JP7080800B2 - Centrifugal chiller - Google Patents

Description

The present invention relates to a turbo chiller provided with a plurality of compressors, and more particularly to an evaporator in which suction ports of a plurality of compressors are connected.

Centrifugal chillers used in refrigeration and air conditioning equipment are configured as a closed system in which a refrigerant is sealed. Turbo refrigerators are generally an evaporator that takes heat from the fluid to be cooled and the refrigerant evaporates to exert a refrigerating effect, and a compressor that compresses the refrigerant gas evaporated by the evaporator to generate a high-pressure refrigerant gas. A condenser that cools the high-pressure refrigerant gas with a cooling fluid to condense it, and an expansion valve (expansion mechanism) that depressurizes and expands the condensed refrigerant are connected by a refrigerant pipe.

In a turbo chiller equipped with two compressors, it is necessary to equalize the flow rate of the refrigerant gas to each compressor in order to realize stable operation. Therefore, in order to equalize the flow rate, as shown in FIG. 5, two suction pipes 202A and 202B are branched from the common refrigerant gas pipe 201 connected to the evaporator 200, and these two suction pipes 202A and 202B are branched. In some cases, a configuration in which two compressors 205A and 205B are connected to each other is adopted.

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However, in the above configuration using the common refrigerant gas pipe 201, it is necessary to arrange the two compressors 205A and 205B symmetrically. In order to manufacture two symmetrical compressors 205A and 205B, it was necessary to prepare separate molds, which increased the manufacturing cost.

Patent Document 1 discloses a freezing system in which two compressors are arranged so as to face the same direction. According to this arrangement, two compressors having the same shape can be used, so that it is possible to reduce the cost of the compressors. However, since the two compressors are connected to different parts of the evaporator, the flow rates of the refrigerant gas sucked by the two compressors are uneven. That is, since the amount of the refrigerant gas existing in the evaporator usually differs depending on the location in the evaporator, the two compressors suck the refrigerant gas at different flow rates. In order to balance the flow rate of the refrigerant gas in the refrigeration system having such a configuration, complicated control is required.

Therefore, the present invention provides a turbo chiller provided with an evaporator capable of equalizing the flow rate of the refrigerant gas flowing through a plurality of compressors.

In one aspect, an evaporator that evaporates the refrigerant liquid to generate the refrigerant gas, a first compressor and a second compressor that compress the refrigerant gas, and the compressed refrigerant gas are condensed to produce the refrigerant liquid. The first compressor and the second compressor are connected in parallel to the evaporator, and the evaporator includes a can cylinder into which the refrigerant liquid is introduced and the can cylinder. A heat transfer tube arranged inside, an inlet port for introducing a fluid to be cooled into the heat transfer tube, a first refrigerant gas outlet connected to a suction port of the first compressor, and a suction port of the second compressor. The first refrigerant gas outlet is located in the inlet side region of the can cylinder, and the second refrigerant gas outlet is located in the counter-inlet side region of the can cylinder. The inlet side region is adjacent to the inlet port, and assuming that the length in the longitudinal direction of the can body is L, the length of the inlet side region is 1/4 L, and the length of the counter inlet side region is 1/4 L. A turbo refrigerating machine, which is 3/4 L in length, is provided.

In the vicinity of the inlet port, the largest amount of refrigerant gas is generated due to the high temperature of the fluid to be cooled. The present inventor has determined that the ratio of the amount of refrigerant gas present in the 1 / 4L length inlet region to the amount of refrigerant gas present in the 3/4 L length counter-inlet region is 50 :. It was found by experiment and calculation that it became 50. Based on this finding, the first refrigerant gas outlet is located in the inlet side region, and the second refrigerant gas outlet is located in the counter-inlet side region. With such an arrangement, the flow rates of the refrigerant gas flowing through the first compressor and the second compressor can be made uniform. As a result, the first and second compressors can be operated under the same conditions, eliminating the need for complex controls to balance the operation of the first and second compressors. ..

In one aspect, the first refrigerant gas outlet is located on the center side of the inlet side region in the longitudinal direction of the can body .
In one aspect, the second refrigerant gas outlet is located on the center side of the counter-inlet side region in the longitudinal direction of the can body .
According to the present invention, the flow rate of the refrigerant gas flowing into the first compressor can be made equal to the flow rate of the refrigerant gas flowing into the second compressor.

In one aspect, the evaporator further comprises a demister arranged to close the inside of the can body, the demister being located above the heat transfer tube.
According to the present invention, the flow velocity of the refrigerant gas rising in the can body is made uniform by the demista, and a uniform flow of the refrigerant gas can be formed in the can body. As a result, it is possible to secure a uniform flow rate of the refrigerant gas toward the first compressor and the second compressor.

In one aspect, the evaporator has a refrigerant liquid introduction port provided in the can body, and the refrigerant liquid introduction port is a center in the longitudinal direction of the can body and an end wall on the counter-inlet port side. It is located between and.
In one aspect, the refrigerant liquid introduction port is the amount of the refrigerant gas existing in the inlet side region when the refrigerant liquid containing the refrigerant gas is introduced into the can body from the refrigerant liquid introduction port, and the said. The ratio of the amounts of the refrigerant gas existing in the counter-inlet side region is 50:50.
According to the present invention, the flow rates of the refrigerant gas flowing through the first compressor and the second compressor can be accurately equalized.

In one aspect, the turbo chiller further comprises a hot gas bypass line extending from the condenser to the evaporator, the hot gas bypass line being connected to a hot gas inlet provided in the can body. The hot gas inlet is located between the center of the can body in the longitudinal direction and the end wall on the counter-inlet port side.
In one aspect, the hot gas introduction port is located at a position where the ratio of the amount of the refrigerant gas existing in the inlet side region to the amount of the refrigerant gas existing in the counter-inlet side region is 50:50.
According to the present invention, the flow rates of the refrigerant gas flowing through the first compressor and the second compressor can be accurately equalized.

According to the present invention, the flow rates of the refrigerant gas flowing through the first compressor and the second compressor can be made uniform. As a result, the first and second compressors can be operated under the same conditions, eliminating the need for complex controls to balance the operation of the first and second compressors. ..

It is a schematic diagram which shows one Embodiment of a turbo chiller. It is sectional drawing which shows one Embodiment of the evaporator shown in FIG. It is sectional drawing which shows the other embodiment of an evaporator. It is sectional drawing seen from the longitudinal direction of the evaporator shown in FIG. It is a side view which shows the evaporator and the compressor of the conventional turbo chiller.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a turbo chiller. As shown in FIG. 1, the turbo refrigerator includes an evaporator 2 that evaporates a refrigerant liquid to generate a refrigerant gas, a first compressor 1A and a second compressor 1B that compress the refrigerant gas, and a compressed refrigerant. The condenser 3 that condenses the gas to generate the refrigerant liquid, the first compressor 5A and the second compressor 5B that drive the first compressor 1A and the second compressor 1B at variable speeds, respectively, and the first compressor 1A and the first 2 A control device 10 for controlling the operation of the compressor 1B, the first inverter 5A, and the second inverter 5B is provided.

The first compressor 1A and the second compressor 1B are connected in parallel to the evaporator 2. The evaporator 2 has a first refrigerant gas outlet 2A and a second refrigerant gas outlet 2B. The suction port of the first compressor 1A is connected to the first refrigerant gas outlet 2A by the refrigerant pipe 4A, and the suction port of the second compressor 1B is connected to the second refrigerant gas outlet 2B by the refrigerant pipe 4B.

The turbo chiller further comprises an economizer 20 disposed between the condenser 3 and the evaporator 2. The discharge ports of the first compressor 1A and the second compressor 1B are connected to the condenser 3 by the refrigerant pipes 4C and 4D. The condenser 3 is connected to the economizer 20 by the refrigerant pipe 4E, and the economizer 20 is connected to the evaporator 2 by the refrigerant pipe 4F. Further, the economizer 20 is connected to the first compressor 1A by the refrigerant pipe 4G, and is connected to the second compressor 1B by the refrigerant pipe 4H. The economizer 20 is an intercooler arranged between the condenser 3 and the evaporator 2. A primary side expansion valve 21 is attached to the refrigerant pipe 4E extending from the condenser 3 to the economizer 20, and a secondary side expansion valve 22 is attached to the refrigerant pipe 4F extending from the economizer 20 to the economizer 2.

The turbo chiller includes a hot gas bypass line 25 that guides the refrigerant gas from the condenser 3 to the evaporator 2, and a hot gas bypass valve 27 for opening and closing the hot gas bypass line 25. The hot gas bypass line 25 bypasses the economizer 20 and extends from the condenser 3 to the evaporator 2. The hot gas bypass valve 27 is configured so that its opening degree can be adjusted, and is composed of, for example, an electric valve having a variable opening degree.

The hot gas bypass valve 27 is electrically connected to the control device 10, and the operation of the hot gas bypass valve 27 is controlled by the control device 10. In steady operation, the hot gas bypass valve 27 is closed. When the control device 10 opens the hot gas bypass valve 27, the refrigerant gas compressed by the first compressor 1A and the second compressor 1B bypasses the evaporator 20 and passes through the hot gas bypass line 25 from the condenser 3. It is sent to the evaporator 2.

In the present embodiment, the first compressor 1A and the second compressor 1B are composed of a multi-stage turbo compressor. More specifically, the first compressor 1A is composed of a two-stage turbo compressor, and includes a first-stage impeller 11A, a second-stage impeller 12A, and an electric motor 13A for rotating these impellers 11A and 12A. I have. The first inverter 5A is connected to the motor 13A, and the first inverter 5A is connected to the commercial power supply 30. The first inverter 5A is connected to the control device 10. The impellers 11A and 12A are connected to the motor 13A. The electric motor 13A includes an induction motor, and the rotation speed of the electric motor 13A is controlled by the control device 10 via the first inverter 5A.

At the suction port of the first compressor 1A, a first guide vane 16A for adjusting the suction flow rate of the refrigerant gas to the impellers 11A and 12A is arranged. The first guide vane 16A is located on the suction side of the first stage impeller 11A. The first guide vanes 16A are arranged radially, and the opening degree of the first guide vanes 16A is changed by rotating each first guide vane 16A by a predetermined angle in synchronization with each other about its own axis. Will be done. The opening degree of the first guide vane 16A is controlled by the control device 10. The refrigerant gas sent from the evaporator 2 passes through the first guide vanes 16A, and is then sequentially boosted by the rotating impellers 11A and 12A. The boosted refrigerant gas is sent to the condenser 3.

Similar to the first compressor 1A, the second compressor 1B is composed of a two-stage turbo compressor, and is an electric motor that rotates the first-stage impeller 11B, the second-stage impeller 12B, and these impellers 11B and 12B. It includes 13B and a second guide vane 16B arranged at the suction port of the second compressor 1B. The second inverter 5B is connected to the motor 13B, and the second inverter 5B is connected to the commercial power supply 30. The second inverter 5B is connected to the control device 10. Since the configuration and operation of the second compressor 1B not particularly described are the same as the configuration and operation of the first compressor 1A, the duplicate description thereof will be omitted.

The evaporator 2 takes heat from the fluid to be cooled (for example, cold water) and evaporates the refrigerant liquid to exert a freezing effect. The first compressor 1A and the second compressor 1B compress the refrigerant gas evaporated by the evaporator 2 to generate a high-pressure refrigerant gas, and the condenser 3 uses the high-pressure refrigerant gas as a cooling fluid (for example, cooling water). Refrigerant liquid is generated by cooling with and condensing. The refrigerant liquid is depressurized by passing through the primary side expansion valve 21. The refrigerant gas existing in the depressurized refrigerant liquid is separated by the economizer 20, and the intermediate suction port 17A provided between the first stage impeller 11A and the second stage impeller 12A of the first compressor 1A, and the second stage suction port 17A, and the second stage impeller 12A. It is sent to the intermediate suction port 17B provided between the first-stage impeller 11B and the second-stage impeller 12B of the compressor 1B. The refrigerant liquid that has passed through the economizer 20 is depressurized by passing through the secondary expansion valve 22, and is further sent to the evaporator 2 through the refrigerant pipe 4F. In this way, the turbo chiller is configured as a closed system in which the refrigerant is sealed.

The operation of the first inverter 5A and the second inverter 5B is controlled by the control device 10. The control device 10 transmits the same control signal to the first inverter 5A and the second inverter 5B, and operates the first inverter 5A and the second inverter 5B in the same manner. Specifically, the control device 10 rotates the first compressor 1A and the second compressor 1B at the same speed by operating the first inverter 5A and the second inverter 5B in the same manner.

FIG. 2 is a cross-sectional view of the evaporator 2 shown in FIG. The evaporator 2 includes a can body 40 into which a refrigerant liquid is introduced, a heat transfer tube 43 arranged in the can body 40, an inlet port 46 for introducing a fluid to be cooled (for example, cold water) into the heat transfer tube 43, and a heat transfer tube. The outlet port 47 for discharging the fluid to be cooled flowing through 43, the first refrigerant gas outlet 2A connected to the suction port of the first compressor 1A, and the second refrigerant connected to the suction port of the second compressor 1B. It is equipped with a gas outlet 2B. Although not shown, in the present embodiment, the first compressor 1A and the second compressor 1B are arranged on the can body 40 of the evaporator 2.

The evaporator 2 further includes a refrigerant liquid introduction port 51 and a hot gas introduction port 52. The refrigerant liquid introduction port 51 and the hot gas introduction port 52 are located at the lower part of the can body 40. The refrigerant liquid introduction port 51 is connected to the refrigerant pipe 4F shown in FIG. 1, and the hot gas introduction port 52 is connected to the hot gas bypass line 25. The refrigerant liquid generated by the condenser 3 flows into the can body 40 through the refrigerant liquid introduction port 51. In the present embodiment, the refrigerant liquid flows from the condenser 3 to the evaporator 2 via the economizer 20.

One end of the heat transfer tube 43 communicates with the inlet port 46, and the other end of the heat transfer tube 43 communicates with the outlet port 47. The heat transfer tube 43 extends over the entire length of the can body 40 and is folded back. Therefore, in the present embodiment, the inlet port 46 and the outlet port 47 are arranged on the same side of the can body 40. In FIG. 2, the heat transfer tube 43 is schematically drawn. In one embodiment, the heat transfer tube 43 may or may not be folded back multiple times. The exit port 47 may be arranged on the opposite side of the can body 40 when viewed from the inlet port 46.

The first refrigerant gas outlet 2A is located in the inlet side region 40A of the can body 40, and the second refrigerant gas outlet 2B is located in the counter-inlet side region 40B of the can body 40. The inlet side region 40A is a region located on the inlet side of the can cylinder 40, and the counter-entrance side region 40B is a region located on the counter-entrance side of the can cylinder 40. That is, the inlet side region 40A is adjacent to the inlet port 46, and the anti-entrance side region 40B is located on the opposite side of the can body 40 with the inlet side region 40A interposed therebetween. The inlet side region 40A is located between the inlet port 46 and the counter-entrance side region 40B. Assuming that the length of the can body 40 in the longitudinal direction is L, the length of the inlet side region 40A is 1 / 4L, and the length of the counter-entrance side region 40B is 3/4 L.

The first refrigerant gas outlet 2A is located at the top of the inlet side region 40A, and the second refrigerant gas outlet 2B is located at the top of the counter-inlet side region 40B. In the present embodiment, the first refrigerant gas outlet 2A is located on the center side of the inlet side region 40A, and the second refrigerant gas outlet 2B is located on the center side of the counter-inlet side region 40B. The refrigerant liquid introduction port 51 and the hot gas introduction port 52 are located in the counter-inlet side region 40B.

The refrigerant liquid is introduced into the can body 40 from the refrigerant liquid introduction port 51. The fluid to be cooled flows into the heat transfer tube 43 from the inlet port 46, flows through the heat transfer tube 43, and flows out from the outlet port 47. The heat of the fluid to be cooled flowing in the heat transfer tube 43 is transferred to the refrigerant liquid in the can body 40. The refrigerant liquid evaporates to become a refrigerant gas, while the fluid to be cooled is cooled by the refrigerant liquid. Since the fluid to be cooled flows into the can body 40 from the inlet port 46, the refrigerant liquid evaporates more violently in the inlet side region 40A near the inlet port 46, and a large amount of refrigerant gas is generated. On the other hand, in the non-inlet side region 40B away from the inlet port 46, a smaller amount of refrigerant gas is generated than in the inlet side region 40A.

In the vicinity of the inlet port 46, the largest amount of refrigerant gas is generated due to the high temperature of the fluid to be cooled. The present inventor has determined that the ratio of the amount of refrigerant gas present in the 1 / 4L length inlet side region 40A to the amount of refrigerant gas present in the 3/4L length counter-inlet side region 40B is. It was found by experiment and calculation that it was 50:50. Based on this finding, the first refrigerant gas outlet 2A is located in the inlet side region 40A, and the second refrigerant gas outlet 2B is located in the counter-inlet side region 40B. With such an arrangement, the flow rates of the refrigerant gas flowing through the first compressor 1A and the second compressor 1B can be made uniform. As a result, the first compressor 1A and the second compressor 1B can be operated under the same conditions without the need for complicated control for balancing the operation of the first compressor 1A and the second compressor 1B. can do.

In particular, according to the present embodiment, the first refrigerant gas outlet 2A is located on the center side of the inlet side region 40A which is a strong boiling region, and the second refrigerant gas outlet 2B is a counter-inlet which is a weak boiling region. Since it is located on the center side of the side region 40B, the flow rate of the refrigerant gas flowing into the first compressor 1A can be made equal to the flow rate of the refrigerant gas flowing into the second compressor 1B. From the viewpoint of equalizing the flow rates of the refrigerant gas flowing into the first compressor 1A and the second compressor 1B, the first refrigerant gas outlet 2A is preferably located on the center of the inlet side region 40A, and the second refrigerant gas outlet 2B is preferable. Is preferably on the center of the counter-entrance side region 40B.

The refrigerant liquid introduction port 51 is located between the center of the can body 40 in the longitudinal direction and the end wall 41 on the counter-inlet port side of the can body 40. The end wall 41 on the counter-entrance port side is located on the opposite side of the inlet port 46. The refrigerant liquid flowing into the evaporator 2 is usually accompanied by bubbles composed of the refrigerant gas. The bubbles contained in this refrigerant liquid are supplied to the counter-inlet side region 40B and mixed with the refrigerant gas generated in the evaporator 2. Therefore, the position of the refrigerant liquid introduction port 51 affects the ratio of the amount of the refrigerant gas existing in the inlet side region 40A and the amount of the refrigerant gas existing in the counter-inlet side region 40B.

In the present embodiment, the bubbles contained in the refrigerant liquid are supplied to the counter-inlet side region 40B, which is a weak boiling region, so that the amount of the refrigerant gas in the entire can body 40 is balanced. In particular, the refrigerant liquid introduction port 51 includes the amount of the refrigerant gas existing in the inlet side region 40A when the refrigerant liquid containing bubbles composed of the refrigerant gas is introduced into the can body 40 from the refrigerant liquid introduction port 51. The ratio of the amounts of the refrigerant gas existing in the counter-inlet side region 40B is 50:50. According to this embodiment, the flow rates of the refrigerant gas flowing through the first compressor 1A and the second compressor 1B can be accurately equalized.

The hot gas introduction port 52 is located between the center of the can body 40 in the longitudinal direction and the end wall 41 on the counter-inlet port side. More specifically, the hot gas introduction port 52 is located between the refrigerant liquid introduction port 51 and the end wall 41 on the counter-inlet port side. The hot gas bypass valve 27 is opened when the refrigerating load is low, and the refrigerant gas is supplied from the condenser 3 to the evaporator 2. The refrigerant gas is supplied to the counter-inlet side region 40B and mixed with the refrigerant gas generated in the evaporator 2. Therefore, the position of the hot gas introduction port 52 also affects the ratio of the amount of the refrigerant gas existing in the inlet side region 40A to the amount of the refrigerant gas existing in the counter-inlet side region 40B.

In the present embodiment, the refrigerant gas is supplied to the counter-inlet side region 40B, which is a weak boiling region, so that the amount of the refrigerant gas in the entire can body 40 is balanced. In particular, the hot gas introduction port 52 has the amount of the refrigerant gas existing in the inlet side region 40A and the inside of the counter-inlet side region 40B when the refrigerant gas is introduced into the can body 40 from the hot gas introduction port 52. The ratio of the amount of refrigerant gas present in is 50:50. According to this embodiment, the flow rates of the refrigerant gas flowing through the first compressor 1A and the second compressor 1B can be accurately equalized.

FIG. 3 is a cross-sectional view showing another embodiment of the evaporator 2, and FIG. 4 is a cross-sectional view of the evaporator 2 shown in FIG. 3 as viewed from the longitudinal direction thereof. Since the configuration of the present embodiment, which is not particularly described, is the same as that of the embodiment shown in FIG. 2, the duplicated description thereof will be omitted. In the present embodiment, the evaporator 2 further includes a demista 60 arranged so as to close the inside of the can body 40. The demista 60 is located above the heat transfer tube 43 and covers the entire heat transfer tube 43. The demista 60 extends from one end to the other end inside the can body 40.

The demista 60 is a porous member made of a mesh or the like that allows the passage of the refrigerant gas. The demista 60 is located above the heat transfer tube 43 and below the first refrigerant gas outlet 2A and the second refrigerant gas outlet 2B.

The refrigerant gas existing in the can body 40 flows upward, passes through the demista 60, and flows into the first refrigerant gas outlet 2A and the second refrigerant gas outlet 2B. When the refrigerant gas passes through the demista 60, the flow velocity of the refrigerant gas is made uniform. As a result, it is possible to secure a uniform flow rate of the refrigerant gas toward the first compressor 1A and the second compressor 1B.

The above-described embodiments have been described for the purpose of allowing a person having ordinary knowledge in the technical field to which the present invention belongs to carry out the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the invention is not limited to the described embodiments, but is to be construed in the broadest range according to the technical ideas defined by the claims.

1A 1st compressor 1B 2nd compressor 2 Evaporator 2A 1st refrigerant gas outlet 2B 2nd refrigerant gas outlet 3 Condenser 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H Refrigerant piping 5A 1st inverter 5B 2nd Inverter 10 Controller 11A, 11B 1st Stage Impeller 12A, 12B 2nd Stage Impeller 13A, 13B Electric Motor 16A 1st Guide Vane 16B 2nd Guide Vane 20 Economizer 21 Primary Side Expansion Valve 22 Secondary Side Expansion Valve 25 Hot Gas bypass line 27 Hot gas bypass valve 30 Commercial power supply 40 Can body 40A Inlet side area 40B Anti-inlet side area 41 End wall 43 Heat transfer tube 46 Inlet port 47 Outlet port 51 Refrigerant liquid introduction port 52 Hot gas introduction port 60 Demista

Claims (4)

An evaporator that evaporates the refrigerant liquid to generate refrigerant gas,
The first compressor and the second compressor that compress the refrigerant gas,
A condenser that condenses the compressed refrigerant gas to generate the refrigerant liquid is provided.
The first compressor and the second compressor are connected in parallel to the evaporator.
The evaporator includes a can body into which the refrigerant liquid is introduced, a heat transfer tube arranged in the can body, an inlet port for introducing a cooled fluid into the heat transfer tube, and a suction port of the first compressor. A first refrigerant gas outlet connected to the second compressor and a second refrigerant gas outlet connected to the suction port of the second compressor are provided.
The first refrigerant gas outlet is located in the inlet side region of the can body.
The second refrigerant gas outlet is located in the counter-inlet side region of the can body.
The inlet side area is adjacent to the inlet port and
Assuming that the length of the can body in the longitudinal direction is L, the length of the inlet side region is 1 / 4L, and the length of the counter-entrance side region is 3/4 L.
The first refrigerant gas outlet is located on the center side of the inlet side region in the longitudinal direction of the can body.
The second refrigerant gas outlet is a turbo chiller located on the center side of the counter-inlet side region in the longitudinal direction of the can body . The turbo chiller according to claim 1 , wherein the evaporator further includes a demister arranged so as to close the inside of the can body, and the demister is located above the heat transfer tube. The evaporator has a refrigerant liquid introduction port provided in the can body, and has a refrigerant liquid introduction port.
The turbo chiller according to claim 1, wherein the refrigerant liquid introduction port is located between the center in the longitudinal direction of the can body and the end wall on the counter-inlet port side. An evaporator that evaporates the refrigerant liquid to generate refrigerant gas,
The first compressor and the second compressor that compress the refrigerant gas,
A condenser that condenses the compressed refrigerant gas to generate the refrigerant liquid, and
With a hot gas bypass line extending from the condenser to the evaporator
The first compressor and the second compressor are connected in parallel to the evaporator.
The evaporator includes a can body into which the refrigerant liquid is introduced, a heat transfer tube arranged in the can body, an inlet port for introducing a cooled fluid into the heat transfer tube, and a suction port of the first compressor. A first refrigerant gas outlet connected to the second compressor and a second refrigerant gas outlet connected to the suction port of the second compressor are provided.
The first refrigerant gas outlet is located in the inlet side region of the can body.
The second refrigerant gas outlet is located in the counter-inlet side region of the can body.
The inlet side area is adjacent to the inlet port and
Assuming that the length of the can body in the longitudinal direction is L, the length of the inlet side region is 1 / 4L, and the length of the counter-entrance side region is 3/4 L.
The hot gas bypass line is connected to a hot gas introduction port provided in the can body.
The hot gas inlet is a turbo chiller located between the center in the longitudinal direction of the can body and the end wall on the counter-inlet port side.

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