Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 15Citation - Scopus: 15Predicting the Effects of Direct-Injected Fuels Co-Powered by High-CO2 Biogas on RCCI Engine Emissions Using Kinetic Mechanisms and Multi-Objective Optimization(Elsevier, 2024-04) Dalha, Ibrahim B.; Koca, Kemal; Said, Mior A.; Rafindadi, Aminu D.High inert gas content in biogas resulted in poor burning and emissions attributes, though scarcely investigated in reactivity controlled compression ignition (RCCI). Established kinetic mechanisms were combined with multiobjective optimization to investigate, predict, and analyze emissions occurrence and trade-offs for reduced environmental impacts. The work examined the impact of direct-injected high reactivity fuels (HRF) and portinjected Biogas at various inert gas (carbon dioxide, CO2) rates (25 - 45% vol), biogas fractions (40 - 70%), speeds (1600 - 2000 rpm), and loads (4.5 - 6.5 bar IMEP) on emissions of RCCI engine, experimentally. The findings revealed that while engine speeds greatly decreased CO (carbon monoxide) and NOx (nitrate oxide) emissions with rising unburned hydrocarbon (UHC) regardless of HRF employed, higher engine load significantly reduced UHC emissions. Diesel-biogas reduces NOx emissions and performs better in reducing CO and UHC emissions at lower speeds than B5-biogas, except in low-level loads. Although increasing CO2 impact led to a reduction in UHC and CO emissions, the biogas proportion was the most significant variable. The main factor influencing increased NOx emissions was engine load, which is inversely correlated with reduced NOx and increased particulate emissions owing to high CO2 content and biogas proportion. The premixed mode's optimisation outcome confirms the trade -off reduction at 5.5 bar IMEP, 35.586% CO2, and 50% fraction. As a result, running the RCCI engine with direct-injected diesel co-powered in equal proportion with high-CO2 biogas cuts the emissions trade -off dramatically, limiting the environmental repercussions of the emissions.Article Citation - WoS: 46Citation - Scopus: 46Nuclear Energy Consumption, Energy Access and Energy Poverty: Policy Implications for the COP27 and Environmental Sustainability(Elsevier Sci Ltd, 2023-11) Bashir, Muhammad Farhan; Ma, Beiling; Sharif, Arshian; Ao, Tong; Koca, KemalThe ever-increasing energy resource demand and subsequent environmental challenges mean that policymakers have shifted their focus to nuclear energy to address energy and environmental issues due to its unlimited potential. The current study investigates the role of nuclear energy consumption to unveil contextual information and report novel evidence concerning the significance of energy and environmental policies. This research is a novel attempt to outline methodological and topical contributions, thematic analysis, co-citation analysis, and country-collaboration analysis. As energy and environmental solutions have been prioritized within sustainable development goals, our research approach would allow policymakers and researchers to understand the extent to which nuclear energy can provide solutions towards environmental sustainability and identify research limitations to overcome by future studies. Moreover, our extensive analysis allows us to argue that nuclear energy impacts energy demand and is the most critical factor in fulfilling environmental commitments under regional and international environmental agreements.Article Citation - WoS: 19Citation - Scopus: 21Investigation of the Effect of Hidden Vortex Generator-Flap Integrated Mechanism Revealed in Low Velocities on Wind Turbine Blade Flow(Pergamon-Elsevier Science Ltd, 2023-07) Ozden, Mustafa; Genc, Mustafa Serdar; Koca, KemalIn this study, the flap and vortex generator (VG) mechanisms which were employed separately in aircraft were used as integrated first in literature. In this mechanism, the flap motion triggered and activated the VGs when it was needed at low speeds. Thus, this flap mechanism eliminated the unnecessary drag force generation when VGs were not needed. Numerical simulations which were validated with experimental data were employed in the study. In the first step, the flow characteristics formed on the S809 airfoil with 4 different flap angles ( beta = 30 degrees, 20 degrees, 10 degrees, 0 degrees) were investigated without the VG. Then, those flow structures formed on the S809 airfoil with both flap and VG were examined under the same conditions. According to the results, utilizing flap and VGs together had a positive impact at low wind speeds. Moreover, due to the flap and vortex generator integrated mechanism closed up to be not unnecessary drag formation at high wind speeds, thus those structures increased further to the positive effect with the increasing wind velocity. In terms of energy output, it was shown that this novel idea provided more energy output in this study.Article Citation - WoS: 11Citation - Scopus: 13Investigating the Best Automatic Programming Method in Predicting the Aerodynamic Characteristics of Wind Turbine Blade(Pergamon-Elsevier Science Ltd, 2023-08) Arslan, Sibel; Koca, KemalAutomatic programming (AP) is a subfield of artificial intelligence (AI) that can automatically generate computer programs and solve complex engineering problems. This paper presents the accuracy of four different AP methods in predicting the aerodynamic coefficients and power efficiency of the AH 93-W-145 wind turbine blade at different Reynolds numbers and angles of attack. For the first time in the literature, Genetic Programming (GP) and Artificial Bee Colony Programming (ABCP) methods are used for such predictions. In addition, Airfoil Tools and JavaFoil are utilized for airfoil selection and dataset generation. The Reynolds number and angle of attack of the wind turbine airfoil are input parameters, while the coefficients CL, CD and power efficiency are output parameters. The results show that while all four methods tested in the study accurately predict the aerodynamic coefficients, Multi Gene GP (MGGP) method achieves the highest accuracy for R2Train and R2Test (R2 values in CD Train: 0.997-Test: 0.994, in CL Train: 0.991-Test: 0.990, in PE Train: 0.990-Test: 0.970). By providing the most precise model for properly predicting the aerodynamic performance of higher cambered wind turbine airfoils, this innovative and comprehensive study will close a research gap. This will make a significant contribution to the field of AI and aerodynamics research without experimental cost, labor, and additional time.Article Citation - WoS: 22Citation - Scopus: 23Experimental Flow Control Investigation Over Suction Surface of Turbine Blade With Local Surface Passive Oscillation(Pergamon-Elsevier Science Ltd, 2022-12) Koca, Kemal; Genc, Mustafa Serdar; Veerasamy, Dhamotharan; Ozden, MustafaImpact of the local flexible membrane (LFM) on aerodynamic phenomena including the formation of a laminar separation bubble (LSB) and transition to turbulence was experimentally investigated over the suction surface of a Clark-Y airfoil first time in literature. The experiments such as aerodynamic force measurement, smoke-wire flow visualization and hot-film tests were carried out at the free-stream velocity of U infinity = 3.2 m/s, U infinity = 6.4 m/s, U infinity = 9.6 m/s, U infinity = 12.8 m/s, and Reynolds number based upon on the chord length was Rec = 3.5 x 104, Rec = 7.0 x 104, Rec = 1.05 x 105 and Rec = 1.4 x 105, respectively. The experimental angle of attack was set at 0 degrees = alpha <= 20 degrees. In detailed intermittency analysis by the hot-film sensor over the uncontrolled airfoil, it was seen that the LSB and transition to turbulence formed close to the trailing edge at a lower angle of attack, and it moved towards the leading edge when increasing the angle of attack simultaneously. Employing LFM on the suction surface obviously affected the progress of these flow phenomena. In the results of smoke-wire flow visualization, either the size of the laminar separation bubble (LSB) was reduced or its presence was suppressed at lower in-cidences. The aerodynamic force measurement results also supported those behaviors. In particular, at lower incidences, the negative effects of LSB were mitigated, resulting in the presence of a more stable lift curve. Additionally, it was clearly observed that utilizing LFM ensured positive effects, especially at the pre-and the post-stall regions in terms of fewer fluctuations at the CL curve, meaning that less aerodynamic vibration and noise on wind/hydro turbine could be obtained.Article Citation - WoS: 14Citation - Scopus: 15Design Analysis of a Wave Energy Converter for Hydrogen Generation Near Shoreline of Black Sea(Elsevier, 2024-06) Bekci, Eyuep; Koca, Kemal; Bashir, Muhammad FarhanThe generation of electricity from waves has attracted a lot of attention from researchers lately. Despite the vastness and accessibility of wave energy across the majority of the planet, there is a dearth of literature on the production of electricity and hydrogen from wave power. In this paper, a comprehensive simulation related to hydrogen production with an oscillating wave surge converter (OWSC) system was employed for the Black Sea region. The simulations were performed by means of Homer-Pro software and the data were provided thanks to European Marine Observation and Data Network (EMODnet) as well as a novel web-based tool with regards to wave resources. Initial results of web-based tool showed that the hydrogen generation was directly impacted by considerable wave height and wave energy period. As a result, it may change based on the days and months. May had the lowest monthly energy production (3 MWh), while December had the highest monthly energy production (27 MWh). Moreover, the electrolyzers with different efficiencies were investigated with Homer-Pro. The electrolyzer with an efficiency of 85% at 100 kW produced 3301 kg annually, whereas the electrolyzers with 90% and 95% efficiency at 100 kW produced 3419 kg annually and 3422 kg annually, respectively. Apart from those findings, when more efficient electrolyzers were employed in the system, both the capital and replacement costs dropped at the same time.Article Citation - WoS: 9Citation - Scopus: 10Compensating Energy Demand of Public Transport and Yielding Green Hydrogen With Floating Photovoltaic Power Plant(Elsevier, 2024-06) Koca, KemalThe last three decades have seen a dramatic increase in the renewable energy sector as a result of increased human energy consumption and environmental concerns about fossil fuels. Offshore renewable energy sources are the most alluring and promising technologies because of more energy potential, less space, and visual restrictions than onshore ones. Among those, floating solar photovoltaic (FPV) has a remarkable reputation. The present study focuses on a viable way to replace energy resources derived from fossil fuels with renewable solar energy. In this regard, electrical energy demand is investigated where a floating photovoltaic system and integrated hydrogen production unit are employed on water surface of Yamula Dam. Energy demand of public trams would be compensated with electricity generated by FPV and rest of energy would be utilized for hydrogen production. Key results illustrated that in various scenarios, the energy generation amounts were around 31x10 6 kW, 32x10 6 kW, and 39x10 6 kW, while the energy consumption amounts were approximately 24x10 6 kW. It was evident that the energy created more than offset the amount consumed. It was also note that the total costs of entire system were $94.1 M, $78.5 M and $71.2 M according to the different cases. It was also observed that in October and November, the remaining energy from the Bozankaya tram produced the most hydrogen with 125 kg, whereas in September and October, the remaining energy from the Sirio tram produced approximately 70 kg.Article Citation - WoS: 12Citation - Scopus: 12Biogas Intake Pressure and Port Air Swirl Optimization to Enhance the Diesel RCCI Engine Characteristics for Low Environmental Emissions(Elsevier, 2024) Dalha, Ibrahim B.; Koca, Kemal; Said, Mior A.; Rafindadi, Aminu D.Exhaust emission and combustion control in RCCI (reactivity-controlled compression ignition) focused mainly on the direct-injected fuel parameters, urging to investigate the advantages of port-fuel intake parameters. The engine was modified for port injection of Biogas at the valve and RCCI mode. The influence of port swirl ratio (PSR, 0 - 80%) and biogas injection pressure (BIP, 1 - 4 bar) on the diesel RCCI combustion and emissions was tested and optimized at varied loads and 1600 rpm in a port injection at the valve (PIVE) approach. Established kinetic mechanisms were combined with multi-objective optimization to further investigate, predict, and analyze emissions occurrence and trade-offs for reduced environmental impacts. The results show that the radiation absorption triggered by increased CO2 lowers combustion temperature, resulting in prolonged ignition. Setting the airflow to swirl lowers the in-cylinder pressure at elevated BIP while raising the heat generated across the BIPs. Increasing the PSR slows the combustion while BIP speeds up the process. BIP and PSR show great trade-off reduction ability among all emission parameters. The optimum unburned hydrocarbon, nitrogen oxide, particulate, and carbon monoxide emissions for the injection at the valve were found to be 109.58, 0.577, and 2.336 ppm, and 0.103%, respectively, at low-load, low-BIP, and high-PSR. The emissions were lowered by 6.58, 91.26, 80.65, and 13.45% compared to the premixed RCCI mode, respectively. Therefore, introducing lowpressure biogas amid high swirling air at the valve elevates the in-cylinder condition while lowering the emissions, mitigating their environmental implications.