Intro
Foreword by Goodarz Ahmadi and Takashi Hibiki
Foreword by Hongguang Jin
Acknowledgments
Contents
1 Introduction
1.1 High-Temperature Gas-Cooled Reactor (HTGR)
1.1.1 Classification and Brief History
1.1.2 Main Features and Advantages
1.2 Pebble Bed Type HTGR in Tsinghua University
1.2.1 Competative Technical Routes
1.2.2 Heat Transfer Investigations
1.3 Pebble Flows
1.3.1 Discharging/recirculating Granular Flow
1.3.2 Very Slow Pebble Flow in HTGR
1.3.3 Pebble Flow Intermittency
1.3.4 Importance of Flow Uniformity

1.3.5 Optimization of Pebble Flow Design
1.3.6 Review of State-of-the-Art Work
1.4 Pebble Bed Heat Transfer
1.4.1 Gas-Pebble Heat Transfer
1.4.2 Pebble Thermal Radiation
1.4.3 Effective Thermal Diffusivity and Conductivity
1.5 Summary
References
2 Experiments in Pebble Flows
2.1 Experimental Test Facility
2.2 Phenomenological Methods
2.2.1 Drainage Pebble Experiment
2.2.2 Central Area Method
2.2.3 Side Area Method
2.2.4 Pre-filled Stripes Method
2.2.5 Pre-filled Core Method
2.3 Pebble Flow in Two-Region Beds

2.3.1 Formation of Two-Region Arrangements
2.3.2 Mixing Zone and Stagnant Zone
2.3.3 Motion of Pebbles
2.3.4 Equilibrium Conditions and Flow Characteristics
2.4 Pebble Flow Mechanism Analysis
2.4.1 Quasi-Static Pebble Flow
2.4.2 Distribution of Contact Force
2.4.3 Basic Physics of Quasi-Static Flow
2.4.4 Short Summary
2.5 Particle Velocimetry Measurements
2.5.1 Measurement Techniques
2.5.2 Image Processing
2.5.3 Flow Correlation and Intermittency
2.5.4 Pebble Arch Formation
2.6 Summary
References
3 Experiments in Pebble Bed Heat Transfer

3.1 Introduction
3.2 Experimental Facility and Methodology
3.2.1 Configuration of Heat Test Facility
3.2.2 Data Processing Algorithm
3.2.3 Preliminary Tests in Vacuum
3.2.4 Short Summary
3.3 Effective Thermal Diffusivity and Conductivity
3.3.1 Experimental Processes
3.3.2 Methodology Description
3.3.3 Quadratic Polynomial Function Results
3.3.4 Improved Method to Reduce Errors
3.3.5 Uncertainty Analysis
3.3.6 Short Summary
3.4 Summary
References
4 Numerical Methods and Simulation for Pebble Flows
4.1 Discrete Element Methods

4.2 Gravity-Driven Flow Regime Characterization
4.2.1 Flow Behavior Characteristics
4.2.2 Kinetic Versus Kinematic
4.2.3 Energy Span Versus Standard Deviation
4.2.4 Recirculation Rates and Times
4.3 Three-Dimensional Pebble Flow
4.3.1 Voidage Distributions in HTR-10
4.3.2 3D Pebble Flow in HTR-PM
4.4 Summary
References
5 Numerical Models for Pebble-Bed Heat Transfer
5.1 Introduction
5.2 Continuum Modeling of Pebble Radiation
5.2.1 Uniform Effective Thermal Conductivity (uETC)
5.2.2 Approximation Function Method
5.2.3 Short Summary