Investigation of Stroke/Bore Ratio Effects in Spark Ignition Engines via Exergy Analysis

Yıl 2024, Cilt: 65 Sayı: 714, 121 - 145, 29.04.2024

İsmet Sezer

https://doi.org/10.46399/muhendismakina.1257235

Öz

This study investigates theoretically the effects of stroke/bore (s/b) ratio with availability (exergy) analysis in LPG (100% Propane) fuelled spark ignition (SI) engines. For this purpose, a two–zone quasi–dimensional cycle model of SI engines has been used. The combustion process is simulated as turbulent flame entrainment model, the intake and exhaust processes is simulated by using the simple empirical equations in the cycle model. The principles of the second law of thermodynamics were applied to the cycle model in order to perform the exergy analysis. In the exergy analysis, the exergetic terms such as the exergies transferred by heat, work and exhaust, irreversibilities, fuel chemical exergy, thermomechanical exergy and total exergy were calculated for the selected s/b ratios. In addition, the first and second law efficiencies and indicted specific fuel consumption were also calculated. Thus, the effects of s/b ratio on the exergetic terms, the first and second law efficiencies and indicated specific fuel consumption were determined for LPG fuelled SI engines. The results of the study showed that the increase of the s/b ratio reduces the values of the heat losses, irreversibility and indicated specific fuel consumption, increases the cycle work, exergy losses by exhaust gasses with the first and second law efficiencies in SI engines. The increasing of stroke/bore ratio from 0.7 to 1.3 in LPG fuelled SI engines decreases the heat losses by 10.67%, irreversibilities by 1.89% and indicated specific fuel consumption by 3.91%, while it increases exergy transfer with work by 4.12%, exergy losses with exhaust gasses by 2%, the first law efficiency by 4.07% and the second law efficiency by 4.08%, respectively.

Anahtar Kelimeler

Spark ignition engine, LPG, stroke/bore ratio, exergy analysis, irreversibilities, efficiency

LPG YAKITLI BUJİ ATEŞLEMELİ MOTORLARDA STROK/ÇAP ORANI ETKİLERİNİN EKSERJİ ANALİZİYLE İNCELENMESİ

Öz

Sunulan çalışmada LPG (%100 Propan) yakıtlı buji ateşlemeli motorlarda strok/çap (s/ç) oranının etkileri kullanılabilirlik (ekserji) analiziyle teorik olarak incelenmiştir. Bu amaçla iki bölgeli yanma modeline sahip sanki boyutlu bir buji ateşlemeli çevrim modeli kullanılmıştır. Çevrim modelinde yanma işlemi türbülanslı alev yayılması yaklaşımıyla, emme ve egzoz işlemleri ise basit ampirik bağıntılar kullanılarak modellenmiştir. Ekserji analizini gerçekleştirmek için kullanılan çevrim modeline termodinamiğin ikinci kanunuyla ilgili yaklaşımlar uygulanmıştır. Ekserji analizinde ısı, iş ve egzozla transfer edilen ekserjiler, tersinmezlikler, yakıt kimyasal ekserjisi, termomekanik ekserji ve toplam ekserji gibi ekserjitik terimler seçilen strok/çap oranları için hesaplanmıştır. Ayrıca, 1. ve 2. Kanun verimleri ile indike özgül yakıt tüketimi de hesaplanmıştır. Böylece, buji ateşlemeli LPG yakıtlı motorlarda s/ç oranının ekserjitik terimler, 1. ve 2. Kanun verimleri ve indike özgül yakıt tüketimi üzerindeki etkileri belirlenmiştir. Çalışma sonuçları, LPG yakıtlı buji ateşlemeli motorlarda s/ç oranının artırılmasının ısı kayıpları ve tersinmezlik değerlerini ve indike özgül yakıt tüketimini azalttığını, çevrim işi, egzoz gazlarıyla kaybedilen ekserji, 1. Kanun verimini ve 2. Kanun verimini artırdığını göstermiştir. LPG yakıtlı buji ateşlemeli motorlarda strok/çap oranının 0,7 değerinden 1,3 değerine çıkarılması ısı kayıplarını %10,67, tersinmezlikleri %1,89 ve indike özgül yakıt tüketimini %3,91oranlarında azaltırken işle transfer edilen ekserjiyi %4,12, egzozla kaybedilen ekserjiyi %2, 1. Kanun verimini %4,07 ve 2. Kanun verimini %4,08 oranlarında artırmıştır.

Anahtar Kelimeler

Buji ateşlemeli motor, LPG yakıtı, strok/çap oranı, ekserji analizi, tersinmezlikler, verim

Kaynakça

• Poulos, S. G., & Heywood, J. B. 1983. “The effect of chamber shape on spark ignition engine combustion,” Society of Automotive Engineering, SAE paper no. 830334, p. 1-24. DOI: https://doi.org/10.4271/830334
• Sung, N. W., & Jun S. P. 1997. “The effects of combustion chamber geometry in an SI engine,” Society of Automotive Engineering, SAE paper no. 972996, p. 227-239. DOI: https://doi.org/10.4271/972996
• Filipi, Z. S., & Assanis, D. N. 2000. “The effect of the stroke-to-bore ratio on combustion, heat transfer and efficiency of a homogeneous charge spark ignition engine of given displacement,” International Journal of Engine Research, vol. 1(2), p. 191-208. DOI: https://doi.org/10.1243/1468087001545137
• Sher, E., & Bar-Kohany, T. 2002. “Optimization of variable valve timing for maximizing performance of an unthrottled SI engine-a theoretical study,” Energy, vol. 27, p. 757-775. DOI: https://doi.org/10.1016/S0360-5442(02)00022-1
• Hu, Z., Whitelaw, J. H., & Vafidis, C. 1992. “Flame propagation studies in a four-valve pentroof-chamber spark ignition engine,” Society of Automotive Engineering, SAE paper no. 922321, p. 1-11. DOI: https://doi.org/10.4271/922321
• Caton, J. A. (2002). Detailed results for nitric oxide emissions as determined from a multiple-zone cycle simulation for a spark-ignition engine. Fall Technical Conference of the ASME, Internal Combustion Engine Division, p. 1-19, New Orleans, Los Angeles.
• Rakopoulos, C. D., & Giakoumis, E. G. 2006. “Second law analyses applied to internal combustion engines operation,” Progress in Energy and Combustion Science, vol. 32(1), p. 2-47. DOI: https://doi.org/10.1016/j.pecs.2005.10.001
• Moran, M. J, & Shapiro H. N. (2000). Fundamentals of engineering thermodynamic. New York, USA, John Wiley & Sons Inc.
• Caton, J. A. (2000). A review of investigations using the second law of thermodynamics to study internal-combustion engines. SAE World Congress, p. 1-15, Detroit, Michigan.
• Rakopoulos, C. D. 1993. “Evaluation of a spark ignition engine cycle using first and second law analysis techniques,” Energy Conversion and Management, vol. 34(12), p. 1299-1314. DOI: https://doi.org/10.1016/0196–8904(93)90126-U
• Gallo, W. L. R., & Milanez, L. F. 1992. “Exergetic analysis of ethanol and gasoline fueled engines,” Society of Automotive Engineers, SAE paper no. 920809, p. 907-915. DOI: https://doi.org/10.4271/920809
• Shapiro H. N., & Van Gerpen, J. H. 1989. “Two zone combustion models for second law analysis of internal combustion engines,” Society of Automotive Engineers, SAE paper no. 890823, p. 1408-1422. DOI: https://doi.org/10.4271/890823
• Alasfour, F. N. (1997). “Butanol-a single-cylinder engine study: availability analysis,” Applied Thermal Engineering, vol. 17(6), p. 537-549. DOI: https://doi.org/10.1016/S1359-4311(96)00069-5
• Caton, J. A. (1999). Results from the second-law of thermodynamics for a spark-ignition engine using a cycle simulation. Fall Technical Conference of the ASME, Internal Combustion Engine Division, p. 35-49, Ann Arbor, Michigan.
• Caton, J. A. (2000). Operation characteristics of a spark-ignition engine using the second law of thermodynamics: effects of speed and load. SAE World Congress, p. 1-17, Detroit, Michigan.
• Ferguson, C. R. (1985). Internal combustion engine, applied thermosciences. New York, USA, John Wiley & Sons Inc.
• Ferguson C. R., Green R. M., & Lucht, R. P. 1987. “Unburned gas temperatures in internal combustion engine II: Heat release computations,” Combustion Science and Technology, vol. 55, p. 63-81. DOI: https://doi.org/10.1080/00102208708947071
• Blizard, N. C., & Keck, J. C. 1974. “Experimental and theoretical investigation of turbulent burning model for internal combustion engines,” Society of Automotive Engineering, SAE paper no 740191, p. 846-864. DOI: https://doi.org/10.4271/740191
• Gülder, Ö. (1984). “Correlations of laminar combustion data for alternative S.I. engine fuels,” Society of Automotive Engineers; SAE paper no. 841000, p. 1-23. DOI: https://doi.org/10.4271/841000
• Sezer, I., & Bilgin, A. 2008. “Mathematical analysis of spark ignition engine operation via the combination of the first and second laws of thermodynamics,” Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, vol. 464, p. 3107-3128. DOI: https://doi.org/10.1098/rspa.2008.0190
• Sezer, I., & Bilgin, A. 2012. “Exergetic evaluation of speed and load effects in spark ignition engines,” Oil & Gas Science and Technology, vol. 67(4), p. 647-660. DOI: https://doi.org/10.2516/ogst/2012002
• Cengel, Y. A., & Boles, M. A. (1994). Thermodynamics, an engineering approach. 2nd Edition, New York, USA, McGraw-Hill Inc.
• Van Gerpen, J. H., & Shapiro, H. N. 1990 “Second law analysis of diesel engine combustion,” Transaction of ASME Journal of Engineering for Gas Turbines and Power, vol. 112, p. 129-137. DOI: https://doi.org/10.1115/1.2906467
• Caton, J. A. (1999). Results from the second-law of thermodynamics for a spark-ignition engine using a cycle simulation. Proceedings of the ASME-ICED Fall Technical Conference, p. 35-49, Ann Arbor: Michigan.
• Caton, J. A. (2000). Operation characteristics of a spark-ignition engine using the second law of thermodynamics: effects of speed and load. SAE World Congress, p. 1-17, Detroit: Michigan.
• Kotas, T. J. (1995). The exergy method of thermal plant analysis. Florida, USA, Krieger Publishing.
• Fanhua, M., Chuanli, L., Deming, J., & Longbao, Z. 1994. “Study on validation of turbulent entrainment combustion model for spark-ignition engines,” Society of Automotive Engineers, SAE paper no 941935, p. 1-15. DOI: https://doi.org/10.4271/941935
• Yamin, J. A. A., Gupta, H. N. & Bansal, B. B. “The effect of combustion duration on the performance and emission characteristics of propane-fueled 4-stroke S. I. engines,” Emirates Journal for Engineering Research, vol. 8, no. 1, 2003, p. 1-14.