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    Exergy analysis of Eregli sugar factory
    (EMERALD GROUP PUBLISHING LTD, 2015) Sahin, Necmettin; Kaplan, Erkan; Bayrak, Mustafa; Yaka, I. Faruk; Gungor, Afsin
    Progressive decline in world energy resources, rising costs, on behalf of the various studies has led businesses to use energy resources efficiently. This work is at the top of the exergy analysis. In this study, using data from Eregli Sugar Factory 2010-2011 campaign year for sugar production processes, the first law of thermodynamics (energy analysis) and analysis of these condlaw (exergy analysis) were conducted. Depending on there sults of this analysis of the sugar production process yields the first and these cond law is calculated. Obtained in the light of the secalculation stoin crease theen ergy efficiency of the plant, was tetoprovide energy to gainth embackand give direction to the development of new technologies Eregli Sugar Factory recommendations were made.
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    Increased fuel burn up in a CANDU thorium reactor using weapon grade plutonium
    (ELSEVIER SCIENCE SA, 2006) Sahin, Somer; Yildiz, Kadir; Sahin, Haci Mehmet; Sahin, Necmettin; Acir, Adem
    Weapon grade plutonium is used as a booster fissile fuel material in the form of mixed ThO2/PuO2 fuel in a Canada Deuterium Uranium (CANDU) fuel bundle in order to assure the initial criticality at startup. Two different fuel compositions have been used: (1) 97% thoria (ThO2) + 3PuO(2) and (2) 92% ThO2 + 5% UO2 + 3% PuO2. The latter is used to denaturize the new U-233 fuel with U-238. The temporal variation of the criticality k(infinity) and the burn-up values of the reactor have been calculated by full power operation for a period of 20 years. The criticality starts by k infinity = similar to 1.48 for both fuel compositions. A sharp decrease of the criticality has been observed in the first year as a consequence of rapid plutonium burnout. The criticality becomes quasi constant after the second year and remains above k infinity > 1.06 for similar to 20 years. After the second year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn up could be achieved with the same fuel material (up to 500,000 (MWD)-D-./T), provided that the fuel rod claddings would be replaced periodically (after every 50,000 or 100,000 MW.D/T). The reactor criticality will be sufficient until a great fraction of the thorium fuel is burnt up. This would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically. (c) 2006 Elsevier B.V. All rights reserved.
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    Neutronic performance of CANDU reactor fuelling with ThC2/(UC2)-U-233
    (WILEY-BLACKWELL, 2011) Yildiz, Kadir; Sahin, Necmettin; Alkan, Mahmut
    U-233 isotope is used as a booster fissile fuel material in the form of mixed ThC2/(UC2)-U-233 fuel in a Canada Deuterium Uranium (CANDU) fuel bundle in order to assure the initial criticality at startup. Three different fuel compositions have been used: (1) 97% ThC2+3% (UC2)-U-233, (2) 98% ThC2+2% (UC2)-U-233 and (3) 99% ThC2+1% (UC2)-U-233. The temporal variation of the criticality k(infinity) and the burn-up values of the reactor have been calculated by full-power operation for a period of 20 years. The criticality starts by k(infinity) = 1.541, 1.355 and 0.995 for modes of (1), (2) and (3) fuel compositions, respectively. A sharp decrease in the criticality has been observed in the first 2 years as a consequence of rapid U-233 burnout fuelling with (1) and (2) modes. The criticality becomes quasi-constant after the second year and remains above k(infinity) similar to 1.06 for 20 years. After the second year, the CANDU reactor begins to operate practically as a thorium burner. Very high burnup could be achieved with the same fuel materials (up to 500 000 MW day t (1)), provided that the fuel rod claddings would be replaced periodically (after every 500 00 or 100 000 MW day t(-1)). The reactor criticality will be sufficient for fuelling with (1) and (2) modes until a great fraction of the thorium fuel is burnt up. This would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically. Copyright (C) 2010 John Wiley & Sons, Ltd.
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    The Effects of the Different Tritium Breeding Materials to Fusil and Fisil Fuel Breeding in a ThSi2 Fuelled- Flibe Moderated Fusion-Fission Hybrid Reactor
    (Gazi Univ, 2007) Acir, Adem; Yildiz, Kadir; Alkan, Mahmut; Sahin, Necmettin
    In this work, in a ThSi2 fuelled-flibe moderated fusion-fission reactor in the tritium breeding zones of the reactor are used four different Li compound, respectively, Li2TiO3, Li2ZrO3, Li4SiO4 and Li2O. D-T fusion reactions are used as a fusion neutron source which produces 14.1 MeV neutrons with averaged energy. Fusil and fissile fuel breeding rates, fission energy breeding rates and fission power production are investigated for Delta t=10 days during a reactor operation period in four years. In tritium breeding zones used Li2O of the reactor provided highest fusil breeding rate whereas, highest value of fissile breeding and production of the fission energy are reached with using of Li2TiO3 and Li2ZrO3 in tritium breeding zones of the blanket.
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    Thermal Analysis of Chip on Board Packaging of High Power Led's with Heat Pipe Using Cfd for Street Lights
    (Gazi Univ, 2018) Cicek, Burcu; Sahin, Necmettin; Alkan, Mahmut
    In this study, in order to provide heat dissipation of the high power LEDs to be used for street illumination, U-shaped cylindrical copper heat pipes are used. Thermal analysis of this system was carried out numerically in the ANSYS Fluent software. Firstly, thermal analysis was performed for different numbers, diameters and lengths of heat pipes and optimum values were obtained. Afterwards, the optimum materials to be used as components of LED packages were determined. In addition, the effect of the power applied to the LED chip and of ambient temperature on the temperature distribution of the whole system was examined.
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    Thermal analysis of chip on board packaging of high power led’s with heat pipe using Cfd for street lights
    (Gazi Universitesi, 2018) Cicek, Burcu; Sahin, Necmettin; Alkan, Mahmut
    In this study, in order to provide heat dissipation of the high power LEDs to be used for street illumination, U-shaped cylindrical copper heat pipes are used. Thermal analysis of this system was carried out numerically in the ANSYS Fluent software. Firstly, thermal analysis was performed for different numbers, diameters and lengths of heat pipes and optimum values were obtained. Afterwards, the optimum materials to be used as components of LED packages were determined. In addition, the effect of the power applied to the LED chip and of ambient temperature on the temperature distribution of the whole system was examined. © 2018, Gazi University Eti Mahallesi. All rights reserved.