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Öğe An experimental investigation of the effect of thermophysical properties on time lag and decrement factor for building elements(Gazi University, 2020-06-01) Oktay, Hasan; Yumrutaş, Recep; Argunhan, ZekiThe time lag (TL) and decrement factor (DF) are essential for the heat storage capabilities of building elements, which strictly depend on the thermophysical properties of the elements. Many investigations are presented in literature arguing to find the influence of each thermophysical property on TL and DF by keeping the other properties constant. This study aims to investigate the effect of each property on TL and DF, utilizing relationships between the measurement values of the thermophysical properties of wall materials. Therefore, first, 132 new concrete wall samples were produced, and their thermophysical properties were tested. Secondly, TL and DF values for each building element are computed from the solution of the problem by Complex Finite Fourier Transform (CFFT) technique. Finally, a multivariate regression analysis has been performed, and the variations of each thermophysical property versus TL and DF are presented, and also the findings are compared with literature. The results show that each property alone (keeping the other properties constant) is not adequate to identify the thermal inertia and thermal performance of a wall element. Besides, 87.3 % decrease in thermal diffusivity corresponds to 6.03 h increase in the value of TL and 88.8 % decrease in value of DF; respectively, for W1 wall assembly.Öğe RCCI yanmalı motorda aspir biyodizeli karışımları ve benzin kullanımının orta yüklerde performans ve emisyon etkilerinin incelenmesi(Fırat Akademi A.Ş, 2017) Aydın, Hüseyin; Işık, Mehmet Zerrakki; Oktay, HasanDizel bir jeneratörde RCCI uygulamasının performans ve emisyonlar üzerine etkileri, yüksek reaktviteli (birincil yakıt) yakıt olarak aspir yağı biyodizeli ve dizel karışımları, düşük reaktiviteli yakıt olarak benzin kullanımıyla incelenmiştir. RCCI uygulaması ikincil bir yakıt enjeksiyon sisteminin emme manifolduyla irtibatlandırılmasıyla sağlanmıştır. Benzin RCCI uygulama oranı motorun toplam kütlesel yakıt tüketiminin %40'u ve %60'si oranında olup, PFI olarak önceden karıştırılmıştır. Testler dizel-jeneratör grubunun tam gücünün %50’ine karşılık gelen ve orta yükleme sayılacak sabit bir 7.2kW motor gücü ve 1500devir/dakikalık bir motor devri gerçekleştirildi. Dizel ile biyodizel karışımının amacı, yanmanın başlamasını kolaylaştırmak için birincil yakıtın reaktivitesini arttırmaktır. Motor alanındaki çalışmaların için en önemli performans ve emisyon parametreleri derinlemesine incelenmiş ve sonuçlar sunulmuştur. RCCI uygulamasında toplam yakıt tüketimi artmış, NOx emisyonları önemli ölçüde azalırken, CO ve HC emisyonları düşük oranda artmıştır.Öğe Konsantrik tip bir ısı değiştiricisinde türbülatörlerin etkisinin sayısal incelenmesi(Muğla Sıtkı Koçman Üniversitesi, 2015) Oktay, Hasan; Budak Ziyadanoğulları, Neşe; Yücel, Halit Lutfi; Işık, Mehmet ZerrakkiÖğe Çok katmanlı duvar ve çatı tiplerinin ısıl ve fiziksel özelliklerinin dinamik ısıl karakterlerine olan etkisinin incelenmesi(Muğla Sıtkı Koçman Üniversitesi, 2015) Oktay, Hasan; Budak Ziyadanoğulları, Neşe; Argunhan, Zeki; Yumrutaş, Recep; Işık, Mehmet ZerrakkiÖğe Artificial neural network approach for theprediction of thermal ınsulation properties of lightweight building materials for energy efficient buildings(İnönü Üniversitesi, 2016) Oktay, Hasan; Polat, Süleyman; Fidan, ŞehmusÖğe Aspir ve kanola biyodizeli kullanımının egzoz emisyonu ve motor performansına etkilerinin incelenmesi(Küresel Mühendislik Çalışmaları Dergisi, 2016-04-01) Aydın, Hüseyin; Işık, Mehmet Zerrakki; Ziyadanoğulları Budak, Neşe; Oktay, Hasan; Bayındır, Hasan; Yücel, Halit LutfiBiodiesel fuel, which can be produced from crude or waste vegetable oil, is an important alternative renewable fuel for diesel engines. Particularly the use of vegetable oils for diesel engines has found an important place in several surveys. Biodiesel can be used alone, or blended with petrodiesel in any proportions. Biodiesel is suitable for usage at conventional diesel engines without modification. In this study, canola and safflower oil biodiesel methyl is realized by using the esterification method.. The produced biodiesels were blended in %(50) (in volume) with diesel fuel. The blends were tested in a four cycle, four cylinder Diesel engine. The effects of biodiesel addition to Diesel No. 2 on the performance and emissions of the engine were examined at full load. The resulting performance values were found to be similar to diesel fuel. In general, specific fuel consumption of biodiesel is higher than diesel at all engine loads. Significant difference between the exhaust temperature is not determined. AB50 biodiesel compared to diesel HC emissions at high loads began to decline. NOx, CO2 and O2 emissions ratio has increased at high loads for Biodiesel fuels. Experimental results showed that the produced biodiesels can be partially substituted for the diesel fuel at most operating conditions in terms of the performance parameters and emissions without any engine modification and preheating of the blends.Öğe Prediction of the thermal conductivity of lightweight building materials utilizing backpropagation neural network method(Fırat Üniversitesi, 2015) Oktay, Hasan; Polat, Süleyman; Fidan, ŞehmusThe growing concern about energy consumption of heating and cooling of buildings has led to a demand for improved thermal performances of building materials. In this study, an experimental investigation is performed to predict the thermal insulation properties of wall and roof structures of which the mechanical properties are known, by using backpropagation artificial neural network (ANNs) method. The produced samples are cement based and have relatively high insulation properties for energy efficient buildings. In this regard, 102 new samples and their compositions are produced and their mechanical and thermal properties are tested in accordance with ASTM and EN standards. Then, comparisons have been made between the determined thermal conductivity of the newly produced structures, which are obtained from experimental method and ANN method that uses mechanical properties as input parameters. From the test results, since the percentage errors in the thermal conductivity values between experimental data and neural network prediction vary from - 1.09% to 6.4%, It can be concluded that the prediction of the artificial neural network has proceed in the correct manner.Öğe Binalarda duvarlardan gelen ısı kazanımı hesaplamasında kullanılan soğutma yükü sıcaklık farkı CLTD değerlerinin hesaplanması(Türk Tesisat Mühendisleri Derneği, 2012) Oktay, Hasan; Yumrutaş, Recep; Zainal, OmarÖğe Experimental and articial neural network based studies on thermal conductivity of lightweight building materials(European Journal of Technique (EJT), 2017-04-01) Oktay, Hasan; Fidan, Şehmus; Sevim, Davut; Polat, SüleymanThe growing concern about energy consumption of heating and cooling of buildings has led to a demand for improved thermal performances of building materials. In this study, an experimental investigation is performed to predict the thermal insulation properties of wall structures of which the mechanical properties are known; by using Levenberg-Marquardt training algorithm based artificial neural network (ANNs) method for energy efficient buildings. The produced samples are cement based and have relatively high insulation properties for energy efficient buildings. In this regard, 102 new concrete samples and their compositions are produced and their mechanical and thermal properties are tested in accordance with ASTM and EN standards. Then, comparisons have been made between the experimental results and the ANN predicted results. It can be concluded that thermal performance of lightweight materials could be predicted with high accuracy using artificial neural network approach.Öğe Gerçek ve sabit termofiziksel özelliklere sahip duvarlar ve çatılar için elde edilen ısı kazancı değerlerinin karşılaştırılması(Batman Üniversitesi, 2018) Oktay, Hasan; Yumrutaş, Recep; Demir, Mehmet Emin; Işık, Mehmet Zerrakki
