Non-adiabatic blowdown modelV. Molkov, M. Dadashzadeh,D. Makarov, S. Kashkarov

Digital Stakeholders WorkshopHyTunnel-CS project

4-5 May 2020

ModelTank parameters

Parameter Value Reference Type IV tank

Internal volume, L 19 (Acosta et al., 2014)Internal diameter, mm 180 (Acosta et al., 2014)External diameter, mm 228 (Acosta et al., 2014)External length, mm 0.904 (Acosta et al., 2014)TPRD diameter, mm 1 KIT test

HDPE* linerThickness, mm 7 (Welch et al., 2017)Thermal conductivity, W/m/K 0.385 (Monde and Kosaka, 2013)Specific heat capacity, J/kg/K 1584 (Monde and Kosaka, 2013)Density, kg/m3 945 (Monde and Kosaka, 2013)

CFRP* structural layerThickness, mm 17 (Welch et al., 2017)Thermal conductivity, mm 0.5 (Hidalgo et al., 2016)Specific heat capacity, J/kg/K 1020 (Hidalgo et al., 2016)Density, kg/m3 1360 (Hidalgo et al., 2016)

* HDPE: high density polyethylene; CFRP: carbon fibre reinforced polymer.

ModelInside the tank§ Energy conservation

!"!#= !$

!#− ℎ%&#

!'!#

, ℎ%&# = 𝑐(,*𝑇+ + 𝑏𝑃+

§ Real gas internal energy

𝑈 = ,!(./'!0)2/+

§ Rate of heat transfer

!$!#= 𝑘34#𝐴34# 𝑇5 34# − 𝑇+ , 𝑘34# =

6"×8&#$%9$%&

§ Nusselt number correlation

𝑁𝑢934 = 0.104× *: ;!/;' $%& <(," =! *9$%&+

>"6"

?.ABC

1

Ttank

Tw (liner)

Tw (CFRP)

Tamb Tw (ext)

Tw (int)

External surface of the wall: convection (ambience-wall external surface)

Wall: conduction (tank wall, i.e. CFRP, liner)

Internal surface of the wall: convection (wall internal surface-inside gas)

kext

kint

2 3

ModelActual nozzle§ Transcendental equation to calculate density at TPRD exit

!!"#$!!

%= !"

"#$!"

%" 1 + %#"

& "#$!" "

'# #$!

§ Energy conservation equation(!("= 1 + %#"

& "#$!" "

§ Abel-Noble EOS

𝑃& =!")%(""#$!"

§ Local sound velocity*

𝑢& =𝛾𝑅*𝑇&

+.-

1 − 𝑏𝜌&

* Considering the chocked flow at the orifice, the gas velocity is assumed to be equal tothe local sound velocity (Molkov, 2012).

1

Ttank

Tw (liner)

Tw (CFRP)

Tamb Tw (ext)

Tw (int)

External surface of the wall: convection (ambience-wall external surface)

Wall: conduction (tank wall, i.e. CFRP, liner)

Internal surface of the wall: convection (wall internal surface-inside gas)

kext

kint

2 3

ModelNotional nozzle§ Energy conservation equation

𝑇. =&("%/"

+ %#"%/"

" 0"!" "#$!" )%

§ Abel-Noble EOS

𝜌. =0&'(

0&'($/)%()

§ Local sound velocity*

𝑢. =%)%()

*.,

"#$!)

§ Continuity equation

𝐷. = 𝐷& 𝐶1!"2"!)2)

Mass flow rate

�̇� =𝜌!𝑢!𝜋 𝐷! "

4

* At the notional nozzle, the gas velocity is assumed to be equal to the local soundvelocity (Molkov, 2012).

1

Ttank

Tw (liner)

Tw (CFRP)

Tamb Tw (ext)

Tw (int)

External surface of the wall: convection (ambience-wall external surface)

Wall: conduction (tank wall, i.e. CFRP, liner)

Internal surface of the wall: convection (wall internal surface-inside gas)

kext

kint

2 3

Pressure simulation vs experiment Temperature simulation vs experiment

Ref.: Dadashzadeh et al., 2019, ICHS, Sep. 24-26, Adelaide, South Australia.

Blowdown validationTest with helium

0

100

200

300

400

500

600

700

800

0 25 50 75 100 125 150 175 200 225 250 275 300

Pres

sure

(ba

r)

Time (s)

KIT experimentSimulation-adiabatic model (Molkov et al., 2009)Simulation-Ulster non adiabatic model

20

70

120

170

220

270

0 25 50 75 100 125 150 175 200 225 250 275 300

Tem

pera

ture

(K

)Time (s)

KIT experimentSimulation-adiabatic model (Molkov et al., 2009)Simulation-Updated Ulster non-adiabatic model

Concluding remarks

§ The model is validated against helium blowdown test: temperature and pressure dynamics in a tank.

§ This sub-model is a part of a bigger model developed for hydrogen safety engineering of a system TPRD-storage tank.

§ The bigger model allows for determining a safe performance of a tank in a fire with specified fire intensity (heat flux to the tank), tank parameters and speed of thermal degradation in a fire, time to TPRD activation, TPRD orifice etc.

This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (JU) under grant agreement No 826193. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and United Kingdom, Germany, Greece, Denmark, Spain,Italy, Netherlands, Belgium, France, Norway, Switzerland.

Acknowledgements