Performance and Emission Characteristics of a Miller Cycle Engine

Öz

In this study, intake and exhaust cams were designed to perform the late intake valve closing (LIVC) Miller cycle operation using spline functions in a single-cylinder, four-stroke, spark-ignition engine. A special camshaft was manufactured and adapted to the engine to adjust valve opening and closing timings. The experiments were conducted at two different LIVC timing and the results were compared with Otto cycle. The tests were conducted at 1700-3200 rpm engine speed range at wide open throttle (WOT). In the experiments, the variation of brake torque, power output, specific fuel consumption (SFC), thermal efficiency, HC, CO, NOx emissions and exhaust gas temperature versus engine speed were investigated. More power output was obtained with Otto cycle than Miller cycles for all engine speeds. Brake torque and engine power decreased by 5.24%, and 1.17% respectively with MA cycle (Miller cycle A) compared to Otto cycle at 2600 rpm engine speed. Thermal efficiency increased by 1.29%, while the SFC decreased 2.08 % with Otto cycle in comparison with MA cycle at maximum brake torque speed. HC and CO increased by 6.48 % and 11.66% respectively with MA cycle compared to Otto cycle at the same operation condition. NOx decreased up to 7.79% with MA cycle compared to Otto cycle due to the lower exhaust gas temperature at maximum brake torque speed of 2600 rpm.

Anahtar Kelimeler

• Miller cycle,cam design,spline functions,engine performance,exhaust emissions

Kaynakça

1. Wang, Y., Lin, L., Zeng, S., Huang, J., Roskilly, A.P., He, Y., Huang, X., Li, S., Application of the Miller cycle to reduce NOx emissions from petrol engines. Applied Energy, 2008;85(6), 463-474.
2. Wang, Y., Lin, L., Roskilly, A.P., Zeng, S., Huang, J., He, Y., Huang, X., Huang, H., Wei, H., Li, S., Yang, J. (2007). An analytic study of applying Miller cycle to reduce NOx emission from petrol engine. Applied Thermal Engineering, 2007; 27(11-12), 1779-1789.
3. Ge, Y., Chen, L., Sun, F., Wu, C., Effects of heat transfer and friction on the performance of an irreversible air-standard Miller cycle. International Communications in Heat and Mass Transfer, 2005; 32(8), 1045-1056.
4. Miller, R.H., Supercharging and internal cooling cycle for high output. Trans ASME, 1947; 69, 453–464.
5. Wu, C., Puzinauskas, P.V., Tsai, J.S., Performance analysis and optimization of a supercharged Miller cycle Otto engine. Applied Thermal Engineering, 2003; 23(5), (2003), 511-521.
6. Miller, R.H., Lieberherr, H.U., The Miller supercharging system for Diesel and gas engines operating characteristics, CIMAC, 1957. In: Proceedings of the 4th International Congress on Combustion Engines, Zurich. June 1957; 15-22, 787-803.
7. Simmons, L.D. Altering the spark-ignited internal combustion engine cycle, thermodynamics and the design, analysis, and improvement of energy systems, ASME AES, 1994; 33, 205-210.
8. Zhao, Y., Chen, j., Performance analysis of an irreversible miller heat engine and its optimum criteria. Applied Thermal Engineering, 2007; 27(11-12), 2051-2058.

9. Lin, J.C., Hou, S.S. Performance analysis of an air-standard Miller cycle with considerations of heat loss as a percentage of fuel’s energy, friction and variable specific heats of working fluid. International Journal of Thermal Sciences, 2008; 47(2), 182-191.
10. Mikalsen, R., Wang, Y.D., Roskilly, A.P. A comparison of Miller and Otto cycle natural gas engines for small scale CHP applications. Applied Energy, 2009; 86(6), 922-927.
11. Ebrahimi, R., Performance analysis of an irreversible Miller cycle with considerations of relative air–fuel ratio and stroke length. Applied Mathematical Modelling, 2012; 36(9), 4073-4079.
12. J. Martins, J. Ribeiro, S. Teixeira, In-cylinder swirl analysis of different strategies on over-expanded cycles. 20th International Congress of Mechanical Engineering, 2009.
13. Okamoto, K., Zhang, F.R., Shimogata, S., Shoji, F., Development of a late intake valve closing (LIVC) Miller cycle for stationary natural gas engines- effect of EGR utilization, Society of Automotive Engineers Inc., 1997; 972948, 87-99.
14. Tsukida, N., Sakakura, A., Murata, Y., Okamoto, K., Takemoto, T., Development of Miller cycle gas engine for cogeneration. Proceeding of the ASME Advanced Energy Systems Division, 1999;453-457.
15. Ribeiro, B., Martins, J., Direct comparison of an engine working under Otto, Miller and Diesel cycles: thermodynamic analysis and real engine performance. SAE Paper 2007-01-0261, 2007.
16. Lancefield, T., Methley, I., Rase, U., Kuhn, T., The application of variable event valve timing to a modern diesel engine. SAE Paper, 2000-01-1229, 2000.
17. Cinar, C., Sahin, F., Can, Ö., Uyumaz, A., A comparison of performance and exhaust emissions with different valve lift profiles between gasoline and LPG fuels in a SI engine, Applied Thermal Engineering, 2016; 107, 1261-1268.
18. Hsieh, J. F., Design and analysis of cams with three circular-arc profiles. Mechanism and Machine Theory, 2010; 45(6), 955-965.
19. Norton, R. L., Cam design and manufacturing handbook, 67, Industrial Press Inc., 10016-4078, United States of America, 2002.
20. Nguyen, V.T., Kim, D.J., Flexible cam profile synthesis method using smoothing spline curves. Mechanism and Machine Theory, 2007; 42(7), 825-838.
21. Mandal, M., Naskar, T.K., Introduction of control points in splines for synthesis of optimized cam motion program. Mechanism and Machine Theory, 2009; 44(1), 255-271.
22. Karabulut, H., Sarıdemir, S., Comparison of cam profiles obtained via classical spline method for different lifted-valve periods and lifts. Journal of the Faculty of Engineering and Architecture of Gazi University, 2009; 24(3), 509-515.
23. Demirci, O.K., Application of Miller Cycle in a Spark Ignition Engine and the Investigation of Performance and Emission Characteristics, M.Sc. Thesis, Gazi University Institute of Science and Technology, 2013.
24. Eyidogan, M., Özsezen, A.N., Canakci, M., Turkcan, A., Impact of alcohol-gasoline fuel blends on the performance and combustion characteristics of an SI engine. Fuel, 2010; 89(10), 2713-2720.