Heat transfer enhancement in a large-scale Ti-Mn based metal hydride storage reactor with nanofluids using open source CFD software

Abstract

Metals can safely store hydrogen with high energy densities in the form of metal hydrides through an exothermic process. However, the slow hydrogen absorption kinetics significantly decreases its storage rate. Ensuring efficient heat dissipation from the metal hydride bed can result in a faster charging rate, which in turn improves the storage performance. The objective of this work is to improve the rate of heat and mass transfer in a Ti-Mn-based metal hydrides reactor for large-scale applications using a 3D model. Finite volume simulations with OpenFOAM software were conducted to investigate the influence of various parameters on the hydride reactors’ performance. Water-based alumina (Al2O3/H2O) nanofluid with varying volume fractions up to 5% are used as heat transfer fluids. The results show that accelerating the coolant flow velocity, decreasing its inlet temperature, and increasing the hydrogen supply pressure contribute further to enhancing thermal performance. Compared to pure water, the Al2O3/H2O nanofluid with 5 vol % can improve heat transfer by approximately 11.5%. This can reduce the time needed to reach 90% storage by 18.1%. Also, the pressure drop throughout the hydride reactor at different flow velocities is slightly greater than that in pure water.

Keywords

• hydrogen storage
• heat and mass transfer
• nanofluid
• openfoam