JP2000039231A - Heat transfer pipe and absorption refrigerating machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat-exchanging property between absorption liquid dropped in the outside of a pipe and cooling water passing through the inside of the pipe in an absorber. SOLUTION: A heat transfer pipe 1 provided horizontally inside an absorber comprises a cylindrical pipe part 2 through which cooling water passes and plural fins 3 provided in rows in an axial direction of an outer circumferential surface of the cylindrical pipe part 2, wherein the fins 3 are formed into states where a part of each of the fins 3 is eliminated in a circumferential direction of the cylindrical pipe part 2, and the eliminated parts, the parts 4 of the circumferential direction of the cylindrical pipe parts 2 where the fins 3 are not formed (hereinafter the parts 4 are referred to as circumferential parts 4 without fins), are provided in rows so as to be arranged linearly. The heat transfer pipe 1 may be provided with plural fins 3 in the circumferential direction of the cylindrical pipe part 2 in rows apart from each other so that the circumferential parts 4 without fins of the cylindrical pipe part 2 are dispersed into plural places. The fins 3 are limited to be 1.5 mm or thinner in thickness and 2-5 mm in height, wherein the fins 3 are provided in rows in the outer surface and the axial direction of the cylindrical pipe part 2 and have distances of 5-15 mm each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigerator and a heat transfer tube incorporated in the absorber.

[0002]

2. Description of the Related Art In an absorber of an absorption refrigerator, an absorbing liquid is dropped and the refrigerant evaporated by the evaporator is absorbed into the dropped absorbing liquid. The absorption reaction of the refrigerant by the absorbing liquid is an exothermic reaction, and the lower the temperature of the absorbing liquid, the easier the refrigerant vapor is to be absorbed by the absorbing liquid. It is configured to drop the absorbing liquid onto the heat tube.

[0003] In the heat transfer tube 1X of the absorber exhibiting the above function, for example, as shown in Fig. 17, a disk-shaped fin 3X is provided on the outer surface of the circular tube portion 2 in the axial direction of the circular tube portion 2. The heat transfer area is increased so that good heat exchange can be performed between the cooling water passing through the inside of the circular tube portion 2 and the absorbing liquid dripping outside the tube.

[0004]

However, in the heat transfer tube 1X having the above-described structure, if the absorbing liquid is dropped on the uppermost heat transfer tube 1X of the plurality of heat transfer tubes 1X arranged horizontally in the absorber, the absorption is reduced. The liquid mainly gathers at the lower end of the fins 3X of the heat transfer tubes 1X and flows down from there onto the heat transfer tubes 1X further downward, but the positions of the fins 3X of the heat transfer tubes 1X positioned above and below are matched. However, it is rare that the absorbent flowing down from above is evenly distributed to both sides of the fins 3X of the lower heat transfer tube 1X.
For example, the position of X is slightly shifted left and right as shown in FIG. 18, for example. In such an arrangement, the position of X drops from the n-th fin 3Xn counted from, for example, the left side of the upper heat transfer tube 1X. The absorbed liquid dropped onto the right circular tube portion 2 of the n-th fin 3Xn counted from the left side of the lower heat transfer tube 1X.

The fins 3Xn of the lower heat transfer tube 1X
Absorbing liquid dropped on the circular pipe part 2 on the right side of
Because of the presence of n, the tubular portion 2 cannot be expanded to the left, but only to the right. However, since the distance to the fin 3Xn + 1 on the right side of the fin 3Xn is long, it does not expand there, so In the heat transfer tube 1X, since the left side surface of each fin 3X and the circular tube portion 2 in the vicinity thereof are not wetted by the absorbing liquid, the absorbing liquid dropped on the surface and the cooling water passing through the inside of the circular tube portion 2 However, there is a problem that the heat exchange characteristics of the above are not improved as expected, and this is a problem to be solved.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is directed to a heat transfer tube having a plurality of fins arranged in an axial direction outside the tube.
The heat transfer tube of the first configuration, in which the fins are formed in a portion except for a part in the circumferential direction of the tube, and the fins having a thickness of 1.5 mm or less and a height of 2 to 5 mm are arranged at intervals of 5 to 15 mm in the axial direction. A heat transfer tube of the second configuration, which is arranged in a row, and 2 to 10 fins are arranged in a line in the circumferential direction of the tube, and a portion where no fin is formed is dispersed in 2 to 10 places in the circumferential direction of the tube. A heat transfer tube having a third configuration arranged so as to be disposed, a heat transfer tube having a fourth configuration having a hole penetrating through the fin, and a heat transfer tube having a fifth configuration having a recess formed in the fin A heat transfer tube having a sixth configuration in which the fins are formed in a corrugated plate shape; a heat transfer tube having a seventh configuration in which the fins are formed to be wider toward the tip end; Any of the heat transfer tubes described above, with the peripheral portion where no fins are formed facing upward, There is provided a built-in absorption chillers.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to FIGS.
6 will be described. FIG. 1 is a schematic diagram showing the configuration of an absorption refrigerator, in which an aqueous solution of a base such as lithium bromide is used as an absorbing liquid and water is used as a refrigerant. In the figure, 51 is a heater composed of a burner or the like, 52 is a high-temperature regenerator provided with the heater 51, 53 is a low-temperature regenerator, 54 is a condenser arranged in parallel with the low-temperature regenerator 53, 55 is an absorber, 56 Is an evaporator arranged in parallel with the absorber 55. The high-temperature regenerator 52 and the absorber 55 are connected via an absorption liquid pipe 61 provided with an absorption liquid pump 57 in the middle, and the high-temperature regenerator 52 and the condenser 54 is connected via a refrigerant pipe 62, and the high-temperature regenerator 52 and the low-temperature regenerator 53 are connected via an absorbing liquid pipe 63, and a high-temperature heat exchanger 59 is provided in the middle of the absorbing liquid pipe 63. ing.

Further, the low-temperature regenerator 53 and the absorber 55 are connected via an absorbing solution pipe 64 so that the absorbing solution can be sprayed on a number of heat transfer tubes 1 installed horizontally inside the absorber 55. It has become. A cooling water pipe 65 is also connected to the heat transfer pipe 1 and also extends inside the condenser 54 so that cooling water can be supplied to each of the cooling water pipes 65. Also,
A low-temperature heat exchanger 58 is provided in the absorption liquid pipe 64.

The condenser 54 and the evaporator 56 are connected via a refrigerant pipe 66. The refrigerant pipe 66 is provided with a refrigerant pump 60, and the refrigerant liquid collected at the bottom of the evaporator 56 is discharged from the evaporator 56. It is configured so that it can be sprayed on a large number of heat transfer tubes 1A installed horizontally in the inside. And heat transfer tube 1
A is connected to a cold water pipe 67.

In the absorption refrigerator having the above-described structure, the mixture of the absorption liquid and the refrigerant is heated by the heater 51 in the high-temperature regenerator 52 to separate the high-temperature refrigerant vapor. The refrigerant is sent to the low-temperature regenerator 53 through 62, where the absorption liquid in the low-temperature regenerator 53 is heated to lower the temperature of the refrigerant, and then enters the condenser 54 and radiates heat to the cooling water supplied from the cooling water pipe 65. And liquefy.

The refrigerant liquefied in the condenser 54 is sent to the evaporator 56 via the refrigerant pipe 66, and is sprayed on a number of heat transfer tubes 1A installed horizontally, such as water flowing inside the heat transfer tubes 1A. The evaporated refrigerant takes away heat from the brine, and the evaporated refrigerant enters the absorber 55, where it is absorbed by the concentrated absorbent returned from the low-temperature regenerator 53 via the absorbent pipe 64 to become a dilute solution, and again becomes a high-temperature regenerator. The refrigerant is sent to the pump 52 through the absorbent pipe 61 by the absorbent pump 57, and the circulation of the refrigerant as described above is maintained.

Then, while flowing inside the heat transfer tube 1A, brine, such as water, which has been deprived of heat as the latent heat of evaporation of the refrigerant and whose temperature has been lowered, is supplied to the load through the chilled water pipe 67 to be cooled. Provided.

The absorption liquid in the low-temperature regenerator 53, which is heated by the high-temperature refrigerant vapor sent from the high-temperature regenerator 52 and evaporates and separates the refrigerant vapor, is heated in the high-temperature regenerator 52 to evaporate and separate the refrigerant. The intermediate absorbent having a reduced concentration is exchanged with the dilute liquid sent from the absorber 55 to the high-temperature regenerator 52 by the high-temperature heat exchanger 59 to be sent at a reduced temperature.

The heat transfer tube 1 which is installed in the absorber 55 and through which the cooling water is passed is, for example, shown in FIGS.
To the shape shown in FIG. That is, the heat transfer tube 1 is composed of a circular tube portion 2 through which cooling water passes, and a plurality of fins 3 arranged in an axial direction on an outer peripheral surface of the circular tube portion 2. It is formed on the part excluding the part.

For example, in the heat transfer tube 1 shown in FIGS. 2 and 3, a plurality of fins 3 are arranged at equal intervals in the axial direction of the outer surface of the circular tube portion 2. And each fin 3 is a circular tube part 2
Is formed in a partially interrupted state in the circumferential direction, and the interrupted portion, that is, the circumferential portion 4 of the circular tube portion 2 where the fins 3 are not formed (hereinafter, this portion is referred to as a finless circumferential portion) ) Are arranged in a line so as to form a linear arrangement.

When the fins 3 are thick, the heat transfer tubes 1
Not only becomes heavy but also deteriorates the heat exchange characteristic between the cooling water passed through the circular tube portion 2 and the absorbing liquid dropped outside the tube. It is formed.

The height of the fins 3 is preferably in the range of 2 to 5 mm. That is, the fin 3 is 2
If it is less than 5 mm, the effect of improving the heat exchange characteristics is small, and if it is more than 5 mm, a dry portion appears.
When the entire heat transfer tube 1 is installed, the fins 3 interfere with each other and occupy a large space, that is, when the plurality of heat transfer tubes 1 are installed, that is, the installation density is reduced, and the overall heat exchange characteristics are rather reduced. Because of the drawbacks, the fin 3 is usually limited to a height of 2 mm or more and 5 mm or less.

It is preferable that the fins 3 are arranged in a row in the axial direction of the outer surface of the circular tube portion 2 at an interval of 5 to 15 mm. In other words, the heat exchange characteristics are improved as the number of the fins 3 is increased in principle. The flow of the refrigerant vapor to be absorbed by the adsorbing liquid to the surface of the pipe portion 2 is prevented, and the fin 3 is
If the fins 3 are arranged at intervals larger than m, the effect of improving the heat exchange characteristics of the fins 3 is reduced. Therefore, the fins 3 are usually arranged at an interval of 5 mm or more and 15 mm or less in the axial direction of the circular tube portion 2. Are arranged in a row.

Further, the fins 3 are formed wider on the tip side than on the side in contact with the circular tube portion 2 so that the heat transfer area is kept large.

In the heat transfer tube 1 having the above structure,
When the circular tube portion 2 is installed on the absorber 55 with the finless circumferential portion 4 facing upward, the position of the fins 3 of the heat transfer tube 1 installed vertically is shifted left and right as shown in FIG. Even if it does, the absorbing liquid dropped on the outer surface of the tube spreads in both the left and right directions through the finless circumferential portion 4 of the circular tube portion 2 and wets the entire surface of the circular tube portion 2 and the left and right surfaces of the fins 3. In addition, the heat exchange characteristic between the cooling water passed through the circular pipe portion 2 and the absorbing liquid dropped outside the pipe is improved.

The heat transfer tube 1 is, as shown in FIGS.
The finless circumferential portion 4 of the circular tube portion 2 may be formed so as to be distributed and located at a plurality of locations.

For example, in the heat transfer tube 1 shown in FIGS. 4 and 5, four fins 3 are arranged at equal intervals in the circumferential direction of the circular tube portion 2 and the finless circular portion of the circular tube portion 2 is formed. 4 are distributed in four places.

A plurality of fins 3 are linearly arranged in the axial direction of the circular tube portion 2 from the respective positions of the four fins 3 distributed in the circumferential direction of the circular tube portion 2.

In the heat transfer tube 1 shown in FIGS. 6 and 7, eight fins 3 are arranged at equal intervals in the circumferential direction of the circular tube portion 2, and the finless circular portion of the circular tube portion 2 is formed. 4 are distributed in eight places.

Also in this case, a plurality of fins 3 are linearly arranged in the axial direction of the circular tube portion 2 from the respective positions of the eight fins 3 which are dispersedly arranged in the circumferential direction of the circular tube portion 2. ing.

In the heat transfer tube 1 shown in FIGS. 8 and 9, one of the four fins 3 arranged in the circumferential direction of the circular tube portion 2 shown in FIGS. It is omitted.

As described above, in the heat transfer tube 1 in which the finless circumferential portions 4 of the circular tube portion 2 are provided at a plurality of locations, the heat transfer tube 1 in which the finless circumferential portions 4 are provided in only one location is used. In comparison, there is an advantage that the absorbing liquid dropped on the outer surface of the tube is more likely to spread in the lateral direction of the circular tube portion 2.

When the heat transfer tube 1 is incorporated into the absorber 55, the finless circumferential portion 4 of the tube portion 2 is disposed above the tube so that the absorbing liquid dropped on the outer surface of the tube tends to spread in the lateral direction. There is also an advantage that the probability of being performed is increased.

The number of the fins 3 arranged in the circumferential direction on the outer surface of the circular tube portion 2 is preferably 10 or less. When the fins 3 are arranged in a row in the circumferential direction of the outer surface of the circular tube portion 2 exceeding 10 fins, the fins 3 are formed to have a thickness of 1.5 mm or less, so that the fins 3 have insufficient strength. 3 has a disadvantage that the fins 3 are easily damaged, so the number of the fins 3 arranged in the circumferential direction on the outer surface of the circular tube portion 2 is limited to 10 or less.

FIG. 10 shows a heat transfer tube 1 having the structure shown in FIGS. 4 and 5, and a plurality of ridges formed longitudinally on the outer surface of the tube described in Japanese Patent Application Laid-Open No. 9-152289. Performance comparison diagram with conventional heat transfer tube with curved peaks and valleys between strips (liquid film flow rate 0.03 k in conventional heat transfer tube)
g / m · s, the heat transfer performance was 100%). As is apparent from this drawing, the heat transfer performance of the heat transfer tube 1 according to the present invention is the same as that of the conventional heat transfer tube at any flow rate. The heat transfer performance is more than 20% better.

Further, as shown in FIGS. 11 and 12, the heat transfer tube 1 can be formed with a through hole 5 in the fin 3.

In the heat transfer tube 1 configured as described above,
The flow of the absorbent flowing down the surface of the fins 3 is disturbed by the presence of the holes 5 and the residence time in the fins 3 is prolonged. There is an advantage that the heat exchange characteristic with the cooling water to be used is further improved.

The refrigerant vapor to be absorbed by the absorbing liquid is
Therefore, the refrigerant vapor that has evaporated in the evaporator 56 and entered the absorber 55 can easily enter the opposite side of the evaporator 56, and the refrigerant vapor is absorbed by the absorbing liquid even at a position far away from the evaporator 56. There is also an advantage that it is absorbed quickly.

In the heat transfer tube 1, the fins 3 may be formed in a corrugated shape as shown in FIGS.
Also in the heat transfer tube 1 formed in this manner, the speed of the absorbing solution flowing down the surface of the fin 3 becomes slow, so that the heat of the absorbing solution dropped on the outer surface of the tube and the cooling water passed through the circular tube portion 2 are generated. There is an advantage that the exchange characteristics are improved. The corrugated fins 3 may be formed in concentric corrugated plates.

Then, the heat transfer tube 1 having the above-mentioned shape is
Of the heat transfer tube 1 installed on the upper and lower sides even if the positions of the fins 3 of the heat transfer tube 1 installed on the upper and lower sides are shifted right and left. The dripped absorbing liquid spreads in both left and right directions through the finless circumferential portion 4 of the circular tube portion 2 and wets the entire surface of the circular tube portion 2 and the left and right surfaces of the fins 3. The heat exchange characteristics between the cooling water passed through and the absorbing liquid dropped to the outside of the tube are improved.

By the way, as shown in FIGS. 15 and 16, for example, as shown in FIGS. 15 and 16, a plurality of short tubes 6 provided with fins 3 at one end in a flange shape by punching or the like are used.
The fins 3 are formed in such a manner that the fins 3 are aligned and inserted into the circular pipe 7, and then the circular pipe 7 is expanded in diameter and the short pipe 6 is fixed to the circular pipe 7.

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the present invention.

[0038]

As described above, in the absorber of the absorption refrigerator incorporating the heat transfer tube of the present invention, the heat exchange between the absorbing liquid dropped outside the tube and the cooling water passed through the tube is performed. Since the characteristics of the absorber are improved, it is possible to reduce the size of the absorber and to have a remarkable effect in saving the energy of the absorption refrigerator.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an absorption refrigerator.

FIG. 2 is a perspective view showing one embodiment of a heat transfer tube.

FIG. 3 is a side view of the heat transfer tube shown in FIG.

FIG. 4 is a perspective view showing another embodiment of the heat transfer tube.

FIG. 5 is a side view of the heat transfer tube shown in FIG.

FIG. 6 is a perspective view showing another embodiment of the heat transfer tube.

FIG. 7 is a side view of the heat transfer tube shown in FIG.

FIG. 8 is a perspective view showing another embodiment of the heat transfer tube.

FIG. 9 is a side view of the heat transfer tube shown in FIG.

FIG. 10 is a diagram showing performance comparison results.

FIG. 11 is a perspective view showing another embodiment of the heat transfer tube.

FIG. 12 is a side view of the heat transfer tube shown in FIG.

FIG. 13 is a perspective view showing another embodiment of the heat transfer tube.

FIG. 14 is a side view of the heat transfer tube shown in FIG.

FIG. 15 is a perspective view showing one procedure for making a heat transfer tube.

FIG. 16 is a cross-sectional view showing one procedure for making a heat transfer tube.

FIG. 17 is an explanatory diagram showing a configuration of a conventional heat transfer tube.

FIG. 18 is an explanatory diagram showing an arrangement of a conventional heat transfer tube in an absorber.

[Explanation of symbols]

 1.1X heat transfer tube 2 Circular tube portion 3 / 3X fin 4 Circular portion without fins 5 Hole 6 Short tube 7 Circular tube 51 Heater 52 High temperature regenerator 53 Low temperature regenerator 54 Condenser 55 Absorber 56 Evaporator 57 Absorbing liquid Pump 58 Low temperature heat exchanger 59 High temperature heat exchanger 60 Refrigerant pump

Claims (8)

[Claims] 1. A heat transfer tube in which a plurality of fins are arranged in an axial direction outside the tube, wherein the fins are formed in a portion excluding a part in a circumferential direction of the tube. 2. The heat transfer tube according to claim 1, wherein fins having a thickness of 1.5 mm or less and a height of 2 to 5 mm are arranged in an axial direction at intervals of 5 to 15 mm. 3. Two to ten fins are arranged in a line in the circumferential direction of the tube, and a portion where no fin is formed is two in the circumferential direction of the tube.
The heat transfer tube according to claim 1 or 2, wherein the heat transfer tube is dispersedly arranged at 10 to 10 locations. 4. The heat transfer tube according to claim 1, wherein a hole penetrating the fin is provided. 5. The heat transfer tube according to claim 1, wherein the fin is provided with a recess. 6. The heat transfer tube according to claim 1, wherein the fin is formed in a corrugated shape. 7. The heat transfer tube according to claim 1, wherein the fin is formed so as to have a larger width toward the tip. 8. The heat transfer tube according to claim 1, wherein the heat transfer tube according to any one of claims 1 to 7 is incorporated with a peripheral portion having no fin formed thereon as a heat transfer tube of an absorber through which cooling water is passed. An absorption refrigerator.