ENGINEERING – THERMODYNAMIC & HVAC CALCULATOR
Conduction Heat Flux
A precise tool.
What is the Conduction Heat Flux & How does it work?
In steadyβstate oneβdimensional conduction, the temperature profile across a homogeneous slab is linear. The heat that flows per unit area, called the heat flux (q”), depends only on the materialβs ability to conduct heat (thermal conductivity (k)), the temperature difference between the two faces ((Delta T)), and the slab thickness ((L)). Fourierβs law formalises this relationship: the greater the conductivity or the larger the temperature drop, the more heat passes through; conversely, a thicker slab offers more resistance and reduces the flux. This principle underpins the design of building envelopes, heat exchangers, and insulation systems. Because the law is linear, engineers can quickly estimate required insulation thickness or predict heat loss by rearranging the equation. The result is a convenient expression for heat flux that can be evaluated with just three input parameters, making it ideal for quickβlook calculators and preliminary design checks.
q” = \frac{k\,\Delta T}{L}
q” = heat flux (W/mΒ²)
k = thermal conductivity (W/mΒ·K)
\Delta T = temperature difference (K)
L = slab thickness (m)
k = thermal conductivity (W/mΒ·K)
\Delta T = temperature difference (K)
L = slab thickness (m)
Parameters
Result
β
Frequently Asked Questions
What is conduction heat flux?
Conduction heat flux is the amount of heat that flows per unit area across a material due to a temperature gradient.
How does thermal conductivity affect heat flux?
Higher thermal conductivity means more heat can pass through for a given temperature difference and slab thickness.
What is Fourier’s law in the context of heat transfer?
Fourier’s law states that the heat flux is proportional to the negative gradient of temperature and the material’s thermal conductivity.
How do I calculate the temperature difference for heat flux?
Subtract the temperature at one face of the slab from the temperature at the other face.
What units are used for heat flux in this calculator?
Heat flux is typically measured in watts per square meter (W/mΒ²).
Can this calculator be used for non-homogeneous materials?
No, this calculator assumes a homogeneous slab with constant thermal conductivity.
What happens to heat flux if the slab thickness increases?
Increasing the slab thickness decreases the heat flux for a given temperature difference and thermal conductivity.
Results are for informational purposes only and do not constitute professional advice.