Analysis of desorption behavior in metal-based hydrogen storage systems through pilot-scale experimentation and numerical simulation

학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2017. 2. 이경우.Hydrogen storage alloys that form metal hydrides (MH) are a promising type of material in hydrogen storage applications, allowing for low-pressure, high-density hydrogen storage. However, while many studies are being performed on enhancing the hydrogen storage properties of such alloys, there has been little research on large-scale storage vessels which make use of the alloys. In particular, large-scale, high-density storage devices must make allowances for the temperature variations caused by the heat of reaction between hydrogen and hydriding alloys, which may impact the storage characteristics. In this study, we propose a numerical model for the design and evaluation of hydrogen storage devices using hydriding alloys. Hydrogen desorption reaction behavior for an alloy is measured in terms of temperature, reaction rate and hydrogen concentration variation over time These data are then analyzed to yield a behavioral correlation which is used as the basis for a comprehensive simulation model of the alloy system. While a solid solution TiCrV-Fe alloy is used in the present study to gather these experimental data, the experimental procedure may be applied in an identical way to any metal hydride material subject to analysis. Calculated results of the model are found to be in good agreement with experimentally measured data. The accuracy of the model makes it useful in predicting the desorption behavior for a single system under multiple operating conditions. It can also be employed to evaluate multiple systems that satisfy a single set of given operating conditions. Given its accuracy and versatility, the model is expected to be highly useful in analyses of multiple system geometries, scales, and metal hydride alloy materials.Chapter 1. Introduction 1 1.1 The Hydrogen Economy 1 1.2 Hydrogen storage methods 2 1.2.1 Physical storage of hydrogen 5 1.2.2 Metal hydride (MH) materials 10 1.3 Previous studies 16 1.3.1 Hydrogen storage alloy development 17 1.3.2 MH-based hydrogen storage systems 22 1.4 Research goals 27 Chapter 2. Numerical Model Development 29 2.1 Calculation algorithm 29 2.1.1 Rate factor k 31 2.1.2 Order of calculation 34 2.2 Material properties 36 2.3 Numerical calculation theory 39 2.3.1 Flow 39 2.3.2 Heat transfer 44 2.3.3 Boundary conditions 46 Chapter 3. Experimentation 48 3.1 TiCrV-Fe material 48 3.2 Materials characterization 52 3.3 Experimental verification of model 55 Chapter 4. Results and Discussion 60 4.1 Numerical characterization of material 60 4.1.1 Temperature and reaction rate 60 4.1.2 The relationship between R, T and C 64 4.2 Experimental vs. calculated results 74 Chapter 5. Model Applications 81 5.1 Desorption behavior for a MH hydrogen storage vessel 83 5.1.1 Analysis of thermal behavior 83 5.1.2 Desorption under multiple operating conditions 85 5.2 Analysis of multiple vessel designs for engineering application 88 Chapter 6. Conclusions 103 References 105 Korean abstract 116Docto