This module is used to compute heat fluxes, temperatures and effective thermal resistance through slabs, long cylinders and spheres under steady state conditions. The module can be used to compute heat transfer for single as well as multiple layers of flat plates, cylinders and spheres. Heat conduction for temperature and heat flux boundary conditions are analyzed using this module.

Heat transfer through layers of slabs : This module calculates heat flux and temperatures through layers of of slabs of different thermal conductivity and thickness. Heat flux through a slab, is computed using equation (1)

(1)

(2)

where :-
aslab - is cross sectional area of slab,
keff - is thermal conductivity of layer,
tin - is inner wall temperature of slab,
tout - is outer wall temperature of slab,
qslab - is heat flux through the slab,
t1 through tn are thicknesses of the various layers and k1 through kn are conductivities of the various layers.

Figure 1

Heat transfer through multiple cylinders : This module calculates heat flux through layers of long cylinders of different thermal conductivity and different thickness. Heat flux through a cylinder, is computed using equation (3).

(3)

Heat flux through multiple layers of cylinders is computed using equation (4).

(4)

For the cylinders, with two layers as an example, the key geomeric dimensions and inputs are depicted in Figure 2.

Figure 2

Heat transfer through multiple spheres :

This module calculates heat flux through layers of spheres of different thermal conductivity and different thickness. Heat flux through a sphere, under temperature boundary condition is computed using equation (5)

(5)

For the spheres, with two layers as an example, the key geomeric dimensions and inputs are depicted in Figure 3.

Figure 3

The inputs for this module are depicted in Figure 4. The inputs consist of a slab geometric dimensions, thermal properties and boundary conditions. The heat coduction through slabs with 3 layers selected as an example tp illustrate the inputs and outputs.

Figure 4: ETBX inputs for Heat Conduction.

The results are displayed using standard ETBX output window shown in Figure 5. The outputs are heat flux, thermal resistance and temperatures at the interfaces between the layers.

Figure 5: ETBX Heat Conduction module outputs.