Engineering tool
Refractory Wall Heat Loss Calculator
Calculate the steady-state heat flux through a refractory wall from its thermal conductivity, thickness and the temperature difference across it.
Heat flux — W/m²
Heat flux — kW/m²
Pick a material to fill in a typical conductivity, or type k directly. Thickness in millimetres.
Formulas used
- Heat flux q (W/m²) = k × (T_hot − T_cold) ÷ thickness
- k in W/m·K, thickness in metres
Practical notes
- This is one-dimensional steady-state conduction through a single layer. A real lining has several layers and a surface film, which lower the flux.
- Conductivity rises with temperature for most refractories and falls for graphite and SiC; a single k is an approximation over the working range.
- Halving the flux does not require halving the temperature — thickness and conductivity are the levers you actually control.
Frequently asked questions
Why is my calculated loss higher than measured?
A single-layer calculation ignores the backup insulation, the shell and the outside air film. Each adds resistance, so the real flux is lower.
Which k should I use?
Use the value at the mean wall temperature, not at the hot face. Supplier datasheets normally give k at several temperatures.