A review of interfacial mass transfer mechanisms in the batch transportation of methanol and refined products

The sequential transportation of methanol via existing refined product pipelines is a critical pathway for its large-scale, low-cost, and long-distance distribution. However, the significant physicochemical differences between methanol and refined products (gasoline, diesel) lead to complex interfacial mass transfer phenomena, posing severe challenges to transmix prediction and operational safety. This paper systematically elucidates the interfacial mass transfer mechanisms during the sequential transportation of methanol and refined products from the perspective of multi-scale study, ranging from microscopic intermolecular forces to macroscopic interfacial mass transfer. The comprehensive impacts of media properties, composition, and external operating conditions on the mass transfer mechanisms and interfacial behavior are further evaluated. The study reveals the dualistic characteristics of interfacial mass transfer in the methanol-refined product system: the miscible methanol-gasoline system forms a single-phase miscible zone dominated by Taylor-Aris dispersion, whereas the immiscible methanol-diesel system exhibits a multiphase flow phenomenon governed by gravity stratification and shear emulsification. These findings highlight the limitations of the traditional convection-diffusion model in predicting the behavior of such complex interfaces. Future research should focus on the development of the multi-scale mass transfer prediction model capable of coupling thermodynamic phase equilibrium with fluid dynamics, and on the acquisition of systematic experimental data needed to support the model's validation and application. This study can provide a solid theoretical foundation for achieving the safe and efficient sequential pipeline transportation of methanol and refined products.