H2 Technology Consulting, LLC [email protected] tel: (510) 468-7515 Recommended Best Practices for Characterizing Engineering Properties of Hydrogen Storage Materials Karl J. Gross, H2 Technology Consulting LLC Bruce Hardy, of Savannah River National Laboratory We gratefully acknowledge assistance and financial support from the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Hydrogen Storage Program. National Renewable Energy Laboratory Contract No. 147388 Contract Technical Monitor: Dr. Philip Parilla Page 1 of 282 Recommended Best Practices for Characterizing Engineering Properties of Hydrogen Storage Materials. V150: February 4, 2013 Table of Contents LIST OF FIGURES ............................................................................................................................................. 5 LIST OF TABLES ............................................................................................................................................... 9 RECOMMENDED READING ...........................................................................................................................10 1 HYDROGEN STORAGE ...................................................................................................................................10 2 HYDRIDES ..................................................................................................................................................10 3 METAL HYDRIDES .......................................................................................................................................10 4 OFF-BOARD REGENERABLE HYDROGEN STORAGE MATERIALS ..............................................................................10 5 PHYSISORPTION STORAGE .............................................................................................................................11 6 THERMODYNAMICS .....................................................................................................................................11 7 ENGINEERING THERMAL PROPERTIES ..............................................................................................................11 SECTION 6: MEASUREMENTS OF ENGINEERING THERMAL PROPERTIES OF HYDROGEN STORAGE MATERIALS ....................................................................................................................................................12 1 INTRODUCTION ...........................................................................................................................................12 HEAT TRANSFER ............................................................................................................................................14 THERMAL CONVECTION ................................................................................................................................15 THERMAL RADIATION ...................................................................................................................................15 THERMAL CONDUCTIVITY .............................................................................................................................15 1 THERMAL CONDUCTIVITY – IMPORTANCE ........................................................................................................15 2 THEORY ....................................................................................................................................................16 2.1 Thermal Conductivity of Solids .......................................................................................................16 2.2 Thermal Conductivity of Liquids and Gases ....................................................................................22 2.3 Thermal Conductivity of Porous Materials .....................................................................................23 2.4 Thermal Conductivity of Packed Particle Beds ...............................................................................25 3 THERMAL CONTACT RESISTANCE ....................................................................................................................28 4 MODELING OF THERMAL CONDUCTIVITY .........................................................................................................30 5 THERMAL CONDUCTIVITY MEASUREMENT METHODS .........................................................................................35 5.1 Standards .......................................................................................................................................35 5.2 Introduction to Measurement Methods .........................................................................................37 5.2.1 Considerations for which measurement method to use? ...................................................................... 39 5.2.1 Common Thermal Properties Measurement Q&As ............................................................................... 46 5.2.2 In situ Measurements ............................................................................................................................ 49 5.2.3 Steady-State vs. Transient Techniques ................................................................................................... 50 5.2.1 Example of One Common Measurement Approach for Hydrogen Storage Materials ........................... 51 5.3 Heat Flux Measurement Methods ..................................................................................................52 5.1 Axial Flow Methods ........................................................................................................................52 5.1.1 Direct Power Measurement ................................................................................................................... 54 5.1.1 Comparative Thermal Conductivity Methods ........................................................................................ 55 5.1.2 Boil-off Calorimetry Method .................................................................................................................. 56 5.2 Guarded or unguarded heat flow meter method (ASTM C518, E1530). ........................................56 5.3 Guarded Hot Plate Method (ASTM C 177) ....................................................................................57 5.4 Radial Heat Flow Method ..............................................................................................................62 5.5 Concentric Cylinders Method .........................................................................................................64 5.6 Concentric Spheres Method ...........................................................................................................70 5.7 Divided Bar Method (ASTM E1225-87) ..........................................................................................71 5.8 Guarded-Comparative-Longitudinal Heat Flow Method (ASTM E1225 – 09) ................................73 5.9 Thermal Probe Method (ASTM D 5334) .........................................................................................77 Page 2 of 282 Recommended Best Practices for Characterizing Engineering Properties of Hydrogen Storage Materials. V150: February 4, 2013 Table of Contents 5.10 Transient Plane Source (TPS) Method ..........................................................................................79 5.11 Hot Wire Method for Solid Samples (ASTM C1113) .....................................................................88 5.12 Hot-Wire Method (ASTM C1113) for Gases and Liquids ..............................................................93 5.13 Flash Method (ASTM 1461) ..........................................................................................................94 6 EXAMPLES OF THERMAL CONDUCTIVITY MEASUREMENTS OF HYDROGEN STORAGE MATERIALS AND STORAGE SYSTEM DESIGN ......................................................................................................................................................102 6.1 On-board Reversible Hydride Storage Systems ............................................................................102 6.1.1 Introduction to Thermal Properties of Hydrides and Impact on Storage System Performance ........... 102 6.1.2 Example: Tests of System with Basic Heat Transfer: ............................................................................ 108 6.1.1 Example: Testing and Modeling of Advanced Heat Transfer System: .................................................. 111 6.1.1 Example: Thermal Conductivity Measurements of MgH2 .................................................................... 116 6.1.2 Example: In-Situ Thermal Probe Measurements of Alanates ............................................................... 118 6.1.1 Example: In-Situ TPS Measurements of Hydrides ................................................................................ 128 6.2 Thermal Conductivity of On-Board Rechargeable Physisorption Materials .................................142 6.1 Thermal Conductivity of Off-board Regenerable Hydride Materials ............................................147 6.1.1 Example: Ammonia borane .................................................................................................................. 147 7 EXPERIMENTAL AND ANALYSIS CONSIDERATIONS .............................................................................................148 7.1 Form of Sample to be Measured ..................................................................................................148