Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Now showing 1 - 10 of 19
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    CFD-DEM Modeling of Biomass Pyrolysis in a DBD Plasma Fluidized Bed
    (Pergamon-Elsevier Science Ltd, 2025) Eslami, Ali; Kazemi, Saman; Hamidani, Golnaz; Zarghami, Reza; Mostoufi, Navid
    This study developed a CFD-DEM model to simulate biomass pyrolysis within a dielectric barrier discharge (DBD) plasma fluidized bed reactor. Biomass, as a renewable energy source, offers a promising alternative for hydrogen production through pyrolysis. The integration of non-thermal plasma technology and fluidized bed reactors is expected to enhance conversion. Key operational parameters such as inlet gas velocity, particle size, and input voltage were examined to evaluate their effects on temperature distribution, particle conversion, and hydrogen production. Results indicated that higher inlet gas velocities promote better particle mixing and more uniform temperature and conversion distribution. Smaller particle sizes significantly enhance biomass conversion by increasing the available surface area between fluid and particles. Specifically, particles with diameters of 0.85, 1.2, and 1.5 mm achieved conversions of 10.4, 8.99, and 8.57 %, respectively, at 20 s from the start of the process. Additionally, increasing the input voltage increases the mean temperatures of particles and fluid, which enhances reaction rates and conversion. Optimizing these parameters can improve the efficiency of DBD plasmaassisted biomass pyrolysis, providing valuable insights for sustainable hydrogen production.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 1
    Enhancing Biomass Pyrolysis via Microwave Heating: A CFD-DEM Study on Intensification in Fluidized Beds
    (Elsevier Sci Ltd, 2026) Hamidani, Golnaz; Kazemi, Saman; Eslami, Ali; Zarghami, Reza; Sotudeh-Gharebagh, Rahmat; Mostoufi, Navid
    Biomass conversion into high-value products in fluidized beds can be significantly improved by utilizing microwave irradiation as the heating source. The present work studied microwave-assisted biomass pyrolysis using a coupled CFD-DEM model in a fluidized bed. The effect of key operating parameters, including inlet gas velocity (1.5, 2, and 2.5 times the minimum fluidization velocity), mean particle diameter (1.2, 1.3, and 1.5 mm), and microwave power input (200, 400, and 600 W), was evaluated on the performance of the reactor. The results revealed that higher microwave power increased the mean particle temperature and chemical conversion rate due to greater internal energy generation within the biomass particles. Increasing the gas velocity led to lower particle temperature because of enhanced convective heat transfer to the gas phase, and improved the uniformity of temperature and conversion distributions. Furthermore, decreasing the mean particle diameter from 1.5 to 1.2 mm increased the average temperature, from 890 to 987 K, and raised biomass conversion from 14.8 to 18.1 %, mainly by reducing convective heat losses. The validated model developed in this study enables accurate predictions of process behavior and provides valuable insights for optimizing microwave-assisted biomass pyrolysis in fluidized beds. These findings highlight the potential of microwave-assisted fluidized bed pyrolysis as an efficient technique for process intensification in producing valuable bio-based products.
  • Review
    Citation - Scopus: 5
    A Comparative Evaluation of Dark Fermentative Bioreactor Configurations for Enhanced Hydrogen Production
    (Springer, 2025) Gören, Ayşegül Yağmur; Dincer, I.; Khalvati, A.
    Energy from renewable resources has been growing in popularity, which ultimately helps reduce emissions of greenhouse gases (GHGs) and contaminants. Since hydrogen (H2) has a higher combustion production of energy than hydrocarbon fuels, it has been identified as a clean, sustainable, and environmentally friendly energy source. There are several benefits to producing biohydrogen (bioH2) from renewable sources, including lower cost and increased sustainability. Among the bioH2 production processes, dark fermentation supports commercialization and scale-up for industrial applications. This paper considers the various bioreactors, such as anaerobic sequencing batch, continuous stirred, up-flow, fixed-bed, and membrane reactors, and their operational approaches for bioH2 production. This review paper also performs the bibliometric analysis method to identify historical and current developments in a particular field of reactor configuration studies. Furthermore, the main variables influencing reactor performance and methods for increasing process efficiency considering economic and environmental aspects are addressed. The results revealed that continuously stirred reactors are widely utilized for bioH2 production as a cost-effective reactor configuration. Moreover, the membrane bioreactors and fixed-bed reactors are yielded higher bioH2 performance than other configurations. Nevertheless, high energy consumption and costs have presented the need for further development of reactors. Consequently, future recommendations to solve the critical problems faced in reactor configurations, the gaps in the literature, and the points that need improvement were comprehensively reported. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    A New Electro-Biomembrane Integrated Renewable-Based System To Produce Power, Fresh Water and Hydrogen for Sustainable Communities
    (Elsevier, 2025) Goren, A. Yagmur; Dincer, Ibrahim; Khalvati, Ali
    As the consequences of global warming become more severe, it is more crucial than ever to capitalize on all locally accessible potential renewable energy sources and produce sufficient useable energy outputs to meet community demands while causing the least damage to the ecosystem. Therefore, this paper focuses on a unique parabolic trough collector solar system-powered electro-biomembrane unit that combines a heat and power system with fresh water, electricity and hydrogen production. The proposed integrated system contains the following subsystems: a combining parabolic trough collector solar system, an organic Rankine cycle, a steam Rankine cycle, a multi-stage flash desalination system, and an electro-biomembrane H2 and freshwater production system. A thorough analysis and parametric research are performed on the multigeneration system to determine how important characteristics affect system performance and evaluate the energy and exergy efficiencies, and exergy destruction levels for particular system elements. The study results show that solar irradiation is the most critical parameter for improving system performance. The highest freshwater production of 1,303,333.3 L/day is observed at the solar irradiation of 935,768 kWh/day. Furthermore, the combined output of three electricity production technologies exceeds 2,000,000 kWh/day, highlighting the ability of the system to harness solar thermal energy effectively. The study findings indicate that using solar power and biomass as renewable energy sources, the proposed integrated system provided 328.56 kg of biohydrogen per day. Overall, the energy and exergy efficiencies of the integrated system are obtained as 34.3 and 29.5 %, respectively.
  • Book Part
    Citation - Scopus: 3
    Future Trends of Hybrid Energy Systems
    (Elsevier, 2024) Taheri, M.H.; Seiiedhoseiny, M.; Mohammadpourfard, M.; Akkurt, G.G.
    Hybrid energy systems can be defined as a combination of at least two fuel sources or energy conversion equipment that, when combined, can eliminate the constraints related to every single component. In addition to the application of multiple renewable energy sources, the improvement of energy efficiency via multi-generation plants constitutes a significant share of the recent investigations, which would include a prominent part of the future trend in hybrid energy systems. The present chapter will review the pioneer works and tries to address the future of hybrid energy systems. © 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Hydrogen Production From Energetic Poplar and Waste Sludge by Electrohydrogenesis Using Membraneless Microbial Electrolysis Cells
    (Pergamon-elsevier Science Ltd, 2024) Goren, A. Yagmur; Kilicaslan, A. Faruk; Dincer, Ibrahim; Khalvati, Ali
    Membraneless microbial electrolysis cells (MECs) are potentially considered to produce biohydrogen (bioH2) in a green manner and simultaneously minimize agricultural and wastewater facility wastes. However, effective, sustainable, and cost-effective system configuration and improvement of operating variables, working at ambient conditions, are needed to make the MEC a sustainable process. Therefore, this study investigates the bioH2 production from poplar leaves and anaerobic sludge mixture by incorporating nanomaterials comprising Al2O3, MgO, and Fe2O3 metal oxides at various dosages. Moreover, the effects of applied cell voltage (0.5-1.5 V) and inoculum amount (20-40 mL) on bioH2 production and organic matter removal performance are evaluated. The maximum bioH2 production value is 417 mL at an applied voltage of 1.5 V with a chemical oxygen demand (COD) removal efficiency of 37.6 % under operating times of 5 min using 40 ml of inoculum. The bioH2 production of the MEC system is reduced with the decrease in inoculum amount. The highest bioH2 production of 828 mL is obtained at improved conditions in the presence of 1 g of Fe2O3 metal oxide. Overall, this study provides the potentiality of simultaneous waste minimization and bioH2 production under ambient conditions that highlight the waste-to-energy pathway for membraneless and green bioelectrochemical process.
  • Article
    Citation - Scopus: 5
    Ultrasound Assisted Extraction for the Recovery of Phenolic Compounds From Waste Hazelnut Shell
    (Yildiz Technical University, 2020) Dal,O.; Şengün,D.; Özşen,A.Y.
    Hazelnut shell is the primary byproduct of hazelnut industry which has the potential source of antioxidants, and phenolics with interest of pharmaceutical, food, and cosmetic industries. The main goal of this study is to determine effects of extraction method, extraction time, solvent type, solid to liquid ratio, and particle size on extraction yield, antioxidant capacity, and total phenolic content of waste hazelnut shell. The highest extraction yield was found as 15.4% by using methanol as solvent, in combined extraction for 16 h total extraction time. As for the best antioxidant capacity, 0.0508 mg TE mL-1 was observed by using methanol as a solvent in ultrasonic extraction, whereas the highest phenolic content was found as 0.188 mg GAE mL-1 by Soxhlet extraction with acetone for 8 h. After extraction of hazelnut shell waste, major components were found as oleic and palmitic acids for all solvent types according to GC-MS results. © Yildiz Technical University, Environmental Engineering Department. All rights reserved.
  • Book Part
    Citation - Scopus: 1
    Biomass-Based Polygeneration Systems With Hydrogen Production: a Concise Review and Case Study
    (Springer Science and Business Media Deutschland GmbH, 2024) Hajimohammadi Tabriz,Z.; Mohammadpourfard,M.; Gökçen Akkurt,G.; Çağlar,B.
    This chapter discusses the importance of biomass-based polygeneration systems in producing hydrogen as a clean and safe energy carrier. The benefits of polygeneration systems, which can produce multiple products and minimize waste, are highlighted, and the need for clean and efficient hydrogen production is emphasized. This study gives a brief overview of hydrogen production from biomass-based polygeneration systems, which examines the systems in two main classifications: systems that use biomass as a potential and rich source of hydrogen and systems that exploit the energy content of biomass to run hydrogen production units. Furthermore, a new multigeneration system with hydrogen production has been introduced and thermodynamically evaluated. Also, its results have been obtained in a real situation. Overall, this chapter offers insights into the potential of biomass-based polygeneration systems in meeting energy demands while reducing environmental impact. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 17
    Cleaner Production of Biohydrogen Using Poplar Leaves: Experimental and Optimization Studies
    (Elsevier Sci Ltd, 2024) Goren, A. Yagmur; Kenez, Muratcan; Dincer, Ibrahim; Khalvati, Ali
    Biohydrogen (bioH2) is recognized as a potential carbon-neutral energy vector, and developing novel methods has received increasing attention with a prime goal of producing H2 more efficient and cost effective manner. This study aimed to develop a unique reactor to investigate dark fermentative H2 production from poplar biomass using commercially available and inexpensive microorganism cultures. Therefore, six factors of the Box-Behnken design (BBD) were performed to evaluate the individual and combined effects of operational param-eters: acid concentration (2-10%), biomass concentration (2-10 g), initial pH (5-8), temperature (30-40 degrees C), mixing ratio (150-350 rpm), and microorganism concentration (2-6 g) on bioH2 production. Among the oper-ational parameters, the acid concentration was the most effective parameter on bioH2 production. The bioH2 production increased from 11.33 to 18.15 mg/g biomass with increasing acid concentration from 6 to 10%. Moreover, the optimum levels of operational variables were as follows: acid concentration of 9.9%, biomass amount of 2 g, pH of 6.56, temperature of 35 degrees C, mixing ratio of 345 rpm, and microorganism amount of 4.5 g for the highest bioH2 production of 20 mg/g-biomass according to the experimental design. Consequently, the bioH2 production performance of the dark fermentation process showed that bioH2 production from poplar biomass using commercially available microorganisms had a competitive advantage.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 5
    Breakthrough Curve Analysis of Phosphorylated Hazelnut Shell Waste in Column Operation for Continuous Harvesting of Lithium From Water
    (Elsevier, 2024) Recepoğlu, Yaşar Kemal; Arar, Ozguer; Yuksel, Asli
    In batch-scale operations, biosorption employing phosphorylated hazelnut shell waste (FHS) revealed excellent lithium removal and recovery efficiency. Scaling up and implementing packed bed column systems necessitates further design and performance optimization. Lithium biosorption via FHS was investigated utilizing a continuous-flow packed-bed column operated under various flow rates and bed heights to remove Li to ultra-low levels and recover it. The Li biosorption capacity of the FHS column was unaffected by the bed height, however, when the flow rate was increased, the capacity of the FHS column decreased. The breakthrough time, exhaustion time, and uptake capacity of the column bed increased with increasing column bed height, whereas they decreased with increasing influent flow rate. At flow rates of 0.25, 0.5, and 1.0 mL/min, bed volumes (BVs, mL solution/mL biosorbent) at the breakthrough point were found to be 477, 369, and 347, respectively, with the required BVs for total saturation point of 941, 911, and 829, while the total capacity was calculated as 22.29, 20.07, and 17.69 mg Li/g sorbent. In the 1.0, 1.5, and 2.0 cm height columns filled with FHS, the breakthrough times were 282, 366, and 433 min, respectively, whereas the periods required for saturation were 781, 897, and 1033 min. The three conventional breakthrough models of the Thomas, Yoon-Nelson, and Modified Dose-Response (MDR) were used to properly estimate the whole breakthrough behavior of the FHS column and the characteristic model parameters. Li's extremely favorable separation utilizing FHS was evidenced by the steep S-shape of the breakthrough curves for both parameters flow rate and bed height. The reusability of FHS was demonstrated by operating the packed bed column in multi-cycle mode, with no appreciable loss in column performance.