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Öğe AHŞAP NUMUNELERİN PİROLİZİ İLE SENTEZ GAZI ELDESİNDE NEMİN ETKİSİ(Düzce Üniversitesi, 2017) Kılınçel, Mert; Toklu, Ethem; Gür, MahmutBu çalışmada belirli nem seviyelerindeki(%5-25) atıkahşap numuneleri laboratuvar ölçekli bir piroliz reaktöründe oksijensiz olarakbozundurularak, katı, sıvı ve gaz son ürünler olan sentez gazı, katran ve çar eldeedilmiştir. Piroliz son ürünlerini etkileyen önemli parametrelerden biri olannem içeriğindeki değişiminin sentez gazı oluşumuna etkisi incelenmiştir.Çalışmada kullanılan ahşap numuneler iki aşamalı kırma işlemine tabi tutularak 0,2mm-10mmboyutlarına kadar küçültülmüştür. Numunelerin piroliz işlemine hazır halegetirilebilmesi için bir ön kurutma işlemi gerekmektedir. Bu işlem içinkullanılan kurutma ünitesi ihtiyacı olan enerjiyi piroliz ünitesinin atıkısısından sağlamaktadır. Burada numunelerin verimli kurutulabilmesi için döneryataklı ve dâhili karıştırma fonksiyonu bulunan, 100-120 oC sıcaklıkdeğerlerine ulaşabilen bir kurutucu ünitesi kullanılmıştır. Döner kurutucunundönme devir hızına değiştirilerek farklı işlem sürelerinde farklı nemoranlarında numuneler elde edilmiştir. Buradan elde edilen üç farklı nemiçeriğindeki(%5, %15, %20 ve %25) ahşap numuneler 350-450°C arası sıcaklıkta piroliz edilerek elde edilen sentez gazı oluşumlarıkarşılaştırılmıştır. Piroliz işlemi sonucu ortaya çıkan sentez gazı oluşumlarıincelendiğinde nem içeriği düşük numunelerden daha yüksek debide gaz çıkışıolduğu belirlenmiştir.Öğe Biomass energy potential and utilization in Turkey(Pergamon-Elsevier Science Ltd, 2017) Toklu, EthemBiomass is the most widely used renewable energy source in the world today. It is used mostly in solid form and, to a lesser extent, in the form of liquid fuels and gas. The utilization of biomass for energy production has increased at only a modest rate in modern times. Biomass is the major source of energy in rural Turkey. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. Biomass potential includes wood, animal and plant wastes. Among the biomass energy sources, fuel wood seems to be the most interesting because its share of the total energy production of Turkey is high at 14%. The total biomass energy potential of Turkey is about 33 million tons of oil equivalents (Mtoe). The amount of usable biomass potential of Turkey is approximately 17 Mtoe. The electrical production potential from usable bioenergy sources are 73 MW in 2010 and corporate income and represent more than 280,000 jobs. This study shows that there is important biomass energy potential for climate change mitigation and energy sustainability in Turkey. (C) 2017 Elsevier Ltd. All rights reserved.Öğe The effect of outer container geometry on the thermal management of lithium-ion batteries with a combination of phase change material and metal foam(Elsevier, 2024) Kursun, Burak; Toklu, Ethem; Polat, Fikret; Balta, MehmetThe use of PCM for thermal management of the batteries has an important place among passive cooling methods because it does not require pump or fan power. In battery cooling applications with PCM, it was aimed to increase the thermal conductivity of the PCM and to cool the battery better by using fins, nanoparticles, and metal foam. The novelty of this study is to investigate the effect of outer container geometry on battery temperature in battery cooling with PCM + metal foam composition. In this direction, five different container geometries affecting the heat transfer by conduction and convection were analyzed. The parametric study was carried out for different values of convection heat transfer coefficient, heat generation in the battery, PCM amount, and porosity. The lowest battery temperature for a given discharge time was obtained in triangular container geometry. With the use of a triangular container, the battery temperature was reduced between 0.4 % and 14.42 % compared to the use of a circular container, depending on the parameter values. The analysis findings revealed that the outer container geometry is more effective in the thermal management of the battery for conditions with low convection heat transfer coefficient and high heat generation.Öğe FATIGUE LIFE PREDICTIONS OF METAL MATRIX COMPOSITES USING ARTIFICIAL NEURAL NETWORKS(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2014) Uygur, İlyas; Çiçek, Adem; Toklu, Ethem; Kara, Resul; Sarıdemir, SuatIn this study, fatigue life predictions for the various metal matrix composites, R ratios, notch geometries, and different temperatures have been performed by using artificial neural networks (ANN) approach. Input parameters of the model comprise various materials (M), such as particle size and volume fraction of reinforcement, stress concentration factor (Kt), R ratio (R), peak stress (S), temperatures (T), whereas, output of the ANN model consist of number of failure cycles. ANN controller was trained with Levenberg-Marquardt (LM) learning algorithm. The tested actual data and predicted data were simulated by a computer program developed on MATLAB platform. It is shown that the model provides intimate fatigue life estimations compared with actual tested data.Öğe Influence of A Novel Catalysis on The Pyrolysis Yields Obtained by Two Different Reactors(2020) Toklu, Ethem; Polat, Fikret; Kılınçel, MertIn the present study mixtures of polymeric and cellulosic biomass materials were pyrolized in the presence of two different catalysts (sepiolite and aluminium bauxite) in various ratios by two different reactors; a rotary kiln reactor (RKR) and a fixed bed pyrolysis reactor (FBR). The results were compared to determine the effects of pyrol ysis parameters such as catalysts, feedstock and reactor types on the energy content of the final products. First, the polymeric and cellulosic materials were mixed at certain ratios and thus the mixtures were prepared. Then, thermally activated catalysts were added to these mixtures. At the end of the experiments, certain properties such as higher heating value (HHV), the elemental concentrations, particle size and size surface areas of the end products (for solid and liquid phases) were calculated and analysed. The HHV of the liquid products from bauxite added mixture in RKR and FBR was 42.74 MJ/kg and 40.95 MJ/kg respectively. Besides the HHV of the oil products from sepiolite added mixture in RKR and FBR was 41.28 MJ/kg and 38.94 MJ/kg respectively. These values are same and close to HHV of the conventional diesel (42.7 MJ/kg). However no considerable effect seen on HHV of char products from catalyst added mixtures. On the other hand, due to the SEM images the char products it can be clearly concluded that com paring with FBR, RKR had the better performance on pyrolysis of the biomass mixtures.Öğe Investigation of flow and vacuum lifting force on a noncontact end effector for robotic handling of non-rigid material(2011) Toklu, Ethem; Erzincanlı, FehmiThis study identifies the need for a new range of end effectors suitable for non-rigid products and introduces a novel non-contact gripping device. The end effector operates on the principle of generating a high-speed fluid flow between the end effector and product surface thereby creating a vacuum which levitates the product. The lifting forces and conditions are discussed by using optimization methodology and finite element analysis. The experimental results are presented using the end effectors that have been operated to lift non-rigid food materials such as jelly blocks. © 2011 Academic Journals.Öğe Modeling of Radial Flow on a Non-Contact End Effector for Robotic Handling of Non-Rigid Material(Univ Nacional Autonoma Mexico, 2012) Toklu, Ethem; Erzincanlı, FehmiIn this study a numerical model on radial flow and pressure distribution showing regions of negative values which tend to levitate products is developed. The end effector operates on the principle of generating a high-speed fluid flow between the end effector and product surface thereby creating a vacuum which levitates the product. The Navier-Stokes equations and the equation of continuity describing the flow between the nozzle and material are numerically solved by finite volume discretization method. The lifting forces and conditions are discussed by comparing numerical results with experimental findings.Öğe A new mathematical model of peristaltic flow on esophageal bolus transport(2011) Toklu, EthemA new mathematical model is developed for peristaltic transport in the esophagus. Manometric measurements of luminal pressure have been obtained in the esophagus and interpreted both biological and mechanical point of view. Biological data analysis pointed out that pressure distribution has a polynomial form along the esophagus. However, it has been considered as sinusoidal in calculations by scientists. Therefore, a mathematical result does not possibly fit same form with biological data. The developed model is calculated successfully with pressure distribution along the esophagus. The model is applied to a single contraction wave of normal swallowing in the esophagus. Analytical calculation from the new model on pressure distribution is in qualitative agreement with experimental observations. © 2011 Academic Journals.Öğe Overview of potential and utilization of renewable energy sources in Turkey(Pergamon-Elsevier Science Ltd, 2013) Toklu, EthemThe necessity of minimizing environmental impacts of energy use, particularly those with potentially worrisome global effects, is perhaps the greatest challenge resulting from the twentieth century's energy advances. The renewable energy technologies of wind, biofuels, solar thermal and photovoltaics are finally showing maturity and the ultimate promise of cost competitiveness. Turkey's demand for energy and electricity is increasing rapidly and heavily dependent on expensive imported fossil energy resources that place a big burden on the economy and environmental pollution is becoming an important concern in the country. With respect to global environmental issues, Turkey's carbon dioxide emissions have grown along with its energy consumption. States have played a leading role in protecting the environment by reducing emissions of greenhouse gases. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions for clean and sustainable energy development in Turkey. This study shows that there is huge potential for renewable energy in Turkey, especially hydropower, biomass, geothermal, solar and wind. (C) 2012 Elsevier Ltd. All rights reserved.Öğe A research on hydrogen production from industrial waste heat by thermal water splitting(Pergamon-Elsevier Science Ltd, 2016) Toklu, Ethem; Avcı, Arzu Coşkun; Kaygusuz, Kamil; Gür, MahmutEnergy is the most important issues of social and economic life in countries either developed or just developing. It is very well known that hydrogen energy, which is the most advanced energy carrier; environmental friendly and sustainable, can compensate the increasing energy requirements. The generation of hydrogen through electrolysis possessed several advantages, such as high efficiency, low pollutant emissions and flexible fueling strategies. This research aims to create an efficient, effective and multi-disciplinary solution package to produce hydrogen evaluating the waste heat. The main goal of this research was to increase the efficiency of hydrogen production by operating the Solid Oxide Electrolysis Cell (SOEC) at an optimum combination of operating conditions. Number of electrolysis cell, the number of stacks and cell area which are the parameters that affect the high temperature electrolysis are determined on the basis of previous studies. Steam temperature and steam flow rate that are calculated parametrically for the system. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
