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# Validation Case: Heat Transfer in a Composite Wall

In this case, a composite wall consisting of two layers (an insulating brick wall on the outside and a fire brick wall on the inside) surrounds a furnace. Thermal convection boundary conditions are used on the inside of the fire brick wall and on the outside of the insulating brick wall to represent the transfer of heat from the brick to the air. The aim of the analysis is to determine the temperatures on the interfaces of the composite wall.

Comparison of the simulation results against the analytical calculations validates the use of following conditions for static thermal analysis in Solve:

• Convection

## Material

• Fire Brick
• Thermal Conductivity (k1) = 1.38 W/mC
• Insulating Brick
• Thermal Conductivity (k2) = 0.17 W/mC

## Physics

• Convection
• Fire Brick Top
• Reference Temperature in far-field (Tin): 1700 °C
• Convection Coefficient (h1): 68 W/m2C
• Insulating Brick Bottom
• Reference Temperature in far-field (Tout):  26 °C
• Convection Coefficient (h2): 11 W/m2C ## Meshing

OnScale Solve generated the mesh automatically and the meshing statistics, at the time of writing this document,  are as follows:

Mesh Quality: Medium

## Reference Solution

The thermal resistance at each point of the composite wall is given by: Where A is the cross-sectional area of the wall which is constant.

The total thermal resistance of the wall is given by: The heat transfer rate through the wall is given by: Calculating the heat transfer rate through the wall allows the calculation of the temperature at each point of the wall using: ## Results Comparison

The table below compares the values obtained using the analytical methods described above and the FEA analysis performed using OnScale Solve.

Result Quantity Analytical (°C) OnScale Solve (°C)
T1  1670.7 1670.7
T2  1381.4 1381.4
T3  207.4 207.4

Note, probe capability through SimAPI was used to extract the temperature values from the model. 