1 Olivier LE CORRE Frédéric PIROTAIS I.N.P.G. - FRANCE Ox Emissions Reduction of a Natural Gas SI Engine under Lean Conditions: Comparison of the EGR and RGR concepts N E.M.N. - FRANCE Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany

2 INTRODUCTION CHP fuelled by NG - good thermal efficiency - smaller impact on global warning high H/C ratio limits CO2 emission Sogaard et al. Nevertheless - high emission level of UHC Main advantages of a hydrocarbon and hydrogen blend - increases thermal efficiency - reduces UHC, CO, CO2 emissions Tsolakis et Megaritis Nevertheless - NOx emissions raising

3 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Hydrogen: fuel for the future? Unfortunately Hydrogen production and storage are difficult Hoekstra Idea : in-situ fuels reforming Zheng et al. INTRODUCTION

4 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany RGR Concept

5 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Table of contents 1/ SI engine Thermodynamic model Test bench 2/ Reformer Model Bibliography 3/ Feedback loop 4/ Conclusion and perspectives

6 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Table of contents 1/ SI engine Thermodynamic model Test bench 2/ Reformer Model Bibliography 3/ Feedback loop 4/ Conclusion and perspectives

7 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Two-zone thermodynamic model - fresh and burnt gases - an uniform in-cylinder pressure - both leakage and blow-by are neglected - burnt mass fraction, see Chelma - laminar speed of blend, see Shahad Al-Janabi and Sadi Al-Baghadi - wall heat transfer, see Hohenberg

8 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Test Bench

9 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany

10 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany S.I. engine Good agreements between numeric simulations and experimental tests

11 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Table of contents 1/ SI engine Thermodynamic model Test bench 2/ Reformer Model Bibliography 3/ Feedback loop 4/ Conclusion and perspectives

12 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Reformer : model at equilibrium See Xu and Froment

13 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Reformer : plug flow

14 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Reformer results comparison with bibliography Allenby

15 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Table of contents 1/ SI engine Thermodynamic model Test bench 2/ Reformer Model Bibliography 3/ Feedback loop 4/ Conclusion and perspectives

16 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Feedback loop

17 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Table of contents 1/ SI engine Thermodynamic model Test bench 2/ Reformer Model Bibliography 3/ Feedback loop 4/ Conclusion and perspectives

18 Spring Technical Conference, May 8 – 10, 2006, Aachen, Germany Conclusion and Perspectives Blend of Reformed Gas Recirculation and Natural Gas : an opportunity to optimise the CHP engines Nevertheless, under very lean conditions, misfire occures and leads cycle to cycle dispersions. On one hand, hydrogen improves flame propagation BUT, on the other hand very lean conditions reduce it.