Numerical Analysis of Phase Change and Natural Convection Phenomena During Pipe Freezing Process

A numerical analysis is performed in this study to see the characteristics of the ice plug formation and the heat transfer during pipe freezing process. The unsteady three dimensional computer code which solves incompressible Navier-Stokes equations including energy equation has been developed in this study. The computed results for verification including phase interface and flow patterns showed good agreements with others. And additional pipe freezing experiments for verification showed that maximum flow rate for the complete plug formation is highly dependent on the pipe diameter and length of jacket containing refrigerant (LN₂). The results of pipe freezing experiments could be also used as a guideline and to the proper computation. It was found that the effects of pipe diameter and freezing jacket length on the ice plug formation are significant. It was also found that this bi-cellular vortex oscillates in an axial section (r – z plane) as moves to downstream. Finally, the numerical results showed that the characteristics of the flow in the mushy region influence the shape and the freezing time of ice plug formation.