JPH0518632A - Absorption refrigerating apparatus - Google Patents

Abstract

PURPOSE:To improve refrigerant steam absorbing capacity of an absorber and to improve the operation efficiency of an absorption CONSTITUTION:A plurality of protrusions 32 are longitudinally formed on the outer surface of a pipe and a crest part 33 of the protrusion 32 and a root part 34 between the adjoining protrusions 32 and 32 form a curved surface. The curvature of radius of the root part 34 is increased to a value higher than that of the crest part 33. An absorption type freezer is provided with an absorber 3 having heat transfer pipes 31 wherein a lean solution dripped on the outer surface of the pipe is cooled by cooling water flowing through the pipes. The lean solution dripped on the heat transfer pipe 31 smoothly flows from the root part 34 over the crest part 33 to the next root part 34, and the lean solution is smoothly replaced at the root part 34. The lean solution approximately uniformly flows throughout the whole periphery of the heat transfer pipe 31. Further, Marangoni convection generated at the crest part 33 and that at the root part 34 are interfered with each other and high agitation operation is generated in the axial direction of the pipe. The heat exchange efficiency of the heat transfer pipe 31 is sharply improved. Absorbing capacity of refrigerant steam of the absorber 3 is improved, and the operation efficiency of an absorption type freezer is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigerating machine in which an absorber having a plurality of absorber heat transfer tubes is connected by piping.

[0002]

2. Description of the Related Art For example, Japanese Patent Laid-Open No. 58-200995 discloses a heat transfer tube in which a plurality of ridges are formed in the longitudinal direction on the outer surface of the pipe, and the peaks of the ridges and the valleys between the ridges are curved. Is disclosed.

Further, for example, in Japanese Utility Model Laid-Open No. 61-49267, the concentrated absorbing liquid is subdivided into small pieces between cooling water heat exchangers which are housed in an absorber and are composed of a plurality of heat transfer tubes having smooth outer surfaces. An absorption refrigerator provided with a demister for making particles is disclosed.

[0004]

In the above conventional technique, when the ridges and the valleys of the ridges have substantially the same radius of curvature and the valleys have a small radius of curvature, the absorbing liquid in the valleys is adjacent to each other. Since it is difficult to move to the valley portion, the heat exchange efficiency on the outer surface of the heat transfer tube decreases, and the ability to absorb the refrigerant vapor from the evaporator of the absorber decreases. As a result, the generation of refrigerant vapor in the evaporator is suppressed, and the cooling capacity is reduced, which may reduce the operating efficiency.

Further, when the outer surface of each heat transfer tube is smooth, the absorbing liquid is offset by the surface tension and drops downward, so that the heat exchange efficiency on the outer surface of each heat transfer tube decreases. Therefore, in order to improve the heat exchange efficiency, it is necessary to provide, for example, a demister between each heat transfer tube, which causes a problem that the absorber becomes large and the absorption refrigerator becomes large. Further, each demister may become a resistance to the flow of the refrigerant vapor from the evaporator, the absorption capacity of the refrigerant vapor in the absorber may be reduced, the cooling capacity may be reduced, and the operation efficiency may be reduced.

An object of the present invention is to improve the absorption capacity of the refrigerant vapor of the absorber and improve the operation efficiency of the absorption refrigerator.

[0007]

In order to solve the above problems, the present invention solves the above problems by using an absorber 3, a high temperature regenerator 4 and a low temperature regenerator 1.
1. In an absorption chiller in which a condenser 12 and an evaporator 2 are connected by piping to form a refrigeration cycle, a plurality of protrusions 32 are formed in the longitudinal direction on the outer surface of the pipe, and the protrusions 32 of the protrusions 32 and adjacent portions are formed. The valley portion 34 between the fitted ridges 32, 32 is formed into a curved surface, and the radius of curvature of the valley portion 34 is made larger than the radius of curvature of the mountain portion 33, so that the absorbing liquid from the low temperature regenerator 11 drops on the outer surface of the tube. Alternatively, the absorption type refrigerator provided with the absorber 3 having the absorber heat transfer pipe 31 that is sprayed and cools the absorption liquid outside the pipe by the cooling water inside the pipe is provided, and the absorption capacity of the refrigerant vapor of the absorber 3 is improved. Then, the refrigerant vapor generation amount of the evaporator 2 is increased, and the operation efficiency of the absorption refrigerator is improved.

Further, a plurality of ridges 37 having a twist angle of 15 ° or less are provided on the outer surface of the tube to give a continuous curved surface shape, and the radius of curvature R ₁ of the peak 38 and the radius of curvature of the valley 40 are provided. Provided is an absorption refrigerator having an absorber 3 accommodating a heat transfer tube 36 in which R ₂ and the ratio R ₂ / R ₁ are formed to be greater than 1, thereby improving the wettability of each heat transfer tube. Even when the absorber 3 is upsized, the absorption capacity of the refrigerant vapor is improved, and the operation efficiency of the absorption refrigerator is improved.

The upper heat transfer tube 31 and the lower heat transfer tube 31
And a plurality of ridges 37 having a twist angle of 15 ° or less are formed on the outer surface of the pipe, and the peaks 38 and the valleys 4 of the ridges 37 are formed.
Provided is an absorption refrigerator having an absorber in which 0 is a curved surface and the radius of curvature of the valley portion 40 is larger than the radius of curvature of the mountain portion 38, and the absorbing liquid is evenly distributed to the heat transfer pipe 31. It is added dropwise to improve the operation efficiency.

Further, a pair of tube sheets 1A, 1A, a tube support plate 36, and a plurality of ridges 32 are formed on the outer surface of the tube, and the radius of curvature of the valley portion 34 is made larger than that of the mountain portion 33. Further, an absorption refrigerator having an absorber provided with a heat transfer tube 31 having tube plate support portions 31A and 31A having a smooth tube outer surface and a tube support support portion 31B is provided, and operation of the absorption refrigerator is provided. In addition to improving efficiency, the heat transfer tube 31 is attached to the tube plate support portion
A, 31A and the pipe support portion 31B are reliably supported.

Further, the height of the ridge 32 is set to the tube plate supporting portion 31A,
31A and the pipe support portion 31B are gradually lowered,
The cracks at the ends of the peaks 33 and the valleys 34 are avoided.

[0012]

The concentrated absorbing liquid dropped into the heat transfer tube 31 smoothly flows from the valley portion 34 having a larger radius of curvature than the peak portion 33 to the next valley portion 34 over the peak portion 33, so that the absorbing liquid in the valley portion 34 is Are smoothly exchanged, the concentrated absorbent flows almost uniformly over the entire circumference of the heat transfer tube 31, and the Marangoni convections generated in the crests 33 and the valleys 34 interfere with each other, so that the tube axis A large disturbance action occurs in the direction, the heat exchange efficiency in the heat transfer tube 31 is significantly improved,
Heat transfer tube 3 for concentrated absorbing liquid whose temperature has risen by absorbing refrigerant vapor
1, the cooling capacity is improved, the absorption capacity of the refrigerant vapor by the concentrated absorbing liquid is recovered, the absorption amount of the refrigerant vapor is increased, and the evaporator 2
The cooling capacity can be improved, and the operation efficiency of the absorption refrigerator can be improved.

Further, the concentrated absorbent flows more smoothly over the ridges 38 of the projections 37 formed on the outer surface of the heat transfer tube 36 and forming a twist angle, and the concentrated absorbent moves in the axial direction of the tube. The heat transfer tube 3 is dropped by dropping it into the heat transfer tube 31 below while flowing.
The wettability of No. 1 is improved, the cooling capacity of the heat transfer tube 31 is further improved, the absorption capacity of the refrigerant vapor of the absorber is improved, and the operation efficiency of the absorption chiller can be improved.

Further, the absorbing liquid dripping from the upper heat-transfer tube 31 to the heat-transfer tube 36 is offset and flows along the outer surface of the heat-transfer tube 36 along the twisting direction, so that the absorbing liquid is transferred from the lower end of the heat-transfer tube 36 almost uniformly to the lower-step. Drops on the heat pipe 31 and flows evenly on the outer surface of the pipe,
It is possible to improve the heat transfer performance of the heat transfer tube 31, improve the absorption capacity of the refrigerant vapor of the absorber, and improve the operation efficiency of the absorption refrigerator.

Further, by supporting the heat transfer tube 31 by the tube sheet support portions 31A, 31A and the tube support support portion 31B,
The heat transfer tube 31 is surely supported, and the tube plate support portion 31
It becomes possible to ensure the seal between A, 31A and the tube sheet 1A, 1A, and by gradually lowering the height of the ridge 32, cracks at the ends of the peaks 33 and valleys 34 Can be avoided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes an evaporative absorber cylinder (lower cylinder), and an evaporator 2 and an absorber 3 are housed in the evaporative absorber cylinder 1. Reference numeral 4 denotes a high temperature regenerator equipped with a gas burner 5, for example, a first absorbent pump P and a low temperature heat exchanger 7 in the middle of the dilute absorbent liquid pipe 6 from the absorbent reservoir 3A of the absorber 3 to the high temperature regenerator 4. And a high temperature heat exchanger 8 are provided.

Reference numeral 10 denotes a high-temperature cylinder (upper cylinder), in which the low-temperature regenerator 11 and the condenser 12 are housed. Further, 13 is a refrigerant vapor pipe from the high temperature regenerator 4 to the low temperature regenerator 11, 14 is a heater provided in the low temperature regenerator 11, and 15 is a refrigerant pipe from the heater 14 to the condenser 12. Reference numeral 16 is a refrigerant liquid flow-down pipe from the condenser 12 to the evaporator 2, 17 is a refrigerant circulation pipe connected to the evaporator 2 by piping, 18
Is a refrigerant pump. Reference numeral 21 is a cold water pipe connected to the evaporator 2, and 21A is an evaporator heat exchanger.

Reference numeral 22 is an intermediate absorption liquid pipe from the high temperature regenerator 4 to the high temperature heat exchanger 8, 23 is an intermediate absorption liquid pipe from the high temperature heat exchanger 8 to the low temperature regenerator 11, 23A is an inlet of the intermediate absorption liquid, Reference numeral 24 is a second absorption liquid pump provided in the intermediate absorption liquid pipe 23. 25 is the low temperature regenerator 11 to the low temperature heat exchanger 7
The concentrated absorption liquid pipe to 26, the low temperature heat exchanger 7 to the absorber 3
And 27 is a concentrated absorbent return pipe (bypass pipe) from the concentrated absorbent pipe 25 to the intermediate absorbent liquid pipe 23 on the inlet side of the second absorbent pump 24. Further, 28 is a damper provided in the concentrated absorbent return pipe 26. Further, 29 is a cooling water pipe, 29A is an absorber heat exchanger, 29B is a condenser heat exchanger, and 30 is a concentrated absorbent dispersion device provided above the absorber heat exchanger 29A.

The absorber heat exchanger 29A has a plurality of stages arranged substantially horizontally.
The heat transfer tubes 31 are arranged in a plurality of rows. The heat transfer tube 31 has a circular shape and the diameter is equal over the entire length, for example, 16 mm. Further, as shown in FIGS. 2 to 4, a plurality of protrusions 32 are formed on the outer surface of the heat transfer tube 31 in the longitudinal direction, that is, the tube axis direction. Where the ridge 32
Number of 4 to 16 Then, the ridges 33 of each ridge 32, and the valley 34 between the adjacent ridges 32, 32.
Each has a curved shape. And Yamabe 33 ...
The radius of curvature R ₁ is for example 1.0mm, the troughs 34 ... is, for example 1.5mm radius of curvature R ₂ of crest 33 ... valley 34 ... curvature radius of larger than, the R ₂ / R ₁ The heat transfer tube is made larger than 1. Where R ₂ /
R ₁ is smaller than 4. Also, the height of each protrusion 32 (H)
Is 1.0 mm or less, for example, 0.7 mm, and the distance between the protrusions 32 is, for example, about 4 mm.
1 has been created.

Further, as shown in FIG. 3, at both ends of the heat transfer tube 31, a tube plate supporting portion (expanding portion) 31 having a smooth outer tube surface is provided.
A and 31A are formed, and these tube plate support portions 31A and 31A are formed.
A is supported by penetrating through the support holes 1a, 1a of the tube plates 1A, 1A of the cold cylinder 1. Also, the middle part (center) of the heat transfer tube 31
A pipe supporting and supporting portion 1B is formed on the outer surface of the pipe so as to be smooth, and the pipe supporting and supporting portion 31B is supported by penetrating the supporting hole 1b of the supporting plate 1B. In addition, the height of the ridge 32 of the heat transfer tube 31 is such that the tube plate support portions 31A and 31A and the tube support support portion 31B.
The incomplete ridge portion 31C gradually lowers to 10 mm
Formed to 50 mm.

During operation of the absorption refrigerator constructed as described above, the gas burner 5 of the high temperature regenerator 4 burns, and the absorber 3
The rare absorption liquid, such as an aqueous solution of lithium bromide (LiBr) (containing a surfactant), flowing from the above is heated, and the refrigerant vapor is separated from the rare absorption liquid. Refrigerant vapor is refrigerant vapor pipe 1
It flows to the low temperature regenerator 11 via 3. Then, the refrigerant liquid obtained by heating and condensing the intermediate absorption liquid from the high temperature regenerator 4 in the low temperature regenerator 11 flows into the condenser 12. In the condenser 12, the refrigerant vapor flowing from the low temperature regenerator 11 is condensed and flows down to the evaporator 2 together with the refrigerant liquid flowing from the low temperature regenerator 11. In the evaporator 2, the refrigerant liquid is sprayed to the evaporator heat exchanger 21A by the operation of the refrigerant pump 18. Then, cold water that has been cooled by the evaporator heat exchanger 21A and has its temperature lowered is supplied to the load. The refrigerant vapor vaporized in the evaporator 2 flows to the absorber 3 and is absorbed by the concentrated absorbing liquid sprinkled on the absorber heat exchanger 29A.

The intermediate absorption liquid whose concentration is increased by separating the refrigerant vapor in the high temperature regenerator 4 passes through the intermediate absorption liquid pipe 22, the high temperature heat exchanger 8, the intermediate absorption liquid pipe 23 and the second absorption liquid pump 24 and is regenerated at low temperature. It flows to the vessel 11.

The intermediate absorbing liquid is heated by the heater 14 in which the refrigerant vapor from the high temperature regenerator 4 flows. Then, the refrigerant vapor is separated from the intermediate absorption liquid, and the concentration of the absorption liquid is further increased.

The concentrated absorption liquid heated and condensed in the low temperature regenerator 11 flows into the concentrated absorption liquid pipe 25, flows through the low temperature heat exchanger 7 and the concentrated absorption liquid pipe 26 into the absorber 3, and the concentrated absorption liquid spraying device ( (Hereinafter referred to as a spraying device) 30 to the absorber heat exchanger 29A. Then, when the concentrated absorbent drips onto the heat transfer tube 31 of the absorber heat exchanger 29A, the concentrated absorbent smoothly flows over the outer surface of the heat transfer tube 31 over the ridges 33 ... In each of the valleys 34, Marangoni convection, that is, a concentration distribution on the surface of the liquid film of the surfactant causes a difference in surface tension, which causes tension convection. That is, as shown in FIG. 5, the thickness (ΔH) of the liquid film becomes thicker in each valley portion 34.
Marangoni convection in the tube axis direction becomes stronger. In addition, each mountain part 3
In 3 ..., the thickness (Δh) of the liquid film becomes thin, and Marangoni convection in the tube axis direction becomes weak. Then, the Marangoni convections of the mountain portions 33 and the valley portions 34 interfere with each other, and a large disturbing action occurs in the axial direction of the tube.

Further, the radius of curvature of the valleys 34 ...
The radius of curvature is larger than the radius of curvature of the valleys 34, and the valleys 34 have a gentle curved surface shape, the replacement of the concentrated absorbing liquid in the valleys 34 becomes faster, and the movement of the concentrated absorbing liquid on the outer surface of the heat transfer tubes 31. Get faster Then, Marangoni convection is generated substantially uniformly over the entire circumference of the heat transfer tubes 31 .... Therefore, each heat transfer tube 31
The amount of heat exchange in the ... increases, and the concentrated absorbing liquid flowing on the outer surface of the heat transfer tube 31 is cooled. Then, from the evaporator 2 to the absorber 3
The refrigerant vapor flowing in is absorbed by the concentrated absorbing liquid flowing on the outer surface of the heat transfer tube 31. The absorption liquid (rare absorption liquid), which has absorbed the concentrated absorption liquid and becomes thin in concentration, is sent to the high temperature regenerator 4 by the operation of the first absorption liquid pump P.

According to the above-mentioned embodiment, when the concentrated absorbent flowing from the low temperature regenerator 11 is dropped onto the heat transfer tubes 31, the valley on the outer surface of the tube has a larger radius of curvature than the peaks 33.
4 smoothly flows to the next troughs 34 over the curved peaks 33 ..., so that the absorption liquid is smoothly exchanged in the troughs 34 and the absorption liquid is transferred to the heat transfer tube 3
1 can be flowed uniformly over the entire circumference, and the mountain portion 33
... and the Marangoni convections generated in the troughs 34 interfere with each other to generate a large disturbing action in the axial direction of the tube, and the heat exchange efficiency in the heat transfer tubes 31 can be significantly improved. For this reason, it is possible to improve the cooling capacity of the heat transfer tube 31 for absorbing liquid whose temperature has risen due to absorption of the refrigerant vapor while flowing on the outer surface of the heat transfer tube 31, and to recover the refrigerant vapor absorption capacity. Therefore, the absorption amount of the refrigerant vapor in the absorber 3 increases, the generation amount of the refrigerant vapor in the evaporator 2 increases, and as a result, the cooling capacity in the evaporator 2 can be improved, and the absorption refrigeration The operating efficiency of the machine can be improved.

Further, by forming the inner surface of the pipe into a curved surface corresponding to the outer surface of the pipe, it is possible to prevent the scale from adhering to the inner surface of the cooling water in the cooling water and to easily clean the inside of the pipe. As a result, the maintenance and inspection work of the absorption refrigerator can be simplified.

Further, when the height of the protrusions 32 is made larger than 1.5 mm, the absorbing liquid dripping outside the heat transfer pipes 31 is likely to stay in the valleys 34, and the replacement of the absorbing liquid is smooth. The height of the ridge is 1.5m.
It is desirable to be less than or equal to m.

Further, since the heat transfer tube 31 is formed with the tube plate support portions 31A, 31A and the tube support support portion 31B whose outer surfaces are smoothed, the heat transfer tube 31 is connected to the tube plates 1A, 1A and the support plate 1B. Tube plate support portions 31A, 31A and tube support support portion 31
It can be reliably supported by B, and tube sheets 1A, 1A
The tube sheet support portions 31A and 31A can be reliably sealed by expanding the tube. Further, since the height of the ridge 32 is gradually reduced, it is possible to avoid the occurrence of cracks at the ends of the peaks 33 and the valleys 34.

A second embodiment of the present invention will be described below with reference to the drawings. In FIGS. 6 and 7, the same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 6, reference numeral 35 is an absorber heat exchanger provided below the spraying device 30 of the absorber 3. The absorber heat exchanger 35 is composed of a heat transfer tube group including a plurality of stages and a plurality of rows of heat transfer tubes 36, as in the first embodiment. The outer surface of the heat transfer tube 36 has a twist angle α of 15 ° or less in the longitudinal direction, that is, the tube axis direction, as shown in FIG. 7.
(About 5 ° in the drawing), and a plurality of ridges 37 are formed in the pipe axis direction. Moreover, each of these ridges 37
The mountain portion 38 and the valley portion 4 between the adjacent ridges 37, 37.
Each 0 has a curved surface shape. And Yamabe 38
Has a radius of curvature of, for example, 1.0 mm, the valley portion 40 has a radius of curvature of, for example, 1.5 mm, and the heat transfer tube 36 is formed so that the radius of curvature of the valley portion 40 is larger than that of the mountain portion 38.
Further, the height of each protrusion 37 is 1.5 mm or less, for example, 0.
7 mm, and the distance between the protrusions 2 is, for example, about 4 mm.
The heat transfer tube 1 is formed so that. The twist angle is, for example, 5 °.

During operation of the absorption refrigerator having the absorber constructed as described above, the absorbing liquid and the refrigerant circulate as in the absorption refrigerator shown in the first embodiment. Then, the concentrated absorbing liquid flowing from the low temperature regenerator is dropped from the spraying device 30 to the heat transfer tube 36. The concentrated absorbent smoothly flows over the outer surface of the heat transfer tube 36 over the peaks 38 of the protrusions 37, and the valleys 40
Thus, due to Marangoni convection, that is, the concentration distribution of the surfactant on the liquid film surface, a difference in surface tension is generated, which causes tension convection.

That is, as in the first embodiment, each trough 4 is formed.
At 0, Marangoni convection in the tube axis direction becomes stronger, and
The Marangoni convection in the tube axis direction is weakened in each mountain portion 38. For this reason, the Marangoni convection of the peaks 38 and the valleys 40 interferes with each other, and a large disturbing action occurs in the axial direction of the tube.

Further, since the ridge 37 has a twist angle, the concentrated absorbing liquid flows down along the twist angle. For this reason,
Since the absorbing liquid does not get wet and unevenly flow over the entire length of the heat transfer tubes 36 in each stage, uniform Marangoni convection is generated over the entire tube group.

When the heat transfer tubes 36 flow down the outer surface as described above, the concentrated absorbing liquid absorbs the refrigerant vapor flowing from the evaporator 2, and the concentration of the absorbing liquid dropped to the lower heat transfer tubes 36 is higher. Becomes thin. Then, the rare absorption liquid accumulated in the absorption liquid reservoir 3A of the absorber 3 is sent to the high temperature regenerator 4.

According to the above-described embodiment, the concentrated absorbing liquid dropped on the outer surface of the heat transfer tube 36 passes from the trough 40 having a larger radius of curvature than the trough 38 to the trough 38 formed on the curved surface to the next trough. 40, and the absorption liquid in the valley portion 40 is replaced more smoothly due to the twist angle, and the absorption liquid is made to flow evenly over the entire circumference of the heat transfer pipe 36 so that the entire pipe group The wettability can be improved, and the mountain portion 3
8 and the Marangoni convections generated in the troughs 40 interfere with each other to generate a large disturbing action in the tube axis direction, and the heat exchange efficiency in the heat transfer tubes 36, that is, the heat transfer performance can be significantly improved. As a result, it is possible to more efficiently cool the absorbing liquid that has absorbed the refrigerant vapor and whose temperature has risen, and to recover the refrigerant vapor absorption capacity, so that the absorption amount of the refrigerant vapor in the absorber 3 increases and the absorber 3 can be improved in performance, the amount of refrigerant vapor generated in the evaporator 2 can be increased, and the operation efficiency of the absorption refrigerator can be improved.

Here, the heat transfer performance of the heat transfer tube 36 changes as shown in FIG. FIG. 8 shows the amount of heat exchange when the aqueous solution of lithium bromide is sprayed at a flow rate of 0.66 Kg / ms, and the amount of heat exchange was 43 KW in the prior art, but 45 KW in the present invention. Therefore, the heat exchange amount increases by almost 5%.

A third embodiment of the present invention will be described below with reference to the drawings. In FIGS. 9 and 10, the same components as those in the first and second embodiments are designated by the same reference numerals and detailed description thereof will be omitted.

Reference numeral 41 is an absorber heat exchanger provided below the spraying device 30. The absorber heat exchanger 41 includes an upper heat transfer tube group 42, a lower heat transfer tube group 43, and these heat transfer tube groups 4
The heat transfer tube 36 is provided between the heat transfer tube group 2 and the heat transfer tube group 43 in one stage, for example. The heat transfer tube group 42 and the heat transfer tube group 43 are each composed of a plurality of stages and a plurality of rows of heat transfer tubes 31.

During operation of the absorption refrigerator having the absorber configured as described above, the absorbing liquid and the refrigerant circulate as in the absorption refrigerator shown in the first embodiment. Then, the concentrated absorbent flowing from the low temperature regenerator is dropped from the spraying device 30 to the heat transfer tubes 31 of the heat transfer tube group 42. The concentrated absorbing liquid dropped on the heat transfer tubes 31 flows over the outer surface of the heat transfer tubes 31 over the peaks 33 of the protrusions 32. Then, Marangoni convection occurs in each valley 34, and heat exchange between the cooling water flowing in the heat transfer tube 31 and the absorbing liquid is promoted. The concentrated absorbing liquid that has flowed on the outer surface of the heat transfer tube 31 and has reached the lower end is substantially evenly dropped to the heat transfer tube 31 in the lower stage.
The concentrated absorbent drops into the liquid and absorbs the refrigerant vapor during this period, so that the concentration gradually decreases. As described above, when the concentrated absorbing liquid is dripping, for example, the absorption refrigerator is large, the absorber is large, and the length of each heat transfer pipe 31, ... When a part (for example, right part) of the heat pipe 31 is curved downward even slightly, the concentrated absorbent flowing on the outer surface of the heat transfer pipe 31 flows toward the right part. For this reason, the amount of the concentrated absorbing liquid dripping from the right part of the heat transfer tube 31 is larger than that of the other part, that is, the central part and the left part, and
Also in the lower heat transfer tube 31, the amount of the concentrated absorbent dropped from the upper portion to the right portion is large, so that the amount of the concentrated absorbent dropped from the right portion is larger than the other portions.

Similarly, in the absorbing liquid dropped from the upper heat transfer tube 31 to the intermediate heat transfer tube 36, the right part of the heat transfer tube 36 is large and the left part and the center part are small. Here, unlike the heat transfer tube 31 in the upper stage, a plurality of ridges 37 having a helix angle are formed on the outer surface of the heat transfer tube 36 as shown in FIG.
8 and the valley portion 40 also have the same helix angle as the ridge 37, the absorbing liquid dropped to the left portion of the heat transfer tube 36 is
8 and the valley portion 40 to flow to the right and central portions of the heat transfer tube 36. Here, since the front and back of the heat transfer tube 36 have different twisting directions, the absorbing liquid that has dripped on the right part of the heat transfer tube 36 flows to a portion with a small drip amount, and the absorbing liquid is almost even from the lower end of the heat transfer tube 36. Drop on. In the lower heat transfer tube 31 of the heat transfer tube 36, the absorbing liquid flows almost uniformly on the outer surface, and the absorbing liquid drops substantially uniformly into the lower heat transfer tube 31. Hereinafter, similarly, in each heat transfer tube 31, the absorbing liquid flows almost uniformly on the outer surface, and in the meantime, it absorbs the refrigerant vapor and becomes thin, and the heat transfer tube 31 in the lowermost stage becomes thin.
Is dripped into the absorbing liquid reservoir 3A. And the absorption liquid pool 3
The rare absorbent of A is sent to the high temperature regenerator 4.

According to the above-described embodiment, the heat transfer tube 31 above the intermediate heat transfer tube 36 is, for example, slightly curved and partly bent downward, and the absorbing liquid gathers in that part, and the bent part bends downward. When the amount of the absorbing liquid to be dripped becomes large, a plurality of ridges 37 having a helix angle are formed on the outer surface of the heat transfer tube 36 at the intermediate stage. The absorption liquid is dripped almost uniformly by being guided by the ridges 38 and the troughs 40 of 37 to flow into and disperse in a portion where the dripping amount is small.
Then, the absorbing liquid flows substantially evenly on the outer surface of each heat transfer tube 31 below the heat transfer tube 36, and the heat transfer performance of the heat transfer tube 31 can be improved. As a result, the heat transfer tube 31 is bent. Also in this case, the absorption liquid that has absorbed the refrigerant vapor and whose temperature has risen can be cooled by each heat transfer tube 31 to recover the absorption capacity of the refrigerant vapor, and the absorption amount of the refrigerant vapor in the absorber 3 increases. As a result, the performance of the absorber 3 can be improved, and the operating capacity of the absorption refrigerator can be improved.

Further, since the heat transfer tube 36 having a helix angle is used in the middle stage and the heat transfer tubes 31 having no helix angle are used in the upper and lower heat transfer tubes, the heat transfer tube of the absorber 3 is used. The heat transfer tube cost can be significantly reduced as compared with the case where all the heat transfer tubes having a twist angle are used. Further, even if the outer surface of each heat transfer tube 31 is smooth, the heat transfer performance of the absorber can be improved by providing the heat transfer tube 36 in the intermediate stage, and the operation efficiency of the absorption chiller can be improved. You can

Further, from the absorber shown in FIG.
When there are a large number of stages (for example, 40 or more), the heat transfer tubes 36 having a helix angle are arranged at positions corresponding to, for example, 1/3 and 2/3 of the total number of stages. Therefore, similarly to the above-described embodiment, even when the amount of the absorbing liquid dripping from the upper heat transfer tube 31 of each heat transfer tube 36 becomes large in the central portion of the heat transfer tube 31, etc. The absorbing solution can be dripped almost uniformly into 31, and the same effect as that of the above embodiment can be obtained. Further, when the number of stages of the heat transfer tube 31 is further increased, the number of stages where the heat transfer tube 36 is provided is increased to, for example, 1/4, 1/2, 3/4 of the total number of stages. The effect of can be obtained. Further, when the outer surface of the heat transfer tube 31 is smooth and the number of stages of the heat transfer tube is large, the heat transfer tubes 36 are provided at a plurality of locations as described above.
The same effect can be obtained by providing.

[0045]

The present invention is an absorption refrigerator having the above-described structure, in which the peaks of the projections formed in the longitudinal direction on the outer surface of the pipe and the valleys between the adjacent projections are curved surfaces. In addition, since an absorber having a heat transfer tube for the absorber in which the radius of curvature of the valley is larger than the radius of curvature of the peak is provided, the absorbing liquid dropped on the outer surface of the heat transfer tube crosses the valley from the valley. It smoothly flows to the next trough, the replacement of the absorbing liquid in the trough is performed smoothly, the absorbing liquid can be evenly flowed over the entire circumference of the heat transfer tube, and it also occurs in the trough and the peak. Marangoni convection interferes with each other to generate a strong disturbing action in the axial direction of the tube, improving the heat exchange rate in the heat transfer tube, that is, the heat transfer performance, and improving the absorption capacity of the refrigerant vapor in the absorber. , The amount of refrigerant vapor generated in the evaporator is increased, the cooling capacity is improved, and the operation efficiency of the absorption chiller is improved. It is possible to improve.

Further, a plurality of ridges having a twist angle of 15 ° or less are formed on the outer surface of the pipe, and the ratio R ₂ / R _{1 of the} radius of curvature R ₁ of the crests to the radius of curvature R ₂ of the valleys is Since it is equipped with an absorber that accommodates the heat transfer tubes for absorbers that are formed to be larger than 1, the absorbing liquid smoothly flows from the trough to the next trough over the trough, and The replacement is performed smoothly, and the Marangoni convection generated in the valley and the peak interferes with each other to generate a strong disturbing action in the axial direction of the pipe. While flowing in the direction, it can flow down to the lower heat transfer tube and improve the wettability of the heat transfer tube. As a result, the cooling capacity in the evaporator is improved, and the absorption chiller It is possible to rolling improve the efficiency.

Further, while accommodating a plurality of stages of absorber heat transfer tubes, a plurality of protrusions are formed between the upper stage absorber heat transfer pipes and the lower stage absorber heat transfer pipes to form a twist angle of 15 ° or less on the outer surface of the pipe. A ridge is formed, and the valley between the ridge and the ridge is formed into a curved surface, and an absorber provided with a heat transfer tube for an absorber in which the radius of curvature of the valley is larger than the radius of curvature of the ridge is provided. Therefore, even if the absorbing liquid dripping from the heat transfer tube becomes non-uniform, the absorbing liquid is guided to the peaks and troughs by the heat transfer tube having a lower twist angle than the heat transfer tube Flow to the part where there is little
The outer surface of the lower heat transfer tube can be uniformly wetted, heat transfer performance is improved, and the absorption capacity of refrigerant vapor in an absorber equipped with a particularly large size heat transfer tube can be improved. The operating efficiency of the machine can be improved.

Furthermore, the ridges and valleys of the plurality of ridges formed on the outer surface of the pipe are curved, the radius of curvature of the valley is made larger than the radius of curvature of the ridge, and the outer surface of the pipe is made smooth. Since the heat exchanger tubes are provided with the heat exchanger tubes having the tube plate support portions formed at both ends and the tube support support portion having the outer surface of the tube smoothed at the intermediate portion, the heat transfer tubes are supported by the tube sheet and the support. The plate can be easily supported by using the tube plate support part and the tube support support part, and the tube plate and the tube plate support part of the heat transfer tube can be reliably sealed by expanding the tube plate support part. Therefore, the airtightness of the absorption refrigerator can be improved.

Further, since the height of the ridges is gradually lowered toward the tube plate support portion and the tube support support portion, it is possible to avoid the occurrence of cracks or the like at the ends of the mountain portion or the valley portion, and the absorption refrigerator. It is possible to simplify the operation of maintenance and inspection.

[Brief description of drawings]

FIG. 1 is a schematic circuit configuration diagram of an absorption refrigerator.

FIG. 2 is a cross-sectional view of an evaporation absorber body.

FIG. 3 is a front view of a heat transfer tube.

FIG. 4 is a cross-sectional view taken along the line AA of the heat transfer tube shown in FIG.

FIG. 5 is a cross-sectional view of a heat transfer tube in which a film of an absorbing liquid is formed on the outer surface of the tube.

FIG. 6 is a schematic configuration diagram of an absorber.

FIG. 7 is a partial front view of a heat transfer tube.

FIG. 8 is a diagram showing the relationship between the absorption liquid flow rate and the heat exchange amount.

FIG. 9 is a schematic configuration diagram of an absorber.

FIG. 10 is a cross-sectional view of an evaporation absorber body.

[Explanation of symbols]

1 Evaporative absorber body 2 evaporator 3 absorber 4 High temperature regenerator 11 Low temperature regenerator 12 condenser 30 spraying devices 31 heat transfer tube 32 ridges 33 Yamabe 34 Tanibe 36 heat transfer tube 37 Ridge 38 Yamabe 40 Tanibe

Claims (5)

[Claims] 1. An absorption refrigerating machine in which a refrigeration cycle is formed by connecting an absorber, a regenerator, a condenser and an evaporator by piping, and a plurality of ridges are formed in the longitudinal direction on the outer surface of the pipe. The ridge and the valley between adjacent ridges are curved, and the radius of curvature of the valley is larger than the radius of curvature of the ridge, and the absorbing liquid from the regenerator is dropped or sprayed on the outer surface of the tube. An absorption chiller comprising an absorber having a heat transfer tube for an absorber that cools an absorption liquid outside the pipe with cooling water inside the pipe. 2. A regenerator, an absorber and a condenser containing a heat transfer tube for an absorber in which the absorbing liquid from the regenerator is dropped or sprayed on the outer surface of the pipe and the absorbing liquid outside the pipe is cooled by cooling water inside the pipe. In an absorption refrigerator in which a refrigeration cycle is formed by connecting an evaporator to a pipe, a plurality of ridges having a twist angle of 15 ° or less are formed on the outer surface of the pipe so that they have a continuous curved surface shape, and Radius of curvature R ₁ and radius of valley R ₂
An absorption refrigerator having an absorber having a heat transfer tube for absorber in which the ratio R ₂ / R ₁ is larger than 1. 3. A regenerator, an absorber having a heat transfer tube for an absorber that cools the absorption liquid outside the pipe by cooling or dripping the absorption liquid from the regenerator on the outer surface of the pipe, a condenser, and In an absorption refrigerator that forms a refrigeration cycle by connecting an evaporator to a pipe, having a plurality of stages of heat transfer tubes for the absorber, and an absorber heat transfer tube provided in the upper stage and an absorber heat transfer tube provided in the lower stage In between, a plurality of ridges having a twist angle of 15 ° or less are formed on the outer surface of the pipe, and the peaks of the ridges and the valleys between adjacent ridges are curved surfaces, and An absorption type refrigerator comprising an absorber provided with a heat transfer tube for an absorber having a radius of curvature larger than that of a mountain portion. 4. A regenerator, an absorber having a heat transfer tube for an absorber, in which the absorbing liquid from the regenerator is dripped or sprayed on the outer surface of the pipe, and the absorbing liquid outside the pipe is cooled by cooling water in the pipe, a condenser. In an absorption refrigerator in which a refrigeration cycle is formed by connecting an evaporator to a pipe, a pair of tube plates facing each other, a tube support provided between these tube plates, and a plurality of protrusions formed on the outer surface of the tube. In addition, the peaks and valleys of the ridges are curved, the radius of curvature of the valleys is made larger than that of the peaks, and smoothed tube plate support portions are formed on both ends of the tube outer surface. An absorption refrigerator having an absorber provided with a heat transfer tube for an absorber in which a tube support supporting portion having a smooth surface is formed in an intermediate portion. 5. The absorption refrigerator according to claim 4, wherein the height of the projection is gradually reduced toward the tube sheet support portion and the tube support support portion.