Numerical study on storage performance of metal hydride reactors with multiple spiral fins

Metal hydride (MH) is an efficient hydrogen storage method with high density and moderate operating conditions. Thermal management is required for hydrogen storage and release to cope with the strong thermal effects generated by the reaction. The MH reactor with spiral fins is proposed to improve the hydrogen storage efficiency by increasing the heat transfer characteristics of the reactor. The hydrogen absorption and desorption performances of the MH reactors with different spiral fin structures have been discussed. The results show that the MH reactor with spiral fins present better reaction performance compared to that of the MH reactor with longitudinal fins. And the larger the fin spiral cycle (SC), the faster the reaction rate. The hydrogenation time and dehydrogenation time could be maximally reduced 29.8% and 29.2% with fin spiral cycle increasing from 1/4 to 1, where the hydrogen storage density kept constant. The hydrogenation time and dehydrogenation time could be reduced 53.1% and 34.7% with fin number (FN) increasing from 4 to 16, while the hydrogen storage density is reduced 24.1%. Keep the volume of fins consistent, the fin number and fin thickness (FT) are optimized, and the results are FN = 8, SC = 1, FT = 1 mm, the corresponding hydrogen storage density is 0.087 g mm−1. The performance of the reactor with the optimal fin parameters under different operation conditions was also analyzed. The recommended operation parameters are concluded as the hydrogen pressure of 1.0 MPa for absorption and 0.1 MPa for desorption, heat transfer wall temperature of 293.15 K for absorption and 353.15 K for desorption.