Yazar "Unalan, Sebahattin" seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A Novel Tea factory waste metal-free catalyst as promising supercapacitor electrode for hydrogen production and energy storage: A dual functional material(Elsevier Sci Ltd, 2021) Ozarslan, Saliha; Atelge, M. Rasit; Kaya, Mustafa; Unalan, SebahattinIn this study, the catalyst produced from tea factory waste (TFW) was used for the first time for hydrogen production by methanolysis of sodium borohydride (NaBH4). The produced material had a dual function as both catalyst and supercapacitor; therefore, it was named 'cap-cat'(capacitor-catalyst) by us. In this context, TFW was treated with acetic acid for 24 h at 80 degrees C. The sample was then subjected to combustion in the oven to synthesize the catalyst. Afterward, the most efficient TFW-CH3COOH catalyst was synthesized by evaluating different acid ratios, burning temperatures and times. The best conditions for the acetic acid ratio, burning temperature, and time were found out 3 M, 300 degrees C, and 60 min. The characterization of the catalyst was done using SEM-EDX, FTIR, XRD analysis. Hydrogen generation experiments from NaBH4 by methanolysis were performed at various catalyst concentrations in the range of 0.05-0.2 g, diverse NaBH4 ratio of 1 to 7.5%, and at different reaction temperatures (30-60 degrees C). The HGR of the synthesized catalyst was recorded as 3096.4, 8367.5, 11227.9, and 23,507 mLmin(-1)g(cat)(-1) for these temperatures (30, 40, 50, and 60 degrees C), respectively. Also the activation energy was calculated as 38.6 kJ mol(-1). Subsequently, the CV (cyclic voltammetry) and charge-discharge curves of the prototypes produced were substantially similar to the supercapacitor curves in the literature. Gravimetric capacitance was found to be 155F/g at a current density of 2 A/g.Öğe A REVIEW FOR ASSESSMENT METHODS OF BLACK TEA PRODUCTION WASTE(Begell House Inc., 2022) Ozarslan, Saliha; Rasit Atelge, M.; Kaya, Mustafa; Unalan, SebahattinTea production waste occurs during the production of black tea from fresh tea in tea factories, consisting of tea stalk, fiber, and powder, which are unused parts of the tea plant. Tea waste amounts may vary according to the quality of the production process and the harvesting of tea. However, a certain amount of tea waste is obtained every year in the countries that produce tea. Such a large and inexpensive biomass resource is not generally evaluated. There are several ways to take advantage of this biomass source and work on this subject is increasing. In this study, the methods of evaluating tea wastes were researched and the data obtained were transferred with their results. Studies collected under five main topics can be promising for the development of existing studies and new research. This study can be a guide for removing losses from the storage of tea waste and making this biomass economically valuable. © 2022 Begell House Inc.. All rights reserved.Öğe Evaluation of hybrid nanoparticles to oxygenated fuel with ethanol and n-butanol on combustion behavior(Elsevier Sci Ltd, 2023) Atelge, M. R.; Arslan, Esenay; Kahraman, Nafiz; Unalan, SebahattinThe internal combustion engine type is widely used in diesel engines due to its energy efficiency. However, the use of conventional diesel has negative effects on human health and the environment. In an effort to find a more sustainable fuel option with less harmful emissions, the focus has shifted towards investigating the effects of hybrid nano additives, which are a combination of nonmetallic (graphene nanoplate) and metal oxide (TiO2), on conventional diesel (D) and oxygenated fuels (OF). The engine test was conducted at 4 different loading cases with increments of 25% from 25% to 100% at a constant speed of 1500 rpm. The results showed that the modified fuels had superior combustion behaviors, such as peak in-cylinder pressure, combustion duration, and ignition delay, compared to conventional diesel and oxygenated fuels. The peak pressures in the cylinder of modified diesel (Dm) and modified oxygenated fuel (OFm) under full load increased by 2% and 2.9%, respectively, compared to conventional diesel (D). Additionally, the brake thermal efficiencies (BTEs) of Dm and OFm were found to be 5.5% and 3% higher than D under the same test conditions. In terms of emission analysis, the modified fuels demonstrated superiority over the conventional diesel and oxygenated fuels. During full load conditions, the CO, UHC, and NO emissions of OFm compared to D dropped by 49.1%, 54.2%, and 4%, respectively. The study results indicate that the use of a hybrid fuel additive consisting of nonmetallic (graphene nanoplate) and metal oxide (TiO2) can significantly reduce harmful emissions and improve engine performance.Öğe Examination of the effect on the engine of diesel-nanoparticle mixture with natural gas addition(Elsevier Sci Ltd, 2024) Arslan, Esenay; Atelge, M. Rasit; Kahraman, Nafiz; Unalan, Sebahattin; Ceper, Bilge A.Diesel engines have a broader application area and have a significant share in the transportation sector. Although there are restrictions on producing within the scope of emission standards, diesel fuel will remain important in heavy-duty vehicles for some time. Therefore, studies continue for environmentally friendly combustion and low emissions in diesel fuel. This paper reveals the results of using nanoparticle fuel with natural gas (NG) on diesel engine emissions and performance. In the experiments, the motor load was adjusted from no to full load by increasing it at 25% intervals. Three different diesel-nanoparticle blends containing 25 ppm, 50 ppm and 75 ppm carbon nanotube (CNT) were prepared and each of these blends was tested both with and without NG. In light of the test results, it has been seen that the D75ppmCNT + NG mixture is the best fuel mixture compared to both diesel and nanoparticle-added diesel since it provides the highest value in brake thermal efficiency (BTE) and the lowest value in brake specific fuel consumption (BSFC) at full load conditions. In the case of using a D75ppmCNT mixture, around 29% decrease in BSFC and about 28% increase in BTE were observed according to the diesel fuel use. In terms of emissions, when NG is added to the D + CNT fuel mixtures, there is an increment in CO and HC emissions and a slight reduction in NOx emissions at low and medium load.Öğe Investigation of H2 enrichment of ternary blended fuel modified with graphene nanoplate on cycle-by-cycle variations(Pergamon-Elsevier Science Ltd, 2024) Atelge, M. R.; Arslan, Esenay; Kahraman, Nafiz; Kaushal, Rajneesh; Unalan, SebahattinDespite the global goal of achieving e-mobility in the future, the majority of the transportation sector still heavily relies on fossil fuels. Previous studies in the area have revealed the benefits of hydrogen additives and nanoparticles mixed with blended diesel fuels on engine performance and emissions. However, there is a significant gap in the research when it comes to exploring the combination of non-metallic nanoparticle additives with alcohol and diesel blend fuels under dual-fuel mode with hydrogen. In the study, a fuel blend (BF) comprising 80% diesel, 10% n-butanol, and 10% ethanol, which represents a potential alternative fuel composition for compression ignition engines, was specifically focused on. To further enhance the fuel properties and combustion characteristics, the addition of 50 ppm graphene nanoplatelets (GNP) was introduced as a non-metallic additive. By examining this novel fuel composition and investigating its impact under both single and dual-fuel mode, the dimension of hydrogen addition in the dual-fuel mode is aimed to explore potential synergistic effects. A diesel engine was used under dual fuel mode, with hydrogen fed at a rate of 0.25 g/min. The prepared fuels were tested at 1800 rpm engine speed by applying five different loads. 50 ppm GNP of modified fuels resulted in an increase of peak pressures by 3.1%, 4.2%, and 5.6% for DGNP, BFGNP, and BFGNP15H respectively, compared to D. At full load, the COVIMEP values were approximately 0.3%, 0.2%, 0.4%, 1.3%, and 1.6% for D, DGNP, BF, BFGNP, and BFGNP15H, respectively. In the term of thermal efficiency, BFGNP15H had a 3.9% lower BTE than BFGNP at 25% load, but BFGNP15H showed a 0.4% increase in BTE at full load compared to BFGNP. For emission analysis, BFGNP15H showed a reduction of 42.31%, 15.1%, and 10% in CO emissions compared to D, BF, and BFGNP, respectively, under full load in dual operating condition. However, the NO emissions of BFGNP15H were 7.2% higher than those of D under the same condition.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Production of dual functional carbon material from biomass treated with NaOH for supercapacitor and catalyst(Wiley, 2021) Ozarslan, Saliha; Atelge, Muhammed Rasit; Kaya, Mustafa; Unalan, SebahattinIn this research, tea factory waste (TFW), an organic biomass source, was used as a metal free basic catalyst for the production of hydrogen from NaBH4 by methanolysis. In the preparation of the catalysts, tea factory wastes taken from the tea factory and released during tea production were used. For the production of H-2 from NaBH4 by methanolysis, TFW was pre-treated with different base materials (KOH, NH4Cl, and NaOH). Tests have been made on different mixing ratios, combustion temperatures, and durations for catalyst optimization by selecting the base with the highest hydrogen yield. Hydrogen production efficiency was recorded as 2832.2 and 6560.8 mL min(-1) g(-1) at 30 degrees C and 60 degrees C, respectively. The activation energy of the catalyst was defined as 18.07 kJ mol(-1). Characterization of TFW catalyst was examined by SEM-EDX, XRD, and FT-IR analysis. When the obtained data were evaluated and some studies available in the literature were considered, it was concluded that tea factory wastes, which are a biomass resource, can be used in catalyst production. The capacitance value of the electrode was computed as 8 to 12.9 F g(-1).
