WO1999015847A1

WO1999015847A1 - Heat exchanger and absorption water cooler/heater using the heat exchanger

Info

Publication number: WO1999015847A1
Application number: PCT/JP1997/003331
Authority: WO
Inventors: Masayuki Shimamura; Michihiko Aizawa; Tomihisa Oouchi
Original assignee: Hitachi, Ltd.
Priority date: 1997-09-19
Filing date: 1997-09-19
Publication date: 1999-04-01

Abstract

A heat transmission pipe (1) is bent at a plurality of positions into a zig-zag form. A plurality of such zig-zag heat transmission pipes (1) are horizontally arranged side by side. A stack of horizontally arranged heat transmission pipes (1) is so formed that the spacings between the heat transmission pipes (1) are as small as possible. The end parts of the heat transmission pipes (1) are bent at different positions near a pipe plate (2) and inserted into the pipe plate (2). Since the heat transmission pipes (1) are stacked with very small spacings, when liquid which is sprayed onto the horizontal heat transmission pipes flows down from pipe to pipe, the liquid is spread in the direction of the heat transmission pipe by capillarity and the whole surfaces of the heat transmission pipes are well wetted. Consequently, the heat transmissivity can be improved and the size of an absorption water cooler/heater can be reduced.

Description

1 Description

Heat exchanger and absorption chiller / heater using this heat exchanger

The present invention relates to an absorption chiller / heater used for a heat exchanger, an air conditioner, and the like, and more particularly to an absorption chiller / heater that can be downsized by improving the efficiency of a heat exchanger of an evaporator and an absorber.

Background art

Conventionally, heat exchangers used for evaporators, absorbers, low-temperature regenerators, etc. for absorption chillers / heaters have been used in combination with shells and coils, or in combination with general shells and tubes. ing. In particular, in the case of a combination of shell and tube, multiple heat transfer tubes are passed through a high vacuum box-shaped shell, and water is passed through the heat transfer tubes to exchange heat. A box with a partition plate is installed so that the water that passes through the heat transfer tube can be turned multiple times outside the shell. In addition, the inside of the heat transfer tube penetrated through the high vacuum shell must be expanded from the inside of the heat transfer tube penetrated into the hole of the tube sheet and sealed so as to seal the pressure obtained by adding water pressure to atmospheric pressure.

In the Japanese Patent Publication No. 59-2767659, the heat transfer tube penetrating the shell is bent several times into a hairpin shape inside the shell, and the box for turning outside the shell can be omitted. I have. The company says that it can drastically reduce the number of places that need to be expanded in the holes in the tube sheet, thereby significantly reducing processing costs. In the case of the combination of shell and coil, an assembled heat transfer tube is installed inside the high-vacuum shell, which bundles multiple ends of the coiled heat transfer tube. It is sealed by welding or brazing. The seal between the vacuum section and the heat transfer tube is not only expanded, welded, and gusseted, but also the seal is improved by using an adhesive in the hole of the tube sheet and using it together with the expanded tube.

In the heat exchanger of the combination of shell and tube with the above structure, heat transfer tube and heat transfer tube If there is no interval, or the interval is 1 mn! If it is as narrow as ~ 3 mm, the heat transfer tube cannot be brought into close contact with the hole in the tube sheet by expansion. The reason for this is that, because the expansion of the heat transfer tube and the hole formed in the tube sheet are closely adhered to each other by plastic working, if the space between the heat transfer tube and the heat transfer tube is small, the adjacent heat transfer tube will be distorted during the expansion. For this reason, even if the tube is bent and the heat transfer tube adheres tightly, the seal loosens. Therefore, in order to expand the tubes, it is necessary to form a group of heat transfer tubes with a gap of at least 3 mm between the heat transfer tubes, which makes it impossible to reduce the size of the heat exchanger.

In addition, in the evaporator, absorber, and low-temperature regenerator of the absorption type water heater, a refrigerant (generally water) or a solution (generally lithium bromide aqueous solution) is sprayed from above the horizontal heat transfer tube group to evaporate and absorb the liquid. In order to promote the heat transfer, it is important to spray the liquid as evenly as possible and to wet the surface of the heat transfer tube well to contribute to the improvement of the heat exchange rate.

An object of the present invention is to reduce the vertical interval between heat transfer tube groups in a shell and to promote the spread of liquid in the axial direction of the heat transfer tube by capillary action when the liquid flows down from the heat transfer tube to the heat transfer tube. An object of the present invention is to provide a heat exchanger that can be downsized by improving the exchange rate and reducing the vertical spacing of the heat transfer tubes, and a compact absorption chiller / heater using the heat exchanger.

Disclosure of the invention

The above object is achieved by inserting the end of the heat transfer tube into a tube sheet, bringing the heat transfer tube into close contact with the tube plate, spraying a liquid on the surface of the upper heat transfer tube, and forming a liquid film on the surface of the lower heat transfer tube. In a heat exchanger in which heat is exchanged between the inner and outer surfaces of the heat transfer tubes by being dropped, heat transfer tubes whose ends are bent in front of a mounting portion of a tube plate are stacked in multiple stages, and the ends of the heat transfer tubes are inserted into the tube plate. Then, the end portions of the inserted heat transfer tubes are placed between the ends of the inserted heat transfer tubes in the upper stage, and the end portions of the inserted heat transfer tubes in the lower stage are located below the ends of the heat transfer tubes. This is achieved by arranging the ends of the heat pipes in a vertically shifted manner.

The purpose of the above is to insert the end of the horizontally arranged heat transfer tube into the tube sheet and expand the heat transfer tube. (3) In the heat exchanger, heat is exchanged between the inner and outer surfaces of the heat transfer tube by spraying the liquid on the surface of the upper heat transfer tube and dropping the liquid while forming a liquid film on the surface of the lower heat transfer tube. The end of the heat transfer tube has a shape bent horizontally in front of the tube sheet and obliquely to the tube sheet, and immediately before the tube sheet, bent again at a right angle to the tube sheet. The inserted heat transfer tubes are stacked in multiple stages, and the inserted heat transfer tube ends are located between the upper inserted heat transfer tube ends and the lower inserted heat transfer tubes below the heat transfer tube ends. The heat transfer tubes are arranged so that the ends are shifted from each other in the upper and lower stages so that the ends come to the end. Is arranged so that it is within the range.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of an embodiment of the heat exchanger according to the present invention.

FIG. 2 is a front view of the embodiment shown in FIG.

FIG. 3 is a partially enlarged view of the embodiment shown in FIG.

FIG. 4 is an explanatory view of the state of spraying liquid according to the prior art and the vertical spacing between heat transfer tubes.

FIG. 5 is an explanatory diagram of the state of spraying of the liquid and the vertical spacing between the heat transfer tubes in the embodiment shown in FIG.

FIG. 6 is a left side view of the embodiment shown in FIG.

FIG. 7 is a sectional view taken along line AA of the embodiment shown in FIG.

FIG. 8 is a plan view of another embodiment of the heat exchanger according to the present invention.

FIG. 9 is a plan view of still another embodiment of the heat exchanger according to the present invention. .

FIG. 10 is a cycle flow diagram of an absorption type water chiller / heater.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the main configuration and operation of the absorption chiller / heater will be described with reference to the flowchart of FIG. I do. Absorption chiller / heater includes high-temperature regenerator 301, low-temperature regenerator 302, condenser 303, evaporator 304, absorber 300, low-temperature heat exchanger 303, high-temperature heat exchange It comprises a vessel 307, a solution pump 308 for circulating the absorbed solution, and a pipe connecting these.

The operation during the cooling operation will be described. During cooling operation, it is heated by an external heat source to concentrate the solution in the high-temperature regenerator 301, and the refrigerant vapor generated by the heating is guided to the heat exchanger 302A in the low-temperature regenerator 302, and the low-temperature The solution in the regeneration 302 is heated and concentrated to generate a refrigerant vapor, and the introduced refrigerant vapor itself is condensed and liquefied and flows into the condenser 303. The refrigerant vapor generated in the low-temperature regenerator 302 is guided to the condenser 303, and the refrigerant vapor cooled by the cooling water is condensed and liquefied and sent to the evaporator 304. The liquid refrigerant in the evaporator 304 is pressure-fed by the refrigerant pump 309, and is sprayed to the heat exchanger 304A in the evaporator 304. The cold water flowing in the heat exchanger 304 A exchanges heat with the sprayed liquid refrigerant, and the liquid refrigerant evaporates and flows into the absorber 305. The chilled water that has entered through the chilled water inlet is cooled by the latent heat of vaporization at that time, and exits through the chilled water outlet and is supplied to the cooling water for cooling. The concentrated solution concentrated in the high-temperature regenerator 301 and the low-temperature regenerator 302 is sprayed to the heat exchanger 300A in the absorber 350, and cooled in the heat exchanger 300A. Cooled with water. The cooled concentrated solution absorbs the refrigerant vapor from the evaporator 304 and becomes a dilute solution. This dilute solution is divided into two by a solution pump 308 via a low-temperature heat exchanger 306, one of which is led to a low-temperature regenerator 302, and the other via a high-temperature heat exchanger 307. Then, it is led to the high-temperature regenerator 301.

The above cycle constitutes a cooling cycle.

Next, evaporator heat exchanger 304 A, absorber heat exchanger 300 A, low-temperature regenerator heat exchanger 302 A to promote evaporation and absorption of liquid sprayed from above The means for realizing the heat transfer tube group will be described.

FIG. 1 is a plan view of an embodiment of a meandering heat transfer tube group, in which a heat transfer tube 1 is bent horizontally in a hairpin shape, that is, in front of a tube sheet 2, and again immediately before a tube sheet 2. A heat exchanger tube 1 bent at a right angle to evaporator heat exchanger 304 A and absorber heat exchanger 304 A. In this embodiment, three heat transfer tubes 1 are used in parallel and bent.

FIG. 2 is a side view of FIG. 1, and according to the present embodiment, the hairpin-shaped heat transfer tubes 1 are stacked up and down in multiple stages, and the interval between the upper and lower heat transfer tubes 1 is smaller than that of the conventional one. Narrow) indicates that they can be stacked.

Fig. 3 is an enlarged view of the end of the heat transfer tube (part B surrounded by a circle) in Fig. 1. The end of the heat transfer tube is bent horizontally in front of the tube sheet and obliquely to the tube sheet. In addition, immediately before the tube sheet, heat transfer tubes bent at right angles to the tube sheet are stacked in multiple stages again, and each inserted heat transfer tube end portion is placed in the upper stage. The heat transfer tubes are arranged so that the heat transfer tube ends are shifted from each other in the upper and lower stages so that the lower end of the inserted heat transfer tube is located between the inserted heat transfer tube ends and below the heat transfer tube ends. are doing. That is, the positions of the first stage (solid line) and the second stage (two-dot chain line) are shifted as shown in the figure, and the third stage is bent at the same angle as the first stage (that is, the solid line). Furthermore, the fourth stage is bent and added to the same phase as the second stage (two-dot chain line). When bent in this manner, as shown in FIG. 5, the vertical distance C of the heat transfer tubes 1 in the expanded portion of the tube sheet 2 is changed to the vertical distance C of the conventional heat transfer tubes shown in FIG. The same spacing can be ensured, and sufficient plastic working allowance can be obtained. That is, the distance between the same longitudinal heat transfer tubes 1 is smaller than that of the conventional heat transfer tube while maintaining the same distance C.

Fig. 4 shows the situation of a conventional liquid 5 sprayed by the spraying device 4 when it flows down from the heat transfer tube 1 to the lower heat transfer tube 1 and travels down the heat transfer tube 1 by surface tension to form a liquid film. As can be seen from the figure, the flow width of liquid 6 is reduced as it travels downward.

In contrast, in the present embodiment shown in FIG. 5, the distance between the vertical heat transfer tubes 1 in the same row is small, and when the liquid flows down from the heat transfer tube 1 to the lower heat transfer tube 1, the liquid 5 Flow The heat transfer tube 6 spreads in the axial direction of the heat transfer tube due to the principle of the capillary tube effect, so that the surface of the heat transfer tube is well wetted over the entire surface and the heat transfer coefficient is improved.

FIG. 6 is a left side view of FIG. 2, and shows that the expanded portion of the tube sheet 2 can secure a plastic working allowance as in the conventional case.

FIG. 7 is a cross-sectional view taken along the line AA of FIG. 2, and shows that the heat transfer tubes 1 can be arranged with a small vertical space inside the shell 3. It also shows that the refrigerant vapor generated from the heat exchanger 304 A of the evaporator 304 flows into the heat exchanger 304 A of the absorber 304, and the heat transfer tube 1 and the heat transfer tube When the vertical interval of 1 is small, the refrigerant vapor easily flows in the vertical direction as indicated by the arrow in the figure. For this reason, the refrigerant vapor easily flows from the upper side to the lower side in the absorber 305, and the flow in the lateral direction is reduced, so that the evaporation and absorption performance can be exhibited more than before. Therefore, it is possible to realize a high-performance absorption and cooling water heater.

Next, FIG. 8 shows another embodiment. As in the embodiment shown in FIG. 1, the heat transfer tube 1 is formed in a serpentine shape, and the heat transfer tube groups arranged in a horizontal direction are vertically stacked in multiple stages, but the end is bent at 90 °. In addition, the bending position is different between the first stage (solid line) and the second stage (two-dot chain line), and the third stage is again bent at the same position as the first stage.

According to this embodiment, since it is not necessary to set different bending angles for the first and second bending angles, the bending process is easier than that of the embodiment shown in FIG. FIG. 9 shows still another embodiment.

Either heat of evaporator 304, evaporator heat exchanger 304A and absorber 300, absorber heat exchanger 304A and low temperature regenerator 302, low temperature regenerator 302a It may be an exchanger. Heat transfer tubes 10 of different diameters having different diameters at one end, the center and the other end are alternately arranged vertically, and there is no interval B in the heat transfer portion 1OA of the heat transfer tubes 10 or Construct heat transfer tube banks at small intervals ranging from l mm to 3 mm. Both ends of the heat transfer tube 10 of different diameter are slightly larger than the heat transfer portion 1 OA, and the end 10 8 is thicker and the end 10 is thinner than the heat transfer tube 1 OA. Consists of C. Both ends 10 B of the heat transfer tubes 10 of different diameters and IOC can secure the plastic working allowance A necessary for expanding the tube to the tube sheet 2.

According to this embodiment, it is not necessary to perform the bending process.

As described above, a plurality of meandering heat transfer tubes bent multiple times in the shape of a hairpin are bundled and horizontally arranged horizontally, and the vertical spacing between the heat transfer tubes is made as close as possible to zero, so that the liquid is discharged. In an evaporator that is sprayed from the top of the heat transfer tube group and evaporates, an absorber with absorption, and a low-temperature regenerator, the spread of liquid in the axial direction of the heat transfer tubes can be promoted, and the heat transfer coefficient can be improved.

In addition, by turning the heat transfer tubes inside the shell and letting the heat transfer tubes penetrate out of the shell only at the inlet and outlet of the cold and hot water and cooling water, the hot and cold water can also be used to shift the phase of the expanded section to the tube sheet. However, only the cooling water inlet / outlet can be provided.

Further, since the vertical distance between the heat transfer tubes is small, the height of the absorption chiller / heater can be made lower than before so that the whole can be made compact.

Claims

The scope of the claims

1. Insert the end of the heat transfer tube into the tube plate, adhere the heat transfer tube to the tube plate, spray the liquid on the surface of the upper heat transfer tube, and drop it while forming a liquid film on the surface of the lower heat transfer tube. In the heat exchanger where heat is exchanged between the inner and outer surfaces of the heat transfer tube by

The heat transfer tubes whose ends were bent in front of the mounting portion of the tube sheet were stacked in multiple stages, the ends of the heat transfer tubes were inserted into the tube sheet, and the inserted end portions of the heat transfer tubes were inserted in the upper stage. The heat transfer tube ends are shifted from each other in upper and lower stages so that the lower end of the inserted heat transfer tube is located between the heat transfer tube ends and below the heat transfer tube ends. Heat exchanger.

2. Insert the end of the heat transfer tube into the tube sheet, adhere the heat transfer tube to the tube plate, spray the liquid on the surface of the upper heat transfer tube, and drop it while forming a liquid film on the surface of the lower heat transfer tube. In the heat exchanger where heat is exchanged on the outer surface of the heat transfer tube by

The end of the heat transfer tube has a shape which is bent horizontally in front of the tube sheet and obliquely with respect to the tube sheet, and immediately before the tube sheet, again bent at a right angle to the tube sheet. The inserted heat transfer tubes are stacked in multiple stages, and the inserted heat transfer tube ends are between the upper inserted heat transfer tube ends and the lower inserted heat transfer tube ends below the heat transfer tube ends. A heat exchanger characterized in that the heat transfer tube ends are displaced from each other in the upper and lower stages so that the heat exchanger tubes come into contact.

3. The heat exchanger according to claim 2,

The heat exchanger is characterized in that the heat transfer tubes are inserted into the same tube plate at both ends, expanded and adhered to each other, and the heat transfer portion between both ends has a meandering shape.

4. The heat exchanger according to claim 3,

A heat exchanger characterized in that the heat transfer tubes are arranged so that a distance between upper and lower tiers in a heat transfer portion of the heat transfer tubes between opposed tube sheets is in a range of 1 mm to 3 mm.

5. Insert the end of the heat transfer tube into the tube sheet, adhere the heat transfer tube to the tube plate, spray the liquid on the surface of the upper heat transfer tube, and drop it while forming a liquid film on the surface of the lower heat transfer tube. To Therefore, in a heat exchanger in which heat is exchanged between the inner and outer surfaces of the heat transfer tube,

Heat transfer tubes with the heat transfer tube end horizontally bent in front of the tube sheet and bent at right angles to the tube sheet are stacked in multiple stages, and each inserted heat transfer tube end is inserted into the upper stage. The heat transfer tube ends are shifted up and down so that the lower end of the inserted heat transfer tube is located between the heat transfer tube ends and below the heat transfer tube end. A heat exchanger.

6. The heat exchanger according to claim 5,

A heat exchanger wherein both ends of a heat transfer tube are inserted into and adhere to different tube sheets facing each other, and a heat transfer portion between both ends has a meandering shape.

7. Insert the end of the heat transfer tube into the tube plate, adhere the heat transfer tube to the tube plate, spray the liquid on the surface of the upper heat transfer tube, and drop it while forming a liquid film on the surface of the lower heat transfer tube. In the heat exchanger where heat is exchanged between the inner and outer surfaces of the heat transfer tube by

Stacked straight heat transfer tubes with a small diameter portion and a large diameter portion with different diameters at one end from the multi-end, and the small diameter portion and the large diameter portion of the heat transfer tube alternate in the upper and lower stages and the left and right stages, respectively. A heat exchanger characterized in that the heat exchanger is arranged and inserted into a tube sheet.

8. Insert the end of the horizontally arranged heat transfer tube into the tube sheet, expand the heat transfer tube and make it tightly adhere to the tube plate, spray the liquid on the surface of the upper heat transfer tube, and apply the liquid film on the surface of the lower heat transfer tube. In the heat exchanger where heat is exchanged between the inner and outer surfaces of the heat transfer tube by dropping while forming the heat transfer tube, the heat transfer tube end is bent horizontally in front of the tube sheet and obliquely to the tube sheet Immediately before the tube sheet, heat transfer tubes bent at right angles to the tube sheet are stacked in multiple stages again, and the end portions of the inserted heat transfer tubes are inserted in the upper stage. The heat transfer tubes are arranged so that the heat transfer tube ends are displaced from each other in the upper and lower stages so that the lower end of the inserted heat transfer tube is located between the heat tube ends and below the heat transfer tube ends. The distance between the upper and lower tiers of the heat transfer tube between the Heat exchanger, characterized in that arranged so as to enclose.

9. In an absorption chiller / heater equipped with an evaporator and an absorber, The heat transfer tubes whose ends are bent in front of the mounting portion of the tube sheet are stacked in multiple stages, and the ends of the heat transfer tubes are inserted into the tube sheet, and the inserted end portions of the heat transfer tubes are inserted into the upper stage. The heat transfer tube ends are shifted from each other in the upper and lower stages so that the lower end of the inserted heat transfer tube is located between the heat transfer tube ends and below the heat transfer tube end. An absorption chiller / heater, wherein an exchanger is used for at least one of the evaporator and the absorber.

10 In an absorption chiller / heater equipped with an evaporator and an absorber,

Heat transfer tubes with the heat transfer tube end horizontally bent in front of the tube sheet and bent at right angles to the tube sheet are stacked in multiple stages, and each inserted heat transfer tube end is inserted into the upper stage. The heat transfer tubes are arranged with the heat transfer tube ends shifted up and down so that the lower end of the inserted heat transfer tube is located between the heat transfer tube ends and below the heat transfer tube end. Absorption type chiller / heater characterized by using a heat exchanger constituted by:

1 1. In an absorption type chiller / heater equipped with an evaporator and an absorber,

Stacked straight heat transfer tubes with a small diameter portion and a large diameter portion with different diameters at one end from the multi-end, and the small diameter portion and the large diameter portion of the heat transfer tube alternate in the upper and lower stages and the left and right stages, respectively. The heat exchanger is constructed by stacking heat transfer tubes at right angles to the tube sheet in parallel in multiple stages and inserting each end of the heat transfer tubes into the tube sheet. And an absorption type chiller / heater used for at least one of an absorber and an absorber.