Energy Analysis of Two Stroke Engines with a Quasi-Realistic Thermodynamic Model Approach
Özet
This chapter presents a modified finite-time thermodynamic modeling approach for the energy analysis of two-stroke spark-ignition engines. Historically developed alongside other internal combustion engines, two-stroke engines complete intake, compression, expansion, and exhaust processes in a single crank revolution by utilizing both sides of the piston and gas exchange ports, offering compact structures for applications like handheld agricultural tools and generators. To bridge the gap between overly simplified ideal Otto cycles and highly complex three-dimensional numerical simulations, a semi-realistic thermodynamic model is established. This framework incorporates realistic operational factors, including friction losses calculated from mean piston speed, heat transfer modeled via Newton’s law of cooling, compression and expansion irreversibilities, temperature-dependent specific heat capacities, and a realistic fuel-air-residual gas working mixture. Furthermore, the exhaust process is evaluated in two distinct stages, treating the initial exhaust blowdown as an isentropic process. Quantitative design relationships are derived to evaluate how key geometrical parameters—such as the geometric compression ratio, exhaust port opening angle, stroke-to-bore ratio, and connecting rod-to-crank ratio—directly govern the effective compression ratio, volumetric efficiency, and overall engine dimensions. Ultimately, this innovative model provides a practical yet realistic thermodynamic tool for performance estimation and parametric design optimization of two-stroke engines.
Referanslar
Pulkrabek, W. W. (2004). Engineering fundamentals of the internal combustion engine.
Van Basshuysen, R., & Schäfer, F. (2004). Internal combustion engine handbook-basics, components, systems and perspectives (Vol. 345).
Stone, R. (1999). Introduction to internal combustion engines (Vol. 3). London: Macmillan.
Blair, G. P. (1990). Two-Stroke Engines. Society of Automobile Engineering.
Heywood, J. B., & Sher, E. (2017). The two-stroke cycle engine: its development, operation, and design. Routledge.
Blair, G. P. (1999). Design and simulation of four-stroke engines (Vol. 186). SAE Technical Paper.
Ge, Y., Chen, L., & Sun, F. (2008). Finite-time thermodynamic modelling and analysis of an irreversible Otto-cycle. Applied Energy, 85(7), 618-624.
Chen, L. (2004). Advances in finite time thermodynamics: analysis and optimization. Nova Publishers.
Zhao, J., & Xu, F. (2018). Finite-time thermodynamic modeling and a comparative performance analysis for irreversible Otto, Miller and Atkinson Cycles. Entropy, 20(1), 75.
Wu, C. (1999). Recent advances in finite-time thermodynamics.
Kaushik, S. C., Tyagi, S. K., & Kumar, P. (2017). Finite time thermodynamics of power and refrigeration cycles. Springer International Publishing.
Bejan, A. (2013). Entropy generation minimization: the method of thermodynamic optimization of finite-size systems and finite-time processes. CRC press.
Arabaci, E. (2020). Performance analysis of a novel six-stroke otto cycle engine. Thermal Science, (00), 144-144.
Arabacı, E. (2021). Simulation and performance analysis of a spark ignition engine using gasoline and LPG as fuel. Journal of the Faculty of Engineering and Architecture of Gazi University, 36(1), 447-457.
