Solid heat transfer in FDS

[Ste]

Hello everybody,

I have two doubts about FDS heat transfer model. I understood that the model is a 1D model, but here there are my questions.

1) I have a heater with a fixed temperature applied to lower z surface of obstruction 1 (see picture "fds without obstacle) and I want to calculate final wall temperature of upper z surface of obstruction 2. In this case I can see the air temperature increase by means of slice file (as you can see from picture), but the device (solid phase device, adiabatic surface temperture) does not record any temperature increase..is there any setting error? Maybe the solid phase device has to be set as "wall temperature"?

2) Same case as above but with an obstacle between heater (obstruction 1) and target surface (obstruction 2) represented by 3 in picture "fds with obstacle". In this case by means of slice file I can see the temperature increasing in the space between 1 and 3, but I can't see the temperature increasing between 3 and 2. I would expect FDS to calculate the solid heat transfer in obstruction 3 and then to calculate the air temperature increasing between 3 and 2..is this possible? I set thermal parameters (specific heat, conductivity) of materials.

Thank you in advance (please take in mind that I am FDS beginner, I am still learning!).

Regards,

Ste

[dr_jfloyd]

See 8.3.3 Back Side Boundary Conditions

In brief, FDS currently only predicts the backside temperature for a single OBST that is no more than one cell thick.  Anything else (two or more cells thick or more than one OBST) and the backside boundary condition is is considered to be the ambient.  For now, if you want to account for heat transfer through multiple layers, just define multiple layers on one OBST input.

[Ste]

Thank you very much dr_jfloyd!

Another stupid question: when using a solid phase device and I am interested in the temperature values on a obstacle surface, is it correct to set as parameter "wall temperature" (considering the right normal of solid direction, of course)? Adiabatic surface temperature only takes into account the heating of the surface without any further heat transmission, is it right?

Thank you again!

Stefano

[dr_jfloyd]

Yes on both. See:

16.2.1 Single Point Output

Devices on Solid Surfaces

8.2.3 Special Topic Adiabatic Surfaces

[Ste]

Thank you!