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open-ideas / IDEAS

Modelica library allowing simultaneous transient simulation of thermal and electrical systems at both building and feeder level.
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Thermal models of non-homogeneous walls #327

Closed Mathadon closed 9 years ago

Mathadon commented 9 years ago

Walls currently assume homogeneous properties for density, heat capacity and thermal conductivity. However for wall components such as hollow concrete blocks this approximation could be improved. It would be nice if we had some types that take into account this non-homogenity. Does any of you know good thermal models for this?

GlennReynders commented 9 years ago

Filip,

Typically an equivalent U-value or lambda-value is calculated to implement these effects. I don't think this feature is needed for general purpose modelling. However, thermal bridging effects (2D or 3D) are a different matter and could be an important improvement.

G.

2015-03-25 9:29 GMT+01:00 Filip notifications@github.com:

Walls currently assume homogeneous properties for density, heat capacity and thermal conductivity. However for wall components such as hollow concrete blocks this approximation could be improved. It would be nice if we had some types that take into account this non-homogenity. Does any of you know good thermal models for this?

— Reply to this email directly or view it on GitHub https://github.com/open-ideas/IDEAS/issues/327.

Mathadon commented 9 years ago

I agree that it's not relevant for most applications but I'm noticing the influence of the wall structure in one of my temperature sensor readings.. =) Do you have a reference for the equivalent U-value that I can have a look at?

rubenbaetens commented 9 years ago

@Mathadon the one-dimensional thermal resistance of two parallel thermal resistors is basic physics, no ? http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node118.html

Mathadon commented 9 years ago

This solution is ok.