Numerical optimization of a passive internal heat exchanger for stationary MH-storage applications

The present study evaluates internal passive heat exchanger designs to identify the most effective configuration for supplying hydrogen to fuel cells with a power output between 5 and 31.2 kW el . Finite element method (FEM) simulations in 2D are conducted for transversal horizontal, spiral, and radial aluminum fin structures. The model is validated using a prototype vessel containing an AB 2 hydride alloy with a hydrogen storage capacity of approximately 240 g. The findings of this investigation suggest that a radial fin design comprising 16 fins with thicknesses ranging from 2 to 5 mm offers the best heat transfer performance. This configuration offers the optimal balance among hydrogen release, tank mass, and fuel cell supply duration under both low- and high-flow conditions. Furthermore, a dimensionless-number-based tool has been introduced to facilitate geometry-independent design optimization and performance prediction for passive heat-transfer structures.