CFD Investigations on the Liquid Nitrogen Chill down of Straight Transfer Lines and ITS Comparison with Helically Coiled Transfer Lines

Abstract

Attempts are constantly being made to simulate the momentum and energy interactions involved in cryogenic chill-down process accurately as in real case through CFD. The main difficulty is the lack of reliable data and correlations that compass the parameters associated with cryogenic fluids. This work has taken the much needed first step in studying the effect of varying transfer line geometries on their corresponding chill-down times. Chill-down in helical transfer lines were investigated using validated computational fluid dynamics code (FLUENT 15.0). The time taken to completely chill-down a straight as opposed to a helical transfer line, at constant heat flux, was compared in this study. Important flow quantities for multiphase system such as volume fraction distribution were plotted and displayed. It was found that centrifugal forces due to shape of helical transfer lines play an important role in the phase and temperature distribution in helical pipes. It was also observed that the time taken for complete chill-down of helical transfer lines were much smaller as opposed to a straight transfer lines. It is concluded that future studies are required with improvements in the prediction scheme with detailed two phase correlations.