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Öğe An exergy analysis of a concentric tube heat exchanger using hBN-water nanofluids(Inder Science Publishers, 2021) Budak Ziyadanoğulları, Neşe; Perçin, SüleymanThis study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 8,700) for parallel flow operation at 170 W. The exergy loss of water at the highest Reynolds number (Re = 8,700) for parallel flow operation increased by 15.7%, 24.8% and 49.8% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. Exergy loss of water at the highest Reynold number (Re = 8,700) for counter flow operation increased by 11.3%, 17.3% and 29.2% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).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 The efficiency of Al2O3 water nanofluid on a flat plate solar collector(SETCOR publications, 2015) Budak Ziyadanoğulları, Neşe; Yıldız, Cengiz; Argunhan, Zeki; Tekalp, Selen; Yücel, Halit LutfiSolar collectors are particular kind of heat exchangers that transform solar radiation energy into internal energy of the transport medium. One of the most effective methods is replacing the working fluid (water, ethylene glycol, engine oil…) by developing a new class of fluids with a higher thermal conductivity for thermal systems. In the present work the effect of Al2O3-water, as working fluid, on the efficiency of a flat plate solar collector is investigated experimentally. The mass flow rate of nanofluid is 150 Lit/h. The volume fraction of the nanoparticles is 0.2 %, 0.4 % and 0.8 % respectively. The results reveal the impact and importance of each of these parameters. Experimental results reveal that utilizing the nanofluid increases the collector efficiency in comparison to water as an absorbing mediumÖğe An investigation of the influence of thermophysical properties of multilayer walls and roofs on the dynamic thermal characteristics(Mugla Sitki Kocman University, 2016-06-09) Oktay, Hasan; Argunhan, Zeki; Yumrutaş, Recep; Işık, Mehmet Zerrakki; Budak Ziyadanoğulları, NeşeThe growing concern about energy consumption of heating and cooling of buildings has led to a demand for improved thermal performances of building materials. To achieve this goal, in this study, an investigation is performed to analyze the influence of thermophysical properties and thickness of various multilayer building walls or roofs in a building on the dynamic thermal characteristics, such as the decrement factor (DF), time lag (TL) and heat gain. In order to find the thermal performance characteristics of building structures, such as briquette, brick, blockbims and autoclaved aerated concrete (AAC), which are commonly used in Turkey, an analytical solution method was developed in a computer program in MATLAB and results are compared to determine suitable wall or roof material. Calculation method for the heat flow is based on solution of transient heat transfer problem for the multilayer structures. The program is executed to calculate hourly heat gain values for these samples over a period of 24 h during design day for Gaziantep, Turkey. It was found that thermophysical properties of roofs or walls have a very profound effect on the time lag (TL), decrement factor (DF) and also heat gain.Öğe The experimental study of nanofluids on a flat-plate solar collector(Fırat Üniversitesi, 2017) Budak Ziyadanoğulları, Neşe; Yücel, Halit Lutfi; Yıldız, Cengiz; Işık, Mehmet KemalSolar collectors are particular kind of heat exchangers that transform solar radiation energy into internal energy of the transport medium. One of the most effective methods is replacing the working fluid (water, ethylene glycol, engine oil…) by developing a new class of fluids with a higher thermal conductivity for thermal systems. In the present work the effect of Al2O3 -water, as working fluid, on the efficiency of a flat plate solar collector is investigated experimentally. The mass flow rate of nanofluid is 250 l/h. The volume fraction of the nanoparticles is 0.2 %, 0.4 % and 0.8 % respectively. The results reveal the impact and importance of each of these parameters. Experimental results reveal that utilizing the nanofluid increases the collector efficiency in comparison to water as an absorbing medium.Öğe Doğalgazın araçlarda motor yakıtı olarak kullanımının değerlendirilmesi(Dicle Üniversitesi, 2013) Budak Ziyadanoğulları, Neşe; Bayındır, Hasan; Yücel, Halit LutfiClean and cheap alternative energy sources begun to be explored because of increase in air pollution due to exhaust waste of vehicles, global warming and parallel rise in fossil oil prices. Nowadays, natural gas, which widely used especially in houses for heating, has been considered as enviromentally and important alternative engine fuel owing to high combustion efficiency; own reserves more than fossil oil in the world and more cheaper than fossil oil. In this study, natural gas reserves, storage and usage methods in vehicles, applications in different engine technologies have been investigated. In addition, negative and positive aspects have been evaluated resulting from the use of natural gas in internal combustion engines.Öğe Farklı kurutma yöntemlerinin incelenmesi ve kurutma parametrelerinin ürünler üzerindeki etkisinin karşılaştırılması(ISPEC Publishing, 2019) Budak Ziyadanoğulları, Neşe; Baskın, Zozan; Dongaz, NecipÖğe Thermal performance enhancement of flat-plate solar collectors by means of three different nanofluids(Elsevier, 2018-12) Budak Ziyadanoğulları, Neşe; Yıldız, Cengiz; Yücel, Halit LutfiSolar energy, which comes first among renewable energy sources, enables efficient use of energy with many applications due to its low operating cost and environmental friendliness. In this study, we experimentally investigated the effects on thermal efficiency of nanofluid and water as working fluids in flat-plate solar collector hot water solar energy systems. Nanofluids were prepared by adding Al2O3, CuO, and TiO2 nanoparticles at 0.2, 0.4, and 0.8 vol% into distilled water, and then the thermophysical properties (thermal conductivity, viscosity) of the prepared nanofluids were determined. Flow rate was adjusted to 250 l/h at given concentrations for each nanofluid in the experimental setups and data such as collector inlet and outlet temperatures, ambient and tap water temperatures; radiation, humidity, and wind speed were measured and recorded. The obtained data were used to calculate efficiencies according to ASHRAE 93-2003 standards. When compared with water, the results indicated that the use of nanofluid increased collector efficiency.Öğe Konsantrik tip bir ısı değiştiricisinde türbülatörlerin ısı transferine etkisinin deneysel incelenmesi(Dicle Üniversitesi, 2013) Budak Ziyadanoğulları, Neşe; Argunhan, Zeki; Yücel, Halit LutfiIn this study, the effect of four different types of turbulators placed inside the pipe entrance in a concentric (nested) heat exchanger on heat transfer and pressure drop has been investigated experimentally. For this purpose, an experimental system of heat exchanger was established in which air passed through the inner tube as hot fluid whereas water passed through the outer pipe as cold fluid. Experiments have been conducted under the same and opposite directional parallel flow conditions in order to investigate the effect of turbulators that are produced as unperforated and perforated in different positions on heat transfer and pressure drop. When the research data was analysed, it became clear that maximum heat transfer happens in the inner, outer wing and body perforated turbulators.
