WO2019171740A1

WO2019171740A1 - Dynamic compressor and refrigeration cycle device

Info

Publication number: WO2019171740A1
Application number: PCT/JP2019/000136
Authority: WO
Inventors: 洪志孫; 直芳庄山; 文紀河野; 朋一郎田村; 良美林; 松井　大
Original assignee: パナソニック株式会社
Priority date: 2018-03-05
Filing date: 2019-01-08
Publication date: 2019-09-12

Abstract

A dynamic compressor of the present disclosure is provided with: a rotating body which includes a rotating shaft and at least one impeller; a refrigerant flow passageway which is positioned around the rotating body and through which a gas-phase refrigerant flows; a main-flow passageway which is disposed in the rotating body and extends in an axial direction of the rotating body, and through which a liquid-phase refrigerant flows; and an injection flow passageway which is positioned in the rotating body, diverges from the main-flow passageway, and extends from the main-flow passageway to the refrigerant flow passageway, the injection flow passageway guiding the liquid-phase refrigerant from the main-flow passageway to the refrigerant flow passageway.

Description

Speed type compressor and refrigeration cycle apparatus

This disclosure relates to a speed type compressor and a refrigeration cycle apparatus.

As a conventional refrigeration cycle apparatus, a refrigeration cycle having a two-stage compressor is configured such that refrigerant vapor discharged from the first-stage compressor is cooled before being sucked into the second-stage compressor. The device is known.

As shown in FIG. 21, the air conditioning apparatus 500 described in Patent Document 1 includes an evaporator 510, a centrifugal compressor 531, a steam cooler 533, a roots compressor 532, and a condenser 520. A centrifugal compressor 531 is provided at the front stage, and a Roots compressor 532 is provided at the rear stage. The evaporator 510 generates saturated refrigerant vapor. The refrigerant vapor is sucked into the centrifugal compressor 531 and compressed. The refrigerant vapor compressed by the centrifugal compressor 531 is further compressed by the roots compressor 532. In the steam cooler 533 disposed between the centrifugal compressor 531 and the roots compressor 532, the refrigerant vapor is cooled.

The steam cooler 533 is provided between the centrifugal compressor 531 and the roots compressor 532. In the steam cooler 533, water is sprayed directly on the refrigerant vapor. Alternatively, in the steam cooler 533, heat exchange is indirectly performed between a cooling medium such as air and the refrigerant vapor.

JP 2008-122012 A

According to the technique described in Patent Document 1, in the steam cooler 533, the degree of superheat of the refrigerant to be sucked into the roots compressor 532 can be reduced. However, the degree of superheat generated in the compression process of the centrifugal compressor 531 and the degree of superheat generated in the compression process of the roots compressor 532 cannot be removed in the compression process.

This disclosure
A rotating body including a rotating shaft and at least one impeller;
A refrigerant passage located around the rotating body and through which a gas-phase refrigerant flows;
A main flow path that extends in the axial direction of the rotating body inside the rotating body and through which a liquid-phase refrigerant flows;
An injection flow path that is located inside the rotating body, extends from the main flow path to the refrigerant flow path, branches from the main flow path, and guides the liquid-phase refrigerant from the main flow path to the refrigerant flow path;
A speed type compressor is provided.

According to the present disclosure, the degree of superheat generated in the compression process can be removed in the compression process. Thereby, the efficiency of the refrigeration cycle apparatus can be improved.

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present disclosure. FIG. 2 is a cross-sectional view of the speed compressor according to the first embodiment of the present disclosure. FIG. 3 is a cross-sectional view of the rotating body taken along line III-III. FIG. 4A is a cross-sectional view of a rotating body according to a modification. FIG. 4B is a partial side view of a rotating shaft according to a modification. FIG. 5 is a cross-sectional view of a compressor according to a modification. FIG. 6 is a cross-sectional view of a compressor according to another modification. FIG. 7 is an enlarged plan view of the impeller showing the vicinity of the injection flow path in an enlarged manner. FIG. 8 is an enlarged plan view of the impeller showing the vicinity of the injection flow path (static coordinate system). FIG. 9 is a graph showing the outflow angle necessary to avoid the collision of the refrigerant droplets. FIG. 10 is a cross-sectional view of a multistage speed compressor according to still another modification. FIG. 11 is a cross-sectional view of the first impeller and the second impeller. FIG. 12 is a cross-sectional view of the impeller at a position including the injection flow path. FIG. 13 is a cross-sectional view of a multistage speed compressor according to still another modification. FIG. 14 is a cross-sectional view of a speed type compressor according to still another modification. FIG. 15 is a cross-sectional view of a speed type compressor according to still another modification. FIG. 16 is a cross-sectional view of a speed compressor according to still another modification. FIG. 17 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present disclosure. FIG. 18 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 3 of the present disclosure. FIG. 19 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 4 of the present disclosure. FIG. 20 is a flowchart illustrating the compression method of the present disclosure. FIG. 21 is a configuration diagram of a conventional air conditioner.

(Knowledge that became the basis of this disclosure)
According to the air conditioner described in Patent Document 1, in the steam cooler 533, the degree of superheat of the refrigerant sucked into the roots compressor 532 can be reduced. However, the degree of superheat generated in the compression process of the centrifugal compressor 531 and the degree of superheat generated in the compression process of the roots compressor 532 cannot be removed in the compression process. As the degree of superheat of the refrigerant increases, the enthalpy of the refrigerant also increases.

The ideal compression process in a compressor is along a completely adiabatic isentropic line. In the refrigerant ph diagram, as the enthalpy of the refrigerant increases, the slope of the isentropic line becomes gentler, and a larger compression power is required. As the degree of superheat of the refrigerant increases, greater compression power is required to raise the pressure of the unit mass refrigerant to a predetermined pressure. In other words, the load on the compressor increases and the power consumption of the compressor increases.

This disclosure provides a technique for removing superheat generated in the compression process in the compression process. In addition, the present disclosure provides a technique for improving the efficiency of the refrigeration cycle apparatus.

(Outline of one aspect according to the present disclosure)
The speed type compressor according to the first aspect of the present disclosure is:
A rotating body including a rotating shaft and at least one impeller;
A refrigerant passage located around the rotating body and through which a gas-phase refrigerant flows;
A main flow path that extends in the axial direction of the rotating body inside the rotating body and through which a liquid-phase refrigerant flows;
An injection flow path that is located inside the rotating body, extends from the main flow path to the refrigerant flow path, branches from the main flow path, and guides the liquid-phase refrigerant from the main flow path to the refrigerant flow path;
It has.

According to the first aspect, the liquid-phase refrigerant is pressurized by centrifugal force, and is injected toward the refrigerant flow path inside the compressor through the main flow path and the injection flow path. When the liquid-phase refrigerant contacts the gas-phase refrigerant in the refrigerant flow path, heat exchange occurs between the liquid-phase refrigerant and the gas-phase refrigerant, and the superheated gas-phase refrigerant is continuously generated by the sensible heat or latent heat of vaporization of the liquid-phase refrigerant. To be cooled. Thereby, the increase in the enthalpy of the refrigerant due to the increase in the degree of superheat of the refrigerant in the compression process is continuously suppressed. The compression power required by the compressor can be reduced below that required for fully adiabatic isentropic compression. The work to be done by the compressor to raise the refrigerant pressure to a predetermined pressure can be greatly reduced. That is, the power consumption of the compressor can be greatly saved.

In the second aspect of the present disclosure, for example, in the speed type compressor according to the first aspect, the impeller may include a hub and a blade fixed to the hub, and the injection flow path includes the refrigerant You may have the outflow port which faces the flow path, and the said outflow port may be located in an upstream rather than the upstream end of the said blade in the flow direction of the said gaseous-phase refrigerant | coolant. According to such a configuration, it is possible to efficiently remove heat from the gas phase refrigerant in the compression process.

In the third aspect of the present disclosure, for example, in the speed type compressor according to the first or second aspect, the impeller may include a hub and a blade fixed to the hub, and the injection flow path is The outlet may be located on the surface of the hub, and may pass through the hub in the radial direction of the rotating shaft. According to such a configuration, the gas phase refrigerant and the liquid phase refrigerant can be mixed before the gas phase refrigerant enters the inter-blade flow path between the blades. Thereby, it is possible to efficiently remove heat from the gas phase refrigerant in the compression process.

In the fourth aspect of the present disclosure, for example, in the speed type compressor according to any one of the first to third aspects, the injection flow path has a radius of the rotation shaft from the main flow path inside the rotation shaft. The 1st part extended in the direction and the 2nd part located between the said 1st part and the said refrigerant | coolant flow path may be included. According to such a configuration, it is possible to sufficiently ensure the length of the ejection flow path. The longer the injection channel, the greater the centrifugal acceleration applied to the liquid phase refrigerant, and the easier it is to inject the liquid phase refrigerant into the refrigerant channel.

In the fifth aspect of the present disclosure, for example, in the speed type compressor according to the fourth aspect, the number of the injection flow paths including the first portion and the second portion may be two or more. According to such a configuration, the gas-phase refrigerant can be uniformly cooled in the circumferential direction of the rotating shaft.

In the sixth aspect of the present disclosure, for example, in the speed type compressor according to the fourth or fifth aspect, the first portion includes a groove provided on a side surface of the rotating shaft along a circumferential direction of the rotating shaft. The second portion may be connected to the groove. According to such a configuration, since the alignment of the first portion and the second portion in the circumferential direction of the rotation shaft is extremely easy or unnecessary, the operation of attaching the impeller to the rotation shaft is easy.

In the seventh aspect of the present disclosure, for example, in the speed type compressor according to any one of the first to sixth aspects, the main flow path has an inflow port located on an end surface of the rotation shaft. May be. According to such a configuration, the liquid phase refrigerant can be smoothly fed into the main flow path.

In the eighth aspect of the present disclosure, for example, the speed type compressor according to any one of the first to seventh aspects is in contact with a supply tank in which the liquid refrigerant is stored and an inlet to the main flow path. The apparatus may further include a buffer chamber and a pressure pump that pumps the liquid-phase refrigerant from the supply tank to the buffer chamber through a refrigerant supply path connected to the buffer chamber. According to such a configuration, the liquid phase refrigerant is pressurized by the pressurizing pump, and the pressure of the liquid phase refrigerant rises to raise the boiling point. It becomes possible to suppress.

In the ninth aspect of the present disclosure, for example, the speed compressor according to the eighth aspect may further include a heat exchanger that exchanges heat with an external heat source, and the refrigerant supply path includes the buffer chamber and the heating chamber. The flow path may be connected to a pressure pump, and the heat exchanger may be provided in the refrigerant supply path between the buffer chamber and the pressure pump. According to such a configuration, since the liquid phase refrigerant is cooled by the heat exchanger 23, the liquid phase refrigerant in the supercooled state is supplied to the main flow path 21, and the liquid phase refrigerant is contained in the main flow path 21. Difficult to evaporate.

In the tenth aspect of the present disclosure, for example, in the speed type compressor according to any one of the first to ninth aspects, the impeller may include a hub and a plurality of blades fixed to the hub. The injection channel may have an outlet that faces the refrigerant channel, and is closest to the outlet in the direction of rotation opposite to the direction of rotation of the rotating body. In the projection obtained by defining the blade as a first blade and projecting the blade root line of the first blade onto a plane perpendicular to the rotation axis, the outermost peripheral portion of the blade root line is defined as a first rear end. When defining the edge, defining a line extending radially from the central axis of the rotating body through the outlet as the r-axis, and defining the rotational direction of the rotating body as the positive direction, the first trailing edge The angle formed by the line connecting the center axis and the central axis and the r axis The angle measured from the r-axis along the rotation direction of the rotating body may be -40 degrees or more, and the central axis of the rotating body with respect to the distance from the central axis of the rotating body to the outlet The ratio of the distance from the first trailing edge to the first trailing edge may be 3 or more, and is obtained by projecting the outflow direction of the liquid-phase refrigerant injected from the outflow port onto the plane perpendicular to the rotation axis. In the projected view, the angle when the angle formed between the outflow direction of the liquid refrigerant and the r-axis is measured from the r-axis along the rotation direction of the rotating body may be −25 degrees or more. . According to such a configuration, the amount of angular movement of the refrigerant droplet in the circumferential direction due to the Coriolis force is equal to or less than the angle formed by the line connecting the trailing edge of the blade and the rotation axis and the r axis, and the large refrigerant droplet Can collide with the trailing edge of the blade. Therefore, erosion of the impeller can be prevented.

In an eleventh aspect of the present disclosure, for example, in the speed type compressor according to any one of the first to tenth aspects, the at least one impeller may include a first impeller and a second impeller, The injection flow path may be provided in each of the first impeller and the second impeller, and an opening area of an outlet of the injection flow path provided in the first impeller is defined as S ₁ , the opening area of the outlet of the injection passage provided on the second impeller is defined as S _2, the distance from the center axis of the rotary body to said outlet of said injection passage provided on the first impeller is defined as R _1, and the distance from the rotary body center axis to the outlet of the injection passage provided on the second impeller is defined as _{_{R 2, (R 2 / R}} 1 ≦ S 1 / S 2 _{relationship)} may be filled According to such a configuration, the injection amount from the injection flow path of the second impeller is equal to or less than the injection amount from the injection flow path of the first impeller. As a result, it is possible to prevent liquid phase refrigerant having a large particle diameter that does not follow the gas phase refrigerant from colliding with the impeller wall surface and staying there.

In a twelfth aspect of the present disclosure, for example, in the speed type compressor according to any one of the first to eleventh aspects, the at least one impeller may include a first impeller and a second impeller, The speed type compressor may further include a first diffuser facing the first impeller, and the first impeller is located inside the first impeller and is branched from the main flow path to branch into the main flow There may be provided a downstream injection passage extending from the passage to the refrigerant passage, and the downstream injection passage is located downstream of the injection passage in the flow direction of the gas-phase refrigerant. Alternatively, the central axis of the downstream injection flow path may intersect the inlet of the first diffuser. According to such a configuration, the amount of refrigerant droplets existing in each of the refrigerant flow path around the first impeller and the refrigerant flow path around the second impeller is reduced. As a result, the collision probability of the refrigerant droplets on the first impeller and the second impeller is reduced, and the erosion risk of the first impeller and the second impeller is reduced.

In the thirteenth aspect of the present disclosure, for example, the speed compressor according to the twelfth aspect may further include a second diffuser facing the second impeller, and the second impeller includes the second impeller. There may be provided a second injection channel that is branched from the main channel and extends from the main channel to the refrigerant channel, and the central axis of the second injection channel is It may cross the entrance of the second diffuser. According to such a configuration, heat can also be taken from the gas-phase refrigerant when pressure recovery is performed in the second diffuser.

A refrigeration cycle apparatus according to a fourteenth aspect of the present disclosure includes:
An evaporator,
Any one speed type compressor according to the first to thirteenth aspects;
A condenser,
It has.

According to the fourteenth aspect, the efficiency of the refrigeration cycle apparatus is improved by greatly saving the power consumption of the speed type compressor.

In the fifteenth aspect of the present disclosure, for example, in the refrigeration cycle apparatus according to the fourteenth aspect, the evaporator may store a liquid phase refrigerant therein, and the condenser stores the liquid phase refrigerant therein. The refrigeration cycle apparatus may further include a refrigerant supply path that guides the liquid phase refrigerant stored in the evaporator or the liquid phase refrigerant stored in the condenser to the speed compressor. Also good. According to such a configuration, the liquid phase refrigerant can be reliably supplied to the main flow path of the speed compressor.

A compression method according to the sixteenth aspect of the present disclosure includes:
A compression method using a speed type compressor,
The speed compressor includes a rotating body including a rotating shaft and an impeller, and a refrigerant flow path that is positioned around the rotating body and that flows the gas-phase refrigerant from a gas-phase refrigerant inlet to a gas-phase refrigerant outlet. When,
With
The compression method is:
Inhaling the gas phase refrigerant into the speed compressor;
Accelerating and compressing the sucked gas phase refrigerant in the speed type compressor;
A flow path communicating with an outlet disposed on the surface of the rotating body, passing through the flow path located inside the rotating body, toward the gas-phase refrigerant existing in the refrigerant flow path. Injecting liquid phase refrigerant from the outlet;
including.

According to the sixteenth aspect, the same effect as in the first aspect can be obtained.

In the seventeenth aspect of the present disclosure, for example, in the compression method according to the sixteenth aspect, the flow path located inside the rotating body may extend in the axial direction of the rotating body inside the rotating body, A main flow path through which the liquid-phase refrigerant flows, and is located inside the rotating body, branches from the main flow path and extends from the main flow path to the refrigerant flow path, and the liquid flows from the main flow path to the refrigerant flow path. The liquid phase refrigerant that flows through the main channel may flow in a direction opposite to the direction in which the gas-phase refrigerant is sucked and flows.

In the eighteenth aspect of the present disclosure, for example, in the compression method according to the sixteenth or seventeenth aspect, the liquid-phase refrigerant may be injected from the outlet through the centrifugal force generated by the rotation of the rotating body. The liquid refrigerant thus made may be sucked into the inter-blade channel of the speed type compressor. Liquid phase refrigerant can be efficiently injected by the centrifugal force of the rotating body.

In the nineteenth aspect of the present disclosure, for example, in the compression method according to any one of the sixteenth to eighteenth aspects, the impeller may include a hub and a blade fixed to the hub, and the flow The outlet may be located upstream of the upstream end of the blade in the flow direction of the gas-phase refrigerant. According to such a configuration, it is possible to efficiently remove heat from the gas phase refrigerant in the compression process.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

(Embodiment 1)
FIG. 1 shows a configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present disclosure. The refrigeration cycle apparatus 100 includes an evaporator 2, a compressor 3, a condenser 4, and a refrigerant supply path 11. The compressor 3 is connected to the evaporator 2 by a suction pipe 6 and is connected to the condenser 4 by a discharge pipe 8. Specifically, a suction pipe 6 is connected to the outlet of the evaporator 2 and the suction port of the compressor 3. A discharge pipe 8 is connected to the discharge port of the compressor 3 and the inlet of the condenser 4. The condenser 4 is connected to the evaporator 2 by a return path 9. The evaporator 2, the compressor 3 and the condenser 4 are connected in an annular shape in this order to form a refrigerant circuit 10.

In the evaporator 2, the refrigerant evaporates, and a gas phase refrigerant (refrigerant vapor) is generated. The gas-phase refrigerant generated in the evaporator 2 is sucked into the compressor 3 through the suction pipe 6 and compressed. The compressed gas phase refrigerant is supplied to the condenser 4 through the discharge pipe 8. In the condenser 4, the gas phase refrigerant is cooled to generate a liquid phase refrigerant (refrigerant liquid). The liquid phase refrigerant is sent from the condenser 4 to the evaporator 2 through the return path 9.

As the refrigerant of the refrigeration cycle apparatus 100, a fluorocarbon refrigerant, a low GWP (Global Warming Potential) refrigerant, and a natural refrigerant can be used. Examples of the fluorocarbon refrigerant include HCFC (hydrochlorofluorocarbon), HFC (hydrofluorocarbon), and the like. Examples of the low GWP refrigerant include HFO-1234yf. Examples of natural refrigerants include CO ₂ and water.

The refrigeration cycle apparatus 100 includes, for example, a substance whose saturation vapor pressure at normal temperature (Japanese Industrial Standard: 20 ° C. ± 15 ° C./JIS Z8703) is negative (absolute pressure lower than atmospheric pressure) as a main component. Refrigerant is filled. Examples of such a refrigerant include a refrigerant containing water as a main component. The “main component” means a component that is contained most in mass ratio.

When water is used as the refrigerant, the pressure ratio in the refrigeration cycle increases, and the degree of superheat of the refrigerant tends to become excessive. In the present embodiment, the liquid-phase refrigerant is injected toward the refrigerant flow path inside the compressor 3, and an increase in the enthalpy of the refrigerant due to the increase in the degree of superheat of the refrigerant in the compression process is continuously suppressed. Thereby, the work which the compressor 3 should do in order to raise the pressure of a refrigerant | coolant to a predetermined pressure can be reduced significantly. That is, the power consumption of the compressor 3 can be greatly saved.

The refrigeration cycle apparatus 100 further includes a heat absorption circuit 12 and a heat dissipation circuit 14.

The heat absorption circuit 12 is a circuit for using the liquid phase refrigerant cooled by the evaporator 2 and has necessary devices such as a pump and an indoor heat exchanger. A part of the heat absorption circuit 12 is located inside the evaporator 2. In the evaporator 2, a part of the endothermic circuit 12 may be located above the liquid level of the liquid phase refrigerant or may be located below the liquid level of the liquid phase refrigerant. The heat absorption circuit 12 is filled with a heat medium such as water or brine.

The liquid-phase refrigerant stored in the evaporator 2 comes into contact with members (piping) constituting the heat absorption circuit 12. Thereby, heat exchange is performed between the liquid phase refrigerant and the heat medium inside the heat absorption circuit 12, and the liquid phase refrigerant evaporates. The heat medium in the endothermic circuit 12 is cooled by the latent heat of vaporization of the liquid refrigerant. For example, when the refrigeration cycle apparatus 100 is an air conditioner that cools a room, the room air is cooled by the heat medium of the heat absorption circuit 12. The indoor heat exchanger is, for example, a fin tube heat exchanger.

The heat dissipation circuit 14 is a circuit used to take heat from the refrigerant inside the condenser 4 and has necessary devices such as a pump and a cooling tower. A part of the heat dissipation circuit 14 is located inside the condenser 4. Specifically, a part of the heat dissipation circuit 14 is located above the liquid level of the liquid-phase refrigerant in the condenser 4. The heat dissipation circuit 14 is filled with a heat medium such as water or brine. When the refrigeration cycle apparatus 100 is an air conditioner that cools a room, the condenser 4 is disposed outside the room, and the refrigerant in the condenser 4 is cooled by the heat medium of the heat dissipation circuit 14.

The high-temperature gas-phase refrigerant discharged from the compressor 3 contacts a member (pipe) constituting the heat dissipation circuit 14 inside the condenser 4. Thereby, heat exchange is performed between the gas-phase refrigerant and the heat medium inside the heat dissipation circuit 14, and the gas-phase refrigerant is condensed. The heat medium inside the heat dissipation circuit 14 is heated by the condensation latent heat of the gas-phase refrigerant. The heat medium heated by the gas-phase refrigerant is cooled by outside air or cooling water in a cooling tower (not shown) of the heat dissipation circuit 14, for example.

The evaporator 2 is constituted by a container having heat insulation and pressure resistance, for example. The evaporator 2 stores the liquid phase refrigerant and evaporates the liquid phase refrigerant inside. The liquid refrigerant inside the evaporator 2 absorbs heat generated from the outside of the evaporator 2 and evaporates. That is, the liquid-phase refrigerant heated by absorbing heat from the heat absorption circuit 12 evaporates in the evaporator 2. In the present embodiment, the liquid-phase refrigerant stored in the evaporator 2 indirectly contacts the heat medium circulating in the heat absorption circuit 12. That is, a part of the liquid phase refrigerant stored in the evaporator 2 is heated by the heat medium of the heat absorption circuit 12 and used to heat the liquid phase refrigerant in the saturated state. The temperature of the liquid-phase refrigerant stored in the evaporator 2 and the temperature of the gas-phase refrigerant generated in the evaporator 2 are 5 ° C., for example.

In the present embodiment, the evaporator 2 is an indirect contact heat exchanger (for example, a shell tube heat exchanger). However, the evaporator 2 may be a direct contact type heat exchanger such as a spray type or filler type heat exchanger. That is, the liquid phase refrigerant may be heated by circulating the liquid phase refrigerant in the heat absorption circuit 12. Further, the endothermic circuit 12 may be omitted.

The compressor 3 sucks and compresses the gas-phase refrigerant generated by the evaporator 2. The compressor 3 is a speed type compressor (dynamic compressor). The speed type compressor is a compressor that increases the pressure of the gas-phase refrigerant by giving momentum to the gas-phase refrigerant and then decelerating it. Examples of the speed type compressor include a centrifugal compressor, a mixed flow compressor, and an axial flow compressor. The speed type compressor is also called a turbo compressor. The compressor 3 may include a variable speed mechanism for changing the rotation speed. An example of the variable speed mechanism is an inverter that drives the motor of the compressor 3. The temperature of the refrigerant at the discharge port of the compressor 3 is in the range of 100 to 150 ° C., for example.

The condenser 4 is constituted by a container having heat insulation and pressure resistance, for example. The condenser 4 condenses the gas-phase refrigerant compressed by the compressor 3 and stores the liquid-phase refrigerant generated by condensing the gas-phase refrigerant. In the present embodiment, the gas-phase refrigerant indirectly condenses and condenses on the heat medium cooled by releasing heat to the external environment. That is, the gas phase refrigerant is cooled and condensed by the heat medium of the heat dissipation circuit 14. The temperature of the gas-phase refrigerant introduced into the condenser 4 is in the range of 100 to 150 ° C., for example. The temperature of the liquid phase refrigerant stored in the condenser 4 is, for example, 35 ° C.

In the present embodiment, the condenser 4 is an indirect contact heat exchanger (for example, a shell tube heat exchanger). However, the condenser 4 may be a direct contact type heat exchanger such as a spray type or filler type heat exchanger. That is, the liquid phase refrigerant may be cooled by circulating the liquid phase refrigerant in the heat dissipation circuit 14. Further, the heat dissipation circuit 14 may be omitted.

The suction pipe 6 is a flow path for guiding the gas-phase refrigerant from the evaporator 2 to the compressor 3. The outlet of the evaporator 2 is connected to the suction port of the compressor 3 through the suction pipe 6.

The discharge pipe 8 is a flow path for guiding the gas-phase refrigerant compressed from the compressor 3 to the condenser 4. The discharge port of the compressor 3 is connected to the inlet of the condenser 4 via the discharge pipe 8.

The return path 9 is a flow path for guiding the liquid refrigerant from the condenser 4 to the evaporator 2. The evaporator 2 and the condenser 4 are connected by the return path 9. A pump, a flow rate adjusting valve, or the like may be disposed in the return path 9. The return path 9 can be constituted by at least one pipe.

The refrigerant supply path 11 connects the evaporator 2 and the compressor 3. The liquid phase refrigerant stored in the evaporator 2 is supplied to the compressor 3 through the refrigerant supply path 11. The liquid-phase refrigerant is injected toward the refrigerant flow path inside the compressor 3. The refrigerant supply path 11 can be configured by at least one pipe. In the evaporator 2, the inlet of the refrigerant supply path 11 is positioned below the liquid level of the liquid-phase refrigerant stored in the evaporator 2. A pump, a valve, or the like may be disposed in the refrigerant supply path 11.

The refrigeration cycle apparatus 100 may include a reserve tank that stores liquid phase refrigerant. The spare tank is connected to the evaporator 2, for example. The liquid phase refrigerant is transferred from the evaporator 2 to the spare tank. The refrigerant supply path 11 connects the auxiliary tank and the compressor 3 so that liquid refrigerant is supplied from the auxiliary tank to the compressor 3. The spare tank may be connected to the suction pipe 6. In this case, the reserve tank may store the liquid phase refrigerant supplied from within the refrigeration cycle, or store the liquid phase refrigerant generated by being cooled by an external heat source via the inner peripheral surface of the suction pipe 6 or the like. May be.

Next, the structure of the compressor 3 will be described in detail.

As shown in FIG. 2, the compressor 3 is a centrifugal compressor. The compressor 3 includes a rotating body 27, a housing 35, and a shroud 37. The rotating body 27 is disposed in a space surrounded by the housing 35 and the shroud 37. A motor (not shown) for rotating the rotating body 27 may be disposed inside the housing 35.

The rotating body 27 includes a rotating shaft 25 and an impeller 26. The impeller 26 is attached to the rotating shaft 25 and rotates at a high speed together with the rotating shaft 25. The impeller 26 may be formed integrally with the rotary shaft 25. The rotational speeds of the rotary shaft 25 and the impeller 26 are, for example, in the range of 5000 to 100,000 rpm. The rotating shaft 25 is made of a high-strength iron-based material such as S45CH. The impeller 26 is made of a material such as aluminum, duralumin, iron, or ceramic.

The impeller 26 has a hub 30 and a plurality of blades 31. The hub 30 is a portion fitted to the rotary shaft 25. In the cross section including the central axis O of the rotation shaft 25, the hub 30 has a diverging outline. The plurality of blades 31 are arranged on the surface 30 p of the hub 30 along the circumferential direction of the rotation shaft 25.

The space around the impeller 26 includes a refrigerant flow path 40, a diffuser 41, and a spiral chamber 42. The refrigerant flow path 40 is a flow path that is located around the rotating body 27 and through which the gas phase refrigerant to be compressed flows. The refrigerant flow path 40 includes a suction flow path 36 and a plurality of inter-blade flow paths 38. The suction flow path 36 is located upstream of the upstream end 31t of the blade 31 in the flow direction of the gas-phase refrigerant. The inter-blade channel 38 is located between the blades 31 adjacent to each other in the circumferential direction of the rotating shaft 25. When the impeller 26 rotates, a speed in the rotation direction is given to the gas-phase refrigerant flowing through each of the plurality of blade flow paths 38.

The diffuser 41 is a flow path for guiding the gas-phase refrigerant accelerated in the rotation direction by the impeller 26 to the spiral chamber 42. The channel cross-sectional area of the diffuser 41 increases from the refrigerant channel 40 toward the spiral chamber 42. This structure decelerates the flow rate of the gas-phase refrigerant accelerated by the impeller 26 and increases the pressure of the gas-phase refrigerant. The diffuser 41 is, for example, a vaneless diffuser configured by a flow path extending in the radial direction. In order to effectively increase the pressure of the refrigerant, the diffuser 41 may be a vane diffuser having a plurality of vanes and a plurality of flow paths partitioned by them.

The spiral chamber 42 is a spiral space in which the gas-phase refrigerant that has passed through the diffuser 41 is collected. The compressed gas-phase refrigerant is guided to the outside of the compressor 3 (discharge pipe 8) via the spiral chamber 42. The cross-sectional area of the spiral chamber 42 is enlarged along the circumferential direction, whereby the flow rate and angular momentum of the gas-phase refrigerant in the spiral chamber 42 are kept constant.

The shroud 37 covers the impeller 26 and defines the refrigerant flow path 40, the diffuser 41, and the spiral chamber 42. The shroud 37 is made of an iron-based material or an aluminum-based material. Examples of the iron-based material include FC250, FCD400, and SS400. ACD12 etc. are mentioned as an aluminum-type material.

The housing 35 serves as a casing that accommodates various components of the compressor 3. A spiral chamber 42 is formed by combining the housing 35 and the shroud 37. The housing 35 can be made of the iron-based material or the aluminum-based material described above. When the diffuser is a vaned diffuser, the plurality of vanes can also be made of the iron-based material or aluminum-based material described above.

The bearing 18 and the seal 29 are disposed inside the housing 35. The bearing 18 supports the rotating shaft 25 in a rotatable manner. The bearing 18 may be a sliding bearing or a rolling bearing. When the bearing 18 is a sliding bearing, the refrigerant of the refrigeration cycle apparatus 100 can be used as a lubricant. The bearing 18 is connected to the housing 35 directly or via a bearing box (not shown). The seal 29 prevents the lubricant of the bearing 18 from flowing toward the impeller 26. The seal 29 is, for example, a labyrinth seal.

The main flow path 21 and the injection flow path 24 are provided inside the rotating body 27. The main flow path 21 extends in the axial direction of the rotating body 27 inside the rotating body 27. Specifically, the main flow path 21 is provided inside the rotation shaft 25 and extends in the axial direction of the rotation shaft 25. The injection flow path 24 branches from the main flow path 21 inside the rotating body 27 and extends from the main flow path 21 to the refrigerant flow path 40. The main channel 21 is connected to the evaporator 2 through the refrigerant supply channel 11. The liquid refrigerant introduced from the refrigerant supply path 11 located outside the rotating body 27 flows through the main flow path 21. The injection flow path 24 is a flow path that guides the liquid phase refrigerant from the main flow path 21 to the refrigerant flow path 40.

The liquid phase refrigerant is supplied from the evaporator 2 to the main flow path 21 through the refrigerant supply path 11. The liquid-phase refrigerant is pressurized by centrifugal force and is injected toward the refrigerant flow path 40 inside the compressor 3 through the main flow path 21 and the injection flow path 24. When the liquid-phase refrigerant contacts the gas-phase refrigerant in the refrigerant channel 40, heat exchange occurs between the liquid-phase refrigerant and the gas-phase refrigerant, and the superheated gas-phase refrigerant continues due to sensible heat or latent heat of vaporization of the liquid-phase refrigerant. Cooled. Thereby, the increase in the enthalpy of the refrigerant due to the increase in the degree of superheat of the refrigerant in the compression process is continuously suppressed. The compression power required by the compressor 3 can be reduced below the compression power required for fully adiabatic isentropic compression. The work to be performed by the compressor 3 in order to increase the pressure of the refrigerant to a predetermined pressure can be greatly reduced. That is, the power consumption of the compressor 3 can be greatly saved. As a result, the efficiency of the refrigeration cycle apparatus 100 is improved.

The main flow path 21 has an inflow port 21 a located on the end face 25 c of the rotating shaft 25. The end face 25c is an end face located on the side opposite to the side where the impeller 26 is located. Liquid phase refrigerant is introduced into the main channel 21 from the inlet 21a. According to such a configuration, the liquid phase refrigerant can be smoothly fed into the main flow path 21. The main flow path 21 includes the central axis O of the rotation shaft 25. In the cross section of the rotating shaft 25, the main flow path 21 has, for example, a circular cross section. In the cross section of the rotating shaft 25, the center of the main channel 21 coincides with the central axis O. However, the center of the main channel 21 may be offset from the center axis O of the rotation shaft 25. In the axial direction of the rotary shaft 25, the main flow path 21 extends to the vicinity of the upper surface 26 t of the impeller 26.

The refrigerant supply path 11 can be connected to the connection port 28 of the housing 35. A buffer chamber 35 h communicating with the connection port 28 is provided inside the housing 35, and the liquid phase refrigerant is supplied from the refrigerant supply path 11 to the buffer chamber 35 h. The end surface 25c of the rotating shaft 25 faces the buffer chamber 35h. That is, the main flow path 21 opens toward the buffer chamber 35h. According to such a configuration, it is possible to smoothly feed the liquid-phase refrigerant from the refrigerant supply path 11 to the main flow path 21 via the buffer chamber 35h.

The position of the inlet 21 a of the main channel 21 is not limited to the end face 25 c of the rotating shaft 25. As will be described later, an inflow port 21 a may be provided on the side surface of the rotation shaft 25. In that case, the buffer chamber 35 h may surround the side surface of the rotation shaft 25 inside the housing 35. A detailed structure will be described later with reference to FIG.

The injection flow path 24 branches from the main flow path 21 and extends in the radial direction of the rotary shaft 25. Centrifugal force acts on the liquid phase refrigerant in the injection flow path 24. The liquid phase refrigerant is injected into the refrigerant flow path 40 by centrifugal force and mixed with the gas phase refrigerant sucked into the compressor 3. In the present embodiment, the ejection flow path 24 extends in a direction perpendicular to the axial direction of the rotation shaft 25. The injection flow path 24 has an outlet 24 b that faces the refrigerant flow path 40. The outflow port 24b is located upstream of the upstream end 31t of the blade 31 in the flow direction of the gas-phase refrigerant. According to such a configuration, it is possible to efficiently remove heat from the gas phase refrigerant in the compression process. The injection flow path 24 may have an orifice shape so that a mist-like liquid phase refrigerant is supplied to the refrigerant flow path 40.

In the present embodiment, the outlet 24b is located on the surface 30p of the hub 30 of the impeller 26. The injection flow path 24 penetrates the hub 30 in the radial direction of the rotation shaft 25. According to such a configuration, the gas-phase refrigerant and the liquid-phase refrigerant can be mixed before the gas-phase refrigerant enters the inter-blade channel 38 between the blades 31. Thereby, it is possible to efficiently remove heat from the gas phase refrigerant in the compression process.

The position of the outlet 24b is not limited to the position shown in FIG. The outflow port 24b may be located downstream of the upstream end 31t of the blade 31 in the flow direction of the gas-phase refrigerant. Further, the outlet 24b may be located upstream of the upper surface 26t of the impeller 26 in the flow direction of the gas-phase refrigerant. In this case, the outlet 24 b can be located on the side surface of the rotating shaft 25. These configurations can also remove heat from the gas phase refrigerant in the compression process.

In the present embodiment, the injection flow path 24 includes a first portion 241 and a second portion 242. The first portion 241 is a portion that extends in the radial direction of the rotary shaft 25 from the main flow path 21 inside the rotary shaft 25. The second part 242 is a part located between the first part 241 and the refrigerant flow path 40. The first portion 241 is located inside the rotation shaft 25. The second portion 242 is located inside the impeller 26. According to such a configuration, a sufficient length of the injection flow path 24 can be ensured. The longer the injection flow path 24, the higher the centrifugal acceleration applied to the liquid phase refrigerant, and the easier it is to inject the liquid phase refrigerant into the refrigerant flow path 40. When the tip of the rotating shaft 25 protrudes in the axial direction from the upper surface 26t of the impeller 26, a component different from the impeller 26 may be attached to the tip of the rotating shaft 25, and the second portion is inside the component. 242 may be located.

When the outlet 24b is located on the upstream side of the upper surface 26t of the impeller 26, the second portion 242 can be omitted, and the injection flow path 24 can be configured by only the first portion 241.

The flow passage cross-sectional area of the injection flow passage 24 is smaller than the flow passage cross-sectional area of the main flow passage 21. According to such a configuration, it is easy to supply the mist-like liquid phase refrigerant to the refrigerant flow path 40.

As shown in FIG. 3, in this embodiment, a plurality (two or more) of injection channels 24 are provided. The plurality of ejection channels 24 extend radially from the main channel 21. A liquid phase refrigerant is injected from each of the injection flow paths 24 into the refrigerant flow path 40. According to such a configuration, the gas-phase refrigerant can be uniformly cooled in the circumferential direction of the rotating shaft 25. However, when the compressor 3 has at least one injection flow path 24, the effect of the present disclosure is obtained. The injection flow path 24 may extend parallel to the radial direction of the impeller 26 as in the present embodiment, or may extend in a direction inclined with respect to the radial direction.

Specifically, in the circumferential direction of the rotating shaft 25, the outlets 24b of the injection flow path 24 are arranged at equal angular intervals. The outlet 24b of the ejection flow path 24 is located between the blades 31 adjacent to each other in the circumferential direction. A liquid phase refrigerant is injected into each inter-blade channel 38 at a uniform flow rate from each outlet 24b. According to such a configuration, the gas-phase refrigerant can be cooled more uniformly in the circumferential direction of the rotating shaft 25. The number of outlets 24b may be different from the number of inter-blade channels 38, or may be equal to the number of inter-blade channels 38. The outlet 24b of the injection flow path 24 may correspond to the inter-blade flow path 38 on a one-to-one basis.

When the plurality of blades 31 include a plurality of full blades and a plurality of splitter blades, the outlet 24b is located between the full blades adjacent to each other in the circumferential direction in the circumferential direction of the rotating shaft 25. Good. Or the outflow port 24b may be located between the full blade and splitter blade which adjoin in the circumferential direction. A splitter blade is a blade that is shorter than a full blade. The plurality of full blades and the plurality of splitter blades can be alternately arranged on the surface 30 p of the hub 30 along the circumferential direction of the rotation shaft 25.

In this embodiment, the rotating shaft 25 is fitted to the impeller 26 without a gap by a method such as shrink fitting or cold fitting. Thereby, it can prevent that a liquid phase refrigerant leaks from the connection part of the 1st part 241 and the 2nd part 242 of the injection flow path 24. FIG. In order to prevent leakage, a seal structure such as a seal ring may be provided.

The structure of the compressor 3 of the present disclosure can be applied to each of the multistage compressors. In each stage of the compressor, a desired effect can be obtained. For example, when the compressor 3 is a multistage compressor including a plurality of impellers, the injection flow path 24 is provided in each of the plurality of impellers, and the liquid phase refrigerant can be injected into the refrigerant flow paths of the respective stages.

Next, the operation and action of the refrigeration cycle apparatus 100 will be described.

When the refrigeration cycle apparatus 100 is left for a certain period (for example, at night), the temperature inside the refrigeration cycle apparatus 100 (refrigerant circuit 10) is generally balanced with the ambient temperature. The pressure inside the refrigeration cycle apparatus 100 is balanced to a specific pressure. When the compressor 3 is started, the pressure inside the evaporator 2 gradually decreases, and the liquid-phase refrigerant is evaporated by absorbing heat from the heat medium of the heat-absorbing circuit 12 that exchanges heat with the inside air, thereby generating a gas-phase refrigerant. . The gas phase refrigerant is sucked into the compressor 3 and compressed, and is discharged from the compressor 3. The high-pressure gas-phase refrigerant is introduced into the condenser 4, and the gas-phase refrigerant is condensed by radiating heat to the outside air or the like via the heat dissipation circuit 14, thereby generating a liquid-phase refrigerant. The liquid phase refrigerant is sent from the condenser 4 to the evaporator 2 through the return path 9.

Inside the compressor 3, liquid phase refrigerant is injected into the refrigerant flow path 40 through the main flow path 21 and the injection flow path 24. Heat exchange occurs between the vapor-phase refrigerant whose pressure is increased by the compressor 3 and the temperature rises, and the atomized liquid-phase refrigerant, and the superheated gas-phase refrigerant is continuously cooled by evaporation of the atomized liquid-phase refrigerant. Is done. Thereby, the increase in the enthalpy of the refrigerant due to the increase in the degree of superheat of the refrigerant in the compression process is continuously suppressed. The compression power required by the compressor 3 can be reduced below the compression power required for fully adiabatic isentropic compression. The work to be performed by the compressor 3 in order to increase the pressure of the refrigerant to a predetermined pressure can be greatly reduced. That is, the power consumption of the compressor 3 can be greatly saved. As a result, the efficiency of the refrigeration cycle apparatus 100 is improved.

According to this embodiment, the liquid phase refrigerant stored in the evaporator 2 is supplied to the main flow path 21 of the compressor 3 through the refrigerant supply path 11. A mist-like liquid phase refrigerant having substantially the same temperature as the temperature (saturation temperature) of the gas-phase refrigerant sucked into the compressor 3 is injected into the refrigerant flow path 40. In this case, it is possible to prevent the liquid phase refrigerant from being flash-evaporated and the vapor amount inside the compressor 3 to rapidly increase. As a result, an increase in compression power accompanying an increase in the amount of steam is suppressed. Since the increase in the compression power accompanying the increase in the amount of steam is suppressed, even if the compressor input is excessive, such as during overload operation, the above mechanism is used to reduce the compression without significantly reducing the refrigeration capacity. The effect of reducing power is obtained. Further, it is possible to prevent the compressor 3 from choking due to an increase in the amount of steam.

FIG. 20 is a flowchart showing a method for compressing a gas-phase refrigerant using the compressor 3. In step S1, gas phase refrigerant is sucked into the compressor 3. The gas-phase refrigerant is sucked by the impeller 26 and flows through the suction passage 36 of the refrigerant passage 40 in a direction parallel to the central axis O. Therefore, the flow direction of the liquid-phase refrigerant in the main channel 21 is opposite to the direction in which the gas-phase refrigerant is sucked into the compressor 3 and flows. In step S <b> 2, the sucked gas-phase refrigerant is accelerated in the compressor 3. Specifically, the gas phase refrigerant is accelerated by the impeller 26. In step S <b> 4, the liquid phase refrigerant is injected from the outlet 24 b of the injection flow path 24 toward the gas phase refrigerant existing in the refrigerant flow path 40. The injected liquid phase refrigerant is sucked into the inter-blade channel 38 of the compressor 3. Thereby, the superheat degree of a gaseous-phase refrigerant | coolant falls. The accelerated gas phase refrigerant flows from the refrigerant flow path 40 toward the diffuser 41. In step S <b> 4, the static pressure of the gas phase refrigerant is recovered in the diffuser 41.

In addition, since the compressor 3 is a speed type compressor, each process described in the flowchart is not completely separated. Each process is performed continuously.

(Modification)
FIG. 4A is a cross-sectional view of a rotating body according to a modification. FIG. 4B is a partial side view of a rotating shaft according to a modification. 4A corresponds to the cross-sectional view of FIG. The rotating body 47 of this modification includes a rotating shaft 45 and an impeller 26. The impeller 26 is attached to the rotation shaft 45 and rotates together with the rotation shaft 45. The first portion 241 of the ejection flow path 24 is connected to the second portion 242 on the side surface of the rotation shaft 45. At the connection position of the first portion 241 and the second portion 242, the angular range in which the first portion 241 exists along the circumferential direction of the rotation shaft 45 is the second portion 242 along the circumferential direction of the rotation shaft 45. Beyond the existing angle range. According to such a configuration, the connection between the first portion 241 and the second portion 242 can be easily realized. Positioning of the first portion 241 and the second portion 242 in the circumferential direction of the rotating shaft 45 is easy, and the impeller 26 is easily attached to the rotating shaft 45.

Specifically, the first portion 241 of the injection flow path 24 includes a radial portion 241a and a groove 241b. The radial direction portion 241 a is a portion located inside the rotation shaft 45. The groove 241 b is a portion provided on the side surface of the rotation shaft 45 along the circumferential direction of the rotation shaft 45. The second portion 242 is connected to the groove 241b. According to such a configuration, the liquid phase refrigerant can be supplied to each of the second portions 242 of the ejection flow path 24 at a uniform flow rate. Since the groove 241b serves as a distributor, the number of the first portions 241 (radial portions 241a) and the number of the second portions 242 may be different. In the present modification, the number of first portions 241 is smaller than the number of second portions 242. Further, since the alignment of the first portion 241 and the second portion 242 in the circumferential direction of the rotating shaft 45 is extremely easy or unnecessary, the operation of attaching the impeller 26 to the rotating shaft 45 is easy. In addition, it is not essential that the groove 241b is a complete ring shape, and the groove 241b may be arcuate.

The liquid to be ejected from the ejection flow path 24 may be a liquid other than the refrigerant. Such a liquid may be another liquid that can evaporate at the temperature of the gas phase refrigerant and cool the gas phase refrigerant.

As shown in FIG. 5, in the compressor 50 according to another modification, the injection flow path 24 extends in a direction inclined with respect to both the radial direction and the axial direction of the rotary shaft 25. The outlet 24 b of the injection flow path 24 is located between the blade 31 and the blade 31 of the impeller 26. According to such a configuration, the injected liquid-phase refrigerant can easily flow along the flow of the gas-phase refrigerant between the blades 31. As a result, it can be expected that efficient heat exchange occurs between the gas-phase refrigerant and the liquid-phase refrigerant.

As shown in FIG. 6, in the compressor 60 according to another modification, the main flow path 21 has an inlet 21 a located on the side surface of the rotating shaft 25. The connection port 28 of the housing 35 is provided at a position facing the side surface of the rotation shaft 25. Thus, the inflow port 21 a of the main channel 21 may be located on the side surface of the rotation shaft 25.

(Advantageous configuration)
The speed type compressor of the present disclosure may have the following configuration.

In order to obtain the required pressure ratio in the speed type compressor, it is necessary to increase the rotation speed and increase the peripheral speed of the impeller. The liquid-phase refrigerant exiting from the outlet of the injection flow path does not have a fixed particle size but varies with a certain particle size distribution. The small-diameter particles follow the flow of the gas-phase refrigerant and flow out of the refrigerant flow path or evaporate before flowing out.

However, the Coriolis force acts in the circumferential direction in the coordinate system that rotates with the impeller, and the Coriolis force surpasses the drag that the Coriolis force receives from the gas-phase refrigerant in a large refrigerant droplet. For this reason, the refrigerant droplets do not follow the flow of the gas-phase refrigerant, but may collide with the rear edge of the blade adjacent to the outlet and erosion may occur in the impeller.

According to the configuration described below, it is possible to prevent impeller erosion due to collision of large-sized refrigerant droplets ejected from the outlet.

FIG. 7 is a plan view obtained by projecting the impeller 26 onto a plane perpendicular to the central axis O. FIG. Curves A ₁ B ₁ and A ₂ B ₂ represent the blade root line of the first blade 311 and the blade root line of the second blade 312 on the projection view. Outlet 24b includes a first blade 311 is located on the surface of the hub 30 between the second blade 312, and is provided at a position of radius R ₁ from the central axis O as the rotational axis. The first blade 311 is a blade that is closest to the outflow port 24 b in the rotation direction opposite to the rotation direction of the rotating body 27. The second blade 312 is a blade closest to the outflow port 24 b in the rotation direction of the rotating body 27.

The “blade root line” means a boundary line between the hub 30 and each blade. Specifically, since the blade has a thickness, the hub 30 and the blade are separated by a long and narrow interface. The blade root line means a line drawn along the length direction of the boundary surface so that the boundary surface is equally divided into two in the thickness direction of the blade.

In the projection view of FIG. 7, the outlet 24b is represented by a curved surface. The radius R ₁ is represented by the distance between the central axis O and a point that bisects the curved surface.

With the central axis O as the center, the axis passing through the outlet 24b is defined as the r axis, the rotation direction angle of the rotating body 27 is defined as θ (degrees), and the rotating polar coordinate system fixed to the impeller 26 is defined. . In this specification, the rotation direction (counterclockwise direction) of the rotating body 27 is a positive direction, and the reverse rotation direction (clockwise direction) is a negative direction. The angle formed between the outflow direction of the liquid refrigerant and the r-axis is represented by an angle φ. In the example of FIG. 7, φ ≠ 0. The outflow direction of the liquid phase refrigerant means the central direction of the injection of the liquid phase refrigerant from the injection flow path 24. The rear edge B ₁ of the first blade 311 is located at a radius R ₂ from the central axis O. The angle when the angle between the line OB ₁ connecting the central axis O and the rear edge B ₁ and the r axis is measured from the r axis along the rotation direction of the rotating body 27 is represented by an angle θ _B1 . In FIG. 7, the angle θ _B1 is a negative value. The rear edge B ₂ of the second blade 312 is located at a radius R ₂ from the central axis O. The angle when the angle between the line OB ₂ connecting the center axis O and the rear edge B ₂ and the r axis is measured from the r axis along the rotation direction of the rotating body 27 is represented by an angle θ _B2 . In FIG. 7, the angle θ _B2 is a positive value.

The refrigerant droplet that has flowed out from the outlet 24b at the time 0 at the speed U flies in front of the rotating first blade 311, reaches the position of the radius R ₂ at the time t _P , and is discharged from the impeller 26. The angle when the angle between the direction OP of the position P at this time and the r axis is measured from the r axis along the rotation direction is defined as an angle θ _P. The direction OP means a line OP connecting the central axis O and the position P.

When observed in the rotating polar coordinate system, the first blade 311 is stationary, but since the centrifugal force and Coriolis force act on the droplet, the droplet follows a flight path that turns to the right while accelerating in the r-axis direction. . When θ _B1 <θ _P <θ _B2 , the refrigerant droplet is ejected from the impeller 26 without colliding with the trailing edge.

FIG. 8 represents FIG. 7 in a stationary coordinate system. When observed in a stationary coordinate system, the first blade 311 tracks a refrigerant droplet that moves linearly at a constant velocity in the direction of an angle α from the r axis at a velocity U ′. The rear edge B ₁ of the first blade 311 moves to θ ′ _B1 = θ _B1 + ωt _P. On the other hand, the trailing edge B ₂ of the second blade 312 moves to θ ′ _B2 = θ _B2 + ωt _P. The refrigerant droplet arrives at time t _P at the intersection P ′ between the straight line extension represented by the velocity U ′ and the outer edge of the impeller 26 having the radius R ₂ . Assuming that the angle of the straight line OP ′ measured from the r-axis is θ ′ _P , when θ ′ _B1 <θ ′ _P <θ ′ _B2 , the refrigerant droplet is discharged from the impeller 26 without colliding with the trailing edge.

A speed U is given by the centrifugal effect caused by the rotation of the rotating body 27. The speed U is further accelerated by attaching a nozzle having a small cross-sectional area to the outlet 24b. As the speed U decreases, the time t _P for reaching the trailing edge of the radius R ₂ increases, and the angle θ ′ _{B at} which the trailing edge moves by that time increases, so if the minimum speed U is considered. The total pressure, which is sufficient and increases due to the centrifugal effect when passing through the injection flow path 24, is given by 0.5ρω ² (R ² ₁ −R ² ₀ ). The radius R ₀ of the main flow path 21 is sufficiently smaller than the radius R ₁ and can be ignored. The total pressure that increases due to the centrifugal effect when passing through the injection flow path 24 is given by 0.5ρω ² R ² _1. . When the nozzle is not attached, the speed U is the slowest. In this case, the increase in the total pressure is just the dynamic pressure, so U = R ₁ ω holds.

Since the centrifugal force rω ² acts on the droplet refrigerant flowing out from the outlet 24b and flying in the radius r in the r direction, the following equation (1) is established from the equation of motion.

Of solution of Equation (1), t = 0 at _{_{r = R 1, u r =}} Ucosφ = R 1 ωcosφ ≒ R 1 satisfies the ω is expressed by the following equation (2).

A time t _{P at} which r = R ₂ is expressed by Expression (3).

However, the approximation of cos φ≈1 used above holds in the vicinity of φ = 0 degrees. In addition, since t _P slightly increases due to this approximation, the condition is such that the refrigerant droplets are more likely to collide with the trailing edge than in actuality.

In the rotating coordinate system, the velocity vector at the angle φ and the velocity U becomes the velocity vector of the angle α and the velocity U ′ as shown in the upper right of FIG. 8 in the stationary coordinate system. The speed U ′ is given by the following equation (4).

Here again, if U = R ₁ ω, the following equation (5) holds.

Also, the angle α is obtained by the following equation (6).

For the triangle formed by the straight line OP and the outlet 24b, the following equation (7) holds from the sine theorem.

Therefore, as can be seen from FIG. 8, equation (8) holds.

By satisfying θ ′ _B1 <θ ′ _P <θ ′ _B2 , that is, the angle φ representing the outflow direction of the injection flow path 24 satisfies the relational expression (9) below, the first blade 311 and the second blade The blade 312 does not collide with the coolant droplet.

Since the outlet 24b exists on the surface of the hub 30 near the inlet of the refrigerant flow path in the impeller 26, the ratio (R ₂ / R ₁ ) takes a value of 3-6. Further, the angle θ _B2 representing the position of the rear edge B ₂ of the second blade 312 is usually +20 degrees or less. In this range, the condition of θ ′ _{B2 on} the right side is satisfied even when φ> 90 ° that is the physical upper limit value, and thus the droplet does not collide with the second blade 312.

The lower limit value of the angle φ is determined by the collision condition regarding the first blade 311 on the left side. The lower limit value of the range of the angle φ depends on the ratio (R ₂ / R ₁ ). In the case of 3 ≦ (R ₂ / R ₁ ) ≦ 6, when R ₂ / R ₁ = 3, the lower limit value of the range of the angle φ is minimum.

FIG. 9 shows an outflow angle φ that satisfies the collision condition on the left side with respect to the angle θ _B1 that represents the position of the trailing edge B ₁ of the first blade 311. The angle θ _B1 is -40 degrees or more as a general design of the impeller 26, and at this time, φ ≧ −25 ° is a necessary condition for preventing the first blade 311 from colliding with the rear edge portion B ₁ . The upper limit value of the angle φ is determined within a range in which drilling is possible, and is, for example, 60 degrees.

As described above, the collision between the refrigerant droplet and the trailing edge can be avoided by setting the outflow direction φ ≧ −25 ° of the ejection flow path 24. As a result, erosion of the impeller 26 due to the collision of the liquid can be prevented.

(Another modification)
Next, a case where the technique of the present disclosure is applied to a multistage speed type compressor will be described. Elements common to the compressor 3 described with reference to FIG. 2 and the multistage speed compressor according to the modification are denoted by the same reference numerals, and description thereof may be omitted. The description regarding each compressor may be applied mutually as long as there is no technical contradiction. As long as there is no technical contradiction, the configurations of the compressors may be combined with each other.

The multistage compressor is designed within the range of the optimum specific speed NS that can realize highly efficient operation. Since the gas-phase refrigerant is compressed and gradually decreases in volume as it passes through the stages, in general, the pressure ratio in the subsequent stage can be set to be equal to or lower than the pressure ratio in the preceding stage. In other words, in order to reduce the degree of superheat below the fully-insulated isentropic compression, the degree of superheat to be removed in the subsequent stage may be less than or equal to the degree of superheat to be removed in the previous stage. Therefore, the injection amount of the subsequent-stage liquid phase refrigerant can be set to be equal to or less than the injection amount of the preceding-stage liquid phase refrigerant.

However, in a multistage compressor, if the radial position distance of the subsequent injection flow path is larger than the radial position distance of the previous injection flow path, the subsequent injection amount at a constant rotational angular velocity becomes excessive. Of the liquid phase refrigerant that cannot be evaporated due to the superheat of the gas phase refrigerant, there is a possibility that a liquid particle refrigerant having a large particle size that does not follow the gas phase refrigerant collides with the impeller wall surface and stays there. The latent heat of vaporization when the staying liquid-phase refrigerant evaporates due to the heat of the impeller wall does not contribute to the refrigeration capacity of the system, and the theoretical power of the compressor increases and COP decreases.

The present inventors diligently studied the above problem, and in a multistage compressor, a large-phase liquid-phase refrigerant that does not follow the gas-phase refrigerant collides with the impeller wall surface due to excessive injection of the liquid-phase refrigerant. I found a technique to prevent this.

Details will be described below.

FIG. 10 shows a cross section of a multistage speed compressor 70 according to another modification. In this modification, the compressor 70 is a two-stage compressor. However, the compressor 70 may have three or more stages.

As shown in FIG. 10, the compressor 70 is a multistage centrifugal compressor. The compressor 70 includes a rotating body 77, a housing 35, and a shroud 37. The rotating body 77 is disposed in a space surrounded by the housing 35 and the shroud 37. A motor and a bearing (not shown) for rotating the rotating body 77 may be disposed inside the housing 35.

The rotating body 77 includes a rotating shaft 25, a first impeller 26, and a second impeller 71. The first impeller 26 and the second impeller 71 are attached to the rotary shaft 25 and rotate at a high speed together with the rotary shaft 25. The first impeller 26 and the second impeller 71 may be formed integrally with the rotary shaft 25. The rotational speeds of the rotary shaft 25, the first impeller 26, and the second impeller 71 are in the range of 5000 to 100,000 rpm, for example. The rotating shaft 25 is made of a high-strength iron-based material such as S45CH. The first impeller 26 and the second impeller 71 are made of a material such as aluminum, duralumin, iron, or ceramic.

The direction of the first impeller 26 matches the direction of the second impeller 71. In other words, both the upper surface of the first impeller 26 and the upper surface of the second impeller 71 are located on the same side with respect to the direction parallel to the rotation shaft 25. However, the first impeller 26 may be attached to one end of the rotating shaft 25, and the second impeller 71 may be attached to the other end of the rotating shaft 25. In this case, the upper surface of the first impeller 26 is located on the opposite side of the upper surface of the second impeller 71 with respect to the direction parallel to the rotation shaft 25. The back surface of the first impeller 26 and the back surface of the second impeller 71 face each other.

The space around the first impeller 26 and the second impeller 71 includes a refrigerant flow path 40, a refrigerant flow path 80, a first diffuser 41, a second diffuser 51, a spiral chamber 42, and a return channel 79. The refrigerant channel 40 and the refrigerant channel 80 are located around the rotating body 27 and are channels through which a gas phase refrigerant to be compressed flows. The refrigerant flow path 40 includes a suction flow path 36 and a plurality of inter-blade flow paths 38. The refrigerant flow path 80 includes a suction flow path 76 and a plurality of inter-blade flow paths 78. When the first impeller 26 and the second impeller 71 rotate, the rotational speed is given to the gas-phase refrigerant flowing through each of the plurality of inter-blade passages 38 and the inter-blade passages 78.

The first diffuser 41 is provided so as to surround the first impeller 26. The second diffuser 51 is provided so as to surround the second impeller 71. The first diffuser 41 is a flow path for guiding the gas-phase refrigerant accelerated in the rotation direction by the first impeller 26 to the return channel 79. The second diffuser 51 is a flow path for guiding the gas-phase refrigerant accelerated in the rotation direction by the second impeller 71 to the spiral chamber 42. The cross-sectional area of the flow path of the first diffuser 41 increases from the refrigerant flow path 40 toward the return channel 79. The cross-sectional area of the flow path of the second diffuser 51 increases from the refrigerant flow path 80 toward the spiral chamber 42. This structure decelerates the flow velocity of the gas-phase refrigerant accelerated by the first impeller 26 and the second impeller 71 and increases the pressure of the gas-phase refrigerant. The 1st diffuser 41 and the 2nd diffuser 51 are vaneless diffusers comprised by the flow path extended in a radial direction, for example. In order to effectively increase the pressure of the refrigerant, the first diffuser 41 and the second diffuser 51 may be a vane diffuser having a plurality of vanes and a plurality of flow paths partitioned by them.

The return channel 79 is a flow path that guides the gas-phase refrigerant compressed by passing through the first impeller 26 to the second impeller 71. The return channel 79 extends inward from the first diffuser 41 toward the suction flow path 76.

The spiral chamber 42 is a spiral space in which the gas-phase refrigerant that has passed through the second diffuser 51 is collected. The compressed gas-phase refrigerant is guided to the outside of the compressor 70 (discharge pipe 8) via the spiral chamber 42. The cross-sectional area of the spiral chamber 42 is enlarged along the circumferential direction, whereby the flow rate and angular momentum of the gas-phase refrigerant in the spiral chamber 42 are kept constant.

The shroud 37 covers the first impeller 26 and the second impeller 71, and defines the refrigerant flow path 40, the first diffuser 41, the second diffuser 51, the spiral chamber 42, and the return channel 79. The shroud 37 is made of an iron-based material or an aluminum-based material. Examples of the iron-based material include FC250, FCD400, and SS400. ACD12 etc. are mentioned as an aluminum-type material.

The housing 35 serves as a casing that accommodates various components of the compressor 70. A spiral chamber 42 is formed by combining the housing 35 and the shroud 37. The housing 35 can be made of the iron-based material or the aluminum-based material described above. When the diffuser is a vaned diffuser, the plurality of vanes can also be made of the iron-based material or aluminum-based material described above.

The main flow path 21, the first injection flow path 24, and the second injection flow path 74 are provided inside the rotating body 77. The main flow path 21 extends in the axial direction of the rotating body 27 inside the rotating body 27. Specifically, the main flow path 21 is provided inside the rotation shaft 25 and extends in the axial direction of the rotation shaft 25. The first injection flow path 24 branches from the main flow path 21 inside the first impeller 26 and extends from the main flow path 21 to the refrigerant flow path 40. The second injection channel 74 branches from the main channel 21 inside the second impeller 71 and extends from the main channel 21 to the refrigerant channel 80. The main channel 21 is connected to the evaporator 2 through the refrigerant supply channel 11. The liquid refrigerant introduced from the refrigerant supply path 11 located outside the rotating body 27 flows through the main flow path 21. The first injection flow path 24 is a flow path that guides the liquid phase refrigerant from the main flow path 21 to the refrigerant flow path 40. The second injection channel 74 is a channel that guides the liquid phase refrigerant from the main channel 21 to the refrigerant channel 80.

The liquid phase refrigerant is supplied from the evaporator 2 to the main flow path 21 through the refrigerant supply path 11. The liquid-phase refrigerant is pressurized by centrifugal force and injected toward the refrigerant flow path 40 and the refrigerant flow path 80 inside the compressor 70 through the main flow path 21, the first injection flow path 24 and the second injection flow path 74. Is done. When the liquid-phase refrigerant contacts the gas-phase refrigerant in the refrigerant channel 40 and the refrigerant channel 80, heat exchange occurs between the liquid-phase refrigerant and the gas-phase refrigerant, and the superheated state is caused by sensible heat or latent heat of vaporization of the liquid-phase refrigerant. The gas phase refrigerant is continuously cooled.

FIG. 11 shows a cross section of the first impeller 26 at a position including the outflow port 24b and a cross section of the second impeller 71 at a position including the outflow port 74b. The opening area of the outlet 24b of the first injection channel 24 is S ₁ , the opening area of the outlet 74b of the second injection channel 74 is S ₂ , and the radial distance from the central axis O of the rotating body 77 to the outlet 24b is set. R ₁ and the radial distance from the central axis O of the rotating body 77 to the outlet 74b are defined as R ₂ . At this time, the compressor 70 satisfies the relationship of (R ₂ / R ₁ ≦ S ₁ / S ₂ ).

The opening area S ₁ may be a channel cross-sectional area of the first injection channel 24. The opening area S ₂ may be a channel cross-sectional area of the second injection channel 74. The radial distance R ₁ means the distance from the central axis O to the center or the center of gravity of the outlet 24b. The radial distance R ₂ means a distance from the central axis O to the center or the center of gravity of the outlet 74b.

As shown in FIG. 11, in the case of R ₁ ≦ R ₂ , for example, the radius of the hub 30 of the first impeller 26, that is, the radial distance R ₁ of the outlet 24b is decreased to increase the inlet area of the gas phase refrigerant. Thus, high efficiency operation can be performed by reducing the Mach number at the entrance.

As shown in FIG. 12, a centrifugal force acts on the liquid refrigerant inside the main flow path 21, and a pressure gradient dp / dr is generated in the radial direction so as to balance the centrifugal force. It is represented by the following formula (10).

If the equation (10) is integrated from a radius of zero to r, the pressure is expressed as P ₁ = (ρω ² r ² ) / 2. The supply static pressure Ps of the liquid phase refrigerant is set to zero. Further, the pressure head due to gravity is negligibly small as compared with the pressure head due to centrifugal force, and is therefore omitted.

Suppose the outflow velocity is v and the cross-sectional area of the outlet is A. With regard to the liquid phase refrigerant existing inside the injection flow path, considering a minute columnar portion with a thickness dr in the injection direction, the acceleration in the injection direction is a = vdv / dr from a = dv / dt and dt = dr / v. expressed.

Since the force acting in the injection direction is a centrifugal force (ρAω ² rdr) and a force −A (dp / dr) dr due to the pressure difference before and after the minute columnar portion, the equation of motion in the injection direction is expressed by the following equation (11). It is represented by

If the equation (11) is integrated, the following equation (12) is obtained.

When the inlet of the injection flow path is represented by the subscript “1” and the outlet of the injection flow path is represented by the subscript “2”, the following expression (13) is obtained.

Here, if v ₁ = 0 and P ₁ = (ρω ² r ² ) / 2, the outflow velocity v ₂ is expressed by the following equation (14).

The flow rate Q is represented by the product of the opening area S (S = the number N of the injection channels × the cross-sectional area A of the outlet) and the outflow velocity v ₂ . Assuming that the liquid phase refrigerant flows out at a theoretical flow rate ignoring the loss, the flow rate Q is expressed by the following equation (15).

Actually, since there are various losses, Equation (15) can be defined as Equation (16) considering the flow coefficient C.

Here, P ₂ is the vapor pressure of the gas-phase refrigerant flowing through the refrigerant flow path. Since P ₂ is negligibly small compared to the pressure due to centrifugal force and can be omitted, Q = CSωR is established.

That is, the injection flow rate Q is proportional to the product of the opening area S of the outlet, the rotational angular velocity ω, and the radial distance R from the central axis to the outlet.

In the multistage compressor 70, the gas-phase refrigerant is compressed as it passes through the stages, and the volume gradually decreases. Therefore, the pressure ratio in the subsequent stage can be set to be equal to or lower than the pressure ratio in the preceding stage. In other words, in order to reduce the degree of superheat below the fully-insulated isentropic compression, the degree of superheat to be removed in the subsequent stage may be less than or equal to the degree of superheat to be removed in the previous stage. Therefore, the injection amount of the subsequent-stage liquid phase refrigerant can be set to be equal to or less than the injection amount of the preceding-stage liquid phase refrigerant.

That is, (the injection amount Q1 of the liquid refrigerant at the front stage) ≧ (the injection amount Q2 of the liquid refrigerant at the rear stage) can be established.

As described above, when the relationship of S ₁ × R ₁ ≧ S ₂ × R ₂ , that is, R ₂ / R ₁ ≦ S ₁ / S ₂ is satisfied, the rotational angular velocity ω is constant, so the second impeller 71 The injection amount from the injection flow path 74 is equal to or less than the injection amount from the injection flow path 24 of the first impeller 26.

This ensures that the liquid refrigerant injected in an amount commensurate with the degree of superheat to be removed evaporates in the refrigerant flow path.

Therefore, in the multistage compressor 70, it is possible to prevent the liquid phase refrigerant having a large particle diameter that does not follow the gas phase refrigerant from colliding with the impeller wall surface due to excessive injection of the liquid phase refrigerant.

(Another modification)
Even in a multistage compressor, there is a problem of impeller erosion due to refrigerant droplets.

When the amount of liquid phase refrigerant necessary to remove the superheat generated in each stage of the multistage compressor is injected into the refrigerant flow path around the first stage impeller, the liquid present around the first stage impeller The amount of drops is excessive. As a result, the collision probability of the refrigerant droplets on the impeller is increased, and the risk of erosion of the impeller is increased.

In the compressor 70 described with reference to FIG. 10, the injection flow path 24 and the injection flow path 74 are provided in each of the first impeller 26 and the second impeller 71. Although this configuration is effective in preventing impeller erosion, there remains room for improvement.

As a result of further studies by the present inventors, a configuration has been found in which a more appropriate amount of liquid-phase refrigerant can be injected in a multistage compressor. Hereinafter, the configuration will be described.

FIG. 13 shows a cross section of a multistage speed compressor 90 according to another modification. The difference between the compressor 70 described with reference to FIG. 10 and the compressor 90 of this modification is in the number and position of the injection flow paths.

As shown in FIG. 13, the main flow path 21, the first injection flow path 24, the downstream injection flow path 32, and the second injection flow path 74 are provided inside the rotating body 77. The main flow path 21 extends in the axial direction of the rotating body 77 inside the rotating body 77. Specifically, the main flow path 21 is provided inside the rotation shaft 25 and extends in the axial direction of the rotation shaft 25.

The first injection flow path 24 is located inside the first impeller 26, branches from the main flow path 21, and extends from the main flow path 21 to the refrigerant flow path 40. The first injection flow path 24 is located upstream of the inter-blade flow path 38 in the flow direction of the gas-phase refrigerant. The first injection flow path 24 is provided on the upstream side of the upstream end 31 t of the blade of the first impeller 26. By injecting the liquid phase refrigerant from the first injection channel 24 toward the refrigerant channel 40, only the amount of the liquid phase refrigerant necessary for removing the degree of superheat generated in the first impeller 26 can be supplied. The first injection flow path 24 may be provided on the downstream side of the upstream end 31t of the blade of the first impeller 26.

The downstream injection flow path 32 is located inside the first impeller 26, branches from the main flow path 21, and extends from the main flow path 21 to the refrigerant flow path 40. The downstream injection flow path 32 is located downstream of the first injection flow path 24 in the flow direction of the gas-phase refrigerant. The central axis of the downstream injection flow path 32 intersects the inlet of the first diffuser 41. The outlet 32 b of the downstream injection flow path 32 is located on the surface of the hub 30 of the first impeller 26. The downstream injection flow path 32 penetrates the hub 30 in the radial direction of the rotation shaft 25. The outlet 32 b faces the inlet of the first diffuser 41.

The amount of liquid-phase refrigerant necessary to remove the degree of superheat generated by the second impeller 71 is injected through the downstream injection flow path 32. The liquid refrigerant injected from the downstream injection flow path 32 partially evaporates in the first diffuser 41. The second impeller 71 sucks only the amount of liquid-phase refrigerant necessary to remove the degree of superheat generated by the second impeller 71. The amount of refrigerant droplets existing in each of the refrigerant flow path 40 around the first impeller 26 and the refrigerant flow path 80 around the second impeller 71 decreases. As a result, the collision probability of the refrigerant droplets on the first impeller 26 and the second impeller 71 is reduced, and the erosion risk of the first impeller 26 and the second impeller 71 is reduced.

The second injection flow path 74 is located inside the second impeller 71 and branches from the main flow path 21 and extends from the main flow path 21 to the refrigerant flow path 80. The central axis of the second injection flow path 74 intersects the inlet of the second diffuser 51. The outlet 74 b of the second injection flow path 74 is located on the surface of the hub 33 of the second impeller 71. The second injection flow path 74 passes through the hub 33 in the radial direction of the rotation shaft 25. The outlet 74 b faces the inlet of the second diffuser 51. According to the second injection flow path 74, heat can also be taken from the gas-phase refrigerant when pressure recovery is performed in the second diffuser 51. This configuration is also effective for a multistage speed type compressor having three or more stages.

“The central axis of the injection flow path” means an axis that passes through the center or the center of gravity of the cross section of the injection flow path and extends parallel to the injection flow path. “Diffuser entrance” means the entrance to the space acting as a diffuser.

The liquid phase refrigerant is supplied from the evaporator 2 or the condenser 4 to the main flow path 21 through the refrigerant supply path 11. The first injection flow path 24, the downstream injection flow path 32, and the second injection flow path 74 are flow paths that lead the liquid phase refrigerant from the main flow path 21 to the refrigerant flow path 40 and the refrigerant flow path 80. The liquid phase refrigerant is pressurized by centrifugal force, and the refrigerant flow path 40 and the refrigerant inside the compressor 90 are passed through the main flow path 21, the first injection flow path 24, the downstream injection flow path 32, and the second injection flow path 74. Injected toward the flow path 80. When the liquid-phase refrigerant contacts the gas-phase refrigerant in the refrigerant channel 40 and the refrigerant channel 80, heat exchange occurs between the liquid-phase refrigerant and the gas-phase refrigerant, and the superheated state is caused by sensible heat or latent heat of vaporization of the liquid-phase refrigerant. The gas phase refrigerant is continuously cooled.

(Another modification)
FIG. 14 shows a compressor 3a obtained by adding a motor 16 to the compressor 3 described with reference to FIG. In addition to the configuration of the compressor 3, the compressor 3 a further includes a motor 16 attached to the rotary shaft 25. The motor 16 is disposed inside the housing 35. The motor 16 has a rotor 16a and a stator 16b. A rotor 16 a is fixed to the rotation shaft 25. When the motor 16 is driven, the rotating body 27 rotates.

Bearings

18 a and 18 b that support the rotating shaft 25 are disposed on both sides of the motor 16.

The liquid phase refrigerant in the main flow path 21 provided inside the rotary shaft 25 is heated by the exhaust heat of the motor 16. Since the liquid refrigerant is centrifugally pressurized in the injection flow path 24 inside the rotating body 27 rotating at a high speed of the compressor 3a, the power of the motor 16 is further increased and the temperature increase range is increased. The amount of heat generated by the rotor 16a of the motor 16 is, for example, about 0.8 kW when the refrigerating capacity is 880 kW as a rated condition. In particular, in the case of a high load operation condition, the rotational speed of the compressor 3a increases, and the amount of exhaust heat of the motor 16 increases according to the rotational speed. As a result, the liquid-phase refrigerant may evaporate inside the main channel 21 and the gas-phase refrigerant may stay. In this case, the main flow path 21 is blocked by the gas phase refrigerant, and the motor 16 cannot be continuously cooled without the liquid phase refrigerant flowing therethrough, and the efficiency of the motor 16 is reduced.

The present modification solves the above-mentioned problem, and reduces the compressor power due to the increase in enthalpy during compression, while preventing the blockage of the flow path due to the evaporation of the liquid-phase refrigerant inside the main flow path. I will provide a. At the same time, the motor is continuously cooled to improve the efficiency of the motor.

FIG. 15 shows a cross section of the compressor 3b that can solve the problem by the heat generated by the motor 16. The compressor 3b includes a motor 16 having a rotor 16a and a stator 16b. The rotor 16 a is fixed to the rotary shaft 25 between the impeller 26 and the bearing 18 b in the axial direction of the rotary shaft 25. The rotor 16a is made of a steel material such as a silicon nitride steel plate. The stator 16b is disposed so as to surround the rotor 16a in the circumferential direction of the rotation shaft 25. A rotating torque is generated in the rotor 16a by the rotating magnetic field induced by the stator 16b. Thereby, the rotating shaft 25 and the impeller 26 are driven to rotate at high speed.

The buffer chamber 35 h is provided in contact with the inflow port 21 a and communicates with the main flow path 21.

Next, the buffer chamber 35h will be described in detail.

As shown in FIG. 15, the compressor 3 b further includes a supply tank 20 and a pressurizing pump 19. The buffer chamber 35 h is connected to the refrigerant supply path 22 provided outside the housing 35. The refrigerant supply path 22 communicates the buffer chamber 35 h and the supply tank 20. The refrigerant supply path 22 is provided with a pressure pump 19 for pressure-feeding the liquid-phase refrigerant stored in the supply tank 20 to the buffer chamber 35h. The temperature of the liquid phase refrigerant in the supply tank 20 is, for example, 35 ° C.

Specific examples of the supply tank 20 include a condenser, an evaporator, and other buffer tanks.

The pressurizing pump 19 is a pump for increasing the pressure of the liquid refrigerant in the supply tank 20 and supplying it to the buffer chamber 35h. The supply pressure of the liquid phase refrigerant is, for example, about 25 to 100 kPa. The pressurizing pump 19 may be a positive displacement pump or a speed pump. The positive displacement pump is a pump that sucks and discharges a liquid phase refrigerant according to a change in volume and raises the pressure of the refrigerant. Examples of the positive displacement pump include a rotary pump, a screw pump, a scroll pump, a vane pump, and a gear pump. A speed type pump is a pump that gives momentum to a liquid phase refrigerant and raises the pressure of the refrigerant by decelerating the speed of the liquid phase refrigerant. Examples of the speed pump (turbo pump) include a centrifugal pump, a mixed flow pump, and an axial flow pump. Moreover, a cascade pump, a hydrocera pump, etc. may be used. The pressurizing pump 19 includes a motor driven by a pump controller such as an inverter, and may be a mechanism capable of changing the rotation speed. The supply pressure of the pressure pump 19 is adjusted in consideration of the pressure loss of the main flow path 21 and the refrigerant supply path 22. The liquid-phase refrigerant is pumped so that the flow rate of the liquid-phase refrigerant necessary for cooling according to the operating conditions is increased to a pressure higher than the pressure evaporating inside the main flow path 21.

The liquid-phase refrigerant that cools the gas-phase refrigerant is liquid-phase refrigerant stored in the supply tank 20, supplied from the inlet 21 a via the buffer chamber 35 h, and branched to the injection flow path 24 through the main flow path 21 of the rotating shaft 25. To do. The liquid-phase refrigerant is centrifugally pressurized in the injection flow path 24 inside the rotating body 27 that rotates at high speed, injected into the refrigerant flow path 40 from the outlet 24b, and sucked together with the gas-phase refrigerant sucked into the compressor 3b. The When the refrigerating capacity is 880 kW as the rated condition, the injection amount of the liquid-phase refrigerant necessary for removing the heat generated in the compression process is, for example, 0.034 kg / s. For example, if the diameter of the injection flow path 24 is 0.13 mm and the number of ports is 16, the liquid phase refrigerant is injected from the outlet 24 b into the refrigerant flow path 40 with a pressure of about 1.4 MPa through the injection flow path 24. The liquid phase refrigerant continues to be supplied from the supply tank 20 and is pumped to the buffer chamber 35h by the pressurizing pump 19 in addition to suction by centrifugal pressurization.

As described above, the liquid-phase refrigerant is centrifugally pressurized in the injection flow path 24 inside the rotating body 27 rotating at high speed and injected into the refrigerant flow path 40, so that the superheated gas-phase refrigerant is continuously cooled. Is done. The liquid refrigerant is pressurized by the pressurizing pump 19 when passing through the refrigerant supply path 22, and since the pressure of the liquid refrigerant increases and the boiling point rises, it is difficult to evaporate inside the main flow path 21, It becomes possible to suppress road blockage. In addition, since the motor 16 can be reliably cooled, the efficiency of the motor 16 is also improved.

Specifically, when the refrigerating capacity is 880 kW as the rated condition, the heat generation amount of the motor 16 is about 0.8 kW, and the injection amount of the liquid phase refrigerant necessary for removing the heat generated in the compression process is, for example, 0.034 kg. / S. If the temperature of the liquid phase refrigerant in the supply tank 20 is 35 ° C. (4.25 kPa), the temperature after passing through the main flow path 21 is 40.46 ° C. (7.57 kPa). The compressor 3b is provided at a height of, for example, 1.5 m with reference to the outlet of the supply tank 20. Considering the pressure loss of the main flow path 21 and the refrigerant supply path 22 of the compressor 3b, in order to prevent the liquid phase refrigerant from evaporating in the main flow path 21, the liquid phase refrigerant supplied from the supply tank 20 is, for example, 22. Boosting of 3 kPa or more is required. Therefore, when the supply pressure of the pressurizing pump 19 is 22.3 kPa or more, the liquid-phase refrigerant whose pressure has been increased to be equal to or higher than the pressure for evaporation is supplied. For this reason, the liquid refrigerant is unlikely to evaporate in the main flow path 21, and the flow path blockage due to the vapor can be suppressed.

FIG. 16 shows a cross section of a compressor 3c according to another modification. In the compressor 3 c, the buffer chamber 35 h is connected to the refrigerant supply path 22. The refrigerant supply path 22 communicates the buffer chamber 35 h and the supply tank 20. The refrigerant supply path 22 is provided with a pressure pump 19 for pressure-feeding the liquid-phase refrigerant stored in the supply tank 20 to the buffer chamber 35h, and a heat exchanger 23 for exchanging heat with an external heat source.

The compressor 3c is different from the compressor 3b shown in FIG. 15 in that it further includes a heat exchanger 23.

The refrigerant supply path 22 is a flow path connected to the buffer chamber 35 h and the pressurizing pump 19. The heat exchanger 23 is provided in the refrigerant supply path 22 between the buffer chamber 35 h and the pressurizing pump 19.

The temperature of the liquid phase refrigerant in the supply tank 20 is, for example, 35 ° C. The inflow temperature of the heat exchanger 23 is, for example, 35 ° C., and the outflow temperature is, for example, 30 ° C.

As described above, since the liquid phase refrigerant is cooled by the heat exchanger 23 provided in the refrigerant supply path 22, the liquid refrigerant in the supercooled state is supplied to the main flow path 21, and the liquid phase refrigerant is It is difficult to evaporate inside the main channel 21. Thereby, especially when the rotational speed of the compressor 3c increases under a high load operation condition and the amount of exhaust heat of the motor 16 is large, it is possible to suppress the blockage of the flow path due to steam.

The structure of the heat exchanger 23 is not particularly limited. As the heat exchanger 23, a fin tube heat exchanger, a plate heat exchanger, a double tube heat exchanger, or the like can be used. An external heat source that heat-exchanges the liquid-phase refrigerant and cools the liquid-phase refrigerant in the heat exchanger 23 is not particularly limited. Air, cooling water, or the like can be used as an external heat source.

(Embodiment 2)
FIG. 17 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present disclosure. Elements that are common between the first embodiment and other embodiments are denoted by the same reference numerals, and description thereof may be omitted. The description regarding each embodiment may be applied mutually as long as there is no technical contradiction. As long as there is no technical contradiction, the embodiments may be combined with each other.

As shown in FIG. 17, in the refrigeration cycle apparatus 102 according to the second embodiment, the refrigerant supply path 11 connects the condenser 4 and the compressor 3. In the compressor 3, the liquid phase refrigerant injected into the refrigerant flow path 40 through the main flow path 21 and the injection flow path 24 is a liquid phase refrigerant stored in the condenser 4. Also in this modification, the effect which reduces compression power is acquired by the mechanism demonstrated in Embodiment 1. FIG. That is, the liquid phase refrigerant to be supplied to the main flow path 21 inside the compressor 3 is not limited to the liquid phase refrigerant stored in the evaporator 2. As long as it exists in the refrigerant circuit 10, the liquid phase refrigerant can be supplied to the main flow path 21. For example, when there is a buffer tank that is connected to the evaporator 2 or the condenser 4 and stores liquid phase refrigerant, the refrigerant supply path 11 is configured so that the liquid phase refrigerant is supplied from the buffer tank to the main flow path 21. The buffer tank and the compressor 3 may be connected. Further, the refrigerant supply path 11 may be branched from the return path 9. In other words, the return path 9 may also serve as a part of the refrigerant supply path 11. In this case, the refrigerant supply path 11 guides the liquid phase refrigerant from the condenser 4 to the main flow path 21.

According to this modification, the compressor 3 sucks the liquid phase refrigerant having a temperature higher than the temperature (saturation temperature) of the gas-phase refrigerant sucked into the compressor 3. In this case, an effect of reducing the compression power can be obtained by the mechanism described in the first embodiment while preventing the gas-phase refrigerant from being excessively cooled and condensing inside the compressor 3.

The refrigeration cycle apparatus 102 may include a reserve tank that stores liquid phase refrigerant. The spare tank is connected to the condenser 4, for example. Liquid phase refrigerant is transferred from the condenser 4 to the spare tank. The refrigerant supply path 11 connects the auxiliary tank and the compressor 3 so that liquid refrigerant is supplied from the auxiliary tank to the compressor 3.

Instead of the compressor 3, the

other compressors

3a, 3b, 3c, 50, 60, 70 and 90 described above can be used.

(Embodiment 3)
FIG. 18 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 3 of the present disclosure. As shown in FIG. 18, the refrigeration cycle apparatus 104 includes an ejector 53, a buffer tank 52, and a heat exchanger 23 as an alternative to the condenser 4.

The operation and action of the refrigeration cycle apparatus 104 configured as described above will be described below.

The gas phase refrigerant compressed and discharged by the compressor 3 is sucked into the ejector 53. In addition, liquid phase refrigerant is stored in the buffer tank 52, and the liquid phase refrigerant in the buffer tank 52 radiates heat in the heat exchanger 23 and is supplied to the ejector 53. In the ejector 53, the gas-phase refrigerant received from the compressor 3 and the liquid-phase refrigerant received from the heat exchanger 23 are mixed. The refrigerant is compressed in a two-phase state and supplied to the buffer tank 52 as a high-temperature liquid-phase refrigerant or a gas-liquid two-phase refrigerant. That is, in the ejector 53, the gas-phase refrigerant is condensed by being pressurized in a two-phase state. The liquid refrigerant radiates heat with the heat exchanger 23. As a result, the ejector 53, the buffer tank 52, and the heat exchanger 23 function as an alternative to the condenser 4. The temperature of the liquid phase refrigerant in the buffer tank 52 is, for example, 38.5 ° C. The inflow temperature of the heat exchanger 23 is 38.5 ° C., for example, and the outflow temperature is 33.5 ° C., for example.

The liquid refrigerant in the buffer tank 52 is pumped to the heat exchanger 23 by the pressurizing pump 19. The flow path of the liquid-phase refrigerant on the discharge side of the pressurizing pump 19 is bifurcated. One communicates with the heat exchanger 23 and the other communicates with the buffer chamber 35 h of the compressor 3. That is, the flow path that connects the branch point of the flow path of the liquid-phase refrigerant on the discharge side of the pressurizing pump 19 and the buffer chamber 35 h is the refrigerant supply path 22. The supply pressure of the pressure pump 19 is, for example, about 250 kPa.

As described above, the liquid-phase refrigerant is centrifugally pressurized in the injection flow path 24 inside the rotating body 27 rotating at high speed and injected into the refrigerant flow path 40, so that the superheated gas-phase refrigerant is continuously cooled. Is done. The liquid refrigerant is pressurized by the pressurizing pump 19 when passing through the refrigerant supply path 22, and the pressure of the liquid refrigerant rises to raise the boiling point. It becomes possible to suppress road blockage.

(Embodiment 4)
FIG. 19 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 4 of the present disclosure. As shown in FIG. 19, the refrigeration cycle apparatus 106 includes an ejector 53, a buffer tank 52, and a heat exchanger 23 as an alternative to the condenser 4.

The operation and action of the refrigeration cycle apparatus 106 configured as described above will be described below.

The liquid phase refrigerant in the buffer tank 52 is pumped to the heat exchanger 23 by the pressurizing pump 19, dissipates heat by the heat exchanger 23, and is supplied to the ejector 53. The flow path of the liquid phase refrigerant on the outflow side of the heat exchanger 23 is bifurcated. One communicates with the ejector 53 and the other communicates with the buffer chamber 35 h of the compressor 3. That is, the flow path that connects the branch point of the flow path of the liquid-phase refrigerant on the outflow side of the heat exchanger 23 and the buffer chamber 35 h is the refrigerant supply path 22. The temperature of the liquid phase refrigerant in the buffer tank 52 is, for example, 38.5 ° C. The inflow temperature of the heat exchanger 23 is 38.5 ° C., for example, and the outflow temperature is 33.5 ° C., for example.

As described above, since the liquid phase refrigerant is cooled by the heat exchanger 23 provided in the refrigerant supply path 22, the liquid refrigerant in the supercooled state is supplied to the main flow path 21, and the liquid phase refrigerant is It is difficult to evaporate inside the main channel 21. Thereby, especially when the rotation speed of the compressor 3 increases under a high load operation condition and the amount of exhaust heat of the motor 16 is large, blockage of the flow path due to steam can be suppressed.

The refrigeration cycle apparatus disclosed in this specification is useful for an air conditioner, a chiller, a heat storage device, and the like. An air conditioner is used for central air conditioning of a building, for example. Chillers are used, for example, in process cooling applications.

2

Evaporators

3, 3a, 3b, 3c, 50, 60, 70, 90 Compressor 4 Condenser 6 Suction pipe 8 Discharge pipe 9 Return path 10

Refrigerant circuits

11, 22 Refrigerant supply path 12 Heat absorption circuit 14 Heat radiation circuit 16 Motor 18 Bearing 19 Pressure pump 20 Supply tank 21 Main flow path 21a Inlet 23 Heat exchanger 24 Injection flow path (first injection flow path)
24b, 32b,

74b Outlet

25, 45 Rotating shaft 25c End face 26 Impeller (first impeller)

26t Upper surface

27, 47, 77 Rotating body 28 Connection port 29

Seal

30, 33 Hub 30p Hub surface 31 Blade 31t Blade upstream end 32 Downstream injection flow path 35 Housing

35h Buffer chamber

36, 76 Suction flow path 37

Shroud

38, 78

Inter-blade channel

40, 80 Refrigerant channel 41 Diffuser (first diffuser)
42 Swirl chamber 51 Second diffuser 52 Buffer tank 53 Ejector 71 Second impeller 74 Second injection flow path 79

Return channel

100, 102, 104, 106 Refrigeration cycle device 241 First part 241a Radial part 241b Groove 242 Second part 311 First blade 312 Second blade

Claims

A rotating body including a rotating shaft and at least one impeller;
A refrigerant passage located around the rotating body and through which a gas-phase refrigerant flows;
A main flow path that extends in the axial direction of the rotating body inside the rotating body and through which a liquid-phase refrigerant flows;
An injection flow path that is located inside the rotating body, extends from the main flow path to the refrigerant flow path, branches from the main flow path, and guides the liquid-phase refrigerant from the main flow path to the refrigerant flow path;
Equipped with a speed compressor.
The impeller has a hub and a blade fixed to the hub;
The injection flow path has an outlet facing the refrigerant flow path;
The outlet is positioned upstream of the upstream end of the blade in the flow direction of the gas-phase refrigerant.
The speed type compressor according to claim 1.
The impeller has a hub and a blade fixed to the hub;
The injection flow path has an outlet located on the surface of the hub and penetrates the hub in the radial direction of the rotation shaft.
The speed type compressor according to claim 1 or 2.
The injection flow path is positioned between the first part and the refrigerant flow path, the first part extending in the radial direction of the rotary shaft from the main flow path inside the rotary shaft. Including, and
The speed type compressor according to any one of claims 1 to 3.
The number of the injection flow paths having the first part and the second part is two or more.
The speed type compressor according to claim 4.
The first portion includes a groove provided on a side surface of the rotary shaft along a circumferential direction of the rotary shaft,
The second portion is connected to the groove;
The speed type compressor according to claim 4 or 5.
The main flow path has an inflow port located on an end face of the rotating shaft,
The speed type compressor according to any one of claims 1 to 6.
A supply tank in which the liquid-phase refrigerant is stored;
A buffer chamber in contact with the inlet to the main flow path;
A pressure pump that pumps the liquid-phase refrigerant from the supply tank to the buffer chamber via a refrigerant supply path connected to the buffer chamber;
The speed type compressor according to any one of claims 1 to 7, further comprising:
A heat exchanger for exchanging heat with an external heat source;
The refrigerant supply path is a flow path connected to the buffer chamber and the pressure pump,
The heat exchanger is provided in the refrigerant supply path between the buffer chamber and the pressure pump.
The speed type compressor according to claim 8.
The impeller has a hub and a plurality of blades fixed to the hub,
The injection flow path has an outlet facing the refrigerant flow path;
The blade that is closest to the outlet in a rotational direction opposite to the rotational direction of the rotating body is defined as a first blade;
In the projection obtained by projecting the blade root line of the first blade on a plane perpendicular to the rotation axis, the outermost peripheral part of the blade root line is defined as a first trailing edge,
A line extending radially from the central axis of the rotating body through the outlet is defined as an r-axis;
When the rotation direction of the rotating body is defined as a positive direction,
An angle when the angle formed between the r axis and the line connecting the first trailing edge portion and the central axis is measured from the r axis along the rotation direction of the rotating body is −40 degrees or more;
The ratio of the distance from the central axis of the rotating body to the first trailing edge with respect to the distance from the central axis of the rotating body to the outlet is 3 or more,
In the projection obtained by projecting the outflow direction of the liquid refrigerant injected from the outlet onto the plane perpendicular to the rotation axis, the angle formed between the outflow direction of the liquid refrigerant and the r axis The angle when measured from the r-axis along the rotation direction of the rotating body is −25 degrees or more,
The speed type compressor according to any one of claims 1 to 9.
The at least one impeller includes a first impeller and a second impeller;
The injection flow path is provided in each of the first impeller and the second impeller,
The opening area of the outlet of the injection passage provided on the first impeller is defined as S 1,
The opening area of the outlet of the injection passage provided on the second impeller is defined as S 2,
R 1 is defined as a distance from the central axis of the rotating body to the outlet of the injection flow path provided in the first impeller,
When the distance from the center axis of the rotary body to said outlet of said injection passage provided on the second impeller is defined as R 2,
The relationship of (R 2 / R 1 ≦ S 1 / S 2 ) is satisfied,
The speed type compressor according to any one of claims 1 to 10.
The at least one impeller includes a first impeller and a second impeller;
The speed compressor further includes a first diffuser facing the first impeller,
The first impeller is provided inside the first impeller, and is provided with a downstream injection passage that branches from the main passage and extends from the main passage to the refrigerant passage,
The downstream injection flow path is located downstream of the injection flow path in the flow direction of the gas-phase refrigerant,
The central axis of the downstream injection flow path intersects the inlet of the first diffuser,
The speed type compressor according to any one of claims 1 to 11.
The speed compressor further includes a second diffuser facing the second impeller,
The second impeller is provided with a second injection flow path that is located inside the second impeller, branches from the main flow path, and extends from the main flow path to the refrigerant flow path,
The central axis of the second injection flow path intersects the inlet of the second diffuser,
The speed type compressor according to claim 12.
An evaporator,
The speed type compressor according to any one of claims 1 to 13,
A condenser,
A refrigeration cycle apparatus comprising:
The evaporator stores a liquid phase refrigerant therein,
The condenser stores liquid phase refrigerant therein,
The refrigeration cycle apparatus further includes a refrigerant supply path that guides the liquid phase refrigerant stored in the evaporator or the liquid phase refrigerant stored in the condenser to the speed compressor.
The refrigeration cycle apparatus according to claim 14.
A compression method using a speed type compressor,
The speed compressor includes a rotating body including a rotating shaft and an impeller, and a refrigerant flow path that is positioned around the rotating body and that flows the gas-phase refrigerant from a gas-phase refrigerant inlet to a gas-phase refrigerant outlet. When,
With
The compression method is:
Inhaling the gas phase refrigerant into the speed compressor;
Accelerating and compressing the sucked gas phase refrigerant in the speed type compressor;
A flow path communicating with an outlet disposed on the surface of the rotating body, passing through the flow path located inside the rotating body, toward the gas-phase refrigerant existing in the refrigerant flow path. Injecting liquid phase refrigerant from the outlet;
Including a compression method.
The flow path located inside the rotating body extends in the axial direction of the rotating body inside the rotating body, and is located inside the rotating body, the main flow path through which the liquid-phase refrigerant flows, and the main stream Branching from the main path and extending from the main flow path to the refrigerant flow path, including an injection flow path for guiding the liquid refrigerant from the main flow path to the refrigerant flow path,
The compression method according to claim 16, wherein the liquid-phase refrigerant flowing through the main channel flows in a direction opposite to a direction in which the gas-phase refrigerant is sucked and flows.
The liquid phase refrigerant is ejected from the outlet by the centrifugal force generated by the rotation of the rotating body, and the ejected liquid phase refrigerant is sucked into the flow passage between the blades of the speed compressor.
The compression method according to claim 16 or 17.
The impeller has a hub and a blade fixed to the hub;
The outlet is positioned upstream of the upstream end of the blade in the flow direction of the gas-phase refrigerant.
The compression method according to any one of claims 16 to 18.