Ceramic fiber modules are widely used in various industrial kilns and furnaces due to their excellent thermal insulation properties. The insulation performance of ceramic fiber modules primarily depends on their heat transfer characteristics.
In nature, gases (with the exception of hydrogen) generally have low thermal conductivity. In a static state, gases exhibit low thermal conductivity and low heat capacity. The thermal conductivity of ceramic fiber is close to that of gases because it is composed of solid fibers intertwined with a high volume of pores, resulting in a porosity rate of up to 90%.
So, what factors influence the heat transfer in ceramic fiber modules?
01 Effect of Porosity
Thermal insulation materials have an optimal porosity and bulk density at various operating temperatures, within which the insulation performance is the best. Accordingly, ceramic fiber modules are classified into different grades based on their maximum service temperature. Their density is also adjusted within the range of 210–260 kg/m³ depending on the application.
02 Effect of Environment
The low thermal conductivity of ceramic fiber modules is based on the presence of common gases. However, they are not suitable for environments containing high-conductivity gases such as hydrogen or helium.
03 Effect of Bulk Density
For ceramic fiber products to maintain low thermal conductivity, the optimal density should be below 250 kg/m³, with a porosity higher than 90%.
04 Effect of Orientation
During the forming process of ceramic fiber blankets or boards, the length and width directions are the primary orientations. The thermal conductivity of the front surface is much lower than that of the side surface. Therefore, during installation, the back side of the fiber product should be placed against the furnace wall, with the front surface facing the high-temperature zone. The product should not be installed perpendicular to the furnace wall.
