Permeation barrier for lightweight liquid hydrogen tanks [Elektronische Ressource] / vorgelegt von Daniel Schultheiß

Informations

• Publié par: universitat_augsburg
• Publié le: 01 janvier 2007
• Nombre de lectures: 37
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Permeation Barrier for Lightweight
Liquid Hydrogen Tanks
Dissertation zur Erlangung des Doktorgrades
der Mathematisch-Naturwissenschaftlichen Fakult¨at
der Universitat Augsburg¨
vorgelegt von
Daniel Schultheiß
16.April 2007
OPUS Augsburg
der Online-Publikationsserver der Universit¨at AugsburgErstgutachter: Prof. Dr. Siegfried R. Horn
Zweitgutachter: Prof. Dr. Ferdinand Haider
Tag der mu¨ndlichen Pru¨fung: 06.Juni 2007Contents
Table of Contents i
Notation iii
1 Introduction 1
2 Permeation in Metals and Polymers 7
2.1 Structure of Metals and Polymers . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Fundamental Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Sorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.1 Modes of Sorption . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.2 Sorption in Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.3 Sorption in Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.4 General Sorption Equation . . . . . . . . . . . . . . . . . . . . . . . 14
2.4 Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.4.1 Phenomenological Description . . . . . . . . . . . . . . . . . . . . . 14
2.4.2 Atomistic Description . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.3 Solution of Fick’s Laws . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4.4 Grain Boundary Diffusion . . . . . . . . . . . . . . . . . . . . . . . 19
2.5 Permeation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5.1 Phenomenological Description . . . . . . . . . . . . . . . . . . . . . 22
2.5.2 Experimental Determination of P and D . . . . . . . . . . . . . . . 23
2.5.3 Serial and Parallel Permeation . . . . . . . . . . . . . . . . . . . . . 26
2.5.4 Permeation through Substrates with Defective Liners . . . . . . . . 28
2.5.5 Comparison of Hydrogen and Helium Permeation . . . . . . . . . . 30
2.6 Simulation of Permeation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3 Preselection of Feasible Liner Materials and Production Processes 39
3.1 Literature Review of LH Tank Liners . . . . . . . . . . . . . . . . . . . . 392
3.2 Literature Review of Hydrogen Permeabilities . . . . . . . . . . . . . . . . 41
3.3 Outgassing and Literature Review of Outgassing Rates . . . . . . . . . . . 42
3.4 Vacuum Stability and Material Preselection . . . . . . . . . . . . . . . . . 44
3.5 Literature Review and Preselection of Liner Production Processes . . . . . 46
i4 Materials 51
4.1 Substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.2 Liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.3 Specimens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5 Measurement of Permeation 61
5.1 Room Temperature Permeation Measurement Apparatus . . . . . . . . . . 61
5.1.1 Test Set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.1.2 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.1.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.2 Cryogenic Permeation Measurement Apparatus . . . . . . . . . . . . . . . 67
5.3 Evaluation and Error Estimation . . . . . . . . . . . . . . . . . . . . . . . 71
6 Results and Discussion 73
6.1 Initial Permeation Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.1.1 Reliability of the Measurement Apparatuses . . . . . . . . . . . . . 73
6.1.2 Comparison of Hydrogen and Helium Permeation . . . . . . . . . . 76
6.1.3 Influence of the Feed Pressure . . . . . . . . . . . . . . . . . . . . . 80
6.1.4 Influence of Thermal Cycling . . . . . . . . . . . . . . . . . . . . . 81
6.2 Results of the Permeation Measurements . . . . . . . . . . . . . . . . . . . 82
6.2.1 CFRP Substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.2.2 Metal Sheets and Foils . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.2.3 Metal-plated CFRP . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.2.4 Miscellaneous Coatings on CFRP . . . . . . . . . . . . . . . . . . . 89
6.3 Simulation of Transient Permeation . . . . . . . . . . . . . . . . . . . . . . 90
6.3.1 Simulation of Grain Boundary Diffusion . . . . . . . . . . . . . . . 90
6.3.2 Simulation of Two-layer Permeation . . . . . . . . . . . . . . . . . . 91
6.3.3 Simulation of Permeation through Substrates with Defective Liner . 95
6.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.4.1 Permeation through CFRP. . . . . . . . . . . . . . . . . . . . . . . 97
6.4.2 Permeation through Metal-plated CFRP . . . . . . . . . . . . . . . 98
6.4.3 Evaluation of the Barrier Function of the Liners . . . . . . . . . . . 103
7 Conclusions 105
A Literature Survey of H Permeabilities 1112
B Literature Survey of Outgassing Rates 123
C List of Materials 129
D Measured Data 133
Bibliography 137
iiNotation
List of frequently used symbols
a lattice constant P pre-exponential factor of P0
b width Q gas flow
d diameter of the sealing ring Q outgassing rateG
j normalized flux Q leak rateL
l thickness Q permeation gas flowP
m mass Q throughputT
n pressure exponent (sorption) R universal gas constant (mostly
p pressure (general) in the form of RT)
p, p pressure at feed/permeate side R defect separation distancef p
p vapor saturation pressure S solubility, Henry’s constants
q area specific outgassing rate S pre-exponential factor of SG 0
r defect radius S solubility, Sievert’s constantS
s pumping speed T temperature
s effective pumping speed T T of the measuring chambereff mc
t time T glass transition temperatureg
x coordinate V volume
A area ι barrier constant
C concentration μ chemical potential
0C, C C at the feed/permeate side μ standard chemical potential atf p
D diffusivity standard conditions
D pre-exponential factor of D ν fractional free volume0 f
E activation energy (general) τ dimensionless timea
E , E , E activation energy of D, P, SD P S
J flux Subscripts
J steady-state flux G grainss
M molar mass B grain boundary
N number of particle in mol s substrate
P permeability l liner
iiiList of Abbreviations and Acronyms
bcc body-centered cubic SEM scanning electron microscopy
cAu chemical gold UHV ultra high vacuum
cCu chemical copper
cNiP chemical nickel phosphor ECTFE ethylen/chlortrifluorethylen
fcc face-centered cubic HDPE high density polyethylene
hcp hexagonal close-packed Inconel austenitic nickel-based alloy
Kovar nickel-cobalt ferrous alloy
CFRP carbon fiber reinforced plastic LDPE low density polyethylene
CPMA cryogenic permeation Monel nickel copper iron alloy
measurement apparatus Mylar see PETP
DLC diamond-like carbon PA polyamide
EDX energy dispersive x-ray PBO polyphenylene oxide
FDM finite difference method PC polycarbonate
LH liquid hydrogen PE polyethylene2
LHe liquid helium PETP Polyethylenterephthalat
LN liquid nitrogen PI polyimide2
M01, ... material system number PP polypropylene
PVD physical vapor deposition PTFE polytetrafluoroethylene
QMS quadrupole mass spectrometer PU polyurethane
RT room temperature PVC polyvinyl chloride
RTPMA room temperature permeation SS stainless steel
measurement apparatus Teflon see PTFE
S01, ... specimen number VdC vinylidenchloride
Abbreviation List of Company Names
C01 BMW Group
C02 Oerlikon Space AG
C03 Institut fu¨r Verbundwerkstoffe GmbH
C04 AIMT Holding GmbH
C05 Lu¨berg Elektronik GmbH & Co. Rothfischer KG
C06 Aluminal Oberfla¨chentechnik GmbH & Co. KG
C07 Leistner GmbH
C08 OMT – Oberfla¨chen- und Materialtechnologie GmbH
C09 Universitat Augsburg, Institut fur Physik¨ ¨
C10 MT Aerospace AG
C11 Magna Steyr Space Technology
C12 Linde AG
C13 Alfa Aesar GmbH & Co. KG
C14 Roth GmbH
ivChapter 1
Introduction
Conventional fossil energy sources like coal, oil and natural gasare only time-limited avail-
able [1–11]. Additionally, the emission of carbon dioxide owing to the combustion of fossil
energy sources is made responsible for the increasing greenhouse effect and therefore for
the global warming [12–15]. Hydrogen (H ) is an alternative energy carrier that does not2
contain carbon. Its usage as a fuel in automobiles is the subject of recent research and
development. Thereby, the storage of H on board is an essential issue. One technical2
solution is the storage of liquefied hydrogen (20K, 1 – 6bar) in vacuum insulated tank
vessels. Liquid hydrogen (LH ) tanks made of carbon fiber reinforced plastics (CFRP) are2
of special interest because they enable lightweight structures. However, the permeation of
hydrogenthroughCFRP,apotentialsourceofdeterioratingthevacuum, isstillachallenge
to be solved.
Automotive LH Tank and its Vacuum Insulation2
The minimization of arbitrary heat fluxes into the liquid hydrogen is one of the key issues
when developing a LH tank. Heat transfer leads to an evaporation and hence to a loss2
of hydrogen. Vacuum insulations, as employed in thermo flasks, provide the most efficient
protection.
Figure 1.1 illustrates the LH tank of the BMW Hydrogen 7. Conce