JPS6326308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger that can be used in general heaters that burn gas or liquid fuel and exchange heat between the combustion gas and indoor air.

Conventionally, this type of heat exchanger is a secondary heat exchanger in which internal fins, external fins, and a flange are integrally formed of aluminum die-casting on the downstream side of the combustion cylinder, as shown in Figures 1 and 2. There are configurations that include equipment.

In FIGS. 1 and 2, 1 is a burner integrated with a combustion fan, 2 is a combustion tube, 3 is a header, 4 is a secondary heat exchanger, and includes an internal fin 5, an external fin 6, and a flange. The portion 7 is integrally formed by aluminum die casting, and the flange portion 7 is fixed to the header 3 via a packing. 8 is a convection blower, and 9 is an outer casing. High-temperature combustion gas burned in the burner 1 undergoes primary heat exchange between the outer surfaces of the combustion tube 2 and the header 3, and then is guided into the secondary heat exchanger 4. At this time, heat is absorbed by the internal fins 5, heat radiation is promoted by the external fins 6, a secondary heat exchange is performed, and the air is exhausted to the outside air.

However, this type of heat exchanger structure had the following drawbacks.

1 As the manufacturing method requires aluminum die-casting, (1) the number, wall thickness, length, etc. of internal fins are regulated due to the flow of metal during die-casting and the draft angle of the mold. Therefore, it is not possible to ensure a sufficient heat transfer area with a small size. Furthermore, the cost of materials was also relatively high.

(2) A large amount of money is required for mold costs, equipment costs, etc., resulting in high production costs.

2. When developing equipment according to heating capacity, new molds are required for each capacity, making it difficult to share heat exchangers.

The present invention eliminates these conventional drawbacks, and the joint between the end of the secondary heat exchanger made of extruded aluminum and the header becomes high in temperature, causing damage due to the stress reduction in the material. The purpose is to prevent the heat exchanger from being stored away, and to obtain a small, highly efficient, and low-cost heat exchanger.

In order to achieve this object, the present invention includes a secondary heat exchanger having inner and outer fins via a header on the downstream side of a combustion cylinder provided with a burner at one end, and extends into the secondary heat exchanger. In addition, a part of the internal fins on the upstream side of the secondary heat exchanger is removed, and one end is fixed to the header side plate by a mating process.

With this configuration, by reducing the combustion gas side heat transfer area on the upstream side of the secondary heat exchanger, gas side heat transfer on the upstream side of the secondary heat exchanger is suppressed, and temperature decreases. In other words, the temperature of the biting part can be prevented from rising and maintained within, for example, 300°C, thereby preventing the biting part from being damaged. Further, the action of the diffuser promotes turbulence within the secondary heat exchanger, thereby improving thermal efficiency.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 6.

In the figure, 1 is a burner integrally constructed with a combustion fan, 2 is a cylindrical combustion tube whose one end is connected to the burner, and 3 is a header which is connected to the opening at the other end of the combustion tube 2 and connected to a header side plate 4. The lid 5 is fixed. A secondary heat exchanger 6 is located parallel to the upper part of the combustion tube 2 and communicated with the header 3, and has a plurality of internal fins 7 formed from an extruded aluminum section 8 in the combustion gas flow direction. There is. An external fin 9 formed by wrapping an aluminum plate or the like is fixed to the outer periphery of the extruded shape member 8 by furnace brazing or the like of aluminum. At one end of the secondary heat exchanger 6, a part of the internal fin 7 is removed, and the outer periphery thereof forms a stepped part, which fits into a hole provided in the header side plate 4 to form a catch part 10. It is connected to the header 3 and fixed. The other end engages with the exhaust part 11 and the exhaust port 12
It is connected to. Reference numeral 13 denotes a combustion gas diffuser inserted into the secondary heat exchanger 6, and has a plurality of semicircular cut-and-raised portions 14 that alternately change the cut-and-raised direction. Reference numeral 15 is a blower disposed on the downstream side of the combustion tube 2, and reference numeral 16 is a convection blower, and a motor 17 is connected to one end thereof. A constant oil level device 18 supplies oil to the burner 1 via an electromagnetic pump 19. 19 is a flame formed in the combustion tube 2, and 20 is an outer casing.

In the above configuration, fuel is supplied into the burner 1 by driving the combustion fan and electromagnetic pump 19 in the burner 1, and is ignited by an ignition means (not shown) to form a combustion flame 19 and start combustion. sustained. High-temperature combustion gas generated in the combustion tube 2 is guided to the secondary heat exchanger 6 via the header 3, and then to the exhaust section 10.
The air is discharged to the outside air through the exhaust port 12. During this process, when the convection blower 16 is started by a thermostat (not shown) installed in a part of the equipment,
The high temperature combustion gas generated within the combustion tube 2 exchanges primary heat with the air passing through the outer surfaces of the combustion tube 2 and the header 3. During this process, the high-temperature combustion gas whose temperature has dropped to 600 to 700°C is led into the secondary heat exchanger 6. At this time, the heat transfer on the gas side on the upstream side of the secondary heat exchanger 6 is suppressed, and the high-speed air flow that absorbs heat from the internal fins 7 and passes through the outer periphery of the external fins 9 and the extruded section 8 and the secondary heat Replace it and the combustion gas temperature will be 150~
The temperature drops to a drastic 200℃ and is discharged to the outside air through the exhaust port.

In this embodiment, a means is shown in which the secondary heat exchanger 6 is made of an extruded aluminum material, but other methods include a case in which it is made of aluminum die-cast and can be attached to the header 3, or a flange part is provided and fixed. In any case, the idea of the present invention is effective in increasing the high-temperature strength of the bonded portion.

In this embodiment, by removing a part of the internal fins on the upstream side of the secondary heat exchanger 6 by machining or the like,
By reducing the heat transfer area on the upstream side and suppressing combustion gas turbulence, gas side heat transfer on the upstream side is suppressed, and an increase in the secondary heat exchange temperature on the upstream side is suppressed. As a result, as shown in Fig. 6, the temperature of the joint part of the secondary heat exchanger 6 can be maintained at a low temperature (for example, below 300°C), reducing the stress drop in the aluminum extruded section and preventing the joint part from being damaged. It is possible to prevent this from happening.

Furthermore, even if the removal dimension L on the upstream side of the secondary heat exchanger is increased, as shown in Figure 6, the degree of decrease in thermal efficiency is relatively small, and it is possible to maintain high efficiency and reduce the temperature at the interlocking part. It is something to do.

Furthermore, by suppressing the rise in the temperature of the upstream part of the secondary heat exchanger and reducing the temperature change in the longitudinal direction of the secondary heat exchanger 6, uniformity of the hot air blowing temperature is promoted and comfortable heating is achieved. Can be done.

In addition, by configuring the secondary heat exchanger 6 with an extruded aluminum profile, a large number of internal fins 7 can be provided to ensure a sufficient heat transfer area on the gas side, and at the same time, the wall thickness can be made thinner, resulting in a smaller size. to improve thermal efficiency (e.g.
93%) can be achieved.

Furthermore, compared to die-casting, heat exchangers made of extruded shapes can be manufactured using simpler molds, and their thinner construction requires relatively less material, resulting in lower manufacturing costs. By changing the cutting length of the material, it is possible to arbitrarily set the thermal efficiency and the capacity of the heat exchanger.

As is clear from the above description, the heat exchanger of the present invention is provided with a secondary heat exchanger having internal and external fins via a header on the downstream side of the combustion cylinder, and the inflow side of the secondary heat exchanger is connected to the header. The following effects can be achieved by clamping and fixing, removing a part of the internal fins on the inflow side to suppress heat transfer on the gas side, and providing a diffuser in the secondary heat exchanger. .

(1) It suppresses the temperature rise of the gripping part, provides stable gripping strength even under the harsh thermal cycles of hot air heaters, prevents the gripping part from being damaged, and extends its lifespan. A reliable seal can be ensured across the board.

(2) It is possible to equalize the temperature of the secondary heat exchanger and improve the uniformity of the hot air blowing temperature.

(3) By removing part of the internal fins, the heat transfer area is slightly reduced, which is disadvantageous for improving thermal efficiency, but by providing a diffuser, thermal efficiency can be ensured.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional heat exchanger, FIG. 2 is a perspective view of the main part of FIG. 1, FIG. 3 is a sectional view showing an embodiment of the heat exchanger of the present invention, and FIG. A side view of the secondary heat exchanger of the same heat exchanger, Fig. 4b is a cross-sectional front view of the main part of the secondary heat exchanger, and Fig. 5a is a plan view of the diffuser of the secondary heat exchanger. , FIG. 5b is a front view of the same diffuser, and FIG. 6 is a characteristic diagram showing the correlation between the removal dimension, the bite part temperature, and the thermal efficiency. 1... Burner, 2... Combustion tube, 3... Header,
4... Header side plate, 6... Secondary heat exchanger, 7...
Internal fin, 8... Extruded section, 9... External fin, 10... Biting portion, 13... Spreader, 14...
Cut and raise part.

Claims (1)

[Claims] 1. Combustion gas is introduced into a secondary heat exchanger having internal and external fins from a combustion cylinder equipped with a burner at one end through a header, and a diffuser is provided in the secondary heat exchanger to reduce the secondary heat. A heat exchanger in which a part of the internal fins on the upstream side of the exchanger is removed, and the secondary heat exchanger and header are fixed by interlocking processing.