JPH0650236B2 - Heat transfer tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a contact convection type apparatus which is disposed laterally in a heating tank and flows a heat source fluid therein to heat a fluid to be heated in the heating tank. The present invention relates to the improvement of the heat transfer tube.

(Prior Art) Conventionally, a heat transfer tube having a uniform circular cross section is laterally arranged in a heating tank, and a heat source fluid is circulated inside to heat a fluid to be heated in the heating tank. As means for increasing the efficiency of heat transfer from the heat transfer tube, many fins are provided on the outer circumference of the heat transfer tube, or twists are formed in the heat transfer tube to swirl the heat source fluid to generate a turbulent air flow. there were.

(Problems to be Solved by the Invention) However, in such a conventional contact convection type heat transfer tube, when the heat transfer surface is increased with fins, the heat transfer resistance of the material causes the amount of heat transfer to increase toward the tip. In a horizontally placed heat transfer tube in which a large number of fins are provided in parallel with the axis, the separated gas in the fluid to be heated stays between the fins and the fins in a portion below the axis,
This stagnant gas, which has a much lower thermal conductivity than that of the fluid, causes a local heat transfer failure, which causes distortion in the heat transfer tube and drastically reduces the amount of heat exchange.

In addition, if a turbulent flow is generated in the heat source fluid and it is attempted to effectively spread it over the entire length of the heat transfer tube, the frictional resistance of the fluid in the tube will increase significantly, resulting in a significantly larger energy loss than in the case of parallel flow. There was a problem that occurs.

In view of the above conventional problems, the present invention is a contact convection type in which the amount of heat exchange is much larger than that of the conventional one, and distortion does not occur due to local heat transfer failure, and the fluid friction resistance does not increase. The purpose is to provide a heat transfer tube.

(Means for Solving the Problems) The gist of the present invention for achieving the above-mentioned object is that the heating source fluid is disposed laterally in a heating tank and allows a heat source fluid to flow inside thereof. In a heat transfer tube that heats, the outer heat transfer plate having a cutout formed by cutting out the lower part of the tubular body along the longitudinal direction, and the cutout is closed and connected, and protrudes upward into the outer heat transfer plate. In addition, an inner heat transfer plate that forms a downward recess that continues along the longitudinal direction of the outer heat transfer plate, and a fluid to be heated is circulated above the outer heat transfer plate in a substantially central portion of the recess. A vertical flow passage is provided.

(Operation) The contact convection type heat transfer tube according to the present invention is disposed laterally in the heating tank, flows the heat source fluid therein, and heats the fluid to be heated in the heating tank. The plate protrudes inside the outer heat transfer plate and forms a downward recess that is continuous in the lateral direction to obtain a large heat transfer surface in the same volume and turbulence is less likely to occur. Is positively discharged and circulated above the outer heat transfer plate through a vertically oriented flow path provided in the substantially central portion, and the fluid to be heated is circulated to stir the whole.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, a plurality of contact convection type heat transfer tubes 10 according to the present invention are integrally incorporated into a liquid heater F as shown in FIGS. 14 to 16 and horizontally immersed in the liquid. The heat transfer tube unit D is configured.

First, the structure of the fluid heater F horizontally placed in the heating tank with the heat transfer tube unit D as a heating means will be described with reference to FIGS. 14 to 16. The liquid heater F is a heating device for filling a fluid. A tank 41, the heat transfer tube unit D laterally placed in the heating tank 41, a thermal fluid generator 42 for feeding hot gas into the heat transfer tube unit D as a heat source fluid, and a heat transfer tube unit D.
A gas guide 43 for guiding the exhaust gas discharged from the housing is housed in the frame body 44, and a cock 45 for discharging the fluid is arranged below the heating tank 41.

A contact convection type heat transfer tube 10 according to the present invention integrally includes a cylindrical outer heat transfer plate 20 shown in FIGS. 4 to 6 and an inner heat transfer plate 30 shown in FIGS. 7 to 9. Is made of.

The outer heat transfer plate 20 is provided with a cutout portion 21 formed by cutting out the lower portion of the tubular body along the longitudinal direction as shown in each of the drawings, and a small opening 22 is formed at the position of the cutout portion 21. Made up of.

On the other hand, as shown in FIGS. 7 to 9, the inner heat transfer plate 30 forming the downward concave portion has a main member 31 having an inverted U-shaped cross section perpendicular to the axis and both ends of the main member 31. End members 32a, 32b that are fixed by closing, and a small opening is formed in the center of the central curved portion 31a of the main member 31, and fixed upward by projecting at that portion,
It is constituted by a vertically oriented flow passage 33 that allows the fluid to be heated to flow upward. Further, as shown in FIG. 9, bent portions 34 for joining to the cut edges 21a of the cutout portions 21 of the outer heat transfer plate 20 are formed at both end edge portions of the inverted U shape.

The contact convection type heat transfer tube 10 has an inner heat transfer plate 30 inserted therein along the cutout portion 21 of the outer heat transfer plate 20 to form a cut edge.
21a and the end of the bent portion 34 of the inner heat transfer plate 30 are joined together, and the vertically oriented flow passage 33 is made to look into the small opening 22 of the outer heat transfer plate 20, and the edges are sealed by welding. There is.

As shown in FIGS. 1 to 3, the heat transfer tube unit D has a heat transfer tube 1 arranged in the center, heat transfer tubes 10 according to the present invention arranged on the left and right, and FIGS. 10 and 11 at the tail. 1 and a rear second pipe header 3 that encloses the peripheral edge of the pipe curing body 2. A branch guide member 4 for dividing the heat source fluid into right and left is provided in the central portion of the pipe header 3. Circular tube offset holes 2a into which the heat transfer tubes are fitted are opened at intervals in the tube header 2.

In order to arrange the heat transfer tube unit D in the heating tank 41 of the heater P, the side wall plate of the heating tank 41 on the side of the thermal fluid generator 42 is provided with the tube shift hole 2a of the pipe shifter 2.

In the heat transfer tube 10 in the present embodiment, the inner heat transfer plate 30 forming the downward concave portion has one mountain, but the heat transfer area is expanded,
In order to further increase the heat transfer efficiency, it is possible to have a plurality of peaks depending on the pipe diameter.

Further, if necessary, a plurality of vertically oriented flow passages 33 can be provided corresponding to the pipe length.

Next, the operation will be described.

When the heat source fluid is supplied to the heater F, the heat source fluid (hereinafter referred to as hot gas) is blown into the heat transfer tube 1 of the heat transfer unit D. The heat transfer tube 1 transfers the heat from the hot gas flowing inside to the fluid on the outer circumference, and also guides the hot gas inside to the tail end 2 of the tail end. The hot gas is branched left and right by the branch guide member 4 in the portion, and the contact convection type heat transfer tube according to the present invention is provided.
Flows to 10. In some cases, there is only one direction without branching.

In the contact convection type heat transfer tube 10, the outer heat transfer plate 20 has a heat transfer area substantially equal to that of the heat transfer tube 1 having the same diameter and circular cross section, and the inner heat transfer plate 30 also has the outer heat transfer plate. Since it has an area obtained by adding the heat transfer area of 20, the amount of exchange heat given to the fluid to be heated as a whole significantly increases. Moreover, the hot gas flow cross-sectional area is smaller than that of the circular cross section, and the flow velocity does not decrease.

Further, the inner heat transfer plate 30 has a heat transfer wall that is open downward and that faces upward, and a central flow path 31a is provided with a vertically oriented flow passage 33 that allows the fluid to be heated to flow upward.
Therefore, the heated object to be heated rises through the flow passage 33, and the rising heated fluid stirs the surrounding heated fluid and does not stay in the concave portion of the inner heat transfer plate 30.

The hot gas that has completed the heat transfer action becomes exhaust gas and becomes a heater F.
The gas is discharged toward the upper surface of the fluid from the nozzle 47 at the upper end through the gas guide 43 provided at the rear part.

17 and 18 show another embodiment of the present invention.

In this case, the heat transfer tube unit D ₁ includes the straight tube section 50 and the curved tube section 51.
And have multiple openings along each of the parallel planes.
Repeating turns, the upper and lower ends are connecting pipes 52, 53
Are connected in series with each straight pipe section 50, 50, 50 ...
Are provided with contact convection type heat transfer tubes 10, 10, 10 ... In which fluid guide members 33, 33 are arranged at two positions respectively, and the heat transfer tubes 10, 10 vertically adjacent to each other are arranged in a zigzag pattern. It is designed to improve the efficiency of heat transfer.

The present invention is not limited to the above embodiment,
It can be widely applied to air, water, oil and other gases and liquids as the fluid to be heated.

(Effect of the Invention) According to the heat transfer tube of the present invention, since the vertically oriented flow passage that allows the heated fluid to flow above the outer heat transfer plate is provided in the substantially central portion of the recess, the heat source fluid is The heat transfer is smoothly performed without staying, and the amount of heat exchanged can be significantly increased.

Further, since the heat source fluid does not stay due to the vertically oriented flow path provided in the substantially central portion, deformation due to local heating can be prevented in advance.

Further, it is possible to positively discharge and distribute the heat to the upper side of the outer heat transfer plate through the vertically oriented flow path provided in the substantially central portion, and circulate the heated fluid to stir the whole.

[Brief description of drawings]

FIG. 1 is a front sectional view of a heat transfer tube unit in which a contact convection type heat transfer tube according to the present invention is arranged, FIG. 2 is a plan view of the same, FIG. 3 is a side view of the same, and FIG. FIG. 5 is a bottom view of the outer heat transfer plate of the heat pipe, FIG.
-I sectional view, FIG. 7 is a side view of the inner heat transfer plate, FIG. 8 is a bottom view of the same, FIG. 9 is a sectional view taken along line II-II in FIG. 7, and FIG. Fig. 11, Fig. 11 is the same plan view including the III-III cross section of Fig. 10, Fig. 12 is the front view of the second header,
13 is a plan view including a partial cross section, FIG. 14 is a front view of a fluid heater, FIG. 15 is the same plan view, FIG. 16 is a vertical side view, and FIG.
FIG. 18 is a front view showing another embodiment of the present invention, and FIG. 18 is a IV-IV arrow view of FIG. 10 …… Contact convection type heat transfer tube, 20 …… Outside heat transfer plate, 21 ……
Notch, 30 ... Inner heat transfer plate (constituting downward recess), 31 ... Main member, 33 ... Vertical flow passage.

Claims (1)

[Claims] 1. In a heat transfer tube which is disposed laterally in a heating tank and through which a heat source fluid is circulated to heat a fluid to be heated in the heating tank, a lower portion of a cylindrical body is cut out along a longitudinal direction. And an outer heat transfer plate having a cutout portion, which is connected so as to close the cutout portion, protrudes upward into the outer heat transfer plate, and has a downward concave portion continuous along the longitudinal direction of the outer heat transfer plate. A contact convection type heat transfer tube, comprising: an inner heat transfer plate to be formed; and a vertically oriented flow passage that penetrates above the outer heat transfer plate from a substantially central portion in the recess.