January 2014 - Fluid Interactive

Thanks to U-factors feature of Mold Simulator 3, it is possible to compute the contribution of every room to global psi value of a thermal bridge. In this tutorial we’ll refer to file example13.mos contained in Mold Simulator’s documentation folder.
Suppose you’ve a T type of thermal bridge:

It is very important to create two different section elements (“Top element” and “Bottom element”) to get correct results.
We want to use four different boundary conditions for the internal environments; for this reason you must pay particular attention to boundaries setup.
1- Every internal boundary must have the same temperature;
2- Grouping must be by temperature, but you must disable “Just connected boundaries” option;
3- A separate U-factor surface must be associated to each boundary;
4- U-factors of room A must be grouped under “Room A” U-factors group (same for U-factors of room B).

Now you’re ready to get separate linear thermal transmittance contributions of this thermal bridge simply passing to simulation tab.

In many thermal bridge computations, you can choose the reference point against which to calculate the linear thermal transmittance (psi). The most common example is the edge of a building:

It is possible to calculate psi compared to the internal reference point (lengths A and B) or outside (C and D). Thanks to Mold Simulator 3’s new features, you can do both with a single project following these simple steps:
1- plot the section elements to identify lengths C and D of the thermal bridge:

2- change the properties of the newly created items by enabling the “double-length” option. Some new lines will appear for each item;
3- adapt to the new lines in order to identify the lengths A and B:

Turning to “Simulation” tab, you will notice two distinct values of thermal bridge’s linear thermal transmittance (psi): one refers to the internal reference point and the other one to the outside point. For more information, please go to Mold Simulator page.

Separate psi contributions with U-factors

Internal or external linear thermal transmittance in a thermal bridge

Archive for month: January, 2014