JP2009270745A - Refrigerating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a coefficient of performance (COP) and therefore a refrigerating capacity in the refrigerating cycle using carbon dioxide as a refrigerant and using an expanding machine and an aspirator. <P>SOLUTION: A first gas-liquid separator 15 is disposed between the expanding machine 14 and the aspirator 20, a gas outlet side of the first gas separator and a suction side of a second compressor 12 are connected by piping, a liquid outlet side of the first gas-liquid separator is connected with the aspirator by piping, a second gas-liquid separator 16 is disposed between the aspirator and a first compressor 10, a gas outlet side of the second gas-liquid separator and a suction side of the first compressor are connected by piping, on the other hand, a liquid outlet side of the second gas-liquid separator is connected to an evaporator 18 by piping through a throttle device 17, an outlet of the evaporator is connected to a suction port 22 of the aspirator by piping, and internal heat exchangers 30 exchanging heat to each other, are disposed in the piping between a liquid outlet side of the first gas-liquid separator 15 and the aspirator 20, and the piping between an outlet of the evaporator 18 and the suction port 22 of the aspirator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle that uses carbon dioxide as a refrigerant, recovers power from the expansion energy of an expander, and realizes high efficiency by utilizing the pressure reduction effect of an aspirator.

Conventionally, in a vehicle air conditioner, carbon dioxide (CO ₂ ) is used as a refrigerant, and a refrigeration cycle using an aspirator and a refrigeration cycle that collects expansion energy in an expansion stroke as power are known.
The refrigeration cycle using this aspirator is composed of a compressor, a gas cooler, an aspirator, and a gas-liquid separator. The gas refrigerant separated by the gas-liquid separator is sucked into the compressor, and the liquid refrigerant is evaporated. After being guided to evaporate, it is again sucked into the aspirator. By doing so, the enthalpy at the outlet of the aspirator is reduced by adiabatic expansion in the aspirator, the cooling capacity in the evaporator is increased, and the coefficient of performance (COP) of the refrigeration cycle is improved.

In addition, the refrigerant gas exiting the evaporator is pressurized by an aspirator, and then flows into the gas-liquid separator and only the gas refrigerant is sucked into the compressor. The coefficient is improved.
Further, in a power recovery system using an expander that has attracted attention in recent refrigeration cycle apparatuses using carbon dioxide refrigerant, an expander is provided at the radiator outlet in order to further improve the refrigeration cycle efficiency of the carbon dioxide refrigerant. As a result, it is possible to improve the coefficient of performance by recovering energy lost by expansion of the refrigerant from high pressure to low pressure. Further, since the expansion by the expander can be brought close to adiabatic expansion, the enthalpy at the evaporator inlet is reduced, the amount of heat absorbed in the evaporator is increased, and the refrigerating capacity can be improved.

For example, by connecting a compressor, a radiator, an expander, an expansion valve, and an evaporator in order, the refrigerant at the outlet of the radiator is decompressed and expanded by the expander. It can be used, and it is possible to reduce the required power and improve the refrigerating capacity.
In addition, since the outlet pressure of the expander is set higher than the critical pressure of carbon dioxide by the expansion valve, carbon dioxide can be maintained in a supercritical state even after being expanded by the expander. It is possible to prevent the gas-liquid two-phase state from being caused by the decompression and expansion, and the liquid refrigerant can be prevented from causing noise and failure of the expander. In this way, by utilizing the properties of carbon dioxide refrigerant in which the high-pressure side line is in the supercritical region, pressure energy is safely recovered and effectively used, thereby simultaneously reducing the required power and increasing the refrigeration effect. High efficiency of the cycle device can be realized.

Further, in the refrigeration system, the compressor is divided into a first compressor and a second compressor, the first compressor and the second compressor are provided in series, and the second compressor is connected to the first compressor from the outlet of the first compressor. A gas injection cycle having a refrigeration cycle capable of keeping the refrigerant temperature of the second compressor low by flowing a low-temperature refrigerant from the expander outlet in addition to the refrigerant of the above has been developed (Patent Document) 1 and 2).
JP 2003-65615 A JP 2004-251558 A

  By the way, in the above refrigeration system, the aspirator has a function of reducing the work of the compressor by once reducing the pressure of the refrigerant and then increasing the suction pressure of the compressor by the pressure increasing action of the diffuser at the outlet of the aspirator and decreasing the compression ratio. Therefore, in order to make the pressure reducing action and the pressure raising action effective, it is desirable that the refrigerant sucked into the aspirator again through the evaporator is a gas refrigerant in a sufficiently gasified state. .

However, in the conventional configuration, the evaporator may not be able to gasify the liquid refrigerant sufficiently depending on the situation. In this case, the gas-liquid two-phase refrigerant is sucked into the aspirator. This is not preferable because the work of the compressor cannot be sufficiently reduced.
In addition, when the suction pressure of the compressor is increased in this way, the discharge gas temperature tends to increase due to the large specific heat ratio as a characteristic of carbon dioxide, particularly in a refrigeration cycle using a carbon dioxide refrigerant. When carbon refrigerant is used in a low-temperature refrigerator, there is also a problem that the discharge gas temperature rises remarkably because the evaporation temperature is low, the reliability of the equipment is lowered, and the coefficient of performance tends to be lowered.

  The present invention has been made in view of such problems, and in a refrigeration cycle using carbon dioxide as a refrigerant and using an expander and an aspirator, a refrigeration system that improves the coefficient of performance (COP) and thus the refrigeration capacity is provided. The purpose is to provide.

  In order to achieve the above object, a refrigeration system according to claim 1 includes a first compressor that compresses the refrigerant using carbon dioxide as a refrigerant, and a second compressor that is connected in series to the first compressor, A gas cooler that cools the refrigerant whose pressure has been increased by the second compressor, an expander that decompresses and expands the cooled refrigerant, and an aspirator are sequentially connected by pipes, and a second is connected between the expander and the aspirator. One gas-liquid separator is provided, and the gas outlet side of the first gas-liquid separator and the suction side of the second compressor are connected by piping, while the liquid outlet side of the first gas-liquid separator is connected to the aspirator. A pipe is connected, a second gas-liquid separator is provided between the aspirator and the first compressor, and the gas outlet side of the second gas-liquid separator and the suction side of the first compressor are connected by pipe. On the other hand, the liquid outlet side of the second gas-liquid separator is connected to the evaporator and the pipe through a throttling device. In addition, the outlet of the evaporator is connected to the suction port of the aspirator by piping, the pipe between the liquid outlet side of the first gas-liquid separator and the aspirator, the outlet of the evaporator and the aspirator An internal heat exchanger capable of exchanging heat with each other is provided in a pipe between the suction port and the pipe.

The refrigeration system according to claim 2 is the refrigeration system according to claim 1, further comprising a pipe between the gas cooler and the expander, a gas outlet side of the first gas-liquid separator, and an intake of the second compressor. A second internal heat exchanger capable of exchanging heat with each other is provided in a pipe between the two sides.
The refrigeration system according to claim 3 is characterized in that, in claim 1 or 2, the power recovered by the expander is used for driving at least one of the first compressor and the second compressor. .

A refrigeration system according to claim 4 is characterized in that, in claim 1 or 2, a generator is connected to the expander.
The refrigeration system according to claim 5 is characterized in that, in claim 1 or 2, an electric motor connected to at least one of the first compressor and the second compressor is connected to the expander. .

Further, in the refrigeration system according to claim 6, in claim 1 or 2, a rotating machine connected to at least one of the first compressor and the second compressor is connected to the expander, and mutual needs are made. The rotating machine is operated as an electric motor or a generator according to power.
Further, in the refrigeration system according to claim 7, in any one of claims 1 to 6, the first compressor and the second compressor are scroll type, turbine type, rotary type, swing type, swash plate type, screw type, The expander is any of a vane type, a scroll type, a turbine type, a rotary type, and a vane type.

  In the refrigeration system according to claim 8, a scroll compressor that compresses the refrigerant using carbon dioxide as a refrigerant, a gas cooler that cools the refrigerant pressurized by the scroll compressor, and the cooled refrigerant And an aspirator are sequentially connected by piping, and a first gas-liquid separator is provided between the expander and the aspirator. A gas outlet side of the first gas-liquid separator and the scroll type are provided. While connecting the intermediate pressure region of the compressor with a pipe, the liquid outlet side of the first gas-liquid separator is connected with the aspirator, and a second gas-liquid separator is provided between the aspirator and the scroll compressor. And connecting the gas outlet side of the second gas-liquid separator and the suction side of the scroll compressor by piping, and connecting the liquid outlet side of the second gas-liquid separator via an expansion device to the evaporator Connect the piping and the steam The outlet of the evaporator is connected to the suction port of the aspirator by piping, between the liquid outlet side of the first gas-liquid separator and the aspirator, and between the outlet of the evaporator and the suction port of the aspirator This pipe is provided with an internal heat exchanger capable of exchanging heat with each other.

  The refrigeration system according to claim 9 is characterized in that, in claim 8, the expander is any one of a scroll type, a turbine type, a rotary type, and a vane type.

  Therefore, according to the refrigeration system of claim 1, carbon dioxide is used as the refrigerant, the first compressor for compressing the refrigerant, the second compressor connected in series to the first compressor, and the second compression A gas cooler that cools the refrigerant that has been pressurized by the compressor, an expander that decompresses and expands the cooled refrigerant, and an aspirator are sequentially connected by piping, and a first gas-liquid separation provided between the expander and the aspirator The gas outlet side of the compressor and the suction side of the second compressor are connected by piping to constitute a gas injection cycle, while the liquid outlet side of the first gas-liquid separator is connected by piping to the aspirator and the first compressor Between the gas outlet side of the second gas-liquid separator provided between and the suction side of the first compressor, while the liquid outlet side of the second gas-liquid separator is connected to the evaporator via the throttle device Connect the piping and connect the outlet of the evaporator to the aspirator. In the refrigeration cycle connected to the inlet, heat exchange is possible between the pipe between the liquid outlet of the first gas-liquid separator and the aspirator and the pipe between the outlet of the evaporator and the suction port of the aspirator. Since an internal heat exchanger is provided, even if the liquid refrigerant cannot be sufficiently gasified in the evaporator and the refrigerant on the outlet side of the evaporator is in a gas-liquid two-phase state, The liquid refrigerant on the evaporator outlet side can be sufficiently gasified by the internal heat exchanger with the heat of the liquid refrigerant from the gas outlet of the first gas-liquid separator.

Accordingly, the work of the entire compressor can be sufficiently reduced while suppressing the temperature of the refrigerant flowing into the second compressor by the gas injection cycle, and the coefficient of performance (COP) and thus the refrigeration capacity can be improved.
Furthermore, if the refrigerant from the evaporator can be sufficiently gasified by the internal heat exchanger, the evaporator can be used in a gas-liquid two-phase state (dryness of 100% or less), so the heat exchange rate in the evaporator Can be kept at the maximum and the refrigerating capacity can be kept high, and this can also improve the coefficient of performance and thus the refrigerating capacity.

  According to the refrigeration system of the second aspect, the pipe between the gas cooler and the expander and the pipe between the gas outlet side of the first gas-liquid separator and the suction side of the second compressor are heated together. Since the exchangeable second internal heat exchanger is provided, the liquid refrigerant flowing from the gas cooler to the expander is used as the gas refrigerant from the gas outlet of the first gas-liquid separator by the second internal heat exchanger. Can be cooled.

And since the liquid refrigerant from the liquid outlet of the first gas-liquid separator becomes a low temperature and further becomes a low temperature by the internal heat exchanger, the liquid refrigerant flowing into the aspirator, that is, the driving flow of the aspirator can be further reduced to the final temperature. In addition, it is possible to further reduce the temperature of the liquid refrigerant flowing into the evaporator and reduce the pressure to promote the refrigeration performance in the evaporator.
Further, when the gas refrigerant from the gas outlet of the first gas-liquid separator is mixed with the refrigerant at the outlet of the first compressor, liquefaction of the refrigerant proceeds and liquid compression is likely to occur in the second compressor. Such a liquid compression can be prevented and the compressor can be protected by raising the temperature of the gas refrigerant from the gas outlet of the first gas-liquid separator with the second internal heat exchanger.

As a result, the coefficient of performance and thus the refrigeration capacity can be further improved.
According to the refrigeration system of claim 3, by using the power recovered by the expander for driving at least one of the first compressor and the second compressor, the energy lost in the expander is recovered. This can be applied to the driving force of the first compressor or the second compressor, and the coefficient of performance can be further improved.

Further, according to the refrigeration system of claim 4, by connecting a generator to the expander, the power recovered by the expander is converted into electric power, for example, by storing electricity, thereby recovering energy lost in the expander. The coefficient of performance can be further improved.
Further, according to the refrigeration system of claim 5, by connecting an electric motor connected to at least one of the first compressor and the second compressor to the expander, the energy lost in the expander is recovered. It can be applied directly to the driving force of the first compressor or the second compressor via the electric motor, and the deficiency can be applied to the driving force of the electric motor, so that the coefficient of performance and thus the refrigerating capacity can be further improved.

  According to the refrigeration system of claim 6, a rotating machine connected to at least one of the first compressor and the second compressor is connected to the expander, and the rotating machine is operated as an electric motor or a generator. By recovering the energy lost in the expander, it can be applied directly to the driving force of the first compressor or the second compressor via the rotating machine, and the deficit can be applied to the driving force of the electric motor, Alternatively, the surplus can be converted into electric power and used effectively, and the coefficient of performance and thus the refrigeration capacity can be further improved.

  Further, according to the refrigeration system of claim 7, the first compressor and the second compressor are any one of a scroll type, a turbine type, a rotary type, a swing type, a swash plate type, a screw type, and a vane type, and are expanded. Since the machine is one of the scroll type, turbine type, rotary type, and vane type, the coefficient of performance and thus the refrigeration capacity should be further improved while freely combining the first compressor, the second compressor and the expander. Can do.

  Further, according to the refrigeration system of claim 8, carbon dioxide is used as the refrigerant, and the scroll compressor that compresses the refrigerant, the gas cooler that cools the refrigerant pressurized by the scroll compressor, and the cooling An expander for decompressing and expanding the generated refrigerant and an aspirator are sequentially connected by piping, and a gas outlet side of the first gas-liquid separator provided between the expander and the aspirator and an intermediate pressure region of the scroll compressor are connected. A gas injection cycle is configured by pipe connection, while the gas outlet of the second gas-liquid separator provided between the aspirator and the scroll compressor is connected to the aspirator with the liquid outlet side of the first gas-liquid separator. While connecting the pipe side to the suction side of the scroll compressor, the liquid outlet side of the second gas-liquid separator is connected to the evaporator via a throttling device, and the outlet of the evaporator is connected to the suction of the aspirator. In a refrigeration cycle that is connected to a pipe, the inside of the pipe between the liquid outlet side of the first gas-liquid separator and the aspirator and the pipe between the outlet of the evaporator and the suction port of the aspirator can exchange heat with each other Since the heat exchanger is provided, even if the liquid refrigerant cannot be sufficiently gasified by the evaporator and the refrigerant at the outlet side of the evaporator is in a gas-liquid two-phase state, the evaporation The liquid refrigerant on the outlet side of the vessel can be sufficiently gasified with the heat of the liquid refrigerant from the gas outlet of the first gas-liquid separator by the internal heat exchanger.

As a result, the gas injection cycle can be simply configured with only one scroll compressor, and the work of the entire compressor can be sufficiently reduced while keeping the refrigerant temperature flowing into the intermediate pressure region of the scroll compressor low, and The heat exchange rate in the evaporator can be kept at the maximum, and the coefficient of performance and thus the refrigerating capacity can be improved.
Further, according to the refrigeration system of claim 9, since the expander is any one of the scroll type, the turbine type, the rotary type, and the vane type, the coefficient of performance, Further improvement in the refrigerating capacity can be achieved.

Embodiments of the present invention will be described below with reference to the drawings.
First, Example 1 will be described.
FIG. 1 shows a schematic configuration diagram of a refrigeration system according to Embodiment 1 of the present invention.
The refrigeration system according to the present invention is applied to various refrigeration / air conditioning cycles such as a vehicle air conditioner, a commercial air conditioner, a home heat pump, a water heater, and a heater.

As shown in the figure, in the refrigeration system according to the first embodiment of the present invention, carbon dioxide (CO ₂ ) is used as a refrigerant, and the first compressor 10 that compresses the refrigerant and the first compressor 10 have an intermediate pressure. A second compressor 12 that further boosts the pressure of the refrigerant that has been boosted up to, a gas cooler (gas cooler) 13 that cools the boosted refrigerant, and a gas cooler 13 that is located downstream of the gas cooler 13. An expander 14 that decompresses and expands the cooled refrigerant and an aspirator 20 are sequentially connected by piping. As the first compressor 10 and the second compressor 12, for example, any of a scroll type, a turbine type, a rotary type, a swing type, a swash plate type, a screw type, and a vane type is adopted. As the expander 14, For example, any of a scroll type, a turbine type, a rotary type, and a vane type is adopted, and these can be freely combined.

A first gas / liquid separator 15 is provided between the expander 14 and the aspirator 20, and the gas outlet side of the first gas / liquid separator 15 and the suction side of the second compressor 12 are connected to each other by piping. A so-called gas injection cycle is configured by being connected. On the other hand, the liquid outlet side of the first gas-liquid separator 15 is connected to the aspirator 20 by piping.
A second gas-liquid separator 16 is provided between the aspirator 20 and the first compressor 10, and the gas outlet side of the second gas-liquid separator 16 and the suction side of the first compressor 10 are piped. On the other hand, the liquid outlet side of the second gas-liquid separator 16 is connected to the evaporator 18 via a throttling device 17.

The aspirator 20 takes in the liquid refrigerant from the expander 14 as a driving flow from the suction port 21, and sucks the gas refrigerant from the evaporator 18 from the suction port 22, while increasing the pressure by decelerating the whole refrigerant with a diffuser. However, it has a function of discharging from the discharge port 23. Therefore, the outlet of the evaporator 18 is connected to the suction port 22 of the aspirator 20.
The piping between the liquid outlet side of the first gas-liquid separator 15 and the aspirator 20 and the piping between the outlet of the evaporator 18 and the suction port 22 of the aspirator 20 are internally arranged so that they can exchange heat with each other. A heat exchanger 30 is provided.

Hereinafter, the effect of the refrigeration system according to the first embodiment of the present invention configured as described above will be described.
The refrigerant compressed by the first compressor 10 is compressed by the second compressor 12 together with the gas refrigerant from the first gas-liquid separator 15 and flows into the gas cooler 13 as a high-temperature and high-pressure supercritical refrigerant. Then, the gas cooler 13 dissipates heat and is cooled.

The refrigerant that has exited the gas cooler 13 is expanded from a high pressure to an intermediate pressure by the expander 14. At this time, the temperature is lowered by adiabatic expansion, and energy is released as power by reducing the enthalpy. .
Since the refrigerant exiting the expander 14 is in a gas-liquid two-phase state, the refrigerant flows into the first gas-liquid separator 15 and is separated into gas refrigerant and liquid refrigerant. On the other hand, the liquid refrigerant passes through the internal heat exchanger 30 and flows into the suction port 21 of the aspirator 20. Then, the refrigerant flowing into the aspirator 20 becomes a driving flow, and by reducing the pressure, the gas refrigerant from the outlet of the evaporator 18 is sucked, and the whole refrigerant is discharged from the discharge port 23 while being pressurized by the diffuser. It flows into the liquid separator 16.

Since the refrigerant discharged from the discharge port 23 of the aspirator 20 is in a gas-liquid two-phase state, it is separated into a gas refrigerant and a liquid refrigerant in the second gas-liquid separator 16, and the gas refrigerant is transferred to the first compressor 10. On the other hand, the liquid refrigerant is slightly reduced in pressure to the evaporation pressure in the expansion device 17 and becomes low-temperature and low-pressure wet steam and flows into the evaporator 18.
The refrigerant that has flowed into the evaporator 18 is gasified by exchanging heat with the atmosphere, and is further completely gasified by the internal heat exchanger 30 and sucked into the aspirator 20 from the suction port 22, and as described above, the internal heat exchanger 30. The pressure is increased by a diffuser together with the refrigerant from

Specifically, due to the action of the aspirator 20, the refrigerant becomes a pressure higher than the evaporation pressure in the evaporator 18 and flows into the second gas-liquid separator 16. Therefore, the suction pressure of the first compressor 10 increases, and the power of the first compressor 10 and the second compressor 12 necessary for compression can be reduced. Thereby, the coefficient of performance (COP) of the refrigeration system can be improved.
Further, in the refrigeration system according to the present invention, the piping between the liquid outlet side of the first gas-liquid separator 15 and the aspirator 20 and the piping between the outlet of the evaporator 18 and the suction port 22 of the aspirator 20 are internally provided. Since the heat exchanger 30 is provided, the temperature of the refrigerant from the evaporator 18 is increased by the heat of the refrigerant from the first gas-liquid separator 15, and gasification is promoted.

  Therefore, for example, if the heat exchange with the atmosphere in the evaporator 18 is not sufficient, the refrigerant sucked into the aspirator 20 may be in a gas-liquid two-phase state. Even in such a case, the evaporator The refrigerant from 18 can be sucked into the aspirator 20 as a gas refrigerant sufficiently gasified by the internal heat exchanger 30, and the pressure can be increased well together with the refrigerant from the first gas-liquid separator 15.

Further, here, since the gas outlet side of the first gas-liquid separator 15 and the suction side of the second compressor 12 are connected by pipes to form a so-called gas injection cycle, the second compressor 12 is also combined. It is possible to keep the temperature of the refrigerant flowing into the tank low. As a result, when carbon dioxide (CO ₂ ) is used as the refrigerant, the temperature of the discharge gas from the second compressor 12 tends to rise remarkably because the evaporation temperature is low. It is possible to suppress the temperature rise, prevent a decrease in the reliability of the device, and improve the coefficient of performance (COP) of the refrigeration system.

Accordingly, the suction pressure of the first compressor 10 is sufficiently increased while the temperature of the refrigerant flowing into the second compressor 12 is kept low by the gas injection cycle, and the power of the first compressor 10 and the second compressor 12 is increased. Can be reliably reduced, and the coefficient of performance (COP) of the refrigeration system, and thus the refrigeration capacity can be improved.
In addition, when the refrigerant from the evaporator 18 can be sufficiently gasified by the internal heat exchanger 30 as described above, the evaporator 18 can be used in a gas-liquid two-phase state (dryness of 100% or less). It is possible to keep the heat exchange rate in the vessel 18 at the maximum and keep the refrigeration capacity high, and it is possible to improve the coefficient of performance (COP) of the refrigeration system and thus the refrigeration capacity.

Here, referring to FIG. 2, a ph diagram (pressure-enthalpy diagram, Mollier diagram) of the refrigeration system according to the present invention configured as described above is shown.
In the figure, reference signs a to n correspond to the respective parts denoted by reference signs a to n in FIG. 1, reference signs a, b, c, f, g, and h denote gas injection cycles, and reference signs g to “n” indicates a cycle from the suction port 21 of the aspirator 20 to the suction port 22 of the aspirator 20 through the second gas-liquid separator 16, the evaporator 18 and the internal heat exchanger 30, that is, an aspirator cycle.

By configuring the gas injection cycle and the aspirator cycle in this way, it is possible to improve the coefficient of performance (COP) of the refrigeration system, and thus the refrigeration capacity.
Referring to FIG. 3, there is shown a schematic configuration diagram of a modification of the refrigeration system according to the first embodiment. Hereinafter, a modification of the refrigeration system according to the first embodiment will be described. The description of the same parts as those in FIG. 1 is omitted.

  As described above, the expander 14 is configured to be able to release energy as power by expanding the cooled refrigerant under reduced pressure, and in this modification, the refrigeration system includes the expander 14 and, for example, the first The second compressor 12 is connected to the compressor 12 by a drive shaft 50 via a motor / generator (M / G) (rotary machine, electric motor) 60, and is recovered by the power recovered by the expander 14 via the motor / generator 60. 12 can be driven. That is, the expander 14 bears a part of the driving force of the second compressor 12.

  Specifically, when the driving force required for the second compressor 12 is insufficient by the power of the expander 14 according to the driving force required for the second compressor 12, the motor / generator 60 functions as a motor. If the deficient driving force can be supplied to the second compressor 12, while the power of the expander 14 is excessive with respect to the driving force required for the second compressor 12, the motor The generator 60 functions as a generator, generates electric power with a surplus driving force, converts the power recovered by the expander 14 into electric power, and can store, for example, electricity.

  Thus, in the refrigeration system according to the modification, the power recovered by the expander 14 can be applied to the driving force of the second compressor 12 while compensating for the deficiency by the motor function of the motor generator 60, Alternatively, it can be converted into electric energy by the generator function of the motor / generator 60, and the energy lost in the expander 14 can be recovered and used effectively.

The motor / generator 60 may have only a function as a motor (electric motor) and only make up for the shortage of power recovered by the expander 14. Even in this case, the expander 14 may be used. It is possible to recover and effectively use energy lost in the process.
As a result, the coefficient of performance (COP) of the refrigeration system, and thus the refrigeration capacity, can be further improved.

Here, the expander 14 and, for example, the second compressor 12 are connected, but the expander 14 and, for example, the first compressor 10 may be connected by a drive shaft.
As another modification, a generator (G) (generator) 70 is connected to the expander 14 via a drive shaft 50 ′ and recovered by the expander 14 as shown in a part of the configuration in FIG. 4. The generator 70 may be operated with power to generate power, and the generated power may be stored, for example.

Further, when the second compressor 12 can be sufficiently driven, for example, only by the power of the expander 14, as another modification, as shown in FIG. For example, the second compressor 12 may be directly connected to the drive shaft 50 ″, and the second compressor 12 may be directly driven by the power recovered by the expander 14.
Even if it does in this way, it is possible to collect | recover the energy lost in the expander 14, and to utilize it effectively, and can aim at the further improvement of the coefficient of performance (COP) of a refrigerating system, and also refrigerating capacity.

Next, Example 2 will be described.
FIG. 6 shows a schematic configuration diagram of a refrigeration system according to Embodiment 2 of the present invention.
The refrigeration system according to the second embodiment is different from the first embodiment in that the second internal heat exchanger 40 is provided. Hereinafter, description of the same parts as those in the first embodiment is omitted, and the second embodiment is omitted. The description will focus on the parts different from 1.

As shown in the figure, in the refrigeration system according to Embodiment 2 of the present invention, the piping between the gas cooler 13 and the expander 14, the gas outlet side of the first gas-liquid separator 15, and the second compressor A second internal heat exchanger 40 capable of exchanging heat with each other is provided in a pipe between the intake side and the intake side.
When the second internal heat exchanger 40 is provided in this way, the liquid refrigerant flowing from the gas cooler 13 to the expander 14 is cooled by the gas refrigerant from the first gas-liquid separator 15, and as a result. The liquid refrigerant at the inlet of the internal heat exchanger 30 from the first gas-liquid separator 15 is cooled.

  When the liquid refrigerant from the first gas-liquid separator 15 is cooled, the liquid refrigerant is further cooled by the internal heat exchanger 30, and the driving flow of the aspirator 20 can be further lowered. If the driving flow of the aspirator 20 can be made lower in this way, the liquid refrigerant finally flowing into the evaporator 18 can be further reduced in temperature and depressurized, and the refrigeration performance by the evaporator 18 can be further improved. Can be promoted.

  Further, when the gas refrigerant from the gas outlet of the first gas-liquid separator 15 is mixed with the refrigerant at the outlet of the first compressor 10, liquefaction of the refrigerant proceeds and liquid compression is likely to occur in the second compressor 12. However, by increasing the temperature of the gas refrigerant from the gas outlet of the first gas-liquid separator 15 by the second internal heat exchanger 40, such liquid compression can be prevented, and the second compressor 12 Can be protected.

As a result, the coefficient of performance (COP) of the refrigeration system, and thus the refrigeration capacity, can be further improved.
Also in the second embodiment, as in the first embodiment, as a modified example, the expander 14 and, for example, the second compressor 12 are connected by the drive shaft 50 via the motor / generator (M / G) 60, and the refrigeration system. As another modification, the generator (G) 70 is connected to the expander 14 via the drive shaft 50 ′, or as another modification, the expander 14 and the second compressor 12 are connected. May be directly connected by a drive shaft 50 "to constitute a refrigeration system. The expander 14 and, for example, the first compressor 10 may be connected by a drive shaft.

As a result, the energy lost in the expander 14 can also be recovered and used effectively, and the coefficient of performance (COP) of the refrigeration system and thus the refrigeration capacity can be further improved.
Next, Example 3 will be described.
FIG. 7 shows a schematic configuration diagram of a refrigeration system according to Embodiment 3 of the present invention.

The refrigeration system according to the third embodiment is different from the first and second embodiments in that only one scroll compressor 100 is provided instead of the first compressor 10 and the second compressor 12. Hereinafter, the description of the same parts as those in the first and second embodiments will be omitted, and the description will focus on parts different from the first and second embodiments.
As shown in the figure, in the refrigeration system according to Embodiment 3 of the present invention, the gas outlet side of the first gas-liquid separator 15 and the intermediate pressure region of the scroll compressor 100 are communicated with each other by pipe connection, so-called gas. An injection cycle is configured. That is, by using the scroll compressor 100, the first compressor 10 and the second compressor 12 are realized by one compressor.

As the expander 14, for example, a scroll type, a turbine type, a rotary type, or a vane type is adopted, and these can be freely combined.
As a result, as described above, even when carbon dioxide (CO ₂ ) is used as the refrigerant, the temperature rise of the refrigerant is suppressed, and the apparatus has a simple configuration in which only one scroll compressor 100 is provided. It is possible to prevent a decrease in reliability and improve the coefficient of performance (COP) of the refrigeration system.

  Also in the third embodiment, as in the first and second embodiments, as a modified example, the expander 14 and the scroll compressor 100 are coupled by a drive shaft 50 via a motor / generator (M / G) 60 to be refrigerated. The system may be configured, and as another modified example, the generator (G) 70 is connected to the expander 14 via the drive shaft 50 ', or as another modified example, the expander 14 and the scroll compressor 100 may be directly connected to the drive shaft 50 ″ to constitute a refrigeration system.

As a result, the energy lost in the expander 14 can also be recovered and used effectively, and the coefficient of performance (COP) of the refrigeration system and thus the refrigeration capacity can be further improved.
The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 is a schematic configuration diagram of a refrigeration system according to Embodiment 1 of the present invention. It is a ph diagram of the refrigeration system concerning the present invention. FIG. 3 is a schematic configuration diagram of a refrigeration system according to a modified example of the first embodiment. It is a figure which shows a part of structure of the refrigeration system which concerns on the other modification of Example 1. FIG. FIG. 10 is a diagram illustrating a part of the configuration of a refrigeration system according to still another modification of the first embodiment. It is a schematic block diagram of the refrigeration system which concerns on Example 2 of this invention. It is a schematic block diagram of the refrigeration system which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st compressor 12 2nd compressor 13 Gas cooler 14 Expander 15 1st gas-liquid separator 16 2nd gas-liquid separator 18 Evaporator 20 Aspirator 30 Internal heat exchanger 40 2nd internal heat exchanger 60 Motor Generator 70 Generator 100 Scroll compressor

Claims (9)

A first compressor that compresses the refrigerant using carbon dioxide, a second compressor connected in series to the first compressor, and a gas cooler that cools the refrigerant pressurized by the second compressor And an expander that decompresses and expands the cooled refrigerant, and an aspirator are sequentially connected by piping,
A first gas-liquid separator is provided between the expander and the aspirator, and a gas outlet side of the first gas-liquid separator and a suction side of the second compressor are connected by piping, while the first gas-liquid separator is connected to the first gas-liquid separator. Connect the liquid outlet side of the liquid separator to the aspirator by piping,
A second gas-liquid separator is provided between the aspirator and the first compressor, and the gas outlet side of the second gas-liquid separator and the suction side of the first compressor are connected by piping, 2 The liquid outlet side of the gas-liquid separator is connected to the evaporator through a throttle device, and the outlet of the evaporator is connected to the suction port of the aspirator.
An internal heat exchanger capable of exchanging heat with each other is provided in a pipe between the liquid outlet side of the first gas-liquid separator and the aspirator and a pipe between the outlet of the evaporator and the suction port of the aspirator. A refrigeration system characterized by   Furthermore, a second internal space that can exchange heat with each other between a pipe between the gas cooler and the expander and a pipe between the gas outlet side of the first gas-liquid separator and the suction side of the second compressor. The refrigeration system according to claim 1, further comprising a heat exchanger.   The refrigeration system according to claim 1 or 2, wherein power recovered by the expander is used to drive at least one of the first compressor and the second compressor.   The refrigeration system according to claim 1, wherein a generator is connected to the expander.   The refrigeration system according to claim 1 or 2, wherein an electric motor connected to at least one of the first compressor and the second compressor is connected to the expander.   Connecting the rotating machine connected to at least one of the first compressor and the second compressor to the expander, and operating the rotating machine as an electric motor or a generator according to the required power of each other. The refrigeration system according to claim 1 or 2, characterized by the above.   The first compressor and the second compressor are scroll type, turbine type, rotary type, swing type, swash plate type, screw type, vane type, and the expander is scroll type, turbine type, rotary type. The refrigeration system according to any one of claims 1 to 6, wherein the refrigeration system is of a vane type. A scroll compressor that compresses the refrigerant using carbon dioxide as a refrigerant, a gas cooler that cools the refrigerant pressurized by the scroll compressor, an expander that decompresses and expands the cooled refrigerant, an aspirator, Connect the pipes in sequence,
A first gas-liquid separator is provided between the expander and the aspirator, and a gas outlet side of the first gas-liquid separator and an intermediate pressure region of the scroll compressor are connected by piping. Connect the liquid outlet side of the gas-liquid separator to the aspirator by piping,
A second gas-liquid separator is provided between the aspirator and the scroll compressor, and the gas outlet side of the second gas-liquid separator and the suction side of the scroll compressor are connected by piping. 2 The liquid outlet side of the gas-liquid separator is connected to the evaporator through a throttle device, and the outlet of the evaporator is connected to the suction port of the aspirator.
An internal heat exchanger capable of exchanging heat with each other is provided in a pipe between the liquid outlet side of the first gas-liquid separator and the aspirator and a pipe between the outlet of the evaporator and the suction port of the aspirator. A refrigeration system characterized by   The refrigeration system according to claim 8, wherein the expander is one of a scroll type, a turbine type, a rotary type, and a vane type.

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