Learning Forum

[zain.qazi]

Hello.

I am using the RPI model to simulate nitrogen evaporation in a horizontal cooling channel. Most literature related to the RPI model and even the fluent verification case for subcooled flow boiling is for vertical pipes (nuclear applications). My aim is to achieve enhanced wall cooling and increased heat flux due to the boiling phenomenon which is something I am not experiencing. The volume fraction goes up very fast at even lower wall temperatures. 

 

Could this be because of buoyancy effects as the gravity is perpendicular to the flow direction and the force models are not effective meaning that the liquid phase is already being pulled to the wall due to gravity and vaporizing almost instantly? Does the RPI model then work for horizontal pipe flow cases?

[Rob]

The model will work in that it's a phase change model, but was validated for vertical pipes so may not be appropriate. As I don't know what you're seeing, and whether the solution is converged it's a little difficult to comment further.