JP2017072343A - Evaporator and turbo refrigerator having evaporator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict efficiency deterioration due to the caring-over of liquid phase low pressure refrigerant on the side of a turbo compressor while the heat transfer performance is improved by preventing the dry out of the heat transfer tube group within the evaporator in a turbo refrigerator using the low pressure refrigerant used at a high pressure less than 0.2 MPaG.SOLUTION: An evaporator 7 comprises: a pressure container 21 that is extending in a horizontal direction in that the low pressure refrigerant used at a high pressure less than 0.2 MPaG is condensed and introduced; a refrigerant inlet 22 provided at a lower part of the pressure container 21; a refrigerant outlet 23; a heat transfer tube group 25 that passes through the interior of the pressure container 21 in a longitudinal axial direction for heat exchanging with pressure refrigerant; and a tabular refrigerant distribution plate 26 that is installed between the refrigerant inlet 22 and the heat transfer tube group 25 in that a refrigerant flow hole 26a is bored, in which the area ratio of the refrigerant flow hole 26a per unit area in the refrigerant distribution plate 26 is larger in a range A1 corresponding to the vicinity of the position on the upstream side of the heat transfer tube group 25 than that in the other range A2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an evaporator for vaporizing a low-pressure refrigerant and a turbo refrigeration apparatus including the evaporator.

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

  As disclosed in Patent Document 1, the evaporator has a cylindrical shell-shaped pressure vessel, and a heat transfer tube that allows a liquid to be cooled such as water to pass through the pressure vessel in the longitudinal axis direction. Groups are arranged. In addition, a distribution plate (refrigerant distribution plate) in which a large number of refrigerant flow holes are formed is provided below the heat transfer tube group, and an eliminator (demister) is provided above the heat transfer tube group. Yes.

  The liquid-phase refrigerant compressed by the turbo compressor and condensed by the condenser flows into the pressure vessel from the refrigerant inlet provided at the lower portion of the pressure vessel, and passes through a number of refrigerant circulation holes of the distribution plate. Thus, heat is exchanged with the heat transfer tube group while diffusing throughout the interior of the pressure vessel. Thereby, 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 medium for air conditioning or an industrial cooling liquid.

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

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

  Moreover, the eliminator was arrange | positioned in the position sufficiently higher than the liquid level of the refrigerant | coolant in a pressure vessel. The reason for this is to prevent the so-called carryover (gas-liquid entrainment) in which the liquid droplets of the boiled refrigerant pass through the eliminator and enter the suction pipe in a liquid state, thereby suppressing the efficiency reduction of the turbo compressor. It is.

Japanese Patent Laid-Open No. 61-280359

  Low-pressure refrigerants such as R1233zd used at a maximum pressure of less than 0.2 MPaG are expected as next-generation refrigerants because they can increase the efficiency of turbo refrigeration equipment and have a low global warming potential.

  Since such a low-pressure refrigerant has a characteristic that the gas specific volume is larger than that of a high-pressure refrigerant such as R134a, the boiling bubbles increase when the heat exchanger boiles inside the evaporator and boil. Therefore, the heat transfer tube group is locally surrounded by boiling bubbles, so-called dry out is likely to occur, and the heat transfer performance tends to be lower than in a state where the heat transfer tube group is immersed in the refrigerant two-phase liquid. .

  In addition, in the upstream part of the heat transfer tube group inside the evaporator, the refrigerant boils violently because the temperature difference between the liquid to be cooled and the refrigerant flowing inside the heat transfer tube group is large, but in the downstream part of the heat transfer tube group, the above temperature difference As the temperature shrinks, the boiling of the refrigerant becomes gentle. For this reason, it becomes difficult to set and adjust the liquid level (floss level) of the liquid-phase refrigerant pool inside the evaporator.

  Furthermore, since the gap flow velocity is increased in the heat transfer tube group, there is a concern about fatigue failure due to the drag applied to each heat transfer tube. In addition, when using a low-pressure refrigerant, the volume flow rate of the vaporized refrigerant sucked into the turbo compressor from the evaporator is much larger than that of the high-pressure refrigerant, so that the flow rate of the vaporized refrigerant inside the evaporator becomes high, and the vaporized refrigerant The liquid-phase refrigerant is likely to carry over to the turbo compressor side on the flow, and there is a concern that the efficiency of the turbo compressor may be reduced.

  The present invention has been made in view of such circumstances, and in a turbo refrigeration apparatus using a low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG, prevents the heat transfer tube group from being dried out in the evaporator. It is an object of the present invention to provide an evaporator capable of improving the heat transfer performance and suppressing a decrease in efficiency due to the liquid phase low-pressure refrigerant being carried over to the turbo compressor side, and a turbo refrigeration apparatus equipped with 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 part 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. A refrigerant inlet, a refrigerant outlet provided at an upper portion of the pressure vessel, and the inside of the pressure vessel in a longitudinal axis direction, a liquid to be cooled is circulated therein, and the liquid to be cooled is heated with the low-pressure refrigerant and heat. A heat transfer tube group to be exchanged, and a plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel and having a refrigerant flow hole formed therein, and the refrigerant The area ratio of the refrigerant circulation holes per unit area in the distribution plate is larger in the range corresponding to the position near the upstream side of the heat transfer tube group than in other ranges.

  As described above, the area ratio of the refrigerant flow holes per unit area in the refrigerant distribution plate is larger than the other ranges in the range corresponding to the vicinity of the upstream position of the heat transfer tube group, so that the refrigerant inlet into 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. A relatively small amount of low-pressure refrigerant is distributed to other positions. Thereby, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel is made uniform.

  In the vicinity of the position upstream of the heat transfer tube group in the evaporator, the low-pressure refrigerant boils violently because the temperature difference with the liquid to be cooled flowing inside the heat transfer tube group is large. However, since a relatively large amount of low-pressure refrigerant is distributed to this position as compared with other positions, the position near the upstream side of the heat transfer tube group is surrounded by the low-pressure refrigerant boiling bubbles and does not dry out. The state where the heat transfer tube group is immersed in the refrigerant two-phase liquid can be maintained. For this reason, the to-be-cooled liquid which flows through the inside of the heat transfer tube group and the low-pressure refrigerant can be favorably exchanged heat, and the heat transfer performance of the heat transfer tube group can be enhanced.

  In addition, since the floss level of the low-pressure refrigerant pool does not rise at both ends of the pressure vessel in the longitudinal direction intermediate portion of the pressure vessel, the refrigerant communicated with the suction pipe of the turbo compressor at the longitudinal direction intermediate portion 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 the flow of the vaporized refrigerant, and to suppress the efficiency reduction of the turbo compressor.

  In the evaporator, the refrigerant inlet is provided in 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 an end portion in the longitudinal axis direction of the refrigerant distribution plate. It is good also as a structure larger than the range of a longitudinal-axis direction intermediate part.

  According to the evaporator configured as described above, a large amount of the low-pressure refrigerant introduced into the pressure vessel from the refrigerant inlet provided in the intermediate portion in the longitudinal axis direction of the pressure vessel is supplied to both ends in the longitudinal axis direction inside the pressure vessel. A relatively small amount is supplied to the intermediate portion in the longitudinal axis direction of the pressure vessel, which is directly 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 so that the liquid to be cooled and the low-pressure refrigerant flowing inside the heat transfer pipe group can exchange heat well, and the heat transfer of the heat transfer pipe group Performance can be increased.

  The evaporator according to the second aspect of the present invention is provided in a lower part 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. A refrigerant inlet, a refrigerant outlet provided at an upper portion of the pressure vessel, and the inside of the pressure vessel in a longitudinal axis direction, a liquid to be cooled is circulated therein, and the liquid to be cooled is heated with the low-pressure refrigerant and heat. A heat transfer tube group to be exchanged, and a plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel and having a refrigerant flow hole formed therein, and the refrigerant A plurality of inlets are provided in a distributed manner along the longitudinal direction of the pressure vessel.

  Since the specific volume of the low-pressure refrigerant is larger than that of the high-pressure refrigerant, the volume flow rate flowing from the refrigerant inlet to the evaporator is large and the dynamic pressure is high. The speed of ejection from the refrigerant circulation hole of the distribution plate increases, leading to vibration and breakage of the heat transfer tube group.

  According to the evaporator having the above-described configuration, a plurality of refrigerant inlets are provided along the longitudinal axis direction of the pressure vessel, so that the inflow rate of the low-pressure refrigerant is reduced compared to a case where the refrigerant inlet is single. be able to. For this reason, the diameter of the refrigerant circulation hole of the refrigerant distribution plate can be increased, thereby reducing the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation hole, and the vibration and breakage of the heat transfer tube group can be prevented.

  In addition, the low-pressure refrigerant can be uniformly introduced from the plurality of refrigerant inlets over the entire length in the longitudinal axis of the pressure vessel, so that the floss level of the low-pressure refrigerant pool inside the pressure vessel can be made uniform. As a result, the heat transfer performance is improved by preventing the heat transfer tube group from being dried out, and the liquid phase low-pressure refrigerant is locally blown up and suppressed from being carried over to the turbo compressor side. A reduction in the efficiency of the compressor can be avoided.

  The evaporator according to the third aspect of the present invention is provided in a lower part 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. A refrigerant inlet, a refrigerant outlet provided at an upper portion of the pressure vessel, and the inside of the pressure vessel in a longitudinal axis direction, a liquid to be cooled is circulated therein, and the liquid to be cooled is heated with the low-pressure refrigerant and heat. A heat transfer tube group to be exchanged, and a plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel and having a refrigerant flow hole formed therein, and the refrigerant A flow path cross-sectional area from the outer opening of the inlet to the pressure vessel is enlarged from the outer opening toward the pressure vessel.

According to the evaporator configured as described above, the flow path cross-sectional area from the outer opening of the refrigerant inlet to the pressure vessel increases toward the pressure vessel, so the flow rate of the low-pressure refrigerant flowing through the refrigerant inlet decreases toward the pressure vessel. .
For this reason, the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation holes of the refrigerant distribution plate is reduced to prevent vibration and breakage of the heat transfer tube group, and the liquid-phase low-pressure refrigerant is locally blown up and turbo compressed. Carrying over to the machine side can be suppressed, and a reduction in efficiency of the turbo compressor can be avoided.

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

According to the evaporator having the above configuration, the flow rate of the low-pressure refrigerant flowing into the pressure vessel from the refrigerant inlet is reduced by the flow velocity attenuating member.
For this reason, the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation holes of the refrigerant distribution plate is reduced to prevent vibration and breakage of the heat transfer tube group, and the liquid-phase low-pressure refrigerant is locally blown up and turbo compressed. Carrying over to the machine side can be suppressed, and a reduction in efficiency of the turbo compressor can be avoided.

  In any of the above evaporators, the heat transfer tube group includes an outward tube group extending from one longitudinal end to the other end in the pressure vessel, and an outward tube group at the other longitudinal end in the pressure vessel. A return pipe group that communicates and returns from the other end in the longitudinal axis direction to the one end in the longitudinal direction of the pressure vessel, and the forward tube group is disposed below and the return tube group is disposed above in the pressure vessel. A configuration may be adopted.

According to the evaporator having the above configuration, the outgoing pipe group in which the temperature difference from the liquid to be cooled flowing in the heat transfer pipe is large and the boiling of the low-pressure refrigerant is intense is arranged at the lower part of the pressure vessel, and the temperature difference from the liquid to be cooled is A return pipe group in which the boiling of the small low-pressure refrigerant is gentle is arranged at the top of the pressure vessel.
For this reason, intense boiling of the low-pressure refrigerant is performed below the liquid level of the low-pressure refrigerant pool in the pressure vessel, and the liquid-phase refrigerant is less likely to scatter on the liquid level of the low-pressure refrigerant pool. Accordingly, it is possible to prevent the liquid-phase refrigerant from being carried over to the turbo compressor side accompanying 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 is configured such that 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 extending in the vertical direction is formed between the heat transfer tube bundles. Also good.

  According to the evaporator having the above configuration, the vertical gap between the plurality of heat transfer tube bundles becomes a passage for the boiling bubbles of the low-pressure refrigerant boiled by heat exchange with the heat transfer tube group. Thereby, the boiling bubbles can easily float on the liquid level of the low-pressure refrigerant. Therefore, it is possible to prevent the heat transfer tube group from being surrounded by boiling bubbles and drying out under the refrigerant liquid level, and to improve the heat transfer performance of the heat transfer tube group.

  In the 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-described configuration, the flow of the low-pressure refrigerant that passes through the refrigerant flow hole formed in the refrigerant distribution plate and is discharged upward passes through the gap and reaches the upper end of the heat transfer tube group. The heat transfer performance of the heat tube group can be enhanced.

  In any of the above evaporators, a demister that is positioned between the refrigerant outlet and the heat transfer tube group inside the pressure vessel and performs gas-liquid separation of the refrigerant is disposed immediately above the heat transfer tube group. A configuration may be adopted.

  When the low-pressure refrigerant is used, the gas flow rate is large, and therefore the distance until the droplets of the liquid-phase refrigerant that spouts are separated from the gas-phase refrigerant by its own weight becomes relatively long. For this reason, if the demister is installed at a position higher than the position where the droplets separate by their own weight, the distance from the coolant level to the demister becomes longer, and the shell diameter of the pressure vessel becomes larger.

  By disposing the demister directly above the heat transfer tube group as described above, the amount of droplets ejected can be reduced by the demister, and the carry-over amount can be reduced. Furthermore, by placing the demister directly above the heat transfer tube group, the evaporation mist of the low-pressure refrigerant is promoted to become a large diameter droplet in the space above the demister, and the distance at which the droplet separates by its own weight is reduced to reduce the pressure. The carry over of the refrigerant can be prevented.

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

  According to the evaporator configured as described above, the entire amount of the gas flow of the low-pressure refrigerant inside the pressure vessel must pass through the demister, and the flow resistance of the gas flow increases. For this reason, the flow velocity distribution of the gas flow in the pressure vessel is leveled, the peak value of the local gas flow velocity is lowered, the amount of droplets generated is reduced, and the self-weight separation distance of the droplets is shortened. The carry over of the refrigerant can be prevented.

  In any one of the evaporators described above, the individual heat transfer tubes constituting the heat transfer tube group have a surface direction intersecting with the longitudinal axis direction of the pressure vessel and are spaced in the longitudinal axis direction of the pressure vessel. The heat transfer tube support plate is installed penetrating through the plurality of arranged heat transfer tube support plates, and the heat transfer tube support plate installation interval in the vicinity of the upstream position of the heat transfer tube group is greater than the heat transfer tube support plate installation interval at other positions. Alternatively, the configuration may be reduced.

  In the vicinity of the position upstream of the heat transfer tube group, the temperature difference between the liquid to be cooled and the low pressure refrigerant flowing inside the heat transfer tube group is large, so that the low pressure refrigerant boils violently and the specific volume of the boiling bubbles is higher than that of the high pressure refrigerant. Because of the large size, a larger vibration is generated than when a high-pressure refrigerant is used. For this reason, there is a concern that the heat transfer tube group is damaged due to resonance 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 position of the heat transfer tube group to be smaller than the installation interval of the heat transfer tube support plate in another position, in the vicinity of the upstream side of the heat transfer tube group Resonance can be suppressed and damage can be prevented.

  The turbo refrigeration apparatus according to the present invention is a turbo compressor that compresses low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG, a condenser that condenses the compressed low-pressure refrigerant, and evaporates the expanded low-pressure refrigerant. Any one of the evaporators described above is provided.

  According to the turbo refrigeration apparatus having the above-described configuration, when 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 according to the present invention and the turbo refrigeration apparatus including the evaporator, in the turbo refrigeration apparatus using the low-pressure refrigerant used at a maximum pressure of less than 0.2 MPaG, the heat transfer tube group in the evaporator As a result, it is possible to improve the heat transfer performance by preventing the dry-out of the liquid and to suppress a decrease in efficiency due to the liquid-phase low-pressure refrigerant being carried over to the turbo compressor side.

1 is an overall view of a turbo refrigeration apparatus 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 view of FIG. It is a longitudinal cross-sectional view of the evaporator which follows the III-III line of FIG. It is a longitudinal cross-sectional view of the evaporator which follows the IV-IV line of FIG. It is a side view of the evaporator which shows 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the evaporator which shows 3rd Embodiment of this invention. It is a VII arrow line view of FIG. (A), (b) is a longitudinal cross-sectional view of the refrigerant inlet which shows 4th Embodiment of this 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 apparatus according to an embodiment of the present invention. The turbo refrigeration apparatus 1 includes a turbo compressor 2 that compresses refrigerant, a condenser 3, a high-pressure expansion valve 4, an intermediate cooler 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 in a unit shape. 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 with 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 disposed at a relatively higher position 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 between the condenser 3 and the evaporator 7. The inverter unit 10 is installed on the top of 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 protrude significantly from the entire outline of the turbo refrigeration apparatus 1 in plan view.

  The turbo compressor 2 is of a known centrifugal turbine type that is rotationally driven by an electric motor 13, and is disposed above the evaporator 7 in a posture in which the axis thereof extends in a substantially horizontal direction. The electric motor 13 is driven by the inverter unit 10. As will be described later, the turbo compressor 2 compresses the gas-phase refrigerant supplied from the refrigerant outlet 23 of the evaporator 7 through the suction pipe 14. 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 top of the condenser 3 are connected by a discharge pipe 15, and the bottom of the condenser 3 and the bottom of the intermediate cooler 5 are connected by a refrigerant pipe 16. Further, the bottom of the intermediate cooler 5 and the evaporator 7 are connected by a refrigerant pipe 17, and the upper part of the intermediate cooler 5 and the middle stage of the turbo compressor 2 are connected by a refrigerant pipe 18. 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 a lower portion of the pressure vessel 21, and an upper portion of the pressure vessel 21. A refrigerant outlet 23, a heat transfer tube group 25 that passes through the inside of the pressure vessel 21 in the longitudinal axis direction, a refrigerant distribution plate 26, and a demister 27 are provided.

  The refrigerant inlet 22 and the refrigerant outlet 23 are respectively disposed 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 of the pressure vessel 21, The refrigerant outlet 23 is formed in a short pipe shape extending vertically upward from the upper part of the pressure vessel 21. As shown in FIG. 1, the refrigerant inlet 17 is connected to the refrigerant pipe 17 extending from the bottom of the intermediate cooler 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 thereon as independent rooms. In addition, a U-turn chamber 33 is provided as an independent room at the other inner end of the pressure vessel 21 (for example, the right end in FIG. 2). These chambers 31, 32, and 33 are all disposed 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 FIGS. 2, 3, and 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 to the other end (right end in FIG. 2) inside the pressure vessel 21. 25A and a return pipe group 25B that communicates with the forward pipe group 25A at the other end in the longitudinal axis inside the pressure vessel 21 and returns from the other end in the longitudinal axis inside the pressure vessel 21 to one end. Specifically, the outgoing pipe group 25A is disposed so as to connect the inlet chamber 31 and the lower part of the U-turn chamber 33, and the return pipe group 25B is provided between the outlet chamber 32 and the upper part of the U-turn chamber 33. It arrange | positions so that it may connect. In other words, the outward pipe group 25 </ b> A is arranged below the inside of the pressure vessel 21, and the return pipe group 25 </ b> B is arranged inside the pressure vessel 21.

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

  As shown in FIGS. 3 and 4, the forward tube group 25A and the return tube group 25B constituting the heat transfer tube group 25 each include a plurality of heat transfer tube bundles 25a in which a large number of heat transfer tubes are bundled in the horizontal direction (for example, four Each) arranged in parallel. A gap S1 extending in the vertical direction is formed between the heat transfer tube bundles 25a. Further, a gap S2 extending in the horizontal direction is formed between the forward tube group 25A and the backward tube group 25B.

  As shown in FIG. 2, individual heat transfer tubes constituting the heat transfer tube group 25 (25A, 25B) are fixed inside the pressure vessel 21 while being supported by a plurality of heat transfer tube support plates 37 inside the pressure vessel 21. ing. These heat transfer tube support plates 37 have a flat plate shape having a surface direction intersecting with the longitudinal axis direction of the pressure vessel 21. A plurality of these heat transfer tube support plates 37 are arranged 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 the through holes.

  The installation interval of the heat transfer tube support plate 37 along the longitudinal axis direction of the pressure vessel 21 is in the vicinity of the upstream position of the heat transfer tube group 25, that is, in the vicinity of 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 between the refrigerant inlet 22 and the heat transfer pipe group 25 (outward pipe group 25 </ b> A) inside the pressure vessel 21. The refrigerant distribution plate 26 is a plate-like member having a large number of refrigerant flow holes 26a.

  The area ratio of the refrigerant flow holes 26a per unit area in the refrigerant distribution plate 26 is in the range A1 corresponding to the vicinity of the upstream position of the heat transfer tube group 25 (25A), for example, in the middle of the heat transfer tube group 25. It is larger than the range A2 corresponding to the position of the section. In addition, the area ratio of the refrigerant circulation hole 26a is 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 middle portion in the longitudinal axis direction. 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 is not limited to this range. .

  As shown in FIGS. 3 and 4, the refrigerant distribution plate 26 is vertically below a gap S <b> 1 that extends between the plurality of heat transfer tube bundles 25 a constituting the heat transfer tube group 25 (25 </ b> A, 25 </ b> B). A refrigerant circulation hole 26a is arranged. That is, the refrigerant circulation holes 26a are arranged along the longitudinal direction of the gap S1 in plan view.

  As shown in FIGS. 2 to 4, the demister 27 is disposed inside the pressure vessel 21 between the refrigerant outlet 23 and the heat transfer tube group 25 (return tube group 25 </ b> B). The demister 27 is a member having high air permeability, for example, in which wires are entangled in a mesh shape, and performs gas-liquid separation of a low-pressure refrigerant. Not only a wire mesh but other porous substances may be used as long as air permeability is good.

  The demister 27 is attached so that the entire circumference of the demister 27 is in contact with the inner circumference of the pressure vessel 21, and the internal space of the pressure vessel 21 is divided into two vertically 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 interval 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 refrigeration apparatus 1 including the evaporator 7 configured as described above, the turbo compressor 2 is driven to rotate by the electric motor 13, and the gas-phase low-pressure refrigerant supplied from the evaporator 7 through the suction pipe 14 is supplied. The compressed low-pressure refrigerant is supplied 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 cooling water, whereby the heat of condensation is cooled and condensed. The low-pressure refrigerant that has become a liquid phase in the condenser 3 expands by passing through the high-pressure expansion valve 4 provided in the refrigerant pipe 16 that extends from the condenser 3, and becomes a gas-liquid mixed state. 5 and is temporarily stored here.

  Inside the intercooler 5, the gas-liquid mixed low-pressure refrigerant 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 a low-pressure expansion valve 6 provided in the refrigerant pipe 17 extending from the bottom of the intermediate cooler 5 to become a gas-liquid two-phase flow, and the evaporator 7. To be sent to. Further, the gas phase component of the low-pressure refrigerant separated by the intermediate cooler 5 is fed to the middle stage of the turbo compressor 2 via the refrigerant pipe 18 extending from the upper part of the intermediate cooler 5 and is compressed again.

  As shown in FIGS. 2 to 4, in the evaporator 7, low-temperature gas-liquid two-phase 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 passes through the refrigerant flow holes 26 a of the refrigerant distribution plate 26 and flows upward. 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 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. Thereby, the water which passes the inside of the heat exchanger tube group 25 is cooled, and becomes cold water. This cold water is used as a cooling / heating medium for air conditioning, industrial cooling water, or the like.

  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) travels through the pressure vessel 21 toward the refrigerant outlet 23, 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 unvaporized liquid-phase refrigerant ejected from the low-pressure refrigerant pool tend to come out from the refrigerant outlet 23 along with the fast flow of the vaporized refrigerant, and there is a possibility that carry-over occurs.

  However, since these droplets are captured and separated by the porous demister 27 and fall into the low-pressure refrigerant pool due to gravity, carry-over is prevented. The vaporized refrigerant thus separated from the gas and liquid exits from the refrigerant outlet 23 and is again sucked and compressed into the turbo compressor 2 through the suction pipe 14, and this refrigeration cycle is repeated thereafter.

  In the evaporator 7, the area ratio of the refrigerant circulation 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 such that the heat transfer tube group. The range A1 corresponding to the vicinity of the position on the upstream side of 25 (25A) is made larger than the other range A2.

  For this reason, the low-pressure refrigerant introduced into the pressure vessel 21 from the refrigerant inlet 22 is distributed in a relatively large amount near the upstream position of the heat transfer tube group 25 (25A). A relatively small amount of low-pressure refrigerant is distributed to other positions. Thereby, 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 upstream of the heat transfer tube group 25 (25A) in the evaporator 21, the low-pressure refrigerant boils violently due to a large temperature difference from the water flowing in the heat transfer tube group 25 (25A). However, since a relatively large amount of low-pressure refrigerant is distributed to this position as described above, the vicinity of the upstream position of the heat transfer tube group 25 (25A) is surrounded by boiling bubbles of low-pressure refrigerant. Thus, the heat transfer tube group 25 (25A, 25B) can be maintained immersed in the refrigerant two-phase liquid. For this reason, the to-be-cooled liquid and the low-pressure refrigerant flowing inside the heat transfer tube group 25 (25A, 25B) can be favorably exchanged, and the heat transfer performance of the heat transfer tube group 25 (25A, 25B) can be improved. it can.

  As described above, since the floss level of the low-pressure refrigerant pool does not rise at both ends in the longitudinal axis direction of the pressure vessel 21 in the longitudinal axis direction intermediate portion, the longitudinal axis direction intermediate portion of the pressure vessel 21 as in the present embodiment. By providing the refrigerant outlet 23 leading to the suction pipe 14 of the turbo compressor 2, it is possible to effectively prevent the liquid-phase refrigerant from being carried over to the turbo compressor 2 side along the flow of the vaporized refrigerant, A reduction in efficiency of the turbo compressor 2 can be suppressed.

  Further, the evaporator 7 is provided with the refrigerant inlet 22 in the intermediate portion in the longitudinal axis direction of the pressure vessel 21, and the area ratio of the refrigerant flow holes 26 a in the refrigerant distribution plate 26 is equal to both longitudinal end portions of the refrigerant distribution plate 26. In the ranges A1 and A3, the range A2 of the intermediate portion in the longitudinal axis direction is made larger.

  For this reason, a large amount of low-pressure refrigerant introduced into the pressure vessel 21 from the refrigerant inlet 22 provided in the intermediate portion in the longitudinal axis of the pressure vessel 21 is supplied to both ends in the longitudinal axis inside the pressure vessel 21, and the refrigerant inlet 22. A relatively small amount is supplied to an intermediate portion in the longitudinal axis direction of the pressure vessel 21 which is directly above the upper portion. For this reason, the liquid level height (floss level) of the low-pressure refrigerant pool inside the pressure vessel 21 is made uniform so that the heat flowing between the water flowing in the heat transfer tube group 25 (25A, 25B) and the low-pressure refrigerant is excellent. The heat transfer performance of the heat tube group 25 (25A, 25B) can be enhanced.

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

  If the heat transfer tube group 25 is configured in this manner, the forward 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 at the lower part of the pressure vessel 21, and flows in the heat transfer tube. A return pipe group 25 </ b> B in which the temperature difference with water is small and the boiling of the low-pressure refrigerant is gentle is arranged in the upper part of the pressure vessel 21.

  For this reason, intense boiling of the low-pressure refrigerant is performed below (in the deep part) the liquid level of the low-pressure refrigerant pool in the pressure vessel 21, and the liquid-phase refrigerant is less likely to scatter on the liquid level 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 along with 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 gap S1 extending in the vertical direction is formed between these heat transfer tube bundles 25a. Yes.

  The vertical gap S1 between the plurality of heat transfer tube bundles 25a becomes a passage for boiling bubbles of the low-pressure refrigerant boiled by heat exchange with the heat transfer tube group 25 (25A, 25B). Thereby, the boiling bubbles can easily float on the liquid level 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 dry out under the refrigerant liquid level, and to improve the heat transfer performance of the heat transfer tube group 25 (25A, 25B).

  In addition, since the refrigerant flow hole 26a drilled in the refrigerant distribution plate 26 is disposed vertically below the gap S1, it passes through the refrigerant flow hole 26a of the refrigerant distribution plate 26 and is discharged upward. The flow of the low-pressure refrigerant passes through the gap 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 enhanced.

  When a low-pressure refrigerant is used as in the turbo refrigeration apparatus 1, the gas flow rate inside the pressure vessel 21 of the evaporator 7 is increased due to the characteristics of the low-pressure refrigerant that has a larger specific deposition than the high-pressure refrigerant. For this reason, the distance until the droplets of the liquid-phase refrigerant ejected from the low-pressure refrigerant pool inside the pressure vessel 21 are separated from the gas-phase refrigerant by its own weight becomes relatively long. For this reason, if the demister 27 is installed at a position higher than the position where the droplets separate by their own weight, the distance from the refrigerant liquid surface to the demister 27 becomes longer, and the shell diameter of the pressure vessel 21 becomes larger.

In this evaporator 7, the demister 27 is disposed immediately above the heat transfer tube group 25, whereby the amount of liquid droplets ejected from the low-pressure refrigerant pool is reduced by the demister 27, and the low-pressure refrigerant liquid droplets exit from the refrigerant outlet 23. (Carry over) is suppressed.
Furthermore, by disposing the demister 27 directly above the heat transfer tube group 25, the space height on the demister 27 is relatively increased, and the evaporation mist of the low-pressure refrigerant is promoted to be a droplet having a large diameter, By reducing the distance at which the droplets separate by their own weight, the carry-over of the low-pressure refrigerant can also be suppressed in this respect.

  Further, in the 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 low-pressure refrigerant gas flow inside the pressure vessel 21 passes through the demister 27, and the flow resistance of the gas flow increases. For this reason, 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.

  Moreover, in this evaporator 7, the installation space | interval L1 in the position vicinity of the upstream of the heat exchanger tube group 25 of the some heat exchanger tube support plate 37 which supports each heat exchanger tube of the heat exchanger tube group 25 is other position. Is smaller than the installation interval L2.

  In the vicinity of the upstream side position of the heat transfer tube group 25, as described above, the temperature difference between the water flowing in the heat transfer tube group 25 and the low pressure refrigerant is large, so the low pressure refrigerant boils violently, and the specific volume of the boiling bubbles is Since it is larger than the high-pressure refrigerant, a larger vibration is generated than when the high-pressure refrigerant is used. For this reason, there is a concern that the heat transfer tube group 25 may be damaged due to resonance with the vibration of the boiling bubbles.

  As described above, by setting the installation interval L1 of the heat transfer tube support plate 37 in the vicinity of the upstream position of the heat transfer tube group 25 to be smaller than the installation interval L2 in other positions, in the vicinity of the upstream side of the heat transfer tube group 25. Installation rigidity can be increased, and resonance can be suppressed to prevent breakage.

[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 in a dispersed manner along the longitudinal axis direction of the pressure vessel 21. However, other configurations are the same. For this reason, the same code | symbol is provided to each part of the same structure, and description is abbreviate | omitted.

  In the present embodiment, for example, the two refrigerant inlets 22 </ b> A are provided so as to be distributed 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 locations. These refrigerant inlets 22 </ b> A are formed in a short pipe shape that extends horizontally and tangentially from the bottom of the pressure vessel 21, similar to the refrigerant inlet 22 of the first embodiment. The diameter of each refrigerant inlet 22A is made smaller than the diameter of the refrigerant inlet 22 of the first embodiment.

  As described above, since the specific volume of the low-pressure refrigerant is larger than that of the high-pressure refrigerant, the volumetric flow rate flowing into the evaporator 7A is large and the dynamic pressure is high, but the refrigerant distribution holes 26a of the refrigerant distribution plate 26 are made smaller accordingly. When the pressure loss is increased by, for example, increasing the speed at which the low-pressure refrigerant is ejected from the refrigerant circulation hole 26a, the heat transfer tube group 25 is vibrated or damaged.

  Like this evaporator 7A, two or three or more refrigerant inlets 22A are provided separated along the longitudinal axis direction of the pressure vessel 21, thereby providing a single refrigerant inlet 22 as in the first embodiment. Compared with the case where it provides, the inflow speed of the low-pressure refrigerant into the pressure vessel 21 can be reduced. For this reason, the diameter of the refrigerant | coolant circulation hole 26a of the refrigerant | coolant distribution board 26 can be enlarged, and the speed at which a low-pressure refrigerant | coolant ejects from the refrigerant | coolant circulation hole 26a can be reduced by this.

  Thus, vibration and breakage of the heat transfer tube group 25 are prevented, and the liquid-phase low-pressure refrigerant is suppressed from being carried over to the turbo compressor 2 side due to local jetting or the like. The reduction in efficiency can be avoided.

[Third Embodiment]
6 is a longitudinal sectional view of an evaporator showing a third embodiment of the present invention, and FIG. 7 is a view taken along arrow VII in FIG.
In the evaporator 7B, the flow path cross-sectional area from the outer opening 22a of the refrigerant inlet 22 provided at the bottom of the pressure vessel 21 to the pressure vessel 21 increases from the outer opening 22a toward the pressure vessel 21. Yes. Specifically, an expansion channel 22 b is provided between the outer opening 22 a and the pressure vessel 21. Since the other configuration is the same as that of the evaporator 7 of the first embodiment shown in FIG. 3, the same reference numerals are given to the parts having the same configuration and the description thereof is omitted.

  The extended flow path 22b is formed in, for example, a box shape, and the flow path cross-sectional area thereof is larger than the flow path cross-sectional area of the refrigerant inlet 22. For example, the channel cross-sectional area of the expansion channel 22 b is set to about 2 to 5 times the channel cross-sectional area of the refrigerant inlet 22. The shape of the extended flow path 22b is not limited to a box shape, and may be other shapes as long as the flow path cross-sectional area is larger than the outer opening 22a of the refrigerant inlet 22. For example, the expansion channel 22b may be formed in 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 without providing the expansion channel 22b.

In this way, by increasing the cross-sectional area of the flow path from the outer opening 22 a of the refrigerant inlet 22 to the pressure vessel 21 toward the pressure vessel 21, the flow rate of the low-pressure refrigerant flowing through the refrigerant inlet 22 increases toward the pressure vessel 21. descend.
Therefore, the speed at which the low-pressure refrigerant is ejected from the refrigerant flow hole 26a of the refrigerant distribution plate 26 is reduced to prevent the heat transfer tube group 25 from being vibrated or damaged, and the liquid-phase low-pressure refrigerant is locally ejected. Thus, carry over to the turbo compressor 2 side can be suppressed, and a decrease in efficiency of the turbo compressor 2 can be avoided.

[Fourth Embodiment]
8 (a) and 8 (b) are longitudinal sectional views of an evaporator showing a fourth embodiment of the present invention.
This evaporator 7C is different 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 in the pipe of the refrigerant inlet 22, and other configurations. Are the same.

  As the flow velocity attenuating member, as shown in FIG. 8 (a), a porous plate (punching plate or the like) 22c is installed in the pipe of the refrigerant inlet 22, or as shown in FIG. It may be possible to install a plurality of baffle plates 22d in a maze shape. As long as the flow rate of the low-pressure refrigerant in the pipe of the refrigerant inlet 22 can be attenuated, other than these 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 into the pressure vessel 21 from the refrigerant inlet 22 is reduced.
Therefore, the speed at which the low-pressure refrigerant is ejected from the refrigerant flow hole 26a of the refrigerant distribution plate 26 is reduced to prevent the heat transfer tube group 25 from being vibrated or damaged, and the liquid-phase low-pressure refrigerant is locally ejected. Thus, carry over to the turbo compressor 2 side can be suppressed, and a decrease in efficiency of the turbo compressor 2 can be avoided.

  As described above, according to the evaporators 7, 7A, 7B, and 7C according to the present embodiment and the turbo refrigeration apparatus 1 including these evaporators, the low-pressure refrigerant that is used at a maximum pressure of less than 0.2 MPaG. In the turbo refrigeration apparatus 1 using the above, the heat transfer performance is improved by preventing the heat transfer tube 25 group in the evaporator from being dried out, and the liquid-phase low-pressure refrigerant is carried over to the turbo compressor 2 side. A decrease in efficiency can be suppressed.

  It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and can be appropriately changed or improved. Embodiments with such changes and improvements are also included in the scope of the right of the present invention. And For example, the above first to fourth embodiments may be combined.

DESCRIPTION OF SYMBOLS 1 Turbo refrigeration apparatus 2 Turbo compressor 3 Condenser 7 Evaporator 21 Pressure vessel 22 Refrigerant inlet 22a Outer opening 22b of refrigerant inlet Expansion flow path 22c Perforated plate (flow velocity attenuation member)
22d baffle plate (flow velocity damping member)
23 Refrigerant outlet 25 Heat transfer tube group 25A Outbound tube group 25B Return tube group 25a Heat transfer tube bundle 26 Refrigerant distribution plate 26a Refrigerant flow hole 27 Demister 37 Heat transfer tube support plate A1 Range corresponding to the upstream position of the heat transfer tube group (refrigerant The range of the end of the distribution plate in the longitudinal direction)
A2 Range corresponding to the other position of the heat transfer tube group (range in the longitudinal direction intermediate portion of the refrigerant distribution plate)
A3 Range L1, L2 of the end portion in the longitudinal direction of the refrigerant distribution plate Installation interval S1 of the heat transfer tube support plate

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 a lower portion of the pressure vessel;
A refrigerant outlet provided at an upper portion 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 exchanges heat between the liquid to be cooled and the low-pressure refrigerant;
A plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant circulation hole;
The area ratio of the refrigerant flow holes per unit area in the refrigerant distribution plate is:
The evaporator characterized by being larger in the range corresponding to the vicinity of the upstream position of the heat transfer tube group than the other ranges. The refrigerant inlet is provided at a middle portion in the longitudinal axis direction of the pressure vessel,
The evaporator according to claim 1, wherein the area ratio of the refrigerant circulation holes in the refrigerant distribution plate is larger in the range of the longitudinal direction end portion of the refrigerant distribution plate than in the range of the intermediate portion in the longitudinal axis direction. 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 a lower portion of the pressure vessel;
A refrigerant outlet provided at an upper portion 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 exchanges heat between the liquid to be cooled and the low-pressure refrigerant;
A plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant circulation hole;
The evaporator characterized in that a plurality of the refrigerant inlets are distributed along the longitudinal axis direction of the pressure vessel. 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 a lower portion of the pressure vessel;
A refrigerant outlet provided at an upper portion 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 exchanges heat between the liquid to be cooled and the low-pressure refrigerant;
A plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant circulation hole;
An evaporator, wherein a cross-sectional area of a flow path from an outer opening of the refrigerant inlet to the pressure vessel increases from the outer opening toward the pressure vessel. 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 a lower portion of the pressure vessel;
A refrigerant outlet provided at an upper portion 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 exchanges heat between the liquid to be cooled and the low-pressure refrigerant;
A plate-like refrigerant distribution plate installed between the refrigerant inlet and the heat transfer tube group inside the pressure vessel, and having a refrigerant circulation hole;
The evaporator is characterized in that the refrigerant inlet has a tubular shape connected to the pressure vessel, and a flow rate attenuating member for attenuating the flow rate of the low-pressure refrigerant is provided in the tube. The heat transfer tube group is:
A forward tube group extending from one end to the other end in the longitudinal direction inside the pressure vessel;
A return pipe group communicating with the forward pipe group at the other longitudinal axis inside the pressure vessel and returning from the other longitudinal axis inside the pressure vessel to the one end; and
The evaporator according to any one of claims 1 to 5, wherein the forward tube group is disposed below and the return tube group is disposed above in the pressure vessel.   7. The heat transfer tube group according to claim 1, wherein 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 extending in the vertical direction is formed between the heat transfer tube bundles. Evaporator.   The evaporator according to claim 7, wherein the refrigerant circulation hole drilled in the refrigerant distribution plate is arranged vertically below the gap.   The demister which is located between the refrigerant outlet and the heat transfer tube group inside the pressure vessel and performs gas-liquid separation of the low-pressure refrigerant is disposed immediately above the heat transfer tube group. The evaporator in any one of.   The evaporator according to claim 9, wherein the demister is provided so that an entire circumference thereof is in contact with an inner circumference of the pressure vessel.   Each of the heat transfer tubes constituting the heat transfer tube group has a plurality of heat transfer tube support plates that have a surface direction intersecting with the longitudinal axis direction of the pressure vessel and are spaced from each other in the longitudinal axis direction of the pressure vessel. The installation interval of the heat transfer tube support plate in the vicinity of the upstream position of the heat transfer tube group is smaller than the installation interval of the heat transfer tube support plate at another position. The evaporator according to crab. 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 refrigeration apparatus comprising:

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