Yazar "Kahraman, Ali" seçeneğine göre listele

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    Çok değişkenli optimizasyon ile organik Rankine çevrim verimini etkileyen parametrelerin hassasiyet ve katkı oranlarının tespiti
    (Pamukkale University, 2023) Ata, Sadık; Kahraman, Ali; Şahin, Remzi
    Bu çalışmada, Organik Rankine Çevrimi (ORÇ) üze rinde etkisi olan performans parametrelerinin hassasiyet seviyeleri ve katkı oranları belirlenmiştir. Performans parametreleri evaporatör-kondenser pinch point sıcaklık farkı (Delta T-pp,T-e,Delta T-pp,T-k), soğutma suyu giriş sıcaklığı (T-c,T-l), aşırı kızdırma sıcaklığı (T-ak), türbin-pompa izantropik verimleri(eta(t) ve eta(p)) olarak seçilmiştir. Bu parametrelerin ORÇ sistemi üzerindeki etkisi farklı amaç fonksiyonları altında değerlendirilmiştir. İncelenen amaç fonksiyonları; ısıl verim, net güç ve ekserji verimi maksimizasyonu ile toplam tersinmezlik, hacimsel debi oranı (VFR) ve çevresel etki faktör (EEF) minimizasyonudur. Böylece enerji-ekserji analizi ile termodinamik performans, türbin ekonomisinde önemli etkisi olan VFR ve termodinamik sürdürülebilirlik indeksleri ile çevresel faktör incelenmiştir. Amaç fonksiyonlarının değişmesiyle performans parametrelerinin etkisinin büyük bir oranda değişkenlik gösterdiği tespit edilmiştir. Delta T-pp,T-e’nin etkisi maksimum ısıl verimin elde edilmesinde %20.59 etkili iken, maksimum türbin gücünün elde edilmesinde %71.9 etkili olduğu tespit edilmiştir. Çalışmada Taguchi-ANOVA’dan yararlanılmıştır. L25 ortogonal dizilim kullanılmasıyla amaç fonksiyonlarına ulaşılmasında optimum ortogonal dizilimler ve parametrelerin hassasiyet seviye sıralaması tespit edilmiştir. Tüm amaç fonksiyonlarının eşit oranda etkilediği bir ağırlık fonksiyonu tanımlanmasıyla ORÇ performansı üzerinde %42.85 Delta T-pp,T-e ve %25.71 ise T-c,T-t ’nin etkisinin olduğu belirlenmiştir. Son olarak; regresyon analizi ile her bir amaç fonksiyonu için performans parametrelerine bağlı olarak denklemler çıkarılmıştır. Ampirik denklem ile tahmin edilen sonuçlar ile nümerik analiz sonuçları arasındaki hata oranları çıkartılmıştır. Bu oranlara bakıldığında ampirik denklemlerin ORÇ performansının belirlenmesinde başarılı bir şekilde kullanılabileceği tespit edilmiştir.
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    The Effect on Performance and Exhaust Emissions of Adding Cotton Oil Methyl Ester to Diesel Fuel
    (2016) Kahraman, Ali; Ciniviz, Murat; Örs, İlker; Oğuz, Hidayet
    In the study, engine performance and exhaust emissions of diesel fuel and cotton oil methyl ester (COME) blends at proportions of 2%, %5 and 10% (v/v) have been investigated. The engine was fuelled with COME-diesel blends and pure diesel when running the engine at six different engine speed (1000, 1200, 1400, 1600, 1800, 2000 rpm) and at full load. Test results are presented engine torque and specific fuel consumption (SCF) as engine performance, and Carbon monoxide (CO), Hydrocarbon (HC), smoke and nitrogen oxides (NOx) as exhaust emissions. As result, this study is show that although engine performance decreased with COME adding to diesel fuel, exhaust emissions was generally improved.
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    Effects on Performance, Emission and Combustion Parameters of Addition Biodiesel and Bioethanol into Diesel Fuel
    (2017) Örs, İlker; Kahraman, Ali; Ciniviz, Murat
    In this study, safflower based biodiesel produced in the pilot plant were blended with certainamounts of diesel fuel and bioethanol from sugar beet. Diesel fuel and the blends were testedin a direct injection diesel engine and engine performance, combustion and exhaust emissioncharacteristics were investigated. According to test results, the brake specific fuel consumptionsof biodiesel blend were about 8.51% higher than diesel fuel. Bioethanol is increased brakespecific fuel consumptions values up to 26.77%. The maximum cylinder gas pressure ofbiodiesel blend was about 0.46% higher than that of diesel fuel on average. This value wasdecreased about 1.75% with using of bioethanol. The exhaust emission results showed thatbiodiesel blend decreased carbon dioxide emissions and smoke opacity, while it increasednitrogen oxide emissions and exhaust gas temperature. Nitrogen oxide emissions, smokeopacity and exhaust gas temperature values were decreased with adding bioethanol, while itincreased carbon dioxide emissions.
  • Küçük Resim Yok
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    Energy and Exergy Analyses of a Diesel Engine Fuelled with Biodiesel-Diesel Blends Containing 5% Bioethanol
    (Mdpi, 2016) Kul, Bahar Sayin; Kahraman, Ali
    In this study, energy and exergy analysis were performed for a single cylinder, water-cooled diesel engine using biodiesel, diesel and bioethanol blends. Each experiment was performed at twelve different engine speeds between 1000 and 3000 rev/min at intervals of 200 rev/min for four different fuel blends. The fuel blends, prepared by mixing biodiesel and diesel in different proportions fuel with 5% bioethanol, are identified as D92B3E5 (92% diesel, 3% biodiesel and 5% bioethanol), D85B10E5 (85% diesel, 10% biodiesel and 5% bioethanol), D80B15E5(80% diesel, 15% biodiesel and 5% bioethanol) and D75B20E5 (75% diesel, 20% biodiesel and 5% bioethanol). The effect of blends on energy and exergy analysis was investigated for the different engine speeds and all the results were compared with effect of D100 reference fuel. The maximum thermal efficiencies obtained were 31.42% at 1500 rev/min for D100 and 31.42%, 28.68%, 28.1%, 28% and 27.18% at 1400 rev/min, respectively, for D92B3E5, D85B10E5, D80B15E5, D75B20E5. Maximum exergetic efficiencies were also obtained as 29.38%, 26.8%, 26.33%, 26.15% and 25.38%, respectively, for the abovementioned fuels. As a result of our analyses, it was determined that D100 fuel has a slightly higher thermal and exergetic efficiency than other fuel blends and all the results are quite close to each other.
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    The experimental investigation of diesel fuel-biofuel blends at different injection pressures in a DI diesel engine
    (Academic Publication Council, 2021) Ors, Ilker; Ciniviz, Murat; Kul, Bahar Sayin; Kahraman, Ali
    In this study, it was aimed to investigate the effects of a diesel-biodiesel blend (B20) and a diesel-biodieselbioethanol blend (BE5) on combustion parameters in addition to engine performance and exhaust emissions compared with diesel fuel. Parameters included in the evaluation was brake specific fuel consumption, brake thermal efficiency, CO, CO2, HC, NOx, smoke opacity emissions and finally cylinder pressure, heat release rate, ignition delay, some key points of the combustion phases such as start of ignition, start of combustion, CA50 and CA90 and combustion duration. Engine tests were conducted at different injection pressures of 170 bar, 190 bar, which is the original injection pressure, and 220 bar by the engine being loaded by 25, 50, 75 and 100% for the assessment of engine performance and exhaust emissions. For combustion evaluation, the data obtained at 1400 rpm, maximum torque -speed, and 2800 rpm, maximum power-speed were used, while the injection pressures were set to 170, 190 and 220 bar under full load condition. According to test results, the better performance characteristics, exhaust emissions and combustion behaviour of engine were obtained with the use of BE5 at high injection pressure. So, BE5 fuel improved brake specific fuel consumption by about 7% and brake theunal efficiency by about 6% compared to B20. In addition, while the emission values of BE5 gave better results than diesel fuel, it reduced the NOx and smoke emissions of B20 by approximately 1.4% and 6.4% respectively. Moreover, it has achieved a reduction in smoke emission of up to 45% compared to diesel fuel.
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    An overview of renewable electric power capacity and progress in new technologies in the world
    (Pergamon-Elsevier Science Ltd, 2015) Bilgili, Mehmet; Ozbek, Arif; Sahin, Besir; Kahraman, Ali
    In recent years, the atmosphere has been exposed to a substantial increase in concentration of the trace gases. In 2012, energy-related CO2 emissions reached a record of 31.6 gigatonnes which corresponds to 1.4% comparing to 2011. According to the International Energy Agency (IEA), an energy revolution is needed to achieve a 50% reduction of global CO2 emissions relative to current levels by 2050. In this revolution, energy efficiency, energy storage, new transport technologies, nuclear energy and CO2 capture and storage should play a crucial role. Furthermore, renewable energy technologies comprise a large potential for emission reductions which takes second place after energy efficiency improvements. Until 2035, renewable energy will also have greater impact than other potential alternatives including both CO2 capture and storage or nuclear energy. For this reason, renewable energy industries, markets, and policy frameworks are developed rapidly in recent years, and they will play a substantial role in the world's future. This paper presents an overview of renewable electric power capacity worldwide and discusses the current status, technologies, industry and recent developments of renewable energy sources (RESs) in detail. In addition, the top countries in terms of total installed renewable electric power capacity are also identified. (C) 2015 Elsevier Ltd. All rights reserved.
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    Prediction and sensitivity analysis under different performance indices of R1234ze ORC with Taguchi's multi-objective optimization
    (Elsevier, 2020) Ata, Sadik; Kahraman, Ali; Sahin, Remzi
    In this study, parametric optimization and sensitivity analysis of performance parameters were performed for the Organic Rankine Cycle (ORC) system at 120 degrees C heat source temperature. R1234ze, which is called the new-generation fluid, was used in the ORC design. Performance parameters have been selected considering Energy, Exergy, Economy (Turbine performance) and Environmental (Thermodynamic sustainability indices) factors. Six performance indices used in the orthogonal design with Taguchi-ANOVA. These are; thermal efficiency, turbine power, exergy efficiency, total irreversibility, Volume Flow Ratio (VFR) and Environmental Effect Factor (EEF). Such control factors as Delta T-pp,T-e - Delta T-PP,T-c - T-c,T-i - T-sup - eta t - eta(P) were selected for the statistical analysis. Sensitivity levels were determined under all performance indices for the designed ORC. It has been determined that indices affect control factors differently. According to the results of the parametric optimization, it was determined that the parameter affecting the ORC performance the most was Delta T-pp,T-e. The effect of Delta T-pp,T-e on ORC performance is stated as 39.72%. EES numerical analysis results were compared with the derived predictive equations using different statistical methods with regression method. When these equations obtained for all objective functions are evaluated, the average MAPE, RRMSE and R-2 values were determined as 4.1%, 4.29% and 94.1%, respectively.