Hello, everybody. I have a problem with, I suppose, easy question. just have limited time and need to get correct answer.
stainless tube L = 2000 mm. Inlet-> Methane 1100 C. 1,5 m3/h. outside air 20 C.
So I need to find out whether a heat exchanger is requited or not.
Everything is clear but I never clearly understood WALL CONDITIONS...what should I choose and why? Heat transfer coefficient or wall temperature? I suppose heat tran coef. but what number? I've done a heat exchanger exmeriment before but they just put 5 W/m2*K without explanation why, where it should be taken from.
And when other parameters must me applied? like surface heat generation rate and wall temperature?
Thank you for explanation in advance and sorry for asking elementary questions.
Hello Alexey,
if you define a wall temperature you get a boundary condition that doesnt change. It is all the time the same temperature.
If you want to take into consideration that the temperature of the outer wall can change then you have to define another wall condition. Wall temperature and heat transfer coefficient could be fine if you know the proper value. The coefficient depends on the used materials and on the state of the flow if it is turbulent or not. If you dont know the value it could be better to run an external analysis, then the software calculates the heat transfer itself.
BR Holger