T-junctions in a hydronic system

Abstract

The OpenFoam software with the Computational Fluid Dynamics (CFD) theory is used in this thesis. In this paper the importance of grid resolution and layers are shown. Four different grid resolutions with about 30& reduction each time on the original cell amount with or without layers are compared. The applicability of Reynolds Average Navier-Stokes (RANS) Shear Stress Transport (SST) k�����! model on the turbulent flow in a T-junction are investigated. There is done a validation study on the T-junction with ndirect comparison to an experiment preformed by the collaboration of OECD/NEA and Vattenfall Research and Development at the Älvkarleby Laboratory in Sweden. The effect two adjacent branches in a T-junction have on each other is also looked into. A double T-junction with different spacing, 600mm, 2.5D, 2D and 1.5D, between are simulated. The comparisons are done visual by looking at the flow profile, stream tracers, surface lic and the bulk velocity in the middle of the branches. It was found that the best configuration that disturb the recirculation zone the least is between 2 and 2.5D for this case when the closeness of the branches are of importance.