JPS6127666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a water-gas heat exchanger that heats two independent systems on the water side with kerosene-fired or gas-fired fuel gas.

Examples of the use of a heat exchanger that heats two independent water system channels include household heating systems, hot water heaters, and bathtubs. That is, by circulating water through two independent systems and heating it with combustion gas, for example, in the case of a bath, hot water for upstream heating and hot water for bathtub use are obtained and used for each purpose. In such a heat exchanger having two independent water channels, water does not necessarily circulate in both at the same time, but at least one of the circulating water is stationary. In this case, if the two systems are separated, the water temperature in the stationary one will become extremely high, increasing the pressure in the flow path and causing the water to boil, making proper operation impossible. Become. Therefore, conventionally,
As a heat exchanger with two systems, two sets were installed independently: a heat exchanger and burner unit to heat the water stored in the bathtub, and a heat exchanger and burner unit to heat the rising temperature. 2
There is a circuit bath kettle. Since this bathtub has two heat exchangers and two burner units inside, it has the drawback that its external dimensions are large and its cost is high. To solve this drawback, there is a one-pot, two-circuit bathtub. That is, since the flow path for boiling hot water and the flow path for rising hot water are combined into one heat exchanger and only one burner unit is required, the external dimensions can be reduced and costs can be reduced.

Figures 1 and 2 show a specific example of a bath heat exchanger, in which pipe pieces 1a and 1b each having a U-shaped cross section are brazed to create a flow path 2 with a rectangular cross section.
are arranged in six rows to form parallel channels 21, 2.
2, 23, 24, 25, and 26, both ends of which are connected to mixing chambers 3, 4, and one mixing chamber 3 is connected to a bathtub water inlet/outlet with pipes 5, 6 to form a water flow path for boiling water. In addition, circular tubes 91, 92, 93, which are spaced apart from each other and attached to a common heat dissipation fin 8 under the rectangular cross-sectional flow path,
. . . are connected in series using six (two not shown) U-shaped pipes 10 to form an upstream hot water shower flow path.

However, in a heat exchanger with this type of structure, the hot water flow path and the upstream hot water shower flow path are provided separately and heated by a common burner unit, so as mentioned above, one of the flow paths is stationary. Then, the water in the flow path is always in a high-temperature boiling state, and the pressure in the flow path increases, making it impossible to operate properly. In order to prevent such a situation, water is drained from the stationary flow path, or both flow paths are thermally connected using heat dissipation fins.

In the former case, in addition to the heat exchanger, an attached equipment called a water drainage mechanism is required, and in the latter case, the stationary flow path is cooled by flowing water through a heat radiation fin, which results in poor fin efficiency. If the number of fins increases or the area of the fins increases, the heat exchanger becomes larger. Further, even if a large number of fins are provided, cooling is not sufficient, and in this case as well, water is removed. Furthermore, since the pipe 1 for boiling hot water has a rectangular shape, the manufacturing process is complicated and it is difficult to fit the pipe 1 in close contact with the fin.

In order to solve the above-mentioned drawbacks, the present invention has provided a plurality of heat exchange pipes each having an inner tube inserted therein so as to divide the radial direction of the outer tube in a substantially central portion of the circular outer tube. are connected to each mixing chamber to form a parallel flow path, and the outer tube is molded so as to be in close contact with the inner tube, which has a circular cross section at the tube end, and the adjacent outer tube flow paths are connected to each other by a U-shaped tube. By connecting them in series, a heat exchanger that is easy to manufacture and has high performance is provided.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 3 shows an embodiment of the present invention, and FIG. 4 is a cross-sectional view of the main part of FIG. 3 as viewed in the X-Y direction.

In other words, if the structure and operation are explained using an example of use as a bath heat exchanger, 100, 101, 102
is an outer tube inserted into a large number of plate-shaped heat dissipation fins 103, and inside each of the outer tubes 100, 101, 102, the radial direction of the outer tube is divided approximately at the center to provide arcuate contact surfaces A, B. to form an outer tube flow path 104,
Inner tubes 106, 107, 108 having 105 are inserted.

Both ends of the inner tube have a circular cross section and each have a mixing chamber 11.
0 and 111 to form a parallel flow path and serve as a wakashiyu flow path. The end of the outer tube is drawn so as to be in close contact with the end of the inner tube, which has a circular cross section, and the ends of the adjacent outer tubes 100, 101, 102 are connected in series with U-shaped tubes 122, 123 to form an inlet. The pipe 124 and the discharge pipe 125 are connected in series to form a hot water flow path. This heat exchanger is tilted from the horizontal in the longitudinal direction (angle of inclination θ = 10 to 30 degrees) to form a mixing chamber 11.
When 0 is the lower side, this mixing chamber 110 is connected to the hot water inlet (not shown) of the bathtub through a pipe 112, and the mixing chamber 111 is connected to the hot water outlet (not shown) through a pipe 113. . As a result, the mixing chamber 111 can be made 100 to 200 mm higher than the mixing chamber 110.
The water in the bathtub can be heated by circulating water using natural convection.

Next, the operation of the present invention will be explained. In the wakashiyu operation, water is passed through the inner pipe and water flow through the upstream shower flow path of the outer pipe is stopped, but the inner pipes 100, 101, 102 and parts of the outer pipes 106, 107, 108 are brought into contact with each other. Therefore, the amount of heat transferred from the combustion gas via the heat dissipation fins 103 is transferred to the inner tube water through the contact parts A and B between the inner tube and the outer tube. Provides heat exchange performance. Further, as described above, by slanting in the longitudinal direction, a sufficient amount of water can be circulated by natural convection.

On the other hand, in the upstream hot water shower operation, water is passed through the outer pipe flow path, so sufficient heat exchange performance can be obtained without being affected by whether the inner pipe is filled with water (wakashi hot water) or empty. In particular, even when there is no hot water in the shower, the hot water flow path does not reach a higher temperature than the upstream shower water, allowing safe operation. Furthermore, when boiling hot water is contained, part of the heat transferred from the combustion gas is transferred to the boiling water, but this amount of heat is sufficiently small if the contact area between the inner tube and the outer tube is as described above.

In other words, if the hot water shower is operated for 15 minutes, as shown in Figure 5, if the total heat exchange amount is less than 10,000 Kcal/h, the proportion of heat transferred to the outer pipe water can be sufficiently reduced.
The rise in water temperature in the bathtub can be suppressed to about 1.5°C or less, making it sufficiently safe for practical use.

In addition, Figure 5 shows a bathtub water volume of 0.2 m ² and a pipe of 3.
Book, l=300mm, outer tube t=30mm, inner tube t=23mm,
These are the characteristics when the flow path area ratio outer tube/inner tube = 23/30.

Next, a modification of the heat exchanger of the present invention will be explained with reference to FIG. Note that the same parts in FIG. 3 are designated by the same reference numerals and detailed explanations will be omitted. That is, it shows the structure of the tube ends of the outer tubes and the connecting portions between adjacent outer tubes. In Figures 3 and 4, the outer tube is formed into a draw shape so that the tube end is in close contact with the outer surface of the inner tube.
In this modification, a connecting sleeve 130 is used, and an outer tube connecting sleeve 124 is formed so that the end of the outer tube 130 is inserted into one end and the other end circumscribes the outer surface of the inner tube.
One end of the U-shaped tube 122 is inserted into a circular hole bored in the body of the U-shaped tube 122 to form a serial flow path. By using such an outer tube connecting sleeve, the outer tube flow path area at the tube end can be increased, and the flow resistance of the outer tube water can be reduced.

As explained above, according to the heat exchanger according to the present invention, sufficient and safe thermal performance can be obtained by using the pipes inserted into the circular tube in a radially divided manner. Because the outer tube is circular, it is in close contact with the heat dissipation fins, and the area of the heat dissipation fins is only needed for one unit, reducing costs.The structure is suitable for mass production, as it is easy to manufacture and requires few brazing processes. It has the following.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a conventional bath heat exchanger, FIG. 2 is a vertical sectional view of the main part of FIG. 1, and FIG. 3 is a part of an embodiment of the present invention. Fig. 4 is a longitudinal sectional view of the main part of Fig. 3;
FIG. 5 is a characteristic diagram showing the temperature rise of bathtub water with respect to changes in heat quantity according to the present invention, and FIG. 6 is a longitudinal sectional view of a main part showing a modification of the present invention. In addition, 100, 101, 102 are outer tubes, 103
are heat radiation fins, 104 and 105 are outer tube flow paths, and 10
6, 107, 108 are inner pipes, 122, 123 are U
110, 111 are mixing chambers, 112, 113
is a pipe.

Claims (1)

[Claims] 1. Within a circular outer tube forming one independent flow path with heat dissipation fins provided on the outer peripheral surface, at least two arcuate contact surfaces are formed along the axial direction of the outer tube to form the other independent flow path. A plurality of heat exchange pipes each having inner pipes inserted therein forming The outer tube is molded and sealed in close contact with the inner tube, which has a circular cross section, at the end of the tube, and the adjacent outer tube flow paths are connected in a U-shape so that they do not touch the inner tube flow path. A heat exchanger characterized by being connected in series with tubes.