Experimental study on convective mass transfer in fibrous porous materials within LNG containment systems

Performance degradation of fibrous porous insulation materials in liquefied natural gas (LNG) cargo containment systems (CCS) induced by water vapor intrusion severely endangers the operational safety of LNG carriers. Therefore, research on gas displacement in such materials is a key engineering priority. This study experimentally investigates the forced convection and mass transfer characteristics of fiberglass porous media in LNG CCS, examining how four key parameters — inlet pressure, inlet position, inlet temperature, and porous media bulk density — influence the laws of forced convection and mass transfer as well as the distribution of mass transfer lag zones. A full-scale experimental platform was established to conduct parameter-controlled comparative experiments, with dynamic variation data for temperature, pressure, and dew-point temperatures systematically analyzed. Meanwhile, a quantitative definition method for mass transfer lag zones was proposed to clarify their evolution mechanisms. The results indicate that increasing inlet pressure from 300 Pa to 700 Pa reduces purging time by 42.1%, while increasing porous media bulk density from 32 kg/m3 to 64 kg/m3 effectively eliminates vertical stratification of moisture displacement. A high inlet temperature (95 °C) increases purging time by 11.4% compared with the baseline (35 °C). Mass transfer lag zones are primarily concentrated in the top region of the porous media, and their formation can be effectively suppressed by optimizing inlet parameters and increasing media bulk density. The findings of this study provide a solid experimental basis and technical support for optimizing the gas-displacement process in LNG containment systems and enhancing operational safety.