Design optimization of a magnesium-based metal hydride hydrogen energy storage system

Abstract

Metal hydrides (MH) are known as one of the most suitable material groups for hydrogen energy storage because of their large hydrogen storage capacity, low operating pressure, and high safety. However, their slow hydrogen absorption kinetics significantly decreases storage performance. Faster heat removal from MH storage can play an essential role to enhance its hydrogen absorption rate, resulting in better storage performance. In this regard, the present study aims to improve heat transfer performance to positively impact the hydrogen absorption rate of MH storage systems. A novel semi-cylindrical coil is first designed and optimized for hydrogen storage and embedded as an internal heat exchanger with air as the heat transfer fluid (HTF). The effect of novel heat exchanger configurations is analyzed and compared with normal helical coil geometry, based on various pitch sizes. Furthermore, the operating parameters of MH storage and HTF are numerically investigated to obtain optimal values. ANSYS Fluent 2020 R2 is utilized for the numerical simulations. Results from this study demonstrate that MH storage performance is significantly improved by using a semi-cylindrical coil heat exchanger (SCHE). The hydrogen absorption duration reduces by 59% compared to a normal helical coil heat exchanger. The lowest coil pitch from SCHE leads to a 61% reduction of the absorption time. In terms of operating parameters for the MH storage with SCHE, all selected parameters provide a major improvement in the hydrogen absorption process, especially the inlet temperature of the HTF.

Hydrogen storage properties of magnesium based alloys Mg67Ni(32-x)Nb1Alx (x = 1, 3, and 5) by using response surface methodology

“…For the developed empirical model, the R 2 value of 0.983 is inferred to be relatively high, which strongly indicates 98.30% agreement between experimental and predicted discharge capacities. The regression coefficients of the second-order polynomial equation are shown in table 4.…”

“…The efficiency of energy-based materials such as hydrogen storage materials, battery materials, etc. is highly improved by adopting newly developed processing techniques [1][2][3][4]. Hydrogen is the most attractive energy carrier due to its high gravimetric energy density and lower heating value of 33.3 kWh /kg compared to gasoline 12.4 kWh/kg and natural gas 13.9 kWh/kg [5,6].…”

Hetero-atom doped graphene for marvellous hydrogen storage: unveiling recent advances and future pathways

“…The enthalpy of adsorption for hydrogen to these materials is very high, which shows a strong interaction between hydrogen and metals. [52][53][54] However, these materials have faced many challenges, such as materials synthesis, system cost, durability/operability, charging/discharging rate, system life-cycle, and lack of understanding of hydrogen adsorption/desorption kinetics to use hydrogen energy storage technologies in mobile transportation and power station applications. Fig.…”

Review of thermal management technology for metal hydride reaction beds

“…10c), which decreased the time needed for hydrogen absorption by almost 40%. Larpruenrudee et al 126 and Eisapour et al 127 proposed a semi-cylindrical coil heat exchanger (SCHE) and a multi-zone configuration in the MHB, respectively, where significantly lower MHB temperatures and faster absorption rate can be observed. Lewis et al 128 reported the use of the MHR with an embossed plate heat exchanger (EPHX) and created four different flow field designs: parallel, pin-type, vertical serpentine, and horizontal serpentine, among which the serpentine flow-field EPHX presented better heat transfer and faster hydrogen storage ability.…”