cfd based modelling approaches for hydrogen safety … · cfd based modelling approaches for...

CFD based modelling approaches

for hydrogen safety issues

Jennifer Wen

Warwick FIRE, School of Engineering

FIRE http://www.warwick.ac.uk/warwickfire

Outline

• Spontaneous ignition

• Hydrogen jet fires

• Hydrogen deflagration, DDT and

detonation

Centre for Fire and Explosion Studies

Safety relevant properties of

hydrogen/ methane/propane/gasoline vapour

density buoyancy

Heat of combustion Laminar burning

velocity

Flammability range Minimum Ignition energy

Diffusion coefficient

Detonation sensitivity



Spontaneous ignition

FIRE

Spontaneous ignition: two types

of release scenarios

Direct release into air Release through a section

of tube


Own modified version of KIVA-3V

2-D Unsteady Compressible Navier-Stokes equations solved with an Implicit Large eddy simulation (ILES) method

Arbitrary Lagrangian Eulerian (ALE) numerical scheme: convective term solved separately from diffusion terms;

In Lagrangian stage, 2nd-order Crank-Nicolson scheme + 2nd-order central differencing for diffusion and pressure related terms;

In Eulerian phase, 3rd-order Runge-Kutta method + 5th-order upwind weighted essentially non-oscillatory (WENO) scheme for convection terms;

Detailed chemical-kinetic scheme - 8 reactive species and 21 elementary steps –third body and “fall off” behavior considered (Williams 2006);

Multi-component diffusion approach for mixing - thermal diffusion;

Iris model mimics the rupture process

Spontaneous ignition

Validation - Comparison of 1-D release case with

theoretical results based on 1-D shock wave theory

10-micron gird size and a 5th-order WENO scheme


Release through a tube D=3mm, L=6cm)

Release tubes with varied cross-sections – all

with 50 bar pressure

(a) Local contraction

(b) Local enlargement

(c) Abrupt contraction

(d) Abrupt enlargement


Hydrogen Jet Fires


Hydrogen Jet Fires - Two Modelling Approaches

• Pseudo-source approach

(Ewan and Modie 1985)

– Leak modelled from downstream as a sonic jet

with the same mass flow

rate

• Two-domain approach

Numerically solving the

under-expanded shock structure

• Results used as inflow for

the subsequent large eddy simulation of the jet

0 .5( 0 .5 3 6 )

o

e q j D

a

PD D C

P

/ 12( )

1e o

P P

/ 12( )

1e o

1 / 2 1 / 24 .9 9( )

gs

o D

a

DY C

z

Comparison of the predicted mean

temperatures by the two- approaches

Hydrogen jet flame test

Sandia Laboratory

0

1

2

3

4

5

6

1 0 .5 0

the two-domain approaches

the Pseudo source approach


Hydrogen jet fires

• FireFOAM code with own modified EDC - Zhibin Chen, Jennifer Wen, Baopeng Xu, Siaka Dembele, Large eddy simulation of a medium-scale methanol pool fire using the

extended eddy dissipation concept, International Journal of Heat and Mass Transfer, Volume 70, March 2014, Pages 389-408.

- Zhibin Chen, Jennifer Wen, Baopeng Xu, Siaka Dembele, Extension of the eddy dissipation concept and smoke point soot model to the

LES frame for fire simulations, Fire Safety Journal, Volume 64, February 2014, Pages 12-26.

• Finite volume discrete ordinates model (fvDOM)

• Weighted sum of grey gas model for radiation


Nozzle Diameter: 5.08mm

Pressure: 104.8atm

Tank temperature:231.4K

Schefer, R.W., Houf, W.G., Williams, T.C., Bourne B. and Colton, J., Characterization of High-pressure, Underexpanded Hydrogen-jet Flames,

International Journal of Hydrogen Energy, 32, 2007, pp. 2081-2093.

The under-expanded hydrogen jet fire of Schefer et al.

FIRE http://www.warwick.ac.uk/warwickfire 15

The under-expanded hydrogen jet fire of Ekoto et al. Ekoto, I.W., Houf, W.G., Ruggles A.J., Creitz, L.W. and Li, J.X., Large-scale Hydrogen Jet Flame Radiant Fraction

Measurements and Modelling, Proceedings of the 2012 9 th the International Pipeline Conference, Calgary, Alberta,

Canada, 2012, Paper IPC2012-90535, 2012.


Hydrogen explosions

• Deflagration: the combustion or reaction

wave propagates at a velocity less than the

speed of sound.

• Deflagration to detonation transition (DDT)

refers to a phenomenon in ignitable mixtures of

a flammable gas and air (or oxygen) when a sudden transition takes place from a

deflagration type of combustion to a detonation

type of combustion.

• Detonation: the combustion or reaction wave

propagates at a velocity faster than the speed

of sound.


CFD modelling of hydrogen deflagration T. Tanaka, T. Azuma, J.A. Evans, P.M. Cronin, D.M. Johnson, R.P. Cleaver, Experimental study on hydrogen explosions in a full-scale

hydrogen filling station model, Int J of Hydrogen Energy, 32(13), 2007.

Osaka Gas’ Hydrogen

station

Chamber structure for

explosion experiments

3.0

2.0

1.0

0


CFD modelling of hydrogen deflagration

induced by ignited jet release

Shirvill, L.C., Royle, M. and Roberts, T.A., Hydrogen release ignited in a simulated vehicle refuelling

environment, Proc. 2nd Int Conf on Hydrogen Safety, Sep. 11-13, 2007, San Sebastian, Spain.


• Own modified version of OpenFOAM

• Williams’ [13] 21-step hydrogen autoignition mechanism

• Single step reaction was taken from Gamezo et al.

• A single step chemistry derived by ourselves

Hydrogen deflagration, DDT and detonation

FIRE

Hydrogen deflagration, DDT and detonation –

Validation of the single step chemistry

1D steady ZND wave Free-propagating laminar flame


DDT A. Teodorczyk, P. Drobniak, A. Dabkowski, “Fast turbulent deflagration and DDT of hydrogen–air mixtures in small obstructed

channel”, International Journal of Hydrogen Energy, Volume 34, Issue 14, July 2009, Pages 5887-5893

Distance to left end 475mm 595mm

Peak

Pressure

Meas. 3.6MPa 6MPa

Pred. 3.75MPa 5.81MPa

Discrepancy 4.2% 3.2%

Ignition

FIRE

Measured Predicted

DDT - Validation

• 80 mm×2000 mm tube, L=160 mm, BR = 0.5

• Smallest grid size : 20 micron, structured (AMR)

• Boundary conditions : no-slip reflecting boundaries.

• Fuel: stoichiometric Hydrogen-air mixture

• Ignition: a region of high temperature (2000 K)

FIRE

Detonation propagation in a bifurcated tube

C. J. WANG, S. L. XU AND C. M.

GUO, “Study on gaseous detonation

propagation in a bifurcated tube”,

Journal of Fluid Mechanics (2008),

599: 81-110


Summary of modelling approaches presented

• A dedicated code for spontaneous ignition modified from

Kiva-3V

• A modified FireFOAM code for hydrogen jet fires

• A modified OpenFOAM with newly developed single step

hydrogen reaction cover the full range from laminar to

flames, turbulent deflagration, DDT and detonation


• Sponsors European Commission

The Engineering and Physical Science

Research Council, UK (EPSRC)

FM Global

The National Natural Science Foundation of

China

• Collaborators The Heath and Safety Laboratory

BP

University of Ulster

Warsaw University of Technology

University of Science and technology, China

• Researchers Baopeng Xu

Sergio Ferraris

Changjian Wang

Zhibin Chen

Vendra Madhav Rao

EL Hima

Jianping Zhang

Ali Heidari

• Former colleagues Vincent Tam

Siaka Dembele

Siva Muppala

Acknowledgement

cfd based modelling approaches for hydrogen safety … · cfd based modelling approaches for...

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