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Production, performance and emission studies of municipal and medical waste plastic fuels and its blends with diesel
The basic aim of this study was to examine the usage of plastic municipal and medical waste, as an alternative source to diesel fuel. For this study; waste plastic materials, obtained from municipal and medical wastes, were used. Waste plastics were transformed to waste plastic fuel by thermal cracking. Municipal and medical waste plastic fuels were blended with diesel fuel at volumetric ratios of 10%, 20% and 50%. Fuel properties of waste plastic fuels and its blends were analyzed in accordance with the standards of American Society for Testing and Materials (ASTM) methods. In addition to fuel properties, engine performance and exhaust emission studies of waste plastic fuel-diesel blends were carried out. Key Words: Engine Performance, Emissions, Fuel Properties, Thermal Cracking, Municipal and Medical Waste Plastic Fuel
Design, analysis and optimization of chassis for an electric vehicle
The purpose of this study is to design rigid and lightweight chassis for an electric vehicle. Design criteria and constraints are obtained from the TÜBİTAK electromobile racing rules. Various chassis types with different geometries are considered and 18 units of chassis are designed using computer aided design (CAD) software. Designs are analysed using finite element analysis (FEA) software and performance characteristics are parametrically and structurally optimized. Final design has aluminium 5042 H¬-19 space frame structure type and weighs 28.163 kg. Maximum von-Mises stress of the design is 15.465 MPa and the value is far below the material's yield strength of 345 MPa. Torsional stiffness value of the chassis is generated from the result of 2.495 mm maximum torsional deformation and calculated as 1828.289 Nm/deg.
Design and development of a light weight composite chassis for electric vehicle applications
Today, the vehicle technology is being transformed due to environmental impact of fossil fuel and their uses. Especially studies appear to be directed towards development of lightweight and durable chassis system. In this way, along with achieving fuel economy in existing systems, the need for lightweight chassis for electrically powered vehicles are met. In recent years, stress analysis studies using the finite element method has made significant contributions to the design engineering. With the help of a computer software, stress and deformation analysis of a system can be achieved with very small margin of errors at very much realistic values. As a part of the study, some sample carbon fiber-epoxy composite material was manufactured and tested. Considering the test results obtained, a car chassis for two passengers is designed using SolidWorks software. The developed composite and aluminum based chassis have been analyzed on the ANSYS software and the development of the chassis has been completed successfully.
Investigation of diesel and biodiesel fuels effects on energy and exergy analysis in diesel engines
In this study, both First and Second Laws of Thermodynamics are employed to take into account the quantity and quality of energy.Energy and exergy analyses applied using experimental data obtained from a four stroke, four cylinders, naturally aspirated, having 1800 rpm direct-injected diesel engine using different fuels. Air and fuel flow rates, engine speed, emissions, relevant temperatures are needed to be able to perform the first and second law of thermodynamics. With the use of these data and balances of energy and exergy rates for the control volume, 1st and 2nd law (energy and exergy) efficiencies related with quantity and quality were determined for various fuels. All results were compared with each other to determine fuel effect on energetic and exergetic performance. In conclusion, It was determined that diesel fuel showed better energetic and exergetic performance than both biodiesels of cotton and soybean.
Development of seat design and simulation of seating systems' tests according to european and us regulations for seats
Today, due to the increment of energy consumption and greenhouse emissions, there is an extraordinary effort to overcome these problems in transportation sector. One of the most effective means to reduce fuel consumption and greenhouse gases is weight reduction of the vehicles. In transit vehicle sector, when the ratio of overall vehicle weight is analyzed, passenger seats have a significant energy saving potential. When studies are analyzed, it can be understood that two main ways are used to reduce the weight of the seat; using high strength steel and optimizing the design by using lightweight material instead of steel. The primary objective of this study is to obtain a weight reduction for passenger seats by using different materials for design and compare weight and strength of seat designs. This passenger seats were designed without compromising any comfort criteria and tested by using simulation program according to the FMVSS, APTA and ECE R80 regulations. Consequently, 31% weight reduction was obtained by using ultra high strength steel and 50% weight reduction was obtained by using aluminum alloy for design.
Analysis of production parameters of biodiesels derived from canola, palm and cotton oils
Biodiesel is an alternative fuel for diesel engines that is gaining attention in last years. Its primary advantages are that it is one of the renewable fuels currently available and it is also non toxic and biodegradable. It can be also used directly in most diesel engines without requiring extensive engine modifications. Due to increase, environmental pollution and suitability of fossil fuels have lead to concerns in the looking alternative fuels for diesel In this regard to replace diesel fuel with oxygenated fuel such as biodiesel. Mainly biodiesel refers to a vegetable oil or animal fat based diesel fuel consisting of long chain alkyl (methyl, ethyl or propyl) esters. Biodiesel typically made by chemically reacting lipids (eg. Vegetable oil,soybean oil, animal fat (tallow)) with an alcohol producing fatty acid esters.And various types of catalysts that have been used to effect the transesterification of vegetable, waste and animal oils in biodiesel production. Aims of this thesis, is evaluation of biodiesel production parameters on the effect of biodiesel conversion rate.
Effects of engine parameters on performance and emission characteristics of a variable compression ratio engine
This study investigates the performance and emission characteristics of a variable compression engine which is fueled with alternative fuels such as biodiesel and diesel-biodiesel blends. Camelina Sativa (false flax) oil which has variety of usage and has a potential of being feedstock for biodiesel production were used as alternative fuel. Also various common oils such as sunflower and canola oil were used as feedstocks for biodiesel production. Experimental study was conducted with a four stroke, single cylinder, naturally aspirated, multi fuel variable compression ratio engine by using diesel and alternative fuels. Experiments were performed at 1500 rpm and under partial load condition with three different compression ratios. Theoretical study was performed with the aid of Diesel RK software. Technical specifications of test engine were modelled using Diesel RK software and performance and emission characteristics were evaluated and compared with experimental results. The study showed that, increasing compression ratio significantly improves thermal efficiency and specific fuel consumption of the engine for all test fuels. The engine emitted lower carbon monoxide emission but higher carbon dioxide and nitrogen oxides (NOx) emission when operated at higher compression ratios. Furthermore, biodiesel usage increased specific fuel consumption slightly. The engine emitted lower carbon monoxide emission but, higher nitrogen oxides (NOx) emissions when biodiesel used as fuel.
Investigation of mechanical and thermal properties of boron minerals doped plastic materials
In this study; mechanical and thermal properties of boron containing polyethylene and polyurethane was investigated. This thesis consists of two main parts that are polymer manufacturing and characterization. Polymer blends are manufactured by extrusion method within the limits of 15% boron mineral content followed by using the injection molding method to obtain tensile and impact tests samples. To understand the mechanical properties of the samples, tensile test, impact test and hardness test is utilized. Additionally, thermal characteristics and properties are investigated using Thermogravimetric analysis and Differential Scanning Calorimetry. Experimental data showed that there is no significant decrease in tensile strength of the materials and a notable increase in stiffness of materials. In addition, polyethylene based samples indicate a decline in elongation at break whereas there is a variety of results obtained from polyurethane samples. While there was a notable decrease in the impact resistance of polyethylene-based materials, contrary to expectation there has been an increase in some polyurethane based samples. Hardness values are found to be improved for both sample types. Similar results were obtained in the two methods used for analysis the thermal properties. Although it is not as much as expected, there is a noticeable improvement in the thermal properties of both materials. Additionally, while Scanning Electron Microcopy (SEM) was utilized to monitor the dispersion of mineral filler, Melt Flow Index (MFI) measurements were used to determine the flow dynamics that are important for production. SEM images reveal that mineral filler is not as well-dispersed as expected. When the flow properties were examined an increase in viscosity was observed as expected, except for some samples.
Thermodynamic simulation of transcritical organic rankine vapor compression refrigeration system using low GWP refrigerants
Due to critical level of greenhouse gas emissions and rising petroleum prices, governments have issued strict regulations for internal combustion engine emissions and fuel economy standarts. Organic Rankine cycle is a promising way to recover engine exhaust waste heat and reduce fuel consumption. In this thesis, parametric thermodynamic analysis of transcritical organic Rankine vapor compression (T-ORVC) refrigeration cycle using internal combustion engine exhaust waste heat is investigated. Two low Global Warming Potential (GWP) fluids are considered as refrigerants for the potential replacement of high GWP refrigerant R134a. Throughout the theoretical study, refrigerant boiler pressure, cycle component efficiencies and temperature of condenser/evaporator and the degree of subcooling/superheating are used as parameters to simulate all possible scenarios. Results revealed that both low GWP working fluids have cooling performance close to R134a. Moreover, T-ORVC refrigeration system with R1234ze(E) presented slightly higher thermodynamic performance throughout the operation conditions. Study indicated that, R134a can be replaced by studied low GWP working fluids for the proposed system.
Energy and exergy analysis of an inter-city bus air-conditioning system working with different refrigerants
In this thesis, energy and exergy analysis of inter-city bus air conditioning (ICBAC) system are performed using different refrigerants and air mixing ratios (MRs). Adana province of Turkey was chosen as the study region. Firstly, a coach bus, which is used for inter-city passenger transportation in USA, with a passenger capacity of 56 persons was selected. Hourly Analysis Program (HAP) was used to determine the hourly cooling load capacity of the selected inter-city bus model. In cooling load calculation of the inter-city bus, climate data such as dry bulb temperature, wet bulb temperature and solar radiation of the Adana province were used. Commonly used refrigerants R404A, R410A, R502, R507, R22, R290, R134a, R500 and R600a were selected for use in the ICBAC system. Obtained Coefficient of Performance (COP), exergy efficiency and exergy destruction values of ICBAC system and its components for July were evaluated. Results reveals that the performance of the ICBAC system was substantially affected from refrigerants and MRs, and R600a has the minimum total exergy destruction among all studied refrigerants. Minimum total exergy destruction value of R600a was obtained as 3.88 kW for MR=0.05, and maximum total exergy destruction value was calculated as 7.02 kW for MR=0.5.
Use of ethyl alcohol as a reductant agent in a SCR system at low temperatures
In this study, Ag / Cu based catalyst was synthesized with the impregnation method for hydrocarbon-selective catalytic reduction (HC-SCR) system. In this system, a mixture of ethyl alcohol and distilled water was used as a reducing agent and the effect of the synthesized catalyst on NOx conversion efficiency was investigated.The analysis done by SEM, XRD, and BET revealed the structural and chemical peoperties of the catalysts. In the SCR exhaust test performance system, experiments in a temperature ranging from 170°C to 260°C, and 2 different space velocities SV(20000h-1, and 40000h-1) were conducted using the prepared catalyst. The tests were conducted using a 2 cylinders, V-type diesel motor with constant speed(3000r/m), and in 4 different engine loads(1,2,3, and 4KW). These tests determined the effects of SCR catalyst over NOx emissions rate. In colclusion, NOx converison rates changed approximately between 55% and 65%. The highest NOx conversion rate recorded in the tests was approximately 68% at 4KW engine load, 100% ehtyl alcohol spraying, and SV=20000h-1.
Improving of crawler excavator cabinet acoustic isolation with synthetic sound barrier and polyethylene insulations materials
In this thesis, the sound level of a crawler excavator with a weight of 30 tons was determined and it was aimed to reduce the sound isolations in the cabin and the sound absorbers in the outside environment. Within the scope of the research, the openings that would affect acoustic isolation of excavator cabin were determined. Solutions suitable for these openings were developed. As a result of the tests, the highest decibel values of the excavator operating conditions, the frequency range corresponding to this value were determined. Appropriate isolation and sound absorbers were determined for these frequency ranges. Synthetic sound barrier is mounted on the cabin floor and polyethylene sound isolations are mounted on the cabin frame.as a result, the cabin noise level has been reduced by 3-5 dB Thus, a more comfortable and quiet operator area was obtained for the excavator.
Determined the operation modes on compact hydraulic excavator and their effects of fuel consumption and hydraulic system in real working condition
In this thesis, the effects of the actual operating conditions of the compact hydraulic excavator on the hydraulic system and fuel consumption were investigated. In this context, hydraulic pressure, hydraulic flow, instant fuel consumption, attachment cycle time values and average fuel consumption values were determined. For the compact hydraulic excavator, hourly fuel consumption and cycle time values were analyzed. The hydraulic pressure and flow values of the piston and gear pump are presented in the study depending on the time. Separate tests were carried out for operation modes. According to the data obtained, system limit values were determined. Cycle time values of machine attachment movements were obtained and the suitability and efficiency of operation modes were determined. The effects of trench digging, straight travelling, soil levelling and standby idling on the system and fuel consumption have been demonstrated. According to all data, results are presented for efficient operation modes.
Investigation of propanol-adblue blends as a reductant agent in a SCR system
In this study, Ag-Pd-Ti based catalyst was synthesized with the impregnation method for hydrocarbon-selective catalytic reduction (HC-SCR) system. In this system, a mixture of propanol and adblue was used as reducing agents and the effect of the synthesized catalyst on NOx conversion efficiency was investigated. The analysis done by SEM, XRD, and BET revealed the structural and chemical properties of the catalysts. In the SCR exhaust test performance system, experiments in a temperature ranging from 170°C to 300°C, and 1 space velocity SV (30000h-1) were conducted using the prepared catalyst. The tests were conducted using 2 cylinders, V-type diesel motor with constant speed(3000r/m), and in 4 different engine loads (1, 2, 3 and 4 KW). In conclusion, NOx conversion rates changed approximately between 42% and 68%. The highest NOx conversion rate recorded in the tests was 68,1% at 4KW engine load, 100% propanol spraying and SV=30000h-1.
Energy and exergy analysis of a proton exchange membrane fuel cell (PEMFC)
This study investigates the thermodynamic performance of a 1 kW self-humidified Proton Exchange Membrane (PEM) fuel cell. The first law analysis of thermodynamic is performed both experimentally and theoretically and the second law analysis or thermodynamic is performed at different operating temperature ratio (T/T0) varies from 1 to 1.2 and operating pressure ratio (P/P0) varies from 1 to 2 for different power output. Hydrogen is used as a fuel and in order to perform the thermodynamic analysis hydrogen, air, product water and exit air flow rates and specific physical are calculated. The energy and exergy balances for the control volume are used to calculate the efficiencies of energy and exergy of the PEM fuel cell. All results were compared with each other to see the effects of operating temperature and pressure on performance. As a result, it was observed that both increment in operating pressure and operating temperature improves the exergetic performance.
Static analysis of two seater extended range electric vehicle
Electrical driven vehicles are becoming an attractive alternative to combustion engine cars. Electric vehicles will play quite an important role in reducing emissions in the future. One of the most effective ways for reducing fuel consumption and emissions can be achieved by reducing weight of the vehicle. The vehicle chassis is one of the most important components of vehicle structure because of its versatile role on the dynamic behavior of the vehicle. There is a great potential for weight reduction of the chassis. This study presents the design and development of a two-seat prototype electric vehicle chassis. The main objectives are designing a battery module that can be easily attached and detached to the battery module compartment of the chassis, designing a new chassis model and ultimately evaluating the chassis for deformation based on static analysis of the entire structure. Vehicle designs and analyzes were done with Catia V5 R20 software. AL6061, ST-37 and carbon fiber materials are preferred for chassis.
Effect of spark plug alteration on performance and emissions using hydrogen enriched gasoline in si engine under various loads and compression ratios
In this study, performance and emission parameters of a variable compression spark ignited engine was investigated with different spark plugs and hydrogen enrichment. The tests were carried out with a four stroke, single cylinder, naturally aspirated, variable compression ratio (VCR) engine. Two different compression ratios (CR) of 8.5:1 and 10:1 under %50 part throttle condition were implemented throughout the experiments. Moreover, engine loads of 8 Nm, 13 Nm and 17 Nm were applied to evaluate effects of different spark plugs and hydrogen usage at different engine loads. Copper, iridium and platinum spark plugs were tested for each experiment condition. In addition, hydrogen was added through the intake manifold with flow rates of 0, 2 and 4 lit/min to enhance combustion of VCR engine. Brake power (BP), brake specific fuel consumption (BSFC), carbon monoxide (CO), carbon dioxide (CO2) nitric oxides (NOx) and unburned hydrocarbons (UHC) values were determined with this study. According to test results, iridium and platinum spark plug usage, hydrogen addition and higher compression ratio improved BP and BSFC values and the engine emitted lower CO and UHC. However, higher CO2 emitted because of increased completeness of the combustion and NOx gases have risen due to increment in-cylinder temperatures. These variances occurred more obvious with platinum spark plug usage comparing to iridium spark plug. In addition, effects of spark plug alteration, hydrogen addition and higher CR on enhancements of BP, BSFC and CO were comparatively lower at higher engine loads.
Hydrogen enriched biodiesel usage in compression ignition engine
In this study, Biodiesel production has been acquired with using waste oil. Following this, pure hydrogen has been added 4 liter/min, 8 liter/min and 12 liter/min to the test fuels which are 100% Biodiesel, 100% Diesel, 90% Diesel + 10% Biodiesel and 80% Diesel + 20% Biodiesel. Brake thermal efficiency is higher in diesel fuels than WOB + Diesel fuels. Higher brake thermal efficiency has been obtained more than diesel fuels using with hydrogen in WOB+ Diesel fuels. BSFC increased using with WOB usage while decreased by addition of Hydrogen. Using with Hydrogen and Waste Oil Biodiesel usage together, CO emissions were decreased comparing to pure Diesel. In Biodiesel fuels, CO2 and NOx emission values were acquired more than Diesel fuels. CO2emissions have been decreased with hydrogen enrichment. However, NOx emissions have been increased with hydrogen enrichment.
Simulating friction and wear behaviour of a brake pad using different materials
The brake pads used in automotive brakes are made from the composition of many substances. The main features required from a brake pad are wear resistance in accordance with the standards, friction coefficient. The brake pads overheat due to friction during braking. In this study, the performance characteristics of the brake pad obtained by using the materials that make up the lining content were investigated in the simulation environment. In this context, brake disc and pads which are different contents are designed using CATIA V5 Program. The pads designed are simulated using ANSYS program and the wear rates, friction coefficient thermal behaviors and surface structure are examined. Keywords: Break pad, Ansys, Friction, Wear, Thermal Analysis
Computational heat and fluid flow analysis of an innovative plate for a plate heat exchanger
In this study, heat transfer and fluid flow are numerically investigated for interrupted sinusoidal channels with ANSYS Fluent software under the assumptions of 2D viscous, incompressible, fully developed laminar flow. For this aim, an innovative sinusoidal geometry was created and used. Since the flow was periodically repeated, the periodic boundary condition was used to save computational time. Before the main computations, validations were performed to ensure the accuracy of the solutions. Effects of the sinusoidal wave amplitude, the thickness of the wall, space between interrupted channels, and vertical distances on Nusselt number, friction factor, and thermal enhancement factor were investigated for different Reynolds numbers. Velocity vectors, velocity contours, and temperature contours were also shown. Results from the study shown that this type of channel has increased the Nusselt number and friction factor due to the vortex generation.
Numerical investigations of curved slanted surface and lower deflector on the Ahmed body
The effects of passive control models on aerodynamic drag and near wake structures of an Ahmed body with a 25° slant angle was numerically studied. 4 different control methods were studied for this purpose. Curvature control method consists of a curved upper edge of the slanted surface. The radius of the curvature was started from 200 mm and ended at 1000 mm radius. Deflector control method consists of a deflector attached on the lower edge of the slanted surface. Length of these deflectors was started from 1% of the body length and ended at 6% of the body length. Later on, based on the best-resulted curvature and deflector control models, a new control model created and called the optimum control method. Lastly, a deflector was relocated on the slanted surface and the deflector end was aligned to the end of the body vertically. Simulations were conducted in Fluent (19.1) software at 60 m/s inlet velocity, which it was equal to Reynolds number = 4.2 x 〖10〗^6. The obtained results and displayed flow structures were compared with the base Ahmed body result. As a result of these simulations, the coefficient of drag was reduced up to 21.16%. Key Words: Drag Coefficient, Lift Coefficient, Ahmed Body, CFD
Fabrication and characterization of expanded polystyrene/chopped glass fiber/epoxy novel composite
This study investigates the fabrication and characterization of a novel composite material that consists of expanded polystyrene beads as filler, chopped glass fibers as reinforcement and epoxy resin as matrix. Material samples were fabricated with vacuum infusion technique. Experimental studies were carried out at two stages. At the first stage, a bulk material was fabricated and three different types of specimens were cut to determine the material behavior when material is tested in different directions. At the second stage of the study, specimens with different ingredient ratios were fabricated. 14 different specimen types with varying parameters were fabricated, characterized and compared with neat resin. Experimental studies of first stage revealed that, the novel composite possess quasi-isotropic properties although it has non-homogeneous nature. The novel composite has significantly low density and thus considerably high specific modulus value. The second stage revealed that, the optimum fiber/filler ratio for the novel composite is 20:1. At higher ratio than 20:1, the increased clustering regions deteriorated the properties of the composite and caused high variation in results. The cost analysis showed that the expanded polystyrene/glass/epoxy composite have significantly high cost-property efficiency which means the novel composite is a good candidate for many engineering applications.
Bir model kara taşıtının (Ahmed Body) geometrik modifikasyonlarının hesaplamalı akışkanlar dinamiği analizi ve optimizasyonu
Bu çalışmada 35°'lik arka eğim açısına sahip olan model kara taşıtının (Ahmed Body) aerodinamik verimliliğini arttırmak için modelin arka kısmına plaka yerleştirilmiş, tavan paneline belirli oranlarda eğim verilmiş ve alt gövdenin arka uç kısmına 10°'lik bir açı verilerek model kara taşıtının (Ahmed Body) geometrisi değiştirilmiştir. Bu geometrik değişiklikler model kara taşıtına (Ahmed Body) ayrı ayrı uygulanıp daha sonrasında bir araya getirilerek model kara taşıtının (Ahmed Body) aerodinamik katsayılarına olan etkisi incelenmiştir. Model kara taşıtına (Ahmed Body) Reynolds sayısı 2,8x106 olarak alınarak ve k-epsilon türbülans modeli seçilerek hesaplamalı akışkanlar dinamiği analizi farklı geometrik modifikasyonlara ait modellere uygulanmıştır. Sürükleme ve taşıma katsayılarında azalma elde edilmiştir. Anahtar Kelimeler: Sürükleme Katsayısı, Taşıma Katsayısı, Model Kara Taşıtı Hesaplamalı Akışkanlar Dinamiği, Geometrik Modifikasyon
Mini insansız hava araçlarının havada kalma süresini artırmak amacıyla çoklu hibrit güç paketi geliştirilmesi
İnsansız hava araçları (İHA) her geçen gün yeni görev ve amaçlarla kullanımı yaygınlaşan sistemlerdir. Son zamanlarda İHA sınıfları içerisinde sertifikasyon, üretim, maliyet gibi birçok konuda avantajları nedeniyle mini-İHA'ların kullanımı öne çıkmaktadır. Bu tez çalışmasında mini İHA'ların temel sorunlarından biri olan havada kalma süresi kısalığına çözüm getirmek amacıyla çoklu hibrit güç sistemleri geliştirilmiştir. Hidrojenle çalışan yakıt hücresi, lityum polimer batarya, güneş paneli ve süper kapasitör sistemlerinin kullanıldığı hibrit yapılara ilişkin algoritmalar oluşturulmuştur. Güç yönetim sistemi (GYS) tasarımı gerçekleştirilerek oluşturulan hibrit itki elemanları aralarında geçişler sağlanmıştır. İtki sisteminin yer testleri statik ve dinamik yük altında gerçekleştirilerek, önerilen iki hibrit modelin sonuçları çalışma kapsamında değerlendirilmiştir. Çalışma sonucunda önerilen hibrit sistem elemanları ve GYS algoritması ile model mini-İHA'nın havada kalma süresini bataryalı modele göre 3 kattan daha fazla arttırabildiği gözlemlenmiştir. Ayrıca çalışma kapsamında yakıt hücrelerinin mevcut düşük güç yoğunluğu nedeniyle uygun süper kapasitörler ile kullanımının güvenilirlik ve batarya performansı açısından faydalı olacağı sonucuna varılmıştır.
Taşıtlar için yeni nesil otomatik yangın söndürme sistemlerinin geliştirilmesi
Taşıtlarda oluşan yangınlar, maddi ve ölümlü birçok kayba neden olmaktadır. Bu tez kapsamında; taşıt yangınları için günümüzde kullanılan çeşitli söndürme sistemleri incelenerek, tüm yönleri ile araştırılmıştır. Taşıt dünyasında kullanımı hızla artan elektrikli araçlarda kullanılan lityum iyon pil ve batarya paketleri için de yanma, söndürme ve soğutma çalışmaları yapılmıştır. Yapılan denemeler LIT-A, LIT-B, LIT-C, BUS, IM ve MET denemeleri olarak sınıflandırılmış ve toplamda yirmi altı adet deneme yapılmıştır. Denemelerde; lityum iyon pil ve bataryalar, hurda bir otobüs ve aktif olarak çalışan bir iş makinesinden faydalanılmıştır. Sulu, aerosollü, karbondioksitli, bor esaslı ve yangın söndürme topu olmak üzere çeşitli yangın söndürme ürünleri denenmiştir. Tasarlanan otomatik yangın söndürme sisteminde; ikili dedektör ile algılama yapan bir sistem kurgulanmıştır. Ayrıca yangınlara otomatik müdahale edilebilmesi adına kontrol paneli tasarımı yapılmıştır. Yapılan denemelerde aerosolün söndürme işleminde başarılı ve sonrasında tortu bırakmayan bir yapıda olduğu görülmüştür. CO2 ve yangın söndürme topu ise yangın söndürme işlemlerinde sıcaklık düşüşünü istenen oranda gerçekleştirememiştir. Bor esaslı yangın sondürme/soğutma ürünlerinin termal kaçak başlangıcında ve yanma eğilimindeki lityum iyon pil ve bataryalarda başarılı olduğu tespit edilmiştir. Bor esaslı ürünlerin geleceğin taşıt dünyasında hem söndürmede hem de soğutmada etkin olacağı görülmüştür.
UNECE R66.02 regülasyonuna göre dinamik analiz yazılımını kullanarak yapılan M3 kategori araç üst yapısının devrilme testinin bilgisayar simülasyonu
Devrilme en tehlikeli ve ölümcül araç kazalarındandır. Bu nedenle araç üreticileri, yolcu güvenliğini garanti altına almak için ürettikleri araçların üst yapısının sağlamlığından emin olmalıdır. Bu nedenlerden dolayı UNECE R66 yönetmeliği ilk olarak 1997 yılında yayınlanmıştır. Bu çalışmada, aracın üst yapısının direncini ve yolcu yaralanma risklerini değerlendirmek için M3 kategorisindeki bir otobüsün devrilme kazasında mukavemeti ve yapısal davranışı simüle edilmiştir. Söz konusu sanal devrilme simülasyonu analizi, UNECE (Birleşmiş Milletler Avrupa Ekonomik Komisyonu) 66.02 numaralı yönetmeliğinin güvenlik yönetmeliğine göre yapılmıştır. Anahtar Kelimeler: Araç Devrilmesi, UNECE R66, Araç Üst Yapısının Dayanma Gücü, Sanal Araç Devrilme Analizi, Kategori M3 Araç Devrilmesi, Otobüs Devrilmesi, Sonlu Eleman Analizi
HC-SCR sisteminde Ag/kordiyerit katalistlerine Cu ilavesinin Ca zehirlenmesine etkisi
Bu çalışma esnasında, Hidrokarbon Seçici Katalitik İndirgeme Sistemi (HC-SCR) sistemi için Ag/ TiO2, Ag-Ca/TiO2, Ag-Ca-Cu (%0,5) /TiO2, Ag-Ca-Cu (%1) /TiO2, Ag-Ca-Cu (%1,5)/ TiO2 bazlı katalistleri emdirme yöntemi kullanılarak üretilmiştir. Bu sistemde indirgeyici madde olarak etil alkol kullanılmıştır. Üretilen katalizörün kullanıldığı sistemin NOX dönüştürme verimliliği analiz edilmiştir. Kullanılan katalizörün kimyasal ve yapısal özellikleri SEM, BET ve XRD analizleri ile incelenmiştir. SCR test sisteminde deneyler,180°C ile 270 0C arasında değişik sıcaklıklarda, sabit gaz saatlik alan hızında (30000 h-1) gerçekleştirilmiştir. Testler 3 farklı yük (1 kW, 3 kW ve 5 kW) altında sabit motor hızına (3000 devir/dk) sahip, 2 silindirli V tipi dizel motor kullanılarak yapılmıştır. Bu testler üretilen katalistin SCR sisteminin NOX dönüştürme oranı üzerindeki etkilerini tanımlamıştır. Sonuç olarak, maksimum NOX dönüşüm oranları 5 kW yükte, 270 0C sıcaklıkta, 30000 h-1 gaz saatlik alan hızında ölçülmüştür. NOX dönüşüm oranı en yüksek nokta olan %93,84 noktasına ulaşmıştır.
Seçici katalitik indirgeme sistemleri için hibrit katalist sentezlenmesi ve performans özelliklerinin incelenmesi
In this study, it was aimed to produce catalysts with different metal nanoparticle materials to be used in the ethanol-selective catalytic reduction (SCR) systems and then to determine the nitrogen oxide (NOx) emission conversion performances of these catalysts. Firstly, two separate series of silver (Ag) based catalysts containing cerium (Ce) and copper (Cu) were produced, and then their structural properties were detected by SEM, XRD, and BET analyses. Finally, tests for NOx conversion efficiencies were performed on the SCR performance test system. Test conditions were determined as a temperature range of 200 ℃ to 300 ℃, the constant space velocity of 40000 h-1, and 4 different engine loads (1 kW, 2 kW, 3 kW, and 4 kW). The emission gas used in the tests was the actual emission gas originating from a 2-cylinder V-type diesel engine with a constant engine speed of 3000 rpm. Depending on the increment in the exhaust gas temperature from 200 ℃ to 300 ℃, the NOx conversion efficiencies of all catalysts improved. As a consequence of the tests, the best activity was obtained as NOx conversion efficiency of 92.48% at 300 ℃ at 4 kW engine load over the 5A5CT catalyst. Ce additive played a promotive role in the NOx reduction performance of Ag based catalyst. However, Cu doped catalysts achieved a lower NOx conversion rate than the 4AT catalyst without Cu. Cu additive did not provide an improvement in the NOx reduction performance of Ag based catalysts.
Evaluation of waste tyre granules as a filler material in polymer matrix composite materials
As the consumption of substances increases with the increasing population, waste materials also increase. The use of these waste materials in the produced composite materials has started to become widespread because it can reduce the amount of waste. In today's world, vehicle tires are one of these wastes. In this study, waste rubber rubber granules were used as filling material for the production of polymer matrix composite samples. One of the most preferred matrix materials, polyester resin, and recycled waste tire rubber granules were combined in different proportions by open molding method. The samples were experimentally characterized by tensile, impact and hardness tests. The morphological features of the samples were examined by scanning electron microscope images. The study revealed that the addition of untreated waste tire rubber granules to polyester resin reduces the tensile and yield strength values, while increasing the elongation and ductility of the material. Morphological investigations have shown that the interfacial adhesion of waste rubber granules and polyester resin is poor, and therefore, waste rubber granules must be properly processed to be used as filling material. The study showed that waste tire rubber granule/polyester composites can be used in non-structural applications with benefits such as using less fossil-sourced raw materials and contributing to the reduction of environmental pollution.
Effects of natural reinforcement agents on mechanical performance of composite materials
Composite materials are one of the prominent and popular topics of materials science in recent years. Unlike alloys, in composite materials, there is a physical interaction between at least two different materials without a chemical interaction. These materials basically consist of a matrix element which acts as a body by providing toughness and ductility to the material and holding the structure together and a reinforcement element that gives hardness and durability to the material. In recent years, different natural fibers which are renewable, recyclable and cost effective have been started to be used instead of synthetic fibers (glass, carbon etc.) which have been widely used as reinforcement element. In this study, production of polymer matrix composite materials which contains various natural fibers (jute and cotton) as reinforcement elements by vacuum assisted resin transfer molding method was achieved. Polymer composites which have five different configurations by stacking jute and cotton fabrics layer by layer were generated and the experimental results of tensile test, impact test, hardness test, water absorption capacity test, scanning electron microscope analysis were compared with pure jute and pure cotton reinforced polymer composites.
Tren aks tekerlek grubu sökme takma ekipmanı yapısal tasarımı ve prototip imalatı
Bu çalışmada raylı taşıma sistemlerinde kullanılan metro, hafif raylı ve tramvay araçlarının bakım, arıza durumlarında tekerlek bandajı değişim işleminin daha kısa sürede gerçekleştirilebilmesi, çalışanların iş güvenliğini iyileştirirken, sağlık risklerinin en aza indirilmesi hedeflenerek hidrolik tahrikli bir tren aks grubu sökme ekipmanı tasarımı ve imalatı gerçekleştirilmiştir. Tasarımını ve imalatı yapılan ekipman; ikisi hareketli üç koldan oluşan tekerlek kavraması, hareketli iki koldan oluşan aks kutusu kavrayıcı, aks tepesine basacak bir metal kafa, pres ile sökme işlemini sağlayacak bir hidrolik piston, bu pistonu çalıştıracak bir hidrolik motor ve bütün sistemi taşıyan tekerlekli bir şasiden oluşmuştur. Ekipman, sökülmesi düşünülen tekerlek grubu bileşenlerinin dikey hareketi elektrikli yükseklik ayarlı aks mengenesi ile yapılacağından, sabit yükseklikte ve insan gücü ile hareket ettirilen tekerlekli bir şasi üzerine monte edilmiştir. Sistem hareket kabiliyeti sunabilen elektrikli kumanda panelinden kontrol edilmektedir. Yapılan analizler neticesinde, aparatın planlanan fonksiyonel hareketleri gerçekleştirebildiği, aks kutusu ve tekerlek bandajı söküm işlemlerini sorunsuz yerine getirebildiği görülmüştür.
Bakır esaslı SCR katalisti üzerine selenyum içeren nano partikül ilavesinin düşük sıcaklık koşullarında NOx dönüşüm performansı üzerine etkisi
Bu çalışmada, Hidrokarbon Seçici Katalitik İndirgeme Sistemi (HC-SCR) sistemi için Cu(%3) /TiO2, Cu-Ca(%4) /TiO2, Cu-Ca-Se (%4,5) /TiO2, Cu-Ca-Se (%5)/TiO2, Cu-Ca-Se(%5,5)/TiO2 esaslı katalizör emdirme yöntemiyle sentezlenmiştir. Bu sistemde indirgeyici olarak etanol kullanılmış ve üretilen katalizörün NOx dönüşüm verimliliği üzerindeki etkisi incelenmiştir. Katalizöre ait SEM, XRD ve BET analizleri gerçekleştirilerek yapısal ve kimyasal özellikleri belirlenmiştir. SCR egzoz performans test sisteminde üretilen katalizör kullanılarak 180°C-270°C sıcaklık aralığında ve sabit alan hızında (30000h-1) deneyler yapılmıştır. Testler 2 silindirli V-tipi bir dizel motor kullanılarak sabit motor devrinde (3000 d/dk) ve 3 farklı yük (1kW, 3kW ve 5 kW) altında gerçekleştirilmiştir. Bu testlerle, SCR katalizörünün NOx emisyonu üzerindeki etkisi tespit edilmiştir. Sonuç olarak, maksimum NOX dönüşüm oranları 5 kW yükte, 270 0C sıcaklıkta, 30000 h-1 gaz saatlik alan hızında ölçülmüştür. NOX dönüşüm oranı en yüksek %94,88 olarak ölçümlenmiştir.
The properties of natural fiber reinforced hybrid composite materials as an alternative to carbon fiber composites
In recent years, the main goals of automotive manufacturers have been to lower production costs and minimize emissions from vehicles by reducing fuel consumption. In order to achieve these goals, it is essential to manufacture fossil fueled vehicles, and especially electric vehicles from lightweight, environmentally friendly, sustainable, and affordable materials. In this context, the importance given to hybrid composite materials is increasing in terms of their unique properties. In this study, carbon fiber reinforced polymer composites (CFRP) and hybrid composites of aramid and basalt fiber reinforced epoxy matrix were fabricated by using vacuum infusion method. Tensile test, hardness test, water absorption test, loss on ignition test, impact test, and Scanning Electron Microscopy (SEM) analysis were applied to CFRP composites and hybrid composite samples produced with different fiber ratios and arrays in order to observe the effect on mechanical properties. These tests were performed to evaluate the application of natural fiber reinforced hybrid composites as an alternative to CFRP used in the interior and exterior parts of vehicles. When the results were evaluated, it was determined that the fiber ratio and array significantly affected the mechanical properties of hybrid composites. Also, hybrid specimens had higher impact strength than CFRP composites. Through SEM analysis, fiber breakage, fiber shrinkage, fiber-matrix debonding and gaps were observed in the structure of hybrid composites.
Antimon ilavesinin bakır esaslı SCR katalizörü üzerindeki etkilerinin incelenmesi
Bu Çalışmada HC-SCR sistemi için Cu/TiO2, Cu-P/TiO2, Cu-P-Sb(%1)/TiO2 ve Cu-P-Sb(%2)/TiO2 kimyasal bileşenli katalizörleri emdirme yöntemi ile üretilmiştir. Üretilen katalizörlerin testleri sırasında indirgeyici madde olarak etil alkol kullanılmıştır. Farklı sıcaklık ve motor yüklerinde katalizörlerin NOX dönüşüm verimliliği incelenmiştir. Katalizörlerin yapısal ve kimyasal özelliklerini hassas bir şekilde belirlemek için SEM, XRD ve BET analizleri yapılmıştır. Test sisteminde ölçümler 180 0C ile 270 0C arasında değişen sıcaklıklarda, sabit alan hızında (30000 h-1) gerçekleştirilmiştir. Testler 3 farklı yük (1 kW, 3 kW ve 5 kW) altında sabit motor hızına (3000 d/dk) sahip, 2 silindirli V tipi dizel motor kullanılarak yapılmıştır. Bu testlerle birlikte üretilen katalizörlerin NOX emisyonu dönüştürme üzerindeki etkileri saptanmıştır. Sonuç olarak, NOX dönüşüm oranları %85,67 ile %94,89 arasında ölçülmüştür. 5 kW yükte, 270 0C sıcaklıkta, 30000 h-1 alan hızında %100 etil alkol indirgeyici madde olarak kullanıldığında NOX dönüşüm oranı %94,89 olarak ölçülmüştür.
Bir dizel motorda kullanılan su-biyodizel emülsiyon yakıtlarının performans ve emisyon karakteristikleri
Emisyon normları her geçen gün daha da katılaşmakta ve araştırmacıları ilave tedbirler alarak çevreye salınan emisyonları daha alt seviyelere çekmeye zorlamaktadır. Bu amaçla araştırmacılar tarafından kullanılan birçok yöntem mevcuttur. Bunlardan bir tanesi de su-yakıt emülsiyonlarıdır. Emülsiyon yakıt kullanımı özellikle azot oksit (NOx) ve partikül madde (PM) emisyonlarını eş zamanlı azaltmada oldukça etkin bir yöntemdir. Bu çalışmada, dizel, ayçiçek biyodizeli, saf su ve sürfaktan (Span 80 + Tween 80) kullanılarak emülsiyon yakıtlar hazırlanmıştır. Yakıtlar D (dizel), DS5 (93% dizel + 5% su + 2% sürfaktan), DS10 (88% dizel + 10% su + 2% sürfaktan), B (biyodizel), BS5 (93% biyodizel + 5% su + 2% sürfaktan), BS10 (88% biyodizel + 10% su + 2% sürfaktan) şeklindedir. Emülsiyon yakıtlar manyetik bir karıştırıcı yardımıyla oda sıcaklığında 1 saat boyunca 1500 (dev/dak) hızla karıştırılarak hazırlanmış ve yakıt özellikleri tespit edilmiştir. Son olarak da 4 zamanlı, 4 silindirli, turboşarjlı, su soğutmalı bir dizel motorunda motor performans ve emisyon testleri gerçekleştirilmiştir. Emülsiyon yakıtlar motor tork ve fren gücü değerleri ile karbon monoksit (CO) ve azot oksit (NOx) emisyonlarında azalmaya sebep olmuştur.
Effects of usage dimpled surfaces on Ahmed body jeneric model flow characteristics
Vehicle aerodynamics which directly affect fuel consumption values in vehicles, has a great importance in terms of vehicle stability, acceleration ability, vehicle noise and environmental pollution. The Ahmed car model is one of the most important generic models so this popular car model is widely used in the literature on fluid mechanics and vehicle aerodynamics studies. The simple and easy applicable shape of the Ahmed body make the model convenient in these sort of investigations. This study investigates effect of a passive drag reduction technique which it is known as dimple surface, on Ahmed car model with 35° slant angle. In order to take distinctive result, rear wake zone was selected for design optimization area. The flow control methods were applied numerically also these methods were compared with similar works. The selected passive drag reduction method was used with different model configurations to determine optimum parameters and evaluate these parameters how will effect on the vehicle drag and lift coefficients. Analyses made in this study, were calculated with 2.4 million cell number and the maximum drag value reduction was obtained as 3.5 % by using dimple surfaces. Moreover, the applicability and manufacturability factor was also evaluated in terms of implementing the dimpling modification to today's current road vehicles and in order to make this study meaningful for vehicle aerodynamics.
Comparison of the automotive bumper produced with different composite materials using the finite elements method
In recent years with the developing technology, the automotive industry and composite material production have also developed. The vehicle lightening issue, which emerged with the aim of saving fuel in the automotive sector, has increased the competition. In parallel with the developments in the automotive sector, studies have increased in the production of composite materials used to lighten vehicles. Composite materials have become widespread in the production of automotive parts with the features they offer. Composite materials are used in vehicle bumpers due to their strength and lightness. In this study, composite materials that can be used on the vehicle bumper were researched. Due to its low cost and easy processing, composite materials consisting of glass fiber and polyester are mostly used in vehicle bumpers. In the study, carbon fiber reinforcement and vinyl ester matrix, which can be an alternative to glass fiber reinforcement material and polyester matrix, were used. 6 different composite materials were created and used with 2 different reinforcement elements and 2 different matrix elements. The mechanical properties of 6 different composite materials were determined by the tensile test. The results were entered into the ANSYS program and the results of the static analysis on the buffer were compared.
İçten yanmalı motorların sürtünmeli yüzeyleri için elektrodepolama metoduyla Ni-B/TiC nanokompozit kaplamaların üretimi ve karakterizasyonu
İçten yanmalı motor parçalarının sürtünmeye maruz kalan yüzeylerine kaplama uygulanması malzemeyi aşınma ve korozyona daha dayanıklı hale getirmek için oldukça verimli bir yöntemdir. Bu çalışma kapsamında, paslanmaz çelik altlık malzeme TiC seramik nano parçacık takviyeli Ni-B alaşımı esaslı kompozit film ile elektrokimyasal depolama yöntemi ile kaplanmıştır. Kaplama işleminde Watts tipi nikel elektroliti esas alınmış, alaşım ve kompozit kaplamaların elde edilebilmesi için uygun malzemeler banyoya ilave edilmiştir. Üretilen Ni-B/TiC nanokompozit kaplamaların gelişen özellikleri paslanmaz çelik altlık, saf nikel, Ni-B alaşım ve Ni/TiC kaplamalar ile karşılaştırılarak incelenmiştir. Elektrodepolama üretim değişkenlerinden TiC parçacık banyo miktarı, bor kaynağı trimetilamin boran (TMAB) banyo miktarı ve depolama akım yoğunluğu değişiminin nanokompozit kaplamaların üzerinde etkisi incelenmiştir. Bu yeni tür malzemelerin özelliklerini belirlemek için çeşitli yöntemlerle aşınma ve korozyon davranışları ile kristal yapıları analiz edilmiş, mikrosertlik ölçümleri yapılmış, bunun yanında kaplamaların yüzey ve kesit yapıları ile kimyasal içerikleri incelenmiştir. Ayrıca kaplamaların üretildiği elektrolitlerin elektrokimyasal analizleri de yapılmıştır. Bunlara ilaveten, elde edilen kaplamaların deneysel yollarla ölçülen mikrosertlik ve kristal tane boyutu değerlerinin yapay sinir ağları (YSA) metodu ile tahmin edilebilmesi için model geliştirme çalışmaları yapılmıştır. Yapılan çalışmalar neticesinde üretilen nanokompozit kaplamaların paslanmaz çelik altlık, saf nikel, Ni-B alaşımı ve Ni/TiC kaplamalara göre mekanik ve korozyon özelliklerinde ciddi derecede iyileşme sağladığı görülmüş ve özellikle zorlu çalışma koşullarındaki makine parçaları için uygun bir seçenek olduğu kanıtlanmıştır. Anahtar kelimeler: TiC, Ni-B alaşım, elektrodepolama, aşınma, korozyon
Selenyum ilavesinin gümüş esaslı HC-SCR katalistinin özelliklerine ve NOX dönüşüm performansı üzerine etkisi
Bu çalışma hidrokarbon-seçici katalitik indirgeme sisteminin (HC-SCR) azot oksitlerin (NOx) dönüşüm oranları üzerine etkisini araştırarak bu alandaki kısıtlı literatüre katkıda bulunmayı hedeflemiştir. Bu amaçla Ag/ TiO2, Ag-Ca/TiO2, Ag-Ca-Se (%0,5) /TiO2, Ag-Ca-Se (%1) /TiO2, Ag-Ca-Se (%1,5) / TiO2 katalizörleri emdirme yöntemiyle hazırlanmıştır. Katalizör ana taşıyıcı gövdesi olarak okzalik asitle ön işleme tabi tutulmuş olan kordiyerit kullanılırken indirgeyici madde olarak da etil alkol kullanılmıştır. Elde edilen katalizörlerin SCR test düzeneğinde NOX dönüşüm performansları analiz edilmiştir. Deneyler iki silindirli, V tipi 3000 devir/dakika sabit hızında çalışan bir dizel motor kullanılarak 1kW, 3 kW, 5kW yükler altında, 180 ℃ ile 270 ℃ sıcaklık aralığında, 30000 h-1 sabit gaz saatlik alan hızında gerçekleştirilmiştir. Katalizörlere ait kimyasal ve yapısal özellikler Taramalı Elektron Mikroskobu (SEM), X-Ray Difraktometresi (XRD) ve Brunauer-Emmett-Teller (BET) analiz cihazı yardımıyla incelenmiştir. Sonuç olarak en yüksek dönüşüm oranları 5 kW yük altında, 270 ℃'de Ag-Ca-Se (%1) /TiO2 katalizöründe elde edilirken en düşük dönüşüm oranları ise 1 kW yük altında, 180 ℃ 'de Ag-Ca/TiO2 katalizörüne aittir.
Numerical examination of the impact characteristics of vehicle side door beams
In side vehicle accidents, there is very small distance between the impactor and the passenger. In such accidents, car manufacturers place impact energy absorber beams inside the door so that the passengers do not suffer from loss of life or major injures. In this study, the crashworthiness performances of impact energy absorber beams were investigated. Comparisons were made by changing the thickness, materials, angles, and cross-sections of the beams. Among the materials used (AL6061-T6 and A36 steel), AL6061-T6 material stood out with its high Specific Energy Absorption (SEA) value, low reaction force, and low permanent deformation performance. The best Velocity Absorption Time (VAT) value was obtained in the combination where the angle between the two beams defined by A36 steel was 25° degrees. It has been stated that the hexagonal cross-section door beam used is superior to the circular beam and is open to improvement.
Kalay ilavesinin gümüş esaslı HC-SCR katalistin özellikleri ve NOX dönüşüm performansı üzerine etkisi
Bu çalışmada, Hidrokarbon Seçici Katalitik İndirgeme Sistemi (HC-SCR) için AgNO3 esaslı katalistlerin geliştirilmesi ve bu katalistlerin NOx dönüşümleri üzerine etkisi araştırılmıştır. Katalizörler daldırma yöntemi ile kordiyerit malzemeden üretilmiştir. Bu amaçla 4 farklı türde, Ag/TiO2, Ag-P/TiO2, Ag-P-Sn(%1)/TiO2, Ag-P-Sn(%2)/TiO2 bazlı katalizör üretimi gerçekleştirilmiştir. Kullanılan katalizörün kimyasal ve yapısal özellikleri taramalı elektron mikroskopu (SEM), yüzey alanı ölçümü (BET) ve X-ışını difraktometresi (XRD) analiz sonuçları ile incelenmiştir. Katalizörler SCR test sisteminde 180 °C ile 270 °C arasındaki sıcaklıklarda testlere tabi tutulmuştur. Testler, 1 kW/ 3 kW/ 5 kW yükler altında sabit motor hızında (3000 devir/dakika), 2 silindirli V- Tip dizel motor kullanılarak gerçekleştirilmiştir. Sistemde etanol indirgeyici olarak kullanmıştır. Sonuç olarak, en yüksek NOX dönüşüm oranları 5 kW yükte, 270 0C sıcaklıkta, 30000 h-1 gaz saatlik alan hızında ölçülmüş ve NOx dönüşüm oranı en yüksek Ag-P-Sn(%2)/TiO2 katalizöründe %95,58 olarak elde edilmiştir.
Antimon ilavesinin gümüş esaslı SCR katalist ve NOX dönüşüm performansı üzerine etkilerinin incelenmesi
Bu çalışmada, emdirme yöntemiyle Ag/TiO2,Ag-Ca/TiO2,Ag-Ca-Sb(%1)/TiO2,Ag-Ca-Sb(%2)/TiO2,Ag-Ca-Sb(%3)/TiO2 bazlı beş adet katalizör üretilmiştir.Labaratuvar ortamında hazırlanan katalizörler HC-SCR deney düzeneğinde test edilmiştir.İndirgeyici madde olarak etanol kullanılmıştır.SEM, BET ve XRD analizleri ile testlerde kullanılan katalizörler kimyasal ve yapısal olarak incelenmiştir.HC-SCR test sisteminde gerçekleştirilen deneyler 170 °C ile 270 ºC arasındaki sıcaklıklarda gerçekleştirilmiştir.Bütün deneylerde gaz alan hızı sabit olarak 30000 h-1'de tutulmuştur. Testler herbir katalizör için 1 kW, 3 kW ve 5 kW olmak üzere üç farklı motor yükünde yapılmıştır.Testler sabit devire (3000 devir/dk) sahip, 2 silindirli V tipi,su soğutmalı dizel motor kullanılarak gerçekleştirilmiştir.Motor yüklerini ayarlayabilmek için herbiri 1 kW güce sahip ısıtıcı rezistanslar kullanılmıştır.Yapılan testler sonunda,üretilen katalizörlerin SCR sisteminde NOx dönüştürme oranı üzerindeki etkileri belirlenmiştir. Sonuç olarak, maksimum NOx dönüşüm oranı Ag-Ca-Sb(%3)/TiO2 katalistinde 5 kW yükte, 270ºC sıcaklıkta, 30000 h-1gaz alan hızında %95,88 olarak ölçülmüştür.
Characterisation of PEM fuel cell cold start process
Water droplets formed in PEM fuel cell operating conditions freeze at sub-zero temperatures and cause start-up failure. In this thesis, a quick, effective, and low energy-consuming coolant heating method has been developed by characterizing the cold start process of the PEM fuel cell. The effects of the components in the experimental setup on the cold start performance were investigated in the range of -10 and -30 ℃. The fuel cell and the external heating system were operated simultaneously and a current was drawn from the cell during the tests. Stack temperature was followed from five different symmetrical places and temperature-voltage-current profiles were plotted. In the preliminary tests at -10 ℃, ethanol as the working fluid, double-sided heating type, and full power pump operation were specified as the parameters that provide the quickest heating. The effect of the heater and pump operating durations under the same energy consumption level were compared and no significant difference was noted at this temperature. However, it is found that long pump operation at extreme conditions (-15 and -30℃ range) is essential for a successful cold start process and it provides a more homogeneous and smooth temperature transition. PEM fuel cell was operated successfully in all conditions thanks to the external heating mechanism, and the cell temperature was increased above zero in 20, 40, and 53 seconds, respectively, in cold start tests at -10, -20, and 30 ℃. Keywords: PEM fuel cell, cold start, assisted, starter technique, experimental
Aerodynamic investigation and flow control on DrivAer models using numerical (CFD) methods
Drag reduction is one of the most critical subjects for vehicles, especially considering the emerging trend of electric vehicles that have been known to drive range and efficiency issues. In this work, deflector plates were tested numerically as a passive flow control element at the upper and lower regions of the rear end of the closed body estateback, fastback, and notchback DrivAer generic car models. Plate slant angles varied to find optimum deflectors. CFD simulations have been conducted by the k-ω SST RANS turbulence model and the setup of the base model is verified with the drag force coefficient of previous experimental works. Then, parametric, genetic algorithm response surface and adjoint optimization stages were applied on the upper and lower deflectors, respectively. Consequently, simultaneous usage of these two deflectors with optimum angles resulted in reductions of CD by 17.90%, 4.82%, and 7.25% for estateback, fastback, and notchback respectively. However, detailed qualitative analysis is shown that upper and lower deflectors have different drag reduction mechanisms at the wake. The upper deflector reduces wake statistics and attains pressure recovery at the back surface by improved downwash for all models. On the other hand, the lower deflector restricts airflow beneath the car for the estateback. Hereby, this provides pressure recovery at the slanted diffuser section by blocking its functionality while the restricted airflow is deflected to the upperbody and results in pressure recovery at the rear surface, too by improved upwash, although it increases the wake region. For the fastback model, the lower deflector provides flow control by improving the upwash, while for the notchback model, it provides a flow control by preventing the flow interaction between the downwash and the upwash.
Use of fusel oil as a reductant agent in a SCR system at low temperatures
Within the study, the efficiency of NOₓ transformation rates at low temperatures was examined by using fusel oil for reducing and a catalyst made of Mo-Cu-Ag/TiO₂ in the HC-SCR system. The properties of the catalyst were determined by BET, SEM, FTIR and XRD analysis. The experiments were conducted in the range of 200-300 °C, at 3 different space velocities (30000 h-1,40000 h-1and 50000 h-1) and under 5 various motor loads (1, 2, 3, 4 and 5 KW). A 2-cylinder V-type diesel engine were used during the experiments. As the outcome of the performance tests, the maximum NOₓ transformation efficiencies were obtained at 290 °C, the highest test temperature, at all space velocity values and engine loads. The highest NOₓ conversion rate among all tests was obtained as 85.94% at 290 °C at 1 kW at 30000 h-1. Increasing the exhaust gas temperature from 200 to 290℃ had a positive effect on the NOₓ transformation efficiency. Keywords: SCR, Exhaust Emissions, NOₓ, Reductants, Fusel oil
Evaluation of mechanical properties of 500 hbw armor sheet after welding with different welding wires and preheating temperatures
Armor steels play a crucial role in providing protection against ballistic threats in various applications, including military vehicles, body armors, and structural components. Welding is a widely employed joining technique for armor steels, allowing the fabrication of complex structures with enhanced mechanical properties. However, the welding process can introduce significant changes in the microstructure and mechanical properties of the base material, necessitating a thorough understanding of the effects of welding parameters. This thesis aims to investigate the influence of preheating temperature and welding wire type on the mechanical properties of high-hardness armor (HHA) steels, specifically focusing on the HBW 500 armor plate. The study explores the relationship between preheating temperature, welding wire type, and key mechanical properties such as toughness, hardness, and tensile strength through a comprehensive experimental analysis. As a result, this study has taken significant steps in enhancing our understanding of how preheating temperature and filler wire type affect the mechanical properties of high-strength armor steel. The findings have demonstrated the importance of carefully controlling the preheating temperature and selecting an appropriate filler wire type based on the desired mechanical properties in welded armor structures. The findings from this research will contribute to the optimization of welding procedures for armor steels, enhancing their performance and reliability in demanding applications. Keywords: Armor, Mechanical Properties, Preheat, Welding, Welding wire.
Motosiklet tipine göre en ideal motosikletin belirlenmesi
Son yıllarda ülkemizde motosikletler daha önceki zamanlara göre daha çok tercih edilmektedir. Bunun sebepleri ise nüfustaki kalabalıklaşma, artan enflasyon oranı, diğer taşıtlara göre yakıt tasarrufu ve trafik ile park sorunu gibi etmenlerdir. Bu çalışmada motosiklet kullanıcılarına yönelik sorular sorulmuş olup elde edilen veriler doğrultusunda kullanıcıların hangi tür motosikleti alma konusunda daha kolay karar verebilmeleri amaçlanmıştır. Buna ek olarak çok amaçlı karar verme yöntemleri kullanılarak elde edilen bulgular ile birlikte kullanım amacına göre en ideal motosiklet tipleri belirlenmiştir.
Bir ticari araçta sonlu elemanlar metodu
Treyler bir diğer adıyla yarı römork, dünyada taşımacılık sektöründe kritik önem arz etmektedir. Türkiye'de ekonomik olması, alternatif kullanım şekilleri ve yoğun servis hizmetlerinin bulunması ile yarı römorklar daha çok kullanılmaktadır. Yarı römork taşıtlar arasında da en çok tercih edilen damperli yarı römork araçların ağırlığının çoğunluğunu şasi oluşturmaktadır. Kullanıcılar tarafından çok çeşitli yüklerin yüklendiği treylerin şasisine dinamik ve statik birçok kuvvet uygulanmaktadır. Üreticilerimiz de bu sebeplerden öncelikli çalışma alanlarını şasi üzerinde yoğunlaştırmışlardır. Bir damperli yarı römork şasisinin enine ebatları azaltılarak tasarlanan bu çalışmada statik analizler ışığında yeni tasarım ile eskisi karşılaştırılmaktadır. Modellenen yeni dar yapıda tasarım, Alman Standartları Enstitüsü standartlarına göre aks yay merkezleri arası mesafeler temelinde şekillendirilmiştir. Bu çalışmanın ana hedefi, dayanımı azaltılmadan dar formda, hafifletilmiş, sağlayacağı yakıt tasarrufuyla çevre dostu yeni bir yarı römork tasarlamaktır. Sonuç olarak; incelenen analiz çalışmaları ve incelemeler, dar formda tasarlanan yeni yarı römorkun % 7 oranında hafifletilerek yakıt tasarrufu ve emisyon azaltımı ile çevreci bir treyler tasarımına ulaşılabileceğini göstermektedir.
Weight reduction on the semi trailer chassis by using ultra high strength steel (UHSS) instead of metal material
With the publication of the Paris Agreement, manufacturers producing O3 and O4 category trailers for the logistics sector have also accelerated their work within the framework of green transformation. With this agreement, it is aimed to reduce carbon emissions by 30% in heavy-duty vehicles by 2030. In recent years, commercial vehicles manufacturer especially heavy duty vehicles manufacturer target a produce light-weight vehicles in order to increase payload and decrease fuel consumption and emissions Because of the transport high payload, manufacturer always use S355 with high thickness steel to reach high strength. However by using ultra high strength steel, manufacturer can reach high strength. In this study, the mechanical properties, stresses, and deformations of ultra-high-strength steel and S355 steel in the semi-trailer chassis named SBPR27, referred to as the modular chassis by Koluman Otomotiv Endüstri A.Ş, were compared under a 30-ton load using the ANSYS software.. According to the results obtained, the analysis results of S355 and UHSS steel were compared under the same boundary conditions and when UHSS steel is used as chassis material; it is aimed to save total weight by reducing the cross-sectional thickness of the longitudinal supports. According to the new weight result obtained, the analysis was run in the VECTO Trailer application and the carbon emission rate and fuel consumption value were compared. According to these results, a 9% reduction in chassis weight of 182 kg led to a fuel saving of 2.9% per 100 km and a reduction in carbon emissions of 3% per km.
Basitleştirilmiş treyler-çekici kamyon geometrisinde tasarım değişikliklerinin aerodinamik direnç katsayısına etkisi
Taşımacılık endüstrisinde enerji verimliliği ve çevresel sürdürülebilirlik, günümüzde giderek artan öneme sahip temel konulardır. Bu bağlamda, taşımacılık araçlarının aerodinamik tasarımı, hem yakıt tüketimini azaltmak hem de karbondioksit emisyonlarını düşürmek için etkili bir strateji olarak kabul edilmektedir. Özellikle, kamyonların aerodinamik performansının iyileştirilmesi, taşımacılık endüstrisinde önemli bir potansiyele sahiptir. Çalışmada, taşımacılık endüstrisinde önemli bir konu olan basitleştirilmiş treyler-çekici geometrisi tasarımı değişikliklerinin aerodinamik direnç katsayısına etkilerini incelenmiştir. Araştırma, Ansys 2023 R2 yazılımının kullanımıyla gerçekleştirilen kapsamlı bilgisayar destekli tasarım ve analizleri üzerinden ilerlemektedir. Bu Çalışma, çekici deflektör ve treyler yarım gözyaşı modeli kullanımının, aerodinamik performans üzerindeki etkilerini anlamak amacıyla iki farklı model (Model-A ve Model-B) kullanılarak, her biri için 11 farklı Varyant modelin hesaplamalı akışkanlar dinamiği analizlerini içermektedir.Model-A çekici üst kenarı keskin köşeli model, Model-B ise çekici üst kenarı yuvarlatılmış model olarak tanımlanmıştır. Ansys Fluent yazılımı kullanılarak her bir varyant için aerodinamik direnç katsayıları hesaplanmıştır. Oluşturulan analiz modelleri için rüzgar tüneli geometrisi kurgulanmış olup Reynolds sayısı 0.51x10^6 olarak hesaplanmıştır ve yapılan 22 farklı analiz çalışmasında aynı sınır şartları uygulanmıştır. Analiz sonuçlarına göre, Model-A Varyant 1 için Cd değeri 0.709 olarak ölçülmüştür, en fazla geometrik düzenlemenin olduğu Varyant 11 için ise bu değer 0.380'dir. Bu durumda direnç katsayısının değişim oranı %46.40 olarak hesaplanmıştır. Model-B Varyant-1 için ise Cd değeri 0.711 olarak belirlenmiştir, en fazla geometrik düzenlemenin olduğu Varyant 11 için ise de bu değer 0.351'dir. Buna göre direnç katsayısının değişim oranı %56.53 olarak hesaplanmıştır.