JPS5814481A - Heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating element that emits far infrared rays and is used for heating for heating or drying.

It is well known from physics that black bodies at low temperatures emit far-infrared rays.

For example, a perfect black body at 100° C. emits far infrared rays of a continuous spectrum having a maximum wavelength of 7.76 μm at a rate of 0.1099 W/i into the space at absolute zero temperature. Similarly, a perfect black body at 10° C. emits far infrared rays having a maximum wavelength of 10.25 tt at a rate of o, 0665 W/cnIi. 80% of the radiant energy is contained between a wavelength 47) 0.76 times the maximum value and a wavelength 6.3 times the maximum value.

The above is the case of a completely black body, and actually existing heating elements generally have a lower emissivity than this and emit so-called gray radiation.

This emissivity varies depending on the material, but for far infrared rays, ceramic 1. Glass, marble, plaster, etc. have a completely black body of about 90~
It has an emissivity of approximately 93%, and it is also known that painted surfaces such as enamel paint have approximately the same emissivity.

The present invention makes use of these properties to create a heating element that directly sends energy in the form of radiation to a target object without heating the air around the heating element, and exhibits a large energy-saving effect in the field of drying or heating. The purpose is to provide.

Conventional hot air heaters and the like have the disadvantage that because they send out warm air to warm the entire room, this heat escapes to the outside through walls, windows, ceilings, etc. This required a considerable amount of calories for heating.

In addition, conventional radiant heating elements include electric stoves using nichrome wire, infrared lamps using tungsten wire lamps, and gas stoves using red-hot pottery, but all of them have limited area. Because it uses a small number of high-temperature radiators, there is a risk of fire or burns if the object to be heated is brought close, and conversely, the heating effect decreases rapidly if the object is moved away.

The present invention eliminates such drawbacks, and
The present invention provides a heating element that uses a radiator with a low temperature of around ℃, widens its area to form a surface heating element, and further prevents the movement of air near the radiating surface to reduce heat loss due to air convection. .

The present invention will be explained in detail below.

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. In FIGS. 1 and 2, 1 is a flat radiator, 2 is a heat insulating material, 3 is an outer casing, 4 is a fiber, and 5 is a heat source for warming the radiator 1. The radiator l has a large surface area,
It has a structure that allows its surface to be heated evenly. Generally, a metal plate is used, and the back side of the plate can be heated with electricity, gas, kerosene, hot water, hot air, etc., for example. In the example of FIG. 2, the radiator 1 is heated by a heat source 5 made of a hot water pipe. The surface that emits far-infrared rays is coated with a paint with high emissivity, such as enamel. Metal surfaces generally have extremely poor emissivity; for example, a well-polished copper plate emits only about 4% of that of a completely black body, but if you paint it with enamel, the emissivity increases by about 90%.

Also, even if you apply a heat-resistant rubber such as silicone rubber, the surface will be covered with dust! - Even if the powder is closely glued or the enamel is baked, the emissivity will be improved. The reason why metal is used as the base material is that metal has good thermal conductivity, so it is easy to make the surface temperature uniform.

The surface temperature of this radiator 10 is 4. ;, '6 o~300
It is kept at ℃. Now, if the temperature is...100°C, far infrared rays (heat rays) are emitted at a rate of about 660 W/- with an emissivity of 90% in a space where the ambient temperature is 10°C.

At 600°C, this becomes a rate of 5180 W/m'.

The heat insulating material 2 is used to prevent heat loss to the back surface (backward) when radiation is not directed toward the back surface but only toward the front surface. This heat insulating material 2 may be similar to the heat insulating material used for the walls of ordinary houses.

The outer casing 3 is an outer casing that supports the entire heating element, and the front is open to allow radiation to pass through.

The fibers 4 are thin like cotton and cover the top of the radiator 1, and prevent the flow of air around the radiator 1 due to convection or the like.

However, unless the density is too high, far infrared rays will be emitted through the gaps.

The fibers 4 can be made of a material that transmits far infrared rays, such as nylon (registered trade name), etc., to achieve good results, but if heat resistance is particularly required, in other words, if the surface temperature of the radiator 1 is 600°C. Glass fiber is suitable when the material is in a high position.

When glass fiber is used as the fiber 4, the glass fiber absorbs far infrared rays well, so if the fiber is vapor-deposited, most of the far infrared rays will be reflected on the surface of the fiber 40 and absorbed by the fiber 4. Far-infrared rays generated by the system are reduced, further increasing its effectiveness.

The effectiveness of the fibers 4 is highest when the radiation surface of the radiator l is horizontal and radiates downward.

This is because the high-temperature air heated on the surface of the radiator 1 tries to go upward, but its movement is blocked by the fibers 4 and the surface of the radiator 1, and it stays near the surface of the radiator 1, maintaining a high temperature. Therefore, cooling of the surface of the radiator 1 by air is prevented.

On the other hand, when the radiation surface of the radiator 1 is horizontal and faces upward, the effect of the fibers 4 is the least.

Even in this case, if the fibers are densely packed, air convection will be hindered to some extent, and some effect will be exerted.

When the surface of the radiator 1 is vertical, the effect of the fibers 4 is intermediate between the above two examples.

FIG. 6 is a sectional view showing another embodiment of the present invention.

In FIG. 3, 6 is a film that transmits radiation in the far infrared region.

As mentioned above, the radiator radiates far infrared rays in the range from 100°C to 300°C and several Qm to several 10 μm.

The film 6 is a film that is highly transparent to radiation in this band.

Some of these films can be seen inside the plastic film.

For example, taking a polyethylene film as an example, its infrared ray pass band is as shown in FIG.

As you can see in this figure, most of the far infrared rays pass through. However, since airflow can be blocked, losses due to convection can be further reduced by attaching such a film to the outside of the fibers 4 as shown in FIG.

The air inside the fibers 4 covered with the film 6 hardly causes convection due to the air resistance of the fibers 4, and acts effectively as a heat insulating material. Moreover, since far-infrared rays are radiated through the air in the gaps between the fibers 4 and the entire film 6, the heating effect of the radiation can be sufficiently exerted.

Such an effect of the film 6 is particularly effective when the radiator 1 is horizontal and emits radiation upward. In such a case, the air warmed on the surface of the radiator 1 will rise upward through the fibers 4 when the film 6 is not present, causing air convection and cooling the radiator 1. This is because the film 6 can prevent this convection.

For the same reason, it is also effective when the radiator 1 is vertical.

The film 6 alone is effective because it can prevent air convection to some extent even without the fibers 4, but if both the fibers 4 and the film 6 are present, the air appears to be subdivided and confined within a small space. Therefore, it is possible to more effectively cool the radiator 1 by heat transfer, or in other words, prevent loss. This effect is particularly effective when the radiator 1 is used for drying purposes.

When drying, it is common to speed up the drying process by forcefully blowing air to release the evaporated water vapor and other vapors to the outside. 6 has a large insulation effect.

As is well known, the amount of heat transferred from a plane to the surrounding air by convection is proportional to the product of heat transfer coefficient, surface area, time, and temperature difference.

Various experimental formulas have been given for the heat transfer coefficient by several scholars, but when we calculate the heat transfer coefficient due to convection from a flat plate surface in the case of forced convection using the Juges formula, we find that it is a smooth surface. Assuming a wind speed of 4 m, it is approximately 18 KSIl/-h°C.

If fiber 4'@film 4 is also absent': > 9, the thermoelectricity carried away by convection from the surface of radiator 1 by the wind will reduce the surface temperature of radiator 10 to 150i: and the temperature of the wind to 30°C. As a radiator 1-1, 1 hour is 1.8
X (150°C-3o°C) = 2160-. Radiation, radiator 1 when the surface of the body is 150 degrees Celsius
The amount of heat radiated to the object at 30° C. is 1206 il per hour, assuming the emissivity is 90%.

In other words, in order to obtain -radiant heat at 1206, (12) 0.6+
216C)) K- of heat is required,
Heat from convection exceeds heat from radiation. Although the above calculations are rough estimates, they are sufficient to understand the magnitude of loss due to convection.

On the other hand, when the fibers 4 and the film 6 are present, the heat carried away by the wind is greatly reduced due to the above-mentioned insulating effect of both.

The thermal conductivity of the air layer created by the fibers 4 and the film 6 varies depending on the density of the fibers 4, etc., but per 1°C temperature difference,
The amount of heat that flows through the fibers 4 and the Z illumination per hour is estimated to be 3 to 5'Kd.

Therefore, the greater the heat transfer from the surface by the wind, the lower the surface of the film 1 is cooled, and the amount of heat removed from the surface is smaller than when the surface of the high temperature radiator 1 is directly exposed to the wind.

When the surface temperature of the radiator 1 is 150°C, the surface temperature of the film 6 is around 50 to 60°C in the above example when the wind speed is 4 m, and the heat loss due to the wind is about 360 to 540 Kd. Compared to 2160Kadl, it is significantly reduced.

Due to the action of the fibers 4 and the film 6, the amount of heat required to obtain the same radiation is approximately halved, and this method is found to be particularly effective when drying under forced ventilation. Ru.

Suitable materials for the film 6 other than polyethylene include polyamides, such as nylons (registered trademark L polypropylene) such as nylon 11 and nylon 610. Although it absorbs more far-infrared rays, it has a high heat resistance, making it very suitable as a material for the film 6, and its infrared transmittance is the best among the various films mentioned above.

As mentioned above, the one-plane radiator 1 is heated to 80°C to 300°C.
By heating the heating element to a certain temperature and attaching the fiber 4 to the front surface thereof, a heating element that efficiently radiates heat rays can be obtained.

Furthermore, a film 6 that transmits far infrared and rays is placed on the outside of the fiber 4.
The effect can be further enhanced by covering it with '.

These inventions bring about the following various effects.

To heat with air, the temperature of the air must be higher than the temperature required by the object to be heated, but when heating by radiation, the temperature of the air must be lower than the temperature of the object to be heated. Therefore, the heat loss can be reduced accordingly.

It has good thermal efficiency because it directly heats the object to be heated without heating the surrounding air. Also, since it is heated using radiation (a type of radio waves), there is no delay in the heating effect. Even in places where cold wind blows like in winter 5↓, the fiber 4 or the combination of fiber 4 and film 6 prevents the radiator from cooling, so a heating effect can be expected.

It can effectively heat buildings with high ceilings, such as large warehouses and open-air rooms.

4% fiber or fiber 4. and film, 6 Since the loss due to convection is reduced, fewer calories from the heat source are required to obtain the required amount of radiation heat. Therefore, it is particularly effective in dry air machines that use forced ventilation.

As mentioned above, the present invention has a simple structure and is energy saving.
゜Crab, ka. ,. Ei□. Yes, the economic effects are significant.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a cross-sectional view thereof, Fig. 3 is a cross-sectional view showing another embodiment of the present invention, and Fig. 4 is a perspective view of polyethylene in the far infrared region. It is a figure showing transmittance. 1...Radiator, 2...Insulating material, 4...Fiber, 5...
...Heat source, 6...Film. Patent applicant International Technology Development Co., Ltd. Al Wavelength (/l) Wave number (cnr)

Claims (3)

[Claims] (1) A heating element characterized by a radiator having at least one radiating surface, a means for warming the radiator, and a cotton-like fiber covering the radiating surface to prevent heat loss due to air convection. . (2) The heating element according to claim 1, wherein the radiator is made of a metal plate whose surface is covered with a material having a high emissivity. (3) The heating element according to claim 1, wherein a film that transmits far infrared rays is provided on the front surface of the radiation surface.