In last installment we mainly introduced the composition and structure of lightweight insulating brick materials. In this installment, we will introduce porosity and characteristics of pores of lightweight insulating bricks.
(2)Porosity and characteristic of pores of lightweight insulating bricks
As the porosity increases, the thermal conductivity rise up straight. At this point, lightweight insulation bricks performance is particularly outstanding. However, for the same porosity, the smaller the size of the pores and the more uniform the distribution, the smaller the thermal conductivity. When the pore size is small to a certain extent, the air in the pore is completely adsorbed by the pore wall, so that the inside of the pore is close to the vacuum state, and the thermal conductivity is minimized. When the pore size is increased to a certain extent, the heat radiation between the inner wall of the pore and the convective heat exchange of the air in the pore increase, and the thermal conductivity increases. According to relevant literature, the thermal radiation in small pores is very small. When the pores are large, especially the long pores along the radiation direction, the heat radiation efficiency can be increased. Sometimes, the thermal conductivity of the product with pores can be higher than that of the dense products. The thermal conductivity of the closed pores is lower than that of the open pores.
In this installment we mainly introduced the porosity and characteristics of pores of light weight insulation bricks. Hope this can bring help to furnace builders. Next week we will introduce density and temperature of light weight insulation bricks. Please stay tuned.
