Mathematical modelling of hydrogen storage in a LaNi5 hydride bed

WOS: 000185111800004This paper presents a numerical investigation of hydrogen storage in a metal hydrid bed. For this Purpose, a two-dimensional mathematical model which considers complex heat and mass transfer and fluid flow during the hydriding process is accomplished ill this study. The coupled differential equations are solved with numerical method based on integrations Of equation over finite control volumes. The driving force for fluid flow is considered to be pressure difference due to the temperature distribution in the system. It is found that fluid flow enhances the local hydriding rate in the system by driving the hot fluid to the colder regions. The numerical results were found to agree satisfactorily with the experimental data available in the literature. Copyright (C) 2003 John Wiley Sons, Ltd

Numerical investigation of heat and mass transfer in a metal hydride bed

WOS: 000189100600015This paper presents a mathematical model for hydrogen storage in a metal hydride bed. For this purpose, a two-dimensional mathematical model which considers complex heat and mass transfer during the hydriding process is developed. The coupled differential equations are solved with a numerical method based on integrations of governing equation over finite control volumes. The driving force is considered to be pressure difference because of the temperature distribution in the system. The numerical results showed that the hydriding performance depends on the temperature distribution in the hydride bed. Fluid flow enhances the hydriding rate in the system by driving the hot fluid to the colder regions. The numerical results were found to agree satisfactorily with the experimental data available in the literature. (C) 2003 Elsevier Inc. All rights reserved

A two phase model for electrochemical systems

NATO Advanced Research Workshop on Fuel Cell Technologies -- JUN 06-10, 2004 -- Kiev, UKRAINEWOS: 000235157200030Two phase flow is encountered in many electrochemical systems and play vital role on system efficiency, species transport, velocity distribution etc. A two phase flow model which accounts specific nature of liquid and gaseous phase is developed. The model applied to water electrolysis in an electrochemical cell. Transport equations are solved numerically for both phases with allowance for inter - phase mass and momentum Exchange. Liquid and gaseous phase distributions velocities, current density distribution are calculated under various working conditions. It is found that gas layer accumulation on the electrode surface decreases the active reaction area and adversely affects the reaction rate.NATO, European Off Aerosp Res & Dev, N Carolina A & T State Univ, Ctr Adv Mat & Smart Structures, Connecticut Global Fuel Cell Ctr, Univ Connecticut, Frantcevych Inst Problem Mat Sci, Zirconia Ukraine Lt

Experimental and theoretical study of metal-hydride reactors

NATO Advanced Research Workshop on Fuel Cell Technologies -- JUN 06-10, 2004 -- Kiev, UKRAINEWOS: 000235157200022Hydrogen absorption in LaNi5-H-2 reactor is experimentally and theoretically investigated. Two different reactors were designed and hydrogen gas was charged at constant temperature at constant pressure. Temperature changes in the tanks during the hydrogen charge were measured at several locations and readings of the data were continued until the temperature has stabilized. In the theoretical program, a two dimensional mathematical model, which considers complex heat and mass transfer during this process is developed and numerically solved. The numerical results are compared with the measured data to validate the mathematical model. A reasonable agreement between the numerical results and experimental data is obtained.NATO, European Off Aerosp Res & Dev, N Carolina A & T State Univ, Ctr Adv Mat & Smart Structures, Connecticut Global Fuel Cell Ctr, Univ Connecticut, Frantcevych Inst Problem Mat Sci, Zirconia Ukraine Lt

Hydrogen as burner fuel: modelling of hydrogen-hydrocarbon composite fuel combustion and NOx formation in a small burner

The objective of this work is to investigate numerically the turbulent non-premixed hydrogen (H-2) and hydrogen-hydrocarbon flames in a small burner. Numerical studies using Fluent code were carried out for air-staged and non-staged cases. The effects of fuel composition from pure hydrogen to natural gas (100% H-2, 70% H-2 + 30% CH4, 10% H-2 + 90% CH4, and 100% CH4) were also investigated. The predictions are validated and compared against the experimental results previously obtained and results from the literature. Turbulent diffusion flames are investigated numerically using a finite volume method for the solution of the conservation equations and reaction equations governing the problem. Although, three different turbulence models were tested, the standard k-epsilon model was used for the modelling of the turbulence phenomena in the burner. The temperature and major pollutant concentrations (CO and NOx) distributions are in good agreement with the existing experimental results. Air staging causes rich and lean combustion regions thus lower NOx emissions through the combustor exit. Blending hydrogen with methane causes considerable reduction in temperature levels and thus NO emissions. Increasing the mixture ratio from stoichiometric to leaner mixtures also decreases the temperature and thus NO emissions. Hydrogen may be considered a good alternative fuel for burners, as its use reduces the emission of pollutants; and as it is a renewable synthetic fuel. Copyright (c) 2005 John Wiley & Sons, Ltd

Internal combustion engines fueled by natural gas - hydrogen mixtures

In this study, a survey of research papers on utilization of natural gas-hydrogen mixtures in internal combustion engines is carried out. In general, HC, CO2, and CO emissions decrease with increasing H-2, but NOx emissions generally increase. If a catalytic converter is used, NOx emission values can be decreased to extremely low levels. Consequently, equivalence zero emission vehicles (EZEV) standards may be reached. Efficiency values vary with H-2 amount, spark timing, compression ratio, equivalence ratio, etc. Under certain conditions, efficiency values can be increased. In terms of BSFC, emissions and BTE, a mixture of low hydrogen percentage is suitable for using. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved

Experimental and theoretical analysis of hydrogen absorption in LaNi5-H-2 reactors

WOS: 000233293500010Hydrogen absorption in two LaNi5-H2 reactors is experimentally and theoretically investigated. In the experimental program, two tanks are filled with LaNi5 alloy and hydrogen is charged with a constant pressure. The temperature changes in the tanks are measured at several locations and recorded in a computer. Hydriding process is identified from measured temperature histories. In the theoretical program, a two-dimensional mathematical model, which considers complex heat and mass transfer and fluid flow is developed and numerically solved. The numerical results are compared with the measured data to validate the mathematical model. A reasonable agreement between the numerical results and experimental data is obtained. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved