Browsing by Author "Kokkulunk, Gorkem"

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Gradient Boosting Machine for Performance and Emission Investigation of Diesel Engine Fueled With Pyrolytic Oil-Biodiesel and 2-Ehn Additive
(Royal Soc Chemistry, 2023) Okumus, Fatih; Sonmez, Halil Ibrahim; Safa, Aykut; Kaya, Cenk; Kokkulunk, Gorkem
In this study, the effect of the addition of 2-EHN (2-ethylhexyl nitrate) into binary blends of biodiesel-waste tire pyrolysis oil (WTPO) on the performance and emissions of a CI engine has been investigated. Experiments have been conducted within a pre-defined domain of fuel ratios, and load-speed data. A GBM (gradient boosting machine) algorithm has successfully predicted fuel consumption and emissions of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC), with regard to R squared error (R-2), root-mean-square error (RMSE), and mean absolute error (MAE) values as performance indicators. Extrapolation was carried out to predict the effect of fuel ratios and engine speeds. It was found that the addition of 2-EHN into the pyrolytic oil-biodiesel blends may reduce BSFC and CO, but it increases CO2, NOx and HC. The maximum reductions with 2-EHN addition are recorded as 3% for BSFC and 34% for CO, and the maximum increases are observed to be 10% for CO2, 9% for NOx and 28% for HC. Using 2-EHN as an additive to binary pyrolytic-biodiesel fuel in a CI engine, the most effective variables are found to be load for CO2 and CO, speed for NOx, and binary fuels for HC.
Performance Investigation and Emission Analysis of a Diesel Engine Operated on Hydrogen and Ammonia
(Pergamon-Elsevier Science Ltd, 2025) Kanberoglu, Berna; Okumus, Fatih; Sonmez, Halil Ibrahim; Gonca, Guven; Kokkulunk, Gorkem; Kaya, Cenk; Aydin, Zafer
This study investigates binary-fuel operation of a single-cylinder diesel engine using hydrogen and ammonia as secondary fuels through comprehensive CFD simulations. The effects of injector hole diameter, injection timing, and injection duration on combustion, performance, and emissions were systematically analyzed under both full-and partial-load conditions. Parametric analyses further revealed that variations in nozzle diameter and injection duration exerted a stronger influence on indicated power and efficiency than intake air conditions. The results indicate that injector geometry strongly influences combustion dynamics. At full load, indicated power averaged 6.0 kW, with the highest value of 6.5 kW obtained in ammonia-diesel operation at the smallest nozzle diameter. At partial load, hydrogen demonstrated superior stability, achieving the highest thermal efficiency of 43.17 % in the L50D100 configuration. A 0.05 mm increase in injector hole diameter reduced NO emissions in hydrogen-diesel operation by 24.7 %, highlighting the sensitivity of NO formation to injector design. Fuel type largely dictated emission characteristics. Hydrogen consistently produced very low CO2 emissions (approximately 459 g/kWh) owing to its carbon-free nature, though it tended to elevate NO levels due to high combustion temperatures. Ammonia, by contrast, provided lower NO and CO2 emissions under partial load but showed reduced indicated power and efficiency compared to hydrogen. Intake air conditions also played a significant role: increasing intake pressure by 0.2 bar lowered CO2 emissions by up to 27 g/kWh in the L50D100 configuration. Overall, the study demonstrates that binary-fuel diesel operation with hydrogen and ammonia is highly sensitive to engine operating parameters.
Waste To Energy Conversion: Pyrolytic Oil and Biodiesel as a Renewable Fuel Blends on Diesel Engine Combustion, Performance, and Emissions
(Taylor & Francis inc, 2022) Sonmez, Halil Ibrahim; Okumus, Fatih; Kaya, Cenk; Aydin, Zafer; Safa, Aykut; Kokkulunk, Gorkem
The use of pyrolytic oil (WTPO) obtained from waste vehicle tires in Turkey is evaluated and encouraged within the scope of YEKDEM (Turkey Renewable Energy Resources Support Mechanism). In order to benefit from this incentive, WTPO must be used as the main fuel in diesel engines. For this reason, in this study, unlike all other studies in the literature, the use of WTPO at a high rate was examined. The effects of biodiesel and WTPO mixtures containing high WTPO on engine performance and emissions were investigated. The experiments were carried out at 2800 rpm engine speed, where the maximum power was obtained, and at 4 different loads as 100%, 75%, 50%, and 25%. When the obtained results are examined. The lowest brake thermal efficiency (BTE) value was obtained in P100 fuel at 25% load and its value was 16.21%. Brake specific fuel consumption (BSFC) data were similar for all test fuels under the same load conditions. Based on the heat release rate and in-cylinder pressure data, it was noted that biodiesel reduced the ignition delay time. The maximum in-cylinder temperature was 1723.4 K and the maximum exhaust temperature was 590 degrees C with the use of P60B40 fuel. The lowest nitrogen oxides (NOx) value results were obtained at 100% load. Hydrocarbon (HC) emissions decreased from 1.13 g/kWh to 0.13 g/kWh for P100 fuel as load increased form 25% to 100%. All these results show that although the biodiesel additive slightly worsened the emissions, positive results were obtained for the performance data.
Renewable Energy Resources: Combustion and Environmental Impact of Diesel With Pyrolytic and Biodiesel Blends
(Sage Publications Ltd, 2023) Sonmez, Halil Ibrahim; Okumus, Fatih; Safa, Aykut; Aydin, Zafer; Kaya, Cenk; Kokkulunk, Gorkem
The worldwide increasing energy demand, interest in alternative energy production and limited resources have made it inevitable to turn to recovering wastes, such as waste tires. Waste tires with annual increase of 2%, corresponding to significant reserves all over the world, brings a serious environmental pollution. In this study, energy recovery was planned considering environmental pollution caused by waste tires and waste cooking oils, both. Accordingly, performance and emission analyzes were carried out using fuels formed by mixing pyrolytic oil obtained from waste tires (WTPO) and biodiesel obtained from waste cooking oil with diesel fuel in a single cylinder engine. The experiments are carried out at 2800 rpm and at full load condition. The findings of engine performance and exhaust emissions were evaluated. While the maximum brake specific fuel consumption (Bsfc) value was determined as 2100 g/kWh for blend fuel of 30% biodiesel and 10% WTPO in diesel fuel, the maximum brake thermal efficiency (Bte) value was determined as 33.541% for P30 fuel. The crank angles yielding maximum in-cylinder pressures approach to top dead center, with increasing biodiesel fraction while keeping WTPO fraction constant. While the increase in the amount of WTPO in the test fuels has an effect on the increase of CO emissions, and increasing biodiesel ratio has reduced the CO emissions. Also the use of biodiesel without WTPO increases NOx emissions slightly, while providing an effective reduction at high WTPO fractions. At low WTPO fractions, biodiesel has reduced HC emissions, while at high WTPO fractions has increased.