Learning Forum

[Ivan Lerga]

Hi!

I'm trying to define pressure losses in a thermal storage system using a porous medium, but I'm having difficulties defining its properties. When comparing the results obtained through Ansys Fluent with those obtained from the Ergun equation, they don't match up.

My system is defined with a porosity of 0.38, density, and viscosity at room temperature, and a particle diameter of 0.006m, with a storage tank length of 0.54m. The velocity is 1.65 m/s in the packed bed. k1=150 and k2=1.75 constant.

I've been reviewing the Ansys guides and I believe the issue lies in calculating the fluid inertia loss. Does anyone know how the coefficient should be calculated?

I have tried this equation, but the units do not match. Because it has to be 1/m.

Thank you very much.

[Rob]

You want to read the Fluent manual, there's a whole section on the porous media and specifically Ergun Equation. Also, a common error is making the Fluent cell zone a different thickness to the actual bed without adjusting the resistance coefficients.