The rate at which heat flows through a material under a temperature gradient, in W/m K, or in US practice as a k-value in BTU in/hr ft2 F. Dense fireclay runs around 1 to 1.5 W/m K, insulating firebrick around 0.15 to 0.4 and ceramic fiber lower still at moderate temperatures, while silicon carbide and carbon-rich brick are many times higher. Lining designers stack layers of different conductivity to hit a target shell temperature.
Run the heat flow calc with the hot thermal conductivity, not the room temperature number off the data sheet.
Also heard as
- k-value
- k-factor
- conductivity
Related terms
IFB
Insulating firebrick: light, porous brick rated by the maximum temperature it can face, such as group 23 or 26.
Hot face
Surface of a refractory lining exposed to the furnace interior, as opposed to the cold face against the shell.
Silicon carbide
Hard, highly conductive refractory used where abrasion, thermal shock and heat transfer all matter.
Insulating castable
Lightweight castable made with porous aggregates that trades strength for low thermal conductivity.