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Öğe A comparative experimental performance evaluation of solar air collector having absorber plate with convex oval-trench dimple(Springer Science and Business Media Deutschland GmbH, 2023) Abuşka, Mesut; Şefik, Seyfi; Özdilli, ÖzgürThe purpose of this research is to examine how convex oval-trench dimples placed staggered on a solar air collector's absorber improved vortex heat transfer. At air mass flow rates of 0.013, 0.027, and 0.036 kg/s, convex oval-trench dimple absorbers with relative roughness heights, e/D=0.2 and e/D=0.4, as well as a flat plate absorber, were evaluated for back-pass and frontpass applications. The oval-trench dimpled absorber plates in the back-pass and front-pass achieved the maximum energy efficiency of 37.5% and 50.6%, respectively, with e/D=0.4 and 0.036 kg/s. The increase in the number of Nu in e/D=0.4 was 26% and 31% more than that of the flat plate for the examined parameter ranges of back-pass and front-pass, respectively. (e/D=0.4)/(flat plate) and (e/D=0.4)/(e/D=0.2) increased by an average of 28% and 24% in back-pass for (Nuotd /Nu0)/(fotd / f0), respectively. In front-pass, (e/D=0.4)/(flat plate) and (e/D=0.4)/(e/D=0.2) improved by 35% and 25%, respectively. The collector with a relative roughness height of 0.4 has the optimal structure for this examination of collectors with an ovaltrench dimple. The results indicated that collectors with convex oval-trench dimples outperform flat plates in terms of surface area expansion and turbulence generation, which boosts thermal efficiency substantially. In addition, when the experiment results were compared, the front-pass implementation outperformed the back-pass approach. As a result, thermal systems may benefit from utilizing the convex oval-trench dimple.Öğe An Investigation of the Effects of a Sheet Material Type and Thickness Selection on Formability in the Production of the Engine Oil Pan with the Deep Drawing Method(2020) Özdilli, ÖzgürIn internal combustion engines, in a way integrated under the engine block, the oil pan is used to store the engine oil, to separate foreign substances in the oil coming from the engine block, to lubricate the moving parts, to help the engine cooling system. In this study, by using different materials such as DC06 (IF), AISI 304, Al6082, and DC01 and selecting different thicknesses such as 1.5 mm and 2 mm, the deep drawing method was applied to them, and their formability behaviors with deep drawing were investigated. The effects of the sheet material type and thickness parameters on the tensile force and wall thickness variation on a sample engine oil pan formed by deep drawing were determined. Different parameters were determined for the sample engine oil pan. According to the analysis results, it was detected that the wall thicknesses of the sensitive points were determined to decrease by 0.86 mm, 0.62 mm, and 0.37 mm, respectively, for deep drawn samples with a 1.5 mm thickness (AISI 304, DC06, DC01), but tearing occurred in the Al6082 material. On the other hand, when the sheet material thickness was increased to 2 mm, it was observed that the thickness change rates decreased by 13% in DC06, 0.7% in AISI 304, 33% in Al 6082, and 4% in the DC01 material type in comparison with the initial sheet thickness of 1.5 mm. The results of the analysis obtained in this study demonstrated that these four materials had superiorities over each other, that the thickness of the material was an essential criterion in deep drawing, and that the use of a 2 mm thick AISI 304 material among the selected materials in the production of the engine oil pan was more suitable.Öğe Deep drawing of polymer coated metal sheets(Korean Society of Mechanical Engineers, 2019) Erdin, Muhammed Emin; Özdilli, ÖzgürIn the present study, the deep drawing of polymer coated metallic sheets were experimentally investigated to reduce friction and increase manufacturing efficiency without using a lubricant. Coating of metal sheets with a polymer material before the deep drawing process provides numerous other advantages such as long service life, decorative appearance, corrosion protection, prevention of excessive abrasion. In the experiments, deep drawing ratio, blank holder pressure, and punch speed parameters were varied at various intervals and the obtained values were evaluated via graphs. Experiments of the uncoated metal sheets were conducted as well as the coated ones to compare the results. Results of this study showed that the polymer coating improved the surface quality of the test specimens. As a result of this improvement; the average molding forces decreased, obtained deep drawing ratios increased and defects such as tearing and wrinkling were alleviated by coating metal sheets with polymer material compared to uncoated sheets. © 2019, KSME & Springer.Öğe Experimental and numerical analysis of the splay impact on the performance of splayed cross-cut fin heat sink(Elsevier France-Editions Scientifiques Medicales Elsevier, 2021) Şevik, Seyfi; Özdilli, ÖzgürIn this study, splayed effects on the thermal performance of standard cross-cut heat sink (S-CCHS), fixed-array splayed (FAS-CCHS), and full splayed (FS-CCHS) under natural and forced conditions are studied experimentally and numerically. For this purpose, variable parameters such as splayed ratio, different powers of LEDs, natural and forced conditions, and blowing direction have been studied. The results showed that the thermal performance is significantly impacted by the spread position of the fins, blowing direction, natural and forced conditions of the CCHS but is not very sensitive to LEDs' powers. The results show that the full splayed heat sink occupies the highest physical volume, thus, provides the highest thermal performance by efficiently dissipating heat compared to other heat sinks designs. Experimental and numerical results show that the full splayed effect provides 5.46% and 2.59% lower junction temperature in natural and forced, respectively. Also, FS-CCHS achieved a 7.09% reduction in thermal resistance at natural convection 3 W and a 2.62% reduction at 10 W, respectively, compared to the flat fins and the fixed array wide fin heat sink. For this study, while the most suitable flow direction was determined as push, the most suitable orientation was found to be upward, and the splayed impact was also beneficial.Öğe Experimental and numerical investigation on the thermal performance of linear LED housings under forced convection(Pergamon-Elsevier Science Ltd, 2021) Abuşka, Mesut; Şevik, Seyfi; Özdilli, ÖzgürThis study aims to experimentally and numerically test the thermal performances of three different linear housings (Model 1-without fin, Model 2-with inner fin, and Model 3-with inner and outer fin) with medium power light-emitting diode (LED) arrays at 30 degrees C and 40 degrees C ambient temperatures under forced convection for 25 W and 35 W. Although the mass of Model-3 was reduced by 54.2% and 34.67% compared to Model-1 and Model-2, its surface area was increased by 46.3% and 9.11%, resulting in an improvement in junction temperature (T-j) up to 4.4 degrees C and 7.75 degrees C, respectively. Thermal resistance (Rth) for Model-3 is approximately 1.38-3.1% and 7.85-9.72% smaller than that of Model-1 for 25 W at ambient air temperature (T-aa = 30 degrees C and T-aa = 40 degrees C), respectively. The Rth for Model-3 is approximately 1.39-2.6% and 8.65-6.07% smaller than that of Model-1 for 35 W at the same T-aa, respectively. The Model-3 offers lower junction temperature, lower cost, and safe operating temperature range by inner and outer fins compared to the others. The results demonstrated that all of the temperatures reduced with the increase in air mass flow rate; however, it was found that as the LED power and ambient temperature increased, the junction temperature increased. Experiment and simulation results show that adding a fan to the luminaire significantly lowers the LED junction temperature, in which case it provides a safe operating range and protects the luminaire against thermal shocks. The forced application allows using of comparatively smaller housing as it provides a lower junction temperature.Öğe Polimer kaplı metal sacların derin çekme davranışının incelenmesi(Hitit Üniversitesi Fen Bilimleri Enstitüsü, 2018) Özdilli, Özgür; Erdin, Muhammed Eminİmalatta derin çekme işlemi sac metallere üç boyutlu şekil vermek için otomobil ve makinaların gövde sacları, beyaz eşyalar, jantlar, mutfak evyeleri, mutfak eşyaları, medikal kaplar ve içecek kutuları başta olmak üzere pek çok üründe yaygın kullanılan bir yöntemdir. Derin çekme işlemi büyük miktarda plastik deformasyonun gerçekleştiği; malzeme anizotropisi, parça geometrisi, malzemenin kimyasal bileşimi, ortam koşulları, zımba hızı ve etkin basınç başta olmak üzere pek çok parametrenin etkin olduğu ve matematiksel analizin son derece zor olduğu bir imalat yöntemidir. Yırtılma, kırışma, çizilme ve kulaklanma gibi hasarlar oluşmadan en yüksek derin çekme oranını yakalayabilmek için, baskı plakası basıncı ve sürtünme değerlerinin belirlenmesi çok önemlidir. Bu çalışmada sürtünmeyi azaltmak ve imalat verimliliğini arttırmak için polimer kaplamalı çelik sacların derin çekme işlemi deneysel olarak incelenmiştir. Deneylerde çekme oranı, baskı plakası basıncı ve çekme hızı parametreleri çeşitli aralıklarda değiştirilmiş ve elde edilen değerler grafikler yardımıyla değerlendirilmiştir. Derin çekme sırasında yukarıda belirtilen kusurları azaltmak ve ürün kalitesini yükseltmek amacıyla çeşitli yağlayıcılar kullanılmaktadır. Buna rağmen yüzeylerde plastik şekillendirme sonucunda yanma ve çizilmeler oluşmaktadır. Ayrıca derin çekilmiş bir ürüne imalat sonrası, her türlü kaplama ya da boyanın uygulanması mümkün olmamaktadır. Derin çekme işlemi öncesinde metal sacların polimer esaslı bir malzeme ile kaplanması; uzun ömür, dekoratif görünüm, korozyon direnci, aşırı aşınmanın engellenmesi, derin çekme esnasında sürtünmenin ve yağlama ihtiyacının azalması, bazı imalat yöntemlerinde şekillendirme sonrası boyama hattı gereksinimini ortadan kaldırması gibi avantajlar sağlamaktadır.Öğe Thermal performance analysis of a novel linear LED housing with inner and outer fins(Pergamon-Elsevier Science Ltd, 2020) Şevik, Seyfi; Abuşka, Mesut; Özdilli, ÖzgürThere is an inverse relationship between the junction temperature of the light-emitting diode (LED) and its lifetime therefore, it is significant to operate it at low junction temperature. In this study, three different natural convection linear housing models were developed to cool mid-powered LED arrays, focusing on basic parameters such as fin structure, surface area, and wall thickness in the design of the models and thermal performance has been tested numerically and experimentally. The performance tests were carried out at five different ambient temperatures, 20, 25, 30, 35, and 40 degrees C. Compared to Model-1 (standard housing without fin) and Model-2 (thin housing with inner fin), the cooling effect of Model-3 (thin housing with inner + outer fin) is remarkably high, and this effect was more evident with the increase in ambient temperature. This impact has been achieved by increasing the surface area of Model-3 by almost 50%, although its mass has decreased more than twice. The maximum junction temperatures of Model-3 were approximately 2 degrees C lower than Model-1 and 5 degrees C lower than Model-2 in all experiments, with the presence of fins and the development of geometry. When the maximum allowable temperature rise is 94.68-101.25 degrees C and the 35 watts dissipated in the package, the average thermal resistances were found to be 1.12-1.38 degrees C/W. It is thought that these new-generation LED-based linear designs can be used to illuminate the work areas and they can replace compact lamp-based luminaires that work with direct and indirect lighting principles.
