Yazar "Eskin, Nurdil" seçeneğine göre listele

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    Air-Water Two-Phase Flow Dynamics Analysis in Complex U-Bend Systems through Numerical Modeling
    (Mdpi, 2024) Kukrer, Ergin; Eskin, Nurdil
    This study aims to provide insights into the intricate interactions between gas and liquid phases within flow components, which are pivotal in various industrial sectors such as nuclear reactors, oil and gas pipelines, and thermal management systems. Employing the Eulerian-Eulerian approach, our computational model incorporates interphase relations, including drag and non-drag forces, to analyze phase distribution and velocities within a complex U-bend system. Comprising two horizontal-to-vertical bends and one vertical 180-degree elbow, the U-bend system's behavior concerning bend geometry and airflow rates is scrutinized, highlighting their significant impact on multiphase flow dynamics. The study not only presents a detailed exposition of the numerical modeling techniques tailored for this complex geometry but also discusses the results obtained. Detailed analyses of local void fraction and phase velocities for each phase are provided. Furthermore, experimental validation enhances the reliability of our computational findings, with close agreement observed between computational and experimental results. Overall, the study underscores the efficacy of the Eulerian approach with interphase relations in capturing the complex behavior of the multiphase flow in U-bend systems, offering valuable insights for hydraulic system design and optimization in industrial applications.
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    Data-driven building energy benchmark modeling for bank branches under different climate conditions
    (Elsevier, 2023) Kukrer, Ergin; Aker, Tugce; Eskin, Nurdil
    Energy benchmarking in buildings is a significant analytical method to determine and classify the energy performance of buildings. The objective of the present paper is to establish a compre-hensive data-driven energy benchmark model for banking buildings. In this context, 587 bank branches are selected to cover every climatic region in Turkey, with more than 210,000 data obtained from the installed energy analyzers and building energy audits. A mathematical model is developed and verified to define the EUI of the existing bank branches. Calculated energy scores and benchmark study implied an energy efficiency potential across the sector. Investigating the results of underperforming buildings, the building shell and construction date are found to be significant. As results indicated an efficiency potential, a scenario-based energy benchmark model is proposed based on the new insulation regulations in Turkey to see the possible energy con-sumption and carbon gas emission reductions. The developed model is adapted to the scenario -based model by revising U-values concerning the regulation and climate zones. The scenario -based strategy has led to a 2136.7 MWh/year reduction in energy consumption. The total EUI was found to decrease from 159.44 to 124.35 kWh/m2year, also resulting in a 20.5% improve-ment equal to 2057.3 equivalent tons of CO2/year in annual GHG emissions with the application of new regulations.
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    Experimental assessment of local void fraction and flow development in a U-bend piping system for air-water two-phase flow
    (Pergamon-Elsevier Science Ltd, 2023) Kukrer, Ergin; Eskin, Nurdil
    This paper presents an experimental investigation of air-water flow in a complete piping system, covering the two-phase flow development in injector, upstream, U-bend and downstream sections separately. Local void fractions and bubble numbers were measured with a dual optical probe. Two-phase flow conditions were established through a 40 mm diameter pipe with 180 l/min water and 30, 35 and 40 l/min air flow rates by the designed circular injector. In the horizontal upstream section, where a transition from bubbly to plug flow with elongated Taylor bubbles was observed, the fully-developed flow is reached at 37.5D. The average void fraction in the upstream region was acquired as 9.2%, 11.5% and 13.4%. The effect of two vertical 90-degree and one vertical 180-degree elbows is assessed in the U-bend section. While bubble break-up and locally annular flow were observed in the vertical upward section; bubble coalescence and accumulation resulting in higher average void fractions (30.8%, 33.8%, and 35.6%) were present in the downward section due to body forces and interphase interactions. After the bend section, disturbances were detected in the gas phase due to the increased water velocity and centripetal forces. Accordingly, a local transition to temporary churn flow is observed in the earlier downstream sections. The experimental assessment in our study shows that the system should be considered and analyzed as a whole to determine local transitions and differences in the flow regimes due to singularities in geometry.