Hy, everyone! Please tell me where i'm rong:

I have a cylinder 20 m lenght, diameter 3.7 m (volume V = 215.04 m3) i have valls (lateral), inlet and outlet. mass flow inlet m = 20 kg/s water liquid temperature 20 C (T1 = 298 K) i want to have a outflow temperature of 90 C (T2 = 363 K) The necesary heat for that is Q = m*cp*(T2 - T1) Q = 20 kg/s * 4182 J/kgK * (363 - 298) = 5,854,800 W

Surce Terms = q = Q / V = 27226 W /m3

So after the calculation i must have at exit 363 K But i have 443 K

Can you explain this?

Thank you!

Mihai

Maybe your problem setup is incorrect. i did a short calculation for your pipe with a 50k cell mesh and your bc. fluent calculated a mass-weigthed average of 364K at the exit. looks ok by me.

rom

thanks for your answer! It is like you said! I found the mistake. It was under my nose. ) Mihai