Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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  • Article
    Synthesis of Nannochloropsis Oculata Cultivation Process Based on Mixed-Integer Formulations
    (Elsevier, 2025) Kivanc, Sercan; Tuncer, Basak; Deliismail, Ozgun; Sildir, Hasan
    Sophisticated mathematical formulations and related optimization tasks are important to favor microalgae processing. This study focuses on the development of a mixed integer nonlinear programming approach to calculate design and operational decisions through simultaneous and rigorous approach under set of complex constraints and objective functions. Through a set of differential algebraic equations, whose model parameters are obtained through fitting a dataset available in the literature, three case studies are demonstrated for the calculation of optimum cultivation conditions based on economic considerations and biomass production. The case studies show the impact of the approach for the sustainability of the process as different conditions are primary defined by light color, reactor size, dilution rate, feed stream composition, and growing medium are required for desired tasks. The approach is flexible and further modifiable to various considerations for more complex decision-making problems.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    Emerging Trends of Biohydrogen Ecosystem on Environmental Sustainability: a Case Study
    (Elsevier Sci Ltd, 2025) Goren, A. Yagmur; Dincer, Ibrahim
    The greatest threat to humanity is now considered climate change. Biomass as a renewable energy source is treated as one of the clean energy sources that help meet humanity's energy needs. In the transition to a new energy system based on renewable energies, biomass can be crucial. This paper particularly focuses on a new biohydrogen (bioH2) ecosystem development concept for communities to provide global and local sustainable and green energy, considering the biomass-to-bioenergy nexus. In this regard, the paper further discusses the different bioH2 ecosystem concepts and emerging trends where biomass and renewable resources are utilized for energy production. In addition, the bioenergy production potentials of different agricultural crop wastes are evaluated for different end-use purposes like electricity, heat, cogeneration, and transport. In parallel to its high bioenergy yield, the highest total energy (83,686.8 GJ) and gross electricity (4686.5 MWh) production values were observed for the olive cake waste. Moreover, the biomethane and bioethanol production potentials of the crop wastes are evaluated. The highest biomethane yield of 253.7 m3/ha with a total bioenergy production of 40,662.6 GJ was obtained for the maize stover waste, while its bioethanol production was 505.7 L/ha. Consequently, the bioH2 ecosystem with biomass utilization reveales as a sustainable and green way of providing future energy for communities owing to the great potential of crop wastes for bioenergy production.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Small Wins in Practice: Learnings From 16 European Initiatives Working Towards the Transformation of Urban Food Systems
    (Elsevier Sci Ltd, 2024) Rao, Madhura; Luger, Jonathan; Regeer, Barbara J.; Lopez, Cristina Yacoub; Wilde, Danielle; Wilde, David; vander Meij, Marjoleine G.
    In this study, we examine how 16 initiatives across Europe are addressing 'wicked' food system issues by mobilising local networks and implementing small-scale but impactful changes in urban and peri-urban regions. To map the potential of these initiatives to contribute to large-scale change, we apply the Small Wins Framework proposed by Termeer & Dewulf (2019). By analysing data collected through interviews with participants working on initiatives spanning 13 cities across 9 European countries, we identify the manifestation of six propelling mechanisms that signal the capacity of small wins to bring about systemic change. Findings from this study reveal the presence of most mechanisms across the included initiatives. However, the ways in which these mechanisms appear depend on various factors such as stakeholder motivation, the maturity of the initiative, the need for additional funding, local food culture, and the regional and national political landscape among others. Our analysis indicates that the Small Wins Framework could be successfully used as a mapping tool in urban transformation processes, but it is likely to be more effective as a tool for reflexive monitoring rather than ex-post evaluation. Drawing on the impacts of various large-scale disruptions on the initiatives, we suggest that social, political, and economic shocks can present windows of opportunity to accelerate change and that initiatives performing well under such pressure should be supported in their pursuit of systems transformation. Lastly, we recommend non-linear growth strategies such as spreading, deepening, and expanding, as ways to compound the impact of small wins.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Integration of Daylight Use and Analysis in Double Skin Facades: a Literature Review
    (Gazi Universitesi, 2024) Kazanasmaz, Tugce; Ünlütürk, Mustafa Serhan
    Double skin facades (DSF) aim to save energy reducing the heat losses in buildings. They are visually appeal while allowing to use daylight efficiently. Such facade systems can reduce glare and distribute daylight evenly in the interior when compared to conventional facade systems. That is a result of cavities between two glass facades and locating sun shading elements in them, although this system provides a high level of transparency. As their primary purpose of application is to ensure thermal performance and ventilation, most studies in literature have focused on these. This study started with the hypothesis that studies examining daylight performance in DSFs are more limited than studies examining thermal performance and that daylight optimization methods are not used sufficiently in DSFs. In this context, the study aims to analyze studies focusing on daylight performance of DSFs. The review targets results of such current studies to guide future ones providing feedback knowledge. This may help to better technical developments in such facades and make them prevail in constructions or in retrofitting So, it contributes to literature in this sense. Recent studies are shown in tabulated form and interpreted in detail with graphics. considering their methodologies, daylight parameters and findings. Results show that the daylight parameter is one of the most important issues that architects or designers should consider from the moment they start the design, and they should make their designs based on the optimum penetration of daylight into the building. Consequently, this review presents that the use of daylight optimization has started to be used in recent studies dealing with DSFs. A DSF design can optimally get daylight into the interior can be made by using this method more frequently.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    High Skid-Resistant Pavements: the Effect of Gritting Parameters
    (Springer int Publ Ag, 2024) Gokalp, Islam; Uz, Volkan Emre; Saltan, Mehmet
    Turkey's Highway Technical Specification (HTS) necessitates gritting of pavement surface courses for the regions where the high-polishing resistant aggregate (PSV >= 50) is lacking or hard to reach. The gritting is defined as the spreading of 1-3 mm magmatic origin aggregates with the rate of 1.5-2 kg/m2 to the pavement surface after the roller's first pass. This study investigates the effect of gritting construction parameters (aggregate type, size, amount, and time of spreading) on pavement surface texture and skid resistance by monitoring the performance of nine test sections over more than three years under real traffic and environmental conditions. Considering the field observations, reduction in skid resistance with respect to traffic, in terms of equivalent standard axle load, is modeled for all test sections, and their service life is calculated. The results show that test sections gritted with the slag-origin aggregates perform better and yield nearly twice the service life of the one specified in the HTS. Accordingly, using slags in pavement gritting would provide safer and more sustainable highways.
  • 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.
  • Review
    Citation - WoS: 22
    Citation - Scopus: 30
    Comparative Environmental Sustainability Assessment of Biohydrogen Production Methods
    (Elsevier, 2023) Goren, A. Yagmur; Dincer, Ibrahim; Khalvati, Ali; Gören, Ayşegül Yağmur; Dinçer, İbrahim
    As energy crisis is recognized as an increasingly serious concern, the topic on biohydrogen (bioH(2)) production, which is renewable and eco-friendly, appears to be a highly-demanding subject. Although bioH(2) production technologies are still at the developmental stage, there are many reported works available on lab- and pilot-scale systems with a promising future. This paper presents various potential methods of bioH(2) production using biomass resources and comparatively assesses them for environmental impacts with a special emphasis on the specific biological processes. The environmental impact factors are then normalized with the feature scaling and normalization methods to evaluate the environmental sustainability dimensions of each bioH(2) production method. The results reveals that the photofermentation (PF) process is more environmentally sustainable than the other investigated biological and thermochemical processes, in terms of emissions, water-fossil-mineral uses, and health issues. The global warming potential (GWP) and acidification potential (AP) for the PF process are then found to be 1.88 kg-CO2 eq. and 3.61 g-SO2 eq., which become the lowest among all processes, including renewable energy-based H-2 production processes. However, the dark fermentation-microbial electrolysis cell (DF-MEC) hybrid process is considered the most environmentally harmful technique, with the highest GWP value of 14.6 kg-CO2 eq. due to their superior electricity and heat requirements. The water conception potential (WCP) of 84.5 m(3) and water scarcity footprint (WSF) of 3632.9 m(3) for the DF-MEC process is also the highest compared to all other processes due to the huge amount of wastewater formation potential of the system. Finally, the overall rankings confirm that biological processes are primarily promising candidates to produce bioH(2) from an environmentally friendly point of view.
  • Review
    Citation - WoS: 10
    Citation - Scopus: 14
    A Review on Characterization and Recyclability of Pharmaceutical Blisters
    (Elsevier, 2023) Capkin, Irem Yaren; Gokelma, Mertol
    Packaging is one of the biggest sectors in the world and the use of aluminium is widespread in the packaging industry. Pharmaceutical blister packages generate a significant amount of solid waste, typically containing plastics and aluminium as thin layers. Since these packages have a complex structure with multiple layers, they are hard to recycle. A separation process of the plastic and aluminium is needed prior to recycling. Hydrometallurgical or thermal processes can be used for the separation. This work reviews the characterization of different types of blisters and the different reagents used in the separation process of the blister layers. Parameters and results of separation processes by using hydrochloric acid, formic acid, acetic acid, organic solvents, and phosphoric acid were discussed as well as the thermal degradation.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Exergetic Assessment of an Solar Powered Stand-Alone System Using Liquid Organic Hydrogen Carrier for Energy Storage
    (Elsevier, 2023) Palmero-Marrero, Ana I.; Zairov, Rüstem; Borge-Diez, David; Çağlar, Başar; Açıkkalp, Emin; Altuntaş, Önder
    The integration of energy storage technologies into renewable energy systems has gained increasing attention for continuous supply of the renewable-based enegy. Among different storage alternatives, the use of a Liquid Organic Hydrogen Carrier (LOHC) has a significant potential as a reversible energy carrier for short and longterm energy storage. In this study, the technical and economic performance of an stand-alone renewable energy systems using a LOHC for energy storage have been evaluated by exergy-based methods in addition to simple energy and economic analysis. The analysis of the LOHC-free system was also included to determine the effect of LOHC on the system performance. The system containing phovoltaic (PV) panels, an electrolyzer, a micro gas turbine and hydrogenation/dehydrogenation LOHC units was designed to meet the power, heating and cooling requirement of a residential building. The system modelling and performance evaluation were made by using TRNSYS and EES softwares. Results show that the LOHC-containing system has higher energy and exergy efficiencies and exergoeconomic performance than the LOHC-free system while the latter is economically more feasible than the former due to its low capital investment cost.
  • Review
    Citation - WoS: 18
    Citation - Scopus: 18
    A Review on New Cobalt-Free Cathode Materials for Reversible Solid Oxide Fuel Cells
    (Chulalongkorn Univ, Metallurgy & Materials Science Research Inst, 2023) Akkurt, Sedat; Sındırac, Can; Özmen Egesoy, Tuğce; Ergen, Emre
    The exponential growth in the requirement of fuel cells and batteries leads to increased demand for cobalt due to its common use in high-performance Li-ion batteries and high-temperature fuel cells/electrolyzers. This sharp increment in demand raises concern about the availability of limited reserves of cobalt which can impact the price of cobalt. Moreover, the geographic limitations of cobalt resources may endanger the whole supply chain. In addition to all those, huge moral issues of cobalt mining are also another problem. Hence, leading battery, fuel cells and electrolyzer manufacturers are looking for sustainable alternatives to reduce cobalt dependency. A more specific limitation is shown in Solid Oxide Fuel Cells (SOFCs) cathode materials that contain cobalt. Incompatibilities have already been observed between the cathode materials containing cobalt and the electrolytes in terms of the thermal expansion coefficient mismatch during the transition of the operating temperature from high to low. An advantage of low operating temperatures is the reduction of material costs compared to high temperature. Increasing the electrochemical performance of the cell and eliminating thermal expansion coefficient difference problems are in concert aimed at the development of cobalt-free cathode materials. Therefore, cobalt-free cathode materials are vital for the sustainability of SOFCs and green transition of the energy sector since they can be used as cathode and anode material in symmetrical SOFCs which is also known as reversible SOFC (RSOFC). In this review, we comprehensively summarize the recent advances of cobalt-free perovskite cathode materials for intermediate temperature RSOFCs.