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Metal hydride (MH) hydrogen storage needs an external heat source to release the stored hydrogen. To enhance the thermal performance of MHs, the incorporation of phase change materials (PCM) is a way to preserve reaction heat. This work proposes a new MH-PCM compact disk configuration (i.e., a truncated conical MH bed surrounded by a PCM ring). An optimization method is developed to find the optimal geometrical parameters of the MH truncated cone, which is then compared to a basic configuration (i.e., a cylindrical MH surrounded by a PCM ring). Moreover, a mathematical model is developed and used to optimize the heat transfer in a stack of MH-PCM disks. The optimum geometric parameters found (bottom radius of 0.2, top radius of 0.75 and tilt angle of 58.24) allow the truncated conical MH bed to reach a faster heat transfer rate and a large surface area of higher heat exchange. Compared to a cylindrical configuration, the optimized truncated cone shape enhances the heat transfer rate and the reaction rate in the MH bed by 37.68%. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a numerical study of a new high‐temperature metal hydride bed configuration integrating a phase change material (PCM) and equipped with heat pipes. The first half of the heat pipe is incorporated into the metal hydride (MH) tank and the second into the PCM domain to enhance heat transfer between two domains. A parametric study of different thermophysical and geometrical parameters of both media (MH and PCM) was carried out. In the simulations, the thermal conductivities of the MH and the PCM, the convective heat transfer coefficient, the melting temperature, and the number of heat pipes were investigated to evaluate their effects on the kinetics of absorption and melting of the PCM. Numerical results showed that the reactor performance improved upon increasing the PCM thermal conductivity, the convective heat transfer coefficient and the number of heat pipes and also by considering an optimal melting temperature, which ensures good hydrogen storage capacity in a minimum loading time. [ABSTRACT FROM AUTHOR]

Summary: This article presents a numerical investigation of two discharging procedures of a metal hydride‐hydrogen storage tank (MH‐HST). The former is categorized as "simultaneous procedure" as the heating of the MH‐HST and the discharging of hydrogen from the same start simultaneously. The latter is categorized as "separated procedure" as the heating of the MH‐HST was carried out initially and the discharging of hydrogen from the same began only when the desired desorption temperature is attained. To the best of authors' knowledge, the separated procedure is simulated and compared for the first time with the simultaneous case. For the two procedures, the discharging process was carried out in two ways, that is, at constant and variable applied pressure. A computational model governing heat and mass transfer within the MH‐HST was developed and successfully validated with experimental data. The simulation results ascertain that the simultaneous procedure is faster than the separated procedure. For example, with a desorption pressure of 0.1 bar and a heating fluid temperature of 353 K, the "simultaneous procedure" provides a reduction of the discharging time by 57% in comparison with the "separated procedure." [ABSTRACT FROM AUTHOR]

In this paper, coupled heat and mass transfer during the desorption process of a metal-hydrogen reactor (LaNi5-H2) is numerically investigated. To predict the dynamic behavior of this reactor, a new algorithm based on the lattice Boltzmann method (LBM) is proposed as a potential solver. Based on this algorithm, a computer code is developed using fortran 90. This algorithm is validated successfully by comparison with experimental data reported in the literature and results obtained by finite volume method (FVM). Using the developed code, the time-space evolutions of the temperature and the hydride density within the reactor are presented. In addition, the effect of some parameters (applied pressure, heating temperature, and overall heat transfer coefficient) on the dynamic behavior of the reactor is evaluated. Compared to the FVM, the proposed algorithm presents simple implementation on a computer and with reduced CPU time. [ABSTRACT FROM AUTHOR]