Ahmet Necati Özsezen

This study investigates the influence of ignition timing and high-volume alcohol gasoline blends on the performance, combustion, knock, and emission characteristics of a direct-injection spark-ignition (DISI) engine. Experiments were conducted at 5000 rpm under full-load and slightly rich conditions (λ ≈ 0.91) using neat gasoline and alcohol–gasoline blends containing 30% alcohol and 70% gasoline by volume, including ethanol–gasoline, iso-butanol–gasoline, and ethanol–iso-butanol–gasoline blends, at three ignition-timing settings. Results indicate that maximum work output and the highest mechanical efficiency (82.6%) were achieved by the E15ISB15 ternary blend at advanced ignition timings, whereas it reached its peak brake thermal efficiency (30.2%) under the baseline (MAIN) timing condition. Although oxygenated blends increased brake specific fuel consumption, E30 yielded the highest indicated mean effective pressure. Combustion analysis revealed that advancing spark timing increased the maximum in-cylinder pressure and shifted its occurrence closer to top dead center. Moreover, binary blends (E30, ISB30) exhibited higher in-cylinder pressure values and more advanced combustion phasing than baseline gasoline (G100), while maintaining high combustion stability (CoV _IMEP < 1.1%). Retarding ignition effectively suppressed knocks, stabilizing maximum amplitude of pressure oscillations below 1.0 bar. Conversely, under knock-prone advanced timing, E15ISB15 demonstrated superior auto-ignition resistance over G100 and E30. Environmentally, high-alcohol blends reduced soot formation by over 90%, with E15ISB15 achieving a 97.5% reduction at baseline timing. Their oxygenated structure enhanced carbon oxidation, lowering CO and THC emissions, while E30 exhibited the lowest CO ₂ and NO emissions. Overall, coupling the E15ISB15 blend with optimized ignition timing offers an effective strategy for maximizing DISI engine efficiency while mitigating knock and emissions.

This study presents the systematic design, multi-surface integration, and experimental validation of a Vehicle-Integrated Photovoltaic (VIPV) system tailored for an electric urban delivery motorcycle. To maximize power density within highly constrained vehicular surface areas, a high-density shingled cell architecture was developed to elevate string voltage and optimize conversion efficiency. Ethylene Tetrafluoroethylene (ETFE) was used as a lightweight front-sheet material, providing more stable efficiency yields compared to standard Polyethylene Terephthalate (PET)-coated alternatives under fluctuating environmental conditions. To mitigate severe mismatch losses caused by the multi-oriented geometry of the courier delivery box, a multi-channel Maximum Power Point Tracking (MPPT) architecture was commissioned to independently manage heterogeneous irradiance profiles. Real-world outdoor testing conducted in Ankara, Türkiye, over a cumulative active test duration of 40,980 seconds (~11.4 hours), demonstrated a cumulative energy harvest of 364.9 Wh. This solar gain successfully yielded a 20.3% increase in the battery State-of-Charge (SoC) and provided an additional grid-independent driving range of approximately 14.2 km. Despite efficiency fluctuations induced by dynamic urban shading, the integration of flexible shingled PV panels with a tailored power electronics topology represents a promising approach to enhance the sustainability and range autonomy of lightweight electric mobility.

To encourage the use of alternative fuels while limiting the use of fossil fuels, researchers have focused on using more environmentally friendly fuels. Furthermore, the goal is to improve engine performance to increase energy efficiency. A four-stroke, single-cylinder, diesel engine with a common rail fuel injection system runs with diesel, biodiesel, and biodiesel–alcohol fuel blends. The tests were performed using a constant engine speed of 2000 rpm and three different gas pedal positions (20%, 50% and 80%). It was found that maximum cylinder gas pressure increased in all test fuels with increased gas pedal position (GPP) and advanced injection start time. In general, the maximum heat release rate increased in blended fuels compared to diesel fuel. In addition, it was seen that advanced injection timings caused an increase in ignition delay in all fuel types. In the same test conditions, it was observed that biodiesel–alcohol fuel blends caused an increase in ignition delay by more than 10% compared to diesel fuel (D100), while shortening combustion duration (CD) by more than 10%. A decreasing trend in CO and HC emissions was observed in the use of biodiesel fuel compared to diesel fuel. With the use of biodiesel–alcohol fuel blends, CO₂ emissions tend to decrease. Advanced injection timings caused high NO emissions.

Today, there is a desire to use low‐carbon fuels and non‐petroleum fuels in internal combustion engines. It is also important for energy diversity and security that countries use alternative fuels produced from local energy resources in energy production by blending them with fossil fuels. The purpose of this study is to investigate the effect of ignition timing on combustion parameters and knocking tendency by varying the initial flame kernel by varying the ignition timing ±5 ^o CA while using gasoline blends containing 30% alcohol by volume, which is a critical blend ratio for a spark ignition (SI) direct injection engine, and to analyze the data obtained. Based on the analysis, it was determined that retarding the ignition timing results in a drop in the cylinder gas pressure curve and a loss of engine power, as combustion takes place in a rapidly expanding cylinder volume. Ignition timing was found to have a direct effect on the magnitude and position of the cylinder gas pressure. Advancing the ignition timing increases the cylinder gas pressure for all fuels, while retarding the ignition timing reduces the cylinder gas pressure and moves it away from the top dead center. The knocking tendency of the engine is reduced when critical alcohol/gasoline blends are used. Significant reductions in NO _x and PM emissions have been achieved when using alcohol blends.

This study investigated the combustion, sound and vibration characteristics of petroleum-based diesel fuel (PBDF) and waste cooking oil methyl ester (WCOME) at different rail pressures and engine loads. In the engine tests, engine vibration levels varied significantly with fuel type, rail pressure and engine load, with PBDF producing higher vibration levels at lower rail pressures and WCOME tending to produce lower vibration levels at higher rail pressures. In the 4–5 kHz frequency band defined as the premixed combustion phase, the cylinder sound pressure level was 99.4 dB for WCOME and 105.2 dB for PBDF at 950 bar. The increase in rail pressure results in an increase in engine vibration, so the lowest vibration amplitude is at 40 Nm and 750 bar, while the lowest total engine noise is 86 dBA for WCOME and 90.6 dBA for PBDF. An increase in THC and CO emissions was observed with the use of WCOME compared to PBDF, while CO ₂ and NO _x emissions decreased. It was observed that as the rail pressure increased, CO ₂ and NO _x emissions increased approximately twofold, but CO and THC emissions decreased approximately 25% and 45% respectively. Analysis of variation (ANOVA) and regression analysis were used to analyze the effect of engine input parameters on output parameters. The influence of the factors on the response is confirmed by larger F-values and is considered statistically significant at 95% confidence level when p < 0.05. It is statistically observed that engine load and rail pressures have a significant effect on the engine response parameters of THC, CO, CO ₂ , NO _x and noise.