Inquiry Regarding Air Permeability Simulation

[YueYan]

Dear Delphin-Team,

I hope this email finds you well. I am writing to inquire about some issues I encountered while simulating the effects of air permeability on heat and moisture transfer in porous materials.

When simulating the influence of air permeability in porous materials, I encountered a few challenges and would greatly appreciate your guidance and advice. Here are the specific questions:

Firstly, I disabled "Air tight" in the material editing window and created a "Moisture dependent spline" in the material function section. However, regardless of the material used, the Kg consistently shows as 0.0001s when the Θl is set to 0. Could you please confirm whether the Kg values in the material function library represent actual data? Is there a need for modification?

When setting boundary conditions, I need to input indoor and outdoor pressures to calculate the pressure difference. However, the "exchange coefficient for still air" field at the bottom requires input. After consulting the Delphin5 manual, the recommended value is 1000s/m. Could you clarify whether the recommended value for indoor and outdoor pressure is the same?

According to the model's formula for air convection mass flux, the air convection mass flux equals the air mass concentration in the gas phase multiplied by the gas phase flow rate. The gas phase flow rate is related to the material's permeability (Kg) and pressure gradient. I would like to inquire about which part of the simulation process reflects the setting of the exchange coefficient for still air.

Thank you very much for taking the time to read my email. I look forward to your response and guidance

[fechner]

Hello,

The Kg value in the material data represents the air flow conductivity. It depends on the air tightness of the certain material. The only material in the Delphin database with a measured Kg is mineral wool. You can have a look there for reference values. The most other materials should have lower values.

The exchange value for the boundary condition should have a value of 2. This value is selected corresponding to measurements from the university of Kaiserslautern in Germany. As far as I know the paper is not available in English.

I will send you additional information by email.

[YueYan]

Hello,
Thank you very much, I will be looking forward to your email reply!

[YueYan]

Hello,
I seem to have not received your email. Could you please send it again?