JPH0567863B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat exchanger used for heating water.

[Conventional technology]

In many conventional heat exchangers such as household water heaters and instantaneous water heaters, the fins necessary for heat exchange are made of materials such as aluminum or copper that have relatively poor heat resistance. The heat exchanger fins are aluminum,
If it is made of stainless steel, copper, etc., there is a risk of the part adjacent to the combustor being fused, so the combustion gas is mixed with air and cooled to some extent before being introduced into the heat exchanger.

However, in the above-mentioned heat exchanger, it is necessary to increase the heat transfer area by the temperature reduction of the combustion gas, and the shape becomes large. Therefore, if the temperature of the part of the heat exchanger that comes into contact with the combustion gas, especially the part adjacent to the combustor, is made relatively low, the heat exchange area must be increased accordingly, which reduces the overall size of the heat exchanger. invites change.

For example, as disclosed in Japanese Utility Model Application Publication No. 55-417265, in order to lower the temperature near the combustor, part of the combustion gas that has passed through the heat exchanger is recirculated toward the combustor to generate new combustion. Although it has been proposed to mix it with gas and send it back to the heat exchanger, there is a limit to the temperature reduction of the combustion gas. In addition, if the heat exchanger receives combustion gas in a dry state where it does not receive liquid, there have been problems such as melting and damage of the welded parts of the heat exchanger.

[Problem to be solved by the invention]

Therefore, the purpose of the present invention is to make the whole compact,
The object of the present invention is to provide a heat exchanger that is simple in configuration, has high thermal efficiency, and can withstand dry cooking.

[Means to solve the problem]

In order to achieve the above object, the configuration of the present invention is as follows:
A cylindrical ceramic honeycomb structure is fitted into an outer cylinder having an exhaust pipe at the upper end and a bottom at the lower end to form a large number of combustion gas passages. A plurality of intake ports are provided at intervals, a combustor is provided in the empty space between the honeycomb structure and the bottom of the outer cylinder to form a combustion chamber, and a water intake port and a combustor are provided inside the honeycomb structure. A double water pipe consisting of an inner water pipe that communicates with the water pipe and an outer water pipe that communicates with the hot water supply port and has a ceramic honeycomb structure inside is inserted from the bottom of the outer cylinder.

[Effect]

High-temperature combustion gas from the combustor is supplied to the honeycomb structure, passes between the fins of the honeycomb structure, and is discharged to the outside from the exhaust stack. Water introduced from the water inlet flows upward through the passage of the inner water pipe and turns around at the cap. Water is heated as it flows down inside the honeycomb structure of the outer water pipe, and is supplied to the outside from the hot water supply port. The honeycomb structure has excellent heat resistance, so a combustor is installed at one end of the honeycomb structure.
It can be placed close to the position where the flame temperature is the highest, making it possible to improve thermal efficiency and downsize the heat exchanger.

[Embodiments of the invention]

As shown in FIGS. 1 and 2, the heat exchanger 6 according to the present invention has an outer cylinder 12 whose lower end is closed by a bottom 12a and whose upper end is constricted, forming an exhaust pipe 7. A combustion chamber 20 is formed in an empty space between a honeycomb structure 2 and a bottom 12a, which will be described later, in the outer cylinder 12, and a plurality of intake ports 13 are provided at intervals in the circumferential direction on the side wall of the lower end. Combustion chamber 2 of outer cylinder 12
A combustor 14 is disposed at 0. The combustor 14 is connected to a fuel tank (not shown) via a fuel pipe 16 protruding from the outer cylinder 12 to the outside.

An outer water tube 18, which is an outer tube of a double water tube that penetrates through the center, is connected to the bottom 12a of the outer tube 12, and a cap made of ceramics such as silicon carbide, metal, etc. is fitted onto the upper end of the outer tube 18. Closed. The cap 8 is liquid-tightly connected to the outer water pipe 18 by providing a metallized layer 9 on its inner surface or by interposing a metal sealing member. A joint 19 is connected to the lower end of the outer water pipe 18. The end wall of the joint 19 is integrally connected to the lower end of the inner water pipe 17, which is the inner pipe of the double water pipe. A gap is provided between the upper end of the inner water pipe 17 and the cap 8. The lower end of the inner water pipe 17 constitutes a water supply port 17a to which a water pipe or the like is connected, for example. The joint 19 is provided with a hot water supply port 15 on its peripheral wall, and the hot water supply port 15 is connected to a conduit if necessary.

According to the present invention, in order to protect the outer water tube 18 surrounded by the combustor 14 from high temperatures, the honeycomb structure 2 made of ceramics as a heat exchanger is connected to the outer tube 12 immediately above the combustor 14 and the outer water tube. It is accommodated between 18 and 18. Honeycomb structure 2
It is desirable to fit into the inner circumferential surface of the outer cylinder 12 via a suitable heat insulating material. Similarly, a honeycomb structure 10 made of ceramics is disposed between the outer water pipe 18 and the inner water pipe 17 of the double water pipe.

As shown in FIG. 2, the heat exchange section is composed of ceramic honeycomb structures 10 and 2 with fins, and includes a passage through which water passes and a passage through which high-temperature combustion gas passes. In other words, both are separated by a cylindrical partition wall having a size of one-half or less of the outer diameter of the heat exchanger, that is, an outer water pipe 18 made of a heat-resistant metal such as ceramics or stainless steel. The combustor 14 uses gaseous fuel or liquid fuel as fuel,
It is arranged close to the lower end side of the honeycomb structure 2.

With the above configuration, the present invention can provide a small heat exchanger, specifically a water heater, in which the outer cylinder 12 has an outer diameter of 100 mm and a length of 200 mm, for example. The fins of the honeycomb structures 2 and 10 have a thickness of about 0.5 to 1.0 mm, and the gap between the fins is 1.5 to 2.5 mm. When the void ratio occupied by the honeycomb structures 2 and 10 is calculated from this dimension, the void ratio is 36 to 69.4%.

In the present invention, the thickness of the fins of the honeycomb structures 2 and 10 is limited to 0.5 to 1.0 mm.
If it is less than 0.5mm, there will be problems in terms of heat resistance and strength.
On the other hand, if the thickness exceeds 1.0 mm, the porosity cannot be set sufficiently and the heat exchange efficiency decreases.

Similarly, if the gap between the fins is less than 1.5mm,
The pressure loss of the high-temperature combustion gas increases, the temperature near the combustor becomes abnormally high, and there is a risk that the honeycomb structures 2 and 10 will be melted and damaged. Furthermore, if the distance between the fins exceeds 2.5 mm, the heat exchange efficiency will decrease, which is not preferable.

Next, the operation of the heat exchanger according to the present invention will be explained.

The high temperature combustion gas of the combustor 14 is transferred to the honeycomb structure 2
and is discharged to the outside from the exhaust pipe 7 after passing between the fins. On the other hand, water introduced into the water supply port 17a of the joint 19 flows upward through the passage 3 of the inner water pipe 17 of the double water pipe, turns back at the cap 8, and flows down inside the honeycomb structure 10 of the outer water pipe 18. do. Water is heated while passing between the fins of the honeycomb structure 10, and is supplied to the outside from the hot water supply port 15.

According to the present invention, so that the fuel is completely combusted,
By supplying a mixture with a preset air-fuel ratio to the combustor 14, the combustor 14 can be placed sufficiently close to the heat exchanger, and even if the combustion condition deteriorates slightly, fresh air can be supplied from the intake port 13. Therefore, incomplete combustion can be prevented.

Between the cap 8 and the outer water pipe 18 where water is sent back from the inner water pipe 17 to the outer water pipe 18, a seal layer 9 made of metallized silicon carbide or a seal layer formed by press-fitting a metal seal in the middle is provided. Since the honeycomb structure is attached to the outer peripheral surface of the cap 12 via a heat insulating material, it is possible to prevent the fitting portion of the cap 8 from being melted and the outer cylinder 12 from being heated.

〔Effect of the invention〕

As described above, the present invention includes a cylindrical ceramic honeycomb structure fitted inside an outer cylinder having an exhaust pipe at the upper end to form a large number of combustion gas passages,
A plurality of intake ports are provided at intervals in the circumferential direction of the lower end of the outer cylinder, and a combustor is disposed in the empty space between the honeycomb structure and the bottom of the outer cylinder to form a combustion chamber, and the honeycomb structure A double water pipe consisting of an inner water pipe that communicates with the water supply port and an outer water pipe that communicates with the hot water supply port and has a ceramic honeycomb structure on the inside is inserted into the body from the bottom of the outer cylinder. Therefore, the following effects are achieved.

The heat exchange section is constructed by inserting a double water tube consisting of an outer water tube and an inner water tube into the honeycomb structure, which is inserted into the outer tube from the bottom of the outer tube, so the structure of the heat exchanger is It is simple, easy to manufacture, and easy to assemble.

Since ceramic honeycomb structures are provided inside and outside the outer water pipe, heat exchange is performed smoothly and heat exchange efficiency can be improved.

Since the ceramic honeycomb structure has excellent heat resistance, the honeycomb structure can be disposed close to the position where the flame temperature of the combustor is the highest, making it possible to downsize the heat exchanger and improve thermal efficiency.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a heat exchanger according to the present invention,
It is a cross-sectional view of the same plane as FIG. 2. 2, 10...honeycomb structure, 7...exhaust pipe,
12...Outer cylinder, 14...Combustor, 16...Fuel pipe, 17...Inner water pipe, 18...Outer water pipe.

Claims (1)

[Claims] 1 A cylindrical ceramic honeycomb structure is fitted into an outer cylinder having an exhaust pipe at the upper end and a bottom at the lower end to form a large number of combustion gas passages, and the lower end of the outer cylinder is circumferentially A plurality of intake ports are provided at intervals, a combustor is provided in the empty space between the honeycomb structure and the bottom of the outer cylinder to form a combustion chamber, and a water supply port is provided inside the honeycomb structure. A heat exchanger characterized in that a double water pipe consisting of an inner water pipe that communicates with the hot water supply port and an outer water pipe that communicates with the hot water supply port and has a ceramic honeycomb structure inside is fitted from the bottom of the outer cylinder.