JP5794009B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus.

  2. Description of the Related Art Conventionally, a refrigeration apparatus is known that employs a refrigerant circuit that divides a refrigerant that has passed through a radiator into a refrigerant that goes to the evaporator side and a refrigerant that is injected again into the suction side of the compression mechanism.

  For example, in the refrigeration apparatus described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-263440), a technique is described in which the capacity and operation efficiency are improved by adjusting the amount of refrigerant to be injected (injection amount). .

  Some refrigeration apparatuses employ a centrifugal compressor equipped with an impeller as a compression mechanism, and some impellers are provided with slanted blades while spreading radially. When a centrifugal compressor employing an impeller having such a shape is used, the refrigerant flow on the intake side of the impeller is a degree according to the blade inclination angle and the number of rotations from the viewpoint of reducing loss. It is desirable to provide a swirling flow of

  Such a swirl flow is generated, for example, by adopting a form in which the axial direction of the other pipe is merged at an angle different from the axial direction of the one pipe in the pipe connecting portion where the refrigerant flows merge. It is possible.

  However, in the refrigeration apparatus described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-263440), only the adjustment of the injection amount to a desired flow rate is considered, and a swirling flow is applied to the intake refrigerant. It is not considered to cause it, and therefore the degree of swirl is not considered.

  For this reason, in the conventional refrigeration apparatus, even if a swirl flow is generated in the refrigerant sucked by the centrifugal compressor, the flow speed is determined by the flow rate of the adjusted desired injection amount and the flow rate of the refrigerant flow to be merged. Only a swirl flow is generated. Since the desired injection amount to be adjusted changes according to the operating conditions of the refrigeration apparatus, the swirling flow that occurs when the operating conditions change changes. Therefore, in the conventional refrigeration apparatus, the target swirl flow cannot be formed in a state adjusted to a desired injection amount.

  This invention is made | formed in view of the point mentioned above, The subject of this invention is providing the freezing apparatus which can form the target swirl flow, ensuring the injection amount of desired flow volume. It is in.

A refrigeration apparatus according to a first aspect of the present invention is a refrigeration apparatus that performs a multistage compression refrigeration cycle, wherein n compression mechanisms (n is a natural number of 2 or more), a radiator that dissipates heat of the refrigerant, and expansion. A mechanism, an evaporator for heating the refrigerant, an m-stage intermediate connecting pipe, an injection circuit, an economizer heat exchanger, an economizer expansion valve, and a control unit are provided. Each of the n compression mechanisms (n is a natural number of 2 or more) has an impeller provided with inclined blades. These n compression mechanisms (n is a natural number of 2 or more) are connected in series with each other. The radiator radiates the heat of the refrigerant. The m-stage intermediate connecting pipe connects the discharge side of the m-th stage compression mechanism (m is a natural number less than n) and the suction side of the m + 1-th stage compression mechanism. A total of n-1 m-stage intermediate connecting pipes are provided. The injection circuit branches a part of the refrigerant flow from the radiator toward the expansion mechanism and joins it to the m-stage intermediate connecting pipe. The economizer heat exchanger exchanges heat between the refrigerant from the radiator toward the expansion mechanism and the refrigerant flowing through the injection circuit. The economizer expansion valve is provided in the middle of the injection circuit and upstream of the portion where heat is exchanged in the economizer heat exchanger. The injection circuit has an upstream channel, a downstream channel, and an adjustment mechanism. The upstream flow path guides a part of the refrigerant that has passed through the economizer expansion valve to the upstream confluence of the m-stage intermediate connecting pipe. The downstream flow path is located downstream of the upstream junction of the m-stage intermediate connecting pipe so that the other part of the refrigerant that has passed through the economizer expansion valve is swirled to the suction refrigerant of the m + 1-stage compression mechanism. Guide to the downstream junction. The adjusting mechanism adjusts the refrigerant flow rate ratio between the upstream channel and the downstream channel. The control unit adjusts the refrigerant flow ratio by controlling the adjustment mechanism while controlling the valve opening degree of the economizer expansion valve so that the superheat degree of the refrigerant discharged from the m + 1 stage compression mechanism becomes the target superheat degree. Thus, the swirl flow generated in the refrigerant sucked by the m + 1 stage compression mechanism is adjusted.

  It is not necessary to provide n-1 injection circuits so as to correspond to all of n-1 m-stage intermediate connection pipes. For example, n-1 of all m-stage intermediate connection pipes are not required. You may provide only in the specific intermediate | middle connecting pipe of a number smaller than a piece.

  In this refrigeration apparatus, the refrigerant flowing through the injection circuit is divided into a refrigerant flowing through the upstream flow path and a refrigerant flowing through the downstream flow path. And the ratio of the refrigerant | coolant flow volume which flows through these upstream flow paths and downstream flow paths is adjusted when a control part operates an adjustment mechanism. As a result, the adjustment mechanism adjusts the flow rate at which the flow rate necessary for forming the desired swirl flow is ensured in the downstream flow channel, and the upstream flow channel is determined from the capacity and the operation efficiency. Further, the remaining flow rate obtained by subtracting the amount to be flowed to the downstream channel from the injection amount can be flowed.

  This makes it possible to form a target swirl flow while ensuring an injection amount of a desired flow rate.

A refrigeration apparatus according to a second aspect of the present invention is the refrigeration apparatus according to the first aspect, wherein the control unit controls the pressure of the refrigerant flowing through the outlet of the economizer heat exchanger of the injection circuit and the suction refrigerant of the m + 1 stage compression mechanism. The adjustment mechanism is controlled so that the flow rate ratio is determined in advance according to the pressure differential pressure.

  In this refrigeration system, the desired swirling flow can be formed by a simple operation by grasping the pressure of the refrigerant flowing through the outlet of the economizer heat exchanger and the pressure of the refrigerant sucked by the m + 1 stage compression mechanism. Is possible.

  In the refrigeration apparatus according to the third aspect of the present invention, in the refrigeration apparatus according to the first aspect or the second aspect, the downstream flow path has a throat shape.

  In this refrigeration apparatus, the flow rate of the refrigerant that has passed through the throat-shaped portion can be increased because the downstream-side channel has the throat shape. For this reason, even if there is little refrigerant | coolant flow volume which flows through an injection circuit, it becomes easy to form the target swirl | vortex flow.

  In the refrigeration apparatus according to the first aspect of the present invention, it is possible to form a target swirl flow while ensuring an injection amount of a desired flow rate.

  In the refrigeration apparatus according to the second aspect of the present invention, it is possible to form a target swirl flow with a simple operation.

  In the refrigeration apparatus according to the third aspect of the present invention, even if the flow rate of the refrigerant flowing through the injection circuit is small, it becomes easy to form the target swirl flow.

It is a schematic refrigerant circuit diagram of a refrigeration apparatus. It is a Mollier diagram corresponding to a freezing apparatus. It is a block diagram which shows a control structure. It is a schematic sectional drawing of a compression mechanism. It is a schematic perspective view which shows the external appearance of an impeller. It is a schematic perspective view of the vicinity of a merge part. It is a driving | operation control flowchart of a heat pump apparatus. It is the schematic in the front view of the impeller of the structural example of multi-site confluence | merging which concerns on other embodiment (6-1).

  Hereinafter, an embodiment of a heat pump apparatus employing a centrifugal compressor according to the present invention will be described with reference to the drawings.

(1) Overall Configuration of Heat Pump Device 1 FIG. 1 is a schematic configuration diagram of a heat pump device 1 in which a multistage centrifugal compressor 2 which is an example of a centrifugal compressor according to the present invention is employed. In FIG. 1, for both the first four-way switching valve 4a and the second four-way switching valve 4b, the solid line connection state is described as the cooling operation state, and the dotted line connection state is described as the heating operation state. In addition, the arrow in a refrigerant circuit has shown the direction through which the refrigerant | coolant flows in a cooling operation state. FIG. 2 shows a Mollier diagram when the refrigeration cycle is performed in the cooling circuit.

  In addition, the following refrigerant | coolant flows are demonstrated as a flow direction at the time of air_conditionaing | cooling operation.

  The heat pump device 1 is a device that generates air conditioning and cold / hot water by a vapor compression refrigeration cycle. The heat pump apparatus 1 mainly includes a multistage centrifugal compressor 2, a first four-way switching valve 4a and a second four-way switching valve 4b, a heat source side heat exchanger 3, a first economizer circuit 60, a second economizer circuit 70, a third The economizer circuit 80, the expansion mechanism 8, and the use side heat exchanger 5 are provided, and a refrigerant circuit is configured by connecting these devices. Here, carbon dioxide is used as the refrigerant. The refrigerant circuit includes a main refrigerant circuit, a first economizer circuit 60, a second economizer circuit 70, and a third economizer circuit 80.

  In the multistage centrifugal compressor 2, in the present embodiment, the first compression mechanism 10, the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40 are connected in series to compress the refrigerant stepwise. It is configured. A suction pipe 6 is connected to the suction side (point A in FIG. 1) of the first compression mechanism 10 so that the refrigerant flowing out from the use side heat exchanger 5 can be sucked. The discharge side (point B in FIG. 1) of the first compression mechanism 10 and the suction side (point C in FIG. 1) of the second compression mechanism 20 are connected by a first intermediate connecting pipe 18. The discharge side (point D in FIG. 1) of the second compression mechanism 20 and the suction side (point E in FIG. 1) of the third compression mechanism 30 are connected by a second intermediate connecting pipe 28. The discharge side (point F in FIG. 1) of the third compression mechanism 30 and the suction side (point G in FIG. 1) of the fourth compression mechanism 40 are connected by a third intermediate connecting pipe 38. A discharge pipe 7 connected to the first four-way selector valve 4a is connected to the discharge side (point H in FIG. 1) of the fourth compression mechanism 40.

  The first four-way switching valve 4 a is connected between the discharge pipe 7 extending from the discharge side of the fourth compression mechanism 40 of the multistage centrifugal compressor 2 and the heat source side heat exchanger 3. The second four-way switching valve 4b is connected to the heat source side heat exchanger 3 on the side opposite to the first four-way switching valve 4a side, and is connected to the expansion mechanism 8 and the use side heat exchange. It has a port connected to the device 5. The first four-way switching valve 4a and the second four-way switching valve 4b perform switching between the cooling operation state and the heating operation state by switching the refrigerant flow in the refrigerant circuit. During the cooling operation, the heat-source-side heat exchanger 3 functions as a refrigerant radiator, and the user-side heat exchanger 5 functions as a refrigerant evaporator. During the heating operation, the heat source side heat exchanger 3 is caused to function as a refrigerant evaporator while the use side heat exchanger 5 is allowed to function as a refrigerant radiator. In addition, when the heat source side heat exchanger 3 and the use side heat exchanger 5 function as refrigerant radiators, they heat the air in the air-conditioning target space and / or heat a fluid such as water. In addition, when the heat source side heat exchanger 3 and the use side heat exchanger 5 function as a refrigerant evaporator, the air in the air-conditioning target space is cooled and / or the fluid such as water is cooled.

  The expansion mechanism 8 is a mechanism that lowers the pressure of the refrigerant that passes therethrough.

  The third economizer circuit 80, the second economizer circuit 70, and the first economizer circuit 60 are provided so as to branch from the main refrigerant circuit between the second four-way switching valve 4b and the expansion mechanism 8 in this order. .

  The third economizer circuit 80 includes a third injection pipe 83, a third expansion valve 82, a third economizer heat exchanger 81, a third flow rate adjustment valve 86, a third upstream flow path 84, and a third downstream flow path. 85. The third economizer heat exchanger 81 is provided on the expansion mechanism 8 side with respect to the branch point I located on the downstream side of the second four-way switching valve 4 b, and is a third expansion valve 82 that flows through the third injection pipe 83. Heat exchange is performed between the decompressed refrigerant and the refrigerant flowing through the main refrigerant circuit. The third injection pipe 83 branches from the branch point I, passes through the third expansion valve 82, passes through the third economizer heat exchanger 81, and then extends to the third flow rate control valve 86. In the third flow rate control valve 86, the third injection pipe 83 is branched into a third upstream flow path 84 and a third downstream flow path 85, and the amount of refrigerant flowing to the third upstream flow path 84 side and the 3 It is possible to adjust the amount of refrigerant flowing to the downstream channel 85 side. The third upstream flow path 84 and the third downstream flow path 85 are both connected to the third intermediate connecting pipe 38 at the end opposite to the third flow rate control valve 86 side. The connection point 38a between the third upstream flow path 84 and the third intermediate connection pipe 38 is located in the third intermediate connection pipe 38 more than the junction 38b between the third downstream flow path 85 and the third intermediate connection pipe 38. It is provided upstream. The third downstream flow path 85 is connected to a portion of the third intermediate connecting pipe 38 immediately before the suction port of the fourth compression mechanism 40. The third downstream flow path 85 has a flow direction so that a swirling flow can be given to the refrigerant flow in which the refrigerant flowing through the third upstream flow path 84 and the refrigerant flowing through the third intermediate connecting pipe 38 merge. The third intermediate connecting pipe 38 is connected substantially perpendicularly to a position off the center. Thereby, a swirl flow can be generated in the suction refrigerant of the fourth compression mechanism 40.

  The second economizer circuit 70 is the same as the third economizer circuit 80, and includes a second injection pipe 73, a second expansion valve 72, a second economizer heat exchanger 71, a second flow rate adjustment valve 76, a second upstream side flow path. 74 and a second downstream flow path 75. The second economizer heat exchanger 71 is provided closer to the expansion mechanism 8 than the branch point J where the refrigerant flowing out from the third economizer circuit 80 in the main refrigerant circuit branches, and the second expansion flowing through the second injection pipe 73. Heat exchange is performed between the refrigerant decompressed by the valve 72 and the refrigerant flowing through the main refrigerant circuit. The second injection pipe 73 branches from the branch point J, passes through the second expansion valve 72, passes through the second economizer heat exchanger 71, and then extends to the second flow rate adjustment valve 76. In the second flow control valve 76, the second injection pipe 73 is branched into a second upstream flow path 74 and a second downstream flow path 75, and the amount of refrigerant flowing to the second upstream flow path 74 side and the second 2 The amount of refrigerant flowing to the downstream channel 75 side can be adjusted. The second upstream flow path 74 and the second downstream flow path 75 are both connected to the second intermediate connecting pipe 28 at the end opposite to the second flow rate adjustment valve 76 side. The connection point 28a between the second upstream flow path 74 and the second intermediate connection pipe 28 is located in the second intermediate connection pipe 28 more than the junction 28b between the second downstream flow path 75 and the second intermediate connection pipe 28. It is provided upstream. The second downstream flow path 75 is connected to a portion of the second intermediate connecting pipe 28 immediately before the suction port of the third compression mechanism 30. The second downstream flow path 75 has a flow direction so that a swirl flow can be given to the refrigerant flow in which the refrigerant flowing through the second upstream flow path 74 and the refrigerant flowing through the second intermediate connecting pipe 28 merge. The second intermediate connecting pipe 28 is connected substantially perpendicularly to a position away from the center. As a result, a swirling flow can be generated in the suction refrigerant of the third compression mechanism 30.

  The first economizer circuit 60 is the same as the third economizer circuit 80 and the second economizer circuit 70, and includes a first injection pipe 63, a first expansion valve 62, a first economizer heat exchanger 61, a first flow control valve 66, It has a first upstream channel 64 and a first downstream channel 65. The first economizer heat exchanger 61 is provided closer to the expansion mechanism 8 than the branch point K where the refrigerant flowing out from the second economizer circuit 70 in the main refrigerant circuit branches, and the first expansion flowing through the first injection pipe 63. Heat exchange is performed between the refrigerant decompressed by the valve 62 and the refrigerant flowing through the main refrigerant circuit. The first injection pipe 63 branches from the branch point K, passes through the first expansion valve 62, passes through the first economizer heat exchanger 61, and then extends to the first flow rate adjustment valve 66. In the first flow control valve 66, the first injection pipe 63 is branched into a first upstream flow path 64 and a first downstream flow path 65, and the amount of refrigerant flowing to the first upstream flow path 64 side and the first The amount of refrigerant flowing to the downstream side flow path 65 side can be adjusted. The first upstream flow path 64 and the first downstream flow path 65 are both connected to the first intermediate connecting pipe 18 at the end opposite to the first flow rate adjustment valve 66 side. The joining point 18a between the first upstream flow path 64 and the first intermediate connecting pipe 18 is more in the first intermediate connecting pipe 18 than the joining point 18b between the first downstream flow path 65 and the first intermediate connecting pipe 18. It is provided upstream. The first downstream flow path 65 is connected to a portion of the first intermediate connecting pipe 18 immediately before the suction port of the second compression mechanism 20. The first downstream flow path 65 has a flow direction so that a swirling flow can be given to the refrigerant flow in which the refrigerant flowing through the first upstream flow path 64 and the refrigerant flowing through the first intermediate connecting pipe 18 merge. The first intermediate connecting pipe 18 is connected substantially perpendicularly to a position off the center. As a result, a swirling flow can be generated in the suction refrigerant of the second compression mechanism 20.

  The cooling pipe 9a is a pipe that branches the low-pressure refrigerant that has been depressurized by the expansion mechanism 8 from the refrigerant circuit and leads to the internal space of the motor casing 51 described later (see FIG. 2). The cooling pipe 9 b is a pipe that guides the low-pressure refrigerant that has passed through the internal space of the motor casing 51 to the suction pipe 6. Thereby, the pressure in the internal space of the motor casing 51 is a low pressure in the refrigeration cycle, and the rotor 53 and the stator 54 are cooled by the low-pressure refrigerant.

  Thus, the heat pump apparatus 1 is an apparatus that generates air conditioning and cold / hot water by a vapor compression refrigeration cycle that uses carbon dioxide as a refrigerant, and uses a multistage centrifugal compressor 2 as a compressor. For this reason, the operating pressure of the refrigerant is higher than when using chlorofluorocarbon or the like as the refrigerant. For example, when R134a which is a kind of Freon is used as the refrigerant, the low pressure of the refrigeration cycle is about 0.29 MPa (evaporation temperature 0 ° C.), and the high pressure of the refrigeration cycle is about 0.77 MPa (condensation temperature 30 ° C.). It is. On the other hand, when carbon dioxide is used as the refrigerant, the low pressure of the refrigeration cycle is about 3.5 MPa (evaporation temperature 0 ° C.), the high pressure of the refrigeration cycle is about 7.2 MPa (condensation temperature 30 ° C.), etc. Become.

  In the heat pump device 1, when the refrigeration cycle is performed in the cooling operation state when the connection state of the first four-way switching valve 4a and the second four-way switching valve 4b is indicated by the points A to L in FIG. The state of the refrigerant flowing through the portion is the state indicated by the corresponding points A to L on the Mollier diagram of FIG.

  The heat pump device 1 is controlled by a control device 90 as shown in the control block diagram of FIG. The control device 90 is connected to the input device 95 and controls the operation of the heat pump device 1 so that the input device 95 follows the setting received from the user. The control device 90 includes a control CPU 91 that performs various arithmetic processes, a control memory 92 that stores various data for performing control, and the like. In the control memory 92, control information for the first flow rate adjusting valve 66, which is predetermined in accordance with the operation status, in order to generate a desired swirling flow in the refrigerant sucked in the second compression mechanism 20 described later, third compression In order to generate a desired swirling flow in the refrigerant sucked by the mechanism 30, control information for the second flow rate control valve 76 that is predetermined according to the operating conditions, and a desired swirling flow is generated in the refrigerant sucked by the fourth compression mechanism 40. Therefore, control information of the third flow rate control valve 86 that is predetermined according to the operating situation is stored. Specifically, the relationship between the flow rate required in the first downstream flow path 65 with respect to the differential pressure between the pressure of the refrigerant that has passed through the first economizer heat exchanger 61 and the suction pressure of the second compression mechanism 20, The relationship between the flow rate required in the first downstream-side flow path 65 with respect to the differential pressure between the refrigerant pressure that has passed through the economizer heat exchanger 71 and the suction pressure of the third compression mechanism 30, and the fourth economizer heat exchanger 81 The relationship of the flow rate required in the first downstream flow path 65 with respect to the differential pressure between the refrigerant pressure that has passed through and the suction pressure of the fourth compression mechanism 40 is stored in advance as flow rate relationship data for each operating condition. .

  In the input device 95, an input CPU 96 that performs various arithmetic processes for receiving input from the user and transmitting the received input data to the control device 90, and an input for storing various setting data that has received the input, etc. Memory 97 is provided. This setting data is also stored in the control memory 92.

  In the heat pump device 1, the pressure and temperature of the refrigerant flowing through the suction pipe 6, the pressure and temperature of the refrigerant flowing immediately before the second compression mechanism 20 of the first intermediate connection pipe 18, and the third compression of the second intermediate connection pipe 28 are included. The pressure and temperature of the refrigerant flowing just before the mechanism 30, the pressure and temperature of the refrigerant flowing just before the fourth compression mechanism 40 of the third intermediate connecting pipe 38, and the first four-way switching valve 4a discharged from the fourth compression mechanism 40 Sensors are provided for respectively grasping the pressure and temperature of the refrigerant toward the. Furthermore, a sensor is also provided for grasping the pressure and temperature of the refrigerant flowing through the injection pipes 63, 73, 83 that have passed through the economizer heat exchangers 61, 71, 81. As shown in the control block diagram of FIG. 3, the data obtained from these sensors is obtained by the control device 90 by the first compression mechanism 10, the second compression mechanism 20, the third compression mechanism 30, the fourth compression mechanism 40, First four-way switching valve 4a, second four-way switching valve 4b, expansion mechanism 8, first expansion valve 62, second expansion valve 72, third expansion valve 82, first flow control valve 66, second flow control valve 76, used for controlling the third flow rate adjusting valve 86 and the like.

(2) Configuration of Multistage Centrifugal Compressor FIG. 4 is a schematic sectional view of the multistage centrifugal compressor 2. FIG. 5 is a schematic external perspective view showing the impeller of the second compression mechanism 20. FIG. 6 is a schematic diagram showing a merged shape that generates a swirling flow.

  Here, the rotation center of the impeller provided in each compression mechanism is O, the rotation axis is OO, and the direction along the rotation axis OO is the axial direction or the front-rear direction. The direction approaching the shaft is defined as the radially inner side (inner side in the rotational radius direction), and the direction away from the shaft is defined as the radially outer side (outer side in the rotational radius direction).

  The multistage centrifugal compressor 2 mainly includes a motor 50, a first compression mechanism 10, a second compression mechanism 20, a third compression mechanism 30, and a fourth compression mechanism 40.

(2-1) Motor 50
The motor 50 is a motor that drives the first compression mechanism 10 to the fourth compression mechanism 40, and mainly includes a motor casing 51, a rotating shaft 52, a rotor 53, and a stator 54.

  Inside the motor casing 51, a space for accommodating the rotating shaft 52, the rotor 53, and the stator 54 is formed.

  The rotary shaft 52 is rotatably supported by a first radial bearing 55 and a second radial bearing 56 that are fixed to the motor casing 51. One end (left end in FIG. 4) of the rotation shaft 52 in the axial direction protrudes toward the first compression mechanism 10 side. The other axial end of the rotating shaft 52 (the right end in FIG. 4) protrudes toward the third compression mechanism 30 side. The vicinity of the center of the rotating shaft 52 in the axial direction is slidably supported by a thrust bearing 57 fixed to the motor casing 51.

  The rotor 53 is pivotally supported on the rotary shaft 52 so as to rotate integrally with the rotary shaft 52 between the first radial bearing 55 and the second radial bearing 56 in the axial direction.

  The stator 54 is provided so as to surround the outer periphery of the rotor 53 and is supported by the motor casing 51 so as not to rotate.

(2-2) First compression mechanism 10 to fourth compression mechanism 40
As described above, the first compression mechanism 10, the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40 are connected to each other in series, and are centrifugal compression mechanisms that compress refrigerant in stages. .

  The first compression mechanism 10 mainly has a compression mechanism casing 12 and an impeller 11. Similarly, the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40 mainly include a compression mechanism casing 22 and an impeller 21, a compression mechanism casing 32 and an impeller 31, a compression mechanism casing 42, and an impeller 41, respectively. doing.

  The arrangement structure relationship between the compression mechanism casing 22 and the impeller 21 includes the arrangement structure relationship between the other compression mechanism casing 12 and the impeller 11, the arrangement structure relationship between the compression mechanism casing 32 and the impeller 31, and the compression mechanism casing 42 and the impeller 41. Therefore, the second compression mechanism 20 will be mainly described below.

(Compression mechanism casing 22)
The compression mechanism casing 22 is mainly formed with a suction port 22a and a shroud housing 22c.

  The suction port 22 a is open toward one axial end (left end in FIG. 4) of the compression mechanism casing 22, and is connected to the first intermediate connecting pipe 18 extending from the discharge side of the first compression mechanism 10. Here, the velocity energy of the refrigerant discharged from the first compression mechanism 10 toward the first intermediate connecting pipe 18 is converted into pressure energy in the diffuser to become a high-pressure refrigerant in the second compression mechanism 20. Inhaled. In addition, the 2nd intermediate | middle connection pipe | tube 28 is connected to the discharge side of the 2nd compression mechanism 20, and a diffuser is provided similarly.

  As shown in FIG. 4, the shroud housing 22 c rotatably accommodates the impeller 21 on the back side of the suction port 22 a, and a blade facing wall 22 b that covers the front of the impeller 21 from the outside in the radial direction and around the front. Is formed. The blade-facing wall 22b bulges toward the rear side and radially inward, and gently connects the suction port 22a and the downstream end of the second intermediate connecting pipe 28 around the rotation axis. An annular bulging surface.

(Impeller 21)
As shown in FIG. 5, the impeller 21 mainly includes a hub 211 and a plurality of blades 212 and 213 arranged on the front side of the hub 211 and radially outside, and extends in the front-rear direction of the hub 211. The rotating shaft 52 rotates around the axis.

  The hub 211 has a substantially conical shape whose diameter increases from the front toward the rear, and is supported by the rotary shaft 52 so as to rotate integrally with the rotary shaft 52. In addition, it is preferable that this hub 211 is hollow inside a shaft peripheral part and an outer edge part from a viewpoint of weight reduction.

  The rear surface of the hub 211 is formed with a hub rear surface 211d, which is a circular flat surface extending in the radial direction, and is opposed to the rear wall surface of the shroud housing 22c. The front side of the hub 211 extends in the radial direction, and a hub front surface 211a that is a circular plane having a smaller radius than the hub back surface 211d is formed, and faces the suction side. The hub 211 has an outer end in the radial direction that has a common axial direction and a central axis, and is formed with a hub cylindrical surface 211c having a radius equal to that of the hub rear surface 211d, and is opposed to the outer peripheral wall of the shroud housing 22c. doing. The hub 211 is gently recessed in the front and radially outer side toward the rear and radially inward, and gently extends from the radially outer peripheral edge of the hub front surface 211a to the front edge of the hub cylindrical surface 211c. A radial curved surface 211b is formed. Note that the shortest distance between the diameter-enlarged curved surface 211b of the impeller 21 and the blade facing wall 22b of the shroud housing 22c is the longest in the front (suction side), and becomes shorter as it proceeds in the refrigerant flow direction. It is formed to be the shortest on the (discharge side).

  The large-diameter curved surface 211b of the impeller 21 is provided with large blades 212 and small blades 213 arranged alternately in the circumferential direction so that the surfaces are substantially equidistant. Both the large blade 212 and the small blade 213 extend from the diameter-expanded curved surface 211b of the impeller 21 to the vicinity of the blade-facing wall 22b of the shroud housing 22c. The large blade 212 has a facing surface 212b that faces the blade facing wall 22b. Similarly, the small blade 213 has a facing surface 213b facing the blade facing wall 22b. Further, the large blade 212 has a discharge side surface 212c whose normal line is directed in the extending direction of the second intermediate connecting pipe 28 at the radially outer end. Similarly, the small blade 213 has a discharge side surface 213c whose normal line faces the direction in which the second intermediate connecting pipe 28 extends at the radially outer end. Further, both the large blade 212 and the small blade 213 extend spirally so as to be left-handed when viewed from the front. That is, the large blades 212 and the small blades 213 extend so as to turn to the left while expanding in the radial direction from the hub front surface 211a side toward the back surface side.

  Furthermore, the longitudinal direction of the front side end portions of the large blade 212 and the small blade 213 and the longitudinal direction of the radially outer end portion are in a twisted relationship with each other. The twisted shape is such that the side opposite to the base of the large blade 212 and the small blade 213 (the blade facing wall 22b side of the shroud housing 22c) turns counterclockwise as it goes from the hub front surface 211a side to the back surface side. Is formed.

  Each large blade 212 extends from the front end of the enlarged diameter curved surface 211b of the impeller 21 to a position where the radially outer end is in common with the radially outer end of the back surface.

  On the other hand, each small blade 213 is disposed between each large blade 212, and the radially outer end portion is the rear surface from the middle position between the hub front surface 211a and the rear surface in the axial direction toward the rear. It extends to a position common to the radially outer end of.

  When the impeller 21 is driven by the motor 50 and rotates rightward in the front view (rotational direction R indicated by an arrow in FIG. 5), the carbon dioxide refrigerant is sucked from the first intermediate connecting pipe 18 and compressed. Then, the pressure is discharged toward the second intermediate connecting pipe 28.

  At this time, the portions on the front side and radially outside of the large blades 212 and the small blades 213 move along the inside of the blade facing wall 22b of the shroud housing 22c as the impeller 21 rotates. As a result, the carbon dioxide refrigerant is discharged in an increased flow rate, and the speed energy is converted into pressure energy in the diffuser to become a high-pressure refrigerant.

  Note that the shape of the impeller 21 that is swirling while the blades of the impeller 21 are tilted has the control data corresponding to the operation state in the control memory 92 in order to generate an efficient swirling flow with little pressure loss in the sucked refrigerant. Stored in advance.

  As described above, the arrangement structure relationship between the second compression mechanism casing 22 and the impeller 21 of the second compression mechanism 20 has been described. These relationships include the impeller 11, the suction port 12a, the blade facing wall 12b of the first compression mechanism 10, and the like. The relationship between the shroud housing 12c, the relationship between the impeller 31, the suction port 32a, the blade facing wall 32b, and the shroud housing 32c of the third compression mechanism 30, the impeller 41, the suction port 42a, and the blade facing wall 42b of the fourth compression mechanism 40. Since it is the same as that of the shroud housing 42c, description is abbreviate | omitted.

(3) Swirling flow adjustment operation by the first flow rate adjustment valve 66, the second flow rate adjustment valve 76, and the third flow rate adjustment valve 86 The control device 90 stores in advance in the control memory 92 the data obtained from various sensors. The second compression mechanism 20 and the third compression mechanism 30 are adjusted by adjusting respective flow ratios in the first flow rate adjustment valve 66, the second flow rate adjustment valve 76, and the third flow rate adjustment valve 86 based on the stored data. The desired amount of swirl is generated on each suction side of the fourth compression mechanism 40.

  Hereinafter, it demonstrates along the control flowchart of the heat pump apparatus 1 containing adjustment control of a flow rate ratio shown in FIG.

  First, in step S10, the control device 90 refers to the setting data stored in the control memory 92, reads out the target setting temperature, and cools so as to reduce the difference from the temperature of the medium to be heated or cooled. The capacity (Qc0) or the heating capacity (Qh0) is set.

  Next, in step S20, the control device 90 sets the temperature and pressure of the suction refrigerant and the temperature and pressure of the discharge refrigerant to the first compression mechanism 10, the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40. Understand each of the. Further, the control device 90 grasps the temperature and pressure of the refrigerant flowing through the outlet of the heat source side heat exchanger 3 or the use side heat exchanger 5. With reference to the information obtained in this way and the data relating to the Mollier diagram stored in advance in the control memory 92 or the data of the approximate expression for calculating the enthalpy from the value obtained by each sensor, FIG. The enthalpy (hA to hL) is calculated for the refrigerant that passes through each of the points A to L in the refrigerant circuit.

  In step S30, the control device 90 refers to each enthalpy value obtained in step S20 so that the cooling capacity (Qc0) or the heating capacity (Qh0) set in step S10 is achieved. The mass flow rate (mass flow rate (Ge) of the refrigerant flowing through the outlet of the evaporator during cooling operation, and mass flow rate (Ggc) of the refrigerant flowing through the outlet of the radiator during heating operation) are determined. In the present embodiment, for the cooling operation, the mass flow rate (Ge) is obtained from the following relational expression.

Mass flow rate (Ge) = cooling capacity (Qc0) / (enthalpy of suction refrigerant of first compression mechanism 10 (hA) −enthalpy of refrigerant passing through inlet of heat exchanger 5 on use side after passing through expansion mechanism 8 (hL) ))
In the present embodiment, the mass flow rate (Ggc) is obtained from the following relational expression during the heating operation.

Mass flow rate (Ggc) = heating capacity (Qc0) / (enthalpy of refrigerant discharged from fourth compression mechanism 40 (hH) −enthalpy of refrigerant passing through branch point I (hI))
In step S40, the control device 90 performs the impeller 11 of the first compression mechanism 10, the impeller 21 of the second compression mechanism 20, the impeller 31 of the third compression mechanism 30, and the fourth compression based on the mass flow rate obtained in step S30. The rotation speed (rpm) of the impeller 41 of the mechanism 40 is specified, and control is performed so that the specified rotation speed is executed.

  Note that the control device 90 causes the superheat degree of the refrigerant discharged from the second compression mechanism 20 to be a target superheat degree in a state where the compression mechanisms 10, 20, 30, and 40 are operated at the respective rotation speeds. The second expansion valve of the second economizer circuit 70 controls the opening degree of the first expansion valve 62 of the first economizer circuit 60 so that the superheat degree of the refrigerant discharged from the third compression mechanism 30 becomes the target superheat degree. The valve opening of the third expansion valve 82 of the third economizer circuit 80 is controlled so that the degree of superheat of the refrigerant discharged from the fourth compression mechanism 40 becomes the target degree of superheat. Thus, the control device 90 controls the mass flow rate of the refrigerant flowing through the first injection pipe 63 so that the superheat degree of the refrigerant discharged from the second compression mechanism 20 becomes the target superheat degree, and the third compression The mass flow rate of the refrigerant flowing through the second injection pipe 73 is controlled so that the superheat degree of the refrigerant discharged from the mechanism 30 becomes the target superheat degree, and the superheat degree of the refrigerant discharged from the fourth compression mechanism 40 is targeted. Therefore, the mass flow rate of the refrigerant flowing through the third injection pipe 83 is controlled so as to achieve the degree of superheat. Note that the target superheat degree of the second compression mechanism 20, the target superheat degree of the third compression mechanism 30, and the target superheat degree of the fourth compression mechanism 40 are values that can make the operation efficiency of the refrigeration cycle good. A value corresponding to the mass flow rate is stored in advance in the control memory 92.

  In step S50, the control device 90 performs the operation control that achieves the required capability as described above, and the pressure of the refrigerant that has passed through the first economizer heat exchanger 61 and the second compression mechanism 20. , The refrigerant pressure passing through the second economizer heat exchanger 71 and the suction pressure of the third compression mechanism 30, the refrigerant pressure passing through the fourth economizer heat exchanger 81 and the suction pressure of the fourth compression mechanism 40. , Grasp from each sensor. Thereafter, based on the flow rate ratio relation data stored in the control memory 92, the control device 90 corresponds to each differential pressure, the first downstream channel 65, the second downstream channel 75, the third downstream. Each mass flow rate required in the side channel 85 is specified. The control device 90 controls the first flow rate adjustment valve 66 so that the necessary mass flow rate specified in the first downstream flow path 65 is realized, and the required mass specified in the second downstream flow path 75. The second flow rate adjustment valve 76 is controlled so that the flow rate is realized, and the third flow rate adjustment valve 86 is controlled so that the necessary mass flow rate specified in the third downstream flow path 85 is realized.

  In addition, from the mass flow rate of the refrigerant | coolant which flows into the 1st upstream flow path 64 from the 1st injection pipe 63 determined by the valve opening degree control of the 1st expansion valve 62 of the 1st economizer circuit 60 in step S40, step S50 is carried out. The remaining mass flow rate refrigerant obtained by subtracting the mass flow rate required in the first downstream-side flow path 65 determined in step 1 flows. Similarly, from the mass flow rate of the refrigerant flowing through the second injection pipe 73 determined by the valve opening degree control of the second expansion valve 72 of the second economizer circuit 70 in step S40, the second upstream flow path 74 is stepped. The refrigerant having the remaining mass flow rate obtained by subtracting the mass flow rate required in the second downstream flow path 75 determined in S50 flows, and the third economizer circuit in step S40 flows in the third upstream flow path 84. The mass flow rate required in the third downstream flow path 85 determined in step S50 is subtracted from the mass flow rate of the refrigerant flowing through the third injection pipe 83 determined by the opening degree control of the third expansion valve 82 of 80. The remaining mass flow rate of refrigerant will flow.

(4) Formation of Swirling Flow As shown in the schematic diagram of FIG. 6, the refrigerant sucked by the second compression mechanism 20 flows through the refrigerant flow F <b> 1 flowing through the first intermediate connecting pipe 18 and the first downstream flow path 65. A swirling flow F3 (F1 + F2) is generated by combining the refrigerant flow F2.

  Specifically, the suction side of the second compression mechanism 20 of the first intermediate connecting pipe 18 has a shape extending in the same direction as the rotation axis direction of the impeller 21 of the second compression mechanism 20. A refrigerant flow F1 is generated along the rotation axis direction. The first downstream-side flow path 65 is a portion of the first intermediate connecting pipe 18 immediately before the suction port 22a of the second compression mechanism 20 at a position deviated from the central axis direction of the first intermediate connecting pipe 18. It is connected so that its own central axis is substantially perpendicular to the central axis direction of the intermediate connecting pipe 18. In the first downstream flow path 65, a refrigerant flow F2 is generated that flows in a direction that is twisted with respect to the rotation axis direction of the impeller 21. The refrigerant flow F1 and the refrigerant flow F2 join together to form a swirling flow F3.

  The swirling flow F3 is controlled by the control device 90 based on the control information stored for each of the compression mechanisms 20, 30, and 40, and the flow rates of the first flow rate adjustment valve 66, the second flow rate adjustment valve 76, and the third flow rate adjustment valve 86. By adjusting the ratio, a target swirl flow can be formed.

  The first downstream channel 65 is provided with a throat shape 65a at the straight line portion of the confluence 18b. Thereby, the flow velocity of the refrigerant flowing downstream of the throat shape 65a can be higher than that of the refrigerant flowing upstream of the throat shape 65a.

  Although the suction side of the second compression mechanism 20 has been described above, the same applies to the suction side of the third compression mechanism 30 and the suction side of the fourth compression mechanism 40.

  In addition, the mass flow rate of the refrigerant required for the first downstream flow path 65 stored in advance in the control memory 92 described above, the mass flow rate of the refrigerant required for the second downstream flow path 75, and The mass flow rate of the refrigerant required in the third downstream flow path 85 is a value in which the effect of increasing the flow velocity due to each throat shape is considered in advance.

(5) Features In the heat pump device 1 of the above-described embodiment, when the operation close to the target set temperature is performed, the mass flow rate of the refrigerant flowing through the first injection pipe 63 of the first economizer circuit 60, the second of the second economizer circuit 70 By controlling the mass flow rate of the refrigerant flowing through the injection pipe 73 and the mass flow rate of the refrigerant flowing through the third injection pipe 83 of the third economizer circuit 80 by the control device 90, the operating efficiency of the refrigeration cycle can be improved. It is possible.

  In the heat pump device 1, desired swirling flows can be generated for the suction refrigerant of the second compression mechanism 20, the suction refrigerant of the third compression mechanism 30, and the suction refrigerant of the fourth compression mechanism 40, respectively. When the refrigerant flows into the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40, it is possible to suppress the pressure loss that occurs according to the blade inclination angle and the rotation speed (rpm) to the lowest possible value. It has become.

  In addition, even when the control device 90 performs control to adjust the swirling flow of the suction refrigerant of the second compression mechanism 20, the third compression mechanism 30, and the fourth compression mechanism 40, the control device 90 flows through the first injection pipe 63. The mass flow rate of the refrigerant (total value of the mass flow rates of the refrigerant flowing through the first downstream channel 65 and the first upstream channel 64) and the mass flow rate of the refrigerant flowing through the second injection pipe 73 (second downstream channel 75) And the total mass flow rate of the refrigerant flowing through the second upstream flow path 74) and the mass flow rate of the refrigerant flowing through the third injection pipe 83 (of the refrigerant flowing through the third downstream flow path 85 and the third upstream flow path 84) Since there is no change in the total mass flow rate), it is possible to maintain the operating efficiency of the refrigeration cycle in a good state.

  For example, when the amount of refrigerant flowing through the first injection pipe 63, the second injection pipe 73, and the third injection pipe 83 is adjusted to be small by the control for improving the operation efficiency of the refrigeration cycle, The amount of refrigerant flowing through the first downstream channel 65, the second downstream channel 75, and the third downstream channel 85 also tends to decrease, and the flow rate of the refrigerant for generating the swirling flow tends to be slow. On the other hand, in the heat pump apparatus 1 of the said embodiment, in order to improve the flow velocity of the refrigerant | coolant which produces a swirl | flow, the throat shape 65a is employ | adopted. For this reason, it is easy to achieve both the desired swirling flow and the improvement of the operating efficiency of the refrigeration cycle at the same time. Further, when the amount of refrigerant flowing in any or all of the first injection pipe 63, the second injection pipe 73, and the third injection circuit 83 is small, or flows through the outlet of the first economizer heat exchanger 61 of the first injection pipe 63. The differential pressure between the refrigerant pressure and the suction refrigerant pressure at the suction destination, the differential pressure between the pressure of the refrigerant flowing through the outlet of the second economizer heat exchanger 71 of the second injection pipe 73 and the suction refrigerant pressure at the suction destination, a third injection circuit 83 If any or all of the differential pressure between the refrigerant pressure flowing through the outlet of the third economizer heat exchanger 81 and the suction refrigerant pressure at the suction destination is small, and the amount of refrigerant is small as described above and the difference as described above. In any case where the pressure is small, it is possible to easily form a target swirl flow.

(6) Other embodiments (6-1)
In the said embodiment, the case where a swirling flow was produced by one refrigerant flow branched from the refrigerant flowing through the injection pipe was described as an example.

  However, the present invention is not limited to this. For example, as shown in FIG. 8, the swirl flow that is further branched from the middle of the first downstream flow path 65 and is generated by the first downstream flow path 65 is further strengthened. It is good also as a structure which has the opposing downstream flow path 265 which joins the 1st intermediate | middle connection pipe 18. FIG.

  Also in the opposed downstream channel 265, a throat shape 265 a that generates the refrigerant flow F 202 may be formed in the same manner as the throat shape 65 a in the first downstream channel 65.

(6-2)
In the above embodiment, the case where the throat shape is used to generate the swirl flow has been described as an example.

  However, the present invention is not limited to this.

  For example, the first economizer circuit 60, the second economizer circuit 70, and the third economizer circuit 80 are used in a usage environment in which an appropriate flow rate is secured as the amount of refrigerant to be injected in order to improve the operation efficiency of the refrigeration cycle. If so, it is possible to obtain the same effect as in the above embodiment by controlling only the first flow rate adjustment valve 66, the second flow rate adjustment valve 76, and the third flow rate adjustment valve 86 without adopting the throat shape. is there.

(6-3)
If the impeller 11, 21, 31, 41 of the above embodiment can reduce the pressure loss as described above in relation to the swirling flow generated by the injection, the large blade and the small blade are both left in the front view. You may comprise what is called a "backward wing | blade" by extending spirally so that it may become a winding. Similarly, as long as the pressure loss can be reduced as described above in relation to the swirling flow generated by the injection, so-called “forward blades” and “radial blades” may be configured. The same applies to the relationship between the rotation direction of the impellers 11, 21, 31, and 41 and the pressure loss.

  Further, in the impellers 11, 21, 31, and 41 of the above-described embodiment, the large blades and the small blades may be provided substantially perpendicular to the diameter-expanded curved surface, or the rotational traveling direction R or the rotational traveling direction R. It may be inclined and provided on the opposite side. Also in this case, it is preferable that the pressure loss is less likely to occur due to the swirl flow generated by the injection.

  In addition, the impellers 11, 21, 31, and 41 of the above-described embodiment may be configured, for example, by providing only large blades without providing small blades.

(6-4)
In the above embodiment, an example of a multistage compression refrigeration cycle has been described. However, an intake guide vane is installed at a junction (near the outlet) of each of the first injection circuit 63, the second injection circuit 73, and the third injection circuit 83. Thus, it becomes possible to generate the pre-swirl flow with a simple structure.

(6-5)
In the embodiment described above, a four-stage compression mechanism has been described as an example of the multistage compression mechanism.

  However, the present invention is not limited to this, and may be, for example, a compression mechanism having two or more stages.

  The refrigerating apparatus of the present invention is particularly useful in a refrigerating apparatus having a compression mechanism having an impeller and an injection circuit because the swirling flow generated in the suction refrigerant can be adjusted using the refrigerant flow flowing through the injection circuit.

1 Heat pump equipment (refrigeration equipment)
2 Multistage centrifugal compressor (centrifugal compressor)
3 Heat source side heat exchanger (heatsink)
5 Use-side heat exchanger (evaporator)
8 Expansion mechanism 18, 28, 38 First to third intermediate connection pipes (m-stage intermediate connection pipes)
18b, 28b, 38b Merge point (downstream merge point)
22c shroud housing 22b front wall 10, 20, 30, 40 1st-4th compression mechanism (compression mechanism)
11, 21, 31, 41 Impeller 60, 70, 80 First to third economizer circuits (injection circuits)
61, 71, 81 1st to 3rd economizer heat exchanger (economizer heat exchanger)
64, 74, 84 First to third upstream flow paths (upstream flow paths)
65, 75, 85 First to third downstream channels (downstream channels)
65a Throat shape 66, 76, 86 1st-3rd flow control valve (adjustment mechanism)
212 Large feathers
213 Small feather (feather)

JP 2007-263440 A

Claims (3)

A refrigeration apparatus (1) for performing a multistage compression refrigeration cycle,
Each impeller (11, 21, 31, 41) is provided with a plurality of blades inclined, and n compression mechanisms (n is a natural number of 2 or more) connected in series (2, 10, 20, 30, 40),
A radiator (3) for radiating the heat of the refrigerant;
An expansion mechanism (8);
An evaporator (5) for heating the refrigerant;
m-stage intermediate connecting pipes (18, 28, 38) connecting the discharge side of the m-th stage compression mechanism (m is a natural number less than n) and the suction side of the m + 1-th stage compression mechanism;
An injection circuit (60, 70, 80) for branching a part of the refrigerant flow from the radiator toward the expansion mechanism and joining the m-stage intermediate connecting pipe (18, 28, 38);
An economizer heat exchanger (61, 71, 81) for performing heat exchange between the refrigerant from the radiator toward the expansion mechanism and the refrigerant flowing through the injection circuit;
An economizer expansion valve (62, 72, 82) provided in the middle of the injection circuit (60, 70, 80) and upstream of a portion where heat exchange is performed in the economizer heat exchanger;
A control unit (90);
With
The injection circuit is
An upstream flow path (64, 74, 84) for guiding a part of the refrigerant that has passed through the economizer expansion valve to the upstream confluence (18a, 28a, 38a) of the m-stage intermediate connecting pipe;
Downstream of the m-stage intermediate connecting pipe downstream from the upstream junction so that the other part of the refrigerant that has passed through the economizer expansion valve is swirled to the suction refrigerant of the m + 1-stage compression mechanism Downstream flow paths (65, 75, 85) leading to the junction (18b, 28b, 38b);
An adjustment mechanism (66, 76, 86) for adjusting a refrigerant flow rate ratio between the upstream channel and the downstream channel;
And have a,
The control unit controls the adjustment mechanism to control the adjustment mechanism while controlling the valve opening degree of the economizer expansion valve so that the superheat degree of the refrigerant discharged from the m + 1 stage compression mechanism becomes a target superheat degree. By adjusting the flow rate ratio, the swirl flow generated in the suction refrigerant of the m + 1 stage compression mechanism is adjusted,
Refrigeration equipment (1). The control unit has a flow rate ratio determined in advance according to a differential pressure between the pressure of the refrigerant flowing through the outlet of the economizer heat exchanger of the injection circuit and the pressure of the suction refrigerant of the m + 1 stage compression mechanism. Controlling the adjusting mechanism;
The refrigeration apparatus according to claim 1. The downstream channel has a throat shape (65a).
The refrigeration apparatus according to claim 1 or 2.

Images