Oxy-Fuel Combustion

The integration of CNG and green hydrogen as supplementary fuels in diesel engines presents a significant opportunity to enhance the sustainability of power generation, particularly in electric generator power plants. This study investigates the dual-fuel operation of diesel engines using a blend of CNG and green hydrogen, focusing on the performance metrics and environmental impacts. Quantitative findings show that replacing up to 40% of diesel with CNG and hydrogen leads to a 30% reduction in CO2 emissions, a 25% reduction in particulate matter (PM) emissions, and up to a 15% decrease in nitrogen oxides (NOx) compared to diesel-only engines. Additionally, hydrogen's zero-carbon combustion contributes to a 40% reduction in overall greenhouse gas (GHG) emissions, when the hydrogen is produced through renewable electrolysis. Efficiency improvements of up to 10% were recorded, largely due to hydrogen's high flame speed, which enables faster and more complete combustion. Despite challenges such as hydrogen storage, distribution infrastructure, and engine modifications, the dual-fuel approach retains the operational flexibility of conventional diesel generators while offering significant environmental advantages. Power plant adopting this approach is the Karaganda power plant in Kazakhstan, where a CNGhydrogen-diesel blend has been tested in diesel generator units. This pilot project reported a 20% improvement in fuel efficiency and a 35% reduction in carbon emissions, proving the commercial viability of this technology in industrial-scale power generation. Furthermore, in regions like Germany, where green hydrogen production is becoming more widespread, similar applications are emerging as part of broader strategies to decarbonize energy systems.

Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.

Global warming has made mankind's need for clean energy more vital. Hydrogen has been the focus of researchers as a clean fuel in recent decades, and recently, extensive studies have been conducted to find suitable solutions for maximizing the efficiency of this fuel. Salt caverns formed by the dissolution of salt domes are recognized as one of the most important geological structures for medium-term and secure hydrogen storage. The presence of various impurities poses challenges to the storage operations, with carbon dioxide being a potential impurity. In this study, the effect of temperature on various parameters, including changes in salt cavern pressure, partial pressures of components, hydrogen quality, saturation, and hydrogen molar quantity, was investigated using a computational fluid dynamics approach. The results indicated that the partial pressures of hydrogen and carbon dioxide decrease over time under any condition, while the partial pressure of methane increases, ultimately leading to a decrease in overall cavern pressure. Methane produced at the interface between hydrogen and carbon dioxide reduces the rate of hydrogen consumption reaction and produces impurities, acting like a cushion gas. Generally, caverns with higher temperatures result in up to a 16% decrease in hydrogen quality due to increased reaction rates and mixing levels, making caverns with lower temperatures more desirable.

پیش بینی الگوي جریان باد در اطراف ساختمانهاي بلند،به دلیل مطرح شدن مسائلی چون توزیع وانتشار آلاینده
ها،مسائل زیست محیطی و حتی طراحی سازه اي آن،امروزه جایگاه ویژه اي پیدا کردهاست.جریان آشفته ي هوادر اطراف
ساختمان ها،به دلیل پیچیدگیهاي فیزیکی ازجمله وجود گوشه هاي تیز،اثر زمین و وجود گردابه ها،یکی از بهترین گزینه
ها براي ارزیابی دقت و کارآیی مدلهاي آشفتگی می باشد.در شرایط کنونی پدیده ي ریزگردها به عنوان یک موضوع تاثیرگذار
در زندگی و سلامت انسان ها جلب توجه نموده وسبب آلودگی هواي شهرها شده و خسارات فراوانی را به محیط زیست و
ساختمان ها وارد می کند.دراین پژوهش،مدل سازي عددي میدان جریان و بررسی اثر چیدمان و تغییرات غلظت آلاینده ها
بامقایسه ي مدل هاي 2 و 4 ساختمان و بررسی اثرات انتشار ذرات جامد ریزمقیاس در اطراف ساختمان ها با ارتفاع هاي
مختلف در محیط هاي شهري با بهره گیري از روش شبیه سازي عددي انجام شده است.جنس ذرات آلاینده از نوع غالب آن
در محیط هاي شهري)ذرات خاک رس (می باشد.به منظور بررسی جریان اطراف ساختمان ها از روش شبیه سازي عددي
میدان جریان آشفته اطراف آنها با استفاده از روش URANS )متوسط گیري شده رینولدز ناپایا(و بررسی توزیع،انتشارو
تجمع آلاینده هاي هوا)ذرات گردوغبار(با استفاده از مدل فاز جداگانه انجام گرفته است.نتایج حاصل ازاین پژوهش براي شدت
اثرات آلودگی هواو ایجاد جریانهاي آشفته در قسمتهاي مختلف ساختمانها،تأثیر پارامترهاي جریان و طراحی ساختاري
بر شدت انتشار و غلظت آلایندهها به منظور کاهش اثرات سوء زیست محیطی ارائه شدهاست.همچنین به دلیل حبس ذرات
آلاینده و تغییر ناگهانی ارتفاع ساختمانهاوتشکیل گردابه ها وایجادآشفتگی بیشتر،مجموع ذره هاي ریزگرد قرار گرفته در
این حجم و در بازه ي زمانی بلند مدت افزایش یافته و تحلیل نتایج و مقایسه ي نمودارها نشانداد که بیشتر تجمع ورسوب
ذرات آلاینده درگوشههاي ساختمان ها و نیز متاثر از جهت وزش باد است.

This paper presents a summary of technical-economic studies. It allows evaluating, in the French context, the production cost of electricity derived from coal and gas power plants with the capture of CO 2 , and the cost per ton of CO 2 avoided. Three systems were studied: an Integrated Gasification Combined Cycle (IGCC), a conventional combustion of Pulverized Coal (PC) and a Natural Gas Combined Cycle (NGCC). Three main methods were envisaged for the capture of CO 2 : pre-combustion, post-combustion and oxy-combustion. For the IGCC, two gasification types have been studied: a current technology based on gasification of dry coal at 27 bars (Shell or GE/Texaco radiant type) integrated into a classical combined cycle providing 320 MWe, and a future technology (planned for about 2015-2020) based on gasification of a coal -water mixture (slurry) that can be compressed to 64 bars (GE/Texaco slurry type) integrated into an advanced combined cycle (type H with steam cooling of the combustion turbine blades) producing a gross power output of 1200 MWe.

The main methods of reducing nitrogen oxides concentration in flue gases during the boiler plants operation are considered and analyzed. It was shown that simplified recirculation scheme with the flue gases supply into the inlet of the blower fan makes it possible to reduce emissions of nitrogen oxides at relatively low capital and operating costs. The aim of the work is to evaluate the impact of flue gases recirculation into the furnace on the technical, economic and ecological characteristics of the ship's auxiliary boiler. The research was carried out using the methods of computer simulation. A new data of the flue gases recirculation effect on the main characteristics of the ship auxiliary boiler Aalborg OM-TCi with a steam capacity of 20,0 t/h were obtained. It was found that the recirculation of flue gases in the range of 0 … 20 % leads to a decrease in the adiabatic temperature in the furnace by 273°C (from 1919 to 1646°C), the average integral temperature in the active combustion zone decrease from 1773 to 1534°C, and the temperature of gases at the outlet of the furnace decrease from 1300 to 1233°C. The boiler flue gas temperature rises from 225 to 236°C. An increase in heat losses with flue gases by 0,5% leads to a decrease of the boiler efficiency from 89,2 to 88,7%. The furnace heat absorption decreases by 999 kW and the heat absorption of convective steam-generating tube bundle increases by 900 kW. The decrease in the boiler steam output is 0,11 t/h. The recirculation coefficient in the range of 10 … 15% is recommended to choose on the basis of the study results. The given values of the recirculation coefficient correspond to an increase in the resistance of the gas-air path of the boiler by 25%, as well as a decrease in nitrogen oxide emissions by 44%.

In this study, pollutant gas emissions and combustion efficiency of LPG fuel burning in a steam boiler were investigated experimentally and compared with the diesel fuel-based results. Designed and manufactured of a new tangential swirl burner, and used for gaseous fuel combustion (LPG) in the boiler that was already designed to be operated with liquid fuel (diesel). The study involves conducting experiments using a broad range of equivalence ratios (Φ) and with three different diameter ratios (dr = 1/10, 1/15, and 1/20) (diameter ratios = The variable diameter of the burner is compared against the fixed diameter of the boiler). The volumetric ratios of CO 2 , CO as well as the HC content in the exhausted gases are measured and the boiler efficiency is predicted. The obtained results revealed that the replacement of the liquid fuel burner with the tangential swirl gas (LPG) burner is simple, inexpensive, and had no negative effect on the other parts of the boiler. In addition, the lowest pollutant gas concentrations detected in the exhausted gases and the highest boiler efficiency are obtained with a diameter ratio of 1/10. In comparison with diesel fuel combustion, the LPG fuel offered the cleanest combustion at Φ approaching 1 and above, required less O 2 for complete combustion, and had the least HC content in the exhaust gases at the lean mixing area. Finally, the boiler efficiency operating with LPG fuel was higher than that obtained with diesel fuel for all equivalence ratios.

In the evolving landscape of global energy systems, optimizing subsurface fossil fuel extraction while transitioning toward low-carbon paradigms has become a strategic imperative. This paper investigates how artificial intelligence, enhanced recovery methods, and carbon management technologies converge to improve efficiency and reduce emissions in oil, gas, and coal sectors. Emphasis is placed on real-time reservoir modeling, CO₂ capture integration, and hybrid offshore systems using renewable energy. Drawing from original research, the study highlights multi-scale innovations that allow fossil fuels to serve as transitional energy sources with minimized environmental footprint.

Pembakar Siklon adalah tungku berbentuk silinder, dimana serbuk bahan bakar ditiupkan bersama udara pembakar secara tangensial, sehingga serbuk bahan bakar akan berputar dan terbakar dalam ruang siklon tersebut secara intensif. Tingkat homogenitas bahan bakar dengan udara (reaktan), waktu tinggal reaktan, tingkat turbulensi serta energi kinetik turbulensi (TKE) sangat mempengaruhi efisiensi pembakaran. Untuk mengetahui gambaran lebih detail terhadap fenomena turbulensi dan nilai TKE pada pembakar siklon maka dilakukan kajian secara numerik dengan simulasi Computational Fluid Dynamics (CFD). V ariasi kecepatan udara awal yang d igunakan dalam si mulasi ad alah 9,35; 8,45;7,52 m/s. Domain utama untuk simulasi adalah tungku pembakar siklon yang mempunyai panjang 148 cm dengan diameter outlet 42 cm dan diameter pada pangkal interiornya 22 cm. Kecepatan udara awal untuk memvalidasi hasil simulasi diukur menggunakan venturi meter dan kecepatan aliran udara didalam tungku pembakar siklon d...

Bu araştırmada, ülkemizde yakıt olarak imalatı ve satışı yapılan odun peletlerinin kalite özellikleri belirlenmiş ve katı biyo-yakıtların yakıt özelliklerine yönelik farklı standartlara (DIN51731, DIN Plus, ÖNORM 7135, ISO 17225-2) uygunluğu araştırılmıştır. Ayrıca, bu peletler için baca gazı analizleri de gerçekleştirilmiştir. Elde edilen emisyon sonuçları, Avrupa Birliği 2015/1185 ve 2015/1189 yönetmelikleri, TS EN 303-5 standardı, Sanayi Kaynaklı Hava Kirliliğinin Kontrolü Yönetmeliği (SKHKKY)" ve "Isınmadan Kaynaklanan Hava Kirliliğinin Kontrolü Yönetmeliği" (IKHKKY) tarafından belirlenen emisyon sınırları ile karşılaştırılmıştır. Bu amaçla, Türkiye'de 5 farklı şehirden odun peleti imalatı ve satışı yapan 10 farklı firmadan örnekler toplanmış ve alınan örneklerin standartlarda limit değerleri belirtilen özelliklerden olan uzunluk, çap, yoğunluk, mekanik dayanıklılık, nem içeriği, kül içeriği, ısıl değer ve baca gazı emisyon değerleri saptanmıştır. Ölçüm sonuçlarına göre, pelet örneklerinde uzunluk değeri 15.69-30.82 mm, çap değeri 6.06-10.39 mm, pelet yoğunluk değeri 944.91-1148.23 kg/m 3 , yığın yoğunluk değeri 482.8-641.8 kg/m 3 , mekanik dayanıklılık değeri %95.11-99.22, nem içerikleri %4.32-5.72, kül içerikleri %1.03-2.16, ısıl değerleri 18.08-18.49 MJ/kg arasında saptanmıştır. Baca gazı emisyon değerlerinden O2 içeriği %12.7-71.7, CO miktarı 1443-2127 ppm, NOx miktarı ise 83.7-213.0 ppm arasında ölçülmüştür. Ülkemizde de geçerli olan ISO 17225-2 standardında belirtilen kalite özelliklerine ilişkin sınır değerler açısından da pelet örneklerinde uzunluk, nem içeriği, ısıl değer açısından örneklerin %100'ünün uygun; çap, yığın yoğunluğu açısından da örneklerin %80' inin standartlara uygun olduğu belirlenmiştir. Öte yandan kül içerikleri incelendiğinde, örnekler içinde ENplusA1 sınıfına uygun pelet örneği olmadığı, %40' ının ENplusA2 sınıfına ve %80'inin ise ENplusB sınıfına girdiği, %20'sinin standart dışı olduğu saptanmıştır. Pelet örneklerinin CO emisyon değerleri AB yönetmeliklerinde belirlenen emisyon sınır değerini aşmıştır dolayısıyla AB Ekodesigndirektifinde belirtilen hiçbir ısıtma sisteminde bu çalışma kapsamında incelenen örneklerin uygun olmadığı belirlenmiştir. Aynı şekilde IKHKKY ve SKHKKY'de belirlenen emisyon limitleri incelendiğinde de bu yönetmeliklerde belirtilen yakma sistemlerinde pelet örneklerinin CO emisyonu açısından uygun olmadığı belirlenmiştir. TS EN 303-5 standardında belirtilen CO emisyon değerlerine göre incelediğimiz tüm pelet örneklerinin sadece "Sınıf 3"'e 50 kW ısıl güç değerine kadar tüm ısıtma sistemlerinde kullanılabileceği, peletlerin %80'inin 50kW-150 kW ısıl güce sahip sistemlerde kullanılabileceği fakat daha yüksek ısıl güce sahip sistemler için hiçbirinin kullanımının uygun olmadığı saptanmıştır.

Bu araştırmada, ülkemizde yakıt olarak imalatı ve satışı yapılan odun peletlerinin kalite özellikleri belirlenmiş ve katı biyo-yakıtların yakıt özelliklerine yönelik farklı standartlara (DIN51731, DIN Plus, ÖNORM 7135, ISO 17225-2) uygunluğu araştırılmıştır. Ayrıca, bu peletler için baca gazı analizleri de gerçekleştirilmiştir. Elde edilen emisyon sonuçları, Avrupa Birliği 2015/1185 ve 2015/1189 yönetmelikleri, TS EN 303-5 standardı, Sanayi Kaynaklı Hava Kirliliğinin Kontrolü Yönetmeliği (SKHKKY)" ve "Isınmadan Kaynaklanan Hava Kirliliğinin Kontrolü Yönetmeliği" (IKHKKY) tarafından belirlenen emisyon sınırları ile karşılaştırılmıştır. Bu amaçla, Türkiye'de 5 farklı şehirden odun peleti imalatı ve satışı yapan 10 farklı firmadan örnekler toplanmış ve alınan örneklerin standartlarda limit değerleri belirtilen özelliklerden olan uzunluk, çap, yoğunluk, mekanik dayanıklılık, nem içeriği, kül içeriği, ısıl değer ve baca gazı emisyon değerleri saptanmıştır. Ölçüm sonuçlarına göre, pelet örneklerinde uzunluk değeri 15.69-30.82 mm, çap değeri 6.06-10.39 mm, pelet yoğunluk değeri 944.91-1148.23 kg/m 3 , yığın yoğunluk değeri 482.8-641.8 kg/m 3 , mekanik dayanıklılık değeri %95.11-99.22, nem içerikleri %4.32-5.72, kül içerikleri %1.03-2.16, ısıl değerleri 18.08-18.49 MJ/kg arasında saptanmıştır. Baca gazı emisyon değerlerinden O2 içeriği %12.7-71.7, CO miktarı 1443-2127 ppm, NOx miktarı ise 83.7-213.0 ppm arasında ölçülmüştür. Ülkemizde de geçerli olan ISO 17225-2 standardında belirtilen kalite özelliklerine ilişkin sınır değerler açısından da pelet örneklerinde uzunluk, nem içeriği, ısıl değer açısından örneklerin %100'ünün uygun; çap, yığın yoğunluğu açısından da örneklerin %80' inin standartlara uygun olduğu belirlenmiştir. Öte yandan kül içerikleri incelendiğinde, örnekler içinde ENplusA1 sınıfına uygun pelet örneği olmadığı, %40' ının ENplusA2 sınıfına ve %80'inin ise ENplusB sınıfına girdiği, %20'sinin standart dışı olduğu saptanmıştır. Pelet örneklerinin CO emisyon değerleri AB yönetmeliklerinde belirlenen emisyon sınır değerini aşmıştır dolayısıyla AB Ekodesigndirektifinde belirtilen hiçbir ısıtma sisteminde bu çalışma kapsamında incelenen örneklerin uygun olmadığı belirlenmiştir. Aynı şekilde IKHKKY ve SKHKKY'de belirlenen emisyon limitleri incelendiğinde de bu yönetmeliklerde belirtilen yakma sistemlerinde pelet örneklerinin CO emisyonu açısından uygun olmadığı belirlenmiştir. TS EN 303-5 standardında belirtilen CO emisyon değerlerine göre incelediğimiz tüm pelet örneklerinin sadece "Sınıf 3"'e 50 kW ısıl güç değerine kadar tüm ısıtma sistemlerinde kullanılabileceği, peletlerin %80'inin 50kW-150 kW ısıl güce sahip sistemlerde kullanılabileceği fakat daha yüksek ısıl güce sahip sistemler için hiçbirinin kullanımının uygun olmadığı saptanmıştır.

Chemical absorption using amineebased solvents have proven to be the most studied, as well as the most reliable and efficient technology for capturing carbon dioxide (CO 2 ) from exhaust gas streams and synthesis gas in all combustion and industrial processes. The application of single amineebased solvents especially the very reactive monoethanolamine (MEA) is associated with a parasitic energy demand for solvent regeneration. Since regeneration energy accounts for up to threeequarters of the plant operating cost, efforts in its reduction have prompted the idea of using blended amine solvents. This review paper highlights the success achieved in blending amine solvents and the recent and future technologies aimed at increasing the overall volumetric mass transfer coefficient, absorption rate, cyclic capacity and greatly minimizing both degradation and the energy for solvent regeneration. The importance of amine biodegradability (BOD) and low ecotoxicity as well as low amine volatility is also highlighted. Costs and energy penalty indices that influences the capital and operating costs of CO 2 capture process was also highlighted. A new experimental method for simultaneously estimating amine cost, degradation rate, regeneration energy and reclaiming energy is also proposed in this review paper.

In this article, turbulent-gas two-phase in a fluidized bed is investigated and solved. In order to study the above effect, a reactor with different shapes and geometries has been considered and the effect of reactor shapes on the expansion volume of the solid bed has been investigated. The fluidized bed reactor is a types of reactors that can be used to perform multiphase chemical reactions, as well as in the field of producing gasoline and other fuels, many polymers such as rubber, vinyl chloride, polyethylene and styrene, nuclear energy units, burning coal, water purification units, The catalytic cracking process is also used as a dryer. In the inclined fluidized bed, the fluid velocity increases, which increases the product recovery and removes the dried product from the bed. The velocity of phases and particles inside the bed also increases and shows changes in the velocity profile of the solid. Increasing the column diameter decreases the axial solids velocity and smaller particle sizes have more discharge. Increasing the height of the bed reduces the static pressure and increases the frictional pressure. For this purpose, computational fluid dynamics is considered as a useful tool and the most likely method for correct prediction and optimization. In the present research, due to the expensiveness of the experimental method and the lack of equipment, numerical solutions were used.

Dalam industri manufaktur dan pulp, teknologi perpindahan panas memainkan peran penting dalam meningkatkan efisiensi energi dan keberlanjutan proses produksi. Heat exchanger, seperti tipe shell and tube serta plate-frame, telah terbukti efektif dalam mentransfer panas antar fluida, yang berkontribusi pada penghematan energi dan pengurangan emisi gas rumah kaca. Selain itu, pemanfaatan energi terbarukan, seperti gasifikasi black liquor dan sludge, menawarkan solusi alternatif untuk mengurangi ketergantungan pada bahan bakar fosil.

Bu çalışma kapsamında, Trakya Bölgesi'nde yoğun olarak yetiştirilen çeltik bitkisinin hasattan sonra tarlada kalan saplarının gazlaştırılarak enerji içeriklerinin değerlendirilmesi için laboratuvar tipi bir gazlaştırıcı tasarlanmış ve imalatı yapılmıştır. Bölgeden toplanan çeltik sapları %100 sap ve %15 oranında kömür tozu ile karıştırılmış şekilde peletlenmiş ve peletlerin analizleri yapılmıştır. Gerek hammadde ve gerekse pelet örnekleri için gazlaştırma denemeleri gerçekleştirilmiş ve elde edilen gaz örneklerinin içerikleri belirlenmiştir. Gazlaştırma denemeleri sonucunda, kömür katkısının çeltik sapı peletleri için sentez gaz ısıl değerini arttırdığı (3,686 MJ/Nm 3 değerinden 3,71 MJ/Nm 3 değerine) ancak özgül gazlaşma hızının da artmasıyla beraber verime etkisinin olumsuz olduğu gözlemlenmiştir (katkısız peletlerde maksimum %61,9, kömür katkılı peletlerde en fazla %57,41). Çeltik sapı peletlerinin içerdiği yüksek silisyum sebebiyle 800C ve yukarı sıcaklık değerlerinde camla...

This study evaluates the capacity of a series of activated carbons obtained from leather industry waste to retain mercury. The behaviour of these materials was compared in two simulated flue gas compositions at laboratory scale. The atmospheres were i) a typical coal oxy-fuel combustion atmosphere and ii) an O 2 +N 2 atmosphere. The activated carbons displayed different behaviours depending on their characteristics and the gas composition. The best results were obtained for the activated carbon with the highest surface area and greatest amount of micropores, sulphur and acidity character, these results being comparable to those of an activated carbon impregnated with sulfur specifically designed for capturing elemental mercury. The highest level of mercury retention was achieved in a O 2 +N 2 atmosphere. However, independently of the ability of these materials to capture mercury, their most interesting characteristic was their ability to oxidize mercury in an oxy-combustion atmosphere, since this would facilitate the retention of mercury in flue gas desulfurization units with the consequence that the risk of damage to the CO 2 compression and purification units would be reduced or even removed.

Cette brochure présente une comparaison de l'enseignement des fonctions en France et en Italie, dans le secondaire. Dans la première partie, nous présentons le contexte général de l'enseignement primaire, secondaire et supérieur dans les deux pays. Dans la deuxième partie, nous étudions plus particulièrement l'enseignement des fonctions au travers des programmes, dans la filière scientifique au lycée (voire au collège pour la France). Les contenus des deux pays sont analysés en parallèle. Et enfin, dans une troisième partie, nous nous centrons sur la comparaison du sujet de baccalauréat 2013 et celui de la maturità 2013 (examen de fin de lycée en Italie), pour pouvoir cerner les attendus en fin de lycée autour des fonctions dans les deux pays. Nous utilisons une analyse de tâches mettant en jeu les mises en fonctionnement attendues des connaissances du programme. Ce travail présente quelques aspects des points communs et des différences que l'on peut identifier dans l'enseignement sur les fonctions entre les deux pays.

Cette brochure presente une comparaison de l'enseignement des fonctions en France et en Italie, dans le secondaire. Dans la premiere partie, les auteurs presentent le contexte general de l'enseignement primaire, secondaire et superieur dans les deux pays. Dans la deuxieme partie, ils etudient plus particulierement l'enseignement des fonctions au travers des programmes, dans la filiere scientifique au lycee (voire au college pour la France). Les contenus des deux pays sont analyses en parallele. Et enfin, dans une troisieme partie, ils se centrent sur la comparaison du sujet de baccalaureat 2013 et celui de la maturita 2013 (examen de fin de lycee en Italie), pour pouvoir cerner les attendus en fin de lycee autour des fonctions dans les deux pays. Ils utilisent une analyse de tâches mettant en jeu les mises en fonctionnement attendues des connaissances du programme. Ce travail presente quelques aspects des points communs et des differences que l'on peut identifier dan...

Nowadays hydrogen is gaining more and more attention by Industry, Academia and Politics. Being a carbon free fuel, it is supposed to have a key role in the future energy scenario, especially if produced by renewable sources. The use of mixtures of hydrogen and conventional hydrocarbons in gas turbines is one of the most promising technical solutions for obtaining a sustainable combustion during the transition toward a full decarbonization. For this reason, it is fundamental to investigate the behaviour of fuels enriched with hydrogen in combustion processes. In this work, a lab-scale swirled premixed burner has been investigated by means of a fully 3D URANS approach. Firstly, a numerical simulation with cold flow has been performed to validate the model against experimental data. Then, reactive flow simulations have been performed. Initially, a combustion with 100% methane was considered. Then, a 30% by volume hydrogen blending has been investigated. The partially premixed combustio...

The increasing use of compact heat exchangers, which are both lighter and occupy less space than larger exchangers, has made the study of such exchangers more essential. The main aim of this article is to examine several proposed models of this type of converter, incorporating vortex generators with different geometries, in terms of heat transfer rate and pressure drop. To achieve these objectives, vortex generators with sinusoidal wave profiles have been designed and analyzed under various angles of attack and different lengths to determine the effects of these geometric parameters on the heat transfer rate from the tubes and the pressure drop along the converter. In this study, hot air at a constant temperature of 350 K flows inside the tubes, while cold air at a temperature of 300 K flows through the shell of the heat exchanger. The problem has been discretized in a steady-state 2D form for slow fluid flow (Reynolds numbers ranging from 400 to 1000) using the finite element method (FEM) and analyzed with ANSYS Fluent commercial software. The results indicate that sinusoidal vortex generators with an angle of attack of 20 degrees and a length of 6 mm provide the most favorable balance between heat transfer and pressure drop among the studied configurations.

This paper presents a computational fluid dynamics (CFD) analysis of nitrogen monoxide (NO) and nitrogen dioxide (NO2) formation in a biodiesel turbulent non-premixed flame via Eulerian-Lagrangian concept. The model includes governing conservation equation of mass, momentum and energy, and equations representing the tabulation and transport of NOX (NO+NO2). Discrete Ordinates (DO) was exploited for modeling of heat radiation that increases the accuracy of the computational simulation in prediction of NO. The temperatures, and concentration of NOX are presented and compared with experimentation. The proposed model is able to accurately predict the formation of NOX under many circumstances. However, some discrepancies between the model and experimental data exist because of the surrogate combustion mechanism employed for biodiesel fuel and absence of prompt NO in the combustion mechanism employed in CFD codes.

Oxy-fuel combustion is the most promising carbon capture and storage technology, which eliminates carbon dioxide emissions into the atmosphere and also decreases nitrogen oxides emissions thereby lowering global warming potential. In order to implement oxy-fuel combustion technology in full scale power plants, its costs, mainly connected with the amount of pure oxygen produced, must be lowered. The main hypothesis is that it is possible to maintain similar velocity and heat transfer distribution while maintaining stable and efficient burner operation during both combustion technologies modifying burner aerodynamics. Excess oxygen is chosen as a representative parameter of burner's performance and investigation is carried out for four different oxy-fuel burner oxygen excess ratios (λ: 0.8, 0.98, 1.07, and 1.24) together with reference air combustion case. This study suggests a workflow, based on semi-industrial experimental investigations and computational fluid dynamics model composed of advanced sub-models for different combustion phases for development of real scale dualmode coal swirl burners able for efficient operation during both combustion regimes. The results show that the temperature in near-burner zone and nitrogen oxides emissions increase, while carbon monoxide emissions decrease with the increase of burner oxygen excess ratio, and stable combustion with similar velocity and temperature distributions for both combustion modes is achieved for oxygen excess ratio of 1.07, with decrease in nitrogen oxides and carbon monoxide emissions during oxy-fuel combustion. The performed study demonstrates that it is possible to choose the appropriate burner settings regarding nitrogen oxides and carbon monoxide emissions and burner's ability to operate stably in both air and oxy-fuel combustion modes.

In this study, a concentric tube heat exchanger with coiled wire turbulators were analysised numerically by RNG k-ε Turbulent Model in order to be reduced heat exchanger sizes, increased heat transfer enhancement and to be obtained friction characteristics. The analyses were done in a range of Reynolds (Re) number from 3000 to 18000. The numerical simulations were done by using a CFD code namely ANSYS fluent, using finite volume method. Three main turbulence models of RNG k-ε were employed in the simulations such as Model ➀ (RNG-Standard wall function), Model ➁ (RNG-Non-Equilibrium wall function) and Model ➂ (RNG-Enhanced wall treatment). Therefore, the numerical analyses carried out to compare with the experimental results in order to determine the best fitting model using each three main turbulence model of RNG k-ε model, Model ➀ has given the best result. Araştırma makalesi Başvuru: 27/09/2019 Düzeltme: 11/12/2019 Kabul: 21/12/2019

In this study, the effect of using vortex generators in the form of semicircular plates with different angles and at different longitudinal distances in the chimney of a laboratory furnace with natural gas fuel on the hydrodynamics of the flow and the rate of heat transfer from combustion products has been investigated experimentally and numerically. The investigated parameters were angles for blades and the number of blades. The results show that vortex generators with reducing the speed in the central area of the chimney and increasing the residence time of the combustion products and also by directing the flow towards the boundary layer adjacent to the wall, increases the heat transfer to the chimney. The angle of 55º and the number of blades 7 was the optimum condition that prevents the flow of exhaust gases from returning, and in this case, by changing the gas flow rate in the range of 0.5 to 0.75 m3/hr, the heat transfer to the chimney wall increases by 21% on average.

The concept of environmental efficiency in equipments is increasingly in tariff with the unfolding of global warming, and, among the industrial equipments, the burners have a major impact in this discussion because it is an equipment of industrial combustion. Demand for environmentally more efficient burners, with the reduction of emissions is essential for the proper use of fossil fuels during the transition between this energy sources for alternatives energy, which can last more than fifty years. This study evaluates experimentally the technique of oxygen enhanced combustion-OEC-and its interaction with emission rates of formaldehyde and acetaldehyde-precursors for the production of tropospheric ozone and other atmospheric pollutants-in natural gas confined flames. In the experiment was used low enriched with oxygen, which does not require significant existing equipment changes. The emission rates were verified by analysis in liquid chromatography. With the use of oxidizer enrichment of 2 and 4%, the emission rates of formaldehyde and acetaldehyde were reduced with the use of OEC in comparison with the use of atmospheric air as oxidant. The literature show that works with OEC has important points for improving the thermal efficiency of combustion and pollutants reduction. This technology can be an important tool for the adequacy of the industry in general, particularly in oil and gas, for the technological challenge of reducing global warming.

Due to effects of the gating ratio on the amount of shrinkage porosities and thereby on mechanical properties of steel components, optimizing the gating system is one of the interested fields for scientists focused on the casting industry. In this paper, the casting of a steel centrifugal pump body has been simulated and influences of the gating ratio on the casting quality of the obtained component have been evaluated. Investigated parameters involve the place of formed hot-spots, the speed of the liquid flowing from gates and its uniformity. The obtained results show that in the case of the evaluated component, both of the suggested gating ratios of 2:1.15 and 1:3:3 can distribute the melt well in such a way that the last solidified parts are far from the portions experiencing high stresses during the service. However, using the gating ratio of 1:2:1.5 lets that the sprue to be full of the liquid metal. So, the sprue can compensate the occurred shrinkage and almost prevent the entrance of the out gases. Moreover, it was observed that the symmetry of gates with respect to each other does not have an important effect but with respect to the position of the sprue has a crucial role to ensure a similar speed and behavior of the metal flowing in the different gates.

The mode and rate of agitation of the particles is one of the effective variables for dissolving solid particles in the aqueous solution. In the present study, a computer software has been used for simulation of the particle agitation in the pilot mixer reactor. The stirrer speed, pulp density, particle size and solid particles density were selected variables. The effect of above factors on velocity of particles and their accumulation was investigated. The stirrer speed has significant effect on the particle velocity, but by increasing the pulp density, average speed of the particles is more limited. Increasing the size and density of particles can reduce the speed of moving parts. Particle accumulation has increased with increasing pulp density and particle size. The stirrer speed significantly decreases the amount of inactive areas in the reactor. The density of particles does not effect on particle accumulation.

Synthetic slag process decreases sulfur and phosphorus contents of steel, improves inclusion removal, protects steel from atmosphere and prevents temperature drop of the liquid steel in the ladle. In this study, the synthetic slags of ternary CaO-Al2O3-SiO2,and quaternary CaO-Al2O3-SiO2-Na2O and CaO-Al2O3-SiO2-SrO systems were pre-melted and then were kept in contact with the liquid steel in a high frequency induction furnace. The results showed that the optimum reaction time for desulfurization is 15 minutes and the desulfurization efficiency for ternary slag is 33% whereas for the SrO- and Na2O-containing quaternary slags are 34% and 7%, respectively. Furthermore, it was shown that the desulfurization efficiency for SrO-containing slag can be obtained more than doubled (from 34% to 77%) by employing covered crucibles.

New fuels are being produced to replace conventional kerosene to meet the challenges of diminishing fuel resources and environmental issues [1]. However, these new fuels must meet the same standards as conventional kerosene, especially flame stability [2]. However, to optimize the use of these fuels, the choice of the injection system is critical because it will drive the spray characteristics, which will directly impact the flame dynamics. However, decoupling the injection system from flame dynamics in current combustion systems is challenging [3]. In this context, we have designed a burner with an injector capable of generating a spray independent of the fuel properties. The injector is the MTG-01-G3 injector from FMP technology which generates monodisperse droplets spray from a piezo actuator. The injector can generate droplets with diameters in the range of 45µm to 65µm that we control with great precision based on fuel flow rate and piezo frequency. The burner is swirled and turbulent with a mixing zone to properly mix the fuel and the air. The flame is stabilized at the exit of this mixing zone, where it burns in a quartz tube, allowing us to have optical access to the flame. Our study uses conventional and alternative kerosene surrogates with relatively high evaporation temperatures, making them tough to burn at ambient temperature. Thus, to stabilize the flame, we also inject methane which stands for less than half of the global equivalence ratio of the flame. Finally, thanks to this configuration, we have analyzed the effect of physical properties on the spray flame stabilization.

Bu çalışmada, damla sulama sistemlerinde kullanılan hidrosiklon filtre içindeki toplam basınç kaybı ve partikül hareketine bağlı ayırma etkinliği değerlerinin, Hesaplamalı Akışkanlar Dinamiği (HAD) yöntemiyle ortaya konulması amaçlanmıştır. Bu amaçla, E.Ü. Ziraat Fakültesi Tarım Makinaları ve Teknolojileri Mühendisliği Bölümü'ndeki Pompa Deneme ve Araştırma Laboratuvarında basınç (yük) kayıp denemeleri temiz su kullanılarak gerçekleştirilmiş olan 2″, 2½″, 3″ ve 4″ giriş ve çıkış çapına sahip toplam 8 adet hidrosiklon filtre kullanılmıştır. Laboratuvar denemelerinde kullanılan her bir filtrenin tüm boyutları dikkate alınarak katı modelleri oluşturulmuş ve farklı sınır koşulları için RNG k-ε Model, Realizable k-ε Model ve Reynolds Gerilme Modeli (RSM) türbülans modelleri dikkate alınarak akış analizleri Hesaplamalı Akışkanlar Dinamiği (HAD) yazılımı ANSYS Fluent 16.2 yardımıyla gerçekleştirilmiştir. Analizler sonunda, farklı debi değerlerinde ölçülen basınç kayıp değerlerini genel olarak en iyi tahminleyen model, Reynolds Gerilme Modeli (RSM) olmuştur. Bu model ile ayırma etkinliği değerlerine ilişkin simülasyon çalışmaları gerçekleştirilmiş ve yeni dizayn edilen bir hidrosiklon filtrede simülasyon çalışmaları ile partikül ayırma etkinliğinin belirli bir doğrulukla ortaya konulabileceği sonucuna ulaşılmıştır.

Some properties of material such as mass, reaction rate, and volume can be measured as a function of increasing temperature, with controllably burning. These type of analysis are called 'thermal analysis methods'. Generally, thermogravimetric (TG) analysis, differential thermal (DT) analysis, and differential thermogravimetric (DTG) analysis techniques are used to determine the combustion characteristics of combustible materials. Thermogravimetric analyse (TGA) is one of the most common techniques used to determine the combustion properties of materials and to investigate their kinetics rapidly. In this study, the TG analyses were carried out to investigate the combustion characteristics of Beysehir coal. Three different reaction regions were observed in TGA and DTGA curves. The burning profile of the coal sample was investigated by determining the peak temperatures and ignition temperatures. In the kinetic analyses, activation energies were calculated separately for four different reaction orders by using the Coats-Redfern method. It was observed that the moisture of the Beysehir coal moved away between at 25-130 °C, the thermal degradation took place between at 235-540 °C, and the final combustion temperature was 570-690 °C. Weight loss of coal was determined as 28% for the first region, 48% for the second region and 6% for the third region. The ignition temperature and peak temperature were found to be 196 °C and 376 °C, respectively. The activation energies were varied from 8.25 to 18.79 kJ/mol.

High temperatures are often encountered in almost all of the combustion systems, therefore, thermal radiation heat transfer can influence the droplets heat up rate and consequently their life time. In this paper, the effect of thermal radiation heat transfer is investigated for two cases of directional and spherically symmetric illuminations. The flow and temperature fields insdie and outside of the droplet are solved numerically using control volume approach in the presence of thermal radiation. Mie theory is used for the case of directionally illuminated droplet and Dombrovsky’s simplified model is employed for the spherically symmetric illumination to determine the amount and distribution of the absorbed thermal heat inside the droplet. Maximum absorption for a dodecane droplet occurs at the back of the droplet when subjected to directional illumination, while it happens on the surface of the droplet for spherically symmetric illumination. Results show that the heat up rate is less affected by directional radiation whereas spherically symmetric radiation enhances the heat up rate.

Natural convection heat transfer from a vertical heated plate in a saturated porous medium is analyzed under thermal non-equilibrium assumptions. The plate is maintained at a non uniform temperature and the fluid is considered to be with internal heat generation. The coupled momentum and energy equations for fluid and solid phases are transformed to a similarity format, and solved numerically. The resulting velocity and temperature distributions are shown for different values of the problem parameters. Also the values of the local Nusselt numbers for both solid and fluid phases are shown. The effect of suction/injection on the free convection boundary layer is also studied. The obtained results are compared with those presented in the literature in the case of thermal equilibrium model.

In this study, the boiler of Mashhad Toos power plant is studied numerically in order to investigate the possibility to improve its efficiency and reduce its pollutants emission. In this regard, first the current status of the boiler is simulated and the numerical results are compared with the available experimental data, where a good agreement is observed. Next, the effects of the injected fuel droplets’ diameters, air flow rate and the inlet air swirl direction arrangement on the boiler thermal efficiency and pollution emissions are studied. An appropriate arrangement of the inlet air swirl directions for the nine liquid-fueled burners of the boiler is proposed that will lead to a higher boiler thermal efficiency and lifetime.

Diffusion Flame in a Dust cloud combustion in a Counterflow configuration is investigated in this research. It is presumed that the fuel particles vaporize first to yield a gaseous fuel to oxidize with the gas phase. The reaction rate is assumed to be of the Arrhenius type. Conservation equations for the non-unity Lewis number are solved and the flame temperature with the variations of different Lewis numbers of fuel and oxidizer is proposed. Furthermore, the variations of flame position with the variation of Lewis number are evaluated. It has been found that the flame temperature decreases with increasing of fuel and oxidizer Lewis numbers, which for rise of fuel Lewis number from 0.1 to1.4, the flame temperature decreases from 1943 to 1473K.

Due to considerable height of the flaring flames, wind speed has siginificant effects on its flame shape and cause consequent damages. In this paper, the effects of wind speed on the flame shape and the temperature distribution of the flare wall are investigated using three-dimensional numerical simulation of turbulent combustion. Results show that at wind speeds higher than 5m/s, the flame lies over the flare wall causing its temperature to increase. Moreover, as the wind speed changes, the position of the maximum temperature point on the flare wall also changes, causing the material to experience fatigue failure.

In this paper, free convection heat transfer is completely analyzed in a closed cavity containing internal conducting blocks with arbitrary arrangement. Free convection heat transfer in the cavity is studied according to the variations of Rayleigh number, number of conducting blocks, arrangements of blocks and the porosity. The overall Nusselt number as a criterion of heat transfer is reported on the walls of the cavity. The obtained results show that the thermal effects of porosity and the arrangements of blocks in the cavity are less than the effects of Rayleigh number. However, increasing the number of blocks inside the cavity leads to a decrease in the overall Nusselt number.

In the nuclear fuel assembly, the mixing vanes are solid components which are attached to the spacer grid. These vanes would increase heat transfer rate from the fuel wall. The force induced by flow may expose the vanes to excessive stress and bending, which in turn, it impairs the mixing vanes. In order to improve the heat transfer rate and decrease the vibrational forces, vanes are usually positioned at a certain angle regarding to the flow axis. This study investigates displacement of vanes in three angles of 65, 70 and 75 degrees for a specific geometry using the fluid-solid interaction method. First, the fluid flow is solved using a Finite Volume Method (FVM) solver and the forces exposed by the flow to the vanes are estimated. Next, the displacement of the vanes due to the applied forces is calculated by the Finite Element Method (FEM). Comparison between calculated pressure drop in this study and experimental result show a difference less than 10%. The maximum pressure drop is occurred when the vanes have 65° angle. The most turbulence intensity is obtained at the angle of 75°. Also, according to the frequency estimation, it was observed that with increasing frequency the displacement's amplitude would decrease.

In the present study, with the aid of computational fluid dynamics tools three different radiant tubes including straight, u-shape and w-shape were compared. After designing the geometry, the grids generated for geometries in Gambit software. Grid independence was also performed for the W-shaped geometry, which was the most complex geometry. Firstly, the results showed that the amount of nitrogen oxide emission in the U-shaped radiant tube is the highest compared to direct and W-shaped radiant tubes and the lowest was in the W-shaped type. W-shaped radiant tube had the highest efficiency (55.3%) among all radiant tubes. Besides, the ratio of radiant heat transfer from the tube wall surface to the total heat transfer from it in all three types of radiant tubes was high and more than 90%. By moving away from the wall of the radiant tube in all tubes, the amount of radiation per unit area decreases. Furthermore, the highest amount of radiation intensity was devoted to the W-shaped tube, then the U-shaped tube, and finally the lowest amount was related to the direct tube.

This paper studied the oxygen flow distribution in a PEM fuel cell stack numerically. At first, the flow in the
stack was simulated as a single phase, and the effect of gradual reduction of manifold height (tapered manifold) on
improving the flow distribution between fuel cells was investigated. Standard deviation and non-uniformity coefficient
have been used to measure the flow maldistribution. Gradual reduction of manifold height up to 70% in the tapered
manifold improved standard deviation and non-uniformity coefficient by 6.9% and 8.4%, respectively. The results of the
two-phase simulation showed that the condensation of water vapor in the saturated oxygen could cause the accumulation
of liquid water at the end of the manifold. As the smaller droplets merged, the droplet radius formed at the end of the
manifold increased until it detached from the manifold wall and entered the last cells. Less liquid water entered the last
cell at shorter intervals in the tapered manifold. It was suggested that by creating a water chamber at the end of the
manifold, condensed water be collected from the manifold and discharged from the stack. Increasing the mass flow at the
manifold inlet and discharging the excess gas through the water collection chamber can push the liquid water into the
chamber without causing significant changes in pressure drop.

Carbonation Calcination P CO2 eq, atm Temperature (ºC) Next steps in Ca-looping development: 1.7 MWt pilot plant Facility area Calciner operating under air or oxy-combustion conditions Removable cooling bayonet tubes to change heat extraction in reactors O 2 and CO 2 tanks and gas mixer, to change oxy-combustion ratio Calciner gas heater and indepent steam inyection Gas velocities similar to those found in CFB boilers (3-5 m/s) Next steps: 1.7 MWt pilot plant Complete instrumentation (temperature, pressure, solid samples) FP7 "CaOling" Project: Development of postcombustion CO2 capture with CaO in a large testing facility: www.caoling.eu To advance in the experimental validation of the carbonate looping cycle (at a 1.7 MWt scale range) and demonstrate that this is a low cost, highly energy efficient CO 2 capture technology, suitable for retrofitting coal combustion power plants

Due to the increase in population and economic growth of the nation, particularly in growing countries like India, has resulted in huge demand of energy sources. Due to reduction of non-renewable petroleum sources and recent hike in petroleum prices and lack of availability of petroleum products have generated interest in extraction of energy from renewable energy sources wherein the biodiesel plays an important role which is derived from plant origin for diesel engines. This research work refers to the biodiesel production by the process of transesterification of Calophyllum inophyllum oil with methanol as a solvent, calcium oxide (CaO) as a catalyst. The obtained Calophyllum inophyllum biodiesel (methyl ester) from transesterification process is blended with the neat diesel in required proportion such as B10, B20, B30, B40 and B100 and their properties such as flashpoint, fire point, kinematic viscosity, etc., are examined and used to run 4-stroke, CI engine without making any mod...

In this study, experimental results from a homogenous charge compression ignition (HCCI) engine fueled with PRF85 (85% iso-octane and 15% n-heptane) were used to zero dimensional In this study, combustion analysis of homogenous charge compression ignition (HCCI) engine are examined. In the analysis, chemkin-pro software was used which can analysis 0-D combustion and chemical mechanism. Anlysys results are compared with the results of Shell research center. With the help of Chemkin-Pro, results of experiments and various combination mechanisms results can be easily compared. Prepared chemical kinetic mechanisms exist in order to make the analysis inside the engineer. Two chemical kinetic mechanism which is compatible to PRF fuel are used inside the experimental engine. Two different chemical which were developed for the same fuel are examined based on performance similarities on the experiments. Besides, effect of solvents and mechanism on total analysis time are also studied as perf...

In this work, SO 2 retention via calcium-based sorbents added in a continuous bubbling fluidized bed combustor (~3 kWth) operating in oxy-fuel combustion mode is analyzed. Tests were performed at different operating temperatures with three sorbents, two limestones and one dolomite, and with three coals, ranging from lignite to anthracite, to analyze the influence of coal rank, type of sorbent, sorbent particle size, and O 2 /CO 2 feeding ratio on the sulfation process. It was found that the combustor temperature had a strong influence on the limestones sulfur retention with a maximum at 900-925 ºC. The behavior of the limestones was qualitatively similar with the three coals, attaining the highest sulfur retention values

Sulphur capture by calcium-based sorbents is a process highly dependent on the temperature and CO 2 concentration. In oxy-fuel combustion in fluidised beds (FB), CO 2 concentration in the flue gas may be enriched up to 95%. Under so high CO 2 concentration, different from that in conventional coal combustion with air, the calcination and sulphation behaviour of the sorbent must be defined to determine the optimum operating temperature in the FB combustors. In this work, the SO 2 retention capacity of two different limestones was tested by thermogravimetric analysis at typical oxy-fuel conditions in FB combustors. The effect of the main operating variables affecting calcination and sulphation reactions, like CO 2 and SO 2 concentrations temperature and sorbent particle size, was analysed. It was observed a clear difference in the sulphation conversion reached by the sorbent whether the sulphation takes place under indirect or direct sulphation, being much higher under indirect sulphation. But, in spite of this difference, for a given condition and temperature, the CO 2 concentration did not affect to the sulphation conversion, being its major effect to delay the CaCO 3 decomposition to a higher temperature. For the typical operating conditions and sorbent particle sizes used in oxy-fuel FB combustors, the maximum sorbent sulphation conversions were reached at temperatures of about 900 ºC. At these conditions, limestone sulphation took place in two steps. The first one was controlled by diffusion through porous system of the particles until pore plugging, and the second controlled by the diffusion through product layer. As a consequence, the maximum sulphation conversion increased with decreasing the particle size and increasing the SO 2 concentration. *Manuscript Click here to view linked References

and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.