Porous model

jack

Hello, I am using the porous model of fluent for heat exchanger. I am using NTU model, fixing the heat rejection value. I set all values for the core porous model, following some results that I found with some other program like pressure drop, area. I am quite sure of this values that I input. The core friction factor was actually my only unknown that I calculate by those values. My problem is that, by post processing, I found out a pressure drop of 0.5 bars in my primary gas through the HE when I set a porous model for the heat exchanger based on a pressure drop of 100Pa. Lets say almost a coefficient of 1000. Again, I checked my values. And when you set the heat exchanger model in define, it actually affects the values of inertial resistance in the BC of the volume corresponding to the heat exchanger. After doubting of me, I allow myself to assume that it could have an error in the equation of this porous model. Is there anyone who had got the same pressure drop as he was expected using this NTU model with fluent? Please I am really screwed, so ur help will be welcome. By the way I am using fluent 6.3 Thank u in advance.