Ceramic fiber modules are now widely used in various kilns and industrial furnaces. The realization of thermal insulation of ceramic fiber modules mainly depends on its heat transfer characteristics.
Then the gas with low thermal conductivity in nature (except hydrogen) is a substance with low thermal conductivity and low heat capacity in a static state. The thermal conductivity of ceramic fibers is basically close to that of gas. This is because ceramic fibers are interwoven with solid fibers, filled with gas, and have a porosity of 90%. What factors affect the heat transfer of materials such as ceramic fiber modules?
1. The effect of porosity
The thermal insulation material has a better porosity, that is, the volume density, at each use temperature, and the thermal insulation effect is the best in this range. Therefore, the ceramic fiber module is divided into several grades according to the use temperature, and the density is adjusted accordingly in the range of 210-260 according to the use situation.
2. The influence of atmosphere
The low thermal conductivity of the ceramic fiber module is based on most gases, but if there are high-heat gases such as hydrogen or helium in the environment, ceramic fiber products are not applicable.
3. The influence of bulk density
For ceramic fiber, to maintain a low thermal conductivity, the preferred density of ceramic fiber products is 250kg/m3 or less, and the porosity is above 90%.
4. The influence of directionality
In the forming process of ceramic fiber blanket or ceramic fiber board, the length and width direction of the area is the main direction. Moreover, the thermal conductivity of the front surface of the fiber product is much smaller than that of the side surface. Therefore, the back of the fiber product is close to the furnace wall during the application process, and the front surface is a high-temperature contact surface. The fiber product cannot be installed perpendicular to the furnace wall.
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