Farid C. Christo13.211.155.234/wp-content/uploads/2019/12/Farid-Christo.pdf · C05 0 30 4×10-3 45 0 45 0.30 C06 1×10-3 30 4×10-3 45 0 45 0.24 ... Mole Fraction O 2 (%) CO 2 (%)

Farid C. ChristoPhD (Sydney Uni) , MSc (AE), BSc (AE), MIAust

Combustion III

Combustion III

Hydrogen-based Flameless Gas Turbine Combustor

Farid C. Christo1, Gabrian A.F. Balelang1, Yeshayahou Levy2 & Mário Costa3

1School of Engineering, Flow, Aerosols & Thermal Energy (FATE) Group, Deakin University, Geelong, VIC 3320, Australia.

2Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Israel.

3IDMEC, Mechanical Engineering Department, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal

3

Conventional versus Flameless Combustion

G G Szego, B B Dally, F.C. Christo, G J Nathan

◼ Reduced NOx emissions.

◼ Nearly uniform thermal field.

◼ Increased net radiation transfer.

◼ Reduced noise levels.

(Milan & Saponaro 2001)Courtesy: Oil & Gas Portal

Diffusion Flame

Diffusion Flame

Flameless Combustion

Flameless Combustion

1 2 3

4 5 6

4

4

Challenges for Flameless Combustion in GT Engines

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary

48 2 1 0Recirculation Ratio

% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition Temp

Norm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

300

600

900

1200

1500

1800

2100

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 300 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary


% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition Temp

Norm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

Oxygen Content at the Recirculation Zone. I- before combustion, II-after combustion

5

T

X

400°

C

2200°

C

1300°C

1500°C

Low NOx production

flameless

conventional

NOx FORMATION REGION

The Concept of Flameless GT Combustor

Rolls-Royce Nene Turbojet https://commons.wikimedia.org/w/index.php?curid=18712637

6

m2 flow of preheated (355°C) air, injected via 14xΦ5mm diameter holes.

m1 flow of preheated (355°C) air, injected via 14xΦ5mm diameter holes.

m3 flow Secondary preheated air (355°C), injected via 19xΦ1mm diameter holes.

Fuel (NG) 4.92x10-5 kg/s, injected via 38xΦ0.5mm diameter holes, arranged in two (19 holes) staggered rows.

Experimental Combustor

7

Flow Configurations & CFD Model Parameters

Config.Air-1 (kg/s)

a (°)Air-2 (kg/s)

β (°)Air-3 (kg/s)

γ (°) Φg

C01 3×10-3 30 3×10-3 60 0 45 0.21C02 3×10-3 30 1×10-3 60 0 45 0.31C03 1×10-3 30 3×10-3 60 0 45 0.31C04 0 30 4×10-3 60 0 45 0.30C05 0 30 4×10-3 45 0 45 0.30C06 1×10-3 30 4×10-3 45 0 45 0.24C07 1×10-3 30 4×10-3 45 1.7×10-3 45 0.18C08 1×10-3 30 4×10-3 45 3.4×10-3 45 0.15C09 1×10-3 30 5×10-3 45 0 45 0.21C10 0 30 5×10-3 45 0 45 0.25C11 0 30 7×10-3 45 0 45 0.19

(b)

Exhaust Gases

Fuel

Air-1α

Air-3γ

Air-2

β

❑ 3D steady-State 60°-Segment model,

❑ Turbulence model; SST κ-ω.

❑ Chemistry; CH4 kinetics; global 2-step, 16 species & 45 reactions, and GRI 3.0 mechanism.

❑ Turbulence- Chemistry Interaction model; EDM, flamelet, and EDC

❑Thermal Radiation : DO model

❑ Pressure: 1atm.

Firing Rate: 3.8 kW & 2.4kW

Air & Fuel Injectors – Geometry & Flow Rates (Methane fuel)

❑ α =30°, β=45° and γ=45°.

❑ 85% of total air via Air-3.

8

Effect of Chemistry & Turbulence-Chemistry Interaction (TCI) Models

ModelTemperature

(°C)

Mole Fraction

O2 (%) CO2 (%)NOx (ppmv) 15% O2

Dry BasisEDM - 2 Steps 1330 11.08 4.41 35.84Flamelet - Smooke 1350 12.36 3.91 12.56Flamelet - GRI30 1322 11.31 4.36 5.79EDC-Smooke 1370 10.71 4.53 2.205Experiment* 1300 11.50 4.95 0.6* The overall uncertainty in the measurements is ±3%.

(methane fuel)

❑ Turbulence-Chemistry Interaction model has more effect of predictions accuracy than the chemical kinetics model.

❑ For design & optimisation purposes, the Flamelet-GRI3.0 (or a suitable mechanism for other fuels) TCI is used.

9

Visual & Numerical Model Validation

0

2

4

6

8

10

12

14

16

350 550 750 950 1150 1350 1550 1750 1950 2150

Pe

rce

nta

ge C

ou

nt

Combustor Temperature (⁰C)

Flameless combustion mode

Diffusion flame

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary


% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition Temp

Norm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

300

600

900

1200

1500

1800

2100

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 300 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary


% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition Temp

Norm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

10

Hydrogen-based Fuel Models

FuelCombustion

Model

Kinetics ModelReference

Species Reactions

Methane Flamelet 16 49 (Smooke 1991)

Hydrogen Flamelet 10 21 (ÓConaire 2004)

Ammonia Flamelet 55 277 (Mathieu and Petersen 2015)

2.46 kW, and ∅𝒈 = 𝟎. 𝟒𝟒

11

Temperature & Streamlines

CH4 NH3 H2

12

Model Predictions

Fuel Mole fractions Temperature

(°C)NOx (ppmv)

15%O2 - dry basisO2 (%) H2O (%)CH4 11.31 [11.5] 8.7 [8.7] 1322 [1300] 5.79 [0.6]H2 11.17 16.1 1377 46.41

NH3 10.10 15.91 1268 2.53

Fuel

Air-3 injector Total air Fuel A/F

momentum

ratio

A/F

velocity

ratioVelocity (m/s)

Momentum

[N]

Momentum

[N] Velocity (m/s)

Momentum

[N]

CH4 205.9 0.339 0.339 3.18 0.000156 2173 64.74

H2 171.61 0.236 0.236 10.54 0.000216 1092 16.28

NH3 195.88 0.3075 0.3075 8.05 0.001065 288 24.33

13

Spatial Distribution – Flameless Oxidation Indicators

0

5

10

15

20

25

63

2

68

6

73

9

79

2

84

6

89

9

95

3

10

06

10

59

111

3

11

66

12

20

12

73

13

26

13

80

14

33

14

87

15

40

15

93

16

47

17

00

17

54

%

of flu

id d

om

ain

Temperature (C)

CH4 H2 NH3

0

2

4

6

8

10

12

14

16

0.0

0

0.0

1

0.0

2

0.0

3

0.0

4

0.0

4

0.0

5

0.0

6

0.0

7

0.0

8

0.0

9

0.0

9

0.1

0

0.1

1

0.1

2

0.1

3

0.1

4

0.1

4

0.1

5

0.1

6

0.1

7

0.1

8

0.1

9

0.2

0

0.2

0

% o

f flu

id d

om

ain

O2 Mole Fraction

CH4 H2 NH3

14

Spatial Distribution – Flameless Oxidation Indicators

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary


% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition TempN

orm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

300

600

900

1200

1500

1800

2100

300

600

900

1200

1500

1800

2100

0 3 6 9 12 15 18 21 24 27 300 3 6 9 12 15 18 21 24 27 30

Lif

ted

fla

mes

Hot

Fla

mes

Non Combustible

zone

Ignition Boundary


% Dilutants (N2+CO2+H2O)100 97 95 92 88 85 82 79 76 73 70

%O2 in reactants

Tem

p.

of

Rea

cta

nts

(K

)

Auto Ignition TempN

orm

al

Co

mb

usti

on

Flameless

Combustion

16 0.5

Oxy-r

ich F

lam

es

Oxygen Content at the Recirculation Zone. I- before combustion, II-after combustion

15

CONCLUDING REMARKS

• It has been shown that using the splitting ratio of combustion air among the three inlets that were originally optimised for methane, is also effective for the hydrogen-based fuels, yielding similar spatial temperature distribution and flow structures.

• Low-NOx emission from the hydrogen and ammonia of 46 ppmv and 2.5 ppmv, (corrected to 15%O2 dry basis) respectively, has been achieved.

• The gas temperature and oxygen concentration in the combustor are in the range of 1200°C-1500°C, and 8%-12% (vol.), respectively. These ranges and the low-NOx emissions provide solid evidence that homogenous mixing and reaction of the fuel, air, and combustion product has been achieved.

• This study has provided a proof-of-concept of hydrogen-based flameless GT combustor. Further reduction in NOx emission is possible by optimising the design of the combustor, which is currently underway.

16

ONGOING PROGRESS – PRELIMINARY RESULTS

• To further reduce NOx emission, a study is currently underway to optimise the design (the size, shape and layout) of the Air3 injectors.

• The performance of GT combustor is also being evaluated at various operating pressures 1-25 bars.

17

Temperature Contours

1 Bar 5 Bar 10 Bar

15 Bar 20 Bar 25 Bar

Pressure Effect Analysis

18

Re-design of Air3 Injectors

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25

Ou

tle

t N

Ox

pp

mv (

co

rre

cte

d -

15

%O

2 -

dry

b

asis

)

Combustion chamber pressure (atm)

Current Design

New Design

MultiRow Design

19

[email protected]

Thank You

20

mailto:[email protected]

Documents

Farid C. Christo13.211.155.234/wp-content/uploads/2019/12/Farid-Christo.pdf · C05 0 30 4×10-3 45 0 45 0.30 C06 1×10-3 30 4×10-3 45 0 45 0.24 ... Mole Fraction O 2 (%) CO 2 (%)