JPH0427450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a heat exchange device using a heat pipe (hereinafter abbreviated as HP), which can be suitably used in hot air heaters and the like.

"Prior Art" As a heat exchange device for a hot air heater, as shown in FIG.
The heated air L is transferred to the heat exchanger tube 61 outside the heat exchanger tube 61.
Conventionally, a method in which the flow is perpendicular to the flow direction has been widely used.

Hot air heaters are required to blow hot air with as uniform a flow rate and temperature as possible into the room from a hot air outlet with a width of 40 to 60 cm, using a hot air blowing fan 65. In addition, the heat exchanger tube 61 is made to reciprocate in a meandering manner in two to three passes to make the temperature distribution of the hot air uniform.

However, with this method, the required heat transfer area is large, and the overall heat transfer coefficient is 20 to 30 kcal/m ² /
h/℃, and as a result, as long as this method is used, the miniaturization of the equipment is reaching its limit, and
There were problems such as a large temperature distribution in the width direction at the hot air outlet immediately downstream of the fan 65.

``Problems to be Solved by the Invention'' The present invention has been developed in view of the fact that conventional heat exchange devices for hot air heaters have limitations in miniaturization and that there is temperature unevenness at the hot air outlet. The purpose is to provide a new heat exchange device that solves the above problems.

"Structure of the Invention" The heat exchange device of the present invention has a heating fluid flow path including:
A heat receiving part of the HP, a radiator provided downstream adjacent to the heat receiving part so as to be ventilable, and another heat receiving part of the HP provided downstream of the radiant, or another heat receiving part of the HP provided downstream of the radiant.
The heat receiving part of the HP is arranged in the flow path of the heated fluid, and the heat radiating part of the HP is arranged in the flow path of the heated fluid.

Since HP is used in the present invention, there is no temperature unevenness in the longitudinal direction of the heat radiation part of the HP, and therefore there is no temperature distribution in the width direction at the hot air outlet.

Further, in the HP heat receiving section, a radiator that is provided so as to be ventilated is disposed downstream close to the heat receiving section provided on the upstream side of the heating fluid flow path, that is, on the high temperature side.

Therefore, this heat-receiving part receives heat from the high-temperature heating fluid flowing around it, e.g.
Not only is the radiant heated by convective heat transfer with an extremely large temperature difference of 1500°C, but the radiant is heated and becomes incandescent by the convective heat transfer between the heating fluid and the radiant, and this incandescent radiant Strong radiation is effectively irradiated onto the upstream heat receiving section based on the large temperature difference mentioned above.

Thus, the upstream heat receiving section is heated by both convective heat transfer and radiation heat transfer, and the heat transfer coefficient between the heating fluid containing high temperature flame and the above HP heat receiving section is:
It reaches 100-200 kcal/m ² /h/℃.

The heated fluid that passed through the radiator is still at 700-1000℃
It is then guided to another HP heat receiving section, particularly another HP heat receiving section having fins on its outer surface, where the heat is sufficiently absorbed. Here, the other HP heat receiving section may be a heat receiving section of another HP, or may be another HP heat receiving section of the same HP whose heat receiving section was previously arranged on the upstream side. Due to this high heat transfer coefficient, miniaturization is achieved.

Therefore, when generating hot air by exchanging heat from high-temperature combustion gas through HP, special consideration must be given to the heat receiving part in order to secure heat radiation of, for example, 3000 kcal/h. Diameter 34mm
However, according to the present invention, only one or two HPs with a diameter of 34 mm are required, which is advantageous in terms of cost and space. There will be great benefits.

In a preferred embodiment of the present invention, the heat receiving section provided upstream close to the radiator is a bear tube or a loaf inch tube with a fin height of 3 mm or less, particularly a bear tube, and the heat receiving section provided downstream of the radiator is a bear tube. The finch tube has a higher fin height than the bear tube or the loaf tube. If the upstream heat receiving section is a tube with a high fin height, the fins are likely to be thermally damaged by high temperatures. If the heat receiving section on the downstream side is a tube with a lower fin height than the above, the heat transfer area will be insufficient and it will be difficult to absorb sufficient heat.

On the other hand, it is desirable to attach fins to the heat dissipation part of the HP to promote heat dissipation and to maintain the temperature of the working fluid inside the HP within a predetermined temperature range.

The radiator is preferably made of a heat-resistant material, such as a ceramic material such as silicon carbide, silicon nitride, aluminum nitride, etc., so that it can generate effective radiant heat at high temperatures. As for the shape, it is preferable to use a shape that has its own air permeability, such as a honeycomb, cloth, or three-dimensional net, but it is recommended to use small balls, thin strips, thin rods, etc. that do not have air permeability on their own, and to space them at appropriate intervals. The heating fluid may be permeable through the radiator layer, such as by arranging the radiator layer in a radiator layer.

Regarding HP, when using it in a hot air heater,
The tube material is preferably stainless steel, copper, aluminum, etc., and the working medium is preferably water, fluorocarbon, dowsome, naphthalene, etc.

In the present invention, the heating fluid is a high-temperature combustion gas generated by burning gaseous fuel such as city gas, propane gas, natural gas, or liquid fuel such as kerosene, particularly a high-temperature gas of 1500 to 1700°C. of combustion gas is preferred. As the combustion means, a diffusion combustion burner or a premix burner can be used.
In this case, the distance between the upstream edge of the heat receiving part of the upstream HP and the fuel gas discharge port of the combustion means (for example, the tip of the burner or the downstream surface of the burner plate) is 50 to 150 mm for a diffusion combustion type burner, and 100 mm or less for a premix type burner. Therefore, it is preferable that this contributes to the miniaturization of the device of the present invention. Note that even if this distance is shortened in this way, the oxidizing function of the incandescent radiator will suppress the generation of incomplete combustion components such as CO.

In the present invention, preferably one or two HPs having an upstream heat receiving section are arranged, and another HP having a downstream heat receiving section is arranged.
Preferably one or two HPs are also arranged. Note that although the upstream heat receiving section is exposed to a considerably high temperature, it is cooled by the heated fluid such as air flowing through the heat radiating section, so that thermal damage is prevented.

"Embodiment" In the heat exchange device according to the embodiment of the present invention shown in FIGS. 1 and 2, the casing 9 separates a flow path for combustion gas H, which is a heating fluid, and a flow path for air L, which is a fluid to be heated. are doing. A premixture P, which is a mixture of combustion air and fuel gas at a predetermined ratio, is guided to a planar burner plate 4, which is a combustion means. This burner plate 4 has a large number of flame holes passing through it, and the premixture P that has passed through the flame holes forms a planar flame on the downstream side of the burner plate 4, and becomes combustion gas H.

Burner plate 4 viewed in the direction of flow of combustion gas H
There are two heat receiving parts 1 of the 1st HP 1 downstream near the
a is arranged, and a radiator 3 made of ceramic honeycomb is arranged downstream close to the heat receiving part 1a. In addition, there are two 2nd HP downstream near the radiator 3.
2 heat receiving parts 2a are arranged. In this example, the 1st HP
The heat receiving part 1a of No. 1 is a bare tube without fins,
The heat receiving part 2a of the 2HP2 is a finch tube having fins 7. The heat receiving section 1a, the radiator 3, and the heat receiving section 2a are all arranged perpendicular to the flow of the combustion gas H.

In addition, in the part downstream from the downstream surface of the burner plate 4 and through which the fairly high temperature heating fluid H flows,
A heat insulating lining 10 is provided.

The first HP1 and the second HP2 each extend to the flow path of the air L, are arranged perpendicular to the flow of the air L, and function as a heat radiating part 1b and a heat radiating part 2b, respectively. The heat radiation part 1b and the heat radiation part 2b each have fins 7 and have a required heat radiation area. Further, in this embodiment, the heat radiating part 2b, the heat radiating part 1b, and the fan 5 are provided in this order along the flow of the air L. For example, the heat radiating part 1b, the heat radiating part 2b, the fan 5 They can also be provided in this order.

It is preferable for a hot-air heater that the working medium of the first HP1 is an organic heat transfer oil such as Dowsum or naphthalene, and the working medium of the second HP2 is water, but depending on the conditions, the working medium of the second HP2 may also be an organic heat transfer medium. It can also be heat transfer oil or naphthalene. No.
When naphthalene is used as the working medium of 2HP2, the height of the fins of the heat dissipation section 2b should not be too high in order to prevent the working medium from coagulating.

In another embodiment shown in FIG. 3, the heat receiving section of the HP 6 is divided into a high temperature side heat receiving section 6c and a low temperature side heat receiving section 6d, with the heat receiving section 6c being a bear tube and the heat receiving section 6d being a finch tube. A heat receiving part 6c is placed downstream of the burner plate 4, and a radiator 3 made of ceramic honeycomb is placed close to and downstream of the heat receiving part 6c at a position where radiation irradiates the heat receiving part 6c, and the combustion gas diverted by the casing 9 receives heat. It is arranged so as to heat the portion 6d. 6b is a heat radiation part.

According to this embodiment, the number of HPs can be reduced compared to the embodiment shown in FIG. 1, for example, only one HP in total, resulting in a more compact heat exchange device.

In the embodiment shown in FIG. 3, it is also possible to divert the heating fluid that has passed through the heat receiving section 6d once again to provide heat to yet another heat receiving section of the HP 6.

In these examples, a sufficient effect can be obtained even if the HP is installed horizontally, but if the HP is tilted by 10 degrees or less, preferably about 6 degrees, so that the heat receiving part is lowered, the thermosiphon principle can be applied. Yes, HP
The amount of heat transported is further increased and a more compact device is formed.

In the example shown in FIG. 4, heat receiving parts 1a made of loaf inch tubes having fins 8 with a height of 2 mm are arranged in a staggered manner in multiple stages, and from the radiator 3 to the burner plate 4.
The structure is substantially the same as the example shown in FIG. 1, except that the heat receiving portions 2a are arranged in a staggered manner in multiple stages to block as much radiation as possible.

In the example shown in FIG. 5, a plurality of radiators 3 made of ceramic honeycomb are arranged inclined toward the axial direction of a heat receiving part 6c made of a loaf inch tube having fins 8 with a height of 2 mm. The embodiment is substantially the same as the embodiment shown in FIG. 3, except that the radiation from the heat receiving section 6c is made to enter the heat receiving part 6c more effectively.

In this way, the heat receiving portions 1a to 6c may be formed into loaf inch tubes with a fin height of 3 mm or less as long as the fins do not overheat or the working medium is overheated.

In addition, in the examples shown in Figures 1, 3, and 5, HP
1, 2, and 6 can each be one or more,
Needless to say, in the case of a plurality of sheets, they may be arranged horizontally in the same row or in a staggered arrangement in multiple rows.

"Function" In the present invention, the high temperature heating fluid flow path has HP
A heat-receiving part, a ventilated radiator adjacent to the downstream side, and a second heat-receiving part downstream of the heat-receiving part are arranged.Radiation heat transfer mainly acts on the heat-receiving part on the upstream side, and the high-temperature fluid A high heat transfer coefficient from HP to HP is achieved. Of course, convective heat transfer is also performed between the high temperature fluid and each of the above-mentioned heat receiving parts.

Further, by arranging the radiator in this manner, most of the heat radiation from the radiator to the combustion means such as the burner plate is blocked by the upstream heat receiving section, thereby preventing overheating of the combustion burner, backfire, etc. For this purpose, when the upstream HP consists of a plurality of HPs, a staggered arrangement is preferable. In the downstream heat receiving section, the temperature of the heated fluid decreases and there is less risk of damage to the fins, so it is possible to further promote heat transfer by attaching fins to the outer surface.

As described above, the heat flowing into the upstream and downstream heat receiving sections is very effectively transferred to the heat radiating section by the action of HP. This heat increases the temperature of the tube in the heat dissipation section of the HP, but as a characteristic of the HP,
There is almost no temperature variation in the longitudinal direction of the HP. Therefore, uniform hot air required for a hot air heater can be obtained.

Furthermore, in the HP, heat is transferred within the tube through phase changes (evaporation, condensation) of the working medium contained within the tube, so heat transfer within the HP is extremely effective. Therefore, heat transfer from the heating fluid to the heated fluid is substantially limited by heat transfer from the heating fluid to the outer wall of the HP heat receiver and from the HP heat sink to the heated fluid.

As for the heat dissipation part, it is possible to provide dense fins as long as pressure drop is allowed, so even if the heat transfer coefficient is relatively small, it is possible to obtain a large heat flux per HP tube outer surface area.

The problem is the heat receiving part, but according to the present invention, the heat receiving part on the upstream side, that is, on the highest temperature side and closest to the burner plate, consists of a bear tube or loaf inch tube and is close to the high temperature flame.
800 to 1500 between the high temperature heating fluid and the outer wall of the heat receiving part
A temperature difference of ℃ is given, and the radiator has a temperature difference of 900~
A high temperature fluid of 1200℃ flows in and makes the radiator incandescent,
Strong radiation is irradiated from the incandescent radiator to the upstream heat receiving part, and the heat transfer coefficient between the heating fluid and the heat receiving part reaches 100 to 200 kcal/m ² /h/℃,
In addition, the heated fluid, whose temperature has decreased to 700 to 1000℃ after passing through the radiator, is guided to the downstream side heat receiving part with fins on the outer surface, where it absorbs heat mainly through convection heat transfer, so it can effectively generate heat. They can be replaced, and the number of HPs in the heat receiving section can be reduced to 1/3 to 1/6 compared to a case not using the configuration of the present invention.

"Effects of the Invention" As explained above, according to the present invention, the heat exchange device can be downsized, so the hot air heater can be downsized,
Not only can it be made thinner, but the temperature of the hot air blown out can be made more uniform.

Note that the device of the present invention is not only a hot air heater, but also a hot air heater.
It can also be used to heat cooking oil, bathtubs, etc.

[Brief explanation of drawings]

Fig. 1 is a sectional view of one embodiment of the device of the present invention;
The figure is a sectional view taken along the - line in Fig. 1, Figs. 3, 4, and 5 are sectional views of different embodiments of the device of the present invention, and Fig. 6 is a sectional view of a conventional hot air heater. FIG. 2 is a cross-sectional view of the dexterous heat exchange device. 1, 2, 6...Heat pipe, 1a, 2a, 6
c, 6d... Heat receiving section, 1b, 2b, 6b... Heat radiating section, 3... Radiator, 7, 8... Fin.

Claims (1)

[Scope of Claims] 1. A heating fluid flow path includes a heat receiving part of a heat pipe, a radiator provided downstream of the heat receiving part so as to be ventilable, and the heat pipe provided downstream of the radiant. or a heat receiving part of another heat pipe, and a heat radiating part of the heat pipe whose heat receiving part is arranged in the flow path of the heated fluid is arranged in the flow path of the heated fluid. Heat exchange equipment. 2. The heat receiving part provided upstream close to the radiator is a bear tube or a loaf inch tube with a fin height of 3 mm or less, and the heat receiving part provided downstream of the radiator is arranged in a loaf inch tube with a fin height smaller than the bear tube or loaf inch tube. The heat exchange device according to claim 1, which is a finch tube having a high height.