Simulation of Heat Transfer and System Behavior in a Supercritical CO2 Based Thermosyphon: Effect of Pipe Diameter

Abstract

This paper deals with the natural convective circulation thermosyphon with supercritical CO2 flow. New heat transport model aiming at supercritical thermosyphon heat transfer and stability is proposed and numerically studied. Two-dimensional rectangular natural circulation loop model is set up and the effect of pipe diameter is systematically analyzed. Finite volume method is used to solve the conservative equations with supercritical turbulence model incorporated. It is found that supercritical CO2 thermosyphon can achieve high Reynolds flow as 104–105 even temperature differences between source and sink is small. Stabilized flow is found for larger pipe diameter group due to the developed flow field and enhanced heat transfer. Heat transport at cooler side can be enhanced at higher operating temperature and be critical for the stabilization of the supercritical thermosyphon. Correlations of flow and heat transfer are reexamined and good agreements with classical reports are also obtained in the present study.