Analysis and prediction of heat transfer deterioration of supercritical pressure cryogenic methane in a vertical tube

Developing a compact vaporizer with high thermal efficiency is of great significance to the storage and usage of Liquid Natural Gas (LNG). Numerical simulations were performed to investigate the flow and heat transfer characteristics of supercritical pressure methane in a vertical tube, and primary focus was to reveal the mechanism of two-peak wall temperatures occurrence. Six turbulent models have been confronted with experimental data, and the Renormalization Group (RNG) k-epsilon model is adopted. When Heat Transfer Deterioration (HTD) occurs, two-peak wall temperatures appear in the upward flow with high mass flux. The phenomenon of two-peak wall temperatures were explained in detail based on radial distributions of velocity and turbulent kinetic energy at different axial positions. The M-shape velocity distribution promotes the generation of turbulence in the core region. The reversal of radial flow direction enhances the mixing between hot and cold fluids. A new criterion was proposed for predicting the critical heat flux which causes the onset of HTD in supercritical pressure methane. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the flow and heat transfer characteristics of supercritical pressure methane in a vertical tube, focusing on the mechanism of two-peak wall temperatures occurrence. The M-shape velocity distribution and reversal of radial flow direction play key roles in promoting turbulence and enhancing mixing between hot and cold fluids. A new criterion for predicting critical heat flux causing heat transfer deterioration in supercritical pressure methane is proposed.