JP2020026919A - Refrigeration cycle system - Google Patents

Abstract

To provide a refrigeration cycle system that uses a low-cost configuration and can achieve good system efficiency by recovering expansion energy of a refrigerant in a refrigeration cycle.SOLUTION: A refrigeration cycle system comprises a two-phase flow turbine capable of being driven by expanding a refrigerant discharged from a first condenser of a first refrigeration cycle and a second condenser of a second refrigeration cycle, and a power generation device mechanically connected to the two-phase flow turbine. The refrigeration cycle system is constituted so that the refrigerant discharged from the two-phase flow turbine is supplied to both a first compressor and a second compressor via a first distribution flow passage.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a refrigeration cycle system capable of recovering expansion energy during an expansion stroke of a refrigeration cycle.

  A refrigeration cycle including a compression step, a condensation step, an expansion step, and an evaporation step is known. This type of refrigeration cycle is configured by arranging components such as a compressor, a condenser, an expansion valve, and an evaporator corresponding to each process on a circulation path through which a refrigerant flows, and is used for, for example, air conditioning. I have. When the refrigeration cycle functions as cooling, the high-temperature compressed refrigerant generated in the compression step is liquefied in the condensation step, decompressed in the expansion step, and then vaporized in the evaporation step to generate cold heat.

  In a typical refrigeration cycle, in the expansion step, a liquefied refrigerant is depressurized using a device such as an expansion valve. In Patent Document 1, instead of the expansion valve, a refrigerant in a gas-liquid mixed state is used. It is disclosed that by arranging a two-phase flow turbine that can be driven by (two-phase flow), the expansion energy generated in the expansion step is recovered to improve the system efficiency. Patent Literature 2 discloses an example of a two-phase flow turbine.

Japanese Utility Model Application Laid-Open No. 61-98954 U.S. Pat. No. 5,476,613

  Some systems using a refrigeration cycle include a plurality of refrigeration cycles. In this case, if the expansion process of each refrigeration cycle is to be realized by a two-phase flow turbine as in Patent Literature 1, two-phase flow turbines are required for the number of refrigeration cycles. Due to the high cost of two-phase flow turbines, such systems are disadvantageous in terms of profitability, and there are limits to improving system efficiency.

  At least one embodiment of the present invention has been made in view of the above circumstances, and a refrigeration cycle system capable of achieving good system efficiency by recovering the expansion energy of a refrigerant in a refrigeration cycle using a low-cost configuration. The purpose is to provide.

(1) A refrigeration cycle system according to at least one embodiment of the present invention,
A first compressor for compressing the refrigerant, a first condenser for condensing the refrigerant discharged from the first compressor, and a first evaporator for vaporizing the refrigerant discharged from the first condenser A first refrigeration cycle;
A second compressor that compresses the refrigerant, a second condenser that condenses the refrigerant discharged from the second compressor, and a second evaporator that vaporizes the refrigerant discharged from the second condenser. A second refrigeration cycle including:
A two-phase flow turbine drivable by expanding the refrigerant discharged from the first condenser and the second condenser;
A power generator mechanically connected to the two-phase flow turbine,
A first distribution channel configured to supply the refrigerant discharged from the two-phase flow turbine to the first compressor and the second compressor, respectively;
Is provided.

  According to the configuration of (1), at least a part of the expansion process in the plurality of refrigeration cycles forming the system is performed by the common two-phase flow turbine. Thereby, the expansion energy generated in the expansion stroke of each refrigeration cycle can be recovered by the two-phase flow turbine, and good system efficiency can be achieved. In addition, since the two-phase flow turbine is provided in common for a plurality of refrigeration cycles, good system efficiency can be obtained while suppressing costs, as compared with the case where a two-phase flow turbine is provided for each of the refrigeration cycles.

(2) In some embodiments, in the configuration of the above (1),
The first distribution channel includes:
A first expansion valve provided between the two-phase flow turbine and the first evaporator;
A second expansion valve provided between the two-phase flow turbine and the second evaporator;
Is provided.

  According to the above configuration (2), the first distribution flow path through which the refrigerant discharged from the two-phase flow turbine flows has the first expansion valve that forms the first refrigeration cycle and the first expansion valve that forms the second refrigeration cycle. Two expansion valves are provided. That is, the refrigerant discharged from the two-phase flow turbine is distributed to the first refrigeration cycle and the second refrigeration cycle via the first expansion valve and the second expansion valve provided in the first distribution channel. In such a configuration, since the two-phase flow turbine is provided upstream of the first expansion valve and the first expansion valve, the expansion energy can be recovered in a region where the heat drop is large, and good system efficiency can be achieved.

(3) In some embodiments, in the configuration of the above (2),
The first expansion valve and the second expansion valve can adjust a distribution ratio of the refrigerant from the two-phase flow turbine to the first refrigeration cycle and the second refrigeration cycle by adjusting respective opening degrees. Be composed.

  According to the configuration of (3), by adjusting the opening degrees of the first expansion valve and the second expansion valve provided on the downstream side of the two-phase flow turbine, respectively, the first refrigeration cycle and the second refrigeration cycle from the two-phase flow turbine The distribution ratio for two refrigeration cycles can be freely controlled. Thereby, the refrigerant after energy recovery in the two-phase flow turbine can be distributed at a flow rate suitable for the first refrigeration cycle and the second refrigeration cycle, so that better system efficiency can be achieved.

(4) In some embodiments, in any one of the above configurations (1) to (3),
A gas-liquid separator provided on the downstream side of the two-phase flow turbine,
A second distribution channel configured to supply a gas phase component of the refrigerant separated by the steam separator to the first compressor and the second compressor, respectively;
Is provided.

  According to the above configuration (4), the refrigerant after energy recovery discharged from the two-phase flow turbine can be separated into a gas phase component and a liquid phase component by the gas-liquid separator. The gas phase component separated by the gas-liquid separator is returned to the first compressor and the second compressor of each refrigeration cycle via the second distribution channel. This makes it possible to recompress and condense gas phase components that do not contribute to the heat of vaporization, thereby further improving system efficiency.

(5) In some embodiments, in any one of the above (1) to (4),
The two-phase flow turbine,
A first nozzle chamber including at least one first turbine nozzle configured to supply the refrigerant flowing from the first condenser to a turbine bucket;
A second nozzle chamber including at least one second turbine nozzle configured to supply the refrigerant flowing from the second condenser to the turbine bucket;
With
The first nozzle chamber and the second nozzle chamber are separated from each other.

  According to the configuration (5), the two-phase flow turbine is driven by the two-phase flow (mixed flow of the gas phase component and the liquid phase component) refrigerant introduced from the condenser of each refrigeration cycle. The two-phase flow turbine includes a first turbine nozzle that introduces a refrigerant flowing from a first condenser of a first refrigeration cycle and supplies the refrigerant to a turbine blade, and a refrigerant that flows from a second condenser of a second refrigeration cycle. A second turbine nozzle that is introduced and supplied to the turbine blade. The first turbine nozzle and the second turbine nozzle are disposed in a first nozzle chamber and a second nozzle chamber, respectively, and these are separated from each other. Thereby, even if there is a pressure difference between the refrigerant introduced from the first condenser and the second condenser to the two-phase flow turbine, energy loss can be suppressed and efficient power recovery can be performed. .

(6) In some embodiments, in the configuration of the above (5),
The first turbine nozzle and the second turbine nozzle are tapered-divergent nozzles.

  According to the above configuration (6), a tapered-divergent nozzle is adopted as the first turbine nozzle and the second turbine nozzle. As a result, droplets (liquid phase components) included in the two-phase flow passing through these turbine nozzles are effectively accelerated by the gas phase components, and the turbine blades can be driven more efficiently.

(7) In some embodiments, in the configuration of the above (6),
The first turbine nozzle and the second turbine nozzle are formed such that the area expansion ratio of the throat area to the outlet area decreases as the pressure ratio between the nozzle inlet pressure and the nozzle outlet pressure decreases.

  According to the configuration (7), the shape of the turbine nozzle used in the two-phase flow turbine is such that the smaller the pressure ratio between the nozzle inlet pressure and the nozzle outlet pressure, the smaller the area expansion ratio of the outlet area to the throat area. Designed. This makes it possible to optimize the expansion of the working fluid in the nozzle on the low pressure cycle side and accelerate the droplet acceleration in the nozzle, so that the turbine blade can be driven more efficiently.

(8) In some embodiments, in the configuration of (6) or (7),
The first turbine nozzle and the second turbine nozzle are formed such that the length from the throat portion to the nozzle outlet increases as the nozzle inlet pressure decreases.

  According to the above configuration (8), the length of the turbine nozzle used in the two-phase flow turbine is designed according to the nozzle inlet pressure of the turbine nozzle. For example, when the inlet pressure of the turbine nozzle is small, the flow velocity of the droplet (liquid phase component) included in the two-phase flow is relatively slow. The flow rate at the outlet can be increased. Thereby, the turbine bucket can be driven more efficiently.

(9) In some embodiments, in any one of the above configurations (5) to (8),
A first flow control valve for controlling a flow rate of the refrigerant with respect to the first nozzle chamber;
A second flow control valve for controlling the flow rate of the refrigerant with respect to the second nozzle chamber,
With
In the first flow control valve and the second flow control valve, a ratio U / C0 of a rotational speed U of the two-phase flow turbine to a theoretical speed C0 of a nozzle inlet pressure and a turbine outlet pressure is within a predetermined range. Is controlled as follows.

  According to the configuration of (9), the flow rate of the refrigerant to the first nozzle chamber and the second nozzle chamber is determined by the first flow control valve and the second flow control valve so that the ratio U / C0 having a correlation with the system efficiency is predetermined. It is controlled to be within the range. Thereby, for example, even when the operation state of the present system changes like partial load operation, predetermined system efficiency is ensured. That is, a system performance that is robust against partial loads is obtained.

(10) In some embodiments, in the configuration of the above (9),
The first flow control valve is provided in the first nozzle chamber including a plurality of the first turbine nozzles,
The second flow control valve is provided in the second nozzle chamber including a plurality of the second turbine nozzles.

  According to the above configuration (10), since the first flow control valve and the second flow control valve are provided for the first nozzle chamber and the second nozzle chamber, respectively, the refrigerant in the turbine nozzle provided in each nozzle chamber is provided. Can be adjusted collectively.

(11) In some embodiments, in the configuration of the above (9),
The first flow control valve is provided in each of the plurality of first turbine nozzles,
The second flow control valve is provided in each of the plurality of second turbine nozzles.

  According to the above configuration (11), the first flow rate control valve and the second flow rate control valve are provided for each turbine nozzle included in the first nozzle chamber and the second nozzle chamber, respectively. The flow rate of the refrigerant can be finely adjusted.

(12) In some embodiments, in the configuration of the above (11),
The first turbine nozzle and the second turbine nozzle are reamer nozzles.

  According to the configuration (12), since the first turbine nozzle and the second turbine nozzle are configured as reamer nozzles, the flow control valve can be easily provided for each turbine nozzle.

According to at least one embodiment of the present invention, it is possible to provide a refrigeration cycle system that can achieve good system efficiency by recovering expansion energy of a refrigerant in a refrigeration cycle using a low-cost configuration.

It is a lineblock diagram showing the whole refrigeration cycle system composition concerning at least one embodiment of the present invention. FIG. 2 is an axial cross-sectional view of the two-phase flow turbine of FIG. 1. FIG. 3 is a schematic diagram illustrating a first nozzle chamber and a second nozzle chamber in an axial vertical plane of FIG. 2. FIG. 4 is a schematic view illustrating an example of a first turbine nozzle and a second turbine nozzle provided in a first nozzle chamber and a second nozzle chamber of FIG. 3. It is a schematic diagram which shows the flow of the two-phase flow refrigerant in a taper-divergent nozzle. It is a modification of FIG. It is a first modified example of FIG. 5 is a graph showing a correlation between a power generation efficiency of a generator and a parameter ratio of a two-phase flow turbine. It is a 2nd modification of FIG. 1 is a configuration diagram illustrating an entire configuration of a refrigeration cycle system according to a base technology.

  Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.

<Prerequisite technology>
First, a base technology of a refrigeration cycle system according to at least one embodiment of the present invention will be described. FIG. 10 is a configuration diagram showing an overall configuration of a refrigeration cycle system 10 'according to the base technology. The refrigeration cycle system 10 'is an air conditioning system using a refrigeration cycle. In the following description, a state in which the refrigeration cycle system 10 'is operated in a cooling cycle will be described, but the present invention is also applicable to a state in which it is operated in a heating cycle unless otherwise specified.

  Refrigeration cycle system 10 'typically includes two systems of refrigeration cycles (first refrigeration cycle 10A and second refrigeration cycle 10B) including a compression step, a condensation step, an expansion step, and an evaporation step. Each of the first refrigeration cycle 10A and the second refrigeration cycle 10B is configured by arranging a compressor, a condenser, an expansion valve, and an evaporator corresponding to each process on a circulation path through which a refrigerant flows, and is independent of each other. are doing.

  The first refrigeration cycle 10A includes a first compressor 14A, a first condenser 16A, a first upstream expansion valve 18A, a first gas-liquid separator 20A, a first downstream expansion valve 22A, One evaporator 24A is arranged in order. The first compressor 14A is a multi-stage type and includes a first low-pressure compressor 14A1 and a first high-pressure compressor 14A2 arranged in series along the circulation path 12A. The first low-pressure side compressor 14A1 and the first high-pressure side compressor 14A2 are coaxially connected to each other, and are configured to be drivable by the electric motor 26A.

  The high-temperature and high-pressure refrigerant discharged from the first compressor 14A is sent to the first condenser 16A and is condensed by heat exchange with the outside air. The refrigerant condensed in the first condenser 16A is decompressed by the first upstream expansion valve 18A, and then gas-liquid separated by the first gas-liquid separator 20A. A part of the gas phase component separated by the first gas-liquid separator 20A is recompressed by returning to the first high-pressure side compressor 14A2 via the return line 28A, and the rest is mixed with the first component together with the liquid phase component. The pressure is further reduced by the downstream expansion valve 22A.

  The refrigerant discharged from the first downstream expansion valve 22A is supplied to the first evaporator 24A. The first evaporator 24A cools the cooling water by exchanging heat between the refrigerant and the cooling water to generate cold heat due to the heat of vaporization of the refrigerant. The refrigerant that has completed the heat exchange in the first evaporator 24A is returned to the first compressor 14A, and the above cycle is repeated.

  The second refrigeration cycle 10B includes a second compressor 14B, a second condenser 16B, a second upstream expansion valve 18B, a second gas-liquid separator 20B, a second downstream expansion valve 22B, Two evaporators 24B are arranged in order. The second compressor 14B is a multi-stage type and includes a second low-pressure side compressor 14B1 and a second high-pressure side compressor 14B2 arranged in series along the circulation path 12B. The second low-pressure side compressor 14B1 and the second high-pressure side compressor 14B2 are coaxially connected to each other, and are configured to be drivable by the electric motor 26B.

  The high-temperature and high-pressure refrigerant discharged from the second compressor 14B is sent to the second condenser 16B and is condensed by heat exchange with the outside air. The refrigerant condensed in the second condenser 16B is decompressed by the second upstream expansion valve 18B, and then gas-liquid separated by the second gas-liquid separator 20B. Part of the gas phase component separated by the second gas-liquid separator 20B is recompressed by being returned to the second high-pressure side compressor 14B2 via the return line 28B, and the rest is mixed with the second component together with the liquid phase component. The pressure is further reduced by the downstream expansion valve 22B.

  The refrigerant discharged from the second downstream expansion valve 22B is supplied to the second evaporator 24B. The second evaporator 24B exchanges heat between the refrigerant and the cooling water to generate cold heat due to the heat of vaporization of the refrigerant, thereby cooling the cooling water. The refrigerant that has completed the heat exchange in the second evaporator 24B is returned to the second compressor 14B, and the above cycle is repeated.

  In addition, these two refrigeration cycles (the first refrigeration cycle 10A and the second refrigeration cycle 10B) change the state at each point of the circulation paths 12A and 12B in accordance with the amount of cold supplied to the cooling water to be exchanged. The amount (pressure, temperature, etc.) is set. In FIG. 10, the first evaporator 24A and the second evaporator 24B are arranged in series with respect to the flow direction of the cooling water. In particular, the first evaporator 24A is arranged downstream of the second evaporator 24B. Have been.

  Note that the refrigerants handled in the first refrigeration cycle 10A and the second refrigeration cycle 10B are the same, and for example, R134a, R1233ZDE, R1234ZE, or the like is used.

  Here, in the above-described refrigeration cycle system 10 ', it is conceivable to introduce a two-phase flow turbine for each of the expansion steps of the first refrigeration cycle 10A and the second refrigeration cycle 10B in order to improve system efficiency. In this case, two-phase flow turbines are required for the number of refrigeration cycles included in the refrigeration cycle system 10 '(that is, "2"). Due to the high cost of two-phase flow turbines, such systems are disadvantageous in terms of profitability, and there are limits to improving system efficiency. Such a problem can be solved by the embodiments described below.

<Refrigeration cycle system>
FIG. 1 is a configuration diagram showing an overall configuration of a refrigeration cycle system 10 according to at least one embodiment of the present invention. In the following description, components corresponding to the above-described prerequisite technology are denoted by common reference numerals, and repeated description will be omitted unless otherwise specified.

  The first refrigeration cycle 10A and the second refrigeration cycle 12 included in the refrigeration cycle system 10 have the same configuration regarding the compression step, the condensation step, and the evaporation step as the above-described base technology, but differ in the configuration regarding the expansion step. That is, it is possible to improve the following embodiment by changing the configuration related to the expansion process in the base technology.

  The refrigeration cycle system 10 is a two-phase drivable by expanding the refrigerant discharged from the first condenser 16A constituting the first refrigeration cycle 10A and the second condenser 16B constituting the second refrigeration cycle 10B. A flow turbine 30 is provided. The two-phase flow turbine 30 uses a turbine blade 52 (see FIG. 2) by expansion energy generated when the two-phase flow refrigerant condensed in the first condenser 16A and the second condenser 16B is depressurized. ) Is driven. The turbine blade 52 generates electric energy by driving a generator 34 mechanically connected to the rotating shaft 32 via the rotating shaft 32. As described above, the two-phase flow turbine 30 recovers expansion energy generated in the expansion step as electric energy.

  The electric energy generated by the generator 34 may be stored in a power storage device such as a battery (not shown), or may be directly supplied to a load that consumes the electric energy.

  As described above, in the refrigeration cycle system 10, at least a part of the expansion process in the first refrigeration cycle 10A and the second refrigeration cycle 10B is performed by the common two-phase flow turbine 30. Thereby, the expansion energy generated during the expansion process in each of the first refrigeration cycle 10A and the second refrigeration cycle 10B can be recovered by the single two-phase flow turbine 30, and good system efficiency can be achieved. Since the two-phase flow turbine 30 is provided commonly to the first refrigeration cycle 10A and the second refrigeration cycle 10B, the two-phase flow turbine is provided for each of the first refrigeration cycle 10A and the second refrigeration cycle 10B. As compared with the above, good system efficiency can be obtained while suppressing costs.

  A gas-liquid separator 36 is provided downstream of the two-phase flow turbine 30. In the base technology, the first gas-liquid separator 20A and the second gas-liquid separator 20B are provided for the first refrigeration cycle 10A and the second refrigeration cycle 10B, but in the present embodiment, a common two-phase flow is used. By providing the gas-liquid separator 36 on the downstream side of the turbine 30, the system configuration can be prevented from becoming complicated and large.

  The refrigerant discharged from the gas-liquid separator 36 passes through the first distribution channels 38A and 38B to the first evaporator 24A of the first refrigeration cycle 10A and the second evaporator 24B of the second refrigeration cycle 10B. Supplied respectively. Thereby, the refrigerant that has passed through the two-phase flow turbine 30 and the gas-liquid separator 36 common to the two refrigeration cycles is distributed to the two refrigeration cycles 10A and 10B via the first distribution channels 38A and 38B.

  In the first distribution flow paths 38A and 38B, a first expansion valve 40A provided between the two-phase flow turbine 30 and the first evaporator 24A, and between the two-phase flow turbine and the second evaporator 24B. And the second expansion valve 40B provided. That is, the refrigerant discharged from the two-phase flow turbine 30 is further depressurized by the first expansion valve 40A and the second expansion valve 40B provided in the first distribution flow paths 38A and 38B, and then the first evaporator 24A and It is distributed to the second evaporator 24B. In other words, in the present embodiment, the first upstream expansion valve 18A and the second upstream expansion valve 18B are replaced with the two-phase flow turbine 30 in the above-described base technology (see FIG. 10), and the first downstream expansion valve 22A is used. The second downstream expansion valve 22B is left as a first expansion valve 40A and a second expansion valve 40B. In such a configuration, since the two-phase flow turbine 30 is provided upstream of the first expansion valve 40A and the second expansion valve 40B, the expansion energy can be recovered in a region where the heat drop is large, and good system efficiency is achieved. it can.

  The distribution flow rate of the refrigerant to the first refrigeration cycle 10A and the second refrigeration cycle 10B by the first distribution channels 38A and 38B is, for example, the first expansion valve 40A and the second expansion valve provided on the first distribution channel 38. It may be implemented by adjusting the opening degree of each of the 40Bs. Thereby, the refrigerant whose energy has been recovered by the two-phase flow turbine 30 can be distributed at a flow rate suitable for the first refrigeration cycle 10A and the second refrigeration cycle 10B, so that better system efficiency can be achieved. In particular, even in the case where the prerequisite technology is modified to introduce the two-phase flow turbine 30, the opening of each of the first expansion valve 40A and the second expansion valve 40B is appropriately adjusted, so that each cycle can be started. Can be easily optimized. As a result, it is possible to easily perform a modification for introducing the two-phase flow turbine 30 to an existing system corresponding to the base technology.

  The refrigeration cycle system 10 also includes second distribution channels 42A and 42B configured to supply the gas phase component of the refrigerant separated by the gas-liquid separator 36 to the first compressor 14A and the second compressor 14B, respectively. Is provided. The refrigerant discharged from the two-phase flow turbine 30 after energy recovery contains a gas phase component and a liquid phase component, and these are separated by the gas-liquid separator 36. The gas phase component separated by the gas-liquid separator 36 is returned to the first compressor 14A and the second compressor 14B of each refrigeration cycle via the second distribution channels 42A and 42B. This makes it possible to recompress and condense gaseous phase components that do not contribute to the heat of vaporization in the first evaporator 24A and the second evaporator 24B, thereby further improving system efficiency.

<Two-phase flow turbine>
Next, a specific configuration of the two-phase flow turbine 30 used in the refrigeration cycle system 10 will be described. FIG. 2 is an axial cross-sectional view of the two-phase flow turbine 30 of FIG. 1, and FIG. 3 is a schematic diagram showing the first nozzle chamber 54A and the second nozzle chamber 54B in the axial vertical plane of FIG.
In the following, when simply described as “circumferential direction”, “axial direction”, and “radial direction”, it means the circumferential direction, axial direction, and radial direction of the two-phase flow turbine 30, respectively.

  The two-phase flow turbine 30 is provided on a rotating shaft 50 extending along the axial direction, a plurality of turbine moving blades 52 arranged on the rotating shaft 50 along the circumferential direction, and an upstream side of the turbine moving blade 52. The first nozzle chamber 54 </ b> A and the second nozzle chamber 54 </ b> B, and a turbine diffuser 56 provided downstream of the turbine blade 52.

  As described above, the refrigerant condensed from the first refrigeration cycle 10A (first condenser) and the second refrigeration cycle 10B (second condenser) is introduced into the two-phase flow turbine 30 as described above. The refrigerant introduced from the first refrigerant cycle 10A (the first condenser 16A) is supplied to the turbine blade 52 via the first nozzle chamber 54A. The refrigerant introduced from the second refrigerant cycle 10B (second condenser 16B) is supplied to the turbine blade 52 via the second nozzle chamber 54B.

  As shown in FIG. 3, the first nozzle chamber 54A and the second nozzle chamber 54B are arranged at different positions along the circumferential direction around the rotation shaft 50 and are separated from each other. Thereby, even when there is a pressure difference between the refrigerant introduced from the first condenser 16A and the second condenser 16B to the two-phase flow turbine 30, the energy loss is suppressed to be small, and efficient power recovery is performed. be able to.

  The first nozzle chamber 54A includes at least one first turbine nozzle 58A configured to supply the refrigerant flowing from the first condenser 16A to the turbine bucket 52. The second nozzle chamber 54B includes at least one second turbine nozzle 58B configured to supply the refrigerant flowing from the second condenser 16B to the turbine bucket 52.

  Here, FIG. 4 is a schematic diagram showing an example of the first turbine nozzle 58A and the second turbine nozzle 58B provided in the first nozzle chamber 54A and the second nozzle chamber 54B of FIG. In this embodiment, a case where a plurality of first turbine nozzles 58A and a plurality of second turbine nozzles 58B are provided in the first nozzle chamber 54A and the second nozzle chamber 54B respectively will be described. The number of nozzles 58B may be the same or different.

  The first turbine nozzle 58A and the second turbine nozzle 58B are tapered-divergent nozzles. Such a tapered-divergent nozzle is, for example, a reamer nozzle formed by reamer processing. FIG. 5 is a schematic diagram showing the flow of the two-phase refrigerant in the convergent-divergent nozzle. As shown in FIG. 5, the tapered-divergent nozzle gradually decreases in inner diameter from the nozzle inlet portion 60a having the inner diameter D1 toward the throat portion 60b, has the minimum diameter D2 in the throat portion 60b, and has the throat portion 60b. Is configured so that the inner diameter gradually increases from the nozzle toward the nozzle outlet portion 60c having the inner diameter D3 (that is, D1> D2 and D2 <D3).

  The liquid refrigerant condensed from the first condenser 16A or the second condenser 16B is supplied to the nozzle inlet 60a. The refrigerant introduced into the nozzle inlet portion 60a is compressed toward the throat portion 60b, and is flushed in the throat portion 60b, so that the refrigerant becomes a two-phase flow of a gas phase and a liquid phase. The two-phase flow includes droplets 64 in gas 62. Since the weight of the droplet 64 is larger than that of the gas 62, the flow rate of the liquid 64 is smaller than the flow rate of the gas 62 (for example, the flow rate of the gas 62 is about 10 times the flow rate of the liquid 64). The liquid 64 is accelerated from the throat portion 60b to the nozzle outlet portion 60c by the high-speed gas 62 existing around. At the nozzle outlet 60c, a two-phase flow including the accelerated droplets 64 is discharged toward the turbine blade. The two-phase flow discharged from the nozzle outlet 60c drives the turbine blade, and at this time, the accelerated droplet 64 mainly contained in the two-phase flow gives kinetic energy to the turbine blade. Become.

  In the present embodiment, as described above, the first nozzle chamber 54A and the second nozzle chamber 54B are supplied with refrigerants having different pressures from the first refrigeration cycle 10A and the second refrigeration cycle 10B. A refrigerant having a higher pressure than the second nozzle chamber 54B is supplied to 54A. The first turbine nozzle 58A and the second turbine nozzle 58B have different nozzle shapes according to the pressure. Specifically, as the pressure ratio P3 / P1 of the pressure P1 at the nozzle inlet 60a and the pressure P3 at the nozzle outlet 60c decreases, the first turbine nozzle 58A and the second turbine nozzle 58B flow through the throat portion 60b. The area expansion ratio ρ3 / ρ2 of the flow path area ρ3 of the nozzle outlet 60c with respect to the area ρ2 is formed to be smaller. Thereby, the expansion of the working fluid in the nozzle on the low pressure cycle side in the nozzle can be optimized, and the acceleration of the droplet in the nozzle can be promoted, so that the turbine bucket 52 can be driven more efficiently.

  The first turbine nozzle 58A and the second turbine nozzle 58B may be formed such that the length L from the throat portion 60b to the nozzle outlet 60c increases as the pressure P1 at the nozzle inlet 60a decreases.

  As described above with reference to FIG. 5, in the tapered-divergent nozzle, the droplet 64 generated at the throat portion 60b is a high-speed gas in the range of the length L between the throat portion 60b and the nozzle outlet portion 60c. Accelerated by 62. Therefore, when the inlet pressure of the turbine nozzle is small, the flow velocity of the liquid droplet (liquid phase component) included in the two-phase flow is relatively low, so that a large acceleration section is secured by designing the nozzle length to be large, The flow velocity at the nozzle outlet 60c can be increased.

  FIG. 6 is a modification of FIG. 4, but since the first turbine nozzle 58A is supplied with a refrigerant having a higher pressure than the second turbine nozzle 58B, in this modification, the length L2 of the second turbine nozzle 58B is , The first turbine nozzle 58A is set to be longer than the length L1. Thereby, the turbine bucket 52 can be driven more efficiently.

<First Modification>
FIG. 7 shows a first modification of FIG. In the present modified example, a first flow rate control valve 60A and a second flow rate control valve 60B are provided at the nozzle inlet portion 60a of the first nozzle chamber 54A and the second nozzle chamber 54B, respectively. The first flow control valve 60A and the second flow control valve 60B are configured to control the flow rate of the refrigerant to the first nozzle chamber 54A and the second nozzle chamber 54B by adjusting the opening.
The control of the first flow control valve 60A and the second flow control valve 60B may be performed manually (manually) by an operator, or automatically performed using an electronic arithmetic device such as a computer. Is also good.

  Here, FIG. 8 is a graph showing a correlation of the power generation efficiency η of the generator with respect to the parameter ratio U / C0 of the two-phase flow turbine 30. Here, U is the rotational peripheral speed (m / s) of the two-phase flow turbine 30, C0 indicates the theoretical speed at the turbine inlet (nozzle inlet) and the turbine outlet (moving blade outlet), and C0 indicates the turbine pressure ratio. Correlate. The turbine pressure ratio is defined by the pressure ratio at the turbine outlet to the turbine inlet. In the present embodiment, the pressure P1 (see FIG. 5) at the nozzle inlet 60a of the first nozzle chamber 54A or the second nozzle chamber 54B corresponds to the pressure at the turbine inlet. Although the pressure at the turbine outlet is strictly the outlet pressure of the turbine blade 52, in the present embodiment, it is simply assumed to be equivalent to the pressure P3 (see FIG. 5) at the nozzle outlet 60c. Therefore, the turbine pressure ratio is defined by the ratio P1 / P3 of the nozzle inlet pressure P1 to the nozzle outlet pressure P3. As shown in FIG. 8, the efficiency η has a maximum value at a specific parameter ratio U / C0, and the efficiency η tends to decrease when the operating state of the two-phase flow turbine 30 deviates from the optimum value. .

  In the present modification, the opening degree of the first flow control valve 60A and the second flow control valve 60B is controlled such that the parameter ratio U / C0 falls within a predetermined range including the maximum value of the efficiency η. In the example of FIG. 8, the control range R of the parameter ratio U / C0 is indicated by hatching. As a result, for example, even when the operation state of the refrigeration cycle system 10 changes like partial load operation, a predetermined system efficiency is ensured. That is, a system performance that is robust against partial loads is obtained.

<Modification 2>
FIG. 9 shows a second modification of FIG. In the first modified example (FIG. 7), the first flow control valve 60A and the second flow control valve 60B are provided for the first nozzle chamber 54A and the second nozzle chamber 54B, but in the second modified example. 9, may be provided for each of the first turbine nozzle 58A and the second turbine nozzle 58B. That is, the first flow rate control valve 60A and the second flow rate control valve 60B are individually provided for the first turbine nozzle 58A and the second turbine nozzle 58B included in the first nozzle chamber 54A and the second nozzle chamber 54B. Is also good.

  In the second modified example, as in the first modified example described above, the first flow rate control valve 60A and the second flow rate control valve 60B are such that the parameter ratio U / C0 falls within a predetermined range including the maximum value of the efficiency η. The degree of opening is controlled. In the second modified example, the first flow rate control valve 60A and the second flow rate control valve 60B are separately provided for the first turbine nozzle 58A and the second turbine nozzle 58B, so that the flow rate of the refrigerant for each turbine nozzle Can be finely adjusted. Therefore, compared to the first modification, the opening degree can be controlled with higher accuracy so that the parameter ratio U / C0 falls within a predetermined range including the maximum value of the efficiency η.

  In the second modified example, it is necessary to connect the first flow control valve 60A and the second flow control valve 60B to the first turbine nozzle 58A and the second turbine nozzle 58B. The second turbine nozzle 58B is easily realized by, for example, using a reamer nozzle that is easily mechanically connected. Obviously, the first turbine nozzle 58A and the second turbine nozzle 58B can take other forms of the reamer nozzle.

  As described above, according to at least one embodiment of the present invention, it is possible to provide a refrigeration cycle system capable of achieving good system efficiency by recovering refrigerant expansion energy in a refrigeration cycle using a low-cost configuration.

  At least one embodiment of the present invention is applicable to a refrigeration cycle system capable of recovering expansion energy in an expansion stroke of a refrigeration cycle.

10 Refrigeration cycle system 10A First refrigeration cycle 10B Second refrigeration cycle 12A, 12B Circulation path 14A First compressor 14B Second compressor 16A First condenser 16B Second condenser 24A First evaporator 24B Second evaporator 26A , 26B Electric motor 30 Two-phase flow turbine 34 Generator 36 Gas-liquid separator 38A, 38B First distribution channel 40A First expansion valve 40B Second expansion valve 42A, 42B Second distribution channel 52 Turbine blade 54A First nozzle Chamber 54B Second nozzle chamber 58A First turbine nozzle 58B Second turbine nozzle 60A First flow control valve 60B Second flow control valve 60a Nozzle inlet 60b Throat 60c Nozzle outlet

Claims (12)

A first compressor for compressing the refrigerant, a first condenser for condensing the refrigerant discharged from the first compressor, and a first evaporator for vaporizing the refrigerant discharged from the first condenser A first refrigeration cycle;
A second compressor that compresses the refrigerant, a second condenser that condenses the refrigerant discharged from the second compressor, and a second evaporator that vaporizes the refrigerant discharged from the second condenser. A second refrigeration cycle including:
A two-phase flow turbine drivable by expanding the refrigerant discharged from the first condenser and the second condenser;
A power generator mechanically connected to the two-phase flow turbine,
A first distribution channel configured to supply the refrigerant discharged from the two-phase flow turbine to the first compressor and the second compressor, respectively;
A refrigeration cycle system comprising: The first distribution channel includes:
A first expansion valve provided between the two-phase flow turbine and the first evaporator;
A second expansion valve provided between the two-phase flow turbine and the second evaporator;
The refrigeration cycle system according to claim 1, comprising:   The first expansion valve and the second expansion valve can adjust a distribution ratio of the refrigerant from the two-phase flow turbine to the first refrigeration cycle and the second refrigeration cycle by adjusting respective opening degrees. The refrigeration cycle system according to claim 2, wherein the refrigeration cycle system is configured. A gas-liquid separator provided on the downstream side of the two-phase flow turbine,
A second distribution channel configured to supply a gas phase component of the refrigerant separated by the steam separator to the first compressor and the second compressor, respectively;
The refrigeration cycle system according to any one of claims 1 to 3, further comprising: The two-phase flow turbine,
A first nozzle chamber including at least one first turbine nozzle configured to supply the refrigerant flowing from the first condenser to a turbine bucket;
A second nozzle chamber including at least one second turbine nozzle configured to supply the refrigerant flowing from the second condenser to the turbine bucket;
With
The refrigeration cycle system according to any one of claims 1 to 4, wherein the first nozzle chamber and the second nozzle chamber are separated from each other.   The refrigeration cycle system according to claim 5, wherein the first turbine nozzle and the second turbine nozzle are tapered-divergent nozzles.   The said 1st turbine nozzle and the said 2nd turbine nozzle are formed so that the area expansion ratio of an outlet area with respect to a throat area may become small, so that the pressure ratio of a nozzle inlet pressure and a nozzle outlet pressure becomes small. A refrigeration cycle system as described.   8. The refrigeration cycle according to claim 6, wherein the first turbine nozzle and the second turbine nozzle are formed such that the length from the throat portion to the nozzle outlet increases as the nozzle inlet pressure decreases. 9. system. A first flow control valve for controlling a flow rate of the refrigerant with respect to the first nozzle chamber;
A second flow control valve for controlling the flow rate of the refrigerant with respect to the second nozzle chamber,
With
In the first flow control valve and the second flow control valve, a ratio U / C0 of a rotational speed U of the two-phase flow turbine to a theoretical speed C0 of a nozzle inlet pressure and a turbine outlet pressure is within a predetermined range. The refrigeration cycle system according to any one of claims 5 to 8, which is controlled as follows. The first flow control valve is provided in the first nozzle chamber including a plurality of the first turbine nozzles,
The refrigeration cycle system according to claim 9, wherein the second flow control valve is provided in the second nozzle chamber including a plurality of the second turbine nozzles. The first flow control valve is provided in each of the plurality of first turbine nozzles,
The refrigeration cycle system according to claim 9, wherein the second flow control valve is provided in each of the plurality of second turbine nozzles.   The refrigeration cycle system according to claim 11, wherein the first turbine nozzle and the second turbine nozzle are reamer nozzles.

Images