JPH0334603Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to a heat exchanger for a hot water storage type water heater using petroleum.

<<Prior art>> Heat exchanger 1 used in a conventional hot water storage type water heater
As shown in FIGS. 6 and 7, the water supply pipe 6
The upper tank 2 and the lower header 3 to which the hot water outlet pipe 7 is attached are connected by a heat receiving pipe 5 provided with fins 4.
The heat-receiving pipes on the inside of the ... are used as riser pipes 5b that flow water from the lower header 3 to the upper tank 2, and the heat-receiving pipes on the left and right sides have smaller fin areas than the riser pipes 5b, and flow from the upper tank 2 to the lower header 3. It is formed as a downstream pipe 5a through which water flows to.

In addition, the water supply pipe 6 is connected to a water distribution pipe 20 within the upper tank 2.
Injection pipes 21, 21, which are connected to the water distribution pipe 20 and protrude from the water distribution pipe 20, are configured to be injected into the inlets of the left and right outer downstream pipes 5a, 5a.

The schematic structure of a water heater using the heat exchanger 1 is as shown in FIG. It is fixed within the combustion chamber 8 to which the burner section 13 is attached. Water is supplied from a tap or the like via the pressure reducing valve 14 of the water supply pipe 6, passes through the heat exchanger 1, and reaches the hot water tap 15.
Then, when the operation switch 17 of the operation section 16 is turned on, if the temperature detected by the temperature sensor 18 provided in the heat exchanger 1 is lower than a predetermined temperature, combustion in the burner section 13 is started according to an instruction from the controller 19. .

When the hot water tap 15 is open, water is supplied to the water distribution pipe 20.
is injected into the left and right outer downstream pipes 5a, 5a through the injection pipes 21, 21, whereby a downward flow is generated in the left and right outer downstream pipes 5a, 5a, and an upward flow is generated in the inner rising pipes 5b, 5b. occurs.

Further, when the hot water tap 15 is closed and the inside of the heat exchanger 1 is water or relatively low-temperature water, the inner riser pipes 5b, 5b have a larger fin area than the left and right outer downstream pipes 5a, 5a. Due to the large heat load, an upward flow occurs in the inner riser pipes 5b, 5b, and an upward flow occurs in the left and right outer downstream pipes 5a, 5a.
A downward flow occurs, and as a result, the water temperature inside the upper tank 2 of the heat exchanger 1 increases.

<<Problem to be solved by the invention>> In the heat exchanger described above, if the hot water tap is opened while the water inside the heat exchanger is boiling to a high temperature, and the temperature sensor detects a low temperature while hot water is being supplied, The burner section starts combustion, but if the hot water tap is closed just before the burner section starts combustion, that is, if the burner section starts combustion immediately after the hot water tap is closed, local boiling will occur inside the heat exchanger. A phenomenon occurs.
This state will be explained with reference to the explanatory diagrams of FIGS. 4a to 4c. Figure 4a shows the case where the hot water tap is opened in the state of hot water. In this case, water is injected into the hot water, and the water flows through the U formed by the downstream pipe and the rising pipe.
It flows through the tube from the downstream pipe to the rising pipe, mixing with high-temperature hot water. FIG. 4b shows the case where the hot water tap is closed. When the hot water tap is closed, the flow inside the heat exchanger disappears and the water stops. At this time, when the burner starts combustion and the heat receiving pipe receives heat, the temperature of the water in the heat receiving pipe rises rapidly as shown in Figure c, and the draft force causes the heat receiving pipes on both sides of the U-shaped tube to rise. The water inside both a certain downstream pipe and an ascending pipe tries to rise in the direction of the broken line arrow, resulting in a blocked state. Moreover, since both heat receiving pipes are originally high-temperature hot water, the boiling temperature is reached before the normal flow from the downstream pipe to the riser pipe is established, and a local boiling phenomenon occurs in the downstream pipe and the riser pipe. When this localized boiling phenomenon occurs, unpleasant noises are generated due to the water hammer phenomenon, etc., and users and nearby residents are bothered by this unpleasant noise, and the lifespan of the heat exchanger is also significantly shortened. There is.

<Means for solving the problem> In order to solve the above problem, in the present invention, the upper tank and the lower header, to which the water supply pipe and the hot water outlet pipe are attached, are connected by a plurality of heat receiving pipes with fins. A part of the heat receiving pipe is formed as a rising pipe for water to flow from the lower header to the upper tank, and the other heat receiving pipe is formed to have a smaller fin area than the rising pipe, and a downstream pipe for water to flow from the upper tank to the lower header. In the heat exchanger, a water distribution pipe branching from the water supply pipe is installed in the upper tank, and an injection pipe protruding from the water supply pipe faces the inlet of the downstream pipe. It is characterized by having an outflow hole nearby that allows water to flow out into the upper tank.

<<Operation>> When the burner section starts combustion immediately after the hot water tap 14 is closed, the water in the upper tank remains stationary. At this time, when the burner section starts combustion, draft force is generated in the heat receiving pipe due to heating of the downstream pipe and riser pipe, and as a result, hot water tries to rise in the downstream pipe and riser pipe at the same time, resulting in a blockage state and causing a local boiling phenomenon. It occurs, but the fifth
As shown in the figure, an outflow hole is provided in the diversion pipe near the injection pipe, and through this outflow hole, low-temperature water flows out into the upper tank near the downstream pipe inlet, and water near the downstream pipe flows into the downstream pipe. Since the water flows into the heat exchanger and causes a convection phenomenon, the water circulates from the downstream pipe to the riser pipe within the heat exchanger.

<<Description of Embodiments>> Embodiments of this invention will be described in detail below with reference to the drawings. Incidentally, the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 is a plan view of the heat exchanger according to the present invention;
2 and 3 are cross-sectional views showing the structure of the heat exchanger according to the present invention, and FIG. 5 is an explanatory view showing the state of water flowing in the U-shaped tube of the heat exchanger according to the present invention.

In the figure, 1 is a heat exchanger of the present invention used in a water heater, and 2 is a water supply pipe 6 and a hot water outlet pipe 7.
This is an upper tank that functions as a hot water storage tank and an upper header.

3 is a lower header, and this lower header 3
and the upper tank 2 are connected by a heat receiving pipe 5 provided with fins 4 around the periphery.

Four heat-receiving pipes 5 are shown in the figure, and the two on the inner and outer sides are the downstream pipes 5a, 5a, and the two on the inner side are the downstream pipes 5a, 5a. The fins 4 have a larger area (larger diameter) than the fins 4, and the downstream pipes 5a, 5a
The riser pipes 5b, 5b have higher heat transfer performance than the above. In addition, the rising pipes 5b, 5b are the downstream pipes 5
It protrudes into the upper tank 2 with a longer dimension than a and 5a. The water supply pipe 6 is connected to a water distribution pipe 20 in the upper tank 2, and this water supply pipe 20 includes:
Injection pipes 21, 21 for injecting into the inlets of the left and right downstream pipes 5a, 5a are formed to protrude.

22 is an outflow hole provided in the water distribution pipe 20,
This outflow hole 22 is opened near the injection pipe 21 to allow the water supply to flow out into the upper tank 2. The water distribution pipe 20 is brazed and connected to the water supply pipe 6 and the wall surface of the upper tank 2.

Therefore, in the present invention, even if the downstream pipe 5a and the rising pipe 5b are heated and water rises in both pipes at the same time when the hot water tap 15 is turned off, the water diversion pipe 20 is provided with the outflow hole 22. As a result, low-temperature water flows out from the outflow hole 22, water near the downstream pipe 5a flows into the downstream pipe 5a, a convection phenomenon occurs, and the flow from the downstream pipe 5a to the riser pipe 5b is reduced. This will continue.

<<Effects>> As described above, according to the present invention, the outflow hole is provided in the water distribution pipe near the injection pipe, so even if the burner starts burning immediately after the hot water tap is closed, the downstream A convection phenomenon will occur at the upper end of the tube. Therefore, water normally circulates in the heat receiving pipe and upper tank in the heat exchanger from the downstream pipe toward the rising pipe, eliminating blockages and preventing local boiling. , can prevent unpleasant noises caused by water hammer phenomenon, etc.
It also has the effect of extending the life of the heat exchanger.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the heat exchanger according to the present invention;
Figures 2 and 3 are cross-sectional views showing the structure of the heat exchanger according to the present invention, Figures 4 a to c are explanatory diagrams showing the state of water flowing inside the U-shaped pipe, and Figure 5 is the U-shaped pipe according to the present invention. An explanatory diagram showing the flow state in the pipe, FIG. 6 is a plan view showing a conventional heat exchanger, and FIG.
The figure is a sectional view showing the structure of a conventional heat exchanger, and FIG. 8 is an explanatory diagram of the schematic structure of a water heater. 1...Heat exchanger, 2...Upper tank, 3...Lower header, 4...Fin, 5...Heat receiving pipe,
5a... Downstream pipe, 5b... Rising pipe, 6... Water supply pipe, 7... Hot water outlet pipe, 8... Combustion chamber, 20... Water distribution pipe, 21... Injection pipe, 22... Outflow hole, 23
...U-shaped tube.

Claims (1)

[Scope of Claim for Utility Model Registration] An upper tank to which a water supply pipe and hot water outlet pipe are attached and a lower header are connected by a plurality of heat receiving pipes with fins, and a riser pipe through which water flows from a part of the heat receiving pipe from the lower header to the upper tank. The other heat receiving pipe is formed with a smaller fin area than the riser pipe and is formed as a downstream pipe for water to flow from the upper tank to the lower header, and a water distribution pipe branching from the water supply pipe is installed inside the upper tank. In addition, in the heat exchanger in which an injection pipe protruding from the water distribution pipe faces the inlet of the downstream pipe, an outflow hole is provided near the injection pipe of the water distribution pipe to allow water to flow out into the upper tank. A heat exchanger for a hot water storage type water heater.