Browsing by Author "Karakoyun, Y."

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Artificial Neural Network Modeling for Multi-Parameter Performance Prediction of Electronically Commutated Fan Coils Based on Experimental Data
(Springer Science and Business Media B.V., 2025) Uguz, B.; Çolak, A.B.; Karakoyun, Y.; Gemici, Z.; Dalkılıç, A.S.
The main problems with the selection and operation of fan coils in air conditioning systems impact thermal comfort and energy efficiency, and research on fan coil performance at various operating points is inadequate. No research on artificial neural networks has been undertaken about a concealed ceiling-type electronically commutated motor fan coil that has been subjected to extensive experimental assessments. Four artificial neural networks were trained using 1700 test points to predict the thermal performance and capacity as a main aim. The experiments were conducted in a test apparatus designed according to related standards and an indoor air and heat exchanger fluid regime based on international test norms. The first model estimated air flowrate using six input parameters. The second one estimated air outlet temperature and total cooling capacity using five input parameters. Then, the third one estimated heat exchanger fluid side pressure loss using five input parameters. Lastly, the fourth one estimated air outlet temperature, fan power, and total cooling capacity using eight-input parameters. The Levenberg–Marquardt training algorithm was employed in the feedforward backpropagation multilayer perceptron network model comprising 10 neurons in the hidden layer. The deviation obtained for the air flowrate was − 0.255% in the first one, while the deviations obtained for the air outlet temperature and cooling capacity were − 0.195, − 0.012%, respectively, in the second one. In the third one, the fluid pressure loss exhibited a deviation of − 0.014%. In contrast, the air outlet temperature, cooling capacity, and fan power exhibited deviations of + 0.045, − 0.014, and + 0.283%, respectively, in the fourth one. This study promotes energy-efficient industries using artificial intelligence-driven performance modeling as a collaboration sample between university and industry. © Akadémiai Kiadó Zrt 2025.
The Effect of the Important Variables for the Design Novel Milli-Channel Cooling System on the Evaporator Performance by the Taguchi Method
(Springer Science and Business Media B.V., 2025) Koca, A.; Mustafaoglu, M.; Karakoyun, Y.; Dalkilic, A.S.
Optimizing controllable parameters is crucial to milli-channel cooling system design. This study investigates the heat transfer and hydrodynamic properties of a novel annular flow boiling process of water in milli-channels with better pulsation that passes through a rectangular cross section at a constant temperature. By optimizing system operating parameters and vapor and liquid recirculation, the main novelty in this suggested approach is the achievement of continuous thin-film (micron-sized) annular flow conditions. The 3D simulation model created by a 1D simulation technique has certain boundary restrictions to guarantee the existence of a thin layer of annular flow across the boiler’s whole surface. In Taguchi analysis, the signal-to-noise ratio is determined by using the following input parameters: the Reynolds number, the heated surface temperature, and the pulsatile character of fluid flow. According to the findings, the vapor quality in pulsatile flow is estimated to be 2% to 3% greater than in continuous flow. As thin-film thickness increases, wall temperature declines toward flow. Moreover, there is an approximate 2.5% increase in the mean heat transfer coefficients for pulsatile flow cases compared to continuous flow cases. Furthermore, the average vapor velocity in pulsatile flow is lower than that in continuous flow, according to an analysis of the velocity distributions for each reference zone. The average surface temperature at specified planes in pulsatile flow scenarios is ~ 0.5 K higher than continuous flow situations. © Akadémiai Kiadó Zrt 2025.
An Experimental Performance Analysis of Canal-Mounted Photovoltaic Systems Regarding Energy Production and Water Conservation
(Elsevier Ltd, 2025) Canbaz, A.; Karakoyun, Y.; Uzmus, H.
Traditional ground-mounted photovoltaic (PV) systems encounter considerable obstacles, including land scarcity and performance decline at elevated operating temperatures. Canal-mounted photovoltaic (CM-PV) systems have significant benefits by leveraging existing canal infrastructure, improving thermal efficiency, and mitigating water evaporation—an increasingly pressing concern in dry and water-scarce areas. Nonetheless, empirical investigations on CM-PV systems are limited in the literature, especially regarding practical application and operational constraints. This research seeks to assess the energy efficiency and water conservation capabilities of CM-PV systems in comparison to conventional ground-mounted PV panels under actual working settings inside a hot and arid area. Experiments were performed to assess panel surface temperatures, energy efficiency, and water evaporation at various tilt angles (8°, 23°, and 38°). CM-PV panels demonstrated surface temperatures that were up to 6.33 °C lower and, on average, 4.2 °C lower than ground-mounted panels, leading to enhanced energy efficiency. Shaded canals equipped with photovoltaic panels shown reduced evaporation rates relative to open canals; specifically, at an 8° tilt, water evaporation decreased from 10 to 6 L. Reduced tilt angles increased closeness to the water surface, hence enhancing cooling and performance. Although data illustrate the benefits of CM-PV systems in energy and water management, obstacles persist, such as long-term durability, integration into diverse canal geometries, and cost-effectiveness. This study offers substantial empirical data to address these deficiencies and supports the potential of CM-PV systems as a dual-benefit approach for sustainable energy and water conservation. © 2025 International Solar Energy Society
A New Hybrid Cfd Approach To Study the Impact of Forced Convection on Radiant Cooled Wall With Baseboard Diffuser Including Various Vane Angles
(Elsevier Masson s.r.l., 2025) Caliskan Temiz, M.; Bacak, A.; Camci, M.; Karakoyun, Y.; Acikgoz, O.; Dalkilic, A.S.
The current work examines the effect of forced convection on thermal comfort in a space, including radiant wall cooling and an innovative floor-level diffuser system. It examines the impact of various vane angles on thermal comfort in room air conditioning at 15°, 30°, 45°, 60°, and 75°, and employs experimental data to confirm a hybrid 3D computational fluid dynamics (CFD) model. A new floor-level diffuser system delivers air at temperatures between 18 °C and 22 °C, with supply air velocities of 5 m/s and 10 m/s measured at the exit side of diffuser while the supply water temperature is kept constant at 14 °C. In the hybrid 3D solution, experimentally derived convective heat transfer coefficients (CHTCs) for forced airflow are utilized. This is accomplished by merging a k-ω model with a hydronic radiant panel system that incorporates forced convection. The analysis examines temperature and velocity distributions, CHTCs on the radiant-cooled wall, and the PMV-PPD components. Results indicate that at a supply air velocity of 5 m/s, thermal comfort parameters do not satisfy PMV and PPD indices, except in proximity to the diffuser. Nevertheless, elevating the supply air velocity to 10 m/s ensures thermal comfort across the space, with the exception of regions next to the cooled wall surfaces. The examination of several vane angles indicated that a 45° angle yields the most advantageous thermal comfort conditions, irrespective of air velocity. The CHTC adjacent to the radiant wall is roughly 6 W/m2K at a velocity of 5 m/s and rises to 8 W/m2K at 10 m/s. The temperature disparity between the head and ankle regions at 5 m/s adheres to the 3 °C tolerance established by international standards. The study determines that a 45° vane angle ensures best thermal comfort, and the devised numerical method yields significant insights for the construction of analogous indoor settings. © 2025 Elsevier Masson SAS