Component effect on the flow and heat transfer of supercritical liquefied natural gas in a submerged combustion vaporizer

A submerged combustion vaporizer (SCV) is a popular vaporizer that is utilized for the peak regulation of liquefied natural gas (LNG) in cities or as the main vaporizer in cold regions. Due to the different genesis of reservoirs, LNGs from different production places have different components and ratios, leading to a different gasification state in the heating tube, difficultly in predicting the SCV thermal performance, and difficulty in controlling the water bath temperature and gas consumption to combust during SCV operation. Therefore, in this study, a numerical model of the heating tube in SCV is established and the flow and heat transfer features of three types of LNGs with different components are compared with those of pure methane. Moreover, the heat transfer and thermal performances of supercritical LNG in a serpentine tube are analyzed under various operating pressures and thermophysical properties. The results indicate that higher the ratio of methane, larger the heat transfer capacity, closer the comprehensive pseudo-critical temperature of LNG is to that of pure methane, and the more similar is the thermal performance. Furthermore, the SCV thermal performance decreases with the ratio of pure methane. The smallest Euler number is observed for LNG from ChangYi (C.Y.) because of its smallest dynamic viscosity and highest specific heat among the observed LNGs; thus, its Nu/Eu and eta are better than those of pure methane and it has a higher outlet temperature for the gasification rate.