1,720,986 research outputs found
Development of a new approach for the kinetic modeling of the lithium reactive hydride composite (Li-RHC) for hydrogen storage under desorption conditions
No full textAmong some promising candidates for high-capacity energy and hydrogen storage is the Lithium-Boron Reactive Hydride Composite System (Li-RHC: 2 LiH + MgB2/2 LiBH4 + MgH2). This system desorbs hydrogen only at relatively high temperatures and presents a two-step series of reactions occurring in different time scales: first, MgH2 desorbs, followed by LiBH4. Hitherto, the dehydrogenation kinetic behavior of such a system has been described for different temperatures at specific values of operative pressure. However, a comprehensive model representing its dehydrogenation kinetic behavior under different operative conditions has not yet been developed. Herein, the separable variable method is applied to develop a comprehensive kinetic model, including the two-step dehydrogenation series reaction. The MgH2 decomposition is described with the one-dimensional interface-controlled reaction rate Johnson-Mehl-Avrami-Erofeyev-Kholmogorov (JMAEK) with a (Pequilibrium/Poperative) pressure functionality and an Arrhenius temperature dependence activation energy of 63 ± 3 kJ/mol H2. The LiBH4 decomposition is modeled applying the autocatalytic Prout-Tompkins model. A novel approach to describe the Prout-Tompkins t0 parameter as a function of the operative temperature and pressure model is proposed. This second reaction step presented a (Pequilibrium – Poperative/Pequilibrium)2 pressure dependence and an Arrhenius temperature dependence with activation energy 94 ± 13 kJ/mol H2. The proposed approach is experimentally and computationally validated, successfully describing the decomposition kinetic behavior of MgH2 and LiBH4 under three-phase gas, liquid and solid environment and shows good agreement between experimental and modeled curves
Modeling and Parameterization of a PEM Fuel Cell Stack for a System Integration Into a Metal Hydride Based Hydrogen Storage System
No full textPower systems using renewable energy sources have emerged as a sustainable solution for decarbonizing the energy sector. Implementing such systems requires integrating them with an efficient storage medium to improve their reliability and flexibility. This work explores the modeling and parameterization of a fuel cell system, with the purpose of coupling it with a metal hydride-based hydrogen storage reservoir. An electrical and thermal 0D simulation model for a 1.6 kW air-cooled proton exchange fuel cell stack is developed to investigate its performance, heat transfer and temperature development. The model validation and simulation are done by testing it with four different steady-state power demand scenarios. Experimental results show an efficient thermal coupling between the fuel cell stack and the metal-hydride system. Simulations and experimental results show an excellent agreement. The developed modeling approach is also appliccable to the design of different gas-to-power configurations and sizes, for the design of fuel cell-metal hydride storage systems
Changing the dehydrogenation pathway of LiBH4-MgH2via nanosized lithiated TiO2
Get PDFNanosized lithiated titanium oxide (LixTiO2) noticeably improves the kinetic behaviour of 2LiBH4 + MgH2. The presence of LixTiO2 reduces the time required for the first dehydrogenation by suppressing the intermediate reaction to Li2B12H12, leading to direct MgB2 formation.Fil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Karimi, F.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Santoru, A.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Pistidda, C.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Klassen, T.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Bellosta von Colbe, J. M.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Dornheim, M.. Helmholtz-zentrum Geesthacht; Alemani
A Novel Emergency Gas-to-Power System Based on an Efficient and Long-Lasting Solid-State Hydride Storage System: Modeling and Experimental Validation
Get PDFIn this paper, a gas-to-power (GtoP) system for power outages is digitally modeled and experimentally developed. The design includes a solid-state hydrogen storage system composed of TiFeMn as a hydride forming alloy (6.7 kg of alloy in five tanks) and an air-cooled fuel cell (maximum power: 1.6 kW). The hydrogen storage system is charged under room temperature and 40 bar of hydrogen pressure, reaching about 110 g of hydrogen capacity. In an emergency use case of the system, hydrogen is supplied to the fuel cell, and the waste heat coming from the exhaust air of the fuel cell is used for the endothermic dehydrogenation reaction of the metal hydride. This GtoP system demonstrates fast, stable, and reliable responses, providing from 149 W to 596 W under different constant as well as dynamic conditions. A comprehensive and novel simulation approach based on a network model is also applied. The developed model is validated under static and dynamic power load scenarios, demonstrating excellent agreement with the experimental results
Compaction pressure influence on material properties and sorption behaviour of LiBH4-MgH2 composite
Get PDFAmong different Reactive Hydride Composites (RHCs), the combination of LiBH4 and MgH2 is a promising one for hydrogen storage, providing a high reversible storage capacity. During desorption of both LiBH4 and MgH2, the formation of MgB2 lowers the overall reaction enthalpy. In this work, the material was compacted to pellets for further improvement of the volumetric hydrogen capacity. The influence of compaction pressure on the apparent density, thermal conductivity and sorption behaviour for the Li-based RHC during cycling was investigated for the first time. Although LiBH4 melts during cycling, decrepitation or disaggregation of the pellets is not observed for any of the investigated compaction pressures. However, a strong influence of the compaction pressure on the apparent hydrogen storage capacity is detected. The influence on the reaction kinetics is rather low. To provide explanations for the observed correlations, SEM analysis before and after each sorption step was performed for different compaction pressures. Thus, the low hydrogen sorption in the first cycles and the continuously improving sorption for low pressure compacted pellets with cycling may be explained by some surface observations, along with the form stability of the pellets
Hydrogen - Heat Storage System Based on Metal Hydride and Phase Change Material
No full textThe goal of the HyCARE project is to store renewable energy using hydrogen as energy carrier by means of a metal hydride (MH), coupling a phase change material (PCM) for the heat management. The feasibility of the concept has been investigated thanks to the realization of a prototype including a MH-tank and a PCM module storing about 0.5 kg of H2. The innovation of the use of PCM in the heat management of MH system is linked to the reduction of external heat intake, and during the tests the optimal conditions of hydrogen flow, thermal fluid flow, starting temperature have been evaluated, in order to minimize the external power contribution. It was highlighted that, in the optimal conditions, the PCM was able to collect and supply the heat generated/required by the MH storage system, with the external power source contributing only to compensate the heat losses
HYDRIDE4MOBILITY: An EU HORIZON 2020 project on hydrogen powered fuel cell utility vehicles using metal hydrides in hydrogen storage and refuelling systems
Get PDFThe goal of the EU Horizon 2020 RISE project 778307 “Hydrogen fuelled utility vehicles and their support systems utilising metal hydrides” (HYDRIDE4MOBILITY), is in addressing critical issues towards a commercial implementation of hydrogen powered forklifts using metal hydride (MH) based hydrogen storage and PEM fuel cells, together with the systems for their refuelling at industrial customers facilities. For these applications, high specific weight of the metallic hydrides has an added value, as it allows counterbalancing of a vehicle with no extra cost. Improving the rates of H2 charge/discharge in MH on the materials and system level, simplification of the design and reducing the system cost, together with improvement of the efficiency of system “MH store-FC”, is in the focus of this work as a joint effort of consortium uniting academic teams and industrial partners from two EU and associated countries Member States (Norway, Germany, Croatia), and two partner countries (South Africa and Indonesia). The work within the project is focused on the validation of various efficient and cost-competitive solutions including (i) advanced MH materials for hydrogen storage and compression, (ii) advanced MH containers characterised by improved charge-discharge dynamic performance and ability to be mass produced, (iii) integrated hydrogen storage and compression/refuelling systems which are developed and tested together with PEM fuel cells during the collaborative efforts of the consortium. This article gives an overview of HYDRIDE4MOBILITY project focused on the results generated during its first phase (2017–2019)
Modeling the kinetic behavior of the Li-RHC system for energy-hydrogen storage: (I) absorption
Get PDFThe Lithium–Boron Reactive Hydride Composite System (Li-RHC) (2 LiH + MgB2/2 LiBH4 + MgH2) is a high-temperature hydrogen storage material suitable for energy storage applications. Herein, a comprehensive gas-solid kinetic model for hydrogenation is developed. Based on thermodynamic measurements under absorption conditions, the system's enthalpy ΔH and entropy ΔS are determined to amount to −34 ± 2 kJ∙mol H2−1 and −70 ± 3 J∙K−1∙mol H2−1, respectively. Based on the thermodynamic behavior assessment, the kinetic measurements' conditions are set in the range between 325 °C and 412 °C, as well as between 15 bar and 50 bar. The kinetic analysis shows that the hydrogenation rate-limiting-step is related to a one-dimensional interface-controlled reaction with a driving-force-corrected apparent activation energy of 146 ± 3 kJ∙mol H2−1. Applying the kinetic model, the dependence of the reaction rate constant as a function of pressure and temperature is calculated, allowing the design of optimized hydrogen/energy storage vessels via finite element method (FEM) simulations
Metal hydrides for concentrating solar thermal power energy storage
No full textThe development of alternative methods for thermal energy storage is important for improving the efficiency and decreasing the cost of concentrating solar thermal power. We focus on the underlying technology that allows metal hydrides to function as thermal energy storage (TES) systems and highlight the current state-of-the-art materials that can operate at temperatures as low as room temperature and as high as 1100 °C. The potential of metal hydrides for thermal storage is explored, while current knowledge gaps about hydride properties, such as hydride thermodynamics, intrinsic kinetics and cyclic stability, are identified. The engineering challenges associated with utilising metal hydrides for high-temperature TES are also addressed
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