JPS5947216B2 - Heat storage device for heater - Google Patents

Description

[Detailed description of the invention] The present invention relates to a heat storage device for a heater.

Conventionally known heat storage devices for heaters only retain heat by covering the heat storage body with a heat insulating material such as calcium silicate, felt, glass wool, ceramic fiber, etc., so the thickness of the heat insulating layer must be increased. There are problems with practicality because the heat retention performance decreases and if the layer thickness increases, the overall volume increases. In order to increase the heat retention ability and extend the heater operating time to make it more practical, it can be proposed to use a) a heat storage body with a high heat storage density, or (a) a heat insulating material with a low thermal conductivity. In the case of (a), expensive materials such as lithium fluoride, hydrogen fluoride, lithium hydroxide, etc. must be used for the heat storage body, and it is not very practical in terms of safety. Since the thermal conductivity of the material is unique to each substance, there is a disadvantage that a new insulation material with a low thermal conductivity must be developed. Therefore, the present inventors investigated the structure of heat insulating materials in detail, and found that heat insulating materials are either porous solids containing many pores, or fibrous cloth in which countless fine fibers are entangled. It was discovered that the insulating effect of the air contained in the material, that is, the fact that air has low thermal conductivity, is utilized. Furthermore, the idea was that a gas with low thermal conductivity could be included in the heat insulating material instead of air.

The present invention was developed based on the above-mentioned findings and ideas, and specifically, the present invention stores heat in a heat storage body, surrounds the heat storage body with a heat insulating layer filled with a heat insulating material to keep it warm, and uses this heat as a heat source. In a heat storage device for a heater, the above-mentioned heat insulating layer has a double structure, and the inner heat insulating layer contains carbon dioxide, which does not thermally decompose even at high temperatures and has a lower thermal conductivity than air, and the outer heat insulating layer contains carbon dioxide gas, which does not thermally decompose even at high temperatures and has a lower thermal conductivity than air. The object of the present invention is to provide a heat storage device for a heater, characterized in that Freon gas, which has a low thermal conductivity, is sealed instead of air, thereby lowering the thermal conductivity of the heat insulating layer and improving the heat retention property.

The details will be explained below based on the drawings.

In the figure, 1 is a heat storage for a heater, 2 is a Sirotskov fan that blows out hot air for heating, and 3 is a motor for rotating the Sirotskov fan.The heater heat storage 1j stores heat in a heat storage body 4 and is filled with a heat insulating material 5. The heat storage body 4 is surrounded by a heat insulating layer 6 to keep it warm, and this heat is used as a heat source.

Materials such as magnesia, alumina, lithium nitrate, hydroxide (hysodium, magnesium fluoride, etc.) can be used for the heat storage body 4.To store heat, connect the heating wire T shown in the figure to an external power source and store heat by electric heat. Alternatively, although not shown, heat may be exchanged and stored using other heat sources, such as cooling water or exhaust gas from an automobile engine. In the figure, 8 is a gas filling port, 9 is an air discharge port, and 10 is a gas filling port. is a gas cylinder, 11
12 is a vacuum pump, 12 is a heating air intake, 13 is an opening/closing shutter, and 14 is a heating air passage. By the way, the present invention is characterized in that a gas having a lower thermal conductivity than air is filled in the heat insulating layer 6 of a heat storage device having such a structure instead of air, thereby lowering the apparent thermal conductivity of the heat insulating layer 6 and improving heat retention characteristics. has.

Freon 12 and Freon 21 are gases with low thermal conductivity.
Freons, carbon dioxide gas, etc. can be used, and in order to seal in such a gas, the air in the heat insulating layer 6 can be removed using the vacuum pump 11, and then the desired gas can be filled in from the gas pump 10. In the heater heat storage device 1 as shown in Figs. 1 and 2, length l = 30cTn width W = 20
Heat storage body 4 with external dimensions cTn height h = 15cTn
The heat retention characteristics are shown in FIG. 4 when lithium nitrate (LlNO3) is used as the heat insulating layer and ceramic fiber having a thermal conductivity of 0.05 Kcal/11'C and a thickness of 2C7rL is used as the heat insulating layer. According to Figure 4, the temperature was initially 400℃.
If the temperature was heated to 150℃, the temperature would drop to 12℃.
It is possible to keep warm for hours (when the outside temperature is -10°C). However, in reality, when used as a heater under these conditions, the heater operation time is extremely short, 10 to 15 minutes, because the amount of residual heat is small. However, according to the present invention, the heat insulating layer 6
Instead of air, a gas with a lower thermal conductivity than air is filled in, and the conductivity of the heat insulating layer 6 is reduced to the initial air-filled state (0.05Kc).
a1/Mh℃) (in the case of Freon gas filled, it varies depending on the material such as the porosity of the insulation material 5 and the condition of the fibers, but it is approximately 0.015 to 0.03Kca1/Mh'C)
(the conductivity can be lowered to 100%), resulting in heat retention characteristics as shown in FIG. That is, it is possible to maintain the temperature for about 20 to 40 hours until the temperature drops from the initial 400°C to 150°C. In this way, thermal conductivity can be lowered and heat retention properties can be improved. Next, FIG. 3 will be explained. This embodiment is particularly intended for a high-temperature heat storage device 1a, and the heat insulating layer has a double structure. The inner heat insulating layer 6a is filled with a gas that does not thermally decompose even at high temperatures and has a lower thermal conductivity than air, such as carbon dioxide, and the outer heat insulating layer 6b is filled with a gas that does not thermally decompose even at high temperatures and has a lower thermal conductivity than air, such as Freon gas. It is to be enclosed. In this way, in addition to the functions and effects of the present invention explained in FIGS. 1, 2, 4, and 5, the heat storage temperature can be increased to a high temperature (250
℃ or higher), the carbon dioxide gas sealed in the inner heat insulating layer 6a prevents thermal decomposition of the Freon gas sealed in the outer heat insulating layer 6b, lowering the thermal conductivity of the heat insulating layers 6a and 6b, and improving heat retention properties. It is something that can be done. Regarding the gas filling described above, it is difficult to seal the container of the heat storage device 1, Ia even if the gas filling pressure is higher or lower than atmospheric pressure, so the gas filling pressure is set to be approximately the same as atmospheric pressure. , or in a state in which gas is included in the fibers.

As explained above, according to the present invention, the heat retention properties are significantly improved by lowering the thermal conductivity of the heat insulating layer, so the thickness of the heat insulating layer can be made extremely thin compared to conventional heat storage devices, and the entire heat storage device can be made smaller. Moreover, even if a relatively inexpensive heat storage material with a low heat storage density is used for the heat storage element, the heater operation time can be extended, and if a heat insulating layer of the same thickness as before is used, The heat storage capacity of the heater according to the present invention is greatly improved compared to conventional ones. It is highly practical, as it can be used for heating after the engine is stopped or when starting the next morning, as well as other heaters.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the entire heater heat storage device according to the present invention, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 3 is a heater heat storage device according to another embodiment. A cross-sectional view similar to Fig. 2, Fig. 4 is a graph showing the heat retention characteristics of a heat storage device when lithium nitrate is used as the heat storage medium and ceramic fiber is used as the heat insulating material, and Fig. 5 is a graph showing the difference in thermal conductivity. It is a graph showing the heat retention characteristics of the heat storage device according to In the figure, 1, Ia... Regenerator for converter, 4, 4a
... Heat storage body, 5 ... Heat insulation material, 6, 6a
, 6b... Heat insulation layer, T, 7a... Heating wire.

Claims (1)

[Scope of Claims] 1. In a heat storage device for a heater that stores heat in a heat storage body, surrounds the heat storage body with a heat insulation layer filled with a heat insulating material, and uses this heat as a heat source, the heat storage body has a double layer structure. The inner insulation layer is filled with carbon dioxide, which does not thermally decompose even at high temperatures and has a lower thermal conductivity than air, and the outer insulation layer is also filled with Freon gas, which has a lower thermal conductivity than air. A heat storage device for a heater, characterized by lowering the thermal conductivity of the layer and improving heat retention properties. 2. The heat storage device for a heater according to claim 1, wherein the gas filling pressure is made to be approximately the same as atmospheric pressure.