yusuf uzun
Subscriber

Hi

Thanks for the answer. Now i understand the reason of error, ı guess. I simulated a slice of exchanger geometry and because of that i defined very small mass flow rate at the inlet compared to full exchanger geometry's mass flow rate. I know that Fluent scales the NTU value depending on mass flow rate. When i transfer flow-dependent heat transfer data from case of slice geometry to case of full geometry, mass flow rate data might be  too small to interpolate. I guess Mass Flow Rate point of full heat exchanger exceeds area of can be interpolated. 
Is my detection wrong?
Is the method that i following to perform the dual cell model right?

If it's not, how should be the method?