JP6716227B2 - Evaporator, turbo refrigerator equipped with the same - Google Patents

Description

The present invention relates to an evaporator that evaporates a low-pressure refrigerant, and a turbo refrigeration system including the evaporator.

For example, as is well known, a turbo refrigeration system used as a heat source for district cooling and heating includes a turbo compressor that compresses a refrigerant, a condenser that condenses the compressed refrigerant, and a control valve that expands the condensed refrigerant. And an intercooler that separates the expanded refrigerant into a gas and a liquid, and an evaporator that evaporates the expanded refrigerant.

As disclosed in Patent Document 1, the evaporator includes a cylindrical shell-shaped pressure vessel, and a heat transfer tube through which a liquid to be cooled such as water passes so as to penetrate the pressure vessel in the longitudinal axis direction. A group is arranged. Further, inside the pressure vessel, a distribution plate (refrigerant distribution plate) having a large number of refrigerant circulation holes formed below the heat transfer tube group is provided, and an eliminator (demister) is provided above the heat transfer tube group. There is.

The liquid-phase refrigerant compressed by the turbo compressor and condensed by the condenser flows into the pressure vessel through the refrigerant inlet provided at the lower portion of the pressure vessel, and passes through many refrigerant circulation holes of the distribution plate. As a result, heat is exchanged with the heat transfer tube group while diffusing all over the pressure vessel. As a result, the liquid to be cooled flowing inside the heat transfer tube group is cooled, and the cooled liquid to be cooled is used as a cooling/heating medium for air conditioning or an industrial cooling liquid.

The liquid-phase refrigerant that has exchanged heat with the heat transfer tube group boils and vaporizes due to the temperature difference. Then, the liquid phase component is removed when passing through the eliminator, and only the vapor phase refrigerant is sucked into the turbo compressor through the suction pipe connected to the upper portion of the pressure vessel and compressed again.

In the conventional evaporator, the inner diameter of the refrigerant flow hole in the distribution plate, the perforation interval, and the like are constant. That is, the area ratio of the refrigerant circulation holes per unit area of the distribution plate was constant throughout the distribution plate.

Further, the eliminator was arranged at a position sufficiently higher than the liquid level of the refrigerant in the pressure vessel. The reason for this is to prevent so-called carryover (entrainment of gas and liquid), in which liquid droplets of the boiling refrigerant pass through the eliminator and enter the suction pipe in the liquid phase, and suppress the efficiency reduction of the turbo compressor. Is.

JP 61-280359A

A low-pressure refrigerant such as R1233zd used at a maximum pressure of less than 0.2 MPaG is expected as a next-generation refrigerant because it can enhance the efficiency of the turbo refrigeration system and has a low global warming potential.

Since such a low-pressure refrigerant has a characteristic that the specific volume of gas is larger than that of a high-pressure refrigerant such as R134a, a boiling bubble becomes large when it boils by exchanging heat with the heat transfer tube group inside the evaporator. Therefore, the heat transfer tube group is locally surrounded by boiling bubbles, so-called dryout is likely to occur, and the heat transfer performance tends to be lower than that in the state where the heat transfer tube group is immersed in the refrigerant two-phase liquid. ..

Further, in the upstream part of the heat transfer tube group inside the evaporator, the temperature of the liquid to be cooled flowing in the heat transfer tube group and the refrigerant is large, so that the refrigerant boils violently, but in the downstream part of the heat transfer tube group, the above temperature difference. Is reduced, the boiling of the refrigerant becomes moderate. Therefore, it becomes difficult to set or adjust the liquid level (floss level) of the liquid-phase refrigerant pool inside the evaporator.

Furthermore, since the gap flow velocity is high in the heat transfer tube group, there is a fear of fatigue fracture due to the drag force applied to each heat transfer tube. When a low-pressure refrigerant is used, since the volumetric flow rate of the vaporized refrigerant sucked from the evaporator to the turbo compressor is significantly larger than that of the high-pressure refrigerant, the flow rate of the vaporized refrigerant inside the evaporator is high, and the vaporized refrigerant is The liquid-phase refrigerant is liable to carry over to the turbo compressor side due to the above flow, and the efficiency of the turbo compressor may be reduced.

The present invention has been made in view of such circumstances, and in a turbo refrigerating apparatus using a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG, prevents dry-out of a heat transfer tube group in an evaporator. It is an object of the present invention to provide an evaporator capable of enhancing heat transfer performance and suppressing a decrease in efficiency due to carryover of a liquid phase low-pressure refrigerant to the turbo compressor side, and a turbo refrigeration system including the evaporator. And

In order to solve the above problems, the present invention employs the following means.
The evaporator according to the first aspect of the present invention is provided in a lower portion of the pressure vessel, which extends in a horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced. The refrigerant inlet, the refrigerant outlet provided in the upper part of the pressure vessel, and the inside of the pressure vessel in the longitudinal axis direction, the liquid to be cooled is circulated therein, and the liquid to be cooled and the low pressure refrigerant and heat. and the heat transfer tube group to be replaced, is placed in the interior of the pressure vessel between the heat transfer tube group and the coolant inlet, comprising a plate-shaped refrigerant distribution plate refrigerant flow hole is bored, wherein the heat transfer The heat pipe group communicates with the outward pipe group extending from one end to the other end in the longitudinal direction inside the pressure vessel and the other end in the longitudinal axis direction inside the pressure container, and communicates with the outward pipe group in the longitudinal axis direction inside the pressure container. A return pipe group returning from the other end to one end, wherein the heat transfer tube group is supported by a flat heat transfer tube support plate having a surface direction intersecting the longitudinal axis direction of the pressure vessel, and is a unit in the refrigerant distribution plate. The area ratio of the refrigerant flow holes per area is made larger than other ranges in a range corresponding to the upstream side positions of the forward path tube group and the return path tube group, and corresponds to the vicinity of the refrigerant outlet. It is characterized in that it is smaller than the other ranges in the range .

As described above, the area ratio of the refrigerant circulation holes per unit area in the refrigerant distribution plate is larger than the other ranges in the range corresponding to the vicinity of the position on the upstream side of the heat transfer tube group, and thus from the refrigerant inlet to the pressure vessel. A large amount of the introduced low-pressure refrigerant is distributed near the position on the upstream side of the heat transfer tube group. Further, a relatively small amount of low pressure refrigerant is distributed to other positions. As a result, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel is made uniform.

In the vicinity of the upstream side of the heat transfer tube group inside the evaporator, the low-pressure refrigerant boils violently because of a large temperature difference with the liquid to be cooled flowing inside the heat transfer tube group. However, since a relatively large amount of low-pressure refrigerant is distributed to this position as compared to other positions, there is no situation in which the vicinity of the upstream side of the heat transfer tube group is surrounded by boiling bubbles of low-pressure refrigerant and dried out. The heat transfer tube group can be kept immersed in the refrigerant two-phase liquid. Therefore, the liquid to be cooled and the low-pressure refrigerant flowing inside the heat transfer tube group can be favorably heat-exchanged, and the heat transfer performance of the heat transfer tube group can be enhanced.

In addition, since the froth level of the low-pressure refrigerant pool does not rise higher than both ends in the longitudinal axis direction at the middle portion in the longitudinal axis direction of the pressure vessel, the refrigerant communicating with the suction pipe of the turbo compressor at the middle portion in the longitudinal axis direction of the pressure vessel. By providing the outlet, it is possible to prevent the liquid-phase low-pressure refrigerant from being carried over to the turbo compressor side along with the flow of the vaporized refrigerant, and to suppress the efficiency reduction of the turbo compressor.

In the above-mentioned evaporator, the refrigerant inlet is provided at an intermediate portion in the longitudinal axis direction of the pressure vessel, and the area ratio of the refrigerant circulation holes in the refrigerant distribution plate is a range of longitudinal end portions of the refrigerant distribution plate. In, the structure may be larger than the range of the intermediate portion in the longitudinal axis direction.

According to the evaporator having the above-mentioned configuration, the low-pressure refrigerant introduced into the pressure vessel from the refrigerant inlet provided at the longitudinal axis direction intermediate portion of the pressure vessel is supplied to both ends of the pressure vessel in the longitudinal axis direction, and the refrigerant. A relatively small amount is supplied to the intermediate portion in the longitudinal axis direction of the pressure vessel, which is immediately above the inlet. For this reason, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel is made uniform, and the liquid to be cooled flowing inside the heat-transfer tube group and the low-pressure refrigerant are satisfactorily heat-exchanged, and the heat transfer of the heat-transfer tube group is performed. Performance can be improved.

The evaporator according to the second aspect of the present invention is provided in a lower portion of the pressure vessel, which extends in the horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced. The refrigerant inlet, the refrigerant outlet provided in the upper part of the pressure vessel, and the inside of the pressure vessel in the longitudinal axis direction, the liquid to be cooled is circulated therein, and the liquid to be cooled and the low pressure refrigerant and heat. A group of heat transfer tubes to be exchanged, a plate-like refrigerant distribution plate installed between the refrigerant inlet and the group of heat transfer tubes inside the pressure vessel, and having a refrigerant flow hole formed therein; A plurality of inlets are provided dispersed along the longitudinal direction of the pressure vessel.

Since the low-pressure refrigerant has a larger specific volume than the high-pressure refrigerant, the volumetric flow rate flowing from the refrigerant inlet into the evaporator is large and the dynamic pressure is high, but if the pressure loss of the refrigerant distribution plate is increased accordingly, the low-pressure refrigerant becomes the refrigerant. The speed of ejection from the refrigerant flow holes of the distribution plate increases, leading to vibration and damage to the heat transfer tube group.

According to the evaporator having the above-described configuration, since the refrigerant inlets are provided in a distributed manner along the longitudinal axis direction of the pressure vessel, the inflow speed of the low-pressure refrigerant is reduced as compared with the case where the refrigerant inlet is single. be able to. Therefore, it is possible to increase the diameter of the refrigerant flow hole of the refrigerant distribution plate, thereby reducing the speed at which the low-pressure refrigerant is ejected from the refrigerant flow hole, and preventing vibration and damage of the heat transfer tube group.

Further, the low-pressure refrigerant can be made to flow evenly from the plurality of refrigerant inlets over the entire length in the longitudinal direction of the pressure vessel to make the floss level of the low-pressure refrigerant pool inside the pressure vessel uniform. As a result, the heat transfer performance is improved by preventing the dry-out of the heat transfer tube group, and the carry-over to the turbo compressor side is suppressed by suppressing the liquid phase low pressure refrigerant from locally spurting up. It is possible to avoid a decrease in the efficiency of the compressor.

An evaporator according to a third aspect of the present invention is provided in a lower portion of the pressure vessel, which extends in a horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced. The refrigerant inlet, the refrigerant outlet provided in the upper part of the pressure vessel, and the inside of the pressure vessel in the longitudinal axis direction, the liquid to be cooled is circulated therein, and the liquid to be cooled and the low pressure refrigerant and heat. A group of heat transfer tubes to be exchanged, a plate-like refrigerant distribution plate installed between the refrigerant inlet and the group of heat transfer tubes inside the pressure vessel, and having a refrigerant flow hole formed therein; It is characterized in that a flow passage cross-sectional area from the outer opening of the inlet to the pressure vessel is enlarged toward the pressure vessel from the outer opening.

According to the evaporator having the above structure, the flow passage cross-sectional area from the outer opening of the refrigerant inlet to the pressure vessel increases toward the pressure vessel, so that the flow velocity of the low-pressure refrigerant flowing through the refrigerant inlet decreases toward the pressure vessel. ..
Therefore, the low-pressure refrigerant is discharged from the refrigerant distribution holes of the refrigerant distribution plate at a reduced speed to prevent vibration and damage of the heat transfer tube group, and the liquid-phase low-pressure refrigerant is locally blown up to perform turbo compression. Carryover to the machine side can be suppressed, and a decrease in the efficiency of the turbo compressor can be avoided.

The evaporator according to the fourth aspect of the present invention is provided in a lower portion of the pressure vessel, which extends in the horizontal direction and into which a low pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced. The refrigerant inlet, the refrigerant outlet provided in the upper part of the pressure vessel, and the inside of the pressure vessel in the longitudinal axis direction, the liquid to be cooled is circulated therein, and the liquid to be cooled and the low pressure refrigerant and heat. A group of heat transfer tubes to be exchanged, a plate-like refrigerant distribution plate installed between the refrigerant inlet and the group of heat transfer tubes inside the pressure vessel, and having a refrigerant flow hole formed therein; The inlet is tubular connected to the pressure vessel, and a flow velocity damping member for damping the flow velocity of the low-pressure refrigerant is provided in the pipe.

According to the evaporator configured as described above, the flow velocity damping member reduces the flow velocity of the low-pressure refrigerant flowing from the coolant inlet into the pressure vessel.
Therefore, the low-pressure refrigerant is discharged from the refrigerant distribution holes of the refrigerant distribution plate at a reduced speed to prevent vibration and damage of the heat transfer tube group, and the liquid-phase low-pressure refrigerant is locally blown up to perform turbo compression. Carryover to the machine side can be suppressed, and a decrease in the efficiency of the turbo compressor can be avoided.

In any of the above evaporators, the heat transfer tube group includes a forward path tube group extending from one end to the other end in the longitudinal direction inside the pressure vessel, and a forward path tube group at the other end in the longitudinal axis direction inside the pressure vessel. A return pipe group which communicates with each other and returns from the other end in the longitudinal direction of the pressure vessel to the one end thereof, wherein the forward pipe group is arranged below and the return pipe group is arranged above inside the pressure container. The configuration may be changed.

According to the evaporator configured as described above, the forward pipe group in which the temperature difference between the liquid to be cooled flowing in the heat transfer tube is large and boiling of the low-pressure refrigerant is intense is arranged at the lower part of the pressure vessel, and the temperature difference between the liquid to be cooled is A small return pipe group, in which the boiling of the low-pressure refrigerant is moderate, is arranged at the upper part of the pressure vessel.
Therefore, the low-pressure refrigerant is vigorously boiled below the liquid surface of the low-pressure refrigerant pool in the pressure vessel, and the liquid-phase refrigerant is less likely to scatter on the liquid surface of the low-pressure refrigerant pool. Therefore, it is possible to prevent the liquid-phase refrigerant from being carried over to the turbo compressor side along with the flow of the vaporized refrigerant, and to suppress the efficiency reduction of the turbo compressor.

In any of the above evaporators, the heat transfer tube group has a configuration in which a plurality of heat transfer tube bundles in which a plurality of heat transfer tubes are bundled are arranged in a horizontal direction, and a gap that extends vertically is formed between the heat transfer tube bundles. Good.

According to the evaporator configured as described above, the vertical gap between the plurality of heat transfer tube bundles serves as a path for boiling bubbles of the low-pressure refrigerant that has boiled by exchanging heat with the heat transfer tube group. Thereby, the boiling bubbles can easily float on the liquid surface of the low-pressure refrigerant. Therefore, it is possible to prevent the heat transfer tube group from being surrounded by the boiling bubbles and being dried out below the liquid surface of the refrigerant, and to improve the heat transfer performance of the heat transfer tube group.

In the above-mentioned evaporator, the refrigerant circulation hole formed in the refrigerant distribution plate may be arranged vertically below the gap.

According to the evaporator having the above configuration, the flow of the low-pressure refrigerant discharged upward through the refrigerant circulation holes formed in the refrigerant distribution plate passes through the gap and reaches the upper end of the heat transfer tube group. The heat transfer performance of the heat pipe group can be improved.

In any of the above evaporators, a demister that is located between the refrigerant outlet and the heat transfer tube group inside the pressure vessel and performs gas-liquid separation of the refrigerant is arranged directly above the heat transfer tube group. The configuration may be changed.

When a low-pressure refrigerant is used, since the gas flow velocity is high, the distance until the jetted droplets of the liquid-phase refrigerant are separated from the vapor-phase refrigerant by its own weight becomes relatively long. Therefore, if the demister is installed at a position higher than the position where the droplets are separated by their own weight, the distance from the liquid surface of the refrigerant to the demister becomes long and the shell diameter of the pressure vessel becomes large.

By disposing the demister just above the heat transfer tube group as described above, it is possible to reduce the amount of droplets to be jetted by the demister and reduce the carryover amount. Furthermore, by disposing the demister directly above the heat transfer tube group, the evaporation mist of the low-pressure refrigerant in the space above the demister is promoted to become droplets of a large diameter, and the distance at which the droplets are separated by their own weight is reduced. Carry over of the refrigerant can be prevented.

In the above evaporator, the demister may be provided such that the entire circumference thereof is in contact with the inner circumference of the pressure vessel.

According to the evaporator having the above structure, the entire amount of the gas flow of the low-pressure refrigerant inside the pressure container must pass through the demister, which increases the flow resistance of the gas flow. Therefore, the flow velocity distribution of the gas flow in the pressure vessel is leveled, the peak value of the local gas flow velocity is reduced, the amount of droplets generated is reduced, and the self-weight separation distance of droplets is shortened. Carry over of the refrigerant can be prevented.

In any of the above evaporators, the individual heat transfer tubes forming the heat transfer tube group have a surface direction intersecting the longitudinal axis direction of the pressure vessel and are spaced apart in the longitudinal axis direction of the pressure vessel. Installed by penetrating through the plurality of heat transfer tube support plates arranged, the installation interval of the heat transfer tube support plate in the vicinity of the upstream side position of the heat transfer tube group is greater than the installation interval of the heat transfer tube support plate at other positions. May be made smaller.

Near the position on the upstream side of the heat transfer tube group, the low-pressure refrigerant boiled violently because the temperature difference between the liquid to be cooled and the low-pressure refrigerant flowing inside the heat transfer tube group was large, and the specific volume of the boiling bubbles was higher than that of the high-pressure refrigerant. Because it is large, it produces more vibration than when a high pressure refrigerant is used. Therefore, there is a concern that the heat transfer tube group may be damaged by resonating with the vibration of the boiling bubbles.

As described above, by setting the installation interval of the heat transfer tube support plate in the vicinity of the upstream side position of the heat transfer tube group to be smaller than the installation interval of the heat transfer tube support plate in other positions, in the vicinity of the upstream side of the heat transfer tube group. Resonance can be suppressed and damage can be prevented.

A turbo refrigerator according to the present invention includes a turbo compressor that compresses a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG, a condenser that condenses the compressed low-pressure refrigerant, and an evaporator that expands the low-pressure refrigerant. It is characterized by comprising any one of the above-mentioned evaporators.

According to the turbo refrigerating apparatus having the above configuration, when a low-pressure refrigerant is used, dry-out of the heat transfer tube group due to boiling bubbles of the low-pressure refrigerant in the evaporator and droplets of the low-pressure refrigerant are carried over to the turbo compressor. This can be prevented and the efficiency can be improved by the low pressure refrigerant.

As described above, according to the evaporator and the turbo refrigerating apparatus including the same of the present invention, in the turbo refrigerating apparatus using the low pressure refrigerant used at the maximum pressure of less than 0.2 MPaG, the heat transfer tube group in the evaporator is provided. It is possible to prevent the dry-out and improve the heat transfer performance, and to suppress a decrease in efficiency due to carryover of the liquid-phase low-pressure refrigerant to the turbo compressor side.

1 is an overall view of a turbo refrigerating device according to an embodiment of the present invention. It is a side view of the evaporator which shows 1st Embodiment of this invention by the II arrow of FIG. FIG. 3 is a vertical sectional view of the evaporator taken along the line III-III in FIG. 2. FIG. 4 is a vertical sectional view of the evaporator taken along line IV-IV in FIG. 2. It is a side view of an evaporator showing a 2nd embodiment of the present invention. It is a longitudinal section of an evaporator showing a 3rd embodiment of the present invention. It is a VII arrow line view of FIG. (A), (b) is a longitudinal section of a refrigerant inlet showing a 4th embodiment of the present invention, respectively.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall view of a turbo refrigeration system according to an embodiment of the present invention. The turbo refrigeration system 1 includes a turbo compressor 2 that compresses a refrigerant, a condenser 3, a high pressure expansion valve 4, an intercooler 5, a low pressure expansion valve 6, an evaporator 7, and a lubricating oil tank 8. The circuit box 9, the inverter unit 10, the operation panel 11 and the like are provided to form a unit. The lubricating oil tank 8 is a tank that stores lubricating oil to be supplied to the bearings, the speed increaser, and the like of the turbo compressor 2.

The condenser 3 and the evaporator 7 are formed in a cylindrical shell shape having high pressure resistance, and are arranged in parallel so as to be adjacent to each other with their axes extending in a substantially horizontal direction. The condenser 3 is arranged at a position relatively higher than the evaporator 7, and a circuit box 9 is installed below the condenser 3. The intercooler 5 and the lubricating oil tank 8 are installed so as to be sandwiched between the condenser 3 and the evaporator 7. The inverter unit 10 is installed above the condenser 3, and the operation panel 11 is arranged above the evaporator 7. The lubricating oil tank 8, the circuit box 9, the inverter unit 10, and the operation panel 11 are arranged so as not to largely protrude from the overall contour of the turbo refrigeration system 1 in a plan view.

The turbo compressor 2 is of a known centrifugal turbine type that is rotationally driven by an electric motor 13, and is arranged above the evaporator 7 in a posture in which its axis extends in a substantially horizontal direction. The electric motor 13 is driven by the inverter unit 10. The turbo compressor 2 compresses the vapor-phase refrigerant supplied from the refrigerant outlet 23 of the evaporator 7 through the suction pipe 14 as described later. As the refrigerant, a low pressure refrigerant such as R1233zd used at a maximum pressure of less than 0.2 MPaG is used.

The discharge port of the turbo compressor 2 and the upper part of the condenser 3 are connected by a discharge pipe 15, and the bottom part of the condenser 3 and the bottom part of the intercooler 5 are connected by a refrigerant pipe 16. A refrigerant pipe 17 connects between the bottom of the intercooler 5 and the evaporator 7, and a refrigerant pipe 18 connects between the top of the intercooler 5 and the middle stage of the turbo compressor 2. The refrigerant pipe 16 is provided with the high-pressure expansion valve 4, and the refrigerant pipe 17 is provided with the low-pressure expansion valve 6.

[First Embodiment]
2 to 4 show a first embodiment of the evaporator 7.
As shown in FIG. 2, the evaporator 7 is provided in a cylindrical shell-shaped pressure vessel 21 extending in the horizontal direction, a refrigerant inlet 22 provided in the lower portion of the pressure vessel 21, and an upper portion of the pressure vessel 21. It comprises a refrigerant outlet 23, a heat transfer tube group 25 passing through the inside of the pressure vessel 21 in the longitudinal axis direction, a refrigerant distribution plate 26, and a demister 27.

The refrigerant inlet 22 and the refrigerant outlet 23 are respectively arranged in the middle portion in the longitudinal axis direction of the pressure vessel 21, and the refrigerant inlet 22 is formed in a short pipe shape extending horizontally and tangentially from the bottom portion of the pressure vessel 21, The refrigerant outlet 23 is formed in a short pipe shape extending vertically upward from the upper portion of the pressure vessel 21. As shown in FIG. 1, the refrigerant inlet 22 is connected to the refrigerant pipe 17 extending from the bottom portion of the intercooler 5, and the refrigerant outlet 23 is connected to the suction pipe 14 of the turbo compressor 2.

Inside the pressure vessel 21, an inlet chamber 31 is provided below one end (for example, the left end in FIG. 2), and an outlet chamber 32 is provided above the inlet chamber 31 as independent chambers. A U-turn chamber 33 is provided as an independent room at the other end (for example, the right end in FIG. 2) inside the pressure vessel 21. All of these chambers 31, 32 and 33 are arranged below the demister 27. The inlet chamber 31 is provided with an inlet nozzle 34, and the outlet chamber 32 is provided with an outlet nozzle 35.

As shown in FIG. 2, FIG. 3 and FIG. 4, the heat transfer tube group 25 is a forward tube group extending from one end (left end in FIG. 2) in the longitudinal axis direction inside the pressure vessel 21 to the other end (right end in FIG. 2). 25A and a return pipe group 25B communicating with the outward pipe group 25A at the other end in the longitudinal direction inside the pressure container 21 and returning from the other end in the longitudinal axis direction inside the pressure container 21 to one end. Specifically, the forward pipe group 25A is arranged so as to connect between the inlet chamber 31 and the lower part of the U-turn chamber 33, and the return pipe group 25B connects between the outlet chamber 32 and the upper part of the U-turn chamber 33. It is arranged to connect. That is, the outward pipe group 25A is arranged below the inside of the pressure container 21, and the return pipe group 25B is arranged above the inside of the pressure container 21.

From the inlet nozzle 34, for example, water (tap water, purified water, distilled water, etc.) flows in as a liquid to be cooled that is cooled by the refrigerant. The water flows in from the inlet chamber 31 through the outward pipe group 25A, makes a U-turn in the U-turn chamber 33, then flows through the return pipe group 25B, and then flows out as cold water from the outlet nozzle 35 through the outlet chamber 21.

As shown in FIG. 3 and FIG. 4, in the forward path tube group 25A and the return path tube group 25B that form the heat transfer tube group 25, a plurality of heat transfer tube bundles 25a in which a large number of heat transfer tubes are bundled are arranged in the horizontal direction (for example, four heat transfer tube groups 25a). Each) is arranged in parallel. A space S1 extending in the vertical direction is formed between each heat transfer tube bundle 25a. Further, a space S2 extending in the horizontal direction is formed between the outward pipe group 25A and the return pipe group 25B.

As shown in FIG. 2, the individual heat transfer tubes forming the heat transfer tube group 25 (25A, 25B) are fixed inside the pressure vessel 21 while being supported by the plurality of heat transfer tube support plates 37 inside the pressure vessel 21. ing. These heat transfer tube support plates 37 are flat plates having a surface direction that intersects the longitudinal axis direction of the pressure vessel 21, and are arranged in plural at intervals in the longitudinal axis direction of the pressure vessel 21. It is fixed. A large number of through holes are formed in the heat transfer tube support plate 37, and the heat transfer tubes are densely inserted into these through holes.

The heat transfer tube support plate 37 is installed along the longitudinal axis of the pressure vessel 21 near the upstream position of the heat transfer tube group 25, that is, near the upstream position of the forward tube group 25A (left side in FIG. 2). The installation interval L1 is smaller than the installation interval L2 at other positions. For example, L1 is about half of L2.

On the other hand, as shown in FIGS. 2 to 4, the refrigerant distribution plate 26 is installed inside the pressure vessel 21 between the refrigerant inlet 22 and the heat transfer tube group 25 (outgoing tube group 25A). The refrigerant distribution plate 26 is a plate-shaped member having a large number of refrigerant circulation holes 26a.

The area ratio of the refrigerant flow holes 26a per unit area in the refrigerant distribution plate 26 is within a range A1 corresponding to the vicinity of the upstream side position of the heat transfer tube group 25 (25A), for example, in the middle of the heat transfer tube group 25. It is set larger than the range A2 corresponding to the position of the section. Further, the area ratio of the refrigerant circulation holes 26a is set to be larger in the ranges A1 and A3 at both ends in the longitudinal axis direction of the refrigerant distribution plate 26 than in the range A2 in the longitudinal direction middle part. For example, the area ratio of the refrigerant flow holes 26a in the ranges A1 and A3 can be 33 to 38%, and the area ratio of the refrigerant flow holes 26a in the range A2 can be 24 to 33%, but the invention is not limited to this range. ..

As shown in FIG. 3 and FIG. 4, the refrigerant distribution plate 26 is provided vertically below the space S1 extending in the vertical direction formed between the plurality of heat transfer tube bundles 25a forming the heat transfer tube group 25 (25A, 25B). The refrigerant circulation hole 26a is arranged. That is, in plan view, the coolant circulation holes 26a are arranged along the longitudinal direction of the space S1.

As shown in FIGS. 2 to 4, the demister 27 is arranged inside the pressure vessel 21 between the refrigerant outlet 23 and the heat transfer tube group 25 (return tube group 25B). The demister 27 is a member having a high air permeability, for example, in which wires are entwined in a mesh shape, and performs gas-liquid separation of the low-pressure refrigerant. The material is not limited to the wire mesh, and other porous material may be used as long as it has good air permeability.

The demister 27 is attached so that the entire circumference thereof is in contact with the inner circumference of the pressure vessel 21, and the inner space of the pressure vessel 21 is divided into upper and lower parts with the demister 27 as a boundary. Further, the installation height of the demister 27 is set directly above the heat transfer tube group 25. Specifically, the distance between the heat transfer tube group 25 and the demister 27 is about twice the tube arrangement pitch. On the other hand, a relatively large height difference (for example, about 50% or more of the diameter of the pressure vessel 21) is provided between the demister 27 and the refrigerant outlet 23.

In the turbo refrigerating apparatus 1 including the evaporator 7 configured as described above, the turbo compressor 2 is rotationally driven by the electric motor 13 to transfer the gas phase low pressure refrigerant supplied from the evaporator 7 through the suction pipe 14. The compressed low-pressure refrigerant is sent from the discharge pipe 15 to the condenser 3.

Inside the condenser 3, the high-temperature low-pressure refrigerant compressed by the turbo compressor 2 is heat-exchanged with the cooling water to cool the condensation heat to be condensed and liquefied. The low-pressure refrigerant in the liquid phase in the condenser 3 expands by passing through the high-pressure expansion valve 4 provided in the refrigerant pipe 16 extending from the condenser 3 to become a gas-liquid mixed state, and the intercooler. 5, and is temporarily stored there.

Inside the intercooler 5, the low-pressure refrigerant in a gas-liquid mixed state expanded by the high-pressure expansion valve 4 is separated into a gas phase and a liquid phase. The liquid phase component of the low-pressure refrigerant separated here is further expanded by the low-pressure expansion valve 6 provided in the refrigerant pipe 17 extending from the bottom portion of the intercooler 5, and becomes a gas-liquid two-phase flow to become the evaporator 7 Be delivered to. Further, the gas phase component of the low-pressure refrigerant separated by the intercooler 5 is fed to the middle stage part of the turbo compressor 2 via the refrigerant pipe 18 extending from the upper part of the intercooler 5, and is compressed again.

As shown in FIGS. 2 to 4, in the evaporator 7, the low temperature gas-liquid two-phase flow low-pressure refrigerant after adiabatic expansion in the low-pressure expansion valve 6 flows into the pressure vessel 21 from the refrigerant inlet 22. After being dispersed in the longitudinal axis direction of the pressure vessel 21 below the refrigerant distribution plate 26, the refrigerant flows through the refrigerant circulation holes 26 a of the refrigerant distribution plate 26 and flows upward. Then, a pool of low-pressure refrigerant is formed inside the pressure vessel 21. The liquid level of the low-pressure refrigerant pool is automatically adjusted so as to be between the heat transfer tube group 25 and the demister 27.

The heat transfer tube group 25 (25A, 25B) is immersed in the low pressure refrigerant pool inside the pressure vessel 21, and exchanges heat with the low pressure refrigerant. As a result, the water passing through the inside of the heat transfer tube group 25 is cooled and becomes cold water. This cold water is used as a cooling/heating medium for air conditioning or industrial cooling water.

The low-pressure refrigerant evaporated (vaporized) by heat exchange with the heat transfer tube group 25 is gas-liquid separated by the demister 27. That is, when the vaporized low pressure refrigerant (vaporized refrigerant) is directed to the refrigerant outlet 23 inside the pressure vessel 21, a fast flow is formed due to the characteristics of the low pressure refrigerant having a larger specific volume than the high pressure refrigerant. Then, the droplets of the non-evaporated liquid-phase refrigerant blown up from the low-pressure refrigerant pool tend to come out from the refrigerant outlet 23 along with the fast flow of the vaporized refrigerant, which may cause carryover.

However, this droplet is captured and separated by the porous demister 27 and falls into the low-pressure refrigerant pool due to gravity, so carryover is prevented. The vaporized refrigerant thus separated into gas and liquid is discharged from the refrigerant outlet 23, is again sucked and compressed by the turbo compressor 2 via the suction pipe 14, and then this refrigeration cycle is repeated.

In this evaporator 7, the area ratio of the refrigerant flow holes 26a in the refrigerant distribution plate 26 installed between the refrigerant inlet 22 and the heat transfer tube group 25 (25A, 25B) inside the pressure vessel 21 is determined by the heat transfer tube group. The range A1 corresponding to the vicinity of the upstream position of 25 (25A) is made larger than the other ranges A2.

Therefore, the low-pressure refrigerant introduced from the refrigerant inlet 22 into the pressure vessel 21 is distributed in a relatively large amount near the upstream position of the heat transfer tube group 25 (25A). Further, a relatively small amount of low pressure refrigerant is distributed to other positions. As a result, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel 21 is made uniform.

In the vicinity of the position on the upstream side of the heat transfer tube group 25 (25A) inside the evaporator 21, the low-pressure refrigerant boils violently because the temperature difference with the water flowing inside the heat transfer tube group 25 (25A) is large. However, since a relatively large amount of low-pressure refrigerant is distributed to this position as compared with other positions as described above, the vicinity of the upstream side of the heat transfer tube group 25 (25A) is surrounded by the boiling bubbles of the low-pressure refrigerant. Therefore, the heat transfer tube group 25 (25A, 25B) can be maintained in a state in which it is immersed in the refrigerant two-phase liquid. Therefore, the liquid to be cooled and the low-pressure refrigerant flowing inside the heat transfer tube group 25 (25A, 25B) can be favorably heat-exchanged, and the heat transfer performance of the heat transfer tube group 25 (25A, 25B) can be improved. it can.

As described above, the floss level of the low-pressure refrigerant pool does not rise higher than both ends in the longitudinal axis direction in the middle portion in the longitudinal axis direction of the pressure container 21, so that the middle portion in the longitudinal axis direction of the pressure container 21 as in the present embodiment. By providing the refrigerant outlet 23 that communicates with the suction pipe 14 of the turbo compressor 2, it is possible to effectively prevent the liquid-phase refrigerant from carrying over to the turbo compressor 2 side along with the flow of the vaporized refrigerant. It is possible to suppress a decrease in efficiency of the turbo compressor 2.

In addition, in the evaporator 7, the refrigerant inlet 22 is provided in the middle portion in the longitudinal axis direction of the pressure vessel 21, and the area ratio of the refrigerant circulation holes 26 a in the refrigerant distribution plate 26 is such that both end portions in the longitudinal axis direction of the refrigerant distribution plate 26. The ranges A1 and A3 are larger than the range A2 of the intermediate portion in the longitudinal axis direction.

Therefore, the low-pressure refrigerant introduced into the pressure vessel 21 through the refrigerant inlet 22 provided at the longitudinal axis direction intermediate portion of the pressure vessel 21 is largely supplied to both ends of the pressure vessel 21 in the longitudinal axis direction. A relatively small amount is supplied to the intermediate portion in the longitudinal axis direction of the pressure vessel 21 which is immediately above. For this reason, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel 21 is made uniform, and the water flowing inside the heat transfer tube group 25 (25A, 25B) and the low-pressure refrigerant are satisfactorily heat-exchanged and transferred. The heat transfer performance of the heat pipe group 25 (25A, 25B) can be improved.

Further, the heat transfer tube group 25 of the evaporator 7 communicates with the outward path tube group 25A extending from one end in the longitudinal axis direction inside the pressure vessel 21 to the other end, and the outward path tube group 25A at the other end in the longitudinal axis direction inside the pressure vessel 21. The return vessel group 25B that returns from the other end in the longitudinal axis direction to the one end in the pressure vessel 21 is provided. The forward pipe group 25A is arranged below the pressure vessel 21 and the return pipe group 25B is arranged above it.

When the heat transfer tube group 25 is configured in this way, the outward path tube group 25A in which the temperature difference with the water flowing in the heat transfer tube is large and the boiling of the low-pressure refrigerant is intense is arranged in the lower portion of the pressure vessel 21 and flows in the heat transfer tube. A return pipe group 25</b>B in which the temperature difference from water is small and the boiling of the low-pressure refrigerant is gentle is arranged above the pressure vessel 21.

Therefore, the low-pressure refrigerant is vigorously boiled below the liquid surface of the low-pressure refrigerant pool in the pressure vessel 21 (deep part), and the liquid-phase refrigerant is less likely to be scattered on the liquid surface of the low-pressure refrigerant pool. Therefore, it is possible to prevent the liquid-phase refrigerant from being carried over to the turbo compressor 2 side by being accompanied by the flow of the vaporized refrigerant, and to suppress the efficiency reduction of the turbo compressor 2.

In the heat transfer tube group 25 (25A, 25B), a plurality of heat transfer tube bundles 25a in which a plurality of heat transfer tubes are bundled are arranged in the horizontal direction, and a space S1 extending vertically is formed between the heat transfer tube bundles 25a. There is.

The vertical void S1 between the plurality of heat transfer tube bundles 25a serves as a path for boiling bubbles of the low-pressure refrigerant that has boiled by exchanging heat with the heat transfer tube group 25 (25A, 25B). Thereby, the boiling bubbles can easily float on the liquid surface of the low-pressure refrigerant pool. Therefore, it is possible to prevent the heat transfer tube group 25 (25A, 25B) from being surrounded by boiling bubbles and being dried out under the liquid surface of the refrigerant, and to improve the heat transfer performance of the heat transfer tube group 25 (25A, 25B).

In addition to this, since the coolant distribution hole 26a formed in the coolant distribution plate 26 is arranged vertically below the space S1, the coolant distribution hole 26a of the coolant distribution plate 26 is discharged upward. The flow of the low-pressure refrigerant passes through the space S1 and reaches the upper end of the heat transfer tube group 25 (25A, 25B). Therefore, the heat transfer performance of the heat transfer tube group 25 (25A, 25B) can be improved.

When a low-pressure refrigerant is used as in the turbo refrigerator 1, the gas flow velocity inside the pressure vessel 21 of the evaporator 7 becomes faster due to the characteristics of the low-pressure refrigerant having a larger specific deposition than the high-pressure refrigerant. For this reason, the distance until the droplets of the liquid-phase refrigerant blown up from the low-pressure refrigerant pool inside the pressure vessel 21 are separated from the vapor-phase refrigerant by its own weight becomes relatively long. Therefore, if the demister 27 is installed at a position higher than the position where the droplets are separated by their own weight, the distance from the liquid surface of the refrigerant to the demister 27 becomes long and the shell diameter of the pressure vessel 21 becomes large.

In this evaporator 7, by disposing the demister 27 directly above the heat transfer tube group 25, the amount of droplets ejected from the low-pressure refrigerant pool is reduced by the demister 27, and droplets of the low-pressure refrigerant emerge from the refrigerant outlet 23. Suppressing carryover.
Furthermore, by disposing the demister 27 directly above the heat transfer tube group 25, the space height above the demister 27 is relatively increased, and the evaporation mist of the low-pressure refrigerant is promoted to become droplets with a large diameter. The carry-over of the low-pressure refrigerant can also be suppressed in this respect by reducing the distance by which the droplets are separated by their own weight.

Further, in this evaporator 7, the demister 27 is provided so that the entire circumference thereof is in contact with the entire inner circumference of the pressure vessel 21. As a result, the entire amount of the gas flow of the low-pressure refrigerant inside the pressure vessel 21 passes through the demister 27, and the flow resistance of the gas flow increases. Therefore, the flow velocity distribution of the gas flow in the pressure vessel 21 is leveled, the peak value of the local gas flow velocity is reduced, the amount of droplets generated is reduced, and the self-weight separation distance of the droplets is shortened. Carryover of the low pressure refrigerant can be prevented.

In addition, in the evaporator 7, the installation interval L1 of the plurality of heat transfer tube support plates 37 supporting the individual heat transfer tubes of the heat transfer tube group 25 in the vicinity of the position on the upstream side of the heat transfer tube group 25 is different from other positions. Is smaller than the installation interval L2.

In the vicinity of the position on the upstream side of the heat transfer tube group 25, as described above, the temperature difference between the water flowing inside the heat transfer tube group 25 and the low pressure refrigerant is large, so that the low pressure refrigerant is boiled violently, and the specific volume of the boiling bubbles is Since it is larger than the high-pressure refrigerant, it generates more vibration than when the high-pressure refrigerant is used. Therefore, there is a concern that the heat transfer tube group 25 resonates with the vibration of the boiling bubbles and is damaged.

As described above, by setting the installation interval L1 of the heat transfer tube support plate 37 near the position on the upstream side of the heat transfer tube group 25 to be smaller than the installation interval L2 at other positions, the vicinity of the upstream side of the heat transfer tube group 25. The installation rigidity can be increased, resonance can be suppressed, and damage can be prevented.

[Second Embodiment]
FIG. 5 is a side view of an evaporator showing a second embodiment of the present invention.
This evaporator 7A is different from the evaporator 7 (refrigerant inlet 22) of the first embodiment in that a plurality of refrigerant inlets 22A of the pressure vessel 21 are provided dispersed along the longitudinal axis direction of the pressure vessel 21. However, the other configurations are the same. Therefore, the same reference numerals are given to the respective parts having the same configuration, and the description thereof will be omitted.

In the present embodiment, for example, two refrigerant inlets 22A are provided so as to be dispersed along the longitudinal axis direction of the pressure vessel 21 and to be separated from each other. The refrigerant inlet 22A may be provided at three or more places. Like the refrigerant inlet 22 of the first embodiment, these refrigerant inlets 22A are formed in a short pipe shape extending horizontally and tangentially from the bottom of the pressure vessel 21. The diameter of each refrigerant inlet 22A is smaller than the diameter of the refrigerant inlet 22 of the first embodiment.

As described above, since the low-pressure refrigerant has a larger specific volume than the high-pressure refrigerant, the volumetric flow rate flowing into the evaporator 7A is large and the dynamic pressure is high, but the refrigerant circulation hole 26a of the refrigerant distribution plate 26 is made small accordingly. If the pressure loss is increased by, for example, increasing the speed at which the low-pressure refrigerant is ejected from the refrigerant flow holes 26a, the vibration and damage of the heat transfer tube group 25 will occur.

Like the evaporator 7A, two or three or more refrigerant inlets 22A are provided separately from each other along the longitudinal axis direction of the pressure vessel 21, so that a single refrigerant inlet 22 as in the first embodiment is provided. The inflow rate of the low-pressure refrigerant into the pressure vessel 21 can be reduced as compared with the case where the pressure vessel 21 is provided. For this reason, the diameter of the refrigerant distribution hole 26a of the refrigerant distribution plate 26 can be increased, and thus the speed at which the low-pressure refrigerant is ejected from the refrigerant distribution hole 26a can be reduced.

This prevents vibration and damage to the heat transfer tube group 25, and suppresses carry-over of the liquid-phase low-pressure refrigerant locally to the turbo compressor 2 side, for example, to suppress the carry-over. It is possible to avoid a decrease in efficiency.

[Third Embodiment]
FIG. 6 is a vertical cross-sectional view of an evaporator showing a third embodiment of the present invention, and FIG. 7 is a view on arrow VII of FIG.
In this evaporator 7B, the flow passage cross-sectional area from the outer opening 22a of the refrigerant inlet 22 provided at the bottom of the pressure container 21 to the pressure container 21 is increased from the outer opening 22a toward the pressure container 21. There is. Specifically, the expansion flow path 22b is provided between the outer opening 22a and the pressure vessel 21. The other configurations are the same as those of the evaporator 7 of the first embodiment shown in FIG. 3, and therefore, the same reference numerals are given to the respective portions having the same configuration and the description thereof will be omitted.

The expansion flow channel 22b is formed in a box shape, for example, and has a flow channel cross-sectional area larger than that of the refrigerant inlet 22. For example, the flow passage cross-sectional area of the expansion flow passage 22b is set to about 2 to 5 times the flow passage cross-sectional area of the refrigerant inlet 22. The shape of the expansion flow channel 22b is not limited to the box shape, and may be any other shape as long as the flow channel cross-sectional area is larger than the outer opening 22a of the refrigerant inlet 22. For example, the expansion flow path 22b may have a bulge shape or the like. Further, it is conceivable that the refrigerant inlet 22 is formed in a tapered tubular shape whose diameter increases from the outer opening 22a toward the pressure vessel 21 side without providing the expansion flow passage 22b.

In this way, the flow passage cross-sectional area from the outer opening 22a of the refrigerant inlet 22 to the pressure container 21 is enlarged toward the pressure container 21, so that the flow velocity of the low-pressure refrigerant flowing through the refrigerant inlet 22 is directed toward the pressure container 21. descend.
Therefore, the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation holes 26a of the refrigerant distribution plate 26 is reduced to prevent vibration and damage of the heat transfer tube group 25, and the liquid-phase low-pressure refrigerant is locally ejected. As a result, carryover to the turbo compressor 2 side can be suppressed, and a decrease in efficiency of the turbo compressor 2 can be avoided.

[Fourth Embodiment]
8A and 8B are vertical cross-sectional views of an evaporator showing a fourth embodiment of the present invention.
This evaporator 7C differs from the evaporator 7 (refrigerant inlet 22) of the first embodiment in that a flow velocity attenuating member for attenuating the flow velocity of the low-pressure refrigerant is provided inside the pipe of the refrigerant inlet 22, and other configurations. Are the same.

As the flow velocity attenuating member, as shown in FIG. 8A, a perforated plate (punching plate or the like) 22c is installed in the pipe of the refrigerant inlet 22, or as shown in FIG. It is possible to install a plurality of baffles 22d in a maze. As long as the flow velocity of the low-pressure refrigerant in the pipe of the coolant inlet 22 can be attenuated, other components may be installed as the flow velocity attenuating member.

Thus, by providing the flow velocity attenuating members 22c and 22d in the pipe of the refrigerant inlet 22, the flow velocity of the low pressure refrigerant flowing from the refrigerant inlet 22 into the pressure vessel 21 is reduced.
Therefore, the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation holes 26a of the refrigerant distribution plate 26 is reduced to prevent vibration and damage of the heat transfer tube group 25, and the liquid-phase low-pressure refrigerant is locally ejected. As a result, it is possible to suppress carryover to the turbo compressor 2 side and avoid a decrease in efficiency of the turbo compressor 2.

As described above, according to the evaporators 7, 7A, 7B, 7C and the turbo refrigeration system 1 including these evaporators according to the present embodiment, the low-pressure refrigerant used at the maximum pressure of less than 0.2 MPaG. In the turbo refrigerating apparatus 1 using, the heat transfer performance is improved by preventing the dry-out of the heat transfer tubes 25 in the evaporator, and the liquid phase low pressure refrigerant is carried over to the turbo compressor 2 side. It is possible to suppress a decrease in efficiency.

Note that the present invention is not limited to the configurations of the above-described embodiments, and modifications and improvements can be appropriately added. Embodiments thus modified or improved are also included in the scope of rights of the present invention. And For example, the first to fourth embodiments described above may be combined.

1 Turbo Refrigerator 2 Turbo Compressor 3 Condenser 7 Evaporator 21 Pressure Vessel 22 Refrigerant Inlet 22a Refrigerant Inlet Outer Opening 22b Expansion Channel 22c Perforated Plate (Flow Rate Damping Member)
22d Baffle plate (flow velocity damping member)
23 Refrigerant outlet 25 Heat transfer tube group 25A Forward path tube group 25B Return path tube group 25a Heat transfer tube bundle 26 Refrigerant distribution plate 26a Refrigerant distribution hole 27 Demister 37 Heat transfer tube support plate A1 Range corresponding to the vicinity of the upstream side of the heat transfer tube group (refrigerant Range of the longitudinal end of the distribution plate)
A2 Range corresponding to other positions of the heat transfer tube group (range of the intermediate portion in the longitudinal axis direction of the refrigerant distribution plate)
A3 Range of end portions in the longitudinal axis direction of the refrigerant distribution plate L1, L2 Installation interval S1 of heat transfer tube support plate S1 Void

Claims (12)

A pressure vessel that extends in the horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced,
A refrigerant inlet provided at the bottom of the pressure vessel,
A refrigerant outlet provided in the upper part of the pressure vessel,
A heat transfer tube group that passes through the inside of the pressure vessel in the longitudinal axis direction, circulates the liquid to be cooled therein, and heat-exchanges the liquid to be cooled with the low-pressure refrigerant,
A plate-shaped refrigerant distribution plate provided between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant flow hole formed therein;
The heat transfer tube group communicates with the forward path tube group extending from one end to the other end in the longitudinal axis direction inside the pressure vessel, and the forward path tube group at the other end in the longitudinal axis direction inside the pressure vessel, and the longitudinal direction inside the pressure vessel. And a return pipe group that returns from the other end in the axial direction to one end,
The heat transfer tube group is supported by a flat plate heat transfer tube support plate having a surface direction intersecting the longitudinal axis direction of the pressure vessel,
The area ratio of the refrigerant flow holes per unit area in the refrigerant distribution plate is made larger than other ranges in the range corresponding to the upstream side position of each of the outward pipe group and the return pipe group, An evaporator characterized in that a range corresponding to the vicinity of the refrigerant outlet is made smaller than other ranges. The refrigerant inlet is provided at an intermediate portion in the longitudinal direction of the pressure vessel,
The evaporator according to claim 1, wherein the area ratio of the refrigerant flow holes in the refrigerant distribution plate is larger in a range of an end portion in the longitudinal axis direction of the refrigerant distribution plate than in a range of an intermediate portion in the longitudinal axis direction. Individual heat transfer tubes constituting the heat transfer tube group is placed is through a plurality of the heat transfer tube support plates arranged at intervals in the longitudinal direction of the front Symbol pressure vessel, upstream of the heat transfer tube group The evaporator according to claim 1 or 2 , wherein an installation interval of the heat transfer tube support plate in the vicinity of the position is smaller than an installation interval of the heat transfer tube support plate in another position. A pressure vessel that extends in the horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced,
A refrigerant inlet provided at the bottom of the pressure vessel,
A refrigerant outlet provided in the upper part of the pressure vessel,
A heat transfer tube group that passes through the inside of the pressure vessel in the longitudinal axis direction, circulates the liquid to be cooled therein, and heat-exchanges the liquid to be cooled with the low-pressure refrigerant,
A plate-shaped refrigerant distribution plate provided between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant flow hole formed therein;
The refrigerant inlet is provided in a plurality dispersed along the longitudinal direction of the pressure vessel ,
Each heat transfer tube constituting the heat transfer tube group has a plurality of heat transfer tube support plates which have a surface direction intersecting the longitudinal axis direction of the pressure vessel and are arranged at intervals in the longitudinal axis direction of the pressure vessel. An evaporator characterized in that an installation interval of the heat transfer tube support plates in the vicinity of a position on the upstream side of the heat transfer tube group is smaller than an installation interval of the heat transfer tube support plates in other positions . .. A pressure vessel that extends in the horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced,
A refrigerant inlet provided at the bottom of the pressure vessel,
A refrigerant outlet provided in the upper part of the pressure vessel,
A heat transfer tube group that passes through the inside of the pressure vessel in the longitudinal axis direction, circulates the liquid to be cooled therein, and heat-exchanges the liquid to be cooled with the low-pressure refrigerant,
A plate-shaped refrigerant distribution plate provided between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant flow hole formed therein;
The flow path cross-sectional area from the outer opening of the refrigerant inlet to the pressure vessel is expanding from the outer opening toward the pressure vessel ,
Each heat transfer tube constituting the heat transfer tube group has a plurality of heat transfer tube support plates which have a surface direction intersecting the longitudinal axis direction of the pressure vessel and are arranged at intervals in the longitudinal axis direction of the pressure vessel. An evaporator characterized in that an installation interval of the heat transfer tube support plates in the vicinity of a position on the upstream side of the heat transfer tube group is smaller than an installation interval of the heat transfer tube support plates in other positions . .. A pressure vessel that extends in the horizontal direction and into which a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG is condensed and introduced,
A refrigerant inlet provided at the bottom of the pressure vessel,
A refrigerant outlet provided in the upper part of the pressure vessel,
A heat transfer tube group that passes through the inside of the pressure vessel in the longitudinal axis direction, circulates the liquid to be cooled therein, and heat-exchanges the liquid to be cooled with the low-pressure refrigerant,
A plate-shaped refrigerant distribution plate provided between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant flow hole formed therein;
The refrigerant inlet is tubular connected to the pressure vessel, a flow velocity damping member for damping the flow velocity of the low pressure refrigerant is provided in the pipe ,
Each heat transfer tube constituting the heat transfer tube group has a plurality of heat transfer tube support plates which have a surface direction intersecting the longitudinal axis direction of the pressure vessel and are arranged at intervals in the longitudinal axis direction of the pressure vessel. An evaporator characterized in that an installation interval of the heat transfer tube support plates in the vicinity of a position on the upstream side of the heat transfer tube group is smaller than an installation interval of the heat transfer tube support plates in other positions . .. The heat transfer tube group,
A forward tube group extending from one end to the other end in the longitudinal direction inside the pressure vessel,
A return path tube group communicating with the outward path tube group at the other end in the longitudinal axis direction inside the pressure vessel, and returning from the other end in the longitudinal axis direction inside the pressure vessel to one end,
The evaporator according to any one of claims 1 to 6 , wherein the outward pipe group is arranged below the inside of the pressure vessel, and the return pipe group is arranged above. The heat transfer tube group is a plurality of heat transfer tubes are arrayed in the heat transfer tube bundle is horizontal bundled, according to any of claims 1 to 7 in which the air gap extending in the vertical direction in the heat transfer tube bundles is formed Evaporator. The evaporator according to claim 8 , wherein the refrigerant circulation hole formed in the refrigerant distribution plate is arranged vertically below the gap. Located between the heat transfer tube group and the coolant outlet in the interior of the pressure vessel, demister for gas-liquid separation of the low-pressure refrigerant, claim 1, which is disposed directly above the heat transfer tube group 9 The evaporator according to any one of 1. The evaporator according to claim 10 , wherein the demister is provided such that the entire circumference thereof is in contact with the inner circumference of the pressure vessel. A turbo compressor that compresses a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG,
A condenser for condensing the compressed low-pressure refrigerant,
The evaporator according to any one of claims 1 to 11, which evaporates the expanded low-pressure refrigerant,
A turbo refrigerating apparatus comprising:

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