TR-Dizin İndeksli Yayınlar
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14901/697
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Browsing TR-Dizin İndeksli Yayınlar by Author "Afshari, Faraz"
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Article The Effects of Circular Inserts on the Thermal and Flow Characteristics in a Horizontal Pipe Exchanger: A Numerical Investigation(2023) Yeşilyurt, Muhammet Kaan; Afshari, Faraz; Adıgüzel, Nesrin; Yıldırım, Orhan; Çomaklı, ÖmerThe aim of the present study was to numerically investigate the effects of circular inserts placed inside a circular tube in order to evaluate the heat transfer characteristics under different operating conditions. Computational Fluid Dynamics methods were used to solve the model, which is a heat pipe with an outer diameter of 21 mm equipped with circular inserts with a distance of 20 cm. Different mass flow rates of the heat transfer fluid, including 25, 50, 75, 100, and 125 g/s were examined, and the thermal behavior of the turbulators and the flow structure were investigated. R19.0 version of ANSYS Fluent software was used as the CFD program to obtain the desired results and contours. From the results, it was found that circular inserts can be used in heat pipes to produce vortices and thus improve the heat transfer.Article Citation - WoS: 2Empirical Investigation of Small-Scale Aluminium Wool Packed Solar Air Heater Made with Waste Material(Gazi Univ, 2021) Khanlari, Ataollah; Tuncer, Azim Dogus; Sirin, Ceylin; Afshari, Faraz; Gungor, AfsinWaste production is an important problem for the developing world and globalization. The waste materials can be reused through recycling process and its environmental effects can be minimized. Utilizing renewable energy sources at the maximum level is also an important issue for a sustainable development in future as well as waste management. In this study, small-scale solar air heating systems were produced from waste materials to analyze the usability of waste material in renewable energy systems. Scrap metal elbows were used in the production of heaters. The first solar heater is hollow (SH) and the second one was modified by filling it with aluminum wool (SHAW). Both heaters were tested simultaneously at different flow rates (0.014, 0.010 and 0.006 kg/s). According to the experimental results, the thermal efficiency values for SH and SHAW were found in the range of 33.63-42.90% and 42.69-56.98%, respectively. In addition, it was observed that a low cost modification such as using aluminum wool can significantly increase thermal performance of the solar heating system.Article Citation - WoS: 1Long-Term Stability of Novel Surface-Modified Fe3O4 Nanoparticles Used for Preparing Water Based Nanofluids(Gazi Univ, 2024) Muratcobanoglu, Burak; Mandev, Emre; Sahin, Bayram; Manay, Eyuphan; Rahimpour, Shabnam; Teimuri-Mofrad, Reza; Afshari, FarazNanofluids are produced by suspending different solid nano-size materials (metal and nonmetal) in a base liquid and are often used in energy systems to increase thermal performance and heat transfer rate. The main problem observed in nanofluids used in heat transfer applications is their instability. Researchers have developed and proposed some solutions to obtain stable nanofluids. One of the most important solutions, is the nanoparticles surface modification method. In this work, Fe3O4 nanoparticles were subjected to chemical processes and their surfaces were modified. Three different modified nanoparticles were synthesized, which are Fe3O4@SiO2@Si(CH2)(3)-IM [Cl], Fe3O4@Si(CH2)(3)-IM [Cl], and Fe3O4@SiO2&Si(CH2)(3)-IM [Cl] nanoparticles. The nanofluids were prepared in 0.2% Vol. fraction by using the produced particles in base fluid which was distilled water, and stability of nanofluids were observed for 3 months. Nanofluids were subjected to ultrasonication for 3.5 h to obtain homogeneous nanofluid. Not modified water-based Fe3O4 nanofluid completely collapsed in approximately 1 week. In modified nanofluids, although sedimentation occurred, it was observed that a certain amount of the particles remained suspended even after 3 months. The most important analyses in this study are Scanning Electron Microscope, X-Ray Diffraction, and Transmission Electron Microscope.Article Lpg Yakıt Kullanarak Farklı Kombilerin Çevresel Etkilerinin Araştırılması(2019) Khanları, Ataollah; Varıyenlı, Halıl Ibrahım; Afshari, FarazBinaların ısıtılması ve sıcak su temini genellikle kombiler yardımıyla yapılmaktadır. Kombilerin farklı tipleri mevcuttur. Son yıllarda konvansiyonel kombilere göre yüksek verimli yoğuşmalı tip kombiler piyasaya sürülmüştür. Bu çalışmada, kombi tipinin kirletici gaz emisyonu üzerindeki etkisi deneysel olarak incelenmiştir. Deneylerde yoğuşmalı, tam yoğuşmalı ve konvansiyonel tip kombi olarak üç farklı kombi kullanılmıştır. Ayrıca, sıcaklığın etkisini belirlemek için deneyler çeşitli sıcak su sıcaklıklarında gerçekleştirilmiştir. Elde edilen sonuçlara göre, yoğuşmalı ve tam yoğuşmalı kombiler tüm sıcaklıklarda NO, NOx ve SO2, gaz emisyonlarını önemli ölçüde azaltmıştır.Article
