Numerical Investigation of AB2 Metal Hydride Systems for Hydrogen Storage.
Ntswana, Molefe
Ntswana, Molefe
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Abstract
The are many challenges that are to be overcome to establish the substantial ground to develop an effective solution for on board hydrogen storage in the field of metals, hydrogen, and storage system. In this study, numerical investigation i.e. modelling and simulation of hydrogen storage in AB2 type metal hydride packed inside the reactor was performed. The study focused on the development of coupled energy and mass models describing heat and mass transfer taking place between gas and solid metal hydride during absorption and desorption processes inside the reactor. The developed models were solved with the aid of the COMSOL 5.2 Multiphysics simulation tool. The simulation results demonstrated the importance of mutual dependence between temperature propagation in the body of metal hydride, the absorbed concentration of hydrogen, and the gas pressure of absorption/desorption of hydrogen gas in the metal hydride. The results clearly demonstrated that temperature plays a pivotal role in influencing the sorption process. The absorption, process was observed to be favoured by a range of temperatures from low to high, with concentration increasing as the temperature rises. This trend was also observed in the behaviour of pressure and velocity. Conversely, when pressure is increased from a lower level to a higher level, the opposite effect is observed. Furthermore, it was discovered that the ideal operation conditions for temperature and pressure were 303.15 K and 10 atm. The observation of desorption suggests that the process is endothermic, but it does not necessitate excessively high temperatures. With 293.15 K being a favourable operating temperature, and 3 atm for pressure. The pressure discharge in desorption in vice versa to that of absorption. In summary, it can be concluded that high temperatures are conducive for absorption but are less favourable for desorption processes. Desorption in general is favoured by condition close to ambient conditions. And it was recommended that disruptive metals should be discovered for hydrogen sorption in order for hydrogen economy to be established at a lower cost.
Description
Submitted in partial fulfilment of the requirements in research for degree, Masters in Engineering: Chemical (Structured & Research) in the Department of Chemical, Metallurgical, and Materials Engineering in the Faculty of engineering and the built environment at the Tshwane University of Technology.
Date
2023-01-01
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Tshwane University of Technology
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Keywords
Hydrogen, Metal hydride reactor, Absorption/desorption, Heat and mass transfer, Simulation and COMSOL