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Organik Rankine Çevrimi (ORÇ), termal enerjiyi elektrik enerjisine dönüştüren, yüksek oranda erişilebilir, yaygın olarak kullanılan bir enerji üretim şeklidir. ORÇ’de, türbin jeneratörü termal enerjiyi önce mekanik enerjiye sonra da jeneratör aracılığıyla elektrik enerjisine dönüştürür. Sıradan buhar türbinleri ile karşılaştırıldığında; ORÇ sisteminde dolaşan organik akışkanlar su buharının yerini alır, ancak sudan daha yüksek moleküler ağırlıklı organik sıvıları buharlaştırarak sirkülasyon hızını düşürür ve metal parçalar üzerindeki basıncı azaltır. ORÇ’nin ideal akışkanları genellikle sıfır ...Daha fazlası
In this study, the effect of evaporator pinch point temperature difference (∆TPP,e) value in Organic Rankine Cycle (ORC) on system performance was determined. Under different applications of ORC, optimum ∆TPP,e value has been determined in ORC systems designed with different heat source temperatures. By changing the ∆TPP,e value, the heat input provided to the system, the mass flow of organic fluid, the evaporation pressure and the enthalpy drop in the turbine are affected. In thermodynamic optimization, the objective function is determined as turbine power maximization. Genetic algorithm opti ...Daha fazlası
Hot tearing is one of the most interesting defects that can be found during casting of aluminium alloys. The definition of this defects has some uncertainties such as “it does not always appear under apparently identical conditions” or “the defect is highly specific to certain alloys”. There are several works in the literature on the modelling and analytical approaches. However, the experimental findings have not been satisfactory. In this work, A356, A380 and A413 alloys were cast in two different moulds to investigate the hot tearing tendency with regard to the melt quality. It was found tha ...Daha fazlası
In order to simulate the wear behavior of materials subjected to solid particle erosion due to high temperature as well as velocity effect in operating conditions such as power plants and jet engines, ASTM G76 standard is not sufficient and test rig compliant with ASTM G211-14 standard must be put forward. In this context, a test rig, alternative to existing systems where solid particle erosion wear experiments can be performed in compliance with high temperature (~ 700 °C) and particle impact velocity (~ 150 m/s) conditions, has been designed and produced. In order to ensure the widespread us ...Daha fazlası
GÜLEÇ, Ali | ACAR, Mehmet Ali | AYDIN, Bahattin Kerem | DEMİR, Teyfik | ÖZKAYA, Mustafa
Supracondylar humerus fractures are common fractures around the elbow. Open fractures, comminuted metaphyseal fractures and also fractures with bone loss may need to be treated with external fixators. The aim of this study is to compare two different external fixators, tubular external fixators and polymethyl methacrylate with K wires external fixators, with regard to stiffness and stability for metaphyseal-diaphyseal osteotomies of distal humerus close to the joint. Six matched pairs (24 specimens) of second-generation sawbone humerus were prepared in a standard fashion to create a metaphysea ...Daha fazlası
Previously, Preheating has been established in micro-nozzles to increase the specific impulse of thrusters and increase thrust level. However, heating may cause higher viscous losses in micro-nozzles working at low Reynolds numbers. In this work, heating is combined with gas expansion by using heated walls for convergent-divergent micro-nozzle. The flow in 2D micro-nozzle with heat generation inside the side-walls has been numerically simulated and analyzed. A wide range of low Reynolds numbers flow is tested to investigate the effect of flow parameters. A range of diverse amounts of heat flux ...Daha fazlası
In this study, parametric optimization and sensitivity analysis of performance parameters were performed for the Organic Rankine Cycle (ORC) system at 120 °C heat source temperature. R1234ze, which is called the new-generation fluid, was used in the ORC design. Performance parameters have been selected considering Energy, Exergy, Economy (Turbine performance) and Environmental (Thermodynamic sustainability indices) factors. Six performance indices used in the orthogonal design with Taguchi-ANOVA. These are; thermal efficiency, turbine power, exergy efficiency, total irreversibility, Volume Flo ...Daha fazlası
ATA, Sadık | AKSOY, Mehmet | ŞAHİN, Remzi | KAHRAMAN, Ali
Organik Rankine Çevrimi (ORÇ), düşük sıcaklık aralığında su yerine organik akışkanın kullanıldığı bir elektrik üretim sistemidir. ORÇ, elektrik üretmek için atık ısıyı değerlendirmek amacıyla santrallerde kullanılmaktadır. Bu çalışmada kuru ve izantropik akışkanlar kullanılarak ORÇ modelinin çevresel ve termodinamik performans karşılaştırmaları yapılmıştır. Jeotermal uygulamaları kapsamında ısı kaynağı sıcaklığı 110 °C olarak belirlenmiştir. Buharlaşma sıcaklığının 65-100 °C arasında değişmesinin sistem performansı üzerindeki etkisi belirlenmiştir. Performans parametreleri olarak pompa işi, tü ...Daha fazlası
HAMEED, Amar Hasan | MOHAMMED, Ahmed Abdullah | FADHIL, Obaid
Cooling heat flux effect in both primary and secondary cooling zone has been studied in semi-continuous casting of copper billet. Sufficient cooling is essential to reduce casting defects and to get high productivity, however low rate of solidification is aimed in order to get coarser grain size and softer metal for less losses in extrusion. A three-dimensional numerical model has been developed including solidification behavior of copper through mushy zone. At steady state and constant casting speed, solid shell thickness is monitored during the reduction of cooling rate at mould region to av ...Daha fazlası
BAĞCI, Mehmet | ŞÜKÜR, Emine Feyza | DEMİRCİ, Musa | KAYBAL, Halil Burak
During erosion tests of glass fibre/epoxy nanocomposites, an incubation period emerged because of the embedding of abrasive particles into the target material. In this study, the effect of this period on solid particle erosion behaviour was investigated for glass fibre/epoxy composites with the addition of nanoclay. The surface erosion characteristics of the composites were obtained by solid particle erosion tests using angular alumina particles with a size on the order of 400 μm as the erodent. The tests were conducted using impact velocities of ~23 or ~34 m/s and impingement angles of 30°, 6 ...Daha fazlası
ÇETİN, Remzi | ULUDAĞ, Muhammet | KOÇABAŞ, Mustafa | DIŞPINAR, Derya | CANSEVER, Nurhan
In the present study, the corrosion behaviour of A356 (Al-7Si-0.3Mg) alloy in 3.5% NaCl solution has been evaluated using cyclic/potentiodynamic polarization tests. The alloy was provided in the unmodified form and it was then modified with AlTi5B1 for grain refinement and with AlSr15 for Si modifications. These modifications yield to better mechanical properties. Tensile tests were performed. In addition, bifilm index and SDAS values were calculated and microstructure of the samples was investigated. As a result of the corrosion test, the Ecorr values for all conditions were determined approx ...Daha fazlası
ÇETİN, Remzi | ULUDAĞ, Muhammet | DIŞPINAR, Derya | TİRYAKİOĞLU, Murat
The effects of degassing, holding time and melt additions (Sr, Sr + Ti, Ti, B and B + Sr) on the quality of A356 melts were examined. A total of 120 reduced pressure test samples were collected. Pores in these samples were analyzed via digital image processing to determine the number density of pores as well as the statistical distribution of their sizes. Results showed that in all cases, degassing with argon reduced the number of defects regardless of the additions made to the melts. Moreover, all additions were found to degrade melt quality. The lowest number density of pores in all melts wa ...Daha fazlası
6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve cerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.