CN210004632U - Evaporator for compression refrigerator and compression refrigerator provided with same - Google Patents

Abstract

The evaporator for a compression refrigerator according to the present invention is provided with a tank (30), an evaporation heat transfer tube group (32) disposed in the tank (30), an overheating heat transfer tube group (33) disposed in the tank (30) at a position away from the evaporation heat transfer tube group (32), a refrigerant distribution unit (40) disposed above the evaporation heat transfer tube group (32) and supplying a refrigerant liquid to the evaporation heat transfer tube group (32), and a baffle (60) for preventing refrigerant vapor generated by the partial flash evaporation of the refrigerant liquid and refrigerant vapor generated by the contact between the evaporation heat transfer tube group (32) and the refrigerant liquid from flowing upward, and the baffle (60) is disposed above the evaporation heat transfer tube group (32).

Description

Evaporator for compression refrigerator and compression refrigerator provided with same

Technical Field

The present invention relates to a compression type refrigerator such as a screw refrigerator and a centrifugal refrigerator, and more particularly to an evaporator connected to a suction port of a compressor.

Background

A compression type refrigerator used in a refrigerating and air-conditioning apparatus or the like is configured as a closed system in which a refrigerant is sealed. Compression refrigerators are generally configured as: an evaporator that generates a cooling effect by absorbing heat from a fluid to be cooled and evaporates a refrigerant by a refrigerant pipe, a compressor that compresses the refrigerant vapor evaporated by the evaporator to generate a high-pressure refrigerant vapor, a condenser that cools and condenses the high-pressure refrigerant vapor by a cooling fluid, and an expansion valve that decompresses and expands the condensed refrigerant are connected to each other.

The expansion valve is controlled based on the degree of superheat (saturation temperature corresponding to the temperature of refrigerant vapor at the inlet of the compressor-the pressure at the inlet of the compressor). As the circulation amount of the refrigerant increases, the compressor may be damaged by the suction of refrigerant liquid, and therefore, in order to prevent the suction of refrigerant liquid from the outlet of the evaporator to the compressor, it is necessary to control the expansion valve so as to maintain the degree of superheat at (for example, 3 to 5 ℃).

Patent document 1: japanese laid-open patent publication No. 6-213515

The refrigerant liquid flowing into the evaporator contacts portions of the heat transfer tube set and evaporates to become refrigerant vapor.

However, if the circulation amount of the refrigerant liquid increases in accordance with an increase in the cooling load, the refrigerant liquid may be scattered and the liquid refrigerant may be sucked into the compressor. To avoid this, it is necessary to add a heat transfer tube group, resulting in an increase in the evaporator itself. Further, when the circulation amount of the refrigerant liquid is reduced, the area of the heat transfer pipe that contributes neither to evaporation of the refrigerant nor to overheating increases, and the heat exchange efficiency between the refrigerant and the fluid to be cooled decreases.

SUMMERY OF THE UTILITY MODEL

Therefore, the present invention provides an evaporator capable of effectively using a heat transfer tube group for evaporation and superheating of a refrigerant. In addition, the utility model provides a compression refrigerator that possesses foretell evaporimeter.

Among , types of evaporators which are liquid film evaporators for use in compression refrigerators are provided with a tank, an evaporation heat transfer tube group disposed in the tank, a superheating heat transfer tube group disposed in the tank at a position apart from the evaporation heat transfer tube group, a refrigerant distribution unit disposed above the evaporation heat transfer tube group and configured to supply a refrigerant liquid to the evaporation heat transfer tube group, and a baffle plate disposed above the evaporation heat transfer tube group and configured to prevent upward flow of refrigerant vapor generated by vaporization of portions of the refrigerant liquid and refrigerant vapor generated by contact between the evaporation heat transfer tube group and the refrigerant liquid.

According to the utility model discloses, overheated with heat transfer nest of tubes and evaporation with heat transfer nest of tubes set up respectively. With this arrangement, the evaporation heat transfer tube group itself can be reduced in size, and the refrigerant liquid can be distributed not only to the upper portion of the evaporation heat transfer tube group but also to the side portions and the lower portion of the evaporation heat transfer tube group. Therefore, the entire evaporation heat transfer tube group can contribute to evaporation of the refrigerant liquid. In addition, the heat transfer tubes constituting the evaporation heat transfer tube group are covered with the refrigerant liquid film, so that the dry state of the heat transfer tubes can be avoided. Therefore, the lubricant oil contained in the refrigerant liquid can be prevented from adhering to the surface of the heat transfer pipe, and as a result, the heat exchange efficiency between the refrigerant liquid and the fluid to be cooled (for example, cold water) flowing in the heat transfer pipe can be improved.

The baffle can guide the refrigerant vapor generated by flashing part of the refrigerant liquid and the refrigerant vapor generated by the contact between the evaporation heat transfer tube group and the refrigerant liquid to the superheating heat transfer tube group by shifting the flow of the refrigerant vapor in the lateral direction.

In the modes, the baffle and the refrigerant distribution unit are -body structures.

According to the present invention, since the baffle plate and the refrigerant dispersing unit are not required to be disposed in the tank body, the evaporator can be easily assembled.

In , the superheating heat transfer tube group is the portion of the heat transfer tube group of the -th flow path for the cooled fluid to flow.

The heat transfer tube group for superheating can efficiently superheat the refrigerant vapor, and can evaporate the mist refrigerant contained in the refrigerant vapor, because the fluid to be cooled flowing through the heat transfer tube group in the th flow has a relatively high temperature.

In the modes, the evaporator further includes a header cover that covers the tube plate of the tank, a cooled fluid inlet port that is connected to the header cover, and a partition plate that partitions a fluid chamber formed between the tube plate and the header cover into a th fluid chamber and a second fluid chamber, and the cooled fluid inlet port and the superheating heat transfer tube group are in communication with the th fluid chamber.

In the modes, the outer surface area per unit length of the heat transfer tubes constituting the superheating heat transfer tube group is larger than the outer surface area per unit length of the heat transfer tubes constituting the evaporation heat transfer tube group.

According to the present invention, the heat transfer tube constituting the group of superheating heat transfer tubes is a heat transfer tube having a large outer surface area, such as a heat transfer tube having a large number of fins. Such a heat transfer tube can promote heat transfer of the refrigerant vapor outside the tube and heat exchange between the refrigerant vapor outside the tube and the fluid to be cooled inside the tube, and therefore the number of heat transfer tubes constituting the superheating heat transfer tube group can be reduced.

In the modes, the superheating heat transfer tube group is disposed beside the evaporation heat transfer tube group.

In the aspects, the evaporator further includes a refrigerant vapor guide plate disposed between the evaporation heat transfer tube group and the superheating heat transfer tube group, and the refrigerant vapor guide plate extends downward from the baffle plate.

The evaporation heat transfer tube group is connected to the suction port of the compressor, and therefore, the internal pressure of the tank is low, the refrigerant liquid is sent from the condenser to the evaporator, and is dispersed from the refrigerant dispersion means, at this time, portions of the refrigerant liquid are instantaneously evaporated (flashed) to form a refrigerant jet flow, the refrigerant vapor guide plate can prevent the refrigerant jet flow from scattering, the refrigerant vapor guide plate guides the vapor flow of the refrigerant downward to the evaporation heat transfer tube group, and the vapor flow of the refrigerant toward the downward removes portions of the refrigerant liquid from the surface of the upper heat transfer tubes constituting the evaporation heat transfer tube group, thereby reducing the film thickness of the refrigerant liquid on the upper heat transfer tubes.

The refrigerant vapor present in the gaps in the evaporation heat transfer tube group is guided downward by the refrigerant vapor guide plate, and then flows from the evaporation heat transfer tube group to the side surface. The refrigerant vapor flows through a space existing between the evaporation heat transfer tube group and the superheating heat transfer tube group before contacting the superheating heat transfer tube group. At this time, the flow velocity of the refrigerant vapor decreases, and therefore droplets of the refrigerant contained in the refrigerant vapor fall by their own weight. Therefore, the droplets of the refrigerant present in the refrigerant vapor are greatly reduced, and the refrigerant vapor in a substantially saturated state contacts the superheating heat transfer tube group. As a result, the superheating effect in the superheating heat transfer tube group is improved.

In the modes, the lower end of the refrigerant vapor guide plate is located at a position lower than the inner lower end of the superheating heat transfer tube group.

According to the present invention, almost all of the refrigerant vapor passing through the evaporation heat transfer tube group can be guided to the superheating heat transfer tube group.

In the modes, the evaporator further includes limiting walls disposed on both sides of the refrigerant distribution unit, and the limiting walls are disposed above both edges of the evaporation heat transfer tube group.

The restricting wall can prevent scattering of the refrigerant liquid discharged from the refrigerant spreading unit. The refrigerant liquid in contact with the limiting wall drops from the limiting wall and comes into contact with the heat transfer tubes constituting both edges of the evaporation heat transfer tube group. Therefore, the refrigerant liquid is supplied over the entire width of the evaporation heat transfer tube group, and the heat exchange efficiency between the cooling target fluid flowing through the evaporation heat transfer tube group and the refrigerant liquid can be improved.

Among the systems, types of compression refrigerators are provided with the evaporator that evaporates a refrigerant liquid to generate a refrigerant vapor, a compressor that compresses the refrigerant vapor, a condenser that condenses the compressed refrigerant vapor to generate the refrigerant liquid, and an expansion valve disposed between the condenser and the evaporator.

In the aspects, the compression refrigerator further includes an inlet temperature measuring device that measures an inlet temperature of the fluid to be cooled flowing into the superheating heat transfer tube group, an outlet temperature measuring device that measures an outlet temperature of the fluid to be cooled flowing out of the superheating heat transfer tube group, and a valve control unit that controls an opening degree of the expansion valve based on a difference between the inlet temperature and the outlet temperature.

When the liquid refrigerant in the refrigerant vapor evaporates by contact with the superheating heat transfer tube group, the difference between the inlet temperature and the outlet temperature of the fluid to be cooled rapidly changes. That is, the change in the difference between the inlet temperature and the outlet temperature of the fluid to be cooled reflects the amount of liquid refrigerant in the refrigerant vapor that contacts the superheating heat transfer tube group. Therefore, the valve control unit can precisely control the opening degree of the expansion valve, that is, the degree of superheat, based on the difference between the inlet temperature and the outlet temperature of the fluid to be cooled. In addition, according to the utility model discloses, need not to set up the liquid level sensor in the evaporimeter, consequently can control the expansion valve with low price.

According to the utility model discloses, can reduce evaporation and use heat transfer nest of tubes itself, not only can be to evaporation and use the upper portion of heat transfer nest of tubes, also can be to evaporation with the lateral part and the lower part of heat transfer nest of tubes spread refrigerant liquid. Therefore, the entire evaporation heat transfer tube group can contribute to evaporation of the refrigerant liquid. In addition, the heat transfer tubes constituting the evaporation heat transfer tube group are covered with the refrigerant liquid film, and the dry state of the heat transfer tubes can be avoided. Therefore, it is possible to prevent the lubricant oil contained in the refrigerant liquid (lubricant oil used in the compressor) from adhering to the surface of the heat transfer pipe, and as a result, it is possible to improve the heat exchange efficiency between the refrigerant liquid and the fluid to be cooled (for example, cold water) flowing in the heat transfer pipe. The baffle can guide the flow of the refrigerant vapor generated by the contact between the evaporation heat transfer tube group and the refrigerant liquid to the superheating heat transfer tube group while shifting the flow in the lateral direction. The refrigerant vapor is superheated by the superheating heat transfer tube group, and the mist-like refrigerant contained in the refrigerant vapor evaporates. Therefore, the suction of the mist refrigerant into the compressor can be prevented.

Drawings

Fig. 1 is a schematic diagram showing embodiments of a centrifugal refrigerator.

Fig. 2 is a side view of embodiments of the evaporator.

Fig. 3 is a sectional view taken along line a-a of fig. 2.

Fig. 4 is a sectional view taken along line B-B of fig. 2.

Fig. 5 is an enlarged view showing the refrigerant spreading unit, the refrigerant vapor guide plate, and the restricting wall.

Fig. 6 is an enlarged view of embodiments showing the arrangement of the refrigerant distribution unit, the baffle plate, and the restricting wall.

Fig. 7 is a view seen from the direction indicated by the arrow C of fig. 6.

Fig. 8 is an enlarged view showing another embodiment of the arrangement of the refrigerant distribution unit, the baffle plate, and the restricting wall.

Fig. 9 is a view seen from the direction indicated by the arrow D of fig. 8.

FIG. 10 is a cross-sectional view of other embodiments of evaporators.

Fig. 11 is a sectional view of a water chamber cover of the evaporator of the embodiment shown in fig. 10.

Fig. 12 is a cross-sectional view of yet another embodiment of an evaporator .

Fig. 13 is a sectional view of a water chamber cover of the evaporator of the embodiment shown in fig. 12.

Fig. 14 is a cross-sectional view of yet another embodiment of an evaporator .

Fig. 15 is a sectional view of a water chamber cover of the evaporator of the embodiment shown in fig. 14.

The reference numbers indicate 1 … compressor, 2 … evaporator, 3 … condenser, 4A, 4B, 4C, 4D, 4E … refrigerant tubing, 5 … refrigerant liquid inlet, 6 … refrigerant vapor outlet, 9 … economizer, 10 … valve control, 11 … stage impeller, 12 … second stage impeller, 13 … motor, 16 … guide vane, 17 … intermediate suction inlet, 20 … bypass line, 21, 22, 25 … expansion valve, 30 … tank, 31 … heat transfer tube bank, 31-1 … first … flow heat transfer tube bank, 31-2 … second flow heat transfer tube bank, 32 … evaporation heat transfer tube bank, 32a … evaporation heat transfer tube bank, 32B … second evaporation heat transfer tube bank, 33 … evaporation heat transfer tube bank, 40 … dispersion refrigerant unit, 42 …, … cover … tube bank, … evaporation heat transfer tube bank, 32a … evaporation heat transfer tube bank, 32B … second evaporation heat transfer tube bank, 33 … evaporation heat transfer tube bank …, … evaporation heat transfer chamber …, fluid inlet, cooling fluid inlet, 3, cooling fluid inlet, 3 fluid inlet fluid channel fluid inlet, 3S 5972 fluid inlet fluid.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a schematic diagram showing embodiments of a centrifugal refrigerator, which is examples of a compression-type refrigerator, and as shown in fig. 1, the centrifugal refrigerator includes an evaporator 2 that evaporates a refrigerant liquid to generate a refrigerant vapor, a compressor 1 that compresses the refrigerant vapor, and a condenser 3 that condenses the compressed refrigerant vapor to generate a refrigerant liquid, the evaporator 2 has a refrigerant liquid inlet 5 and a refrigerant vapor outlet 6, a suction port of the compressor 1 is connected to the refrigerant vapor outlet 6 of the evaporator 2 via a refrigerant pipe 4A, and a discharge port of the compressor 1 is connected to the condenser 3 via a refrigerant pipe 4B.

The centrifugal chiller further includes an economizer 9 disposed between the condenser 3 and the evaporator 2, the condenser 3 is connected to the economizer 9 through a refrigerant pipe 4C, the economizer 9 is connected to the evaporator 2 through a refrigerant pipe 4D, the economizer 9 is connected to the compressor 1 through a refrigerant pipe 4E, the economizer 9 is an intercooler disposed between the condenser 3 and the evaporator 2, an expansion valve 21 is attached to the refrigerant pipe 4C extending from the condenser 3 to the economizer 9, an expansion valve 22 is attached to the refrigerant pipe 4D extending from the economizer 9 to the evaporator 2, the expansion valves 21, 22 are configured to be adjustable in opening degree, for example, by an electric valve with variable opening degree, the expansion valves 21, 22 may be configured by the expansion valves and orifice plates disposed in parallel, respectively, and of the expansion valves 21, 22 may be adjustable in flow rate, and may be fixed orifice plates.

In the present embodiment, the compressor 1 is configured by a multistage centrifugal compressor, more specifically, the compressor 1 is configured by a two-stage centrifugal compressor, and includes an th-stage impeller 11, a second-stage impeller 12, and a motor 13 for rotating the impellers 11, 12.

Guide vanes 16 for adjusting the suction flow rate of refrigerant vapor to the impellers 11, 12 are disposed at the suction port of the compressor 1, the guide vanes 16 are positioned on the suction side of the th-stage impeller 11, the guide vanes 16 are disposed in a radial shape, and the opening degree of the guide vanes 16 is changed by rotating each guide vane 16 by a predetermined angle in synchronization with each other about the axial center thereof, the refrigerant vapor sent from the evaporator 2 passes through the guide vanes 16, is then sequentially pressurized by the rotating impellers 11, 12, and the pressurized refrigerant vapor is sent to the condenser 3 through the refrigerant pipe 4B.

The centrifugal chiller includes a bypass line 20 for guiding the refrigerant vapor from the condenser 3 to the evaporator 2, and an expansion valve (hot gas dual-purpose bypass valve) 25 for opening and closing the bypass line 20, the bypass line 20 extends while bypassing the economizer 9, an end of the bypass line 20 is connected to the refrigerant pipe 4C, another end of the bypass line 20 is connected to the refrigerant pipe 4d, and the expansion valve 25 is configured to be adjustable in opening degree, and is constituted by, for example, an electrically operated valve with a variable opening degree.

The expansion valves 21, 22, 25 are electrically connected to the valve control unit 10, and the operations of the expansion valves 21, 22, 25 are controlled by the valve control unit 10. In normal operation, the expansion valve 25 is closed. When the valve control unit 10 opens the expansion valve 25, the refrigerant vapor compressed by the compressor 1 or the refrigerant liquid in the condenser 3 bypasses the economizer 9 and is sent from the condenser 3 to the evaporator 2 through the bypass line 20.

The compressor 1 compresses the refrigerant vapor evaporated in the evaporator 2 to generate high-pressure refrigerant vapor, and the condenser 3 cools and condenses the high-pressure refrigerant vapor with the cooling fluid (e.g., cooling water) to generate refrigerant liquid, the refrigerant liquid passes through the expansion valve 21 to be decompressed, the refrigerant vapor present in the decompressed refrigerant liquid is separated by the economizer 9 and sent to the intermediate suction port 17 provided between the -th stage impeller 11 and the second-stage impeller 12 of the compressor 1, the refrigerant liquid passing through the economizer 9 is decompressed by the expansion valve 22 and then sent to the evaporator 2 through the refrigerant pipe 4D, and thus, the centrifugal refrigerator is configured as a closed system in which the refrigerant is sealed, and the refrigerating effect is exhibited in some cases.

The centrifugal refrigerator further includes: a temperature sensor 81 serving as an inlet temperature measuring device for measuring the inlet temperature of the cooling target fluid flowing into the superheating heat transfer tube group (described later) of the evaporator 2, and a temperature sensor 82 serving as an outlet temperature measuring device for measuring the outlet temperature of the cooling target fluid flowing out of the superheating heat transfer tube group. The temperature sensors 81 and 82 are electrically connected to the valve control unit 10, and output values of the temperature sensors 81 and 82 (i.e., measured values of the inlet temperature and the outlet temperature of the cooling target fluid) are sent to the valve control unit 10.

Fig. 2 is a side view of embodiments of the evaporator 2, the evaporator 2 includes, as shown in fig. 2, a tank 30, a heat transfer tube group 31 disposed in the tank 30, and a refrigerant distribution unit 40, the refrigerant distribution unit 40 includes a refrigerant liquid inlet 5, the refrigerant liquid inlet 5 being connected to a condenser 3 and an economizer 9 via refrigerant pipes 4C and 4D, and a refrigerant vapor outlet 6 is provided at the top of the tank 30, in the present embodiment, the heat transfer tube group 31 disposed in the tank 30 includes a heat transfer tube group 31-1 of a th flow path and a heat transfer tube group 31-2 of a second flow path, and in fig. 2, these heat transfer tube groups 31-1 and 31-2 are schematically depicted, and the heat transfer tube group 31-1 of a th flow path includes a evaporation heat transfer tube group 32A for evaporating a refrigerant liquid to generate refrigerant vapor, and a superheating heat transfer tube group 33 for superheating refrigerant vapor.

The evaporator 2 includes: a water chamber cover 44 covering the tube sheet 42 of the can 30, a cooled fluid inlet port 45 connected to the water chamber cover 44, and a cooled fluid outlet port 46. A water chamber cover 51 covering the tube plate 50 of the tank 30 is provided on the rotation side of the evaporator 2. Fluid chamber 52 is formed inside water chamber cover 51. The tube sheets 42, 50 constitute the side walls of the tank 30. The temperature sensor S1 as an inlet temperature measuring device is attached to the cooling target fluid inlet port 45, and the temperature sensor S2 as an outlet temperature measuring device is attached to the cooling target fluid outlet of the superheating heat transfer tube group 33.

Fig. 3 is a sectional view taken along line a-a of fig. 2, fig. 4 is a sectional view taken along line B-B of fig. 2, the heat transfer tube group 31-1 of the th flow constitutes a evaporation heat transfer tube group 32A for evaporating a refrigerant liquid to generate a refrigerant vapor, and a superheating heat transfer tube group 33 for superheating the refrigerant vapor, the heat transfer tube group 31-2 of the second flow constitutes a second evaporation heat transfer tube group 32B, and the evaporation heat transfer tube group 32A constituting the portion of the heat transfer tube group 31-1 of the th flow is disposed below the second evaporation heat transfer tube group 32B of the heat transfer tube group 31-2 constituting the second flow.

In the following description, the th evaporation heat transfer tube group 32A and the second evaporation heat transfer tube group 32B are collectively referred to as an evaporation heat transfer tube group 32, the evaporation heat transfer tube group 32 and the superheating heat transfer tube group 33 are disposed in the tank body 30, the refrigerant distribution unit 40 is disposed above the evaporation heat transfer tube group 32, and is disposed so as to supply the refrigerant liquid to the evaporation heat transfer tube group 32 from above the evaporation heat transfer tube group 32, and the refrigerant distribution unit 40 includes a refrigerant liquid inlet 5 and a plurality of nozzle tubes 48 connected to the refrigerant liquid inlet 5, and the refrigerant liquid flows into the refrigerant liquid inlet 5 and is distributed from the nozzle tubes 48 to the evaporation heat transfer tube group 32.

The superheating heat transfer tube group 33 is located away from the evaporating heat transfer tube group 32. More specifically, the superheating heat transfer tube group 33 is located beside the evaporating heat transfer tube group 32. In the present embodiment, two superheating heat transfer tube groups 33 are provided, and the two superheating heat transfer tube groups 33 are disposed on both sides of the evaporation heat transfer tube group 32. The upper end of the superheating heat transfer tube group 33 is located higher than the upper end of the evaporation heat transfer tube group 32, and the lower end of the superheating heat transfer tube group 33 is located lower than the upper end of the evaporation heat transfer tube group 32.

As shown in fig. 4, the evaporator 2 further includes a partition plate 57 that partitions a fluid chamber formed between the tube plate 42 and the water chamber cover 44 (see fig. 2) into a first fluid chamber 53 and a second fluid chamber 54, the partition plate 57 is fixed to the tube plate 42 or the water chamber cover 44, the tube plate 42 forms a side wall of the tank 30, the water chamber cover 44 is connected to the tube plate 42, the cooled fluid inlet port 45 communicates with the first fluid chamber 53, the cooled fluid outlet port 46 communicates with the second fluid chamber 54, the ends of the superheating heat transfer tube group 33 and the first evaporation heat transfer tube group 32A communicate with the -th fluid chamber 53, the other ends of the superheating heat transfer tube group 33 and the first evaporation heat transfer tube group 32A communicate with the fluid chamber 52 (see fig. 2) on the return side, the end of the second evaporation heat transfer tube group 32B communicates with the second fluid chamber 54, and the other end of the second evaporation heat transfer tube group 32B communicates with the fluid chamber 52 (see fig. 2) on the return.

The fluid to be cooled (for example, cold water) flows into the -th fluid chamber 53 through the fluid to be cooled inlet port 45 and fills the -th fluid chamber 53. the fluid to be cooled flows through the -th evaporation heat transfer tube group 32A and the superheating heat transfer tube group 33 that communicate with the -th fluid chamber 53 and flows into the fluid chamber 52 (see fig. 2). the fluid to be cooled that fills the fluid chamber 52 flows through the second evaporation heat transfer tube group 32B and flows into the second fluid chamber 54. the fluid to be cooled flows out from the second fluid chamber 54 through the fluid to be cooled outlet port 46.

The refrigerant liquid is distributed from the refrigerant distribution unit 40 to the evaporation heat transfer tube groups 32 (the th evaporation heat transfer tube group 32A and the second evaporation heat transfer tube group 32B), the refrigerant liquid contacts the surfaces of the evaporation heat transfer tube groups 32, evaporates by heat exchange with the fluid to be cooled flowing in the evaporation heat transfer tube groups 32, and becomes refrigerant vapor, the refrigerant vapor flows out from both sides of the evaporation heat transfer tube groups 32 as indicated by arrows in fig. 3, rises in the tank body 30, and the refrigerant vapor contacts the surfaces of the superheating heat transfer tube groups 33, and is superheated by the fluid to be cooled flowing in the superheating heat transfer tube groups 33, the superheating heat transfer tube groups 33 are constituted by the portions of the heat transfer tube groups 31-1 (see fig. 2) of the th flow, and the fluid to be cooled flowing in the heat transfer tube group 31-1 of the th flow has a relatively high temperature, and therefore, the superheating heat transfer tube groups 33 can superheat the refrigerant vapor efficiently, and can evaporate the mist-like refrigerant contained in the vapor.

The superheated refrigerant vapor flows out through the refrigerant vapor outlet 6 provided at the top of the can 30. The refrigerant vapor outlet 6 is connected to a suction port of the compressor 1 shown in fig. 1 by a refrigerant pipe 4A. Therefore, the refrigerant vapor flows through the refrigerant pipe 4A and is introduced into the compressor 1.

The superheating heat transfer tube group 33 and the evaporation heat transfer tube group 32 are provided separately. With this arrangement, the evaporation heat transfer tube group 32 itself can be reduced in size, and the refrigerant liquid can be distributed not only to the upper portion of the evaporation heat transfer tube group 32 but also to the side portions and the lower portion of the evaporation heat transfer tube group 32. Therefore, the entire evaporation heat transfer tube group 32 can contribute to evaporation of the refrigerant liquid. The heat transfer tubes constituting the evaporation heat transfer tube group 32 are covered with a refrigerant liquid film, thereby avoiding a dry state of the heat transfer tubes. Therefore, it is possible to prevent the lubricant oil contained in the refrigerant liquid (lubricant oil used in the compressor 1) from adhering to the surface of the heat transfer pipe, and as a result, it is possible to improve the heat exchange efficiency between the refrigerant liquid and the fluid to be cooled (for example, cold water) flowing in the heat transfer pipe.

As shown in fig. 3, the evaporator 2 further includes a baffle 60 that prevents upward flow of refrigerant vapor generated by contact between the evaporation heat transfer tube group 32 and the refrigerant liquid. The baffle 60 is disposed above the evaporation heat transfer tube group 32. In the present embodiment, the lower surface of the baffle 60 is located at a position lower than the upper ends of the superheating heat transfer tube groups 33, and the superheating heat transfer tube groups 33 are disposed on both sides of the baffle 60. The baffle 60 has a width greater than the width of the evaporative heat transfer tube array 32.

The baffle 60 can guide the refrigerant vapor generated by flashing the portion of the refrigerant dispersed from the refrigerant dispersion unit 40 and the refrigerant vapor generated by contact between the evaporation heat transfer tube group 32 and the refrigerant liquid to the superheating heat transfer tube group 33 while shifting the flow of the refrigerant vapor in the lateral direction, and the refrigerant vapor is superheated by the superheating heat transfer tube group 33, thereby evaporating the mist-like refrigerant contained in the refrigerant vapor, and therefore, suction of the mist-like refrigerant into the compressor 1 can be prevented.

The evaporator 2 further includes a refrigerant vapor guide plate 63 disposed between the evaporation heat transfer tube group 32 and the superheating heat transfer tube group 33. The refrigerant vapor guide plates 63 are fixed to both side ends of the baffle plate 60. The refrigerant vapor guide plate 63 extends downward from the baffle 60.

The effect of the refrigerant vapor guide plate 63 is as follows, the evaporator 2 is connected to the suction port of the compressor 1, and therefore the pressure inside the tank 30 becomes low, the refrigerant liquid is sent from the condenser 3 to the evaporator 2 and is spread from the refrigerant spreading means 40, at this time, portions of the refrigerant liquid are instantaneously evaporated (flash evaporated) to form a jet of the refrigerant, the refrigerant vapor guide plate 63 can prevent the scattering of the jet of the refrigerant, further, the refrigerant vapor guide plate 63 guides the vapor flow of the refrigerant downward to the evaporation heat transfer tube group 32, portions of the refrigerant liquid are removed from the surface of the heat transfer tubes constituting the upper portion of the evaporation heat transfer tube group 32 toward the vapor flow of the refrigerant downward, and the film thickness of the refrigerant liquid on the heat transfer tubes in the upper portion is reduced, and as a result, the refrigerant liquid is supplied to the entire evaporation heat transfer tube group 32, and.

The refrigerant vapor present in the gaps in the evaporation heat transfer tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then flows laterally from the evaporation heat transfer tube group 32. The refrigerant vapor flows through a space existing between the evaporation heat transfer tube group 32 and the superheating heat transfer tube group 33 before contacting the superheating heat transfer tube group 33. At this time, the flow velocity of the refrigerant vapor decreases, and therefore droplets of the refrigerant contained in the refrigerant vapor fall by their own weight. Therefore, the droplets of the refrigerant present in the refrigerant vapor are greatly reduced, and the refrigerant vapor in a substantially saturated state contacts the superheating heat transfer tube group 33. As a result, the superheating effect in the superheating heat transfer tube group 33 is improved.

The lower end of the refrigerant vapor guide plate 63 is located at a position lower than the entire superheating heat transfer tube group 33. The refrigerant vapor guide plate 63 arranged in this way can guide almost all of the refrigerant vapor that has passed through the evaporation heat transfer tube group 32 to the superheating heat transfer tube group 33.

As shown in fig. 3, the evaporator 2 further includes restricting walls 65 disposed on both sides of the refrigerant distribution unit 40. The restricting walls 65 are disposed above both edges of the evaporation heat transfer tube group 32 and are located inside the refrigerant vapor guide plate 63. Fig. 5 is an enlarged view showing the refrigerant spreading unit 40, the refrigerant vapor guide plate 63, and the restricting wall 65. The restricting wall 65 can prevent scattering of the refrigerant liquid discharged from the refrigerant dispersion unit 40. The refrigerant liquid in contact with the limiting wall 65 drips down from the limiting wall 65 and contacts the heat transfer tubes constituting both edges of the evaporation heat transfer tube group 32. Therefore, the refrigerant liquid is supplied over the entire width of the evaporation heat transfer tube group 32, and the heat exchange efficiency between the fluid to be cooled flowing through the evaporation heat transfer tube group 32 and the refrigerant liquid can be improved.

In the present embodiment, heat transfer tubes having a large outer surface area, such as heat transfer tubes having high fins, are used as the heat transfer tubes constituting the superheating heat transfer tube group 33. That is, the outer surface area per unit length of the heat transfer tubes constituting the superheating heat transfer tube group 33 is larger than the outer surface area per unit length of the heat transfer tubes constituting the evaporation heat transfer tube group 32. The heat transfer tubes constituting the superheating heat transfer tube group 33 can promote heat transfer of the refrigerant vapor outside the tubes and heat exchange between the refrigerant vapor outside the tubes and the fluid to be cooled inside the tubes, and therefore the number of heat transfer tubes constituting the superheating heat transfer tube group 33 can be reduced.

When the liquid refrigerant in the refrigerant vapor evaporates by contact with the superheating heat transfer tube group 33, the difference between the inlet temperature and the outlet temperature of the fluid to be cooled rapidly changes. That is, the change in the difference between the inlet temperature and the outlet temperature of the fluid to be cooled reflects the amount of liquid refrigerant in the refrigerant vapor that contacts the superheating heat transfer tube group 33. Therefore, the valve control unit 10 can precisely control the opening degree of the expansion valve 22 or 25, that is, the degree of superheat, based on the difference between the inlet temperature and the outlet temperature of the fluid to be cooled. In addition, according to the present invention, since it is not necessary to provide a liquid level sensor in the evaporator 2, the expansion valves 22 and 25 can be controlled at a low cost.

Fig. 6 is an enlarged view of embodiments showing the arrangement of the refrigerant distribution unit 40, the baffle 60, and the restricting wall 65, and fig. 7 is a view seen from the direction indicated by the arrow C in fig. 6. the refrigerant distribution unit 40 includes the refrigerant liquid inlet 5, the header 49 connected to the refrigerant liquid inlet 5, and the plurality of nozzle tubes 48 connected to the header 49. the nozzle tubes 48 are fixed to the header 49. a plurality of openings 48a are provided in the lower portion of each nozzle tube 48. the refrigerant liquid flows in the order of the refrigerant liquid inlet 5, the header 49, and the nozzle tube 48, and is distributed from the openings 48 a.

The baffle 60 and the refrigerant distribution unit 40 are -body structures, and according to the present embodiment, the operation of disposing the baffle 60 and the refrigerant distribution unit 40 separately in the tank body 30 is not required, and therefore, the evaporator 2 can be easily assembled.

Fig. 8 is an enlarged view showing another embodiment of the arrangement of the refrigerant distribution unit 40, the baffle 60, and the restricting wall 65, and fig. 9 is a view seen from the direction indicated by the arrow D in fig. 8. In the present embodiment, the refrigerant distribution unit 40 includes a hollow tank 68 connected to the refrigerant liquid inlet 5, and a plurality of openings 68a are formed in a lower surface of the hollow tank 68. The hollow case 68 also functions as the baffle 60. That is, the hollow tank 68 constitutes the refrigerant dispersion unit 40, and constitutes the baffle 60. The refrigerant vapor guide plates 63 are fixed to both side ends of the hollow tank 68 (baffle plate 60), and the restricting walls 65 are fixed to the lower surface of the hollow tank 68 (baffle plate 60). The refrigerant liquid flows in the order of the refrigerant liquid inlet 5, the hollow tank 68, and is dispersed from the opening 68 a. According to the present embodiment, the refrigerant dispersion unit 40 and the baffle 60 having a simpler configuration can be realized.

Fig. 10 is a sectional view of another embodiment of evaporator 2, and fig. 11 is a sectional view of water chamber cover 44 of evaporator 2 of the embodiment shown in fig. 10. The details of the present embodiment not particularly described are the same as those of the embodiment described with reference to fig. 2 to 4, and therefore, redundant description thereof will be omitted. In the present embodiment, the cross-sectional shape of the superheating heat transfer tube group 33 is inclined downward toward the outside. The entirety of the superheating heat transfer tube group 33 is located at a position lower than the upper end of the evaporation heat transfer tube group 32 and at a position higher than the lower end of the evaporation heat transfer tube group 32.

The lower end of the refrigerant vapor guide plate 63 is located at a position lower than the inner lower end of the superheating heat transfer tube group 33. Therefore, as in the embodiment described with reference to fig. 2 to 4, the refrigerant vapor present in the gaps in the evaporation heat transfer tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then flows laterally from the evaporation heat transfer tube group 32. While the refrigerant vapor flows through the space between the evaporation heat transfer tube group 32 and the superheating heat transfer tube group 33, droplets of the refrigerant contained in the refrigerant vapor fall by their own weight. Therefore, the droplets of the refrigerant present in the refrigerant vapor are greatly reduced, and the refrigerant vapor in a substantially saturated state contacts the superheating heat transfer tube group 33. As a result, the superheating effect in the superheating heat transfer tube group 33 is improved.

Fig. 12 is a sectional view of the evaporator 2 according to still another embodiment , and fig. 13 is a sectional view of the header cover 44 of the evaporator 2 according to the embodiment shown in fig. 12, and the details of the present embodiment, which are not described in particular, are the same as those of the embodiment described with reference to fig. 2 to 4, and therefore, redundant description thereof is omitted, and in the present embodiment, the entirety of the superheating heat transfer tube group 33 is located higher than the refrigerant distribution unit 40, the baffle 60, and the evaporation heat transfer tube group 32.

As in the embodiment described with reference to fig. 2 to 4, the refrigerant vapor present in the gaps in the evaporation heat transfer tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then flows sideways from the evaporation heat transfer tube group 32. While the refrigerant vapor flows through the space between the evaporation heat transfer tube group 32 and the superheating heat transfer tube group 33, droplets of the refrigerant contained in the refrigerant vapor fall by their own weight. Therefore, the droplets of the refrigerant present in the refrigerant vapor are greatly reduced, and the refrigerant vapor in a substantially saturated state contacts the superheating heat transfer tube group 33. As a result, the superheating effect in the superheating heat transfer tube group 33 is improved.

In each of the embodiments of the evaporator 2 described above, the heat transfer tube group 31-1 in the th flow path and the heat transfer tube group 31-2 in the second flow path are provided, but the present invention is not limited to the above-described embodiments, and in the embodiments, as shown in fig. 14 and 15, the evaporator 2 may be provided with an evaporation heat transfer tube group 32 and an superheating heat transfer tube group 33 which are constituted only by the heat transfer tube group 31-1 in the th flow path, or the evaporator 2 may be further provided with a heat transfer tube group of a third flow path or more.

The centrifugal refrigerator described above is examples of the compression refrigerator, and the present invention can be applied to a screw refrigerator as another example of the compression refrigerator.

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the art to practice the present invention. It is needless to say that various modifications of the above-described embodiment can be implemented by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention should not be construed as limited to the embodiments described above, but should be construed in the widest scope according to the technical ideas defined by the claims.

Claims (11)

1. The liquid film type evaporator used for a compression refrigerator is characterized by comprising (1) kinds of evaporators;

   a tank body;

   an evaporation heat transfer tube group disposed in the tank body;

   a superheating heat transfer tube group disposed in the tank body at a position apart from the evaporation heat transfer tube group;

   a refrigerant distribution unit disposed above the evaporation heat transfer tube group and configured to supply a refrigerant liquid to the evaporation heat transfer tube group; and

   a baffle plate for preventing upward flow of refrigerant vapor generated by flashing of a portion of the refrigerant liquid and refrigerant vapor generated by contact of the evaporation heat transfer tube group with the refrigerant liquid,

   the baffle is disposed above the evaporation heat transfer tube group.
2. 2. An evaporator according to claim 1,

   the baffle plate and the refrigerant distribution unit are in an -body structure.
3. 3. An evaporator according to claim 1,

   the superheating heat transfer tube bank is part of the heat transfer tube bank of the th flow path for the cooled fluid to flow.
4. 4. An evaporator according to claim 3,

   the evaporator further includes:

   the water chamber cover covers the tube plate of the tank body;

   a cooled fluid inlet port connected to the water chamber cover; and

   a partition plate dividing a fluid chamber formed between the tube plate and the water chamber cover into an th fluid chamber and a second fluid chamber,

   the cooled fluid inlet port and the superheating heat transfer tube group are communicated with the th fluid chamber.
5. 5. An evaporator according to claim 1,

   the outer surface area per unit length of the heat transfer tubes constituting the superheating heat transfer tube group is larger than the outer surface area per unit length of the heat transfer tubes constituting the evaporation heat transfer tube group.
6. 6. An evaporator according to claim 1,

   the superheating heat transfer tube group is disposed beside the evaporation heat transfer tube group.
7. 7. An evaporator according to claim 6,

   the evaporator further includes a refrigerant vapor guide plate disposed between the evaporation heat transfer tube group and the superheating heat transfer tube group,

   the refrigerant vapor guide plate extends downward from the baffle plate.
8. 8. An evaporator according to claim 7,

   the lower end of the refrigerant vapor guide plate is located at a position lower than the inner lower end of the superheating heat transfer tube group.
9. 9. An evaporator according to claim 1,

   the evaporator further includes restricting walls disposed on both sides of the refrigerant distribution unit,

   the limiting wall is arranged above two edges of the evaporation heat transfer tube group.
10. 10, A compression refrigerator, comprising:

    the evaporator according to any of claims 1 to 9, wherein the evaporator evaporates a refrigerant liquid to generate a refrigerant vapor;

    a compressor that compresses the refrigerant vapor;

    a condenser that condenses the compressed refrigerant vapor to generate the refrigerant liquid; and

    and an expansion valve disposed between the condenser and the evaporator.
11. 11. The compression refrigerator according to claim 10, further comprising:

    an inlet temperature measuring device that measures an inlet temperature of the fluid to be cooled flowing into the superheating heat transfer tube group;

    an outlet temperature measuring device that measures an outlet temperature of the fluid to be cooled that flows out from the group of superheating heat transfer tubes; and

    a valve control unit that controls an opening degree of the expansion valve based on a difference between the inlet temperature and the outlet temperature.

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