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- MakaleAçık Erişim2012Exergetic evaluation of speed and load effects in spark ignition engines; [Évaluation exergétique des effets de la vitesse et de la charge dans les moteurs à allumage par étincelle]
Sezer, I.; Bilgin, A.
This study investigates the effects of various operating conditions in spark ignition engines via an exergy analysis. A thermodynamic cycle model including compression, combustion and expansion processes was used for investigation. Induction and exhaust processes were computed with a simple approximation method. The principles of the second law were applied to the cycle model to perform the exergy analysis. Exergetic variables, i.e., the exergy transfers with heat and work, irreversibilities, thermomechanical exergy, fuel chemical exergy and total exergy were calculated in the exergy analysis. Variation of the exergetic parameters and the distribution of them into the fuel exergy were determined for various operating conditions, i.e., engine speed and load. The first and second law efficiencies and specific fuel consumption were also computed to reveal the optimum operating conditions. The results show that the exergy transfer with heat decreases and the exergy transfer with exhaust gases increases with increasing engine speed. Engine speed of 3 000 rpm gives the maximum exergy transfer as work, the minimum irreversibility and the best efficiency and fuel consumption. Exergy transfers with heat, work and exhaust and irreversibilities increase with increasing engine load. Additionally, the first and second law efficiencies increase and fuel consumption decreases with increasing engine load, so a high engine load gives the best efficiency and fuel consumption.
AtıfScopus7WoS7OpenAlex9İncele - MakaleYalnız künye2011Scopus SJRQ1Alternative gaseous fuels in port fuel injection spark ignition engines
Sezer, I.
This paper investigates the use of alternative gaseous fuels in port fuel injection spark ignition engines via the Lotus engine simulation program. To this end, the engine model for a port fuel injection spark ignition engine was designed, and engine performance was determined separately for gasoline and alternative gaseous fuels, i.e. compressed natural gas and liquefied petroleum gas. According to the results, brake thermal efficiency increases while engine performance and fuel consumption decrease with methane and propane when compared to gasoline under the same conditions. While a slight increase in the fuel/air equivalence ratio of gaseous fuels improves the engine performance, fuel consumption remains almost stable. Another factor that enhances engine performance is the increasing compression ratio for methane and propane. In this manner, performance values that are closer/equal to gasoline are achieved. Under these conditions, fuel consumption decreases notably, while significant increases are observed in brake thermal efficiency.
AtıfScopus4WoS4OpenAlex3İncele