Multiphase reactors are most widely encountered in chemical

metallurgical

energy and pharmaceutical industries. Because multiphase flow in reactors is generally unstable

nonlinear and non-equilibrium in nature

many challenges are exerted to multiphase flow detection technology. It has always been one of the frontier studies in process engineering to accurately measure and comprehend multiphase hydrodynamics

as well as to discover and master rules for design and scale-up of multiphase reactors. Magnetic resonance image (MRI) technology

an advanced non-invasive detection method

can obtain accurate and detail information of multi-dimensional transient fields

such as transient solid concentrations

velocity (fluctuating) fields

flow pattern recognition

bubble vortex structure

particle clustering

and meso-scale heterogeneous structures. Additionally

MRI could have good prospective applications for validation and improvement of numerical models. This review discussed MRI principle

analyzed current status of MRI application for gas-solid and gas-liquid flow hydrodynamics

and prospected promising future directions.