Numerical investigation on thermal hydraulic performance of supercritical LNG in sinusoidal wavy channel based printed circuit vaporizer

Abstract

As a new type of micro-channel heat exchange, printed circuit heat exchanger (PCHE) is a better choice as main cryogenic heat exchanger (MCHE) on LNG carriers and LNG floating terminals for high efficiency and compactness. In this work, a 3D-numerical model of PCHE employing SST k-ω turbulent model is built after validating against the classic experimental data of supercritical fluid. The cross section of S-LNG channel is a semi-circle with radius of 0.9 mm, size of solid region (stainless steel) is 2.15 mm × 1.6 mm, the overall length of the channel is 500 mm and the centerline formula of the channel is z = 0.5∙sin(0.5∙x). Based on this model, the thermal hydraulic performance of supercritical LNG (S-LNG) in sinusoidal wavy channel of printed circuit vaporizer (PCV) is investigated, and the effects of heat flux and operation pressure on flow and heat transfer are analyzed, which aim to improve the understanding of flow and heat transfer mechanism of S-LNG in sinusoidal wavy semi-circuit channel. Moreover, the simulation result indicates that the maximum gap of heat transfer coefficient between adjacent observation cross section can reach 1.28 kW·m−2·K−1, and the effect of buoyancy force is not domination on heat transfer; the reverse flow occurs nearly in every periodic segment, and the flowing “dead zone” and vortex appear close to the inner wall of cross section, especially near the region of included angle between the straight edge and the semi-circle curve; the lower intensity of both turbulent structure rebuilding and secondary flow appears under higher operating pressure, and after passing large specific heat region, the effect of operating pressure is inappreciable.