THE EFFECT OF IMPURITIES ON POLYMER ELECTROLYTE MEMBRANE ELECTROLYZERS FOR IN-SITU ASTEROID HYDROGEN GENERATION by Christopher Kitson A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Honors Bachelor of Mechanical Engineering with Distinction Spring 2018 © 2018 Christopher Kitson All Rights Reserved THE EFFECT OF IMPURITIES ON POLYMER ELECTROLYTE MEMBRANE ELECTROLYZERS FOR IN-SITU ASTEROID HYDROGEN GENERATION by Christopher Kitson Approved: __________________________________________________________ Ajay Prasad, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: __________________________________________________________ Valery Roy, Ph.D. Committee member from the Department of Mechanical Engineering Approved: __________________________________________________________ Sue McNeil, Ph.D. Committee member from the Board of Senior Thesis Readers Approved: __________________________________________________________ Paul Laux, Ph.D. Director, University Honors Program ACKNOWLEDGMENTS Thank you to Dr. Ajay Prasad, Alumni Distinguished Professor and Chair of the Department of Mechanical Engineering, for all of your guidance and advice in conducting this research. Also, thank you for your help contacting colleagues, and for the opportunity to conduct research in the Center for Fuel Cells and Batteries (CFCB). Thank you to Ashish Chouhan, doctoral candidate in CFCB, for helping me troubleshoot, float ideas, and for lending a hand whenever I needed help. Thank you Sai Yellamilli, doctoral candidate in CFCB, for help tidying up the lab workspaces and for your assistance operating the Arbin Fuel Cell Test Stand. Thank you to Gabe Brown, undergraduate mechanical engineering student, for your assistance this past winter in many various capacities on my research. Thank you to Adam Kinzey, for the DC power supply and for the pipe fittings. Thank you to Alfred Lance and Brian Brant, for helping to machine anode parts. Thank you to Dr. Liang Wang, postdoc formerly of CFCB, for teaching me the ropes on how to use fuel cells, and for all your help in the lab these past three years. Thank you to Dr. Sue McNeil, Professor within and Chair of the Department of Civil & Environmental Engineering, for organizing the interim thesis presentations, providing feedback, serving on my thesis committee, and helping proofread. Thank you to Dr. Valery Roy, Professor in the Department of Mechanical Engineering, for serving on my thesis committee and helping proofread my thesis. Lastly, thank you to the Federal Transit Administration for funding this research in part with the University of Delaware Fuel Cell Bus Grant. iii TABLE OF CONTENTS LIST OF TABLES ...................................................................................................... viii LIST OF FIGURES ....................................................................................................... ix LIST OF EQUATIONS ................................................................................................ xv LIST OF ABBREVIATIONS ..................................................................................... xvi ABSTRACT ................................................................................................................ xix CHAPTERS 1 BACKGROUND ................................................................................................ 1 1.1 THESIS OVERVIEW ............................................................................... 1 1.2 ELECTROLYZERS .................................................................................. 2 1.2.1 CELL CHEMISTRY ..................................................................... 3 1.2.2 ANODE ......................................................................................... 4 1.2.3 CATHODE .................................................................................... 5 1.2.4 MEMBRANE ................................................................................ 5 1.2.5 MEMBRANE ELECTRODE ASSEMBLY ................................. 5 1.3 ROCKET PROPULSION ......................................................................... 7 1.3.1 PROPELLANTS ........................................................................... 8 1.3.2 ROCKET PHYSICS .................................................................... 10 1.3.3 PROPULSION METHODS ........................................................ 12 1.3.4 CHOOSING PROPELLANTS .................................................... 14 1.4 ORBITAL MECHANICS ....................................................................... 16 1.4.1 ORBITS ....................................................................................... 16 1.4.2 CHANGING ORBITS ................................................................. 19 1.4.3 LAGRANGE POINTS ................................................................ 21 1.4.4 DEEP SPACE OPERATION ...................................................... 23 1.4.5 DEEP SPACE MISSIONS .......................................................... 24 1.4.6 REUSABLE ROCKETS ............................................................. 26 1.5 IN-SITU RESOURCE UTILIZATION .................................................. 27 1.5.1 TECHNOLOGY READINESS LEVELS ................................... 28 iv 1.5.2 NASA MARCO POLO DEMONSTRATOR ............................. 29 1.5.3 ORBITAL MECHANICS WITH IRSU ...................................... 31 1.5.4 ‘EARTH RELIANT’ TO ‘EARTH INDEPENDENT’ ............... 31 1.6 TRANSPORTATION NETWORKS ...................................................... 33 1.6.1 GRAVITATIONAL ASSISTS .................................................... 34 1.6.2 SPACETIME TUBES ................................................................. 35 1.6.3 STEPPING STONES .................................................................. 37 2 MOTIVATION ................................................................................................. 39 2.1 WATER IN SPACE ................................................................................ 39 2.1.1 LIFE SUPPORT .......................................................................... 39 2.1.2 PROPELLANT PRODUCTION ................................................. 41 2.1.3 ECONOMIC VALUE ................................................................. 42 2.2 DETERMINING ASTEROID COMPOSITION .................................... 44 2.2.1 SPECTROSCOPY ....................................................................... 44 2.2.2 METEORITE SAMPLES ........................................................... 46 2.2.3 FLYBY AND OBSERVATION MISSIONS ............................. 47 2.2.4 SAMPLE MISSIONS .................................................................. 49 2.3 CARBONACEOUS CHONDRITE ASTEROIDS ................................. 50 2.3.1 RELATIVE COMMONALITY .................................................. 51 2.3.2 CHEMICAL COMPOSITION .................................................... 51 2.4 ASTEROID MINING ............................................................................. 52 2.4.1 SYSTEM ARCHITECTURES .................................................... 53 2.4.2 PROCESSING FRAMEWORKS ............................................... 54 2.5 SABATIER PROCESS ........................................................................... 56 2.5.1 DEEP CRYOGENIC METHALOX ........................................... 57 2.5.2 SABATIER REACTION ............................................................ 57 2.5.3 PRECURSOR ELECTROLYSIS ................................................ 58 2.6 IMPURITY SELECTION ....................................................................... 58 2.6.1 IRON(II) SULFATE HEPTAHYDRATE .................................. 59 2.6.2 AMMONIUM IRON (III) SULFATE DODECAHYDRATE .... 60 v 2.6.3 UREA .......................................................................................... 60 3 ELECTROLYZER DESIGN ............................................................................ 61 3.1 DESIGN OVERVIEW ............................................................................ 61 3.2 BALANCE OF PLANT .......................................................................... 62 3.2.1 WATER TANK ........................................................................... 63 3.2.2 FEEDWATER INPUT ................................................................ 64 3.2.3 HEATER SYSTEM ..................................................................... 65 3.2.4 DATA ACQUISITION SYSTEM .............................................. 66 3.2.5 UMBILICALS ............................................................................. 66 3.3 ELECTROLYZER CELL STACK ......................................................... 68 3.4 MEMBRANE ELECTRODE ASSEMBLY ........................................... 70 3.4.1 CATHODE SIDE ........................................................................ 72 3.4.2 ANODE SIDE ............................................................................. 73 3.4.3 PROTON EXCHANGE MEMBRANE ...................................... 75 3.5 MAJOR DESIGN CONFIGURATIONS ................................................ 77 3.5.1 COMPONENT-WISE TESTING ............................................... 77 3.5.2 ANODE EXPERIMENTATION SETUP ................................... 78 3.5.3 ARBIN HOOKUP CONFIGURATION ..................................... 80 4 METHODS ......................................................................................................