branch pipe 71 is connected to the bypass circuit 73 on the downstream side of the first flow path 29A. The other end of the bypass circuit 73 is connected to the gas pipe 42. The bypass circuit 73 is provided with an electromagnetic valve 74. The electromagnetic valve 74 is controlled by the control device 57 to either the open state or the closed state.

The refrigerant that has passed through the second flow path 29B of the split heat exchanger 29 has three directions (the first refrigerant toward the electric expansion valve 47 and the first flow toward the electric expansion valve 70 on the downstream side of the second flow path 29B. 2 refrigerant, the third refrigerant heading toward the electric expansion valve 39).

The electric expansion valve 43 (first auxiliary circuit throttle means), the electric expansion valve 47 (second auxiliary circuit throttle means) and the electric expansion valve 70 (third auxiliary circuit throttle means) described above are The auxiliary aperture means in the embodiment is configured. The branch pipe 71 constitutes the auxiliary circuit 48 in the present embodiment. Further, the intermediate pressure return pipe 44 constitutes the return circuit 80 in the present embodiment.

The showcase 4 installed in the store is connected to the

refrigerant pipes

8 and 9. The showcase 4 is provided with an electric expansion valve 39 (an example of a main throttle means) and an evaporator 41, which are sequentially connected between the refrigerant pipe 8 and the refrigerant pipe 9 (the electric expansion valve 39 is Refrigerant pipe 8 side, evaporator 41 is refrigerant pipe 9 side). Next to the evaporator 41, a cool air circulation blower (not shown) for blowing air to the evaporator 41 is provided. The refrigerant pipe 9 is connected to the low-stage suction port 17 that communicates with the first rotary compression element 14 of the compressor 11 via the refrigerant introduction pipe 22 as described above.

The refrigerator unit 3 includes an auxiliary compressor 60 (an example of auxiliary compression means). The auxiliary compressor 60 includes an airtight container 61, an electric element 62 as a driving element housed in the internal space of the airtight container 61, and a rotary compression element 63 that is driven by the rotation shaft of the electric element 62. Yes.

A suction port 64 and a discharge port 65 communicating with the rotary compression element 63 are formed on the side surface of the sealed container 61. One end of a branch pipe 71 is connected to the suction port 64. The discharge port 65 is connected to one end of a pipe 72. The other end of the pipe 72 is connected to the high pressure discharge pipe 27.

The rotary compression element 63 compresses the refrigerant sucked from the branch pipe 71, raises the pressure to high pressure, and discharges it to the high pressure side of the refrigerant circuit 1. The auxiliary compressor 60 is a variable frequency compressor. The control device 57 described later controls the rotational speed of the rotary compression element 63 by changing the operating frequency of the electric element 62.

Various sensors are attached to various parts of the refrigerant circuit 1.

For example, a high pressure sensor 49 is attached to the high pressure discharge pipe 27. The high pressure sensor 49 detects the high pressure side pressure HP of the refrigerant circuit 1 (pressure between the high stage discharge port 21 of the compressor 11 and the inlet of the electric expansion valve 33).

Further, for example, a low pressure sensor 51 is attached to the refrigerant introduction pipe 22. The low pressure sensor 51 detects the low pressure LP of the refrigerant circuit 1 (pressure between the outlet of the electric expansion valve 39 and the low stage suction port 17).

Further, for example, an intermediate pressure sensor 52 is attached to the intermediate pressure return pipe 44. The intermediate pressure sensor 52 is an intermediate pressure MP (pressure in the intermediate pressure return pipe 44 downstream from the outlets of the

electric expansion valves

43 and 47, which is the pressure in the intermediate pressure region 1 of the refrigerant circuit, and is low in the compressor 11. A pressure equal to the pressure between the stage side discharge port 18 and the high stage side suction port 19) is detected.

For example, a unit outlet sensor 53 is attached to the tank outlet pipe 37 on the downstream side of the split heat exchanger 29. The unit outlet sensor 53 detects the pressure OP in the tank 36. The pressure in the tank 36 becomes the pressure of the refrigerant that leaves the refrigerator unit 3 and flows into the electric expansion valve 39 from the refrigerant pipe 8.

Each sensor described above is connected to the input of the control device 57 (an example of the control means) of the refrigerator unit 3 composed of a microcomputer. On the other hand, the output of the control device 57 includes the electric element 13 of the compressor 11, the electric element 62 of the auxiliary compressor 60, the gas cooler blower 31, the electric expansion valve 33, the electric expansion valve 43, the electric expansion valve 47, and the electric expansion valve. 70, the electric expansion valve 39, and the electromagnetic valve 74 are connected. The control device 57 controls each component on the output side based on detection results from each sensor, setting data, and the like.

In the following description, it is assumed that the electric expansion valve 39 on the showcase 4 side and the above-described cool air circulation blower are also controlled by the control device 57, but these are controlled via the main control device (not shown) of the store. It is good also as being controlled by the control apparatus (illustration omitted) by the side of the showcase 4 which cooperates with 57. Therefore, the control means in this embodiment may be a concept including the control device 57, the control device on the showcase 4 side, the main control device described above, and the like.

(2) Operation of Refrigeration Apparatus R Next, the operation of the refrigeration apparatus R will be described. When the electric element 13 of the compressor 11 is driven by the control device 57, the first rotary compression element 14 and the second rotary compression element 16 are rotated, and the first rotary compression element 14 is rotated from the low-stage suction port 17. Low-pressure refrigerant gas (carbon dioxide) is sucked into the low-pressure part. Then, the pressure is increased to an intermediate pressure by the first rotary compression element 14 and discharged into the sealed container 12. Thereby, the inside of the airtight container 12 becomes an intermediate pressure (MP).

Then, the intermediate-pressure gas refrigerant in the sealed container 12 enters the intercooler 24 through the intermediate-pressure discharge pipe 23 from the low-stage discharge port 18 and is air-cooled in the intercooler 24.

The air-cooled gas refrigerant flows out from the intercooler 24 to the intermediate pressure suction pipe 26, and in the intermediate pressure suction pipe 26, the gas refrigerant flows into the intermediate pressure suction pipe 26 from the intermediate pressure return pipe 44 (details will be described later). Mix. The mixed gas refrigerant flows into the high stage suction port 19 (intermediate pressure part) of the compressor 11.

The intermediate-pressure gas refrigerant that has flowed into the high-stage side suction port 19 is sucked into the second rotary compression element 16, and the second-stage compression is performed by the second rotary compression element 16, so that the high-temperature and high-pressure gas refrigerant is obtained. It becomes. This gas refrigerant is discharged from the high-stage discharge port 21 to the high-pressure discharge pipe 27.

(2-1) Control of the electric expansion valve 33 The gas refrigerant flowing into the gas cooler 28 from the high pressure discharge pipe 27 is cooled by the gas cooler 28 and then reaches the electric expansion valve 33 through the gas cooler outlet pipe 32. The electric expansion valve 33 is provided to control the high-pressure side pressure HP of the refrigerant circuit 1 upstream of the electric expansion valve 33 to a predetermined target value THP, and based on the output of the high-pressure sensor 49, the control device 57. Is used to control the valve opening.

(2-1-1) Setting of opening degree of electric expansion valve 33 when starting operation First, when starting the operation, the controller 57 opens the opening degree (starting of the electric expansion valve 33 when starting the refrigeration apparatus R based on the outside air temperature). Set the valve opening. Specifically, in the present embodiment, the control device 57 stores in advance a data table showing the relationship between the outside air temperature at the time of starting and the valve opening degree at the time of starting the electric expansion valve 33, and the outside air at the time of starting is stored. From the temperature, the opening degree of the electric expansion valve 33 at the start is set with reference to the data table.

Note that the outside air temperature is detected by, for example, an outside temperature sensor (not shown). The outside air temperature sensor is disposed inside or in the vicinity of an outdoor unit in which the intercooler 24, the gas cooler 28, the gas cooler blower 31 and the like are stored. Not limited to this, the control device 57 may detect the outside air temperature from the high-pressure side pressure HP detected by the high-pressure sensor 49 (hereinafter the same). Since there is a correlation between the high pressure side pressure HP detected by the high pressure sensor 49 and the outside air temperature, the controller 57 can determine the outside temperature from the high pressure side pressure HP. Specifically, the control device 57 stores in advance a data table indicating the relationship between the high-pressure side pressure HP (outside air temperature) at the time of starting and the valve opening degree at the time of starting the electric expansion valve 33. The outside air temperature is estimated, and the valve opening degree at the start of the electric expansion valve 33 is set with reference to the data table.

(2-1-2) Setting of the opening degree of the electric expansion valve 33 during operation During operation, the control device 57 is based on the detected pressure (high pressure side pressure HP) of the high pressure sensor 49 which is an index indicating the outside air temperature. The opening degree of the electric expansion valve 33 is set. In this case, the control device 57 sets the opening degree of the electric expansion valve 33 so as to increase when the high-pressure side pressure HP (outside air temperature) is low. Thereby, the pressure drop in the electric expansion valve 33 can be suppressed to a minimum, a pressure difference from the intermediate pressure (MP) of the intermediate pressure suction pipe 26 entering the compressor 11 is secured, and the refrigeration operation and the refrigeration operation are performed. Can be done efficiently.

Here, the control device 57 stores in advance a data table showing the relationship between the high pressure side pressure HP (outside air temperature) and the opening degree of the electric expansion valve 33, and by referring to it, the control device 57 opens the electric expansion valve 33. The degree may be set, or the opening degree may be calculated from a calculation formula.

(2-1-3) Control with the upper limit value MHP of the high pressure side pressure HP When the control is performed as described above, the high pressure side pressure upstream of the electric expansion valve 33 due to the influence of the installation environment and load. When HP has increased to the predetermined upper limit value MHP, the control device 57 further increases the valve opening degree of the electric expansion valve 33. As the valve opening increases, the high-pressure side pressure HP tends to decrease, so that the high-pressure side pressure HP can always be kept below the upper limit value MHP. As a result, it is possible to reliably suppress the abnormal increase in the high-pressure side pressure HP upstream from the electric expansion valve 33 and to reliably protect the compressor 11, and to forcibly stop (protect) the compressor 11 due to an abnormal high pressure. Operation) can be avoided in advance.

Here, the supercritical refrigerant gas from the gas cooler 28 is decompressed by the electric expansion valve 33 to be in a gas-liquid two-phase mixed state, and flows into the tank 36 from above through the tank inlet pipe 34. The tank 36 temporarily stores and separates the liquid / gas refrigerant flowing in from the tank inlet pipe 34, and the high pressure side pressure of the refrigeration apparatus R (in this case, the compressor 11 upstream from the tank 36 to the compressor 11. In the region up to the high-pressure discharge pipe 27) and absorbs fluctuations in the circulation amount of the refrigerant.

The liquid refrigerant accumulated in the lower part of the tank 36 flows out from the tank 36 to the tank outlet pipe 37 (main circuit 38). Hereinafter, the flow of the refrigerant flowing out from the tank 36 to the tank outlet pipe 37 will be described.

The liquid refrigerant that has flowed out of the tank 36 flows into the second flow path 29B of the split heat exchanger 29, and is cooled (supercooled) by the refrigerant flowing through the first flow path 29A in the second flow path 29B. Thereafter, the liquid refrigerant exits the refrigerator unit 3 and flows into the electric expansion valve 39 from the refrigerant pipe 8.

The refrigerant that has flowed into the electric expansion valve 39 is expanded by being throttled by the electric expansion valve 39, so that the liquid content further increases and flows into the evaporator 41 to evaporate. The cooling effect is exhibited by the endothermic action. The control device 57 controls the degree of superheat of the refrigerant in the evaporator 41 by controlling the valve opening degree of the electric expansion valve 39 based on the output of a temperature sensor (not shown) that detects the temperatures of the inlet side and the outlet side of the evaporator 41. Adjust to the appropriate value.

The low-temperature gas refrigerant discharged from the evaporator 41 returns from the refrigerant pipe 9 to the refrigerator unit 3, passes through the refrigerant introduction pipe 22, and communicates with the first rotary compression element 14 of the compressor 11. Sucked into. The above is the flow of the refrigerant in the main circuit 38.

(2-2) Control of the electric expansion valve 43 The flow of the refrigerant in the return circuit 80 will be described. The temperature of the gas refrigerant that accumulates in the upper part of the tank 36 is lowered due to the decompression of the electric expansion valve 33. This gas refrigerant flows out from the tank 36 to the gas pipe 42. As described above, the electric expansion valve 43 is connected to the gas pipe 42. After being throttled by the electric expansion valve 43, the gas refrigerant flows into the intermediate pressure return pipe 44 and mixes with the refrigerant that has passed through the electric expansion valve 47. Then, the refrigerant flows into the intermediate pressure suction pipe 26 from the intermediate pressure return pipe 44, mixes with the refrigerant discharged from the intercooler 24, and is sucked into the high-stage suction port 19 of the compressor 11.

The electric expansion valve 43 functions to adjust the pressure in the tank 36 (the pressure of the refrigerant flowing into the electric expansion valve 39) to a predetermined target value SP in addition to the function of restricting the refrigerant flowing out from the upper portion of the tank 36. . Then, the control device 57 controls the valve opening degree of the electric expansion valve 43 based on the output of the unit outlet sensor 53. This is because if the valve opening degree of the electric expansion valve 43 increases, the amount of gas refrigerant flowing out of the tank 36 increases and the pressure in the tank 36 decreases.

In the present embodiment, the target value SP is set to a value lower than the high pressure side pressure HP and higher than the intermediate pressure MP. Then, the control device 57 adjusts the valve opening degree of the electric expansion valve 39 from the difference between the pressure OP in the tank 36 (pressure of the refrigerant flowing into the electric expansion valve 39) detected by the unit outlet sensor 53 and the target value SP. (Step number) is calculated and added to a valve opening at the time of starting, which will be described later, to control the pressure OP in the tank 36 to the target value SP. That is, when the pressure OP in the tank 36 rises above the target value SP, the valve opening degree of the electric expansion valve 43 is increased to cause the gas refrigerant to flow out from the tank 36 to the gas pipe 42, and conversely, the target value SP. When the valve is further lowered, the valve opening is reduced and controlled to close.

(2-2-1) Setting of Opening at Operation Start of Electric Expansion Valve 43 The control device 57 sets the outside air temperature or the detected pressure (high pressure side pressure HP) of the high pressure sensor 49 as an index indicating the outside air temperature. Based on this, the valve opening degree of the electric expansion valve 43 when starting the refrigeration apparatus R (the valve opening degree when starting) is set. In the case of the present embodiment, the control device 57 stores in advance a data table indicating the relationship between the outside air temperature at the time of starting or the high pressure side pressure HP (outside air temperature) and the opening degree of the electric expansion valve 43 at the time of starting. Yes.

Then, the controller 57 increases from the outside air temperature at the time of starting or the detected pressure (high pressure side pressure HP) as the high pressure side pressure HP (outside air temperature) is high based on the data table, and conversely, the high pressure side pressure. The opening degree of the electric expansion valve 43 at the time of starting is set so as to decrease as HP decreases. Thereby, it is possible to suppress an increase in the pressure in the tank 36 at the time of start-up in an environment where the outside air temperature is high, and to prevent an increase in the pressure of the refrigerant flowing into the electric expansion valve 39.

In the present embodiment, the target value SP of the pressure OP in the tank 36 is fixed and controlled. However, as in the case of the electric expansion valve 33, the outside air temperature or the high pressure sensor 49 that is an index indicating the outside air temperature is used. The target value SP may be set based on the detected pressure (high pressure side pressure HP). In this case, the controller 57 becomes higher as the outside air temperature or the high pressure side pressure HP is higher. Therefore, in an environment where the outside air temperature is high, the target value SP during operation of the pressure of the refrigerant flowing into the electric expansion valve 39 becomes high.

In other words, in a situation where the pressure increases due to the influence of a high outside air temperature, the intermediate pressure MP increases, so that it is possible to prevent the inconvenience that the refrigerant does not easily flow to the return circuit 80 even if the valve opening degree of the electric expansion valve 43 increases. Will be able to. Conversely, by reducing the valve opening degree of the electric expansion valve 43, the amount of refrigerant flowing into the return circuit 80 can be reduced, and the disadvantage that the refrigerant pressure at the unit outlet 6 is reduced can be prevented. As a result, regardless of the change in the outside air temperature due to seasonal changes, the valve opening degree of the electric expansion valve 43 can be appropriately controlled to suppress the change in the refrigerant pressure at the unit outlet 6, and the amount of refrigerant can be accurately determined. Can be adjusted.

(2-2-2) Control of tank internal pressure OP at specified value MOP Note that when the control is performed as described above, the internal pressure OP of the tank 36 (in the electric expansion valve 39) due to the influence of the installation environment and load. When the pressure of the refrigerant flowing in) has increased to a predetermined specified value MOP, the control device 57 increases the valve opening degree of the electric expansion valve 43 by a predetermined step. As the valve opening increases, the pressure OP in the tank 36 decreases, so that the pressure OP can always be maintained below the specified value MOP. It becomes possible to reliably achieve the effect of suppressing the pressure of the refrigerant conveyed to the valve 39.

(2-3) Control of Electric Expansion Valve 47 The flow of the refrigerant in the return circuit 80 will be described. The liquid refrigerant that accumulates in the lower part of the tank 36 flows into the tank outlet pipe 37 from the tank 36, and is divided after passing through the second flow path 29B. One of the divided liquid refrigerant flows into the liquid pipe 46 and is throttled by the electric expansion valve 47. Thereafter, the liquid refrigerant flows into the intermediate pressure return pipe 44 and is mixed with the refrigerant that has passed through the electric expansion valve 43. Then, the refrigerant flows into the intermediate pressure suction pipe 26 from the intermediate pressure return pipe 44, mixes with the refrigerant discharged from the intercooler 24, and is sucked into the high-stage suction port 19 of the compressor 11.

The valve opening degree of the electric expansion valve 47 is set by the control device 57. For example, the control device 57 sets the electric expansion valve 47 to an open state when the temperature (discharge temperature) of the refrigerant discharged from the high-stage discharge port 21 of the compressor 11 is higher than the target value. The discharge temperature is detected by a discharge temperature sensor (not shown) and input to the control device 57.

(3-1) Control of Electric Expansion Valve 70 and Electromagnetic Valve 74 In this embodiment, the control device 57 controls the opening and closing of the electric expansion valve 70 and the electromagnetic valve 74, so that the flow of refrigerant flowing out of the tank 36 is controlled. Can be switched. Hereinafter, each of the operation example 1 and the operation example 2 will be described.

<Operation example 1>
In this operation example, the electric expansion valve 70 is set to the closed state (the valve opening is zero) by the control device 57, and the electromagnetic valve 74 is set to the open state (an example of the first setting). . In this case, the refrigerant flowing out of the tank 36 is as follows.

The refrigerant flowing into the tank outlet pipe 37 from the tank 36 passes through the second flow path 29B of the split heat exchanger 29 and then does not flow through the branch pipe 71 because the electric expansion valve 70 is closed. It flows into each of the expansion valve 47 and the electric expansion valve 39.

Further, the refrigerant flowing from the tank 36 into the gas pipe 42 is branched in the gas pipe 42.

One of the refrigerants divided in the gas pipe 42 is throttled by the electric expansion valve 43 as described above, and then flows into the intermediate pressure return pipe 44 and mixes with the refrigerant passed through the electric expansion valve 47 to return to the intermediate pressure. It flows into the intermediate pressure suction pipe 26 from the pipe 44. Thereafter, the refrigerant is mixed with the refrigerant from the intercooler 24 and is sucked into the high-stage suction port 19 of the compressor 11 from the intermediate pressure suction pipe 26. The sucked refrigerant is compressed by the second rotary compression element 16 and becomes a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure refrigerant is discharged from the high-stage discharge port 21 and flows into the high-pressure discharge pipe 27.

The other refrigerant separated in the gas pipe 42 flows into the bypass circuit 73, passes through the open electromagnetic valve 74, and flows into the branch pipe 71. Thereafter, the refrigerant is sucked from the branch pipe 71 into the suction port 64 of the auxiliary compressor 60. When the electric element 62 of the auxiliary compressor 60 is driven by the control device 57, the rotary compression element 63 rotates. Thereby, the sucked refrigerant is compressed by the rotary compression element 63 and becomes a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure refrigerant flows into the high-pressure discharge pipe 27 from the discharge port 65 via the pipe 72 and is mixed with the refrigerant discharged from the high-stage discharge port 21 of the compressor 11.

Next, effects obtained by this operation example will be described with reference to FIGS.

FIG. 2 is a PH diagram showing an operating state of a refrigeration apparatus not equipped with an auxiliary compressor in a high temperature environment. For example, the refrigeration apparatus excludes the auxiliary compressor 60, the electric expansion valve 70, the branch pipe 71, the pipe 72, the bypass circuit 73, and the electromagnetic valve 74 from the configuration of FIG. 1 and splits in the middle of the intermediate pressure return pipe 44. The first flow path 29A of the heat exchanger 29 is provided. On the other hand, FIG. 3 is a PH diagram showing an operating state of the refrigeration apparatus R in a high temperature environment. The high temperature environment is, for example, an environment where the outside air temperature is about 32 degrees Celsius (for example, summer).

2 and 3, the line from X1 to X2, the line from X3 to X4, the line from X5 to X6, and the line from X3 to X8 are respectively an electric expansion valve 33, an electric expansion valve 39, The decompression by the electric expansion valve 43 and the electric expansion valve 47 is shown. Further, the line diagonally upward from X5 indicates the pressure increase by the auxiliary compressor 60, and the line diagonally upward from X11 indicates the pressure increase by the compressor 11.

2 and 3, X9 indicates the specific enthalpy / pressure when the refrigerant having passed through the electric expansion valve 43 and the refrigerant having passed through the electric expansion valve 47 are mixed. X11 represents the specific enthalpy / pressure when the refrigerant flowing through the intermediate pressure suction pipe 26 flows into the high-stage suction port 19 of the compressor 11. 3 indicates the specific enthalpy / pressure when flowing into the suction port 64 of the auxiliary compressor 60.

As described above, in the two-stage compressor in which the first rotary compression element and the second rotary compression element are driven by the same rotary shaft, the excluded volume ratio of the low stage side and the high stage side is determined. The intermediate pressure is determined according to the excluded volume ratio. Therefore, it was not possible to increase the refrigerant suction amount (excluded volume) only on the high stage side to lower the intermediate pressure.

On the other hand, in the refrigeration apparatus R according to the present embodiment, the auxiliary compressor 60 is provided separately from the compressor 11 that is a two-stage compressor, and the electromagnetic valve 74 of the bypass circuit 73 is opened, so that the high stage side Only the refrigerant suction amount (excluded volume) is increased. Thereby, even if the excluded volume ratio in the compressor 11 is determined, the intermediate pressure can be reduced.

As is clear from the comparison between FIG. 2 and FIG. 3, the pressure OP in the tank 36 (pressure at X3) can be reduced by reducing the intermediate pressure. Thereby, the specific enthalpy at the outlet of the tank 36 can be reduced, and the refrigerating capacity can be ensured. Further, the pressure OP in the tank 36 can be prevented from exceeding the critical pressure CP in a high temperature environment, and gas-liquid separation can be performed. Further, protection control (for example, medium pressure cut, step-out, etc.) forcibly stopping the compressor 11 at a predetermined high pressure value (abnormally high pressure) can be avoided, and stable operation of the refrigeration apparatus R can be realized.

<Operation example 2>
In this operation example, the electric expansion valve 70 is set to an open state (a state in which the valve opening is larger than zero) and the electromagnetic valve 74 is set to a closed state by the control device 57 (an example of a second setting). ). In this case, the refrigerant flowing out of the tank 36 is as follows.

The refrigerant that has flowed into the gas pipe 42 from the tank 36 flows into the electric expansion valve 43 without flowing through the bypass circuit 73 because the electromagnetic valve 74 is closed. Then, as described above, the refrigerant is throttled by the electric expansion valve 43, then flows into the intermediate pressure return pipe 44 and mixes with the refrigerant that has passed through the electric expansion valve 47, and the intermediate pressure suction pipe 26 passes through the intermediate pressure return pipe 44. Flow into. Thereafter, the refrigerant is mixed with the refrigerant from the intercooler 24 and is sucked into the high-stage suction port 19 of the compressor 11 from the intermediate pressure suction pipe 26. The sucked refrigerant is compressed by the second rotary compression element 16 and becomes a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure refrigerant is discharged from the high-stage discharge port 21 and flows into the high-pressure discharge pipe 27.

Further, the refrigerant flowing into the tank outlet pipe 37 from the tank 36 passes through the second flow path 29B of the split heat exchanger 29 and then is divided into three.

One of the refrigerants divided into three after passing through the second flow path 29B flows into the electric expansion valve 39.

Further, one of the refrigerants divided into three after passing through the second flow path 29B flows into the liquid pipe 46, is throttled by the electric expansion valve 47, and then flows into the intermediate pressure return pipe 44, The refrigerant is mixed with the refrigerant that has passed through the electric expansion valve 43.

In addition, one of the refrigerants branched after passing through the second flow path 29B flows into the electric expansion valve 70 and is throttled by the electric expansion valve 70, and then the first flow path of the split heat exchanger 29. Flows into 29A where it evaporates. The supercooling of the refrigerant flowing through the second flow path 29B is increased by the endothermic action at this time. Then, the refrigerant that has passed through the first flow path 29 </ b> A is sucked into the suction port 64 of the auxiliary compressor 60 from the branch pipe 71. When the electric element 62 of the auxiliary compressor 60 is driven by the control device 57, the rotary compression element 63 rotates. Thereby, the sucked refrigerant is compressed by the rotary compression element 63 and becomes a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure refrigerant flows into the high-pressure discharge pipe 27 from the discharge port 65 via the pipe 72 and is mixed with the refrigerant discharged from the high-stage discharge port 21 of the compressor 11.

In this operation example, the control device 57 adjusts the amount of liquid refrigerant flowing through the first flow path 29A of the split heat exchanger 29 by controlling the electric expansion valve 70 to be in an open state. Here, the example of control of the valve opening degree of the electric expansion valve 70 in this operation example will be described.

For example, the control device 57 first determines the temperature of the outlet of the second flow path 29B of the split heat exchanger 29 (hereinafter referred to as outlet temperature based on the temperature of the showcase 4; for example, at X3 in FIG. Temperature). Next, the control device 57 determines a temperature at which the refrigerant is evaporated in the split heat exchanger 29 (hereinafter referred to as an evaporation temperature; for example, a temperature at X13 in FIG. 4 described later) as a temperature lower than the outlet temperature. And the control apparatus 57 sets the valve opening degree of the electric expansion valve 70 so that the temperature of the refrigerant | coolant of the 1st flow path 29A may become evaporation temperature.

Next, the effect obtained by this operation example will be described with reference to FIG.

FIG. 4 is a PH diagram showing an operating state of the refrigeration apparatus R in a high temperature environment. The high temperature environment is, for example, an environment where the outside air temperature is about 32 degrees Celsius (for example, summer).

4, the same elements as those in FIGS. 2 and 3 are denoted by the same reference numerals. A line from X3 to X13 indicates pressure reduction by the electric expansion valve 70. The dotted line L1 indicates the specific enthalpy / pressure until the refrigerant throttled by the electric expansion valve 70 flows out of the electric expansion valve 70, flows through the compression by the auxiliary compressor 60, and flows into the high-pressure discharge pipe 27.

As is clear from the lines from X2 to X3 shown in FIGS. 3 and 4, in this operation example, a greater degree of supercooling can be ensured, so that the refrigerating capacity can be ensured. However, in this operation example, since the intermediate pressure is fixed at the excluded volume ratio of the compressor 11, for example, when the outside air temperature is high or the cooling condition of the showcase 4 is set to the middle temperature range, the intermediate pressure is intermediate. When the pressure rises, protection control (for example, medium pressure cut, step out, etc.) becomes necessary.

(3-2) Switching control between operation example 1 and operation example 2 For example, the control device 57 responds to an operation performed by the user (an operation to instruct which operation example 1 or operation example 2 is executed). You may control to perform either the operation example 1 or the operation example 2.

Or, for example, the control device 57 normally controls to execute the operation example 2, and when the intermediate pressure MP detected by the intermediate pressure sensor 52 becomes higher than a preset threshold value, the operation example 2 You may control to switch to the operation example 1. Thereby, an intermediate pressure can be reduced, without performing protection control.

Note that the control device 57 may switch between the operation example 1 and the operation example 2 in accordance with the outside air temperature, the cooling condition of the showcase 4, and the like.

The operation example 1 and the operation example 2 have been described above. The refrigerating apparatus R of the present embodiment can obtain the following effects in addition to the effects obtained by the operation example 1 and the operation example 2 described above.

In the refrigeration apparatus R of the present embodiment, since the pressure of the refrigerant sent to the showcase 4 is reduced, the design pressure of the piping can be lowered and a thin-walled tube can be used.

Further, in the refrigeration apparatus R of the present embodiment, the liquid refrigerant is held in the tank 36 and the amount thereof can be continuously changed. Therefore, the amount of refrigerant circulating in the refrigeration circuit 1 can be stably maintained at an appropriate amount.

Moreover, in the refrigeration apparatus R of the present embodiment, the necessary supercooling degree can be ensured by including the tank 36, the

electric expansion valves

43 and 47, and the split heat exchanger 29 that function as an economizer.

In the present embodiment, the configuration of the refrigeration apparatus R illustrated in FIG. 1 has been described, but the configuration of the refrigeration apparatus R is not limited to that illustrated in FIG. Hereinafter, another configuration example of the refrigeration apparatus R will be described.

(4) Another configuration example 1 of the refrigeration apparatus R
FIG. 5 is a refrigerant circuit diagram of a refrigeration apparatus R having a configuration different from that of FIG. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted below.

5 includes an electric expansion valve 75 in place of the electromagnetic valve 74 in the bypass circuit 73 shown in FIG.

In this operation example, the control device 57 sets the electric expansion valve 70 and the electric expansion valve 75 to an open state (a state where the valve opening is larger than zero) (an example of a third setting).

The valve opening degree of the electric expansion valve 70 is set as follows, for example. First, the control device 57 determines the outlet temperature of the second flow path 29B of the split heat exchanger 29 (for example, the temperature at X3 in FIG. 6 described later) based on the temperature of the showcase 4. Next, the control device 57 determines an evaporation temperature at which the refrigerant is evaporated in the split heat exchanger 29 (for example, a temperature at X15 in FIG. 6 described later) as a temperature lower than the outlet temperature. And the control apparatus 57 sets the valve opening degree of the electric expansion valve 70 so that the temperature of the refrigerant | coolant of the 1st flow path 29A may become evaporation temperature.

The valve opening degree of the electric expansion valve 75 is set as follows, for example. The control device 57 is based on the intermediate pressure detected by the intermediate pressure sensor 52 and the temperature of the refrigerant discharged from the auxiliary compressor 60 (hereinafter referred to as a discharge refrigerant temperature; detected by a sensor not shown). A valve opening of 75 is set. For example, when the detected intermediate pressure is higher than the target value and the detected discharged refrigerant temperature is lower than the target value, the control device 57 controls the electric expansion valve 75 to be closed.

Next, the effect obtained by the operation of this configuration example will be described with reference to FIG.

FIG. 6 is a PH diagram showing an operating state of the refrigeration apparatus R in a high temperature environment. The high temperature environment is, for example, an environment where the outside air temperature is about 32 degrees Celsius (for example, summer).

6, the same elements as those in FIGS. 2 and 3 are denoted by the same reference numerals. A line from X3 to X15 indicates pressure reduction by the electric expansion valve 70. A dotted line L2 indicates a specific enthalpy / pressure until the refrigerant throttled by the electric expansion valve 70 flows out of the electric expansion valve 70, flows through the compression by the auxiliary compressor 60, and flows into the high-pressure discharge pipe 27.

As is clear from a comparison between FIG. 3 (Operation Example 1) and FIG. 6, in the operation of this configuration example, the intermediate pressure is higher than that in Operation Example 1, but the degree of supercooling can be ensured. Further, as apparent from a comparison between FIG. 4 (Operation Example 2) and FIG. 6, the operation of this configuration example cannot secure the degree of supercooling, but can reduce the intermediate pressure, compared to Operation Example 2.

(5) Another configuration example 2 of the refrigeration apparatus R
FIG. 7 is a refrigerant circuit diagram of a refrigeration apparatus R having a configuration different from that of FIG. In FIG. 7, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted below.

The refrigeration apparatus R shown in FIG. 7 includes a bypass circuit 82 and a solenoid valve 81 in addition to the configuration shown in FIG. One end of the bypass circuit 82 is connected to the refrigerant introduction pipe 22, and the other end of the bypass circuit 82 is connected to the suction port 64 of the auxiliary compressor 60.

Further, an electromagnetic valve 81 is provided in the middle of the bypass circuit 82. Opening and closing of the electromagnetic valve 81 is controlled by the control device 57. For example, the control device 57 stores in advance a data table indicating the relationship between the outside air temperature (high pressure side pressure HP) and the opening and closing of the electromagnetic valve 81, estimates the outside air temperature, and refers to the data table to Open / close of the valve 81 is set. A check valve may be provided instead of the solenoid valve 81.

For example, when the outside air temperature is about 32 degrees Celsius (high temperature environment, for example, summer), the control device 57 closes the solenoid valve 81 and drives the compressor 11 and the auxiliary compressor 60. Thereby, the refrigerant circulates as described in the operation example 1 or the operation example 2 described above.

On the other hand, for example, when the outside air temperature is 20 degrees Celsius or less (environment in a low temperature period, for example, in winter), the control device 57 opens the solenoid valve 81 and does not drive the compressor 11, and the auxiliary compressor 60 is driven. In addition, the control device 57 maximizes the valve opening degree of the electric expansion valve 33 and closes the electric expansion valve 43, the electric expansion valve 47, and the electric expansion valve 70.

Thereby, the refrigerant exiting the evaporator 41 flows into the bypass circuit 82 and is sucked into the suction port 64 of the auxiliary compressor 60. Then, the refrigerant compressed by the auxiliary compressor 60 is discharged from the discharge port 65 to the high pressure discharge pipe 27. Thereafter, the refrigerant flows in the order of the gas cooler 28, the electric expansion valve 33, the tank 36, the tank outlet pipe 37, the second flow path 29B of the split heat exchanger 29, the electric expansion valve 39, and the evaporator 41, and again the bypass circuit 82. Flows into.

FIG. 8 shows a PH diagram when the refrigerant flows through the bypass circuit 82. 8 are the same as those in FIGS. 2 and 3. As shown in FIG. 8, the refrigerant is compressed only in one stage by the auxiliary compressor 60.

As described above, according to the present configuration example, in the environment where the cooling load is reduced (low temperature period), the compressor 11 that is the two-stage compressor is not used, and only the auxiliary compressor 60 is used. Energy consumption can be reduced.

The bypass circuit 82 and the electromagnetic valve 81 (or check valve) may be added to the configuration shown in FIG.

(6) Another configuration example 3 of the refrigeration apparatus R
FIG. 9 is a refrigerant circuit diagram of a refrigeration apparatus R having a configuration different from that of FIG. Note that FIG. 9 is a simplified illustration of FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted below.

The refrigerating apparatus R shown in FIG. 9 includes a compressor 11a in addition to the configuration shown in FIG. The compressor 11 a is a two-stage compressor provided in parallel with the compressor 11 and has the same configuration as the compressor 11.

In the refrigeration apparatus R shown in FIG. 9, the refrigerant from the evaporator 41 is sucked into each of the compressor 11 and the compressor 11a. The refrigerant in which the refrigerant from the intercooler 24 and the refrigerant from the intermediate pressure return pipe 44 are mixed is sucked into the compressor 11 and the compressor 11a.

In FIG. 9, the electric expansion valve 39, the showcase 4, and the evaporator 41 are provided one by one. However, the electric expansion valve 39, the showcase 4, and the evaporator 41 are provided in a plurality. It is good. For example, one electric expansion valve 39, one showcase 4, and one evaporator 41 are set as one set, and the set is provided in parallel.

The compressor 11a may be added to the configuration shown in FIG.

(7) Another configuration example 4 of the refrigeration apparatus R
In the configuration shown in FIGS. 1, 5, 7, and 9, only one auxiliary compressor 60 is provided. However, a plurality of auxiliary compressors 60 may be provided. In that case, the refrigerant from the branch pipe 71 is sucked into each of the plurality of auxiliary compressors 60.

As described above, in this embodiment, the compressor 11 (compression means) having the first rotary compression element 14 and the second rotary compression element 16 driven by the same rotary shaft, the gas cooler 28, and the electric motor In the refrigeration apparatus R in which the refrigerant circuit 1 is configured by the expansion valve (main throttle means) 39 and the evaporator 41 and carbon dioxide refrigerant is used, an auxiliary compressor 60 (auxiliary compression means) provided separately from the compressor 11. And an electric expansion valve 33 (pressure adjusting throttle means) which is connected to the refrigerant circuit 1 downstream of the gas cooler 28 and upstream of the electric expansion valve 39 and adjusts the pressure of the refrigerant flowing out of the gas cooler 28; The tank 36 connected to the refrigerant circuit 1 downstream of the electric expansion valve 33 and upstream of the electric expansion valve 39, and the refrigerant circuit downstream of the tank 36 and upstream of the electric expansion valve 39 Set in 1 The split heat exchanger 29 having the first flow path 29A and the second flow path 29B, and the refrigerant flowing out of the gas pipe 42 (first pipe) provided at the first height of the tank 36 The electric expansion valve 43 (first auxiliary throttle means) for adjusting the pressure and the tank outlet pipe 37 (second pipe) provided at a position lower than the first height flow out of the split heat exchanger 29. An electric expansion valve 47 (second auxiliary throttle means) that adjusts the pressure of the first refrigerant of the refrigerant that has passed through the second flow path 29B and then diverted downstream of the second flow path 29B; After flowing out from the tank outlet pipe 37 and passing through the second flow path 29B of the split heat exchanger 29, the pressure of the second refrigerant out of the refrigerant divided on the downstream side of the second flow path 29B is adjusted. Electric expansion valve 70 (third auxiliary throttle means), electric expansion valve 70 and An auxiliary circuit 48 for sucking the refrigerant that has passed through the first flow path 29A of the split heat exchanger 29 into the auxiliary compressor 60 and an electromagnetic valve 74 or an electric expansion valve 75 (open / close valve) are provided and flowed out from the gas pipe 42. A bypass circuit 73 (first bypass circuit) for allowing the refrigerant to flow into the downstream side of the first flow path 29A of the split heat exchanger 29 in the auxiliary circuit 48, a refrigerant whose pressure is adjusted by the electric expansion valve 43, and electric expansion The return circuit 80 for sucking the refrigerant mixed with the refrigerant whose pressure is adjusted by the valve 47 into the intermediate pressure portion of the compressor 11, and the refrigerant flowing out of the tank 36 into the second flow path 29 </ b> B of the split heat exchanger 29. The refrigerant flows out and exchanges heat with the refrigerant flowing through the first flow path 29A of the split heat exchanger 29, and then the refrigerant out of the refrigerant divided downstream of the second flow path 29B flows into the electric expansion valve 39. The main circuit 38, the compressor 11, the auxiliary compressor 60, the electric expansion valve 39, the electric expansion valve 33, the electric expansion valve 43, the electric expansion valve 47, the electric expansion valve 70, and the electromagnetic valve 74 or the electric expansion 75. And a control device 57 (control means) for controlling the operation.

Thereby, in the case of using a carbon dioxide refrigerant, the refrigerant suction amount (exclusion volume) in the intermediate pressure part can be increased, and the intermediate pressure can be reduced even if the excluded volume ratio in the compressor 11 is determined. Can do. As a result, the specific enthalpy at the outlet of the tank 36 can be reduced, and the refrigerating capacity can be ensured.

In addition, the control device 57 closes the electric expansion valve 70 and opens the electromagnetic valve 74, opens the electric expansion valve 70, and closes the electromagnetic valve 74. The second setting is switched.

Also, the control device 57 performs the third setting for opening the electric expansion valve 70 and opening the electric expansion valve 75.

The refrigeration apparatus R further includes a bypass circuit 82 (second bypass circuit) that connects the auxiliary compressor 60 and the refrigerant introduction pipe 22 provided on the downstream side of the evaporator 41 and the upstream side of the compressor 11. In addition, the bypass circuit 82 is provided with a check valve or an electromagnetic valve 81 whose opening and closing is controlled by the control device 57.

This makes it possible to reduce energy consumption in an environment where the cooling load is reduced (low temperature period).

In the refrigeration apparatus R, the rotation speed of the auxiliary compressor 60 is variable.

Further, the refrigeration apparatus R includes a plurality of auxiliary compressors 60, and the refrigerant flowing through the auxiliary circuit 48 is sucked into the plurality of auxiliary compressors 60.

The refrigeration apparatus R includes a plurality of

compressors

11 and 11a provided in parallel with each other, and an intermediate pressure portion of the plurality of

compressors

11 and 11a is electrically operated with a refrigerant whose pressure is adjusted by an electric expansion valve 43. The refrigerant mixed with the refrigerant whose pressure is adjusted by the expansion valve 47 is sucked.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

The disclosure of the description, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2016-022124 filed on Feb. 8, 2016 is incorporated herein by reference.

The present invention is suitable for use in a refrigeration apparatus in which a refrigerant circuit is constituted by a compression means, a gas cooler, a main throttle means, and an evaporator.

R Refrigeration apparatus 1 Refrigerant circuit 3 Refrigerator unit 4 Showcase 6 Unit outlet 7

Unit inlet

8, 9 Refrigerant piping 11,

11a Compressor

12, 61 Sealed

container

13, 62 Electric element 14 First rotary compression element 16 Second Rotational compression element 17 Low stage side suction port 18 Low stage side discharge port 19 High stage side suction port 21 High stage side discharge port 22 Refrigerant introduction pipe 23 Intermediate pressure discharge pipe 24 Intercooler 26 Intermediate pressure suction pipe 27 High pressure discharge pipe 28 Gas cooler 29 Split heat exchanger 29A 1st flow path 29B 2nd flow path 31 Gas cooler blower 32 Gas cooler outlet piping 33 Electric expansion valve (throttle means for pressure adjustment)
34 Tank inlet piping 36 Tank 37 Tank outlet piping (third piping)
38 Main circuit 39 Electric expansion valve (Main throttle means)
41 Evaporator 42 Gas piping (first piping)
43 Electric expansion valve (first auxiliary circuit throttle means)
44 Intermediate pressure return piping 46 Liquid piping (second piping)
47 Electric expansion valve (second auxiliary circuit throttle means)
48 Auxiliary circuit 49 High pressure sensor 51 Low pressure sensor 52 Intermediate pressure sensor 53 Unit outlet sensor 57 Control device (control means)
60 Auxiliary compressor 63 Rotational compression element 64 Suction port 65 Discharge port 70 Electric expansion valve (third auxiliary circuit throttle means)
71 Branch piping (fourth piping)
72 Piping 73 Bypass circuit (first bypass circuit)
74, 81 Solenoid valve 75 Electric expansion valve 82 Bypass circuit (second bypass circuit)

Claims

A refrigerant circuit is constituted by a compression means having a first rotary compression element and a second rotary compression element driven by the same rotary shaft, a gas cooler, a main throttle means, and an evaporator, and carbon dioxide refrigerant is used. In the refrigeration apparatus
Auxiliary compression means provided separately from the compression means;
A pressure adjusting throttle means which is connected to the refrigerant circuit downstream of the gas cooler and upstream of the main throttle means and adjusts the pressure of the refrigerant flowing out of the gas cooler;
A tank connected to the refrigerant circuit downstream of the pressure adjusting throttle means and upstream of the main throttle means;
A split heat exchanger provided in the refrigerant circuit downstream of the tank and upstream of the main throttle means, and having a first flow path and a second flow path;
First auxiliary throttle means for adjusting the pressure of the refrigerant flowing out from the first pipe provided at the first height of the tank;
After flowing out of the second pipe provided at a position lower than the first height, passing through the second flow path of the split heat exchanger, it was divided on the downstream side of the second flow path. Second auxiliary throttle means for adjusting the pressure of the first refrigerant of the refrigerant;
The pressure of the second refrigerant out of the refrigerant that flows out from the second pipe, passes through the second flow path of the split heat exchanger, and is divided downstream of the second flow path is adjusted. Third auxiliary throttle means for
An auxiliary circuit that causes the auxiliary compression means to suck the refrigerant that has passed through the first flow path of the third auxiliary throttle means and the split heat exchanger;
A first bypass circuit that is provided with an on-off valve, and causes the refrigerant that has flowed out of the first pipe to flow into the downstream side of the first flow path of the split heat exchanger in the auxiliary circuit;
A return circuit for sucking into the intermediate pressure part of the compression means a refrigerant in which the refrigerant whose pressure is adjusted by the first auxiliary throttle means and the refrigerant whose pressure is adjusted by the second auxiliary throttle means;
The refrigerant that has flowed out of the tank flows through the second flow path of the split heat exchanger, and after heat exchange with the refrigerant flowing through the first flow path of the split heat exchanger, the second flow path A main circuit for flowing a third refrigerant out of the refrigerant diverted on the downstream side into the main throttle means;
The compression means, the auxiliary compression means, the main throttle means, the pressure adjusting throttle means, the first auxiliary throttle means, the second auxiliary throttle means, the third auxiliary throttle means, and the on-off valve Control means for controlling the operation of
Refrigeration equipment.
The on-off valve is a solenoid valve;
The control means includes
A first setting for closing the third auxiliary throttle means and opening the electromagnetic valve; and a third setting for opening the third auxiliary throttle means and closing the electromagnetic valve. Switch to the second setting,
The refrigeration apparatus according to claim 1.
The on-off valve is an electric expansion valve,
The control means includes
A third setting for opening the third auxiliary throttle means and opening the electric expansion valve;
The refrigeration apparatus according to claim 1.
A second bypass circuit connecting the auxiliary compression means and a pipe provided downstream of the evaporator and upstream of the compression means;
The second bypass circuit is provided with a check valve or an electromagnetic valve whose opening and closing is controlled by the control means.
The refrigeration apparatus according to claim 1.
The rotational speed of the auxiliary compression means is variable.
The refrigeration apparatus according to claim 1.
Apart from the auxiliary compression means, it comprises at least one auxiliary compression means,
The at least one auxiliary compression means includes
The refrigerant flowing through the auxiliary circuit is sucked in,
The refrigeration apparatus according to claim 1.
In addition to the compression means, at least one compression means is provided in parallel with the compression means,
In the intermediate pressure part of the at least one compression means,
The refrigerant mixed with the refrigerant whose pressure is adjusted by the first auxiliary throttle means and the refrigerant whose pressure is adjusted by the second auxiliary throttle means is sucked.
The refrigeration apparatus according to claim 1.