High pressure ammonia dissociation experiments for solar energy transport and storage

Work relating to the application of the ammonia dissociation reaction to the thermochemical transport and storage of solar energy is reported. A two-dimensional pseudo-homogeneous packed-bed catalytic reactor model has been adapted to predict the behaviour of ammonia dissociation and synthesis reactors. A series of steady-state experiments, with a high-pressure ammonia dissociator operated in an ‘open-loop’ experimental configuration, have been used to verify the model. These experiments involved operating pressures up to 16 MPa and temperatures up to 720°C. The results indicated an activation energy of 192 kJ mol⁻¹ and a pre-exponential factor of 3.0 × 10⁷mol s⁻¹ cm⁻³ atm⁻¹ for the nickel-on-alumina dissociation catalyst used. The experiments also indicated that the experimental configuration is suitable for development into a ‘closed-loop’ energy storage experiment operating at a power level of approximately 1kW_chem.