hydrogen storage for automotive tanks using hydrostatic

Hydrogen Storage for Automotive Hydrogen Storage for Automotive Tanks Using Hydrostatic Tanks Using Hydrostatic Pressure Pressure RetainmentRetainment (HPR) (HPR) MicrostructureMicrostructureBhavin Mehta, Greg Banyay, Housila TiwariOhio University

David Hill, Saurin MehtaInergy Automotive

Mark Biernacki, Steve BarnhartDaimlerChrysler

Ohio University - Mechanical Engineering 2

Hydrogen StorageHydrogen Storage

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1. Pressurized Gas Cylinderstraditional, but potential dangerous and requires expensive materials

2. Liquefied Cryogenic Storagebetter volumetric energy density, but difficult to insulate and high cost of liquefaction

3. Hydrides (Metal / Chemical)potentially safe, inexpensive, but very heavy and/or unstable

4. Innovative Techniques (ie: nanotechnology, HPR…)promising techniques that require more research/validation

Current Methods

Nonetheless, the problem is still not solved…


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Ideal FoamIdeal Foam

This is a novel concept for gas storage. Gas is stored in small bubbles of a foam matrix, thereby forming a series of small spherical pressure vessels. The resulting stress in the material between the bubbles is in a hydrostatic state of tri-axial tension.

Structural Efficiency ={(100 + 100 + 100)/3=100%}

HPR Description


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Ideal FoamIdeal FoamHPR Description

Advantages:1) Conformability

Automotive Frames are designed before gas tanks, so the tank must be designed around the frame – not vice-versa

2) SafetyIn the case of an accident, only the gas contained in the adjacent cells tothe fracture location would dispel at once

3) Weight SavingsIn theory, because the matrix material is in a state of hydrostatic tension,the material is being utilized 100% in all 3 cartesian directions – thus requiring less material


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Ideal FoamIdeal Foam

SC Unit Cube52% packing efficiency

BCC Unit Cube68% packing efficiency

FCC Unit Cube74% packing efficiency

Expanded BCC Lattice

optimized cell size is @ 95% of the touching radius

Materials Examined:• Stainless Steel• Aluminum• HDPE

Idealized Model Summary


ObjectiveObjective

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While ideal HPR pressure vessels have been proven a feasible concept, the material behavior of actual cellular materials must be examined.

This research has the objective of both developing an efficient methodology for examination of actual cellular polymers and applying these methods to actual foam.


Work Scope and ApproachWork Scope and Approach

1. Data Acquisition: foam samples, SEM, micro-CT

2. Image Construction: image filtration/segmentation in Amira

3. Mesh Construction: triangular surface generated, cleaned, and constructed into tetrahedral solid mesh

4. FE Model Validation: simulated compression test and comparison of foamyield strength to bulk material yield strength

5. FEA HPR Analysis and Results:using Altair Hypermesh/Optistruct

6. Results Interpretation: MS Excel spreadsheet/Matlab programs developed tofind meaningful tank parameters


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TheoryTheory

1−=foam

p

p

void

VV

ρρ

FCC βcos4.. ⋅⋅= trLE

θβ coscos4.. ⋅⋅⋅= trLE

trLE ⋅= 2.. 223 23_ −⋅+⋅−= nnnN SCbubbles

2232 23_ −⋅+⋅−⋅= nnnN BCCbubbles

1364 23_ −⋅+⋅−⋅= nnnN FCCbubbles

SC

BCC

Governing Equations of HPR Spreadsheet

for ideal models…

for actual models… for all models…

( ) [ ] 22

1VABV

VTRp −+⎥⎦

⎤⎢⎣⎡ −⋅⋅

=ε

to determine various tank parameters given criteria such as pressure, material,temperature, and cell arrangement, certain equations were developed…


TheoryTheory

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xfixed H2mass


fixed tank volume


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Actual FoamActual Foam

DIAB Divinycell H130: Cross-Linked PVC Foam

Mearthane Durethane DF-630A: Elastomeric Polyurethane Foam

SEM Images


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DIAB Divinycell H130: Cross-Linked PVC Foam

Mearthane Durethane DF-630A: Elastomeric Polyurethane Foam

image slice fromBrookhaven National

Laboratory(reconstructed .bmp)

reconstructed imagedataset from OU

micro-CT scanner(GE Microview Software)

mesh renderingin Amira

mesh renderingin Amira

X-ray Computed Micro-Tomography


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Useable FE Model Generation1) Image Filtration: median – dilation – erosion

2) Selection of Region of Interest

• smaller regions were selecteddue to limited computing capacity

• the single large box represents the entirefoam dataset while the multiple smallerboxes represent the chosen models


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Useable FE Model Generation3) Surface Smoothing

although a smoothed surface was more aesthetically pleasing,it contained skew elements from which valid FE models could notbe constructed


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Useable FE Model Generation

for most models, the mesh did not needto be coarsened

in other words, the maximum possibleMesh density was desirable

however, to generate “large” modelsencompassing more foam volume, themesh needed to be coarsened

this was done using a re-samplingalgorithm that restricted elements fromintersecting


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PVC

E (psi) 175000

σ, yield (psi) 6500 +/ 500

ρ (lbs/in^3) 0.047

ν 0.32

Material Properties

H130

E, tensile (psi) 20300

E, compressive (psi) 25375

Tensile Strength (psi) 609

Compressive Strength (psi)

363

Density (lbs/in^3) 0.00469

DF-630A

E (psi) 140Ultimate Tensile Strength (psi) 4700Compressive Yield Strength @

30% Deflection (psi)125

Density (lbs/in^3) 0.0173

Polyurethane

E (psi) 200

σ, uts (psi) 5500 +/- 500

ρ (lbs/in^3) 0.043

ν 0.32

BULK MATERIAL (FEA)FOAM PROPERTIES

DF-

630A

H13

0

OTHER PROPERTIES

Cell Diameter = 350 μm

Vvoid/Vstructure = 9

Cell Diameter = ~100 μm

Vvoid/Vstructure = 1.5


Compression TestingCompression Testing

Verification of DIAB’spublished values

DIAB Divinycell H45, H60, H130


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Finite Element AnalysisFinite Element Analysis

Foam Model Validation

y = 17.237x + 0.0768y = 16.325x + 0.2062

R2 = 1

0

1000

2000

3000

4000

5000

6000

7000

0 50 100 150 200 250 300 350 400

Foam Stress: Compressive Load (psi)

PVC

Str

ess:

max

imum

Von

M

ises

(psi

)

Ideal Behavior H130_8 Linear (Ideal Behavior) Linear (H130_8)

Model Validation


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Preprocessing

Fixed Center Node• localized stress concentration• large displacements

Face Single Node• localized stress concentrations• deformation restricted



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maximum stresses

probable governing stresses

Preprocessing6-Face Boundary Condition: • Deformation Imperfect

• Max stress loc. unpredictable


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Preprocessing

Single-Face Boundary Condition• for purposes of examining foam

about the periphery of the tank which is attached to a rigid outershell



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Model ID Ntetra4 Papplied σmax_V.M. PMAX σavg_V.M. Pprobable

H130_1_small 925915 50 3710.00 87.60 9.00E+02 3.61E+02

H130_2_small 335526 50 1210.00 268.60 3.00E+02 1.08E+03

H130_3_small 1338114 50 1440.00 225.69 4.10E+02 7.93E+02

H130_4_small 780144 20 342.00 380.12 9.71E+01 1.34E+03

H130_5_small 623316 20 1890.00 68.78 5.40E+02 2.41E+02

H130_6_small 834414 20 234.00 555.56 6.60E+01 1.97E+03

H130_5 341171 20 492.00 264.23 1.40E+02 9.29E+02

H130_8 739028 20 827.00 157.19 2.00E+02 6.50E+02

mean = 250.97 920.62

standard deviation = 160.02315 556.376882

all units in PSI

H130 Results: 6-face BC


Tank ParametersTank Parameters

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Pressure vs. Hydrogen Mass for 60 gallon tank

DF-630A, Pressure vs. H2 Mass

y = 137.35x2 + 961.49x - 17.304R2 = 0.9999

0.00

1000.00

2000.00

3000.00

4000.00

5000.00

6000.00

0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000

M ass of Hydrogen (kg)

Pres

sure

(psi

)

497003722

260,130 −⋅+⋅= HHgalH mmP 17961137

22

260,630 −⋅+⋅=− HHgalADF mmP


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H130, V vs. P

y = 171.84x-0.7617

R2 = 0.9878

0

2

4

6

8

10

12

14

16

18

0.00 500.00 1000.00 1500.00 2000.00 2500.00

Pressure (ps i)

Tank

Vol

ume

@ 5

kg H

2 (m

^3)

DF-630A, V vs. P

y = 333.2x-0.8123

R2 = 0.9947

0

5

10

15

20

25

0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00

Pressure (ps i)

Tank

Vol

ume

@ 5

kg H

2 (m

^3)

7617.05,130 2

8.171 −⋅= HkgH PV 8123.05,630 2

2.333 −− ⋅= HkgADF PV

Tank Volume vs. Pressure for 5 kg Hydrogen



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xH130, Eff vs. P

y = -3E-09x2 + 5E-05x + 0.0023R2 = 1

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

7.00%

8.00%

9.00%

0.00 500.00 1000.00 1500.00 2000.00 2500.00

Pressure (ps i)

Mas

s Ef

ficie

ncy

(kg/

kg)

DF-630A, Eff vs. P

y = -4E-10x2 + 8E-06x + 0.0005R2 = 1

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

3.00%

3.50%

0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00

Pressure (psi)

Mas

s Ef

ficie

ncy

(kg/

kg)

0023.010510322

529130 +⋅×+⋅×−= −−

HHH PPη 0005.010810422

6210630 +⋅×+⋅×−= −−

− HHADF PPη

Mass Efficiency vs. Pressure


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Summary of ResultsSummary of Results

H130 DF-630A 2007 FreedomCAR Goals

Withstand-able Pressure 900 psi 3000 psi n/a

H2 Mass for 60 gal tank 1.2 kg 2.5 kg 8.18 kg

Tank Volume for 5kg H2 343 gallons 132 gallons 36.68 gallons

Mass Efficiency 3.5% 2.3% 4.5%

Volumetric Capacity 0.0056 kg H2 / L 0.0104 kg H2 / L 0.036 kg H2 / L

Optimistically Scaled


Ideal HPR matrix Results for BCC StructureIdeal HPR matrix Results for BCC Structure

• Material: DIAB H130

• Table 1: Effect of varying bubble sizes on pressure and tank size

Unit Cube Edge (a) = 100 0.60 0.70 0.95 Bubble Radius 26.0 30.3 41.1

Von Misses @P=500 psi 485 869 2350Max Pressure( psi) 3763 2100 778

Mass of H2 (kg) 4.60 4.47 4.44No. Of Bubbles 3925 3925 3925

Tank Size 2.20 2.20 2.20Void Fraction % 13.15 20.82 51.95mH2/mStructure 3.97% 4.24% 6.93%

rTrTrT


5 Gal Tank Provided by Inergy5 Gal Tank Provided by Inergy


Simulation results for 5 Gal Tank with DIAB H130Simulation results for 5 Gal Tank with DIAB H130

This tank was simulated to withstand highest pressure before yielding.

Results obtained are as follows:

Maximum Pressure without yielding = 1148 psi for YS= 3650 psiMass of H2 in tank = 0.04904278 kgMassH2 / mass STRUCTURE = 3.01%

For Storing 5 kg of Hydrogen the tank size needs to be 1.86 m3 which is almost 3.95 (~4) times the size of actual tank.

So the actual tank using DIAB H130 would be of the following dimensions:

2710 mm x 1500 mm x 670 mm


Summary SheetSummary Sheet

Material Steel Aluminum PolycarbonatePolyurethane(Composite)

DIAB H130(Foam)

Radius 41.1 41.1 41.1 41.1 41.1

Max Von Misses Stress 2100 2130 2100 2100 2350

Max Pressure( psi) 9524 13451 2310 10452 778

Tank size (m^3) 0.34 0.28 0.93 0.32 2.2

Tank size (gallons) 77 63 211 73 500

Tank dimensions (mm) 1200 x 840 x 370 1150 x 800 x 350 1650 x 1140 x 510 1200 x 840 x 370 2710 x 1500 x 670

Weight (Kg) 1415 405 586 271 70

mH2/mStructure 0.35% 1.23% 0.85% 1.85% 7.07%


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ConclusionsConclusions

• The ideal models illustrate that HPR is a feasible solution to the hydrogen storage problem for the following 3 reasons:1. Conformability2. Weight Savings3. Minimized Safety Risk

• Neither H130 nor DF-630A meet the goals set by the DOE FreedomCAR project

• An efficient method for examination of polymeric foam for HPR application has been developed

• Composite foam structures can be pursued, which could greatly increase tank performance

• Back to metals (Metal foams, hollow spheres etc)


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Recommendations for Future WorkRecommendations for Future Work

If it is verified that a non-composite foam is not suitable…Pursue Composite Foam

attain samples and examine using the methods developedin this thesis

Develop relationships between foam yield strength/modulus andHPR behavior

Expand the scope of the work past static structural analysis, toconsider thermal loads, potential chemical reactions, permeability andsorption rates, tank refuel-ability, quantifiable co$t, etc.

If/When a practical foam is found, perform experimental tests of an actualhydrogen-pressurized tank


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Questions?Questions?

http://www.ohio.edu/

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hydrogen storage for automotive tanks using hydrostatic

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