JP7423357B2 - Evaporator used in compression refrigerator, and compression refrigerator equipped with the evaporator - Google Patents

Description

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

Compression refrigerators used in refrigeration and air conditioning systems are configured as closed systems containing a refrigerant. Compression refrigerators generally include an evaporator that removes heat from the fluid to be cooled and evaporates the refrigerant to produce a refrigeration effect, and a compressor that compresses the refrigerant vapor evaporated in the evaporator to generate high-pressure refrigerant vapor. A condenser that cools and condenses high-pressure refrigerant vapor with a cooling fluid, and an expansion valve that depressurizes and expands the condensed refrigerant are connected by refrigerant piping.

The expansion valve is controlled based on the magnitude of the superheat (refrigerant vapor temperature at the compressor inlet minus the saturation temperature corresponding to the pressure at the compressor inlet). If the amount of refrigerant circulation increases, there is a risk that the refrigerant liquid will be sucked into the compressor and the compressor will be damaged. Therefore, in order to prevent refrigerant liquid from being sucked into the compressor from the evaporator outlet, expansion valve control is required to maintain the degree of superheat at a certain level (eg, 3 to 5° C.).

Japanese Patent Application Publication No. 6-213515

The evaporator has a group of heat transfer tubes through which the fluid to be cooled flows. The refrigerant liquid that has flowed into the evaporator contacts a portion of the heat transfer tube group and evaporates, becoming refrigerant vapor. Furthermore, the refrigerant vapor contacts other parts of the heat transfer tube group and is superheated. In this manner, the evaporator generates refrigerant vapor from the refrigerant liquid and further superheats the refrigerant vapor, thereby preventing liquid refrigerant from being sucked into the compressor.

However, if the amount of refrigerant liquid to be circulated increases as the refrigeration load increases, there is a risk that the refrigerant liquid will scatter and the liquid refrigerant will be sucked into the compressor. In order to avoid this, it is necessary to increase the number of heat transfer tube groups, and the evaporator itself becomes larger. Furthermore, when the circulating amount of the refrigerant liquid decreases, the area of the heat transfer tubes that cannot contribute to evaporation or superheating of the refrigerant increases, and the heat exchange efficiency between the refrigerant and the fluid to be cooled decreases.

Therefore, the present invention provides an evaporator that can effectively use a group of heat transfer tubes for evaporating and superheating a refrigerant. The present invention also provides a compression refrigerator equipped with such an evaporator.

In one aspect, a liquid film type evaporator used in a compression refrigerator includes a can body, a group of evaporation heat transfer tubes arranged in the can body, and a group of evaporation heat transfer tubes arranged in the can body, and a group of superheating heat transfer tubes located at a position apart from the group of heat transfer tubes for evaporation; a refrigerant distribution means disposed above the group of heat transfer tubes for evaporation and supplying a refrigerant liquid to the group of heat transfer tubes for evaporation; and the refrigerant liquid. A baffle plate is provided for blocking upward flow of refrigerant vapor generated by flashing a part of the evaporating heat exchanger tube group and the refrigerant vapor generated by contact between the evaporating heat transfer tube group and the refrigerant liquid, and the baffle plate includes: An evaporator is provided that is disposed above the group of evaporation heat exchanger tubes.

According to the present invention, the superheating heat exchanger tube group is provided separately from the evaporation heat exchanger tube group. With this arrangement, the evaporation heat exchanger tube group itself can be made smaller, and the refrigerant liquid can be spread not only on the upper part of the evaporation heat exchanger tube group but also on the sides and lower part of the evaporation heat exchanger tube group. Therefore, the entire evaporation heat exchanger tube group can contribute to the evaporation of the refrigerant liquid. Moreover, each heat exchanger tube constituting the evaporation heat exchanger tube group is covered with a film of refrigerant liquid, and a dry state of the heat exchanger tubes is avoided. Therefore, the lubricating oil contained in the refrigerant liquid is prevented from adhering to the surface of the heat exchanger tube, and as a result, the heat exchange efficiency between the cooled fluid (for example, cold water) flowing inside the heat exchanger tube and the refrigerant liquid can be improved. can.
The baffle plate diverts the flow of refrigerant vapor generated by flashing of a part of the refrigerant liquid and the flow of refrigerant vapor generated by contact between the evaporation heat transfer tube group and the refrigerant liquid to the side and guides it to the superheating heat transfer tube group. Can be done. The refrigerant vapor is superheated by the superheating heat transfer tube group, and the mist of refrigerant contained in the refrigerant vapor evaporates. Therefore, it is possible to prevent mist-like refrigerant from being sucked into the compressor.

In one aspect, the baffle plate and the refrigerant distribution means are an integral structure.
According to the present invention, it is not necessary to separately arrange the baffle plate and the refrigerant distribution means in the can body, so the evaporator can be easily assembled.

In one aspect, the superheating heat exchanger tube group is part of a first pass heat exchanger tube group through which the fluid to be cooled flows.
The fluid to be cooled flowing through the first pass heat transfer tube group has a relatively high temperature. Therefore, the superheating heat transfer tube group can superheat the refrigerant vapor with high efficiency, and can evaporate the mist-like refrigerant contained in the refrigerant vapor.

In one aspect, the evaporator includes a water chamber cover that covers a tube sheet of the can body, a cooled fluid inlet port connected to the water chamber cover, and a water chamber cover formed between the tube sheet and the water chamber cover. The cooling apparatus further includes a partition plate that partitions the fluid chamber into a first fluid chamber and a second fluid chamber, and the cooled fluid inlet port and the superheating heat transfer tube group communicate with the first fluid chamber.

In one embodiment, the outer surface area per unit length of the heat exchanger tubes constituting the group of heat exchanger tubes for superheating is larger than the outer surface area per unit length of the heat exchanger tubes constituting the group of heat exchanger tubes for evaporation.
According to the present invention, heat exchanger tubes with a large outer surface area, such as heat exchanger tubes with tall fins, are used as the heat exchanger tubes constituting the group of heat exchanger tubes for superheating. Such heat exchanger tubes can promote heat transfer of refrigerant vapor outside the tubes, and can promote heat exchange between refrigerant vapor outside the tubes and the fluid to be cooled inside the tubes, so they constitute a group of heat exchanger tubes for superheating. The number of heat exchanger tubes can be reduced.

In one aspect, the superheating heat exchanger tube group is arranged beside the evaporation heat exchanger tube group.
In one aspect, the evaporator further includes a refrigerant vapor guide plate disposed between the evaporation heat exchanger tube group and the superheating heat exchanger tube group, and the refrigerant vapor guide plate extends from the baffle plate. extends downward.

Since the evaporator is connected to the suction port of the compressor, the pressure inside the can body is low. The refrigerant liquid is sent from the condenser to the evaporator and is distributed from the refrigerant distribution means. At this time, a portion of the refrigerant liquid momentarily evaporates (flashes), forming a jet of refrigerant. The refrigerant vapor guide plate can prevent the refrigerant jet from scattering. Further, the refrigerant vapor guide plate guides the refrigerant vapor flow downward to the evaporation heat exchanger tube group. This downward vapor flow of the refrigerant removes a portion of the refrigerant liquid from the surfaces of the heat exchanger tubes forming the upper part of the evaporation heat exchanger tube group, thereby reducing the film thickness of the refrigerant liquid on the upper heat exchanger tubes. As a result, the refrigerant liquid is supplied to the entire group of heat exchanger tubes for evaporation, and evaporation of the refrigerant liquid is promoted.
Moreover, the refrigerant vapor existing in the gap within the evaporation heat exchanger tube group is guided downward by the refrigerant vapor guide plate, and then flows laterally from the evaporation heat exchanger tube group. The refrigerant vapor flows through a space existing between the evaporation heat exchanger tube group and the superheating heat exchanger tube group before coming into contact with the superheating heat exchanger tube group. At this time, since the flow rate of the refrigerant vapor decreases, the refrigerant droplets contained in the refrigerant vapor fall due to their own weight. Therefore, the number of refrigerant droplets present in the refrigerant vapor is significantly reduced, and the almost saturated refrigerant vapor contacts the superheating heat exchanger tube group. As a result, the superheating effect in the superheating heat exchanger tube group is improved.

In one aspect, the lower end of the refrigerant vapor guide plate is located at a lower position than the inner lower end of the superheating heat exchanger tube group.
According to the present invention, almost all of the refrigerant vapor that has passed through the evaporation heat exchanger tube group can be guided to the superheating heat exchanger tube group.

In one aspect, the evaporator further includes block walls arranged on both sides of the refrigerant distribution means, and the block walls are arranged above both edges of the evaporation heat exchanger tube group.
The block wall can prevent the refrigerant liquid discharged from the refrigerant distribution means from scattering. The refrigerant liquid that has come into contact with the block wall drips from the block wall and comes into contact with the heat exchanger tubes forming both edges of the evaporation heat exchanger tube group. Therefore, the refrigerant liquid is supplied over the entire width of the evaporation heat exchanger tube group, and the heat exchange efficiency between the cooled fluid and the refrigerant liquid flowing through the evaporation heat exchanger tube group can be improved.

In one embodiment, the evaporator evaporates refrigerant liquid to generate refrigerant vapor, the compressor compresses the refrigerant vapor, and the condenser condenses the compressed refrigerant vapor to generate the refrigerant liquid; A compression refrigerator is provided, comprising an expansion valve disposed between the condenser and the evaporator.

In one aspect, the compression refrigerator includes an inlet temperature measuring device that measures the inlet temperature of the fluid to be cooled that flows into the group of heat transfer tubes for superheating, and an outlet of the fluid to be cooled that flows out of the group of heat transfer tubes for superheating. The apparatus further includes an outlet temperature measuring device that measures temperature, and a valve control section that controls the opening degree of the expansion valve based on the difference between the inlet temperature and the outlet temperature.

When the liquid refrigerant in the refrigerant vapor evaporates due to contact with the superheating heat transfer tube group, the difference between the inlet temperature and the outlet temperature of the fluid to be cooled changes rapidly. 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 is in contact with the superheating heat exchanger tube group. Therefore, the valve control section can precisely control the degree of opening of the expansion valve, that is, the degree of superheating, based on the difference between the inlet temperature and the outlet temperature of the fluid to be cooled. Further, according to the present invention, since there is no need to provide a liquid level sensor in the evaporator, the expansion valve can be controlled at low cost.

According to the present invention, the evaporation heat exchanger tube group itself can be made smaller, and the refrigerant liquid can be sprayed not only on the upper part of the evaporation heat exchanger tube group but also on the sides and lower part of the evaporation heat exchanger tube group. Therefore, the entire evaporation heat exchanger tube group can contribute to the evaporation of the refrigerant liquid. Moreover, each heat exchanger tube constituting the evaporation heat exchanger tube group is covered with a film of refrigerant liquid, and a dry state of the heat exchanger tubes is avoided. Therefore, the lubricating oil contained in the refrigerant liquid (lubricating oil used in the compressor) is prevented from adhering to the surface of the heat transfer tube, and as a result, the fluid to be cooled (e.g. cold water) and the refrigerant liquid flowing inside the heat transfer tube are prevented from adhering to the surface of the heat transfer tube. It is possible to improve the heat exchange efficiency with The baffle plate can divert laterally the flow of refrigerant vapor generated by contact between the evaporation heat exchanger tube group and the refrigerant liquid and guide it to the superheating heat exchanger tube group. The refrigerant vapor is superheated by the superheating heat transfer tube group, and the mist of refrigerant contained in the refrigerant vapor evaporates. Therefore, it is possible to prevent mist-like refrigerant from being sucked into the compressor.

FIG. 1 is a schematic diagram showing an embodiment of a centrifugal refrigerator. FIG. 2 is a side view of one embodiment of an evaporator. 3 is a sectional view taken along line AA in FIG. 2. FIG. 3 is a sectional view taken along line BB in FIG. 2. FIG. It is an enlarged view showing a refrigerant distribution means, a refrigerant vapor guide plate, and a block wall. FIG. 3 is an enlarged view showing one embodiment of the arrangement of a refrigerant distribution means, a baffle plate, and a block wall. 7 is a view seen from the direction indicated by arrow C in FIG. 6. FIG. FIG. 7 is an enlarged view showing another embodiment of the arrangement of a refrigerant distribution means, a baffle plate, and a block wall. 9 is a view seen from the direction indicated by arrow D in FIG. 8. FIG. FIG. 3 is a cross-sectional view of another embodiment of an evaporator. 11 is a sectional view of the water chamber cover of the evaporator according to the embodiment shown in FIG. 10. FIG. FIG. 7 is a cross-sectional view of yet another embodiment of an evaporator. 13 is a sectional view of the water chamber cover of the evaporator according to the embodiment shown in FIG. 12. FIG. FIG. 7 is a cross-sectional view of yet another embodiment of an evaporator. 15 is a sectional view of the water chamber cover of the evaporator according to the embodiment shown in FIG. 14. FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing one embodiment of a centrifugal refrigerator. A centrifugal refrigerator is an example of a compression refrigerator. As shown in Figure 1, a centrifugal refrigerator consists of an evaporator 2 that evaporates refrigerant liquid to generate refrigerant vapor, a compressor 1 that compresses the refrigerant vapor, and a refrigerant liquid that condenses the compressed refrigerant vapor. It is equipped with a condenser 3 that generates . 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 a refrigerant vapor outlet 6 of the evaporator 2 by a refrigerant pipe 4A. The discharge port of the compressor 1 is connected to the condenser 3 by a refrigerant pipe 4B.

The centrifugal refrigerator further includes an economizer 9 disposed between the condenser 3 and the evaporator 2. The condenser 3 is connected to the economizer 9 by a refrigerant pipe 4C, and the economizer 9 is connected to the evaporator 2 by a refrigerant pipe 4D. Furthermore, the economizer 9 is connected to the compressor 1 by a refrigerant pipe 4E. Economizer 9 is an intercooler placed between condenser 3 and evaporator 2. An expansion valve 21 is attached to the refrigerant pipe 4C extending from the condenser 3 to the economizer 9, and an expansion valve 22 is attached to the refrigerant pipe 4D extending from the economizer 9 to the evaporator 2. The expansion valves 21 and 22 are configured so that their opening degrees can be adjusted, and are configured, for example, from electrically operated valves whose opening degrees are variable. Each of the expansion valves 21 and 22 may include an expansion valve and an orifice arranged in parallel. Furthermore, one of the expansion valves 21 and 22 may be adjustable in flow rate, and one may be a fixed orifice.

In this embodiment, the compressor 1 is comprised of a multi-stage centrifugal compressor. More specifically, the compressor 1 is a two-stage centrifugal compressor, and includes a first-stage impeller 11, a second-stage impeller 12, and an electric motor 13 that rotates these impellers 11 and 12. There is.

A guide vane 16 is arranged at the suction port of the compressor 1 to adjust the flow rate of refrigerant vapor sucked into the impellers 11 and 12. The guide vane 16 is located on the suction side of the first stage impeller 11. The guide vanes 16 are arranged radially, 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 its own axis. Refrigerant vapor sent from the evaporator 2 passes through a guide vane 16 and is then sequentially pressurized by rotating impellers 11 and 12. The pressurized refrigerant vapor is sent to the condenser 3 through the refrigerant pipe 4B.

The centrifugal refrigerator includes a bypass line 20 that guides refrigerant vapor from the condenser 3 to the evaporator 2, and an expansion valve (hot gas bypass valve) 25 that opens and closes the bypass line 20. Bypass line 20 extends by bypassing economizer 9. One end of the bypass line 20 is connected to the refrigerant pipe 4C, and the other end of the bypass line 20 is connected to the refrigerant pipe 4D. The expansion valve 25 is configured such that its opening degree can be adjusted, and is composed of, for example, an electric valve whose opening degree is variable.

The expansion valves 21 , 22 , 25 are electrically connected to the valve control section 10 , and the operations of the expansion valves 21 , 22 , 25 are controlled by the valve control section 10 . In steady 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 passes through the bypass line 20 from the condenser 3 to the evaporator 2. Sent.

The evaporator 2 removes heat from the fluid to be cooled (for example, cold water), evaporates the refrigerant liquid, and exhibits a refrigeration effect. 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 a cooling fluid (for example, cooling water). , producing a refrigerant liquid. The refrigerant liquid is depressurized by passing through the expansion valve 21 . Refrigerant vapor present in the depressurized refrigerant liquid is separated by an economizer 9 and sent to an intermediate suction port 17 provided between a first-stage impeller 11 and a second-stage impeller 12 of the compressor 1 . The refrigerant liquid that has passed through the economizer 9 is depressurized by passing through the expansion valve 22, and is further sent to the evaporator 2 through the refrigerant pipe 4D. In this way, the centrifugal refrigerator is configured as a closed system containing a refrigerant. The economizer 9 may be omitted in some cases.

The centrifugal refrigerator includes a temperature sensor S1 as an inlet temperature measuring device that measures the inlet temperature of the fluid to be cooled flowing into the superheating heat transfer tube group (described later) of the evaporator 2, and a temperature sensor S1 as an inlet temperature measuring device for measuring the inlet temperature of the fluid to be cooled flowing into the superheating heat transfer tube group (described later) of the evaporator 2, and It further includes a temperature sensor S2 as an outlet temperature measuring device for measuring the outlet temperature of the fluid to be cooled. The temperature sensors S1 and S2 are electrically connected to the valve control unit 10, and the output values of the temperature sensors S1 and S2 (i.e., the measured values of the inlet temperature and outlet temperature of the fluid to be cooled) are sent to the valve control unit 10. It is now possible to

FIG. 2 is a side view of one embodiment of the evaporator 2. As shown in FIG. 2, the evaporator 2 includes a can body 30, a group of heat transfer tubes 31 disposed within the can body 30, and a refrigerant distribution means 40. The refrigerant distribution means 40 includes a refrigerant liquid inlet 5, and the refrigerant liquid inlet 5 is connected to the condenser 3 and the economizer 9 via refrigerant pipes 4C and 4D. A refrigerant vapor outlet 6 is provided at the top of the can body 30. In this embodiment, the heat exchanger tube group 31 arranged in the can body 30 includes a first pass heat exchanger tube group 31-1 and a second pass heat exchanger tube group 31-2. In FIG. 2, these heat exchanger tube groups 31-1 and 31-2 are schematically depicted. The first pass heat transfer tube group 31-1 includes a first evaporation heat transfer tube group 32A for evaporating refrigerant liquid to generate refrigerant vapor, and a superheating heat transfer tube group 33 for superheating the refrigerant vapor. .

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

3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a sectional view taken along line BB in FIG. The first pass heat transfer tube group 31-1 includes a first evaporation heat transfer tube group 32A for evaporating refrigerant liquid to generate refrigerant vapor, and a superheating heat transfer tube group 33 for superheating the refrigerant vapor. do. The second pass heat exchanger tube group 31-2 constitutes a second evaporation heat exchanger tube group 32B. The first evaporation heat exchanger tube group 32A, which constitutes a part of the first pass heat exchanger tube group 31-1, is located below the second evaporation heat exchanger tube group 32B, which constitutes the second pass heat exchanger tube group 31-2. It is located.

In the following description, the first evaporation heat exchanger tube group 32A and the second evaporation heat exchanger tube group 32B are collectively referred to as the evaporation heat exchanger tube group 32. The evaporation heat exchanger tube group 32 and the superheating heat exchanger tube group 33 are arranged within the can body 30. The refrigerant distribution means 40 is arranged above the evaporation heat exchanger tube group 32 and is arranged to supply refrigerant liquid to the evaporation heat exchanger tube group 32 from above. The refrigerant distribution means 40 includes a refrigerant liquid inlet 5 and a plurality of nozzle pipes 48 connected to the refrigerant liquid inlet 5. The refrigerant liquid flows into the refrigerant liquid inlet 5 and is sprayed from the nozzle pipe 48 to the evaporation heat exchanger tube group 32.

The superheating heat exchanger tube group 33 is located away from the evaporation heat exchanger tube group 32. More specifically, the superheating heat exchanger tube group 33 is located next to the evaporation heat exchanger tube group 32. In this embodiment, two overheating heat exchanger tube groups 33 are provided, and these two overheating heat exchanger tube groups 33 are arranged on both sides of the evaporation heat exchanger 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 includes a partition plate that partitions a fluid chamber formed between a tube plate 42 and a water chamber cover 44 (see FIG. 2) into a first fluid chamber 53 and a second fluid chamber 54. 57. The partition plate 57 is fixed to the tube plate 42 or the water chamber cover 44. The tube sheet 42 constitutes a side wall of the can body 30, and the water chamber cover 44 is connected to the tube sheet 42. The cooled fluid inlet port 45 communicates with the first fluid chamber 53 , and the cooled fluid outlet port 46 communicates with the second fluid chamber 54 . One end of the superheating heat transfer tube group 33 and the first evaporation heat transfer tube group 32A is connected to the first fluid chamber 53, and the other end of the superheating heat transfer tube group 33 and the first evaporation heat transfer tube group 32A is connected to the turn side. It communicates with the fluid chamber 52 (see FIG. 2). One end of the second evaporative heat transfer tube group 32B communicates with the second fluid chamber 54, and the other end of the second evaporative heat transfer tube group 32B communicates with the fluid chamber 52 on the turn side (see FIG. 2).

Cooled fluid (eg, cold water) enters and fills the first fluid chamber 53 through the cooled fluid inlet port 45 . The fluid to be cooled flows through the first evaporation heat transfer tube group 32A and the superheating heat transfer tube group 33 that communicate with the first fluid chamber 53, and flows into the fluid chamber 52 (see FIG. 2). The fluid to be cooled that has filled the fluid chamber 52 flows through the second evaporation heat transfer tube group 32B and flows into the second fluid chamber 54. Cooled fluid exits second fluid chamber 54 through cooled fluid outlet port 46 .

The refrigerant liquid is distributed from the refrigerant distribution means 40 to the evaporation heat exchanger tube group 32 (first evaporation heat exchanger tube group 32A and second evaporation heat exchanger tube group 32B). The refrigerant liquid contacts the surface of the evaporation heat exchanger tube group 32, evaporates through heat exchange with the fluid to be cooled flowing within the evaporation heat exchanger tube group 32, and becomes refrigerant vapor. The refrigerant vapor flows out from both sides of the evaporation heat transfer tube group 32 and rises inside the can body 30, as shown by the arrows in FIG. Further, the refrigerant vapor comes into contact with the surface of the superheating heat exchanger tube group 33 and is superheated by the fluid to be cooled flowing within the superheating heat exchanger tube group 33. As described above, the superheating heat exchanger tube group 33 is composed of a part of the first pass heat exchanger tube group 31-1 (see FIG. 2). The fluid to be cooled flowing through the first pass heat transfer tube group 31-1 has a relatively high temperature. Therefore, the superheating heat transfer tube group 33 can superheat the refrigerant vapor with high efficiency, and can evaporate the mist-like refrigerant contained in the refrigerant vapor.

The superheated refrigerant vapor flows out through the refrigerant vapor outlet 6 provided at the top of the can body 30. The refrigerant vapor outlet 6 is connected to the 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 exchanger tube group 33 is provided separately from the evaporation heat exchanger tube group 32. With this arrangement, the evaporation heat exchanger tube group 32 itself can be made smaller, and the refrigerant liquid can be spread not only at the top of the evaporation heat exchanger tube group 32 but also at the sides and bottom of the evaporation heat exchanger tube group 32. . Therefore, the entire evaporation heat exchanger tube group 32 can contribute to the evaporation of the refrigerant liquid. Moreover, each heat exchanger tube constituting the evaporation heat exchanger tube group 32 is covered with a film of refrigerant liquid, and a dry state of the heat exchanger tubes is avoided. Therefore, the lubricating oil contained in the refrigerant liquid (the lubricating oil used in the compressor 1) is prevented from adhering to the surface of the heat exchanger tube, and as a result, the fluid to be cooled (for example, cold water) flowing inside the heat exchanger tube and the refrigerant are prevented from adhering to the surface of the heat exchanger tube. The heat exchange efficiency with the liquid can be improved.

As shown in FIG. 3, the evaporator 2 further includes a baffle plate 60 that prevents the refrigerant vapor generated by the contact between the evaporating heat exchanger tube group 32 and the refrigerant liquid from flowing upward. The baffle plate 60 is arranged above the evaporation heat exchanger tube group 32. In this embodiment, the lower surface of the baffle plate 60 is located at a lower position than the upper end of the overheating heat exchanger tube group 33, and the overheating heat exchanger tube group 33 is arranged on both sides of the baffle plate 60. The baffle plate 60 has a width larger than the width of the evaporation heat exchanger tube group 32.

The baffle plate 60 horizontally channels the flow of refrigerant vapor generated by flashing a part of the refrigerant sprayed from the refrigerant distribution means 40 and the flow of refrigerant vapor generated by contact between the evaporation heat transfer tube group 32 and the refrigerant liquid. It can be diverted and guided to the heat exchanger tube group 33 for superheating. The refrigerant vapor is superheated by the superheating heat transfer tube group 33, and the mist-like refrigerant contained in the refrigerant vapor evaporates. Therefore, it is possible to prevent mist-like refrigerant from being sucked into the compressor 1.

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

The effects of the refrigerant vapor guide plate 63 are as follows. Since the evaporator 2 is connected to the suction port of the compressor 1, the pressure inside the can body 30 is low. The refrigerant liquid is sent from the condenser 3 to the evaporator 2 and is distributed from the refrigerant distribution means 40. At this time, a portion of the refrigerant liquid momentarily evaporates (flashes), forming a jet of refrigerant. The refrigerant vapor guide plate 63 can prevent the refrigerant jet from scattering. Further, the refrigerant vapor guide plate 63 guides the refrigerant vapor flow downward to the evaporation heat exchanger tube group 32 . This downward vapor flow of the refrigerant removes a portion of the refrigerant liquid from the surfaces of the heat exchanger tubes forming the upper part of the evaporative heat exchanger tube group 32, thereby reducing the film thickness of the refrigerant liquid on the upper heat exchanger tubes. As a result, the refrigerant liquid is supplied to the entire evaporation heat exchanger tube group 32, and evaporation of the refrigerant liquid is promoted.

Moreover, the refrigerant vapor existing in the gap within the evaporative heat exchanger tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then flows laterally from the evaporative heat exchanger tube group 32. The refrigerant vapor flows through a space existing between the evaporation heat exchanger tube group 32 and the superheating heat exchanger tube group 33 before coming into contact with the superheating heat exchanger tube group 33 . At this time, since the flow rate of the refrigerant vapor decreases, the refrigerant droplets contained in the refrigerant vapor fall due to their own weight. Therefore, the number of refrigerant droplets present in the refrigerant vapor is significantly reduced, and the almost saturated refrigerant vapor contacts the superheating heat exchanger tube group 33. As a result, the superheating effect in the superheating heat exchanger tube group 33 is improved.

The lower end of the refrigerant vapor guide plate 63 is located at a lower position than the entire superheating heat exchanger tube group 33. The refrigerant vapor guide plate 63 arranged in this manner 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 block walls 65 disposed on both sides of the refrigerant distribution means 40. As shown in FIG. The block wall 65 is arranged above both edges of the evaporation heat exchanger tube group 32 and is located inside the refrigerant vapor guide plate 63. FIG. 5 is an enlarged view showing the refrigerant distribution means 40, the refrigerant vapor guide plate 63, and the block wall 65. The block wall 65 can prevent the refrigerant liquid discharged from the refrigerant distribution means 40 from scattering. The refrigerant liquid that has come into contact with the block wall 65 drips from the block wall 65 and comes into contact with the heat exchanger tubes forming both edges of the evaporation heat exchanger tube group 32 . Therefore, the refrigerant liquid is supplied over the entire width of the evaporation heat exchanger tube group 32, and the heat exchange efficiency between the cooled fluid flowing through the evaporation heat exchanger tube group 32 and the refrigerant liquid can be improved.

In this embodiment, the heat exchanger tubes constituting the superheating heat exchanger tube group 33 are heat exchanger tubes with a large outer surface area, such as heat exchanger tubes with tall fins. That is, the outer surface area per unit length of the heat exchanger tubes constituting the group 33 of heat exchanger tubes for superheating is larger than the outer surface area per unit length of the heat exchanger tubes constituting the group 32 of heat exchanger tubes for evaporation. The heat transfer tubes constituting the superheating heat transfer tube group 33 can promote heat transfer of the refrigerant vapor outside the tubes, and can promote heat exchange between the refrigerant vapor outside the tubes and the fluid to be cooled inside the tubes. , the number of heat exchanger tubes that constitute the overheating heat exchanger tube group 33 can be reduced.

When the liquid refrigerant in the refrigerant vapor evaporates due to 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 changes rapidly. 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 is in contact with the superheating heat transfer tube group 33. Therefore, the valve control unit 10 can precisely control the degree of opening of the expansion valve 22 or the expansion valve 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. Further, according to the present invention, since there is no need to provide a liquid level sensor in the evaporator 2, the expansion valves 22 and 25 can be controlled at low cost.

FIG. 6 is an enlarged view showing one embodiment of the arrangement of the refrigerant distribution means 40, the baffle plate 60, and the block wall 65, and FIG. 7 is a view seen from the direction indicated by arrow C in FIG. The refrigerant distribution means 40 includes a refrigerant liquid inlet 5, a header pipe 49 connected to the refrigerant liquid inlet 5, and a plurality of nozzle pipes 48 connected to the header pipe 49. The nozzle pipe 48 is fixed to a header pipe 49. A plurality of openings 48a are provided at the bottom of each nozzle pipe 48. The refrigerant liquid flows through the refrigerant liquid inlet 5, the header pipe 49, and the nozzle pipe 48 in this order, and is sprayed from the opening 48a.

Refrigerant liquid inlet 5 extends through baffle plate 60 . The baffle plate 60 is fixed to the refrigerant liquid inlet 5 and the header pipe 49. Therefore, the baffle plate 60 and the refrigerant distribution means 40 are an integral structure. According to this embodiment, it is not necessary to separately arrange the baffle plate 60 and the refrigerant distribution means 40 inside the can body 30, so the evaporator 2 can be assembled easily.

FIG. 8 is an enlarged view showing another embodiment of the arrangement of the refrigerant distribution means 40, the baffle plate 60, and the block wall 65, and FIG. 9 is a view seen from the direction indicated by arrow D in FIG. In this embodiment, the refrigerant distribution means 40 includes a hollow box 68 connected to the refrigerant liquid inlet 5, and a plurality of openings 68a are formed in the lower surface of the hollow box 68. The hollow box 68 also functions as a baffle plate 60. That is, the hollow box 68 constitutes the baffle plate 60 while constituting the refrigerant dispersing means 40 . The refrigerant vapor guide plate 63 is fixed to both ends of the hollow box 68 (baffle plate 60), and the block wall 65 is fixed to the lower surface of the hollow box 68 (baffle plate 60). The refrigerant liquid flows through the refrigerant liquid inlet 5 and the hollow box 68 in this order, and is dispersed from the opening 68a. According to this embodiment, the refrigerant distribution means 40 and the baffle plate 60 having a simpler structure can be achieved.

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

The lower end of the refrigerant vapor guide plate 63 is located at a lower position than the inner lower end of the superheating heat exchanger tube group 33. Therefore, similar to the embodiment described with reference to FIGS. 2 to 4, the refrigerant vapor existing in the gap in the evaporative heat transfer tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then It flows laterally from the heat exchanger tube group 32. While the refrigerant vapor flows through the space existing 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 due to their own weight. Therefore, the number of refrigerant droplets present in the refrigerant vapor is significantly reduced, and the almost saturated refrigerant vapor contacts the superheating heat exchanger tube group 33. As a result, the superheating effect in the superheating heat exchanger tube group 33 is improved.

FIG. 12 is a sectional view of still another embodiment of the evaporator 2, and FIG. 13 is a sectional view of the water chamber cover 44 of the evaporator 2 according to the embodiment shown in FIG. Details of this embodiment that are not particularly described are the same as those of the embodiment described with reference to FIGS. 2 to 4, and therefore, redundant description thereof will be omitted. In this embodiment, the entire superheating heat exchanger tube group 33 is located at a higher position than the refrigerant distribution means 40, the baffle plate 60, and the evaporation heat exchanger tube group 32.

Similar to the embodiment described with reference to FIGS. 2 to 4, the refrigerant vapor present in the gap in the evaporation heat exchanger tube group 32 is guided downward by the refrigerant vapor guide plate 63, and then the evaporation heat exchanger tube Flows laterally from group 32. While the refrigerant vapor flows through the space existing 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 due to their own weight. Therefore, the number of refrigerant droplets present in the refrigerant vapor is significantly reduced, and the almost saturated refrigerant vapor contacts the superheating heat exchanger tube group 33. As a result, the superheating effect in the superheating heat exchanger tube group 33 is improved.

Although each of the embodiments of the evaporator 2 described above includes a first-pass heat exchanger tube group 31-1 and a second-pass heat exchanger tube group 31-2, the present invention is not limited to these embodiments. In one embodiment, as shown in FIGS. 14 and 15, the evaporator 2 may include an evaporation heat exchanger tube group 32 and a superheating heat exchanger tube group 33, which are comprised only of the first pass heat exchanger tube group 31-1. . Alternatively, the evaporator 2 may further include a third or more pass heat exchanger tube group.

The centrifugal refrigerator mentioned above is an example of a compression refrigerator. The present invention can be similarly applied to a screw refrigerator, which is another example of a compression refrigerator.

The embodiments described above have been described to enable those skilled in the art to carry out the invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the invention is not limited to the described embodiments, but is to be construed in the broadest scope according to the spirit defined by the claims.

1 Compressor 2 Evaporator 3 Condenser 4A, 4B, 4C, 4D, 4E Refrigerant piping 5 Refrigerant liquid inlet 6 Refrigerant vapor outlet 9 Economizer 10 Valve control unit 11 First stage impeller 12 Second stage impeller 13 Electric motor 16 Guide vane 17 Intermediate suction port 20 Bypass lines 21, 22, 25 Expansion valve 30 Can body 31 Heat exchanger tube group 31-1 1st pass heat exchanger tube group 31-2 2nd pass heat exchanger tube group 32 Evaporation heat exchanger tube group 32A 1st Evaporation heat transfer tube group 32B Second evaporation heat transfer tube group 33 Superheating heat transfer tube group 40 Refrigerant distribution means 42 Tube plate 44 Water chamber cover 45 Cooled fluid inlet port 46 Cooled fluid outlet port 48 Nozzle pipe 49 Header pipe 53 No. 1 fluid chamber 54 2nd fluid chamber 57 Partition plate 60 Baffle plate 63 Refrigerant vapor guide plate 65 Block wall 68 Hollow box S1 Temperature sensor S2 Temperature sensor

Claims (8)

A liquid film type evaporator used in a compression refrigerator,
Can body and
a group of evaporation heat exchanger tubes arranged in the can body;
a superheating heat transfer tube group disposed within the can body and located away from the evaporation heat transfer tube group;
a refrigerant dispersing means disposed above the evaporation heat exchanger tube group and supplying refrigerant liquid to the evaporation heat exchanger tube group;
a baffle plate that prevents upward flow of refrigerant vapor generated by flashing a portion of the refrigerant liquid and refrigerant vapor generated by contact between the evaporation heat transfer tube group and the refrigerant liquid;
comprising a refrigerant vapor guide plate disposed between the evaporation heat exchanger tube group and the superheating heat exchanger tube group ,
The baffle plate is arranged above the evaporation heat exchanger tube group ,
The superheating heat exchanger tube group is arranged next to the evaporation heat exchanger tube group,
The refrigerant vapor guide plate extends downward from the baffle plate,
The lower end of the refrigerant vapor guide plate is located at a lower position than the inner lower end of the superheating heat exchanger tube group . The evaporator according to claim 1, wherein the baffle plate and the refrigerant distribution means are an integral structure. The evaporator according to claim 1 or 2, wherein the superheating heat transfer tube group is a part of a first pass heat transfer tube group through which the fluid to be cooled flows. The evaporator is
a water chamber cover that covers the tube plate of the can body;
a cooled fluid inlet port connected to the water chamber cover;
further comprising a partition plate that partitions the fluid chamber formed between the tube plate and the water chamber cover into a first fluid chamber and a second fluid chamber,
The evaporator according to claim 3, wherein the cooled fluid inlet port and the superheating heat exchanger tube group communicate with the first fluid chamber. The outer surface area per unit length of the heat exchanger tubes constituting the superheating heat exchanger tube group is larger than the outer surface area per unit length of the heat exchanger tubes constituting the evaporation heat exchanger tube group. The evaporator according to any one of the items. The evaporator further includes block walls disposed on both sides of the refrigerant distribution means,
The evaporator according to any one of claims 1 to 5 , wherein the block wall is arranged above both edges of the evaporation heat exchanger tube group. The evaporator according to any one of claims 1 to 6 , which evaporates refrigerant liquid to generate refrigerant vapor;
a compressor that compresses the refrigerant vapor;
a condenser that condenses the compressed refrigerant vapor to produce the refrigerant liquid;
A compression refrigerator comprising an expansion valve disposed between the condenser and the evaporator. an inlet temperature measuring device that measures the inlet temperature of the fluid to be cooled flowing into the superheating heat transfer tube group;
an outlet temperature measuring device that measures the outlet temperature of the fluid to be cooled that has flowed out from the group of superheating heat transfer tubes;
The compression refrigerator according to claim 7 , further comprising a valve control section that controls the opening degree of the expansion valve based on the difference between the inlet temperature and the outlet temperature.

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