Examination of the Low-Temperature Heat Release Occurrence in SI Engine

Transcription

1 Examination of the Low-Temperature Heat Release Occurrence in SI Engine University of Zagreb Faculty of Mechanical Engineering and Naval Architecture Laboratory for IC Engines and Motor Vehicles Mladen Božić, Ante Vučetić, Darko Kozarac, Zoran Lulić 49. GOMA Symposium Fuels October 2016

2 Contents Experimental IC Engine setup Indicating Knock Heat release Data analysis Results Conclusion 2

3 This work represents part of the PhD thesis: Introduction Influence of the Exhaust Gas Recirculation on the Occurrence of Knock in Modern SI Engines Exhaust Gas Recirculation (EGR) is a nitrogen oxide (NO X ) emissions reduction technique used in SI engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O 2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. Knock occurrence abnormal combustion 3

4 Introduction Correlations: RPM EGR p LTHR q e - Engine Speed - Exhaust Gas Recirculation - In-Cylinder pressure - Low Temperature Heat Release - In-Cylinder temperature - Compression ratio 4

5 Experimental IC Engine setup Control room Pressure regulator 5

6 Testbed Experimental Engine Experimental IC Engine Testbed Control cabinet 6

7 Experimental IC Engine setup AC Dyno IC Engine 7

8 Indicating Crankshaft LP11DA 0 10 bar GH14DK bar Knock Normal Combustion Acquisition and processing of fast crank-angle based signals typical for combustion engines. ifile No: 1, 2, 3, 4, 5, 6, 7 8

9 TDC Knock Super Knock Knock Normal combustion Knock in IC SI Engine (Internal Combustion Spark Ignition) is induced by: High compression ratio Low octane number Large flame propagation path Spark advance Boosting of the engine Large engine load Low cooling of the combustion chamber Source : Tomić Rudolf, Model of Knock Phenomenon in Spark Ignition Engine, PhD, FAMENA

10 Heat release calculation First law of thermodynamics U Q W du dq dq du dw dw Heat Internal Energy Work = Heat release - Heat transfer - Crevice losses - Blow-by Heat release per crank angle Experimental setup = pressure and volume as a function of crank angle Source: Bengt Johansson Heat release analysis 10

11 Data analysis Motored? Geometry Inputs_from summary_file.txt Air Input_file Data_shift Cyl_press_shift O 2 N 2 Fuel Heat transfer 18/10/

12 Different Fuels - Spark Sweep Eurosuper 95, A Eurosuper 95, B Eurosuper 98 Eurosuper 100 TDC Late Spark Timing Early Spark Timing 115 work points 300 consecutive cycles 12

13 Coefficient of Variation: Combustion Instability σ IMEP standard deviation over a number of consecutive combustion cycles μ IMEP mean value over a number of consecutive combustion cycles 13

14 LTHR different fuels comparison Low Temperature Heat Release 14

15 LTHR different fuels comparison 15

16 Engine Performace Same Spark Timing 16

17 Indicated Pressure 1300 RPM, 0 CA ATDC (TDC) 300 Cycles Eurosuper 95, A 17

18 Indicated Pressure 1300 RPM, 0 CA ATDC (TDC) 300 Cycles Eurosuper 95, B 18

19 Indicated Pressure 1300 RPM, 0 CA ATDC (TDC) 300 Cycles Eurosuper 98 19

20 Indicated Pressure 1300 RPM, 0 CA ATDC (TDC) 300 Cycles Eurosuper

21 Emission of Hydrocarbons 21

22 Emission of Carbon Monoxide 22

23 Emission of Carbon Dioxide 23

24 Max In-Cyl. Temp. Emission of Nitrous Oxides 2338 K 2266 K 2255 K 2208 K 24

25 Indicated Specific Fuel Consumption 25

26 Conclusion In this research higher octane number fuels reach more IMEP Higher level of LTHR is observed at low octane fuel Lower octane fuel results in Knock induced by LTHR Fuels tested in this study show the expected emission values of HC, CO, CO 2 and NO X High Octane fuels reach lower fuel consumption 26

27 Thank you for your attention! Questions, comments, Acknowledgment The study was performed within the FMENA project Experimental Research, Optimization and Characterization of piston engine operation with DUal-Fuel COmbustion - DUFCOROC IP funded by the Croatian Science Foundation. This help is gratefully appreciated. mladen.bozic@fsb.hr 27