Papers by Gokcen Alev Ciftcioglu
Climate change, caused primarily by fossil fuels used for meeting the increasing energy demand, h... more Climate change, caused primarily by fossil fuels used for meeting the increasing energy demand, has become a global concern during the last decade. One of the most important sectors contributing to this demand is transport fuel production. To respond to this global challenge, all parties need to work in an identical pattern, i.e., socially appropriate, technically feasible, economically sustainable, and environmentally friendly. Specifically, the oil refining industry uses vast amounts of raw materials and creates considerable waste that needs to be processed, mainly at refinery sites from where most of the life cycle environmental burdens of all transport fuel types stem. This study compares two different types of crude oil used in Sudan refineries, namely X and Y blend crude oil, in terms of environmental impacts. A detailed Life Cycle Assessment (LCA) defined by the ISO14040/14044 frameworks was carried out via SimaPro software v.8.1.1.16. Both midpoint and endpoint approaches were adopted for the ReCiPe impact assessment method. Based on the selected midpoint impact categories, i.e., climate change, ozone depletion, human toxicity, and terrestrial acidification, the X crude oil impact scores were 282.7 kg CO 2 eq, 2.45E-06 kg CFC-11 eq, 1.05 kg 1,4-DB eq, and 0.145 kg SO 2 eq while the Y crude oil scores were 265.9 kg CO 2 eq, 1.58E-06 kg CFC-11 eq, 0.735 kg 1,4-DB eq, and 0.095 kg SO 2 eq, respectively. From an endpoint approach considering the representative single scores, overall impacts for the X and Y crude oil created an environmental load output of 13.8 and 12.7 Pt, respectively. As expected, both types of crude oil had a direct impact on the environment, where crude oil Y was found to have 10% less impact than crude oil X.
v 3.1. Stereolithography 31 3.1.1. Applications of stereolithography 3.1.2. Research on stereolit... more v 3.1. Stereolithography 31 3.1.1. Applications of stereolithography 3.1.2. Research on stereolithography 3.2. Microrheology 38 3.2.1. Theory of passive microrheology 3.2.2. Determination of the gel point 4. EXPERIMENTAL STUDIES 47 4.1. Materials Used in the Experimental Studies 47 4.2. Stereolithography Experiments 50 4.3. Microrheology Experiments 51 4.3.1. Sample preparation 4.3.2. Experimental setup 4.3.3. Experimental work 4.4. FTIR Experiments 57 4.5. DSC Experiments 59 5. RESULTS AND DISCUSSION 61 5.1. Deterministic Model Development for Simulation of Photopolymerization Process Conducted in SLA 61 5.1.1. Simulation of photopolymerization process conducted in SLA 5.1.2. Results of experiments 5.1.3. Comparison of experimental and simulation results 5.2. Simulation of Microrheology Measurements 83 5.2.1. Modification of PDE model for microrheology measurements 5.2.2. Effect of UV light penetration depth on the gelation time and simulation of the results 5.2.3. Effect of UV light wavelength and intensity on the gelation time and simulation of the results 5.2.4. Effect of photoinitiator loading concentration and oxygen inhibition on the gelation time and simulation of the results vi 5.3. Model Development for the Simulation of Deoxygenated Microrheology Measurements by using Ordinary Differential Equations 5.3.1. Comparison of experimental, 1-D PDE and ODE model simulation results 103 5.4. Simulation of Deoxygenated Microrheology Measurements by Stochastic Monte Carlo Model 5.4.1. Stochastic Monte Carlo model 106 5.4.2. Application of stochastic Monte Carlo model to photopolymerization process 114 5.4.3. Conversion of deterministic rate constants to stochastic rate constants 119 5.4.4. Comparison of stochastic Monte Carlo simulations and experimental results 121 5.4.5. Comparison of the deterministic (1-D PDE and ODE) and stochastic simulation results 126 5.5. Validation of Stochastic Monte Carlo Model 5.5.1. Validation by FTIR measurements 130 5.5.2. Validation by DSC measurements 135
İTÜ Dergisi Seri D: Mühendislik, 2010
DergiPark (Istanbul University), Nov 25, 2011
Due to the sporadic characteristics of solar and wind power it has been a challenge to generate a... more Due to the sporadic characteristics of solar and wind power it has been a challenge to generate a highly reliable power with photovoltaic and or wind turbines alone. A fuel cell as a supplementary energy source is an alternative to overcome this challenge. PV/wind/fuel cell hybrid power system may be a feasible solution for stand-alone applications. In this study, which is a preliminary work of a comprehensive Life Cycle Assessment (LCA), comparison of the power generation alternatives in terms of environmental impacts by evaluating their environmental and energy efficiencies and impacts during the productions of the system components was given. Also, impacts during the production of wind turbines, PV panels, fuel cells and diesel generators were inspected. Eco-Indicator 99 impact assessment method was used as the impact assessment method. It was shown that the in human health and ecosystem quality damage categories the PV panels are less environmentally efficient when compared with other power generation technologies with similar capacities.
A Preliminary Environmental Assessment of Power Generation Systems for a Stand-Alone Mobile House with Cradle to Gate Approach
Simulation of models for multifunctional photopolymerization kinetics
Polymer Engineering and Science, Aug 2, 2013
In this study, two different models of photopolymerization of multifunctional monomers are develo... more In this study, two different models of photopolymerization of multifunctional monomers are developed. The first is a kinetic model and is based on first order nonlinear ordinary differential equations describing the rates of photoinitiator, monomer, and live and dead radicals of different chain lengths. In the second model, a stochastic Monte Carlo approach is used to predict the time evolution of the photopolymerization process. In this model the chain affects are incorporated both in the propagation and termination rate constants. The simulations of these models for the predictions of gelation times are compared with the experimental values measured in the absence of oxygen in the reaction volume by using passive microrheology technique. The nonlinear decrease of gelation time with increasing photoinitator concentration and number of acrylate fragments on each monomer is best captured with the second model. Furthermore, the second model is successfully verified with kinetic data generated from FTIR and DSC experiments. POLYM. ENG. SCI., 54:1737–1746, 2014. © 2013 Society of Plastics Engineers
Life cycle assessment (LCA) of a solar selective surface produced by continuous process and solar flat collectors
Solar Energy, Oct 1, 2016
Abstract Roll to roll (R2R) continuous production of solar selective surface, is a cost benefit m... more Abstract Roll to roll (R2R) continuous production of solar selective surface, is a cost benefit method from the energy dispenses and investment point of view, therefore it is an innovative production way. Before innovative energy systems are introduced into the market, a thorough investigation of ecological aspect is necessary. Therefore, the purpose of this study is not only to perform a life cycle assessment (LCA) and demonstrate the advantage of the life cycle thinking selective surface production process, but also as to show the effect of this production method on the manufacturing process of solar flat collectors. LCA calculations for the continuous selective surface production process and a complete solar collector were performed with using the Ecoinvent database and the build in methods in SimaPro7.3: (1) Cumulative Energy Demand (CED); (2) Greenhouse Gas Protocol (GHG); (3) the Eco-indicator 99. To reflect the total quantity of primary energy needed to produce, use, and recycle/dispose of the produced selective surface—including transportation, CED was used. CED reflects the energy demand over its entire lifecycle, and makes it possible to determine which phase consumes the most energy. In order to quantify the greenhouse gas amount, the GHG was chosen since it is the most widely used and trusted international accounting tool. At last, the environmental impact of the system in study was calculated using Eco-indicator 99 method. The CED analysis estimated a yearly demand of 7.91 TJ for 200,000 square meter net selective surface production. Further calculations also showed that the energy payback time for the innovative production is as short as 3–4 days. Cu sheet production showed the highest impact and resulted in having the highest energy demand. The coating process only requires 32% of the primary energy demand. It was found that the energy demand of the plant and the building were as low as 2%, whereas it had 20% of GHG emissions. Further the total CO 2 equivalent was shown to be 0.3245 kg/m 2 . At last, the LCA for a complete solar collector having 4 m 2 of solar surface produced by conventional batch system and continuous roll to roll selective surface system was compared. The results also showed that using the roll to roll production technology caused reductions on the environmental burden. The results of LCA for the production of a continuous selective surface and comparison of solar flat collectors using two different selective surface production technology were presented. The energy payback time for the roll to roll selective surface production was found to be 3–4 days. The continuous process technology was shown to have a lower impact than the conventional batch selective surface production.
Resources Conservation and Recycling, Feb 1, 2016
Source-separated collection of recyclable packaging wastes has been a huge issue for cities such ... more Source-separated collection of recyclable packaging wastes has been a huge issue for cities such as Istanbul considering their socially, economically, culturally and environmentally cosmopolite structure. In order to apply an environmentally effective separation and collection, system has to be analyzed with a holistic approach including whole recycled packaging material amounts, source consumptions and related emissions. In this context, the aim of this study is to determine the environmentally optimum source-separated packaging waste collection system applicable in Istanbul, Turkey for the first time in literature. Eight scenarios for separated collection system were defined and all of them were compared with each other and with the existing system. To measure the efficiency of the system, some efficiency indicators were chosen and effectiveness related variables were determined to predict the participation rate. Calculations of the efficiency indicators for alternative scenarios were based on the existing system. The environmental analysis was conducted by using Life Cycle Assessment methodology. The results of this study showed that existing system was still one of the environmentally most promising scenarios. Following advantageous scenarios were Scenarios 5 and 6 which were two and three fractionated curbside collection systems, respectively. It is also seen that more fractionated scenarios were less beneficial than two fractionated scenarios. And finally, it can be concluded that with an increment on participation rate and changing collection material type, collection efficiency of curbside system would increase and be environmentally more beneficial.
Resources Conservation and Recycling, Sep 1, 2017
Recycling is one of the most preferable tools of the sustainability concept considering its econo... more Recycling is one of the most preferable tools of the sustainability concept considering its economic benefits and environmental effects. However, environmental and economic benefits are not always enough to accomplish a sustainable life concept. Social impacts, which basically focus on issues such as the well-being of humans, should be also considered. Regarding this concept; in this study we aimed to analyze the social impacts of different packaging waste management systems. In this context, we proposed eleven scenarios, which consisted of hypothetical formal and informal collection scenarios. All these scenarios were compared with the currently applied collection system in Istanbul, Turkey. The social analysis was conducted by using Life Cycle Assessment methodology. The results of this study showed that existing system and informal collection scenarios had socially fewer score than the formal scenarios in almost all impacts. Between the formal collection systems, there were slight differences caused by especially working conditions and socioeconomic repercussion. However, formal collection scenarios showed more negative social impacts than formal-informal system integration. The result of this study showed that it was crucial to consider an amelioration on the informal collection system. In the integrated scenario (S11), some of the critical subcategories were idealized and improved taking into consideration to the long term modification issues. Although we couldn't minimize all negative social impacts; it was obvious that this scenario was still the best option. Finally, we may conclude that application of an ameliorated informal collection system would be socially more beneficial than formal and informal collection systems.
Resources Conservation and Recycling, Apr 1, 2019
Considering the social, cultural, economic and environmental structure, source-separated collecti... more Considering the social, cultural, economic and environmental structure, source-separated collection of recyclable packaging wastes has been a huge issue for cosmopolite cities like Istanbul. To provide an effective recycling system; all source separation, collection and recycling activities should be analyzed environmentally and socially. In the scope of this study, existing and alternative municipal packaging waste management systems are analyzed and compared in terms of environmental and social impacts. The research is mainly based on a long term site observation, data collection and existing system analysis. Environmental performances of alternative scenarios are calculated based on the existing system data, whereas more site observations and interviews with stakeholders are conducted for the determination of social impacts. In the analysis of both environmental and social impacts of the scenarios, life cycle assessment used as a methodological approach. Results of the study show that informal collection systems are environmentally more effective than the formal collection systems. Even the resource consumption is high in these systems; they are still environmentally beneficial because of the high material collection rate. On the other hand, social impact assessment results indicate that informal collection system has serious social disadvantages compared to the formal systems. And finally, it is found that environmental and social weaknesses of the system could be minimized with integrated system applications.
Access to the published version may require subscription. N.B. When citing this work, cite the or... more Access to the published version may require subscription. N.B. When citing this work, cite the original published paper.
Polymer Engineering and Science, Jul 15, 2011
In this study, the effect of photoinitiator concentration on the gelation time of different resin... more In this study, the effect of photoinitiator concentration on the gelation time of different resins were studied in the absence of oxygen in the reaction volume by using passive microrheology technique. Four different monomers which are ethoxylated pentaerythritol tetraacrylate (SR494), trimethylolpropane triacrylate (SR351), triethylene glycol diacrylate (SR272), and 2(2-ethoxyetoxy) ethyl acrylate (SR256) were used in these experiments. Resins were prepared from these four different monomers by mixing them with various amount of 2,2-dimethoxy 1,2-diphenylethanone photoinitiator molecule with high absorption coefficient at the frequency of UV light used in these experiment. The simulations of the results obtained from microrheology experiments were carried out with the new model based on the stochastic Monte Carlo approach in order to account for the inherently random and discrete nature of the photopolymerization reactions. The model captures the nonlinear decrease of gelation time with increasing photoinitator concentration and number of acrylate fragments on each monomer.
Sustainability, May 17, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International journal of advances in engineering and pure sciences, Dec 30, 2021
Ambalaj atıklarının geri dönüşümü hem ekonomik hem de çevresel avantajlarından dolayı hızla artan... more Ambalaj atıklarının geri dönüşümü hem ekonomik hem de çevresel avantajlarından dolayı hızla artan atık üretimine karşı alınacak önlemleri destekleyebilecek önemli bir çalışma alanıdır. Maltepe Belediyesi ile ortaklaşa yürütülen bu çalışma; çevresel, sosyal ve ekonomik açıdan en uygun olan ambalaj atığı toplama sisteminin geliştirilmesini amaçlamaktadır. Bu kapsamda; mevcut ambalaj atığı toplama sistemi ve bu sisteme alternatif olarak geliştirilen 6 farklı toplama sistemi incelenmiştir. Toplama sistemlerinin sürdürülebilirlik analizinde yaşam döngüsü değerlendirmesi metodu kullanılmıştır. Yaşam döngüsü değerlendirmesinde kullanılacak olan envanter verileri; mevcut sistem analizi, saha gözlemi, anketler ve alternatif sistem hesaplamaları sonucunda elde edilmiştir. Alternatif senaryoların çevresel ve ekonomik analizi mevcut sistem verileri dikkate alınarak hesaplanırken; sosyal analiz, saha gözlemleri ve anketlere dayandırılarak yapılmıştır. Bu çalışmanın sonunda, çevresel ve ekonomik açıdan değerlendirme yapıldığında resmi toplama sistemine kıyasla, kayıt dışı toplama sisteminin daha avantajlı olduğu görülmüştür. Ancak sosyal analiz sonuçları irdelendiğinde kontrolsüz toplama sistemlerinin ciddi bir dezavantaja sahip olduğu tespit edilmiş, bütünleyici bir bakış açısına ihtiyaç olduğu açıkça görülmüştür. Bütüncül bir perspektifle yürütülen çevresel, sosyal ve ekonomik analiz neticesinde ortaya çıkarılan zayıflıkların, resmi ve kayıt dışı sistem entegrasyonunun önerildiği alternatif toplama sistemiyle minimize edilebileceği öngörülmüştür.
Journal Of Environmental Science And Health, Part A, Sep 1, 2006
The sulfation experiments of the slurries prepared by using natural trona (NaHCO 3 .Na 2 CO 3 .2H... more The sulfation experiments of the slurries prepared by using natural trona (NaHCO 3 .Na 2 CO 3 .2H 2 O) originating from the Beypazarı-Ankara region of Turkey were performed at different conditions. A statistical design technique was applied by the use of a two-level factorial design matrix to interpret experimental results. Sulfation conditions were selected according to a two-level factorial design matrix considering the following variables: sulfation time (3 and 7 h), sorbent content of slurry (1 % and 3 %) and sulfation temperature (298 and 323 K). It was found that the sorbent content of slurry has the strongest effect on the total sulfation capacity in comparison with sulfation time and temperature. The effects of different magnesium and calcium salts on the total sulfation capacities of trona slurries were also investigated. The total sulfation capacities of slurries were increased from 11.45 to 33.00 (mg SO 3 /mL slurry) and from 21.25 to 25.80 (mg SO 3 /mL slurry) with the addition of magnesium and calcium salts, respectively.
Acta Physica Polonica A, 2015
Catalysis plays a critical role in the accomplishment of industrially significant chemical transf... more Catalysis plays a critical role in the accomplishment of industrially significant chemical transformations, by requiring less energy investment in underlying processes. Computational chemistry has had a pronounced impact on the understanding of the role of catalysts at the atomic and molecular level, contributing to design of more efficient catalysts. In this study, we compute thermochemical properties attending C-H bond activation of methane by OsO + and enabling subsequent dehydrogenation and dehydration reactions. It is found that the dehydrogenation channel is thermodynamically more favorable. This study should contribute to the understanding of C-H bond activation using homogeneous catalysis of partial oxidation of natural gas (methane) leading to formation of the easily transported liquid fuel methanol.
Solar energy, since it is available every day, is seen as one of the most valuable renewable ener... more Solar energy, since it is available every day, is seen as one of the most valuable renewable energy resources. Thus, the energy of sun should be efficiently used in various applications. The most known applications that use solar energy are heating water and spaces. High efficiency solar collectors need appropriate selective surfaces to absorb the heat. Selective surfaces (Selektif-Sera) used in this study are applied to flat collectors, which are produced by a roll to roll cost effective coating of nano nickel layers, developed in Selektif Teknoloji Co. Inc. Efficiency of flat collectors using Selektif-Sera absorbers are calculated in collaboration with Institute for Solar Technik Rapperswil, Switzerland. The main cause of high energy consumption in industry is mostly caused from low temperature level processes. There is considerable effort in research to minimize the energy use by renewable energy sources such as solar energy. A feasibility study will be presented to obtain the po...
Molecules, 2021
Understanding the impact of different bridging groups in the two-step polymerization of poly(ethy... more Understanding the impact of different bridging groups in the two-step polymerization of poly(ethylene glycol) (PEG)-incorporated polyimide (PI) materials is significant. It is known that the proton exchange membranes (PEMs) used in industry today can experience performance degradation under rising temperature conditions. Many efforts have been devoted to overcoming this problem by improving the physical and mechanical properties that extend the hygrothermal life of a PEM. This work examines the effect of oxygenated and fluorinated bridging anhydrides in the production of PI-PEG PEMs. It is shown that the dianhydride identity and the amount incorporated in the synthesis influences the properties of the segmented block copolymer (SBC) membranes, such as increased ionic liquid uptake (ILU), enhanced conductivity and higher Young’s modulus favoring stiffness comparable to Nafion 115, an industrial standard. Investigations on the ionic conductivity of PI-PEG membranes were carried out to...
International Journal of Information and Education Technology, 2017
Life is an excellent laboratory to understand, comprehend and master the basic sciences. The theo... more Life is an excellent laboratory to understand, comprehend and master the basic sciences. The theoretical principle underlying the daily life phenomena has a potential to assist education. With this point of view, some examples were offered to use in engineering education, especially for chemical engineering departments, to ease the understanding and mastering of the undergraduate students. In order to check this educational approach, a questionnaire was performed among the students taking the lecture with the notion mentioned in this study and students not taking the course. The evaluation of the questionnaire proved that the daily life examples can enhance learning.
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Papers by Gokcen Alev Ciftcioglu