Patent Application
20220154988
The present invention relates to a liquid separator, a cooling system and a gas-liquid separation method, which are mainly used in a cooling system and separate a liquid flowing from an evaporator to a compressor.
In a cooling system including an evaporator, a compressor, a condenser and an expansion valve, an accumulator serving as a liquid separator may be installed in front of the suction port of the compressor.
For example, the cooling system shown in Patent Document 1 is provided with an evaporator, a compressor, a condenser, and a decompression expansion valve along the refrigerant flow path. The evaporator absorbs ambient heat by evaporating the liquid-phase refrigerant. The compressor compresses the vapor-phase refrigerant delivered from the evaporator. The condenser releases the heat of the refrigerant whose high pressure is increased by the compressor to condense the vapor-phase refrigerant. The decompression expansion valve decompresses and expands the liquid-phase refrigerant that has been cooled by the condenser.
This cooling system shown in Patent Document 1 is provided with a liquid separator on the upstream side of the compressor that separates the refrigerant after passing through the evaporator into gas and liquid.
This liquid separator has a vertically elongated separation container as a whole. A refrigerant inflow pipe and a vapor-phase refrigerant outflow pipe are installed on top of the separation container. In addition, a liquid-phase refrigerant outflow pipe is installed at the bottom of the separation container.
In this liquid separator, the refrigerant that has flowed into the inside through the refrigerant inflow pipe is centrifugally separated into a liquid-phase refrigerant and vapor-phase refrigerant while rotating in the circumferential direction along the inner wall of the liquid separator of the separation container.
Subsequently, the vapor-phase refrigerant in the separation container is guided to the decompression expansion valve via the upper vapor-phase refrigerant outflow pipe, and the liquid-phase refrigerant in the separation container is guided to the evaporator via the lower liquid-phase refrigerant outflow pipe.
On the other hand, a similar liquid separator is also shown in Patent Document 2.
Similar to Patent Document 1, the liquid separator disclosed in Patent Document 2 has a closed container formed vertically as a whole. At the bottom of this closed container, a first pipe that allows gas-liquid two-phase fluid to flow into the inside of the closed container, a second pipe that discharges the gas in the closed container to the outside, and a third pipe that discharges the liquid in the closed container to the outside are connected.
In the cooling system shown in Patent Documents 1 and 2, the compressor is located above the accumulator, and the liquid-phase refrigerant returns to the accumulator by gravity.
Therefore, the accumulator is long in the vertical direction, and when the compressor is placed on the accumulator, the upper part of the liquid separator becomes heavy and the center of gravity is high. As a result, the liquid separator becomes unstable, and so new technology has been anticipated in order to remedy this point.
This invention was made in view of the above circumstances. Accordingly, the present invention provides a liquid separator, a cooling system and a gas-liquid separation method that enable a compressor to be placed on a closed container.
In order to solve the above problem, the present invention proposes the following means.
A liquid separator according to a first aspect of the present invention includes a closed container having a cylindrical shape in which a refrigerant is stored; a refrigerant inflow pipe that allows the refrigerant to flow into the closed container; and a refrigerant outflow pipe that allows a vapor-phase refrigerant in a space inside the closed container to flow out, with each of the refrigerant inflow pipe and the refrigerant outflow pipe being connected from the upper side of the closed container to the inside thereof, and the closed container being formed in a short cylindrical shape in which the height is smaller relative to the diameter.
A cooling system according to a second aspect of the present invention includes an evaporator that absorbs ambient heat by evaporating a liquid-phase refrigerant, a compressor that compresses a vapor-phase refrigerant, a condenser that releases the heat of the refrigerant that has been pressurized by the compressor and condenses the vapor-phase refrigerant, and a decompression expansion valve that depressurizes and expands the liquid-phase refrigerant cooled by the condenser along a refrigerant path, in which a liquid separator for gas-liquid separation of the refrigerant after passing through the evaporator is provided on the upstream side of the compressor, the liquid separator has a closed container having a cylindrical shape in which a refrigerant is stored; a refrigerant inflow pipe that allows the refrigerant to flow into the closed container; and a refrigerant outflow pipe that allows the refrigerant in a space inside the closed container to flow out, the closed container being formed in a short cylindrical shape in which the height is smaller relative to the diameter.
A gas-liquid separation method according to a third aspect of the present invention comprising connecting a closed container having a cylindrical shape in which the refrigerant is stored, with a refrigerant inflow pipe that allows a refrigerant to flow into and a refrigerant outflow pipe that allows the refrigerant in a space inside the closed container to flow out, and forming the closed container in a short cylindrical shape in which the height is smaller relative to the diameter.
According to the present invention, a liquid separator can be stably held even if a heavy compressor is arranged on the liquid separator.
A liquid separator 10 according to the embodiment of the present invention will be described with reference to
The liquid separator 10 is located on the upstream side of a compressor 3 in a cooling system 1, and is provided for gas-liquid separation of a refrigerant after passing through an evaporator 2, for example.
This cooling system 1 is provided with the evaporator 2, the compressor 3, a condenser 4, and a decompression expansion valve 5 along a refrigerant flow path 1A. The evaporator 2 absorbs ambient heat by evaporating the liquid-phase refrigerant. The compressor compresses the vapor-phase refrigerant. The condenser 4 releases the heat of the refrigerant that has become high pressure by the compressor 3 to condense (or forcibly compress) the vapor-phase refrigerant. The decompression expansion valve 5 expands the liquid-phase refrigerant supplied from the condenser 4.
The liquid separator 10 located on the upstream side of the compressor 3 has a cylindrical closed container 11 in which the refrigerant C is stored. Inside the closed container 11 are provided a refrigerant inflow pipe 12 for flowing in a vapor phase medium or a gas-liquid two-phase refrigerant and a refrigerant outflow pipe 13 that discharges the vapor-phase refrigerant in the closed container 11 to the outside.
The refrigerant inflow pipe 12 and the refrigerant outflow pipe 13 are each installed from the upper surface 11A of the closed container 11 toward the inside of the container 11B. The refrigerant inflow pipe 12 and the refrigerant outflow pipe 13 are arranged at a mutual interval as large as possible in the radial direction (R direction) of the closed container 11.
Further, the closed container 11 of the liquid separator 10 has a height h that is relatively small with respect to a diameter along the R direction, and is configured to have a short cylindrical shape as a whole.
In such a liquid separator 10, since the closed container 11 is formed in a short cylindrical shape, even if a heavy compressor 3 is arranged on the upper surface 11A of the closed container 11, it is possible to hold the liquid separator 10 in a stable state without the upper part of the liquid separator 10 becoming heavy, that is, becoming so-called top heavy.
In such a vapor compression type cooling system 1, the vapor-phase refrigerant that has absorbed heat H1 from the heat source by the evaporator 2 and evaporated is gas-liquid separated by the liquid separator 10, compressed by the compressor 3 and then sent to the condenser 4. Subsequently, the liquid-phase refrigerant, which is condensed by heat dissipation H2 to a cold source in the condenser 4, is depressurized to a predetermined pressure by the decompression expansion valve 5 and sent to the evaporator 2 again.
Here, the liquid-phase refrigerant may not be sufficiently evaporated in the evaporator 2 due to a decrease in the load of the heat source, a failure of the decompression expansion valve 5, and the like and may be supplied to the compressor 3 as a gas-liquid mixed flow. The phenomenon in which a liquid is supplied to the compressor 3 in this way is called a liquid bag. When a liquid is supplied to the compressor 3, the performance of the compressor 3 may be deteriorated or a failure may be caused. In order to prevent this, in the liquid separator 10 according to the embodiment of the present invention, the liquid is separated from the gas-liquid mixed flow after passing through the evaporator 2, and only the gas is supplied to the compressor 3.
As described above, in the liquid separator 10 according to the embodiment of the present invention, the closed container 11 is formed with a short cylindrical shape whose height (h) is relatively small with respect to the radial direction (R direction). Accordingly, the height of the entire cooling system can be lowered, and so even if the heavy compressor 3 is arranged on the upper surface 11A of the closed container 11, the device as a whole can be installed in a stable state without becoming top heavy.
Further, in the liquid separator 10, the closed container 11 is formed in a short cylinder shape. Accordingly, the refrigerant inflow pipe 12 and the refrigerant outflow pipe 13 can be arranged on the upper surface 11A of the closed container 11 at a sufficient interval in the radial direction (R direction).
As a result, in the liquid separator 10, it is possible to prevent the effect of turbulence of the liquid level of the refrigerant caused by inflow of the refrigerant from the refrigerant inflow pipe 12 to the closed container 11 from extending to the refrigerant flowing out to the refrigerant outflow pipe 13. Therefore, it is possible to prevent beforehand the situation of the liquid-phase refrigerant in the closed container 11 flowing out from the refrigerant outflow pipe 13 as a result of being churned.
The liquid separator 200 according to the first embodiment of the present invention will be described with reference to
This liquid separator 200 is installed in the cooling system F.
As shown in
The refrigerant supplied from the decompression expansion valve 500 via the refrigerant flow path 650 absorbs heat H1 from the heat source by the evaporator 100 and evaporates. The evaporated vapor-phase refrigerant passes through the refrigerant flow path 610, the liquid separator 200, and the refrigerant flow path 620 in this order, and is sent to the compressor 300.
The vapor-phase refrigerant compressed to high temperature and high pressure by the compressor 300 is sent to the condenser 400 via the refrigerant flow path 630, radiates H2 to a cold source, and condenses.
After that, the liquid-phase refrigerant condensed in the condenser 400 moves to the decompression expansion valve 500 through the refrigerant flow path 640 and is reduced to a predetermined pressure. Subsequently, the liquid-phase refrigerant is sent to the evaporator 100 again through the refrigerant flow path 650.
Here, the liquid separator 200 is arranged on the upstream side of the compressor 300 and has a role of preventing the liquid-phase refrigerant from being sucked into the compressor 300.
Since the compressor 300 is designed to compress the vapor-phase refrigerant, it is known that if the liquid-phase refrigerant is mixed in, it will lead to a failure (called a liquid-back phenomenon). Normally, the refrigerant completely evaporates in the evaporator 100 and becomes only a vapor-phase refrigerant. However, in the evaporator 100, when a disturbance such as a decrease in heat load occurs, the refrigerant may not evaporate and a part of the liquid-phase refrigerant may remain. In that case, this liquid-phase refrigerant is sent to the refrigerant flow path 610. Therefore, the liquid separator 200 separates the liquid-phase refrigerant contained in the refrigerant and supplies only the vapor-phase refrigerant to the downstream compressor 300.
Unless there are restrictions on installation, it is preferable to construct the refrigerant flow path 620 while avoiding a structure having a reverse gradient with respect to the direction of gravity or a U-shaped structure. This is because if such a reverse gradient structure or U-shaped structure exists in the refrigerant flow path 620, the liquid-phase refrigerant condensed in the refrigerant flow path 620 will accumulate at that portion when the cooling system F is stopped. In this way, since the liquid-phase refrigerant that accumulates in the refrigerant flow path 620 is sucked into the compressor 300 together with the vapor-phase refrigerant when the cooling system F is started next time, despite the fact that the liquid separator 200 is installed, there is a risk of causing the liquid-back phenomenon in the compressor 300.
With reference to
The refrigerant inflow pipe 220 and the refrigerant outflow pipe 230 are installed from the upper surface 210A of the housing 210 toward the inside of the container 210B. The refrigerant inflow pipe 220 and the refrigerant outflow pipe 230 are arranged at an interval in the radial direction (R direction) of the housing 210. The refrigerant inflow pipe 220 is connected to the refrigerant flow path 610 in which the vapor-phase refrigerant or the gas-liquid two-phase refrigerant from the evaporator 100 is guided. The refrigerant outflow pipe 230 is connected to a refrigerant flow path 620 that guides the vapor-phase refrigerant to the compressor 300.
The vapor-phase refrigerant or the gas-liquid two-phase refrigerant after passing through the evaporator 100 flows into the housing 210 through the refrigerant inflow pipe 220, and the liquid-phase refrigerant in the gas-liquid mixed flow falls to the bottom of the housing 210 by gravity and accumulates there. On the other hand, the vapor-phase refrigerant in the gas-liquid mixed flow is sent to the compressor 300 through the refrigerant outflow pipe 230.
The housing 210 of the liquid separator 200 has a height h relatively small with respect to a diameter along the R direction, and is configured to have a short cylindrical shape as a whole.
As described above, in the liquid separator 200, since the housing 210 is formed in the shape of a short cylinder whose height h is relatively small with respect to the diameter in the R direction, even if the compressor 300 with weight is arranged on the upper surface 210A of the housing 210, it is possible to hold the compressor 300 in a stable state.
Referring to
As shown in
In the housing 210, when the flow velocity of the vapor-phase refrigerant C1 supplied through the refrigerant inflow pipe 220 is large, even if the liquid-phase refrigerant is not mixed in the refrigerant C1, the liquid-phase refrigerant C2 staying on the bottom surface of the housing 210 may be blown up by the momentum of the vapor-phase refrigerant C1. In this case, there is a risk that the blown-up liquid-phase refrigerant C2 will flow out from an outlet (opening for the liquid to flow out from the housing 210) 230A of the refrigerant outflow pipe 230.
Therefore, as shown in
As described above, in the liquid separator 200 according to the first embodiment, since the housing 210 is formed in a short cylindrical shape having a height h relatively small in the radial direction (R direction), even if the heavy compressor 300 is arranged on the upper surface 210A of the housing 210, the liquid separator 200 can be held in a stable state without becoming top heavy.
In the liquid separator 200, since the housing 210 is formed in a short cylinder shape, the refrigerant inflow pipe 220 and the refrigerant outflow pipe 230 can be arranged in the upper surface 210A of the housing 210 at a regular interval in the radial direction (R direction).
As a result, in the liquid separator 200, the effect of undulation (turbulence) of the liquid level of the liquid-phase refrigerant C2 caused by the inflow of the refrigerant from the refrigerant inflow pipe 220 into the housing 210 is prevented from extending to the refrigerant outflow pipe 230. Therefore, it is possible to prevent the liquid-phase refrigerant C2 in the housing 210 from being blown up and flowing out from the refrigerant outflow pipe 230.
Further, in the liquid separator 200, providing the mesh-shaped splash prevention plate 240 below the inlet 220A of the refrigerant inflow pipe 220 alleviates the momentum of the vapor-phase refrigerant C1 colliding with the liquid surface to prevent undulation of the liquid level of the liquid-phase refrigerant C2. This also makes it possible to prevent the liquid-phase refrigerant C2 in the housing 210 from flowing out from the outlet 230A of the refrigerant outflow pipe 230.
Further, in the liquid separator 200, there is no complicated structure causing a large pressure loss in the flow path of the vapor-phase refrigerant from the refrigerant inflow pipe 220 to the refrigerant outflow pipe 230. As a result, in the liquid separator 200, it is possible to prevent the so-called liquid back phenomenon to the compressor 300 (damage to the pipeline and equipment of the cooling system due to droplets of the refrigerant flowing through the flow path with kinetic energy) while suppressing the pressure loss during the gas-liquid separation of the refrigerant.
In the above embodiment, a mesh-shaped plate is used as the splash prevention plate 240, but the present invention is not limited thereto. That is, as the splash prevention plate 240, a plate having a large number of through holes 240a as shown in
Further, as the splash prevention plate 240, a net-like body formed by entwining a plurality of fibers 240b as shown in
A liquid separator 200′ according to the second embodiment of the present invention will be described with reference to
The liquid separator 200′ according to the second embodiment differs from the liquid separator 200 according to the first embodiment on the point of a liquid intrusion prevention plate 250 being provided below the outlet of the refrigerant outflow pipe 230.
In the liquid separator 200′ shown in the second embodiment, when the flow velocity of the vapor-phase refrigerant C1 is large, there is a risk of the force blowing up the liquid-phase refrigerant C2 stored in the housing 210 being strong enough such that splash prevention is insufficient with the splash prevention plate 240 alone. Therefore, in the liquid separator 200′, in addition to providing the splash prevention plate 240 below the inlet (outlet when heading toward the liquid separator 200′) 220A of the refrigerant inflow pipe 220, the liquid intrusion prevention plate 250 for preventing suctioning of the liquid-phase refrigerant C2 is provided below the outlet of the refrigerant outflow pipe (the port through which the liquid flows from the liquid separator 200′) 230A.
As a result, in the liquid separator 200′ shown in the second embodiment, by adding the liquid intrusion prevention plate 240 below the refrigerant inflow pipe 220, it is possible to prevent droplets of the liquid-phase refrigerant C2 from being sucked into the refrigerant outflow pipe 230, whereby the liquid separation function can be improved.
As the liquid intrusion prevention plate 240, in addition to a normal plate, it is possible to use a mesh-shaped plate shown in
The liquid separator 200″ according to the third embodiment of the present invention will be described with reference to
The liquid separator 200″ shown in the third embodiment differs from the liquid separators 200 and 200′ shown in the first and second embodiments on the point of being provided with a liquid level sensor 260, a maintenance valve 270, and a control unit 700.
In the normal operation of the cooling system, the gaseous refrigerant is completely sent from the outlet of the evaporator 100, and the liquid-phase refrigerant is transferred from the evaporator 100 to the liquid separator 200 only when the operation becomes unstable due to a disturbance. At this time, due to the unstable operation the liquid-phase refrigerant C2 in the housing 210 gradually evaporates during the subsequent normal operation to become the vapor-phase refrigerant C1, whereby the accumulation thereof is eliminated.
However, if the unstable operation occurs continuously, it is expected that the amount of the liquid-phase refrigerant C2 staying in the housing 210 of the liquid separator 200 will gradually increase.
Therefore, in the liquid separator 200″ shown in the third embodiment, as shown in
If the liquid level of the liquid-phase refrigerant C2 that accumulates in the housing 210 becomes higher than the position of the droplet prevention plate 240, the droplet prevention plate 240 will not function and the liquid separation function may be significantly reduced.
In this case, since the liquid-phase refrigerant C2 may flow out from the refrigerant outflow pipe 230 and cause liquid back, it will be necessary to stop the compressor 300.
Therefore, in the liquid separator 200″ of the third embodiment, as shown in
Then, in the liquid separator 200″ of the third embodiment, after the cooling system F′ is stopped, the maintenance valve 270 at the lower part of the housing 210 is opened and the accumulated liquid-phase refrigerant C2 is discharged, whereby a return to the normal state can be achieved.
The maintenance valve 270 may be opened and closed manually by an operator, or may be opened and closed by a drive means operated by a separately provided control unit 700.
Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range that does not deviate from the gist of the present invention.
Priority is claimed on Japanese Patent Application No. 2019-55600, filed Mar. 22, 2019, the content of which is incorporated herein by reference.
The present invention is mainly used in cooling systems and can be applied to a liquid separator, a cooling system and a gas-liquid separation method that separates liquid flowing from the evaporator into the compressor. Even if a heavy compressor is arranged on top of the liquid separator, the liquid separator can be stably held.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-055600 | Mar 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/009696 | 3/6/2020 | WO | 00 |
