CN112082418A - Evaporation tube for shell-and-tube heat exchanger and manufacturing method thereof - Google Patents

Abstract

The technical scheme of the present invention is an evaporation tube for a shell-and-tube heat exchanger, which comprises a tube body, the main fins are spirally wound on the outer surface of the tube body; channels are formed between the adjacent main fins, The top of the main fin is formed with a groove and at least one groove sub-fin, the two sides of the groove are the first part and the second part of the groove sub-fin, and the first part of the groove sub-fin is formed. larger than the second part of the groove sub-fins, the channel, the main fin and the first part of the groove sub-fins and the second part of the groove sub-fins on the adjacent main fins form a first boiling cavity, The groove and the first portion of the groove sub-fins form a second boiling cavity. The invention can form a plurality of boiling cavities, which is beneficial to increase the heat exchange area and increase the boiling effect.

Description

Evaporation tube for shell-and-tube heat exchanger and manufacturing method thereof

technical field

The invention relates to an evaporating tube for a shell-and-tube heat exchanger, in particular to an evaporating tube suitable for use in a shell-and-tube heat exchanger and a manufacturing method thereof.

Background technique

For the heat exchange tube manufacturing industry, to improve the energy efficiency of refrigeration and air conditioning equipment, it is mainly achieved by developing high-efficiency heat transfer tubes to improve the heat exchange efficiency of heat exchangers. Especially in the evaporating tube used in refrigeration and air conditioning systems, the boiling heat transfer thermal resistance of the refrigerant when the refrigerant is boiling outside the tube is quite large compared to the forced convection heat transfer thermal resistance in the tube, even greater than the thermal resistance of forced convection heat transfer inside the tube. Therefore, Strengthening the boiling heat transfer outside the tube can have a significant effect on improving the heat transfer performance of the evaporating tube.

The research on the mechanism of nucleate boiling shows that the heat transfer capacity of the evaporation tube can be improved by forming fins on the outer surface of the heat transfer tube. In the prior art, the heat exchange capacity can be improved by improving the inner surface of the evaporating tube in contact with the cooling medium. An example of improving the inner surface of a heat exchange tube can be found in US Pat. No. 3,847,212 which discloses a method of forming ridges on the inner surface of a heat exchange tube.

In the prior art, the heat exchange capacity is also improved by improving the fins. For example, US Patent 4,660,630 discloses the formation of nucleate boiling cavities or voids by notching or notching fins on the outer surface of the tube. This configuration allows the bubbles to pass outward through the cavity, to or through a narrower surface opening, further enhancing heat transfer. Another example is the heat exchange tubes for evaporators disclosed in Chinese Patents 95246323.7 and 03207498.0, the outer surface of which is pressed into a T-shaped helical fin at the top to form a groove structure or a cavity structure with a slightly smaller opening, so as to construct a place for forming a vaporization core. , so as to achieve the effect of enhancing the boiling heat transfer.

In the prior art, the heat exchange capacity is also improved by further improving the outer surface fins. For example, Chinese Patent No. 200910002853.8 discloses a double-bubble core structure formed by inclining the outer fins of the tube to cause a part of the dividing channels of the sub-fins of the outer tube fins to form a double-bubble core structure. This structure enhances heat transfer between the cooling medium flowing through the heat transfer tubes and the refrigerant into which the heat transfer tubes are immersed through the unique location of the second boiling cavity.

The above-mentioned existing technologies all have good effects on improving evaporative boiling heat transfer, but in the boiling heat transfer mechanism, the boiling process requires the supplement of refrigerant liquid and the discharge of generated gas, which is the key to boiling heat transfer. Insufficient refrigerant liquid replenishment will cause the phenomenon of “drying up” in the boiling process, which will lead to the deterioration of boiling, and the inconvenience of refrigerant gas discharge will cause the internal pressure of the cavity to be too high, which will lead to a higher vaporization saturation temperature and reduce the heat transfer effect.

SUMMARY OF THE INVENTION

The purpose of the present invention is to design an evaporating tube for a shell-and-tube heat exchanger with a reasonable structure and good use effect and a manufacturing method thereof.

The technical solution of the present invention is an evaporating tube for a shell-and-tube heat exchanger, which includes a tube body, and is characterized in that: the main fins are spirally wound on the outer surface of the tube body; A channel is formed between the main fins, a groove and at least one groove sub-fin are formed on the top of the main fin, the two sides of the groove are the first part and the second part of the groove sub-fins, and the groove sub-fins are formed. The first part of the fin is larger than the second part of the groove sub-fin, the first part of the channel, the main fin and the groove sub-fin and the second part of the groove sub-fin on the adjacent main fin form the first part. A boiling cavity, the groove and the first portion of the groove sub-fins form a second boiling cavity. The first part of the grooved fins in this solution is more conducive to introducing the refrigerant liquid into the first boiling cavity, and the second part of the grooved fins is more conducive to leading the refrigerant gas out of the first boiling cavity.

The included angle between the main fin and the axial direction is 5-30°.

There are 26-60 main fins per inch along the axial direction of the tube body, and the helix angle is 0.3-2.5°.

There are 60 to 160 grooves distributed along the circumferential direction.

The inner surface of the pipe body is provided with internal teeth, the internal teeth are threaded, the axial section of the internal teeth is trapezoidal, and the tip angle of the internal teeth ranges from 10° to 120°.

The included angle between the inner teeth and the axis of the pipe body ranges from 20 to 70°, the number of the inner teeth is 6 to 90, and the height of the inner teeth is 0.1 to 0.6 mm.

A method for manufacturing an evaporating tube for a shell-and-tube heat exchanger, comprising the following steps:

Step 1: First form the main spiral fins on the tube body, and at the same time form the channels between the main fins;

Step 2, then use a knurling knife to form grooves and sub-fins on the top of the main fins, and the grooves form the first part and the second part of the groove fins due to the extension;

Step 3: Bend the main fins by about 5~30° with an oblique tool, while shortening the second part of the groove fins, the channel, the main fins and at least the first part of the groove fins form the first boiling cavity;

Step 4: A closed cavity is formed by pressing the bisected fins with a rolling tool, and the grooves and the divided fins and at least the first part and or the second part of the groove fins form a second boiling cavity.

In the second step, the main fins can also be bent by 5~30° through an inclined cutter.

In the third step, grooves and sub-fins are formed on the top of the main fin by knurling. The first part of the fin is larger than the second part, thereby forming a first boiling cavity formed by the channel, the first part of the main fin and the groove sub-fin and the second part of the groove sub-fin on the adjacent main fin The groove and the first part of the groove sub-fins form a second boiling cavity.

The beneficial effects of the present invention are:

1. Multiple boiling cavities can be formed, which is beneficial to increase the heat exchange area and increase the boiling effect.

2. The upper part of the second boiling chamber is in contact with the refrigerant liquid, which is beneficial to guide the refrigerant liquid from the second boiling chamber into the first boiling chamber and prevent the supercooled liquid from directly submerging the vaporization core. At the same time, the existence of the second boiling chamber can guide part of the refrigerant gas from the first boiling chamber into the second boiling chamber, which is conducive to the discharge of the refrigerant gas and prevents the phenomenon that the cavity pressure is too high and the heat transfer effect is reduced.

3. The first part of the formed groove sub-fins guides the refrigerant liquid from the second boiling chamber into the first boiling chamber, preventing the supercooled liquid from directly submerging the vaporization core; the second part of the formed groove sub-fins will guide part of the refrigerant The gas enters the second boiling chamber from the first boiling chamber, which is conducive to the discharge of refrigerant gas and prevents the phenomenon that the cavity pressure is too high and the heat transfer effect is reduced.

4. The second boiling chamber is independent of the first boiling chamber, and can also play the role of increasing the vaporization core.

Description of drawings

Fig. 1 is the structural representation of the present invention,

Figure 2 is a partial cross-sectional view of the present invention,

FIG. 3 is a flow chart of the implementation process of the processing method of the present invention.

Detailed ways

The technical solutions of the present application are described in detail with reference to the accompanying drawings:

Example 1

An evaporating tube for a shell and tube heat exchanger includes an integrally formed tube body 1 and main fins 2, the main fins 2 are spirally wound on the outer surface of the tube body; the adjacent main fins 1 are formed between Channel 4, the top of the main fin is knurled to form a groove 5 and at least one sub-fin 6, the two sides of the groove are the first part 51 and the second part 52 of the groove sub-fin, the concave The first part 51 of the slot fin is larger than the second part 52, the channel 4, the main fin 2 and the first part 51 of the slot sub-fin and the second part 52 of the slot sub-fin on the adjacent main fin are formed The first boiling cavity 7; the groove 5 and the first part 51 of the groove fins form the second boiling cavity 8, and the first part 51 of the groove fins is more conducive to the introduction of refrigerant liquid into the second boiling cavity 8. A boiling cavity 7 , and the second part 52 of the grooves and fins is more conducive to lead the refrigerant gas out of the first boiling cavity 7 .

The included angle between the main fin and the axial direction is 5°;

There are 26 main fins per inch along the axial direction of the tube body, and the helix angle is 0.3°;

60 of the grooves are distributed along the circumferential direction;

The inner surface of the pipe body is provided with internal teeth 3, the internal teeth are threaded, the axial section of the internal teeth is trapezoidal, and the range of the tip angle of the internal teeth is 10°;

The range of the included angle between the inner teeth and the axis of the pipe body is 20°, the number of inner racks is 6, and the height of the inner teeth is 0.1 mm.

Example 2,

A kind of evaporating tube for shell-and-tube heat exchanger as described in embodiment 1, its specific structural parameters are as follows:

The included angle between the main fins and the axial direction is 30°.

There are 60 main fins per inch along the axial direction of the tube body, and the helix angle is 2.5°.

The grooves are distributed 160 in the circumferential direction.

The inner surface of the pipe body is provided with internal teeth, the internal teeth are threaded, the axial cross section of the internal teeth is trapezoidal, and the tip angle range of the internal teeth is 120°.

The included angle between the inner teeth and the axis of the pipe body is 70°, the number of inner racks is 90, and the height of the inner teeth is 0.6 mm.

Example 3,

A kind of evaporating tube for shell-and-tube heat exchanger as described in embodiment 1, its specific structural parameters are as follows:

The included angle between the main fin and the axial direction is 25°.

There are 46 main fins per inch along the axial direction of the tube body, and the helix angle is 1.8°.

90 of the grooves are distributed along the circumferential direction.

The inner surface of the pipe body is provided with internal teeth, the internal teeth are threaded, the axial section of the internal teeth is trapezoidal, and the tip angle of the internal teeth ranges from 110°.

The included angle between the inner teeth and the axis of the pipe body is 60°, the number of inner racks is 56, and the height of the inner teeth is 0.4 mm.

Example 4,

The processing method for processing an evaporation tube for a shell-and-tube heat exchanger described in Example 1 is as follows: as shown in Figures 1 and 2, the outer diameter of the heat exchange tube is 19 mm, the wall thickness is 1.13 mm, and a rolled tube is used. The machine is combined with extrusion processing, and the inside and outside of the tube are integrated at the same time. As shown in Figure 2, in the first step, the copper tube rolling tool 9a forms the main fins 2 and channels 4 on the outside of the tube; in the second step, a special disc knurling tool 9b is used to roll down from the top of the main fins 2 to form fins The groove 5 and the two sub-fins 6, the groove 5 forms the first part 51 and the second part 52 of the groove fin due to the extension; the third step is to bend the main fin by about 5~30° through the inclined cutter 9c At the same time, the second part 52 of the groove sub-fin is formed, and then the first part of the channel, the main fin and the groove sub-fin and the second part of the groove sub-fin on the adjacent main fin are formed. The first boiling cavity 7; the fourth step, the bisected fin is pressed by the rolling tool 9d to form a closed cavity, and the groove 5 and the first part 51 of the groove divided fin form the second boiling cavity 8 .

As shown in Figure 1 and Figure 3. The second boiling cavity 8 is located obliquely above the first boiling cavity 7, the channel 4, the main fin 2 and the first part 51 of the groove sub-fin and the first part 51 of the groove sub-fin on the adjacent main fin The two parts 52 form the first boiling cavity 7 ; the groove 5 and the first part 51 of the groove fins form the second boiling cavity 8 .

The above-mentioned embodiments are merely examples for clear illustration, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. It is not necessary and impossible to list all the embodiments here, and the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims (9)

1. An evaporation tube for a shell-and-tube heat exchanger, comprising a tube body, characterized in that: the main fins are spirally wound on the outer surface of the tube body; a channel is formed between the adjacent main fins, so that the The top of the main fin is formed with a groove and at least one groove sub-fin, the two sides of the groove are the first part and the second part of the groove sub-fin, and the first part of the groove sub-fin is larger than The second part of the groove sub-fin, the channel, the main fin and the first part of the groove sub-fin and the second part of the groove sub-fin on the adjacent main fin form the first boiling cavity, so The groove and the first portion of the groove sub-fins form a second boiling cavity. 2 . The evaporating tube for a shell-and-tube heat exchanger according to claim 1 , wherein the included angle between the main fin and the axial direction is 5-30°. 3 . 3 . The evaporating tube for a shell-and-tube heat exchanger according to claim 1 , wherein the main fins are provided with 26-60 fins per inch along the axial direction of the tube body, and the helix angle is 0.3-2.5°. 4 . . 4 . The evaporating tube for a shell and tube heat exchanger according to claim 1 , wherein 60 to 160 grooves are distributed along the circumferential direction. 5 . 5 . The evaporating tube for a shell and tube heat exchanger according to claim 1 , wherein the inner surface of the tube body is provided with internal teeth, the internal teeth are threaded, and the shaft of the internal teeth is threaded. 6 . The cross section is trapezoidal, and the tip angle of the inner teeth ranges from 10° to 120°. 6 . The evaporating tube for a shell and tube heat exchanger according to claim 1 , wherein the angle between the inner teeth and the axis of the tube body ranges from 20° to 70°, and the number of the inner gear racks ranges from 6 to 90°. 7 . The height of the inner teeth is 0.1 to 0.6 mm. 7. A method for manufacturing an evaporating tube for a shell-and-tube heat exchanger, comprising the following steps: Step 1: First form the main spiral fins on the tube body, and at the same time form the channels between the main fins; Step 2, then use a knurling knife to form grooves and sub-fins on the top of the main fins, and the grooves form the first part and the second part of the groove fins due to the extension; Step 3: Bend the main fins by 5~30° with an oblique tool, and at the same time shorten the second part of the groove fins, the channel, the main fins and at least the first part of the groove fins form the first boiling cavity; Step 4: A closed cavity is formed by pressing the bisected fins with a rolling tool, and the grooves and the divided fins and at least the first part and or the second part of the groove fins form a second boiling cavity. 8 . The method for manufacturing an evaporating tube for a shell-and-tube heat exchanger according to claim 7 , wherein in the second step, the main fins can also be bent by 5-30° with an inclined cutter. 9 . 9 . The method for manufacturing an evaporating tube for a shell and tube heat exchanger according to claim 7 , wherein in the third step, grooves and sub-fins are formed on the top of the main fin by a knurling knife. 10 . , the grooves form the first part and the second part of the groove fins due to the extension, and the first part of the groove fins formed at the same time is larger than the second part, thereby forming the channel, the main fin and the groove. The first part of the sub-fin and the second part of the groove sub-fin on the adjacent main fin form a first boiling cavity, and the groove and the first part of the groove sub-fin form a second boiling cavity body.

Images