## Fluids

Topics relate to Fluent, CFX, Turbogrid and more

#### study on mass flow rate of methane

• ITALO FIRMINO DA SILVA
Subscriber

Hi guys, i'm Italo and I'm a student of energy engineering!

I'm facing a challenger of my termodynamics professor to create a case of a tank with a vent to prevent over pressure where there is methane under pressure in two-phase state. There's heat flowing from enviroment to the interior which causes phase change (boil off). My question is:

1 - How can I construct a vent-like object what acts like a overpressure valve?

Although I have made some research about the theme, nothing useful was found. I try some papers, youtube tutorials, even the officials tutorials of Ansys.  Actually, that issue could be a new tutorial, isn't. "Simulation of boil off methane with mass flow rate measurement in a vent (or valve)"

2 - If is impossible build such object, how can I measure the mass that is being convert in gas in respect of time in Ansys? That is a typical mass and heat transfer problem.

• Federico Alzamora Previtali
Subscriber

For your first question, Fluent has a Outlet Vent boundary type 7.4. Boundary Conditions (ansys.com). Hence, you can construct your tank, set the appropriate thermal boundary conditions on the external walls and have one boundary defined as an outlet vent, where you can set up a mass flow rate monitor.

• ITALO FIRMINO DA SILVA
Subscriber

I cannot access the link to find out how to set a boundary condition for outlet vent. Should I build the outlet vent with atmosphere contact in the geometry step? Or should I build a fully closed surface and when set as outlet vent the Ansys do the rest?

• Federico Alzamora Previtali
Subscriber

To access the User Manual, you can click on Help from the Fluent Launcher window.

In the geometry step, you should create a boundary zone, which will correspond with your outlet vent. You can then assign the appropriate boundary type and conditions in Fluent.