Optimal design of a metal hydride hydrogen storage bed using a helical coil heat exchanger along with a central return tube during the absorption process. (19th April 2021)

• Record Type: Journal Article
• Authors: Eisapour, Amir Hossein; Naghizadeh, Ali; Eisapour, Mehdi; Talebizadehsardari, Pouyan
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 27(2021)
• Page Start: 14478
• Page End: 14493
• Publication Date: 2021-04-19
• Subjects: Magnesium based metal hydride reactor -- Hydrogen absorption -- Helical coil heat exchanger -- Reaction time -- Heat transfer; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.01.170
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Metal-hydride (MH) reactors are one of the most promising approaches for hydrogen storage because of their low operating pressure, high storage volumetric density and high security. However, the heat transfer performance of the MH reactor for high hydrogenation rate is inferior. In this study, the heat transfer and hydrogen absorption process of metal hydride tank performance in Mg2 Ni bed is analyzed numerically using commercial ANSYS-FLUENT software. The MH reactor is considered a cylindrical bed including a helical tube along with a central straight return tube for the cooling fluid. The effects of geometrical parameters including the tube diameter, the pitch size and the coil diameter as well as operational parameters on the heat exchanged and hydrogen absorption reactive time are evaluated comprehensively. The results showed that the helical heat exchanger along with central return tube could effectively improve heat exchanged between the cooling fluid and the metal alloy and reduce the temperature of the bed results in a higher rate of hydrogen absorption. For a proper configuration and geometry of the helical coil heat exchanger with a central return tube, the absorption reaction time is reduced by 24% to reach 90% of the storage capacity. After the optimization study of the geometrical parameters, a system with the heat exchanger tube diameter of 5 mm, coil diameter of 18 mm and the coil pitch value of 10 mm is recommended to have lower hydrogen absorption time and higher hydrogen storage capacity. The presented MH reactor can be applied for improvement of heat exchange and absorption process in industrial MH reactors. Highlights: Study on metal hydride reactor with a magnesium bed during the absorption process. Use of helical coil heat exchanger with a central return tube in metal hydride. 24% saving in the absorption time using a central return tube in the helical coil. Optimize the absorption process based on geometrical and operational parameters.