Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 1Euler–Euler Numerical Model for Transport Phenomena Modeling in a Natural Circulation Loop Operated by Nanofluids(Springer, 2025) Kamenik, B.; Vovk, N.; Elcioglu, E.B.; Sezgin, F.; Ozyurt, E.; Karadeniz, Z.H.; Ravnik, J.This paper explores a computational approach to model multiphase heat transfer and fluid flow in a natural circulation loop utilizing nanofluids. We propose and implement an Euler–Euler framework in a CFD environment, incorporating an innovative boundary condition to preserve mass conservation during thermophoretic particle flux. The model’s accuracy is verified through a one-dimensional example, by comparing results against both an Euler–Lagrange model and an in-house finite volume solution. Experimental validation is conducted with aluminum oxide nanofluids at varying nanoparticle concentrations. We prepared the nanofluids and measured their thermophysical properties up to 60∘C. We assess the thermal performance of the nanofluid in natural circulation loop at different heating powers via experiment and numerical simulations. The findings reveal that the heat transfer enhancement offered by the nanofluid is modest, with minimal differences observed between the proposed Euler–Euler approach and a simpler single-phase model. The results underscore that while the Euler–Euler model offers detailed particle–fluid interactions, its practical thermal advantage is limited in this context. © The Author(s) 2025.Article Citation - WoS: 20Citation - Scopus: 17Optimizing Thermal Comfort in Physical Exercise Spaces: A Study of Spatial and Thermal Factors(Elsevier, 2024) Avcı, A.B.; Balci, G.A.; Başaran, T.Fitness centers have become famous for maintaining a healthy lifestyle. They require different thermal comfort conditions and higher fresh air supply rates than other indoor spaces. However, even well-designed centers may cause discomfort due to factors such as design decisions, ventilation, overheating, and overcrowding. The standards for fitness centers do not consider these specific requirements sufficiently, so this study focuses on understanding the thermal comfort requirements during physical exercise and evaluating spatial and thermal factors affecting the thermal environment around the body. The study investigated the ceiling height, lateral and frontal distances between machines, and vent locations as spatial factors and inlet temperature and air velocity as thermal factors. A thirty-minute moderate-intensity constant work rate exercise test was conducted in a controlled climatic chamber using a cycle ergometer with six healthy male participants. The experiment conditions were simulated in CFD software using the collected data. Once a validated simulation model was provided, computational models for different environmental and spatial scenarios for the five-person cycling class were generated. Using Taguchi L9 (34) orthogonal arrays method, nine spatial scenarios were simulated with three different thermal operations each. Optimal factor levels were determined by using thermal comfort conditions (based on predicted mean vote) around the body's thermal plume. The results showed that a ceiling height of 5 m, lateral and frontal distances of 1 m and 0.5 m between machines, and Type 2 (two inlets mounted on the ceiling) ventilation strategy were optimal for achieving better thermal comfort values in a thermal condition of 18 °C and 0.2 m·s−1. The study found that increasing the ceiling height and using cross-positioned vents that project air vertically from the ceiling improved the comfort conditions significantly. It is expected that these criteria, which were determined, compared with the standards and detailed, will contribute to the production processes of comfortable exercise spaces. © 2023 Elsevier B.V.