Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2019Theoretical investigation on combustion characteristics of ethanol-fueled dual-plug SI engine
Altın, İsmail; Bilgin, Atilla; Sezer, İsmet
In this study, effects of equivalence ratio, spark timing and spark plug number and locations on combustion characteristics were theoretically investigated using an ethanol-fueled dual-plug SI engine. Two-zone quasi-dimensional model was used throughout analyses. Three spark plug configurations (diagonally, centrally and side located), three equivalence ratios (0.8, 0.9, and 1.0), and three spark timings (−30, −25, and −20 CA @ BTDC) were considered to analyze variation of total burn duration, mass fraction burned, cylinder pressure, and temperatures (exhaust and maximum burned gas). Variation of mass fraction burned and cylinder pressure were also investigated at lean mixture ratio and 2800 rpm (MBT engine speed). Lastly, the effect of engine speed on total burn duration, maximum cylinder pressure and aforementioned temperatures were investigated in the range of 1000–6000 rpm. The findings show that dual-plug configuration yields approximate combustion characteristics by comparison with centrally located single plug configuration in ethanol-fueled SI engine.
- MakaleYalnız künye2014Exergetic analysis of using the gaseous fuels in spark ignition engines
Sezer, Ismet; Bilgin, Atilla
This paper aims to investigate the use of alternative gaseous fuels in spark ignition engines via an exergy analysis. A quasi-dimensional two-zone thermodynamic cycle model is used for this purpose. The intake and exhaust processes are computed by a simple approximation method, and the processes (that is, compression, combustion, and expansion) are simulated in detail. The turbulent flame propagation process is used for the combustion simulation. The second law of thermodynamics is applied to the cycle model to perform the exergy analysis. The exergy transfers associated with heat, work, and exhaust; the irreversibilities, thermomechanical exergy, fuel chemical exergy, and total exergy have been computed in the exergy analysis. A distribution of the fuel exergy, the energy-based (the first law) efficiency, and the exergetic (the second law) efficiency were also calculated during the exergy analysis. Thus, the effects of using natural gas and liquefied petroleum gas on the exergetic terms and the efficiencies are investigated. The results of the study show that investigated alternative gaseous fuels have affected the variations in the exergy transfers, irreversibilities, and efficiencies. The gaseous fuels are suitable from the exergy point of view because of the lessened exergy destruction rate, but they suffer from the engine performance reduction.
- MakaleYalnız künye2013COMPARATIVE INVESTIGATION THE USE OF METHANOL AND METHYL TERTIARY BUTYL ETHER IN GASOLINE ON ENGINE PERFORMANCE, CO EMISSIONS AND FUEL COST
Sezer, Ismet; Bilgin, Atilla
This study is concerned with investigating experimentally the effects of methanol and Methyl tert-Butyl Ether (MTBE) blending to base gasoline on the performance CO emissions and fuel cost of a spark ignition (SI) engine. The fuel blends were prepared by addition 5, 10, 15, and 20 vol % of methanol and MTBE with a specified amount of base gasoline. The methanol- and MTBE-gasoline blends were designated as M5, M10, M15, M20, and MTBE5, MTBE10, MTBE15, MTBE20, respectively. Experiments were conducted under various engine speeds, spark timings (STs), and compression ratios (CRs). The engine was operated under wide-open throttle conditions. The results of the study showed that the M5 and MTBE10 blends yield the best engine performance in terms of the brake mean effective pressure (bmep), while the M20 and MTBE15 blends are the best performers in terms of brake thermal efficiency (bte). Moreover, M20 and MTBE10 blends give the minimum CO emission values. The economical analysis performed in the study is based on both the current blending fuel prices in Turkey and brake specific fuel consumption (bsfc) of the engine while using gasoline, methanol-gasoline, and MTBE-gasoline blends. It was obtained that, in contrast to the improvement of engine performance, efficiency and CO emissions, methanol and MTBE blends caused increases in fuel costs because of the expensive methanol and MTBE prices in Turkey. Uncertainty analysis was also performed in this study, and it was found that; the uncertainties in the measurement devices do not have noticeable influences on the variations of engine characteristics.
- MakaleYalnız künye2013Effects of charge properties on exergy balance in spark ignition engines
Sezer, Ismet; Bilgin, Atilla
This study investigates the effects of the air-fuel mixture (charge) properties on the exergy balance in spark ignition engines. A thermodynamic cycle model including compression, combustion and expansion processes is used. The principles of the second law are applied to the cycle model to perform an exergy analysis. Variation of the exergetic variables during the investigated portion of the cycle are examined as a function of the charge properties, i.e., fuel-air equivalence ratio, residual gas fraction and initial charge temperature. The results show that increasing fuel-air equivalence ratio causes an increase in irreversibilities and also exergy losses with heat transfer and exhaust gases, but enriching the air-fuel mixture beyond the stoichiometric ratio makes no significant contribution to the exergy transfer with work transfer. A slightly lean mixture also gives the best first and second law efficiencies. It is observed that there is a linear relation between the residual gas fraction and the exergetic variables. An increase in the residual gas fraction decreases the irreversibilities and exergy losses aside from the exergy transfer with work transfer. However, increasing the residual gas fraction positively affects the first and second law efficiencies because of the diluting of the charge. Increase of initial charge temperature creates a reduction in the irreversibilities and the exergy losses and, it also results in a lower exergy output by work transfer. Further, increase of initial charge temperature negatively influences the first and second law efficiencies.