JP2004294010A - Heat exchanger and fin tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten the thermal efficiency of a secondary heat exchanger in a heat exchanger of a gas hot water supply heater including a primary heat exchanger and a secondary heat exchanger. <P>SOLUTION: In a fin tube 6 of the secondary heat exchanger 4 disposed above the primary heat exchanger 3, circular flange-like fins 62 making a turn around the tube is projected at substantially equal spaces on the outer periphery of a metal tube 61 in the longitudinal direction of the tube 61. Each fin 62 is a hollow body integrally connected to the tube. The sectional shape of the fin 62 is such that the outer peripheral edge is pointed substantially triangular, and the inside of the fin is connected to the inside of the tube. Even if on the surface of the fin tube, water in exhaust gas is condensed to cause dew condensation, water drops adhering to the fin are collected at the lower end of the fins through the fins and quickly dropped from the tips of the pointed fins. Accordingly, the water drops can be prevented from remaining on the surfaces of the fins for a long time to lower the heat exchange efficiency of the fins. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Field of the Invention]
TECHNICAL FIELD The present invention relates to a heat exchange device for converting water into hot water and a fin tube used for the heat exchange device.
[0002]
[Prior art]
FIG. 1 shows a heat exchange device (1) which is recently implemented as a heat source device of a household gas hot water supply / room heater.
The heat exchanger (1) has a primary heat exchanger (3) above a gas burner (20) and a secondary heat exchanger (4) above the primary heat exchanger, and is provided with a water pipe (5). Water is led from the secondary heat exchanger (4) to the primary heat exchanger (3).
In the water pipe passing through the secondary heat exchanger (4), as shown in FIG. 3, fins (60) are formed at equal intervals in the length direction of the pipe to increase the surface area of the pipe.
The water pipe passing through the primary heat exchanger (3) passes through a row of metal heat absorbing plates (33) arranged in parallel.
[0003]
The temperature of the combustion exhaust gas from the gas burner (20) is about 1500 ° C near the burner, about 200 ° C near the primary heat exchanger (3), and about 80 ° C near the secondary heat exchanger (4).
In the heat exchanger before the heat exchanger (1), the secondary heat exchanger (4) does not exist, and the temperature of the flue gas rising through the primary heat exchanger (3) is effectively used. I didn't.
The heat exchange device (1) in FIG. 1 can preliminarily heat water by effectively utilizing the temperature of the flue gas rising through the primary heat exchanger (3) in the secondary heat exchanger (4). Therefore, thermal efficiency can be improved.
[0004]
However, water in the combustion exhaust gas condenses on the fin tubes (6) of the secondary heat exchanger (4), and water droplets adhere.
The fin (60) of the conventional fin tube (6) has a semicircular cross-sectional shape in a plane including the tube axis, makes it difficult for attached water droplets to fall, and reduces the time during which it adheres to the surface of the fin (62). long. For this reason, there was a problem that the heat exchange efficiency of the secondary heat exchanger (4) was reduced.
[0005]
The present invention clarifies a fin tube and a heat exchange device using the fin tube that can solve the above-described problem by devising the shape of the fin of the fin tube.
[0006]
[Means to solve the problem]
The fin tube (6) of the present invention comprises a metal tube (61) and a fin tube (6) in which circular flange-shaped fins (62) surrounding the tube protrude at substantially equal intervals in the longitudinal direction of the tube (61). ), The fin (62) is a hollow body continuous with the pipe, and the cross-sectional shape of the fin (62) in a plane including the axis of the pipe (61) has a substantially triangular outer peripheral edge. The inside of the fin is continuous with the inside of the tube.
[0007]
The heat exchanger of the present invention has a primary heat exchanger (3) disposed above a heating source such as a burner (20) and a secondary heat exchanger (4) disposed above the primary heat exchanger. The above-mentioned fin tube is implemented in the secondary heat exchanger (4). Water is led to the primary heat exchanger (3) via the secondary heat exchanger (4).
[0008]
[Action and effect]
Even if the moisture of the outside air including the combustion exhaust gas condenses on the surface of the fin tube (6) and dew condensation occurs, water droplets attached to the fin (62) travel along the fin (62) to reach the lower end of the fin (62). get together. Since the fin (62) is sharp to the outer peripheral side, the drainage is good, and the water droplet drops from the fin tube (6) without staying at the fin (62) for a long time.
Therefore, it is possible to suppress a decrease in the heat exchange efficiency of the fin due to a group of water droplets remaining on the fin surface for a long time as in the related art.
Further, since the fin (62) is a hollow body and is continuous inside the pipe (61), the efficiency of heat exchange between the water passing through the pipe and the fin can be increased.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The basic configuration of the heat exchanger of the present invention is the same as that of the conventional heat exchanger (1) having the primary heat exchanger (3) and the secondary heat exchanger (4) described with reference to FIG. .
To make up for the lack of explanation in the conventional example, the primary heat exchanger (3) and the secondary heat exchanger (4) are surrounded by housing covers (31) and (41) whose upper and lower surfaces are respectively opened.
Inward flanges (32) and (42) project from lower ends of both covers (31) and (41), and drain pipes (34) and (44) are connected to the inward flanges (32) and (42). Both drain pipes (34) and (44) are led to the neutralizer (7).
The neutralizer (7) adheres to the inner surfaces of the covers (31) and (41), drops on the flanges (32) and (42), and is guided into the neutralizer (7) through the drain pipes (34) and (44). It serves to neutralize and discharge the acidic condensed water.
The heat exchange device (1) is covered with a housing (11).
[0010]
A feature of the invention lies in the fin tubes (6) passing through the secondary heat exchanger (4).
As shown in FIG. 2A, the fin tube (6) is formed by forming a circular flange-like fin (62) around the metal tube (61) around the metal tube (61) at substantially regular intervals in the length direction of the tube (61). It is protruding.
Each fin (62) is a hollow body that is integrally continuous with the tube (61), and as shown in FIG. 2b, the cross-sectional shape of the fin (62) on the plane including the axis of the tube (61) is outside. The periphery is pointed in a substantially triangular shape.
The opposed annular side walls of each fin (62) bulge outwardly in a slightly arcuate shape, and the side walls are provided with annular shallow recesses (63) (63) centered on the axis of the tube. ).
[0011]
The fin tube (6) of the embodiment has excellent heat resistance and rust resistance, has good thermal conductivity, and is formed of a metal which can be subjected to fin pressure molding described later, for example, titanium, stainless steel, or the like.
The fin tube (6) of the embodiment has a minimum outer diameter of 16 mm, a maximum outer diameter of 22.5 mm, and a fin pitch of 3 mm and a pitch of 4.4 mm.
[0012]
However, even if water in the flue gas of the burner (20) condenses and dew condensation occurs on the surface of the fin tube (6) of the secondary heat exchanger (4), water droplets adhering to the fin (62) are It gathers at the lower end of the fin (62) along the fin (62). Since the fins (62) are sharp to the outer peripheral side, the drainage is good and the water drops fall without staying on the fins for a long time.
Therefore, it is possible to suppress a decrease in the heat exchange efficiency of the fin (62) due to a group of water droplets remaining on the fin surface for a long time as in the related art.
[0013]
In addition, the opposing side surfaces of the fin (62) bulge round and the concave portions (63) (63) surrounding the fin (62) are formed, so that the surface area of the fin (62) increases, and the heat absorption efficiency increases. Can be increased.
Further, since the fin (62) is a hollow body and is continuous inside the pipe (61), the efficiency of heat exchange between the water passing through the pipe and the fin can be increased.
[0014]
In addition, in the primary heat exchanger (3), since the surrounding temperature is high, dew condensation does not occur in the tubes.
[0015]
In carrying out the present invention, the heating source (2) is not limited to the gas burner (20), and may be of any type as long as it utilizes the high temperature of the combustion gas.
[0016]
The description of the above embodiments is intended to explain the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a heat exchange device provided with a secondary heat exchanger.
FIG. 2a shows a fin tube, and shows a cross section of the tube from above the center line.
FIG. b is an enlarged sectional view of the fin.
FIG. 3 shows a cross-sectional shape of a conventional fin.
[Explanation of symbols]
(1) Heat exchanger (2) Heat source (3) Primary heat exchanger (4) Secondary heat exchanger (5) Water pipe (6) Fin pipe (61) Metal pipe (62) Fin

Claims (3)

A fin tube (6) in which a circular flange-shaped fin (62) surrounding the metal tube (61) projects around the tube at substantially equal intervals in the length direction of the tube (61), (62) is a hollow body which is continuous with the pipe, and the cross-sectional shape of the fin (62) on the plane including the axis of the pipe (61) has a substantially triangular outer peripheral edge. The inside is a fin tube that is continuous inside the tube. The opposite annular side wall of each fin (62) bulges outward in a slightly arc shape, and the side wall has an annular shallow recess (63) (63) centered on the axis of the pipe as a radial center. The fin tube according to claim 1, wherein the fin tube is formed so as to make a full circle. A primary heat exchanger (3) is provided above a combustion heating source (2) such as a gas burner, and a secondary heat exchanger (4) is provided above the primary heat exchanger. Water is supplied to the secondary heat exchanger (4). 3. A fin tube (6) according to claim 1 or 2, wherein the fin tube (6) according to claim 1 or 2 is fed to the primary heat exchanger (3) by feeding water preheated by the secondary heat exchanger (4). The heat exchange device implemented in (4).

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