JP5656691B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus using a refrigeration cycle.

Application of low GWP refrigerants to refrigeration and air-conditioning equipment has been accelerated from the viewpoint of reducing environmental impact. An example of such a refrigerant candidate is carbon dioxide.
As a conventional refrigeration apparatus using carbon dioxide as a refrigerant, for example, it has a refrigeration circuit composed of a compressor (1), evaporators (4) and (14), and expansion valves (3) and (13). In a carbon dioxide refrigerator that employs carbon dioxide as a carbon dioxide refrigerator characterized in that the compressor (1) is constituted by a swing type rotary compressor (for example, Patent Document 1).

JP 2001-65888 A (Claim 1)

However, when carbon dioxide is used as the refrigerant, in a single-stage vapor compression refrigeration cycle, the operating pressure ratio becomes very high as the temperature difference between the outside air temperature and the cooling temperature increases, and the energy efficiency of the positive displacement compressor There has been a problem of lowering.
For example, in the case of performing an operation of maintaining the outside air temperature at 32 ° C. and the cooling temperature (internal temperature) −40 ° C., the operating pressure ratio increases to 8 or more.

A binary refrigeration cycle is known as a configuration of a refrigeration apparatus that improves the energy efficiency of a positive displacement compressor. In the two-way refrigeration cycle, the operating pressure ratio can be reduced, but when the intake gas temperature increases, the discharge gas temperature increases and the operating range is limited.
In a displacement type compressor that does not have an inherent compression ratio such as a reciprocating type or a rotary type, it is necessary to lower the intake gas temperature in the operation where the discharge temperature becomes high, and the operating range is limited. was there.

  The present invention has been made to solve the above-described problems, and provides a refrigeration apparatus that can improve the energy efficiency of a compressor when carbon dioxide is used as a refrigerant. Moreover, the freezing apparatus which can expand an operation range is obtained.

A refrigeration apparatus according to the present invention includes a first refrigerant circuit that sequentially connects a first compressor, a first condenser, a first expansion mechanism, and a first evaporator to circulate the first refrigerant, a second compressor, A second refrigerant circuit that sequentially connects a second condenser, a second expansion mechanism, and a second evaporator, and circulates a second refrigerant, the first refrigerant in the first evaporator, and the second refrigerant In the refrigeration apparatus for exchanging heat with the second refrigerant in the condenser, carbon dioxide is used as the second refrigerant, the second compressor is constituted by a scroll compressor, and the first evaporation of the first refrigerant circuit is performed. An intermediate cooler for exchanging heat between the first refrigerant between the second compressor and the first compressor and the second refrigerant between the second compressor and the second condenser in the second refrigerant circuit The second refrigerant circuit depressurizes part of the second refrigerant flowing out of the intermediate cooler, and Those having a injection circuit for flowing into the compression chamber of the scroll compressor.

  In the present invention, the first refrigerant circuit and the second refrigerant circuit constitute a binary refrigeration cycle, and the compressor of the second refrigerant circuit using carbon dioxide refrigerant is constituted by a scroll compressor having an inherent compression ratio. The energy efficiency of the compressor can be improved.

It is a figure which shows the freezing apparatus in Embodiment 1 of this invention. It is a longitudinal cross-sectional schematic diagram of the scroll compressor in Embodiment 1 of this invention. It is a top view schematic diagram in the state where fixed scroll 101 and rocking scroll 102 in Embodiment 1 of the present invention were combined. It is a top view schematic diagram in the state where fixed scroll 101 and rocking scroll 102 in Embodiment 1 of the present invention were combined. It is a top view schematic diagram in the state where fixed scroll 101 and rocking scroll 102 in Embodiment 1 of the present invention were combined. It is a figure which shows the refrigerant system in Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a refrigeration apparatus in Embodiment 1 of the present invention.
The refrigeration apparatus in the present embodiment includes a high-source side refrigerant circuit (refrigeration cycle) and a low-source-side refrigerant circuit (refrigeration cycle).
The high-source side refrigerant circuit is a closed loop in which a high-side compressor 1, a high-side condenser 2, a high-side main LEV (electronic expansion valve) 3, a cascade condenser 4, and an intercooler 6 are sequentially connected. Configure. In the high-side refrigerant circuit, an HFC-based refrigerant not containing chlorine is used as a working fluid.
The low-side refrigerant circuit is configured in a closed loop by sequentially connecting the low-side compressor 5, the intermediate cooler 6, the cascade condenser 4, the low-side main LEV 7, and the low-side evaporator 8. In the low-side refrigerant circuit, carbon dioxide refrigerant is used as a working fluid.
In the cascade condenser 4, the low-source side refrigerant and the high-source side refrigerant exchange heat.
Also in the intercooler 6, heat exchange occurs between the low-side refrigerant and the high-side refrigerant.
By such heat exchange, the low-source-side refrigerant is liquefied and the high-source-side refrigerant is evaporated, thereby constituting a two-component refrigeration cycle (two-component refrigeration apparatus).

The “higher refrigerant circuit” corresponds to the “first refrigerant circuit” in the present invention.
The “low refrigerant circuit” corresponds to the “second refrigerant circuit” in the present invention.
The “higher compressor 1” corresponds to the “first compressor” in the present invention.
Further, the “high-end condenser 2” corresponds to the “first condenser” in the present invention.
Further, the “higher main LEV3” corresponds to the “first expansion mechanism” in the present invention.
The “cascade capacitor 4” corresponds to the “first evaporator” and the “second condenser” in the present invention.
The “low-source compressor 5” corresponds to the “second compressor” in the present invention.
Further, the “low original side main LEV7” corresponds to the “second expansion mechanism” in the present invention.
Further, the “low-evaporator 8” corresponds to the “second evaporator” in the present invention.
Further, the “higher refrigerant” corresponds to the “first refrigerant” in the present invention.
Further, the “low refrigerant side refrigerant” corresponds to the “second refrigerant” in the present invention.

Further, the low-side refrigerant circuit includes an injection circuit 11 that decompresses a part of the low-side refrigerant flowing out from the intercooler 6 and flows into the compression chamber of the low-side compressor 5. .
This injection circuit 11 includes a branch pipe that branches downstream from the intercooler 6 and connects to the low-end compressor 5, a variable-opening injection LEV 9 that depressurizes the refrigerant flowing through the injection circuit 11, and an injection. An injection solenoid valve 10 for opening and closing the flow path of the circuit 11 is provided.
Further, a temperature detection means (not shown) for detecting the temperature of the refrigerant discharged from the low-side compressor 5 is provided in the discharge pipe of the low-side compressor 5. This temperature detection means is composed of, for example, a thermocouple or a thermistor.
The opening degree of the injection LEV 9 is set according to the temperature detected by the temperature detecting means. Details of the operation will be described later.

  The “LEV 9 for injection” corresponds to the “pressure reduction mechanism” in the present invention.

The low-side compressor 5 in the present embodiment is configured by a scroll compressor. A scroll compressor has a ratio of a suction volume (described later) to a discharge volume (described later) (hereinafter referred to as “built-in volume ratio”) geometrically determined, and the built-in volume ratio is determined to be a constant value of 1 or more. This is a compression ratio type compressor.
The low-source compressor 5 (hereinafter also referred to as “scroll compressor”) in the present embodiment has a built-in volume ratio set to 2.0 or less. For example, the built-in volume ratio is set to an arbitrary value between 1.2 and 2.0.
Next, details of the scroll compressor will be described.

FIG. 2 is a schematic longitudinal sectional view of the scroll compressor according to Embodiment 1 of the present invention.
The scroll compressor sucks the refrigerant circulating through the low-side refrigerant circuit, compresses it, and discharges it as a high-temperature and high-pressure state.
This scroll compressor is composed of a compression unit including a fixed scroll 101 and a swing scroll 102 and a drive unit including an electric motor 112 and the like. These compression unit and drive unit are accommodated in the shell 100.
The shell 100 is an airtight container, and a lower portion thereof is an oil sump 115 for storing lubricating oil. A suction pipe 118 for sucking refrigerant gas is connected to the middle part of the shell 100. A discharge pipe 117 for discharging the refrigerant gas is connected to the upper part of the shell 100.

  The compression unit includes a swing scroll 102, a fixed scroll 101, a frame 103, and the like. As shown in FIG. 2, the orbiting scroll 102 is arranged on the lower side, and the fixed scroll 101 is arranged on the upper side. In addition, a thrust plate 107 that supports the swing scroll 102 is provided between the swing scroll 102 and the frame 103.

The fixed scroll 101 is formed with a spiral protrusion 101a erected on one surface. The swing scroll 102 is also provided with a spiral protrusion 102a that is erected on one surface and has substantially the same shape as the spiral protrusion 101a.
The swing scroll 102 and the fixed scroll 101 are mounted in the shell 100 by combining the spiral protrusion 101a and the spiral protrusion 102a with each other.
In a state where the swing scroll 102 and the fixed scroll 101 are combined, the winding direction of the spiral protrusion 101a and the spiral protrusion 102a is opposite to each other. A plurality of compression chambers whose volumes change relatively are formed between the spiral protrusion 101a and the spiral protrusion 102a. Details of the compression chamber will be described later.
Further, at the end of the spiral protrusion 101a of the fixed scroll 101 and the end of the spiral protrusion 102a of the orbiting scroll 102, for example, PPS (polyphenylene sulfide resin) is used as a material, and a seal member 105 that seals between the compression chambers is provided. Yes.

The fixed scroll 101 is fixed to the frame 103 with bolts or the like. A discharge port 116 for discharging the compressed and high-pressure refrigerant gas is formed in the central portion of the fixed scroll 101. The compressed and high pressure refrigerant gas is discharged into a discharge space provided in the upper part of the fixed scroll 101.
In addition, an injection port 120 that communicates the intermediate pressure compression chamber and the injection circuit 11 is provided at a position where an intermediate pressure compression chamber (described later) of the fixed scroll 101 is formed. The number of injection ports 120 can be set as appropriate.

The swinging scroll 102 performs a revolving orbiting motion without rotating with respect to the fixed scroll 101 by an Oldham ring 104 for preventing the rotating motion.
A hollow cylindrical boss portion is formed at a substantially central portion of the surface (thrust surface) opposite to the surface on which the spiral protrusion 102a is formed of the orbiting scroll 102. The boss portion is provided with a journal bearing, and a bush 106 is provided inside the journal bearing.
The swinging scroll 102 is transmitted with driving force from the main shaft 108 via the bush 106 and the journal bearing.

  The drive unit includes a rotor 109, a stator 110, a main shaft 108 that is a rotating shaft, and the like. The rotor 109 is fixed to the main shaft 108 and is driven to rotate when the energization of the stator 110 is started to rotate the main shaft 108. The stator 110 is fixed to the inner peripheral surface of the shell 100.

The main shaft 108 rotates with the rotation of the rotor 109 to turn the swing scroll 102.
An upper portion 111 of the main shaft 108 is supported by a main bearing provided on the frame 103.
On the other hand, the lower part of the main shaft 108 is rotatably supported by ball bearings. This ball bearing is press-fitted and fixed in a bearing housing portion formed at the center of a sub-frame 114 provided at the lower part of the shell 100. The subframe 114 is provided with a positive displacement oil pump 113.
Lubricating oil sucked by the oil pump is sent to each sliding portion through an oil hole 108a formed inside the main shaft 108 and the like.

With such a configuration, when the main shaft 108 is rotationally driven by the electric motor 112, the orbiting scroll 102 whose rotation is suppressed by the Oldham ring 104 performs a revolving motion. This starts the inhalation process.
The refrigerant (carbon dioxide) that flows into the shell 100 is sucked into the compression chamber, moves to the center of the orbiting scroll 102 by the revolving motion of the orbiting scroll 102, and the volume is reduced. Through this process, the refrigerant sucked into the compression chamber is compressed. The compressed refrigerant passes through the discharge port 116 of the fixed scroll 101 and flows into the discharge space. Then, it is discharged from the shell 100 via the discharge pipe 117.

  Next, details of the compression chamber formed by combining the fixed scroll 101 and the orbiting scroll 102 will be described with reference to FIGS.

3 to 5 are schematic top views in a state where the fixed scroll 101 and the swing scroll 102 are combined in the first embodiment of the present invention.
FIG. 3 shows a swirl state when the suction of the refrigerant is completed.
As shown in FIG. 3, the number of spirals of the fixed scroll 101 and the orbiting scroll 102 in this embodiment is set to 2.5 or more.
When the suction of the refrigerant is completed, a pair of suction side compression chambers A and B are formed at the outermost side in the radial direction, and a discharge side compression chamber E that opens to the discharge port 116 is formed at the center.
The suction volume is obtained by adding the volumes of the suction side compression chamber A and the suction side compression chamber B when the suction of the refrigerant is completed.

Further, an intermediate pressure compression chamber C, which is a compression chamber that does not communicate with either the suction side compression chamber A or the discharge side compression chamber E, is formed on the suction side compression chamber A side.
An intermediate pressure compression chamber D, which is a compression chamber that does not communicate with either the suction side compression chamber B or the discharge side compression chamber E, is formed on the suction side compression chamber B side.
In the present embodiment, since the number of spirals is set to 2.5 or more, the intermediate pressure compression chambers C and D are formed regardless of the revolution angle of the swing scroll 102.

FIG. 4 shows a fitted state immediately before the sucked refrigerant is sequentially compressed and discharged.
By the revolving motion of the orbiting scroll 102, each compression chamber is moved to the center side while reducing its volume.
And in the state just before discharge, the discharge side compression chambers F and G are formed.
The injection port 120 is in communication with the intermediate pressure compression chambers C and D.
The discharge volume is obtained by adding the volumes of the discharge side compression chamber F and the discharge side compression chamber G immediately before discharging the compressed refrigerant.
In the present embodiment, the built-in volume ratio obtained by dividing the suction volume at the completion of suction by the discharge volume immediately before discharge is set to 1.2 to 2.0.

FIG. 5 shows a swirl fit state when the rotation angle is advanced from the fit state of FIG.
As indicated by the arrows in FIG. 5, the refrigerant compressed in the discharge side compression chamber F is discharged to the discharge port 116 from the notch portion at the center of the swing scroll 102.
On the other hand, as indicated by the oblique line of the discharge port 116, the discharge port 116 opens into the discharge side compression chamber F, so that the refrigerant compressed in the discharge side compression chamber F is discharged from the discharge port 116 diagonal portion.
That is, by providing a notch inside the center portion of the orbiting scroll 102 and adjusting the position of the discharge port 116, the built-in volume ratio becomes 1.2 to 2.0 from the volume at the completion of the suction. It is set so that the discharge side compression chambers F and G are discharged at the time.

  Next, the operation and action of the first embodiment will be described.

First, the operation at the time of starting the refrigeration apparatus will be described.
When starting the refrigerating apparatus in the first embodiment, first, the high-end compressor 1 of the high-end refrigerant circuit is started (starts operation), and then the low-end refrigerant circuit is started. .
The low-source side refrigerant circuit is started by starting the low-source side compressor 5 of the low-source-side refrigerant circuit after the low-source side in the cascade capacitor 4 becomes equal to or lower than a predetermined temperature.
By this activation control, the high-side compressor 1 of the high-side refrigerant circuit is operated to circulate the refrigerant, thereby cooling the low-side side of the cascade capacitor 4. This has the effect of preventing the high-pressure abnormal pressure increase on the low side due to the increase in the condensation load.

Next, the flow of the refrigerant in the refrigeration apparatus will be described.
When the high-end compressor 1 is started, refrigerant is sucked into the high-end compressor 1 and high-temperature and high-pressure refrigerant is introduced into the high-end condenser 2.
In the high-end side condenser 2, it is cooled with air at an outside temperature by a blower such as a fan, and the refrigerant condenses. At the outlet of the high-end side condenser 2, it flows as a high-pressure liquid refrigerant.
The liquid refrigerant expands and flows into the cascade condenser 4 by the high-side main LEV 3.
In the cascade condenser 4, heat is taken from the low-source side refrigerant and evaporated. Further, the intermediate cooler 6 also evaporates by taking heat from the low-source side refrigerant. The evaporated refrigerant is sucked into the high-end compressor 1 again. The high-end side performs this series of operations.

After the low-side temperature in the cascade capacitor 4 reaches a predetermined value or less, the low-side compressor 5 is started.
When the low-side compressor 5 is started, the refrigerant is sucked into the low-side compressor 5, and the high-temperature and high-pressure refrigerant is introduced into the cascade condenser 4 through the intermediate cooler 6.
Since the inside of the cascade capacitor 4 is cooled by the high-side refrigerant circuit operating in advance, there is an effect that the high pressure level can be prevented from being abnormally boosted by the condensation load.
In the cascade capacitor 4, the low-side refrigerant is liquefied by exchanging heat with the high-side refrigerant.
The liquid refrigerant is expanded by the low-side main LEV 7 and is evaporated in the low-side evaporator 8 by exchanging heat with the internal air of the temperature adjustment target. The evaporated refrigerant is sucked again into the low-side compressor 5. The low element side performs this series of operations.

Here, when the operating pressure ratio, which is the ratio of the high-pressure side pressure to the low-pressure side pressure, in the low-side refrigerant circuit becomes high, the intermediate pressure compression chambers C and D of the low-side compressor 5 from the injection circuit 11 are increased. Liquid refrigerant is injected into the inside. This operating pressure ratio can also be obtained from the ratio of the outside air temperature to the evaporation temperature.
For example, the liquid refrigerant is injected by setting the opening degree of the injection LEV 9 in accordance with the operating pressure ratio.

  Further, when the operating pressure ratio increases, the discharge temperature of the low-side compressor 5 (the temperature of the discharged refrigerant) also increases. Thus, the opening degree of the injection LEV 9 may be set.

  In addition, although the case where the opening degree of LEV9 for injection was set here was demonstrated, this invention is not limited to this. For example, the injection solenoid valve 10 may be opened when the opening of the injection LEV 9 is constant and the operating pressure ratio or the discharge temperature exceeds a predetermined value.

(effect)
As described above, in the present embodiment, the high-side compressor 1, the high-side condenser 2, the high-side main LEV 3, and the cascade condenser 4 are sequentially connected to circulate the high-side refrigerant. A low-side refrigerant circuit, a low-side compressor, a cascade condenser 4, a low-side main LEV 7 and a low-side evaporator 8 are sequentially connected to circulate the low-side refrigerant. And a high temperature side refrigerant in the cascade capacitor 4 and a low temperature side refrigerant in the cascade capacitor 4 are configured to exchange heat. Then, carbon dioxide was used as the low-side refrigerant, and the low-side compressor 5 was constituted by a scroll compressor. For this reason, compared with a single-stage refrigeration cycle, the operating pressure ratio can be reduced, and the energy efficiency of the low-side compressor 5 can be improved.

For example, in the case of refrigeration rated operation in which the outside air temperature is maintained at 32 ° C. and the cooling temperature (internal temperature) −40 ° C., the binary refrigeration apparatus is configured as in the present embodiment, and When the refrigerant is applied, the operation is performed at an operation pressure ratio of about 2.6.
Moreover, in the case of the refrigeration rated operation which maintains the outside air temperature at 32 ° C. and the cooling temperature (internal temperature) −5 ° C., the operation pressure ratio is about 1.9.

Moreover, in this Embodiment, the built-in volume ratio of the scroll compressor which comprises the low original side compressor 5 was set to 2.0 or less (for example, 1.2-2.0).
For this reason, appropriate compression can be performed and energy efficiency can be improved.

Further, in the present embodiment, the scroll compressor forms a plurality of compression chambers by combining the spiral protrusions of the fixed scroll and the spiral protrusions of the orbiting scroll that revolves, and the suction side compression chambers A, B, and Intermediate pressure compression chambers C and D that do not communicate with any of the discharge side compression chambers E are formed regardless of the revolution angle of the orbiting scroll 102.
As described above, even when the built-in volume ratio is relatively small of 2.0 or less, the intermediate pressure compression chambers C and D are formed.
By forming these intermediate pressure compression chambers C and D, the differential pressure between the compression chambers can be reduced, so that internal leakage can be reduced, over compression loss can be reduced, and energy efficiency can be increased.
Even if the operation pressure ratio is reduced by configuring the binary refrigeration apparatus as in the present embodiment, the differential pressure is large in the case of carbon dioxide refrigerant. For example, in the case of an operation in which the outside air temperature is maintained at 32 ° C. and the cooling temperature (internal temperature) −5 ° C., the differential pressure is as large as 2.4 MPa.
Even when such a pressure difference between the suction side and the discharge side is large, by forming the intermediate pressure compression chambers C and D, the differential pressure between the compression chambers can be reduced, so that internal leakage can be reduced and energy can be reduced. Efficiency can be increased.

Further, in the present embodiment, an injection circuit 11 is provided that decompresses a part of the refrigerant flowing out from the intercooler 6 and flows it into the compression chamber of the low-side compressor 5.
For this reason, the discharge refrigerant | coolant temperature of the low original side compressor 5 can be reduced, and an operating range can be expanded.

In the present embodiment, an injection port 120 that communicates the intermediate pressure compression chambers C and D of the scroll compressor and the injection circuit 11 is provided.
For this reason, refrigerant injection into the intermediate pressure compression chambers C and D can be performed regardless of the suction injection. Therefore, the refrigerant temperature discharged from the low-source compressor 5 can be reduced, and the operating range can be expanded.
In addition, since the intermediate pressure compression chambers C and D are not in communication with the suction side compression chambers A and B and the discharge side compression chamber E, the injected liquid refrigerant does not flow into the shell 100. Therefore, it is possible to prevent the temperature of the lubricating oil supplied to each part from the oil sump 115 in the compressor from being lowered, and there is an effect that the reliability of the sliding part such as the bearing part can be secured.

In the present embodiment, the opening degree of the injection LEV 9 is set according to the operating pressure ratio, which is the ratio of the high-pressure side pressure to the low-pressure side pressure in the low-source side refrigerant circuit.
For this reason, the liquid refrigerant to be injected can be adjusted in accordance with an increase in the discharge pipe temperature of the low-source compressor 5, and the discharge pipe temperature can be adjusted.
Therefore, the refrigerant temperature discharged from the low-source compressor 5 can be reduced, and the operating range can be expanded.

Moreover, in this Embodiment, the opening degree of LEV9 for injection is set according to the temperature of the refrigerant | coolant which the scroll compressor discharged.
For this reason, the liquid refrigerant to be injected can be adjusted in accordance with an increase in the discharge pipe temperature of the low-source compressor 5, and the discharge pipe temperature can be adjusted.
Therefore, the refrigerant temperature discharged from the low-source compressor 5 can be reduced, and the operating range can be expanded.

In the present embodiment, when the refrigeration apparatus is started, the high-side compressor 1 of the high-side refrigerant circuit is operated to circulate the refrigerant, and the temperature of the cascade capacitor 4 of the low-side refrigerant circuit After the temperature becomes equal to or lower than the predetermined temperature, the operation of the low-source side refrigerant circuit is started.
For this reason, there is an effect that it is possible to prevent the high pressure abnormal pressure increase on the low side due to the increase in the condensation load due to the start of the low side compressor 5.

Further, at the end of the spiral protrusion 101a of the fixed scroll 101 and the end of the spiral protrusion 102a of the orbiting scroll 102, for example, PPS (polyphenylene sulfide resin) is used as a material, and a seal member 105 that seals between the compression chambers is provided. Yes.
Therefore, the wear resistance against liquid refrigerant can be increased, and excessive refrigerant injection is possible.

Embodiment 2. FIG.
FIG. 6 is a diagram showing a refrigerant system according to Embodiment 2 of the present invention.
As shown in FIG. 6, the injection circuit 11 of the second embodiment is configured to depressurize a part of the refrigerant flowing out from the cascade condenser 4 and to flow into the compression chamber of the low-side compressor 5. Yes.
Other configurations and operations are the same as those in the first embodiment.
In the present embodiment, the intermediate cooler 6 may not be provided.

  As described above, even when a part of the refrigerant flowing out of the cascade condenser 4 is injected into the low-side compressor 5, the same effect as in the first embodiment can be obtained.

  1 High side compressor, 2 High side condenser, 3 High side main LEV, 4 Cascade condenser, 5 Low side compressor, 6 Intermediate cooler, 7 Low side main LEV, 8 Low side evaporator , 9 LEV for injection, 10 solenoid valve for injection, 11 injection circuit, 100 shell, 101 fixed scroll, 101a spiral projection, 102 swing scroll, 102a spiral projection, 103 frame, 104 Oldham ring, 105 seal member, 106 bush, 107 Thrust plate, 108 Main shaft, 108a Oil hole, 109 Rotor, 110 Stator, 111 Upper part, 112 Electric motor, 113 Oil pump, 114 Subframe, 115 Oil sump, 116 Discharge port, 117 Discharge pipe, 118 Suction pipe, 120 Injection Over DOO, A suction side compression chamber, B suction side compression chamber, C intermediate pressure compression chambers, D intermediate pressure compression chambers, E discharge side compression chamber, F the discharge side compression chamber, G discharge side compression chamber.

Claims (8)

A first refrigerant circuit that sequentially connects the first compressor, the first condenser, the first expansion mechanism, and the first evaporator, and circulates the first refrigerant;
A second compressor, a second condenser, a second expansion mechanism, and a second evaporator are sequentially connected, and a second refrigerant circuit for circulating the second refrigerant is provided.
In the refrigeration apparatus in which the first refrigerant in the first evaporator and the second refrigerant in the second condenser exchange heat,
Carbon dioxide is used as the second refrigerant,
The second compressor is constituted by a scroll compressor ,
The first refrigerant between the first evaporator and the first compressor in the first refrigerant circuit, and the second refrigerant between the second compressor and the second condenser in the second refrigerant circuit. 2 Provide an intercooler to exchange heat with the refrigerant,
The second refrigerant circuit includes
A refrigeration apparatus comprising: an injection circuit that decompresses a part of the second refrigerant that has flowed out of the intermediate cooler and flows into the compression chamber of the scroll compressor . The refrigerating apparatus according to claim 1, wherein a built-in volume ratio of the scroll compressor is set to 2.0 or less. The scroll compressor is
A plurality of compression chambers are formed by combining the spiral protrusions of the fixed scroll and the spiral protrusions of the orbiting scroll that revolves.
The second refrigerant is sucked from the suction side compression chamber formed at the outermost side in the radial direction, and the second refrigerant is compressed by moving to the center side while reducing the volume by the revolving motion of the swing scroll,
Discharging the compressed second refrigerant from a discharge-side compression chamber that opens to a discharge port provided in a central portion of the fixed scroll;
The intermediate pressure compression chamber, which is the compression chamber that does not communicate with either the suction side compression chamber or the discharge side compression chamber, is formed regardless of the revolution angle of the swing scroll. Refrigeration equipment. The scroll compressor is
The intermediate pressure compression chamber and the injection circuit and claim 3 Symbol mounting of the refrigeration apparatus, characterized in that the injection port is provided for communicating. A variable opening mechanism for reducing the pressure of the second refrigerant flowing through the injection circuit;
Of the second refrigerant circuit, in accordance with the operating pressure ratio is the ratio of the high-pressure side pressure on the low pressure side pressure, to any one of claims 1 to 4, characterized in that to set the opening degree of the decompression mechanism The refrigeration apparatus described. A variable opening mechanism for reducing the pressure of the second refrigerant flowing through the injection circuit;
The refrigerating apparatus according to any one of claims 1 to 4 , wherein an opening degree of the decompression mechanism is set according to a temperature of the second refrigerant discharged from the scroll compressor. When starting the refrigeration system,
Operating the first compressor of the first refrigerant circuit to circulate the first refrigerant;
After the temperature of the second condenser of the second refrigerant circuit is equal to or less than a predetermined temperature, according to any one of claim 1 to 6, characterized in that to start the operation of the second refrigerant circuit Refrigeration equipment. The refrigeration apparatus according to any one of claims 1 to 7 , wherein an HFC-based refrigerant not containing chlorine is used as the first refrigerant.

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