JP2000035295A - Heat transfer tube with inner surface grooves - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer tube with inner surface grooves for reducing a pressure loss by winding up heating medium liquid on an overall inner surface of the tube in the case of using the tube as an evaporating tube or gathering the medium to a bottom in the tube in the case of using the tube as a condensing tube. SOLUTION: A finless region 2 extending in an axial direction and a fin forming region 4 are formed on an inner periphery of a metal tube, and fins 6 obliquely extending substantially symmetrically from a center of a circumferential direction of the region 4 toward both right and left sides are formed on the region 4. A width of the region 2 in a circumferential direction of the tube is 5 to 40% of an inner circumferential length of the tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a metal pipe having an inner surface
The present invention relates to a heat transfer tube having an inner surface groove formed with fins for improving heat exchange efficiency.

[0002]

2. Description of the Related Art This type of heat transfer tube with an inner groove is mainly used as an evaporator tube or a condenser tube in a heat exchanger of an air conditioner or a cooling device. Heat transfer tubes having a shape of a fin are widely commercially available.

[0003] A heat transfer tube, which is currently the mainstream, is formed by passing a floating plug having a spiral groove on the outer peripheral surface thereof through a seamless (seamless) tube obtained by drawing or extruding. Is manufactured by a method of rolling fins over the entire inner peripheral surface.

[0004] In the heat transfer tube with an inner groove formed with such a spiral fin, if the steam flow flowing through the tube is sufficiently fast,
The heat transfer medium liquid accumulated on the lower side inside the heat transfer tube is wound up along the spiral fin while being swept away by the vapor flow, and spreads over the entire inner peripheral surface of the tube. By this action, the entire inner circumferential surface of the pipe is almost uniformly wetted, so that it is possible to prevent so-called dryout in which a part of the inner circumferential surface of the pipe is dried, and it is possible to increase the area of a region where boiling occurs and increase the boiling efficiency. it can.

On the other hand, when a heat transfer tube with an inner groove formed with a spiral fin is used as a condensation tube for liquefying a heat transfer gas, the fin tip protrudes from a liquid film which wets the inner surface of the tube. Thus, the effect of increasing the contact efficiency between the metal surface and the heat medium gas and increasing the condensation efficiency can be obtained.

[0006]

According to the study by the present inventors, the heat transfer tube with the inner surface groove having the spiral fins has the following problems, so that there is room for further improving the heat exchange efficiency. Turned out to be.

When used as an evaporation tube, if the flow rate of the heat medium flowing in the tube is relatively small, a liquid film cannot be formed on the entire inner surface of the tube, and dryout is likely to occur.
That is, in the heat transfer tube with the inner surface groove having the spiral fins, in order to wet the entire inner surface of the tube with the heat medium liquid, the heat medium liquid to be accumulated at the bottom of the tube is applied to the entire inner surface of the tube against the gravity. However, in order to give the heat medium liquid a momentum enough to make a helical rotation, the heat medium gas must flow at a considerably large flow rate. Just drop it and it will fall immediately.

[0008] In both cases of use as an evaporating tube or a condensing tube, the main flow of the heat medium liquid flowing through the bottom of the tube and the helical fins violently collide with each other, whereby the flow of the heat medium liquid is interrupted and a pressure loss occurs. However, since the fins in this part are submerged in the liquid, they do not contribute much to the improvement of the evaporation or condensation action. This problem becomes even more pronounced when the inclination angle of the fin with respect to the tube axis is increased for the purpose of improving the evaporation or condensation efficiency.

When used as a condensing tube, the heat medium liquid is gathered at the bottom of the tube as opposed to the evaporation tube, so that the fins on the inner peripheral surface of the tube are not covered with an excessive liquid film. Desirably, in the inner grooved heat transfer tube having a spiral fin,
If the flow rate of the heat medium is increased, the heat medium liquid is inevitably wound up, so that the inner peripheral surface of the tube gets wet, and the condensation effect of the fins cannot be fully utilized.

The present invention has been made in view of the above circumstances, and when used as an evaporating tube, the heat transfer medium liquid can be effectively scraped over the entire inner surface of the tube, while when used as a condensing tube, It is an object of the present invention to provide a heat transfer tube with an inner surface groove which can collect a heat medium liquid at the bottom of the tube and can reduce a pressure loss.

[0011]

In order to solve the above-mentioned problems, a first heat transfer tube with an inner surface groove according to the present invention comprises a finless region extending in an axial direction of the metal tube on an inner peripheral surface of the metal tube. A fin forming region is formed, and a large number of fins are formed in the fin forming region and extend substantially symmetrically inclining toward the left and right sides from the center in the circumferential direction.

In a second heat transfer tube with an inner surface groove according to the present invention, a fin low-density region and a fin high-density region extending in the axial direction of the metal tube are formed on the inner peripheral surface of the metal tube. In the fin high-density region, short fins inclined with respect to the axial direction of the metal tube are formed substantially symmetrically with respect to the center of the circumferential direction of the fin high-density region. A feature is that long fins inclined with respect to the axial direction of the metal tube are formed over both of the fin high-density regions.

In the third heat transfer tube with an inner groove according to the present invention, the center angle around the axis of the metal tube is 1 on the inner peripheral surface of the metal tube.
Two regions forming an angle of 80 ° are formed.
A large number of fins extending obliquely from a first boundary portion to a second boundary portion of these regions are formed substantially symmetrically with respect to the first boundary portion, and an inclination formed between the fins and the axis of the metal tube. The absolute value of the angle increases in at least a part of the section from the first boundary to the second boundary.

Further, in the fourth heat transfer tube with an inner surface groove according to the present invention, two regions having a central angle of 180 ° around the axis of the metal tube are formed on the inner peripheral surface of the metal tube. Is formed with a large number of fins extending obliquely from a first boundary portion to a second boundary portion of these regions, and the width of a groove formed between adjacent fins is set to be smaller than the first boundary portion. 2
Characterized in that it decreases while approaching the boundary of.

[0015]

[First Embodiment] FIG. 1 is a partially developed plan view showing a first embodiment of a heat transfer tube with an inner surface groove according to the present invention. This heat transfer tube 1 with an inner groove is generally made of copper,
It is made of a metal such as copper alloy, aluminum, and aluminum alloy, and has a finless region 2 and a fin-forming region 4 with a constant width formed on the inner peripheral surface thereof. ing. A large number of fins 6 are formed in the fin forming region 4 so as to extend substantially symmetrically from the center 3 in the circumferential direction (corresponding to the broken line in FIG. 1) to both left and right sides. Here, the term “substantially symmetric” means that it is not necessary to be geometrically perfect line symmetry. For example, the fins 6 on both sides of the center portion 3 may be slightly shifted in the axial direction. Or
This means that the inclination angles of the fins 6 on both sides may be slightly different, and the lengths and shapes of the left and right fins 6 may be slightly different. In short, the left and right fins 6 only need to be inclined in opposite directions.

The diameter and thickness of the inner grooved heat transfer tube 1 are not limited, but may be any size and thickness of a general heat transfer tube, for example, an outer diameter of 6 to 10 mm and a thickness of 0.2 to 0. .3
mm. Of course, products outside this range can also be manufactured. The manufacturing method of the heat transfer tube 1 with the inner surface groove is not limited.
In this case, a welded portion 10 extending in the tube axis direction is formed on a part of the heat transfer tube 1 with the inner surface groove in the circumferential direction. The position of the welded portion 10 is not limited and may be at the center of the fin forming region 4, may be at the center of the finless region 2 as shown by a two-dot chain line in the drawing, or may be at other positions. It doesn't matter. However, in consideration of the easiness of the electric resistance sewing, it is preferable to be located at the position of the finless area 2.

In this embodiment, the cross-sectional shape of the inner grooved heat transfer tube 1 is circular. However, the present invention is not limited to a circular cross-section, and may be an elliptical cross-section or a flat tube if necessary. Further, it is also possible to fill a working fluid such as pure water, alcohol, chlorofluorocarbon, or a mixed solvent under reduced pressure in the inside grooved heat transfer tube 1 and close both ends of the tube to use as a heat pipe.

The finless region 2 is a portion where the fin 6 is not formed, and is desirably a smooth surface. When using the inner grooved heat transfer tube 1 of this embodiment,
It is preferable that the axis of the heat transfer tube 1 with the inner surface groove is substantially horizontal, and the finless region 2 is disposed facing downward. When used in such an attitude, the main flow portion of the heat medium liquid flows along the finless region 2, so that the fins 6 are less likely to hinder the flow of the heat medium liquid, and the pressure loss of the heat medium is correspondingly reduced. Can be reduced.

The width W1 of the finless region 2 in the circumferential direction of the tube is not limited, but is preferably 5 to 40% of the entire circumferential length of the inner circumferential surface of the tube. Within this range, the pressure loss of the heat medium liquid is small, and the effect of scraping up the heat medium liquid by the fins 6 described later is also good. More preferably, the width W1 is 10% to 20% of the entire circumference of the inner peripheral surface of the tube, and optimally 10% to 1%.
5%.

The fin forming region 4 indicates a region other than the finless region 2 on the inner peripheral surface of the heat transfer tube 1 having the inner surface groove.
A large number of fins 6 parallel to each other are formed so as to form a so-called arrow wing shape symmetrical with respect to the center 3 of the circumferential width. The fins 6 located on both sides of the center 3
They may be connected in a V-shape, or may be separated at the center 3. When divided at the central portion 3, the welded portion 10 may be formed at the central portion 3, and in that case, the welded portion 10 and the fin 6 may or may not be connected. .

When the welded portion 10 is formed in the center portion 3 of the fin forming region 4, as shown in the figure, a grooveless portion 7 having a fixed width is formed on both sides of the center portion 3 before the electric sewing. It may be formed parallel to the edge. These non-grooved portions 7 are desirable in order to make the welding current density generated on the end face of the strip material uniform when the strip material is subjected to ERW to form a tubular shape.

Although the absolute value of the inclination angle α of the fin 6 with respect to the tube axis is not limited, it is generally preferably 5 to 30 °, more preferably 10 to 25 °, and most preferably 15 to 20 °. is there. If the absolute value exceeds 30 °, the fins 6 become nearly perpendicular to the flow, which has a large effect of blocking the flow and increases the pressure loss, which is not preferable. If the absolute value is less than 5 °, the fins 6 become nearly parallel to the flow, and the effect of scraping the heat transfer medium upward by the fins 6 and the effect of improving the heat transfer efficiency are reduced. In particular, the outer diameter of the inner grooved heat transfer tube 1 is 7 mm or less, and the flow rate of the heat medium flowing through the inner grooved heat transfer tube 1 is 20 kg /.
When the angle is equal to or less than the hour, if the absolute value of the inclination angle α of the fin 6 with respect to the tube axis is 5 to 12 °, the scraping effect becomes good. This is common to the embodiments described later.

The cross-sectional shape of the fin 6 is triangular, isosceles triangular, triangular with a rounded apex, semi-circular,
Any shape such as an arc, a rectangle, a trapezoid, or a chamfered trapezoid may be used. Finless area 2 of fin 6
The side fin tip 6A is pointed in this embodiment. Thereby, care is taken to prevent excessive turbulence from being generated by the fin tip 6A.

Although the bottom width FW and the height of the fin 6 are not limited in the present invention, the height of the fin 6 is preferably 0.1 mm.
1 to 0.3 mm, more preferably 0.15 to 0.2
5 mm. In this embodiment, the finless area 2
Since the pressure loss is reduced due to the formation of the fins 6, the height of the fins 6 can be increased accordingly. If the fins 6 are too low, the effect of scraping the heat transfer medium liquid will be small, and if the fins 6 are too high, the pressure loss will increase. The bottom width FW of the fin 6 is preferably 0.1 to 0.3 mm, more preferably 0.15 to
0.25 mm. The ratio H / FW between the height H of the fin 6 and the bottom width FW is preferably about 0.33 to 3. Within this range, the balance between the effect of agitating the heat transfer liquid and the pressure loss is improved.

When both side surfaces of the fin 6 are substantially flat, the angle (vertical angle) formed by these two side surfaces can be defined. The apex angle is not limited, but is preferably 10 to 4
0 °, more preferably 20 ° to 30 °.
Within such a range, not only the balance between the effect of agitating the heat transfer liquid and the pressure loss is improved, but also the tip of each fin 6 tends to be exposed when used as a condensation tube. , The contact area between the heat medium gas and the metal surface is increased, and high condensation efficiency can be obtained.

The groove 8 is a portion through which a part of the heat medium liquid scraped up by the fins 6 passes, and has an appropriate amount for transporting the heat medium liquid along the groove 8 while securing an appropriate flow rate. It preferably has a width. The width GW of the groove 8 is not limited.
It is preferably about 0.4 mm, and more preferably about 0.4 mm.
It is about 2 to 0.3 mm.

The welded portion 10 is preferably a ridge having a projection smaller than the projection of the fin 6 so as not to hinder the expansion of the heat transfer tube 1 through the expansion plug. The cross-sectional shape of the welded portion 10 is not limited, but generally has a shape such as a semi-elliptical shape. If necessary, the projecting welded portion 10 generated by the electric resistance sewing may be removed by machining.

An example of a method of manufacturing the above-described heat transfer tube 1 with an inner groove will be described. First, the fins 6 and the grooves 8 are formed by rolling rolls while running a metal plate strip, and then the roll forming apparatus is used. The plate material is gradually rolled into a pipe shape, and the both side edges of the plate material are abutted after induction heating. As a result, the side edges are welded to form a metal tube, and the welded portion is formed as necessary to obtain the inner grooved heat transfer tube 1.

The inner grooved heat transfer tube 1 is used by being incorporated in a heat exchanger such as an air conditioner or a cooler. At this time, the inner grooved heat transfer tube 1 should be arranged substantially horizontally and incorporated so that the finless region 2 is located at the lower end. When used as an evaporation tube, the heat medium flows in the direction of arrow A in the figure, and when used as a condensation tube, the heat medium flows in the direction of arrow B in the figure.

When used as an evaporating tube, the main flow of the heat transfer liquid flowing in the direction A in the figure flows along the finless region 2, so that it hardly collides with the fins 6 and has a large kinetic energy. Since the flow is not hindered, it is possible to reduce the pressure loss of the entire heat medium flowing in the heat transfer tube 1 with the inner surface groove. When a part of the heat medium liquid flowing in the direction A in the figure comes into contact with the fins 6, the heat medium liquid (L) is scooped obliquely upward by the fins 6 (F) as shown in FIG. It flows along the groove 8 to the upper end of the inner surface of the pipe. At this time, the surface tension of the groove 8 also helps transport of the heat transfer liquid. At the upper end of the inner surface of the pipe, the flows of the heat medium liquid flowing along the left and right fins 6 collide with each other, and the heat medium liquid drops while scattering.

As described above, in the heat transfer tube with inner grooves 1,
Since the fins 6 extending obliquely upward are formed on the left and right wall surfaces of the inner surface of the tube, if the heat transfer medium travels along the fins 6 near the upper end of the inner surface of the tube, a sufficient effect of wetting the entire inner surface of the tube can be obtained. . Therefore, even when the flow rate of the heat medium is relatively small, the effect of preventing dry-out on the inner surface of the pipe is high. Furthermore, since the pressure loss of the heat medium is low due to the formation of the finless region 2, the load on the heat medium pump can be reduced, and the heat exchange efficiency of the entire heat exchange device can be increased.

On the other hand, even when the heat transfer tube 1 with the inner surface groove is used as a condenser tube, the main flow of the heat transfer liquid flowing in the direction B in the drawing flows along the finless region 2 and therefore collides with the fin 6. And the flow of the heat medium liquid having a large kinetic energy is hardly obstructed. Therefore, it is possible to reduce the pressure loss of the entire heat medium flowing in the heat transfer tube 1 with the inner surface groove. When the heat medium flowing in the direction B in the drawing contacts the fins 6 and liquefies, the generated heat medium liquid is quickly pushed obliquely downward along the fins 6 and the grooves 8 by the force of the heat medium gas. Then, as shown in FIG. 11, it flows through the finless region 2 while merging with the main flow of the heat medium liquid L.

As described above, in the heat transfer tube 1 with the inner groove,
Since the fins 6 extending obliquely downward in the traveling direction are formed on the left and right wall surfaces of the tube, the heat medium liquid can be quickly discharged to eliminate the liquid film covering the fins 6, and the metal surface of the fins 6 and the heat medium It is possible to enhance the condensation efficiency by promoting direct contact with the gas. Further, even when the heat exchanger is used as a condenser, the pressure loss of the heat medium is low due to the formation of the finless region 2, so that the load on the heat medium pump is reduced, and the heat exchange efficiency of the entire heat exchanger is increased. It is possible.

In the case of an air conditioner for both cooling and heating, a heat medium flows in the same heat transfer tube in opposite directions during cooling and during heating. Good effects can be obtained in both cooling and heating.

[Second Embodiment] FIG. 2 shows a second embodiment of the present invention. In this heat transfer tube 1 having an inner groove, the fin 6 has an arc shape with the inner surface of the tube developed in a plane. It is characterized by being curved as follows. As a result, the absolute value of the inclination angle α of the fin 6 with respect to the tube axis gradually increases from the fin tip 6A toward the other end (upper end) of the fin 6. The difference between the maximum value and the minimum value of the fin angle α in the same fin 6 is preferably about 10 to 20 °. Other configurations may be the same as in the first embodiment.

According to such an embodiment, when the fin 6 is used as an evaporating tube, the lower end of the fin 6 has a small angle with respect to the axis, so that the heat medium liquid flowing in the direction A in FIG. The impact is small, and the resistance of the fin 6 to the flow of the heat medium liquid can be reduced as compared with the first embodiment. On the other hand, the fin 6
Is nearly vertical, so that the heat medium liquid rising along the groove 8 can be quickly delivered to the ceiling surface of the pipe.

When the fin 6 is used as a condenser tube, the angle of the fin 6 with respect to the axis at the lower end of the fin 6 is small. In spite of the small size, the fin 6 is close to vertical at the upper end of the fin 6, so that the contact between the heat medium gas and the fin 6 can be made more intense, and there is an advantage that the condensation efficiency can be promoted.

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention. In this heat transfer tube 1 having an inner groove, the shape of the fins 6 is changed to an S-shape with the inner surface of the tube developed in a plane. It is characterized by being curved. Accordingly, the absolute value of the inclination angle α of the fin 6 with respect to the pipe axis gradually increases from the fin tip 6A toward the center of the fin 6, and thereafter,
Further, it decreases toward the upper end of the fin 6. Other configurations may be the same as in the first embodiment.

According to such an embodiment, when the fin 6 is used as an evaporating tube, since the angle with respect to the axis at the lower end of the fin 6 is small, the heat medium liquid flowing in the direction A in FIG. The impact is small, and the resistance of the fin 6 to the flow of the heat medium liquid can be reduced as compared with the first embodiment. On the other hand, the fin 6
Is close to vertical, the heat medium liquid rising along the groove 8 can be quickly delivered to the ceiling surface of the pipe,
Further, since the fin angle is small on the ceiling surface of the fin 6, the collision between the heat medium liquids running up on the ceiling surface can be reduced, and the pressure loss due to the collision can be reduced.

When the fin 6 is used as a condenser tube, the angle of the fin 6 with respect to the axis at the lower end of the fin 6 is small. Despite the small size, the fins 6 are close to vertical at the center of the fins 6, so that the contact between the heat medium gas and the fins 6 is more intense. There is an advantage that when the heat medium liquid is easily pushed by the heat medium gas, the heat medium liquid easily flows down along the fins 6.

[Fourth Embodiment] FIG. 4 shows a fourth embodiment of the present invention. In this heat transfer tube 1 having an inner surface groove, a low density fin extending in the axial direction of the metal tube is provided on the inner peripheral surface of the metal tube. The region 12 and the fin high-density region 14 are respectively formed. In the fin high-density region 14, short fins 6 inclined with respect to the axial direction of the metal tube are provided.
Are formed substantially symmetrically with respect to the center in the circumferential direction. Further, the fin low-density region 12 and the fin high-density region 14
A long fin 16 that is inclined with respect to the axial direction of the metal tube is formed over both of them.

That is, in this embodiment, the long fins 16 are formed by extending a part of the fins 6 of the first embodiment to the center of the finless area 2. And two short fins 6 are arranged at equal intervals. Width W1 of fin low density region 12 and width W2 of fin high density region 14
May be the same as the widths W1 and W2 in the first embodiment. The angles and dimensions of the fins 6, 16 and the groove 8 are also the first.
It may be the same as the embodiment.

According to such an embodiment, when used as an evaporation tube, the main flow of the heat medium liquid flowing in the direction A in the figure flows along the fin low-density region 12, so that the frequency of collision with the fin 16 is low. Since the flow of the heat medium liquid having a large kinetic energy is hardly obstructed, the pressure loss of the entire heat medium flowing in the heat transfer tube 1 with the inner surface groove can be reduced.
Further, a part of the heat medium liquid flowing in the direction A in the drawing
When the heat medium liquid comes into contact with 16, the heat medium liquid is scooped diagonally upward, and flows along the groove 8 to the upper end of the inner surface of the tube due to inertial force. At this time, since the lower end of the long fin 16 is in the main flow of the heat transfer liquid, the lifting force of the heat transfer liquid by the long fin 16 is larger than the lifting force of the short fin 6. Therefore, this embodiment has a stronger scraping effect than the first embodiment even when the flow rate of the heat medium is the same.
Further, dryout can be effectively prevented even in a region where the flow rate of the heat medium is small.

When used as a condenser tube, the main flow of the heat transfer liquid flowing in the direction B in the drawing flows along the fin low-density region 12, so that it hardly collides with the fins and has a large kinetic energy. It does not hinder the flow of the heat transfer liquid. Therefore, it is possible to reduce the pressure loss of the entire heat medium flowing in the heat transfer tube 1 with the inner surface groove. Further, since the heat transfer liquid flowing in the direction B in the drawing is always converged to the center of the fin low-density region 12 every time it comes into contact with the fins 16, it is possible to effectively prevent the flow of the heat transfer liquid from spreading. Has advantages.

[Fifth Embodiment] FIG. 5 shows a fifth embodiment of the present invention. In the fourth embodiment, two long fins 16 and two short fins 6 are arranged. In this embodiment, the long fins 16 and the short fins 6 are alternately arranged. Features. If the density of the long fins 16 is increased, the pressure loss increases,
Since the effect of raising the heat medium liquid or the effect of converging the heat medium liquid is improved, the density of the long fins 16 should be appropriately set in accordance with the use conditions of the heat transfer tube 1 with the inner surface groove. The same adjustment can be performed by relatively changing the heights of the long fin 16 and the short fin 6.

[Sixth Embodiment] FIG. 6 shows a sixth embodiment of the present invention. In this embodiment, two regions R1 and R2 having a central angle of 180 ° around the axis of the metal tube are formed on the inner peripheral surface of the metal tube, and these regions R1 and R2 are formed of these regions R1 and R2. From the first boundary 25 to the second
A large number of fins 26 and grooves 28 extending obliquely to the boundary 3 are formed substantially symmetrically with the first boundary 25 as a boundary. Since these fins 26 are curved in an S-shape in the unfolded state, the absolute value of the inclination angle α formed between the fins 26 and the axis of the metal pipe is determined from the first boundary 25 to the center of each of the regions R1 and R2. Steadily increased, and then
It decreases again while going from each central part to the second boundary part 3. The difference between the maximum value and the minimum value of the fin angle α in the same fin 26 is preferably about 10 to 20 °. Other configurations may be the same as in the first embodiment.

According to such an embodiment, when the fin 26 is used as an evaporating tube, the heat medium liquid flowing in the direction A in the figure collides with the fin 26 because the angle α with respect to the axis at the lower end of the fin 26 is small. And the resistance of the fins 26 to the flow of the heat transfer liquid can be reduced as compared with the heat transfer tubes with spiral fins. On the other hand, the fins 26
In the center of the fin 26 is close to vertical,
The heat medium liquid rising along the groove 28 can be quickly sent to the ceiling surface of the pipe, and the fin angle is small on the ceiling surface of the pipe inner surface. Can be alleviated and the pressure loss due to the collision can be reduced.

When the fin 26 is used as a condensing tube, since the angle of the fin 26 with respect to the axis is small at the lower end of the fin 26, the heat medium liquid flowing in the direction B in FIG.
Fin 2
6, the fin 26 is almost vertical at the center, so that the contact between the heat medium gas and the fin 26 is more intense. Further, the fin angle is small at the ceiling, so that the heat medium liquid that tends to stagnate on the ceiling surface is formed. This has the advantage that it easily flows down along the fins 26 when pushed by the heat medium gas.

[Seventh Embodiment] FIG. 7 shows a seventh embodiment of the present invention. This embodiment is characterized in that fins 26 curved in an arc shape are formed in an expanded state.
The absolute value of the inclination angle α formed between the fin 26 and the axis of the metal tube gradually increases from the first boundary 25 to the second boundary 3. Other configurations may be similar to those of the first and sixth embodiments.

According to such an embodiment, when the fin 26 is used as an evaporating tube, the heat medium liquid flowing in the direction A in FIG. And the resistance of the fins 26 to the flow of the heat transfer liquid can be reduced as compared to the heat transfer tubes with helical fins. The effect of quickly sending the heat medium liquid rising along 28 to the ceiling surface of the pipe is high.

When the fin 26 is used as a condensing tube, since the angle of the fin 26 with respect to the axis is small at the lower end of the fin 26, the heat medium liquid flowing in the direction B in FIG.
Fin 2
Since the fins 26 are almost perpendicular from the center to the upper end of 6, the contact between the heat medium gas and the fins 26 becomes more intense, and there is an advantage that the condensation efficiency is high.

[Eighth Embodiment] FIG. 8 shows an eighth embodiment of the present invention. In this embodiment, the fins 26 bent in a “C” shape in the unfolded state are connected to the first boundary portion 25.
Is formed in each of the regions R1 and R2 so as to be symmetrical with respect to. Thereby, the absolute value of the inclination angle α formed between the fin 26 and the axis of the metal pipe increases discontinuously on the way from the first boundary 25 to the second boundary 3. Other configurations may be the same as in the first embodiment. The width W1 of the region where the fin angle α is small may be the same as the width W1 of the finless region 2 in the first embodiment. Other configurations may be the same as in the first embodiment. According to such an embodiment, effects similar to those of the seventh embodiment can be obtained.

[Ninth Embodiment] FIG. 9 shows a ninth embodiment of the present invention. In this embodiment, two center angles of 180 ° around the axis of the metal tube are formed on the inner peripheral surface of the metal tube. Region R
In the regions R1 and R2, a large number of fins 36 extending from the first boundary portion 25 to the second boundary portion 3 of these regions R1 and R2 are formed. A feature of this embodiment is that the width of the groove 38 formed between the adjacent fins 36 decreases while going from the first boundary 25 to the second boundary 3. That is,
The groove 38 becomes narrower toward the ceiling surface of the inner peripheral surface of the tube, so that the capillary force of the groove 38 increases.

At the same time, the height of the fins 36 increases from the first boundary 25 to the second boundary 3. That is, the fins 36 are gradually raised toward the ceiling surface of the inner peripheral surface of the tube, and the bottom width is also increased.

The opening width of the groove 38 is not limited, but is preferably 0.1 to 0.4 mm on the first boundary 25 side and 0.01 to 0.20 mm on the second boundary 3 side. Within this range, the effect of transporting the heating medium liquid by the capillary force is improved. The opening width of the groove 38 is more preferably 0.15 to 0.30 mm on the first boundary 25 side, and the second boundary 3
It is 0.05 to 0.15 mm on the side of the first boundary 25 and optimally 0.05 to 0.10 mm on the side of the second boundary 3.

The height of the fins 36 is not limited.
Is preferably 0.01 to 0.1 mm on the side of the boundary 25 and 0.1 to 0.3 mm on the side of the second boundary 3. Within this range, the effect of transporting the heating medium liquid by the capillary force is improved. The height of the fins 36 is more preferably 0.03 to 0.10 mm on the first boundary portion 25 side and 0.15 to 0.25 mm on the second boundary portion 3 side. 1
Is 0.05 to 0.08 mm on the side of the boundary 25 and 0.20 to 0.25 mm on the side of the second boundary 3.

The bottom width of the fins 36 is not limited.
Is preferably 0.01 to 0.1 mm on the side of the boundary 25 and 0.1 to 0.3 mm on the side of the second boundary 3. Within this range, the heat medium disturbing effect of the fins 36 is improved. The bottom width of the fins 36 is more preferably 0.01 to 0.08 mm on the first boundary portion 25 side and 0.15 to 0.25 mm on the second boundary portion 3 side. 0.04 to 0.08 mm on the side of the first boundary 25, the second boundary 3
0.15 to 0.20 mm on the side.

According to such an embodiment, when the fin 36 is used as an evaporating tube, the fin 36 is low at the lower end of the fin 36, so that the impact when the fin 36 collides with the heat medium liquid flowing in the direction A in the drawing. And the resistance of the fins to the flow of the heat transfer liquid can be reduced as compared with the heat transfer tubes with spiral fins. On the other hand, since the height of the fins 26 increases toward the ceiling, the fins 36 have a strong force to lift up the heat transfer medium liquid on both sides of the flow of the heat transfer liquid, and the heat once lifted up. The medium liquid is reliably delivered to the ceiling surface by the fins 36 which increase in height. In addition, since the width of the groove 38 is reduced toward the ceiling surface, the capillary force of the groove 38 is increased on the ceiling surface side. From this point, the heating medium liquid is supplied to the ceiling surface reliably and uniformly. Thus, dryout can be prevented.

Although the embodiments of the present invention have been described individually, the present invention is not limited to only the above embodiments, and the components of the above embodiments may be combined with each other. For example, the configuration in which the groove width in FIG. 9 is reduced as it goes upward may be combined with the embodiment in FIGS.

[0060]

As described above, according to the heat transfer tube with inner grooves according to the present invention, when used as an evaporation tube, the heat transfer medium liquid is lifted up to the ceiling surface by the fins on both side walls extending obliquely upward. Therefore, even when the flow rate of the heat medium is small, it is possible to effectively wet the entire inner surface of the pipe, and the effect of preventing dryout is high. In addition, since the collision impact between the fin and the heat medium liquid at the bottom in the tube can be reduced, the flow of the heat medium liquid is less obstructed, and the pressure loss of the heat medium can be reduced.

When the heat medium liquid attached to the fins due to the condensation is pushed by the flow of the heat medium when used as a condensation tube, the heat medium liquid quickly falls to the bottom of the tube along the fins on both side walls extending obliquely downward. Therefore, the drainage property on the inner surface of the pipe is improved, the fins are prevented from being covered with the liquid film, and the direct contact between the fins and the heat medium gas is promoted, so that the condensation efficiency can be increased. Further, also in this case, since the collision impact between the fin and the heat medium liquid at the bottom of the pipe can be reduced, the flow of the heat medium liquid is less obstructed, and the pressure loss of the heat medium can be reduced. It is.

[Brief description of the drawings]

FIG. 1 is a partially developed plan view of an inner surface of a heat transfer tube with an inner surface groove according to a first embodiment of the present invention.

FIG. 2 is a partially developed plan view of an inner surface showing a second embodiment of the present invention.

FIG. 3 is a partially developed plan view of an inner surface showing a third embodiment of the present invention.

FIG. 4 is a partially developed plan view of an inner surface showing a fourth embodiment of the present invention.

FIG. 5 is a partially developed plan view of an inner surface showing a fifth embodiment of the present invention.

FIG. 6 is a partially developed plan view of an inner surface showing a sixth embodiment of the present invention.

FIG. 7 is a partially developed plan view of an inner surface showing a seventh embodiment of the present invention.

FIG. 8 is a plan view in which an inner surface according to an eighth embodiment of the present invention is partially developed.

FIG. 9 is a plan view in which an inner surface according to a ninth embodiment of the present invention is partially developed.

FIG. 10 is a sectional view of an evaporating tube showing the effect of the present invention.

FIG. 11 is a sectional view of a condenser tube showing the effect of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 heat transfer tube with internal groove 2 finless area 4 fin forming area 6, 26, 36 fin 6A fin tip (lower end) 8, 28, 38 groove 10 welded part α fin angle 12 fin low density area 14 fin high density area 16 long Fin R1, R2 region 25 first boundary 3 second boundary

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiichi Ishikawa 128-7 Ogimachi, Aizuwakamatsu-shi, Fukushima Pref. Wakamatsu Works (72) Inventor Shin Kikuchi 128-7, Ogimachi 128-1, Aizuwakamatsu-shi, Fukushima Mitsubishi Shindoh Inside Wakamatsu Manufacturing Co., Ltd. (72) Inventor ▲ Sukumo ▼ Shun Ta ▲ Green ▼ 128-7 Ogimachi, Aizuwakamatsu-shi, Fukushima Mitsubishi Shindoh Inside Wakamatsu Manufacturing Co., Ltd.

Claims (8)

[Claims] A finless region (2) and a fin forming region (4) extending in the axial direction of the metal tube are formed on an inner peripheral surface of the metal tube, respectively, and the fin forming region (4) is provided.
A fin (6) extending from the center in the circumferential direction of the fin forming region (4) to the left and right sides so as to be substantially symmetrically inclined.
A heat transfer tube with an inner surface groove, wherein a heat transfer tube is formed. 2. The heat transfer tube with an inner groove according to claim 1, wherein the width of the finless region in the circumferential direction of the metal tube is 5 to 40% of the inner circumferential length of the metal tube. 3. The heat transfer tube with an inner groove according to claim 1, wherein an inclination angle of the fin with respect to an axial direction of the metal tube is 5 to 30 °. 4. The absolute value of the inclination angle of the fin (6) with respect to the axis of the metal tube is small at the end of the fin (6) on the fin-free area (2) side, and becomes relatively smaller toward the other end. The heat transfer tube with an inner surface groove according to any one of claims 1 to 3, wherein the heat transfer tube has an inner groove. 5. A low density fin region (12) and a high density fin region (14) extending in the axial direction of the metal tube are formed on the inner peripheral surface of the metal tube, respectively. The short fin (6) inclined with respect to the axial direction of the metal tube is formed substantially symmetrically with respect to the center of the fin high-density region (14) in the circumferential direction, and the fin low-density region ( A heat transfer tube having an inner groove, wherein a long fin (16) inclined with respect to the axial direction of the metal tube is formed over both the fin (12) and the fin high-density region (14). 6. The heat transfer tube with an inner groove according to claim 5, wherein the width of the fin low-density region in the circumferential direction of the metal tube is 5 to 40% of the inner circumferential length of the metal tube. . 7. Two regions (R1, R2) having a central angle of 180 ° around the axis of the metal tube are formed on the inner peripheral surface of the metal tube, and these regions have a first boundary between these regions. A large number of fins (26) extending obliquely from the portion (25) to the second boundary portion (3) are formed substantially symmetrically with the first boundary portion (25) as a boundary. An inner grooved transmission characterized in that the absolute value of the inclination angle (α) formed by the axis of the metal pipe increases in at least a part of the section from the first boundary to the second boundary. Heat tube. 8. Two regions (R1, R2) having a central angle of 180 ° around the axis of the metal tube are formed on the inner peripheral surface of the metal tube, and these regions have a first boundary between these regions. A number of fins (26) extending obliquely from the portion (25) to the second boundary (3) are formed, and the adjacent fins (2) are formed.
The width of the groove (28) formed during the step (6) decreases in the direction from the first boundary (25) to the second boundary (3). .