Factors affecting heat insulation of lightweight refractories

2. Analysis of factors affecting heat insulation performance of lightweight refractories
(2) Porosity and characteristics of stomata
The porosity of refractory material is inversely proportional to its thermal conductivity. As the porosity increases, the thermal conductivity rises accordingly. At this point, the performance of lightweight refractories is particularly prominent. But for the same porosity, the smaller the size of the pores and the more uniform the distribution, the smaller the thermal conductivity. When the size of the pores is small to a certain extent, the air in the pores is completely absorbed by the pore walls, so that the inside of the pores is close to a vacuum state, and the thermal conductivity is minimized. When the size of the pores increases to a certain extent, the heat radiation between the inner walls of the pores and the convective heat transfer between the air in the pores increase, and the thermal conductivity rises. According to relevant literature, the heat radiation in small pores is very small, and when the pores are large, especially the long pores along the air flow direction, the efficiency of heat radiation can be increased. Sometimes heat conduction of products with pores can even be better than that of dense products. . The thermal conductivity of closed pores is lower than that of open pores.
Next issue we will continue to introduce factors affecting heat insulation of lightweight refractories. Please stay tuned.