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Öğe Advanced exergy analysis of an integrated solid waste fueled cogeneration system based on organic Rankine Cycle for different working fluids(Pergamon-Elsevier Science Ltd, 2022) Ustaoglu, Abid; Torlakli, Hande; Ergun, Alper; Erdogmus, Ertugrul; Akay, Mehmet EminIn this study, the performance evaluation of an ORC-based solid waste-powered cogeneration system was carried out using conventional and advanced exergy analysis methods. Eight different working fluids including dry (isopentane, n-pentane, n-octane, n-heptane), isentropic (R141b, R123), and wet (methanol, water) types were selected for the evaluation. The total capacity of the heat source was determined with the data obtained from the assessment of municipal solid wastes with different calorific values by the characterization method. Energy and exergy analyses were carried out for each component to examine the effect of selected cycle parameters, including evaporator pressure, intermediate pressure, and condenser pressure, and determine the optimum working fluid for the system. The exergy destruction in the components was split into avoidable/unavoidable and endogenous/exogenous parts in the advanced exergy analysis to identify the improvement potentials and the interaction between the components. The thermal and exergy efficiency values reach the highest values of 81.36 % and 40.76 %, respectively. R141b performs as the best working fluid, while the lowest performance is obtained from water. About 121.3 kW of power generation and 918.2 kW of process heat were obtained from the ORC-CHP system using R141b at 1400 kPa evaporator pressure. Conventional exergy analysis states that the evap-orator, process heater, and turbine are the most critical components, accounting for 67.94 %, 19 %, and 4.92 % of the total exergy destruction rate, respectively. The advanced exergy analysis shows that the priority should be on the turbine having the largest share of the avoidable part. The avoidable part, which accounts for 14.5 % of the total exergy destruction, can be reduced by system improvements.Öğe Demiryolu makası imalatında ön isıtma ve presleme işlemlerinin rayın mekanik ve kimyasal özelliklerine etkisi(2023) Akay, Mehmet Emin; Bıngöl, Umut Emre; Rıdvanogulları, AnılBu makalede demiryolu makas üretiminde kullanılan raylara uygulanan 500 °C ön ısıtma ve presleme işleminin malzemelerin mekanik ve kimyasal özelliklerine etkisi incelenmiştir. Kullanılan ray R260 60E1 olup, aynı şarj numarasına sahip monoblok bir raydan numune olarak, 3 eşit ray parçası alınmıştır. Bu ray parçalarının ikisine 500 °C ön ısıtmalı presleme işlemi uygulanırken, diğer ray parçasına ise ön ısıtma ve presleme işlemi uygulanmamıştır. Ray parçalarından alınan test numunelerine çekme testi, % uzama testi, sertlik testi ve kimyasal kompozisyon testi uygulanmıştır. Elde edilen test sonuçları birbiri içerisinde malzeme sınır değerleri dikkate alınarak incelenmiştir. 500 °C ön ısıtmalı presleme işlemi uygulanan raylardan alınan numunelerden elde edilen test sonuçları incelendiğinde, malzemenin mekanik ve kimyasal değerlerinin sınır değerlerinin içinde kaldığı gözlenmiş, sonuçta makas üretiminde bu tür bir ısıl işlem uygulanması, üretimin kolaylaşması açısından yararlı görülmüştür.Öğe Energetic, exergetic, and environmental evaluation of railway transportation by diesel and electric locomotives(Wiley, 2022) Akay, Mehmet Emin; Ustaoglu, AbidIt is critical to reveal the amount of energy and exergy-losses of a system along with environmental issues. This article aims to carry out energy, exergy, and environmental analyses in rail freight trains hauled by diesel and electric locomotives. This study is an important tool for policymakers and energy-planners to gain insight into the performance of the railway-sector, which is an important transportation way in Turkey. It should be a challenge for society and governmental institutions to decrease the losses and to improve the overall performance due to severe energy-problems. The overall energy-efficiency of diesel trains was calculated to be 29.1% as that of exergy-efficiency was 27.2% between 2005 and 2018. In the case of electric-trains, these became 43.4% for 2005-2018. The average overall energy and exergy efficiencies of the railway sector were calculated to be 30.94% and 29.3%, respectively. The results indicate that there is a significant improvement potential in the railway sector. The average carbon emissions of diesel and electric trains are 1.372 kgCO(2)/kWh and 1.346 kgCO(2)/kWh, respectively. The carbon emission of the electric trains per annual useful energy (kg-CO2/kWh) is comparatively high due to the electricity generation methods in the country.Öğe Enhanced exergy analysis of a waste heat powered ejector refrigeration system for different working fluids(Inderscience Enterprises Ltd, 2017) Ustaoglu, Abid; Alptekin, Mustafa; Akay, Mehmet Emin; Selbas, ResatConventional and enhanced exergy analyses of a waste heat powered ejector refrigeration system using exhausted gas from rotary kiln were carried out. Isentropic (R290, R141b and R142b), wet (R134a and R152a) and dry fluids (R600a) were considered in the cycle in terms of avoidable-unavoidable parts of the exergy destruction to decide improvement potentials of the overall system. The results indicate a significant issue; the importance of component can change regarding refrigerant. The ejector comes into view as an important component to improve the overall cycle performance for R134a while the generator shows the best improvement potential for R600a.Öğe Investigation of the effects of hemp seed oil/diesel/cetane improver fuel blends on diesel engine responses(Taylor & Francis Inc, 2024) Baylak, Mustafa Oguz Kaan; Akay, Mehmet EminFour different fuels consisting of D80K5E15, D82.5K5E12.5, D85K5E10 and D100 were examined as to fuel consumption and exhaust emissions in a single cylinder diesel engine. Experiments were examined at 1500 W, 1000 W and 500 W loads, with the highest being 2000 W. Compared with D100 fuel, It has been observed that there was a 15.3% increase in Break Specific Fuel Consumption (BSFC) in the D80K5E15 mixture, a 6% increase in BSFC in the D82.5K5E12.5 mixture and a 2.3% increase in the D85K5E10 mixture. Exhaust emission values obtained from the experiments were examined. Emission values of D100 fuel were compared with the emission values of three other fuels. According to D100 fuel; carbon monoxide (CO) emissions decreased by 16.8% in the D80K5E15 mixture, 26.6% in the D82.5K5E12.5 mixture and 12.2% in the D85K5E10 mixture, Hydrocarbon (HC) emissions decreased by 30.4% in the D80K5E15 mixture, 42.6% in the D82.5K5E12.5 mixture and decreased by 12.2% in the D85K5E10 mixture. It decreased by 26.5%, Carbon Dioxide (CO2) emissions decreased by 2.2% in the D82.5K5E12.5 mixture and by 0.7% in the D85K5E10 mixture. However, compared to D100 fuel; Oxygen (O2) emission increased by 0.4% in the D82.5K5E12.5 mixture and increased by 0.05% in the D85K5E10 mixture, nitrogen oxide (NOX) emission increased by 25.9% in the D80K5E15 mixture, increased by 30.4% in the D82.5K5E12.5 mixture and increased by 0.05% in the D85K5E10 mixture. It increased by 26.9%. When the D100 fuel was compared with the other three fuel blends, the lowest HC and CO emissions were achieved in the D82.5K5E12.5 fuel blend with 26.6% and 42.6%, respectively. In addition, the lowest NOX emissions were obtained with D100 fuel compared to the D100 fuel of the other three fuel mixtures. The lowest CO emission was 0.025%) in D82.5K5E12.5 fuel at 2000 W load, and the lowest HC emission was 3.00 (ppm) in D82.5K5E12.5 fuel at 1000 W load. In this study, when D100 fuel was compared with the other three fuel mixtures, there has been a substantial reduction in CO and HC emissions and a relative reduction in CO2 emissions. Compared to D100 fuel, the desired reduction in CO, HC and CO2 emissions was achieved for the other three fuel mixtures.Öğe Modeling railway line capacity on Karabuk - Zonguldak line(Gazi Univ, 2022) Akay, Mehmet Emin; Aygun, HilmiIn this study, passenger train operation on the single track railway on the Karabuk-Zonguldak track was examined. A solution was sought for the problems related to waiting and delays on this railway line and the optimum tariff was tried to be found. In the study, daily train capacity that can be operated on the Karabuk-Zonguldak line, where 10-station and 8 daily passenger trains with both directions are operating, was examined and a particle swarm optimization (PSO) based programming model was applied. In this model, the track of 116.6 km between Karabuk and Zonguldak is considered. The simulation study of the proposed method was carried out with the MATLAB program. As a result of the modeling, according to the data provided, the train departure times were rearranged and it was demonstrated with the simulation that 65% improvement was achieved in delays.Öğe Optimisation of machining parameters of train wheel for shrink-fit application by considering surface roughness and chip morphology parameters(Elsevier - Division Reed Elsevier India Pvt Ltd, 2020) Akay, Mehmet Emin; Ridvanogullari, AnilThe train wheel is one of the elements most exposed to static and dynamic loads during the transport. For this reason, it is of great importance for the safety of rail transportation that the wheel-axle assembly is carried out securely through the shrink-fit method. The surface roughness of the inner diameter of the wheel must be within 0.8-3.2 mu m in order to provide the optimum shrink-fit. In this study, different depth-of-cut, feed rate and cutting speed parameters were considered in the turning process of ER8 class train wheel, and optimum machinability parameters were determined. In the experimental study, the Taguchi experimental design method, regression analysis and variance analysis (ANOVA) method were used. Experimental results were examined visually by using chip photographs and SEM images. According to the ANOVA results, it was determined that the most effective parameter is the feed rate with 93.78% on surface roughness in the turning of the train wheel. The SEM images derived from chips proved that the feed rate has strong correlation with surface roughness. Optimum machining parameters were determined as 1.5 mm depth of cut, 0.1 mm/rev feed rate and 250 rpm cutting speed. (c) 2020 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Öğe Thermal and exergetic approach to wet type rotary kiln process and evaluation of waste heat powered ORC (Organic Rankine Cycle)(Pergamon-Elsevier Science Ltd, 2017) Ustaoglu, Abid; Alptekin, Mustafa; Akay, Mehmet EminIn this study, the energetic and exergetic performance analysis of a rotary kiln and cooling section in a cement factory using wet method was carried out based on the actual operational data. The energy and exergy efficiencies of the wet type rotary kiln are about 46% and 35%, respectively. The results showed that a great amount of heat energy of 30.5 MW is exhausted from the chimney of rotary kiln. In order to evaluate recovery capacity of exhausted gas, Organic Rankine Cycle (ORC) was considered and its energetic and exergetic performance were evaluated for isentropic and dry type fluids for different conditions. Isentropic fluid, R245fa shows the best performance while the dry fluid, R600a has the lowest performance. For condensation temperature of 303 K and evaporation pressure of 1500 kPa, the thermal and exergy efficiencies of R600a are 9.8% and 21.7% while the thermal and exergy efficiencies of R245fa are 13% and 29%, respectively. Isentropic fluids, R245fa, R142b can be used at high evaporator pressures and low condenser temperatures as R600 and R600a are not appropriate after a certain pressure since the efficiency remain stable. The exergy destruction rates in heat exchanger and evaporator are about 80% of the total exergy destruction. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Türkiye’de dizelli tren işletmeciliğinde enerji verimliliği ve emisyonların araştırılması(2023) Akay, Mehmet Emin; Çelik, VeliBu çalışmada Türkiye'de dizelli lokomotiflerle yapılan yük ve yolcu taşımacılığı kaynaklı enerji verimliliği ve yıllık emisyon miktarları hesaplanmıştır. Verimlilikte ana kriter hamton.km olarak alınmış, 2013-2017 yıllarını kapsayan 5 yıllık dönem için 1 hamton.km seyir için harcanan yakıt ve 1 litre yakıt ile gidilen hamton.km değerleri hesaplanmıştır. Dönem sonuna göre, 1 hamton.km seyir için harcanan yakıt miktarının azaldığı ve 1 litre yakıt ile gidilen hamton.km değerinin arttığı görülmüştür. HC, CO, NOx ve PM10 kirleticilerinden oluşan emisyon toplamının 2014 yılında zirve yaptığı, sonraki yıllarda azaldığı gözlenmiştir. CO ve NOx emisyonları en yüksek miktar olmuştur. Çözümler olarak; elektrikli loko kullanımının arttırılması, maden cevheri vb. ağır tonajlı taşıma yapılan işletme bölgelerinde taşımaların E lokolarla yapılması, enerji giderinin ve emisyonların azaltılmasında TSİ sisteminin yaygınlaşması ile, yoğun yük taşımacılığı yapılan bölgelerde çift hat yapımına öncelik verilmesi önerileri yapılmıştır.Öğe Türkiye’de tam otomatik sürücüsüz anahat treni çalıştırılmasında olası fırsatlar ve tehditler(2024) Ekıcı, Üsame; Akay, Mehmet EminÇeşitli teknolojik gelişmeler yaşandıkça insan gücüne daha az ihtiyaç duyulacağı aşikardır. Bu bağlamda, sürücüsüz trenler demiryolu endüstrisindeki son başarı olarak görülmektedir. Sürücüsüz trenler insan hatalarından kaynaklanan kazaların önlenmesinde, seferlerin dakikliği ve sıklığını artırmada, enerji tüketiminin ve insan işgücü maliyetinin azaltılmasında önemli rol oynamaktadır. Öte yandan işçi sendikalarının neredeyse tamamı, demiryolu işçilerinin işlerinden uzak tutulmasına ve otomasyona geçilmesine karşı çıkmaktadırlar. Ayrıca demiryolu hattı yakınındaki potansiyel tehlikeler iyi eğitimli sürücüler tarafından görülebilmekte fakat bazen engel algılama özelliğine sahip olmasına rağmen bilgisayarlar tarafından tespit edilememektedir. Ayrıca tam otomatik sistemler siber saldırılara karşı savunmasızdır ve çok iyi korunması gerekmektedir. Bununla birlikte psikolojik araştırmalar, yolcuların trende herhangi bir görevli göremedikleri zaman kaygılandıklarını ve bu durumun insanların yolculuklarının konfor seviyesini düşürdüğünü göstermektedir. Bu çalışmada, ana hat trenlerinin sürücüsüz çalıştırılmasının avantaj ve dezavantajları ayrıntılı olarak verilmekte olup mevcut sürücüsüz metro trenlerinin daha derinlemesine izlenip analiz edilerek deneyim kazanılması konusunda önerilerde bulunulmaktadır.
