Numerical investigation of natural circulation in a 2D-annular closed-loop thermosyphon

This work aims to investigate the natural convection in a water-filled closed-loop. A numerical study of laminar, two-dimensional natural convection in an annular thermosyphon is reported, the loop being heated at a constant flux over the bottom half and cooled at a constant temperature over the top half. The annular thermosyphon configuration which is the subject of this study has never been investigated previously. It is numerically demonstrated that the complexity of the dynamic properties encountered in the experimental studies of toroidal or rectangular loops, is found here: steady flow with and without recirculating regions, periodic motion and Lorenz-like chaotic flow. The numerical work also aims to simulate the variation of mass flow rate and heat transfer behaviors where the driving parameters and correlations which are non-loop specific are also given.