Abstract




 
   

IJE TRANSACTIONS B: Applications Vol. 28, No. 2 (February 2015) 251-260   

downloaded Downloaded: 163   viewed Viewed: 2231

  AN EXPERIMENTAL AND THEORETICAL STUDY OF THE EFFECTS OF EXCESS AIR RATIO AND WASTE GATE OPENING PRESSURE THRESHOLD ON NOX EMISSION AND PERFORMANCE IN A TURBOCHARGED CNG SI ENGINE
 
S. Kharazmi, A. H. Benisi and A. Mozafari
 
( Received: July 06, 2014 – Accepted: November 13, 2014 )
 
 

Abstract    Turbocharged CNG engines produce high NOx emission due to the fuel type and high combustion temperature. In this research, the effects of lean-burn and waste gate opening pressure threshold on NOx emission are studied theoretically and experimentally at WOT condition as well as 13-mode ECE-R49 test cycle. A code is developed in MATLAB environment for predicting engine NOx and the results are validated with the research experiments. Simulations show that NOx increases by increase of excess air ratio and reaches at most to 2486ppm at excess air ratio of 1.1 and then decreases. It is also experimentally found that changing waste gate opening pressure threshold from 165mmHg to 200 and 265mmHg decreases total bsNOx at a rate of 6% and 12% respectively. Increase of the threshold to 323mmHg increases total bsNOx. Therefore, to minimize the cycle bsNOx, the threshold of 265mmHg is the optimum threshold for the engine between the four pressure thresholds experimented.

 

Keywords    Turbocharged CNG SI engine, NOx emission, ECE-R49 test cycle, lean-burn, waste gated turbocharger

 

چکیده    در این پژوهش، اثرات نسبت هوای اضافی و فشار آستانه بازشدگی دریچه هدرروی توربوشارژر بر آلایندگی NOx و عملکرد یک موتور گازسوز توربوچارجری بصورت تجربی در سیکل آزمون 13 نقطه ای ECE-R49 ارزیابی می­شوند. یک کد رایانه ای در محیط نرم افزار MATLAB ایجاد می­شود تا NOx و عملکرد موتور را پیش­بینی کند و نتایج آن با نتایج تجربی همین پژوهش ارزیابی می شوند. اثر نسبت هوای اضافی موتور بر آلایندگی NOx، توان و مصرف مخصوص سوخت اندیکاتوری بصورت مطالعه پارامتری بوسیله کد رایانه ای این پژوهش ارزیابی می شود. آلایندگی NOx بارکامل در نسبت هوای اضافی 1/1 بیشینه است. مطالعه پارامتری نشان می دهد که افزایش نسبت هوای اضافی بمیزان %20، توان اندیکاتوری بیشینه را %9 کاهش و حداقل مصرف مخصوص سوخت اندیکاتوری را %7 بهبود می دهد. نتایج آزمایشها نشان می دهند با افزایش فشار آستانه باز شدن دریچه هدررو، توان ترمزی موتور بخصوص در دور و بار زیاد، افزایش می یابد. بصورت آزمایشگاهی دریافته می شود آلایندگی NOx مخصوص ترمزی کل با تغییر فشار آستانه بازشدگی دریچه هدررو از mmHg165 به 200 و mmHg265، به ترتیب6 و %12 کاهش می­یابند. افزایش این آستانه فشار به mmHg323، NOx مخصوص ترمزی کل را افزایش می دهد. در نتیجه بمنظور کمینه کردن NOx مخصوص ترمزی کل، فشار آستانه mmHg265، آستانه بهینه این موتور بین چهار حالت مورد آزمون می باشد.

References   

 

1.     Korakianitis, T., Namasivayam, A. and Crookes, R., "Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions", Progress in Energy and Combustion Science,  Vol. 37, No. 1, (2011), 89-112.

2.     Kharazmi Sh, Mozafari A and Hajilouy-Benisi A., "Simulation and experimental investigation of performance and emissions of a turbocharged lean-burn natural gas engine considering thermal boundary layer", Scientia Iranica Journal, Transaction B: Mechanical Engineering,  Vol. 21, No. 4, (2014), 1424-1439.

3.     Ibrahim, A. and Bari, S., "Optimization of a natural gas SI engine employing egr strategy using a two-zone combustion model", Fuel,  Vol. 87, No. 10, (2008), 1824-1834.

4.     Kharazmi Sh, Mozafari A  and Hajilouy-Benisi A., "Simulating turbulence and combustion in cng turbocharged engine considering cylinder thermal boundary layer and EGR", Proceedings of the Seventh International Conference on Internal Combustion Engines, Olympic Hotel, Tehran, Iran, November 8-10, ICICE-7-0176, (2011).

5.     Kharazmi, S., Hajilouy-Benisi, A. and Mozafari, A.A., "Computer simulation of turbocharged aftercooled gasoline engine", in ASME 8th Biennial Conference on Engineering Systems Design and Analysis, American Society of Mechanical Engineers, (2006), 487-495.

6.     Shamsderakhshan, M. and Kharazmi, S., Turbocharger matching and assessments of turbocharger effect on a diesel engine based on one-dimensional simulation, (2014), SAE Technical Paper.

7.     Cho, H.M. and He, B.-Q., "Spark ignition natural gas engines—a review", Energy Conversion and Management,  Vol. 48, No. 2, (2007), 608-618.

8.     Ibrahim, A. and Bari, S., "An experimental investigation on the use of EGR in a supercharged natural gas SI engine", Fuel,  Vol. 89, No. 7, (2010), 1721-1730.

9.     Ibrahim, A. and Bari, S., "A comparison between EGR and lean-burn strategies employed in a natural gas SI engine using a two-zone combustion model", Energy Conversion and Management,  Vol. 50, No. 12, (2009), 3129-3139.

10.   Mohebbi A., Jafarmadar S., Pashae J. and Shirnezhad M., "Experimental studying of the effect of egr distribution on the combustion, emissions and performance in a turbocharged di diesel engine", International Journal of Engineering- Transactions A: Basics,  Vol. 26, No. 1, (2013), 73-82.

11.   Jafarmadar, S. and Pashae, J., "Experimental study of the effect of castor oil biodiesel fuel on performance and emissions of turbocharged DI diesel", International Journal of Engineering-Transactions B: Applications,  Vol. 26, No. 8, (2013), 905-912.

12.   Ebrahimi, R. and Mercier, M., "Experimental study of performance of spark ignition engine with gasoline and natural gas", International Journal of Engineering,  Vol. 24, No., (2010), 65-74.

13.   Bhatt K., "Potential for meeting the eu new passenger car CO2 emissions target", MSc Thesis, MIT University, USA, (2010),  .

14.   Martyr AJ and Plint MA., "Engine testing theory and practice”, 3rd ed. Elsevier ltd", (2007).

15.   Hohenberg, G.F., Advanced approaches for heat transfer calculations, (1979), SAE Technical paper.

16.   Lounici, M.S., Loubar, K., Balistrou, M. and Tazerout, M., "Investigation on heat transfer evaluation for a more efficient two-zone combustion model in the case of natural gas si engines", Applied Thermal Engineering,  Vol. 31, No. 2, (2011), 319-328.

17.   Lammle, C., "Numerical and experimental study of flame propagation and knock in a compressed natural gas engine,  Vol. 68,  (2006).

18.   Gu, X., Haq, M., Lawes, M. and Woolley, R., "Laminar burning velocity and markstein lengths of methane–air mixtures", Combustion and Flame,  Vol. 121, No. 1, (2000), 41-58.

19.   Liao, S., Jiang, D. and Cheng, Q., "Determination of laminar burning velocities for natural gas", Fuel,  Vol. 83, No. 9, (2004), 1247-1250.

20.   Elia, M., Ulinski, M. and Metghalchi, M., "Laminar burning velocity of methane–air–diluent mixtures", Journal of Engineering for Gas Turbines and Power,  Vol. 123, No. 1, (2001), 190-196.

21.   Rahim, F., Elia, M., Ulinski, M. and Metghalchi, M., "Burning velocity measurements of methane-oxygen-argon mixtures and an application to extend methane-air burning velocity measurements", International Journal of Engine Research,  Vol. 3, No. 2, (2002), 81-92.

22.   Gulder, O.L., "Turbulent premixed flame propagation models for different combustion regimes", in Symposium (International) on Combustion, Elsevier. Vol. 23, (1991), 743-750.

23.   Heywood, J.B., "Internal combustion engine fundamentals, McGraw-hill New York,  Vol. 930,  (1988).

24.   Kesgin, U., "Study on prediction of the effects of design and operating parameters on NOx emissions from a leanburn natural gas engine", Energy Conversion and Management,  Vol. 44, No. 6, (2003), 907-921.   





International Journal of Engineering
E-mail: office@ije.ir
Web Site: http://www.ije.ir