Ammonia Combus,on in spark igni,on engine condi,ons

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1 Ammonia Combus,on in spark igni,on engine condi,ons Catherine Duynslaegher, Hervé Jeanmart, Jacques Vandooren, Université catholique de Louvain, Belgium

2 Introduc,on Search for alternatives to fossil fuels Oxygenated fuels, biodiesel and hydrogen have been put forward BUT : Implementing a global hydrogen-based economy is at present a nonfeasible approach unless a suitable storage medium can be found use of ammonia in a modified spark ignition engine ( = hydrogen vector ) The successful application of ammonia as an alternative transportation fuel should be grounded on a detailed understanding of its combustion characteristics 2/26

3 Outline Combus,on at low pressure Burning velocity Combus,on in a spark igni,on engine 3/26

4 Outline Combus,on at low pressure Burning velocity Combus,on in a spark igni,on engine 4/26

5 Combus,on at low pressure Kinetic mechanisms used to simulate ammonia combustion are originated from hydrocarbon models taking into account nitrogenated species Elaborate a new mechanism more specific for ammonia and validated at several conditions of pressure, temperature and equivalence ratio Flame structures at low pressure 5/26

6 Experimental device Flat flame Mass spectrum device Gas feeding Flat flame burner Ini1al H2 % Combustion chamber Quartz nozzle Chopper Equivalence Ra1o Pressure 6/26

7 Flame structure Mole fraction NH3 (ф = 1) 0.25 NH3 (ф = 0.9) NH3 (ф = 1.1) NO x 10 (ф = 1) NO x 10 (ф = 0.9) NO x 10 (ф = 1.1) Distance from burner (mm) Symbols : Experience Lines : Numerical simula,on 7/26

8 Reac,on pathways 80 reactions 19 chemical species NH3 NH2 HNO NH N2H2 N NNH NO2 NO N2O N2 8/26

9 Outline Combus,on at low pressure Burning velocity Combus,on in a spark igni,on engine 9/26

10 Burning velocity Igni,on of the mixture at the open end of a tube and propaga,on of the flame toward the closed end. Burning velocity obtained from the equa,on of mass conserva,on for the unburnt gas a = area of tube sec,on Af = area of flame surface Ss = flame speed Su= laminar burning velocity 10/26

11 Experimental measure Numerical recons,tu,on 11/26

12 Effect of dilu,on varia,on 12/26

13 Effect of equivalence ra,o varia,on 13/26

14 Outline Combus,on at low pressure Burning velocity Combus,on in a spark igni,on engine 14/26

Experimental device GC : H2 Measure of engine

Igni1on Engine Monocylinder research engine Vc

FTUV : NH3 NO NO2 Balance to obtain N2, H2O, O2

the impact of spark advance, compression ra,o,

15 Experimental device GC : H2 Measure of engine performances Ammonia flowmeter Air Spark Igni1on Engine Monocylinder research engine Vc : 814 cm³ Stroke : mm Cylinder Bore : mm Intake pressure : 1 bar Intake temperature : C Engine speed : 1500 RPM FTUV : NH3 NO NO2 Balance to obtain N2, H2O, O2 Exhaust Cooling unit Heat exchanger Study of the impact of spark advance, compression ra,o, equivalence ra,o on the engine performances and on the exhaust 15/26 gases

16 Effect of a CR Varia,on Ammonia has a high octane ra,ng ( 130) High CR can be applied to improve engine performances Experimental condi,ons: Compression ra,os 15 ; 17 and 19 (19 = max engine capaci,es ; 15 =minimum to allow correct NH3 combus,on) Spark advance : 30 BTDC Equivalence ra,o : 1 16/26

17 C.R. Torque [Nm] RPM bmep [kpa] η eff C.R. N2 (%) H2O (%) O2 (%) NH3 (%) NO (ppm) NO2 (ppm) H2 (ppm) /26

18 18/26

19 Effect of a spark advance varia,on Ammonia flame has a low speed High spark advances must be applied to keep engine performances Experimental condi,ons: Spark advance from 16 to 30 (30 = max to avoid knocking ; 16 =minimum to allow correct NH3 combus,on) Compression ra,o : 18 Equivalence ra,o : 1 19/26

20 Spark advance [ ] Torque [Nm] RPM bmep [kpa] η eff Spark advance [ ] N2 (%) H2O (%) O2 (%) NH3 (%) NO (ppm) NO2 (ppm) H2 (ppm) /26

21 21/26

22 Effect of an equivalence ra,o varia,on Important impact of ф on the NOx forma,on especially around stoichiometric condi,ons Experimental condi,ons: Equivalence ra,os from 0.8 to 1.1 (Flammability limits at STP from 0.6 to 1.3) Spark advance : 30 BTDC Compression ra,o : 17 22/26

23 ф Torque [Nm] RPM bmep [kpa] η eff Ф N2 (%) H2O (%) O2 (%) NH3 (%) NO (ppm) NO2 (ppm) H2 (ppm) /26

24 24/26

25 Conclusion Ammonia combus,on characteris,cs Important impact of the equivalence ra,o on the nitrogen oxides forma,on Ammonia flame has a low speed Op,mal SI engine combus,on condi,ons Compression ra,o : 17 Spark advance : 20 BTDC Equivalence ra,o : slightly above 1 25/26

26 Thank You 26/26

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