Numerical study on multiphase flow and heat-mass transfer in high-pressure aluminum-water reactors with liquid water and steam

Aluminum has considerable potential as a hydrogen carrier. Its reaction with water under high-temperature and high-pressure conditions enables catalyst-free cogeneration of hydrogen and high-grade heat without direct carbon emissions. However, the reactor-scale flow, heat transfer, and mass transfer mechanisms remain insufficiently understood. This work develops CFD models for aluminum reactions with liquid water and steam, coupled with UDFs describing aluminum-core shrinkage and product-layer growth. The models represent reaction initiation, development, and decay, and are used to analyze particle size, inlet temperature, water-to-aluminum molar ratio, and pressure. Results show that larger particles weaken activation, shift heat release downstream, and reduce outlet temperature. In the liquid-water reactor, outlet temperature reaches 591.2 K at 15 MPa and hydrogen volume fraction reaches 99.90%. In the steam reactor, outlet temperature reaches 1848.7 K at 10 MPa, while pressure increases hydrogen mole fraction but reduces volumetric gas output.