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    Laminar Forced Convection and Entropy Generation of ZnO-Ethylene Glycol Nanofluid Flow through Square Microchannel with using Two-Phase Eulerian-Eulerian Model
    (Isfahan Univ Technology, 2019) Uysal, C.; Arslan, K.; Kurt, H.
    In this paper, convective heat transfer and entropy generation of ZnO-EG nanofluid flow through a square microchannel are numerically investigated. Flow is modelled by using Eulerian-Eulerian two phase flow model. Nanoparticle volume fraction of ZnO-EG nanofluid ranged between %1.0 and %4.0. As a result, it is found that the convective heat transfer coefficient of flow increased from 9718.15 W/m(2) K to 23010.79 W/m(2) K when 4.0% ZnO nanoparticle addition to pure EG at Re=100. Total entropy generation of ZnO-EG nanofluid decreases with increase in nanoparticle volume fraction of ZnO-EG nanofluid. It is also observed that the Bejan number decreases with increase in nanoparticle volume fraction of ZnO-EG nanofluid.
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    Laminar forced convection and entropy generation of ZnO-ethylene glycol nanofluid flow through square microchannel with using two-phase Eulerian-Eulerian model
    (Isfahan University of Technology, 2019) Uysal, C.; Arslan, K.; Kurt, H.
    In this paper, convective heat transfer and entropy generation of ZnO-EG nanofluid flow through a square microchannel are numerically investigated. Flow is modelled by using Eulerian-Eulerian two phase flow model. Nanoparticle volume fraction of ZnO-EG nanofluid ranged between %1.0 and %4.0. As a result, it is found that the convective heat transfer coefficient of flow increased from 9718.15 W/m2K to 23010.79 W/m2K when 4.0% ZnO nanoparticle addition to pure EG at Re = 100. Total entropy generation of ZnO-EG nanofluid decreases with increase in nanoparticle volume fraction of ZnO-EG nanofluid. It is also observed that the Bejan number decreases with increase in nanoparticle volume fraction of ZnO-EG nanofluid. © 2019 Isfahan University of Technology.
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    A Numerical Analysis of Laminar Forced Convection and Entropy Generation of a Diamond-Fe3O4/Water Hybrid Nanofluid in a Rectangular Minichannel
    (Isfahan Univ Technology, 2019) Uysal, C.; Gedik, E.; Chamkha, A. J.
    The convective heat transfer and entropy generation of diamond-Fe3O4/water hybrid nanofluid through a rectangular minichannel is numerically investigated under laminar flow conditions. Nanoparticle volume fractions for diamond-Fe3O4/water hybrid nanofluid are in the range 0.05-0.20% and Reynolds number varies from 100 to 1000. The finite volume method is used in the numerical computation. The results obtained for diamond-Fe3O4/water hybrid nanofluid are compared with those of diamond/water and Fe3O4/water conventional nanofluids. It is found that 0.2% diamond-Fe3O4 hybrid nanoparticle addition to pure water provides convective heat transfer coefficient enhancement of 29.96%, at Re=1000. The results show that diamond-Fe3O4/water hybrid nanofluid has higher convective heat transfer coefficient and Nusselt number when compared with diamond/water and Fe3O4/water conventional nanofluids. For diamond-Fe3O4/water hybrid nanofluid, until Re=600, the lowest total entropy generation rate values are obtained for 0.20% nanoparticle volume fraction. However, after Re=800, diamond-Fe3O4/water hybrid nanofluid with 0.20% nanoparticle volume fraction has the highest total entropy generation rate compared to other nanoparticle volume fractions. A similar pattern emerges from the comparison with diamond/water and Fe3O4/water conventional nanofluids. For 0.2% nanoparticle volume fraction, diamond-Fe3O4/water hybrid nanofluid and diamond/water nanofluid have their minimum entropy generation rate at Re=500 and at Re=900, respectively. Moreover, this minimum entropy generation rate point changes with nanoparticle volume fraction values of nanofluids.
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    Present status of energy use in Karabuk industry (Turkey) and energy conversion potential in its steel production sector
    (2011) Polat, R.; Özcan, H.; Uysal, C.
    In this paper, economic and industrial parameters of Karabuk city have been assessed, a detailed comparison of production sectors has been done and several designations have been made on energy waste in the energy-intensive steel industry. 22% of total industrial facilities in Karabuk produce steel and its derivatives, but 90% of the total energy is used by steel production industry. Steel production needs high energy consumption. At the production process of steel, high efficient electrical energy converts into low efficient thermal energy. This transformation brings a high rate of energy loss. By increasing energy need in the world, those who are concerned maintain energy saving attempts and designate energy loss ratios of energy systems. In this study, specifications of energy wastes of energetic systems have been estimated and energy efficiency potential of various energetic systems has been evaluated. Assessments have indicated that 20 to 45%, 25 to 35%, 20 to 45%, 20 to 40%, 15 to 30%, 15 to 45%, 10 to 30% of average current energy in steel, textile, food, chemical process, mining, casting and cement and other sectors can be conserved, respectively. © 2011 Academic Journals.
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    THERMOECONOMIC ANALYSIS OF A WATER TO WATER HEAT PUMP UNDER DIFFERENT CONDENSER AND EVAPORATOR CONDITIONS
    (Yildiz Technical Univ, 2019) Aksu, B.; Uysal, C.; Kurt, H.
    A thermoeconomic analysis of a water to water heat pump are performed under different condenser and evaporator conditions. Experiments are realized for different volumetric inlet temperatures of 14.4, 17 and 19 degrees C and different volumetric flow rates of 50, 100, 150 lt/h for condenser cooling water. Same inlet temperatures with condenser cooling water are used for evaporator water inlet, while constant volumetric flow rate of 100 lt/h is used for each case. Modified Productive Structure Analysis (MOPSA) is used for thermoeconomic analysis. It is found that increases in inlet temperature and in volumetric flow rate cause to decrease in both the unit cost of heat delivered (C-H) and the unit cost of entropy generation (C-S). As a result, in the case of T-in =14.4 degrees C and (for all) over dot = 50 lt/h, C-H and C-S values are obtained to be 0.0489 $/kWh and 0.0221 $/kWh, respectively, while C-H and C-S values are obtained to be 0.0385 $/kWh and 0.0175 $/kWh for T-in =19 degrees C and (for all) over dot = 150 lt/h, respectively.
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    Thermoeconomic diagnosis of an air-cooled air conditioning system
    (Inderscience Publishers, 2018) Yoo, Y.; Oh, H.-S.; Uysal, C.; Kwak, H.-Y.
    Diagnosis of a 120-kW air-cooled air conditioning system under faulty conditions was performed using modified productive structure analysis. Unit cost of cooling capacity for the system and lost cost flow rate for components were calculated based on data obtained by using a simulator for the cases of pre-fixed faulty and normal operating conditions. The relative malfunction (RMF) and the relative difference in the lost cost flow rate between real and normal operations (RDLC) were found to be effective indicators to identify the malfunction components. Results revealed that malfunction due to fouling at the condenser and evaporator, compressor valve leakage, the superheating in the suction line and refrigerant undercharge, whose fault levels by the percent degradation induced in the cooling capacity are 3.4%, 10.5%, 15.1%, 3.5% and 4.1%, respectively, can be identified. Unit cost of the cooling capacity of the system increases when malfunction occurs at any component in the air conditioning system. Copyright © 2018 Inderscience Enterprises Ltd.