Type IV COPV Cold Gas Operation Challenges

DAVID W. GOTTHOLD

November 30, 2015 1

Pacific Northwest National Laboratory

Cold Gas Motivation and Challenges

November 30, 2015 2

200 K H2

Lower pressure

Higher density H2

CGO ~25% CF savings

Cost Savings from reduced CF use

Cold gas operation allows for reduced pressures for the same volume for significant CF and cost reductions.

Materials properties change significantly at cold gas temperatures and must be studied. Example: HDPE DBT ~ 200 K

Higher operating temperature improves dormancy for equivalent R-factor

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pera

ture

, K

Pres

sure

, bar

Time, Days

Cold Gas Tank Pressure, barCryo-Compressed Tank Pressure, barCold Gas Temperature, KCryo-Compressed Temperature, K

Cryo, Pmax=340 bar

Cold Gas, Pmax=625 bar

Key Cold-Gas Challenges

Operation conditions near or below transition temperatures of many common polymers

HDPE DBT ~200K (set lower operating temperature)

Thermal cycling across a wide temperature range

-73C to +60C Temperature crosses condensation point

Thermal expansion mismatch Polymer-metal interface at boss Liner/composite shrinkage

November 30, 2015 4

Low Temperature Materials Data

November 30, 2015 5

Use

Material

Reported Useful Temp Range, ⁰C

Tg , ⁰C

Tm , ⁰C

Linear CTE, 10-5/C

Valve Seals Viton -23 / +204 -20 260 8.3 – 10.5

Nitrile Rubber (Buna-N) -34 / +250 --------- 11.2

Teflon (PTFE) -100 / +260 115 335 10

EPR (ethylene-propylene-rubber) -62 / +160 -60 ---------

Fluorosilicone -59 / +232 -50 --------- 81 (low Temp)

Silicone -62 / +216 -50 --------- 18 – 25.5

Neoprene -40 / +121 -43 --------- 61 - 72

Valve Pistons PEEK / +250 143 343-374

Valve Seats Nylatron / +105 260 6.3 – 10.6

Vespel -100 / +500 none observable

none observable

2.7 – 5.4

PCTFE 45 215 7

Tanks: Resin Epoxy

Vinylester

Liner HDPE -110 130 12

PPS (polyphenylene Sulphide) / +220 282 5

Nylons 50 255 8-10

Low Temperature Materials Data

November 30, 2015 6

Use

Material

Reported Useful Temp Range, ⁰C

Tg , ⁰C

Tm , ⁰C

Linear CTE, 10-5/C

Valve Seals Viton -23 / +204 -20 260 8.3 – 10.5

Nitrile Rubber (Buna-N) -34 / +250 --------- 11.2

Teflon (PTFE) -100 / +260 115 335 10

EPR (ethylene-propylene-rubber) -62 / +160 -60 ---------

Fluorosilicone -59 / +232 -50 --------- 81 (low Temp)

Silicone -62 / +216 -50 --------- 18 – 25.5

Neoprene -40 / +121 -43 --------- 61 - 72

Valve Pistons PEEK / +250 143 343-374

Valve Seats Nylatron / +105 260 6.3 – 10.6

Vespel -100 / +500 none observable

none observable

2.7 – 5.4

PCTFE 45 215 7

Tanks: Resin Epoxy

Vinylester

Liner HDPE -110 130 12

PPS (polyphenylene Sulphide) / +220 282 5

Nylons 50 255 8-10

There is a lot of missing and incomplete data in the temperature ranges of interest

November 30, 2015 7

Cold Gas Capability at PNNL

To investigate materials compatibility at enhanced operating conditions of cold gas operation, PNNL has expanded our cold temperature capability

New mechanical test frame capable of -129 C up to 315 C for all materials IR camera for thermal imaging and evaluation of advanced physical insulation for cold gas operation

November 30, 2015 7

Enhanced environmental chamber on test frame Enhanced environmental

chamber (inside)

Thermal image of cold chamber

Preliminary polymer test results

PNNL started preliminary testing of baseline polymers from -129C to room temperature Preliminary data from HDPE, Teflon, and nylon in progress HDPE – clear ductile/brittle transition observed

November 30, 2015 8

Preliminary polymer test results

HDPE modulus increases as temperature decrease Ductile/brittle transition occurs below -100 C Teflon and Nylon tests in progress, other materials to follow

November 30, 2015 9

RT -10 C -40 C -70 C -100 C -129 C

HDPE Tensile Testing

Example data for Cold Polymers

In general, as temperature goes down:

Modulus increases Strength increases (then decreases) Strain to failure decreases Transitions occur

Ductile Brittle Transitions occur Related to glass transition temp Example HDPE ~ 200K

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Exte

nsio

n at

Bre

ak (m

m)

Temperature (C)

Maximum Extension vs Temperature

HDPE DBT

0102030405060708090

-120 -100 -80 -60 -40 -20 0 20 40

Exte

nsio

n at

Bre

ak (m

m)

Temperature (C)

Maximum Extension vs. Temperature

teflon

Additional test capabilities

In addition to cold gas mechanical testing, PNNL can test polymers with DMA at cold temperatures to investigate transition temperatures to determine potential material problems\ -150 C to room temperature (and up to 650 C)

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Loss

Mod

ulus

(MPa

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Stor

age

Mod

ulus

(MPa

)

Temperature (°C)

Halar Storage Modulus PE Storage Modulus Kynar 6000 Storage Modulus Kynar 9000-4 Storage Modulus Kynar 9000-8 Storage Modulus

Halar Loss Modulus PE Loss Modulus Kynar 6000 Loss Modulus Kynar 9000-4 Loss Modulus Kynar 9000-8 Loss Modulus

Previous DMA results for multiple polymers (loss and storage modulus)

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Loss

Mo

du

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a)

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rag

e M

od

ulu

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Pa

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Temperature (°C)

Heating Ramp

Storage Modulus Loss Modulus

Previous DMA data for UHMWPE

Insulation for cold operation

Advanced physical insulation such as vacuum insulation panels (VIP) will likely be the only physical insulation capable of achieving required dormancy VIP material typically vacuum packaged fumed silica (FS) in stiff board-like configuration – most aluminized mylar packaging Quilted (non vacuum packaged, VP) material also available – would need to vacuum package after tank wrap

November 30, 2015 12

Quilted FS (not VP) VIP-AM (vendor 1) VIP-AM (vendor 2) VIP (vendor 2)

Thermal testing of insulation

In process of designing test frame for thermal testing of different insulations and joining at enhanced operating conditions – evaluation with thermal imaging

November 30, 2015 13

VIP insulation – high performance Other insulation – poor performance

No cold spot

VIP insl.

Dry ice

cold spot

other insl.

Dry ice

Unknowns

Fatigue and impact behavior both at low temperatures and after thermal cycling Scaling of materials testing from coupons to full tanks Effect of fill process on liner stability Vibration stability of advanced insulation

November 30, 2015 14

Collaborations

Pacific Northwest National Laboratory: David Gotthold (PI), Ken Johnson, Kyle Alvine, Matt Westman

Project management, material and cost models, resin modifications

Hexagon Lincoln: Norm Newhouse, Brian Yeggy, Alex Vaipan

Tank modeling, tank fabrication, tank and materials testing

Ford Motor Company: Mike Veenstra, Dan Houston

Enhanced operating conditions, cost modeling, materials testing

Toray Carbon America: Anand Rau* Carbon fiber surface modification and testing

AOC Resins: Thomas Steinhausler, Mike Dettre Resin system design and materials testing

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