LIMITS OF STEADY PROPAGATION OF HYDROGEN DEFLAGRATIONS AND - - PowerPoint PPT Presentation

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LIMITS OF STEADY PROPAGATION OF HYDROGEN DEFLAGRATIONS AND - - PowerPoint PPT Presentation

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LIMITS OF STEADY PROPAGATION OF HYDROGEN DEFLAGRATIONS AND DETONATIONS Andrzej Teodorczyk Warsaw University of Technology 1 Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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LIMITS OF STEADY PROPAGATION OF HYDROGEN DEFLAGRATIONS AND DETONATIONS

Andrzej Teodorczyk

Warsaw University of Technology

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Flame propagation in tubes

  • Lower limit

⇒ LAMINAR FLAME (m/s)

  • Upper limit

⇒ CJ DETONATION (km/s)

  • Between limits ⇒ spectrum of TURBULENT FLAMES

depending on:

  • Initial conditions: pressure, temperature, composition
  • Geometry: size, obstacles, etc.
  • Smooth tubes

⇒ continuous flame acceleration and abrupt DDT

  • Rough (obstructed) tubes ⇒

several distinct regimes

  • f steady flame propagation
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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Experimental Composition Limits

Source: Kuo, Principles of Combustion, 2005

36.5 4.5 2.8 1.85 C4H10O – air 93 92 3.5 2.8 C2H2 – O2 55 37 3.2 2.4 C3H8 – O2 79 75 25.4 13.5 NH3 – O2 71.8 59 19 6.05 (CO+H2)–air 92 91 17.2 12.5 (CO+H2)–O2 93.9 90 38 15.5 CO – O2 74 59 18.3 4 H2 – air 93.9 90 15 4.6 H2 – O2 Deflagration rich limit [% fuel by vol.] Detonation rich limit [% fuel by vol.] Detonation lean limit [% fuel by vol.] Deflagration lean limit [% fuel by vol.] Mixture

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Progress of DDT event in a smooth tube

a) the initial configuration showing a smooth flame and the laminar flow ahead; b) first wrinkling of flame and instability of the upstream flow; c) breakdown into turbulent flow and a corrugated flame; d) production of pressure waves ahead of the turbulent flame; e) local explosion of a vertical structure within the flame; f) transition to detonation.

(Shepherd&Lee, 1992)

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Premixed flames in smooth closed tube - stoichiometric hydrogen-oxygen

(Kuznetsov M., Dorofeev S., 2005)

Shock wave Boundar y layer

Effect of boundary layer on the flame acceleration and DDT

Shadow photograph of early stage of flame propagation p0=0.75 bar at 210-440 mm from ignition Ignition by electric spark of 20mJ

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Regimes of flame propagation leading to DDT

Source: S.Dorofeev et al., Journal of Loss Prevention in the Process Industries 14 (2001) 583–589

( )

2 b u b a

RT T T E − = β

Zel’dovich number: Expansion ratio:

b u

ρ ρ σ =

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Regimes of flame propagation leading to DDT

Source: S.Dorofeev et al., Journal of Loss Prevention in the Process Industries 14 (2001) 583–589

Explosion limits for H2/air/H2O mixtures at T=500 K and p=1 atm. Range of uncertainty of fast flame boundary is shown by dotted lines

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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CJ Detonation

1932 78.3 3868 39.9 2343 7.4 C8H18

  • ctane

1907 55.6 3728 29.4 2394 33.3 CH4 methane 1987 76.3 3854 39.1 2358 13.3 C4H10 butane 1931 70.4 3830 36.3 2360 16.7 C3H8 propane 1933 65.6 3803 34 2373 22.2 C2H6 ethane 2037 64.1 3938 33.5 2376 25.0 C2H4 ethylene 2239 64.5 4213 33.9 2425 28.6 C2H2 acetylene 1770 33.1 3683 18.9 2842 66.7 H2 hydrogen Fuel – oxygen mixtures 1541 30.3 2832 18.6 1796 1.62 C8H18

  • ctane

1530 31.2 2781 17.2 1804 9.48 CH4 methane 1554 34.4 2828 18.4 1800 3.13 C4H10 butane 1543 33.6 2823 18.3 1801 4.03 C3H8 propane 1542 33.0 2816 18.0 1825 5.66 C2H6 ethane 1592 33.5 2926 18.4 1825 6.54 C2H4 ethylene 1674 34.8 3113 19.1 1867 7.75 C2H2 acetylene 1532 27.7 2949 15.6 1971 29.6 H2 hydrogen Fuel –air mixtures TvN [K] PvN [bar] TCJ [K] PCJ [bar] UCJ [m/s] % vol. Fuel

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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CJ Detonation

  • Velocity
  • Pressure
  • Temperature

Are simple to calcutale from equilibrium codes: NASA STANJAN SUPERSTATE

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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ZND Detonation

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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ZND Detonation

Calculated values of the physical parameters of ZND model for various hydrogen and propane detonations (Glassman I., Combustion, 1996)

1.84 5.57 1.00 ρ/ρ1 3680 1773 298 T [K] 19 33 1 P [bar] 1589 524 2920 U [m/s] 1.00 0.40 5.29 M H2 – O2 (Φ Φ Φ Φ = 1.1) 1.80 5.39 1.00 ρ/ρ1 2976 1546 298 T [K] 16 28 1 P [bar] 1129 377 2033 U [m/s] 1.00 0.41 4.86 M H2 – air (Φ Φ Φ Φ = 1.2) 2 1’ 1

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Detonation wave structure

2H2+O2+17Ar at 20kPa (Austin&Shepherd)

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Fuel-air mixtures

Detonation cell size

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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hydrogen-air mixtures

Detonation cell size

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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hydrogen-oxygen mixtures

Detonation cell size

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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  • propagation limit:

dtube > df df = λ/π

  • critical tube diameter for diffraction: dtube > dc

Tube: dc= 13 λ Square channel: lc = 10 λ

  • Critical energy for direct initiation: E > Ec

3 2

430 λ ρ

CJ c

U E =

Detonation limits

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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  • single spin (head)

Detonation propagation limits

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Single spin detonation

Experimental soot traces for CH4 + 2O2 mixture at P0 = 50mbar. CH4/O2 spinning detonation simulation

Source: F.Virot et al., 21st ICDERS, Poitiers, 2007

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Single spin detonation

Source: N.Tsuboi et al., 21st ICDERS, Poitiers, 2007

Comparison of pressure contours on the wall

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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  • propagation limit

Detonation limits

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Minimum tube diameter

at28a: T = 298 K, P = 100 kPa, Φ = 1, 80-90% Ar; at28b: T = 298 K, P = 100 kPa, Φ = 1, 70-80% He; at28c: T = 298 K, P = 100 kPa, Φ = 1, 55-75% N2; at28d: T = 298 K, P = 100 kPa, Φ = 1, 90% Ar; at28e: T = 298 K, P = 100 kPa, Φ = 1, 86% He

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Detonation propagation geometries

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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  • critical tube diameter

for diffraction to unconfined space

Detonation critical tube diameter

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Critical tube diameter

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Critical tube diameter

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Critical mixture layer

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Critical energy for direct initiation

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Detonation database

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Deflagration and detonation pressure

a) Slow deflagration; b) fast deflagration; c) overdriven detonation DDT; d) CJ detonation

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Transition distance to DDT

  • Combustible mixture (chemistry and thermodynamics)
  • Tube diameter – for hydrogen-air in smooth tube:
  • 8 m in 50 mm tube
  • 30 m in 400 mm tube
  • Ignition source
  • Obstacles, wall roughness
  • Initial conditions
  • ???

Depends on:

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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DDT in tube with obstacles

(Lee, 1986)

Flame velocity versus fuel concentration for H2-air mixtures 10 m long tubes of 5 cm, 15 cm and 30 cm in internal diameter with

  • bstacles (orifice plates).

BR = 1 - d2/D2 – blockage ratio d - orifice diameter D - tube diameter

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Regimes of flame propagation in tubes with obstacles

  • quenching regime - flame fails to propagate,
  • subsonic regime - flame is traveling at a speed that is slower than

the sound speed of the combustion products,

  • choked regime (CJ Deflagration) - flame speed is comparable with

the sound speed of the combustion products,

  • quasi-detonation regime - velocity between the sonic and

Chapman-Jouguet (CJ) velocity,

  • CJ detonation regime - velocity is equal to the CJ detonation

velocity

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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DDT in tube with obstacles

(Teodorczyk, et al..1988)

Stoichiometric hydrogen-oxygen Pressure 20-150 torr Ignition by exploding wire

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Regimes of flame propagation leading to DDT

Propagation speeds of flames and detonations along the tube versus ratio of distance, x, to tube diameter, D (hydrogen–air mixtures).

Source: S.Dorofeev et al., Journal of Loss Prevention in the Process Industries 14 (2001) 583–589

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Flame acceleration and DDT in

  • bstructed channels

2 4 6 8 10 12 14 16 18

%CH4

54 174 520 100 200 300 400 500

D, mm

FAST SLOW SLOW UFL = 16.8%CH4 LFL = 4.6%CH4 DDT

20 40 60 80

%H2

80 174 350 520 100 200 300 400 500

D, mm

FAST SLOW SLOW

UFL = 76%H2 LFL = 4%H2

FAST DDT

d D=174 mm

Obstacle Gauge port Ignition circuit Gas filling line

S=D L=11.5 m

(Courtesy of M.Kuznetzov)

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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DDT limits in obstructed channels (H2-air)

(Courtesy of S.Dorofeev)

α − = 1

1

L L

Geometrical size

2

1

H L L + =

where

L – distance between obstacles H – channel height h – obstacle height

H h − = 1 α

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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Run-up distance for DDT in

  • bstructed channels

(Courtesy of S.Dorofeev)

In tubes at 0.1 MPa, H2-air

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Second European Summer School on Hydrogen Safety, Belfast, 30 July-8 August 2007 by Andrzej Teodorczyk

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DDT simulations

V.Gamezo et al., 31st Symposium International on Combustion, Heidelberg 2006

  • stoichiometric hydrogen-air mixture at 0.1 MPa
  • Reactive Navier-Stokes equations with one-step Arrhenius kinetics
  • 2D channel with obstacles: length = 2m; height H = 1, 2, 4, 8 cm
  • Grid: 0.02 mm (min)

H 2H H/2