Yazar "Oztop, Hakan F." seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • [ X ]
    Öğe
    Analyzing of thermal mixing phenomena in a rectangular channel with twin jets by using artificial neural network
    (Elsevier Science Sa, 2013) Kok, Besir; Uyar, Murat; Varol, Yasin; Koca, Ahmet; Oztop, Hakan F.
    In this study, an experimental investigation was carried out to analyze the thermal mixing phenomena in a rectangular cross-section narrow channel. The channel has two circular water jet inlets, in different temperatures and a circular exit hole to supply continuity of mass. Several parameters were used in the experiments to control thermal mixing efficiency such as inclination angle of the channel, ratio of flow rate of inlet fluid, temperature difference between hot and cold jets and jet inlets diameters. Thermal mixing index was calculated from the measured temperatures. In order to reduce experimental time, an artificial neural network (ANN) model was built with limited number of measurements for a forward model. The obtained results indicated that estimation data of ANN shows that the ANN model can predict the output parameters without carry out any experiment. (C) 2013 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Effects of different fin parameters on temperature and efficiency for cooling of photovoltaic panels under natural convection
    (Pergamon-Elsevier Science Ltd, 2019) Bayrak, Fatih; Oztop, Hakan F.; Selimefendigil, Fatih
    The photovoltaic panels are one of the most efficient energy systems that generate electricity by absorbing the solar radiation. Nevertheless, when the sun's rays are converted to electricity, a high amount of waste heat is generated. Therefore, the efficiency of photovoltaic (PV) panels needs to be studied to minimize the amount of waste heat. There is a non-linear relationship between the temperature, the current and the voltage values produced by the PV panels. In the present study, the performance of 75 W PV panels with polycrystalline cell structure under Elazig, Turkey climatic conditions were experimentally investigated. The system performances such as temperature, power and efficiencies were analyzed by applying different fin parameters (length, sequences) to PV panels. The aluminum fins were applied with 10 different configurations as given by A1-A10. The cell temperatures, output powers, power loss ratios and energy-exergy efficiencies were calculated based on measurements of the experimental study. It was observed that the temperature did not distributed homogeneously on the PV panel. In terms of the efficiency, the fins are designed as staggered array and the 7 cm x 20 cm dimensions showed the best results. The highest energy and exergy efficiencies values of the finned panels (A5) were calculated as 11.55%, and 10.91%, respectively.
  • [ X ]
    Öğe
    Effects of static and dynamic shading on thermodynamic and electrical performance for photovoltaic panels
    (Pergamon-Elsevier Science Ltd, 2020) Bayrak, Fatih; Oztop, Hakan F.
    An experimental examination has been performed on the performance assessment of different shading shapes on photovoltaic panels by using energy-exergy analysis methods in this study. The problem is important due to decreasing of performance of PV panel with shading effect. A non-transparent material and powder were used for static shading while the time-varying shading effect of a chimney for dynamic shading was applied on to the system. Novelty of the work is to use diagonal shading on energy and exergy efficiency. Moreover, thermal camera technique was used to observe the effects of temperature distribution as a novel technique for PV panels. The photovoltaic panel was kept outside for one month in terms of dusty shading. For other static shading, artificial shadows of three different triangular shapes (40 * 40 cm for Case I, 36 * 60 cm for Case II and 60 * 36 cm for Case III) were created. The energy and exergy efficiencies of all systems under the same solar radiation were compared. The Case I-III under the same solar radiation was imaged by using a thermal camera and the effect of shading on photovoltaic panels and hot spot formation were examined. The results showed that the highest energy efficiency value was found to be 10.54% for the reference panel, 9.70% for the dusty panel, 4.16% for Case I, 4.27% for Case II and approximately zero for Case III. In the panel of dynamic shading, the lowest and the highest efficiency values were found as 0.86% and 10.27%, respectively.
  • [ X ]
    Öğe
    Experimental analysis and dynamic modeling of a photovoltaic module with porous fins
    (Pergamon-Elsevier Science Ltd, 2018) Selimefendigil, Fatih; Bayrak, Fatih; Oztop, Hakan F.
    In this study, experimental analysis and performance predictions of solar photovoltaic (PV) module equipped with porous fins were performed. The experimental setup was tested in Technology Faculty of Firat University, Elazig of Turkey which is located at 36 and 42 North latitudes. The PV module was oriented facing south and tilted to an angle of 36 with respect to the horizontal in order to maximize the solar radiation incident on the glass cover. Experimental analysis was conducted for configurations where PV module is equipped with porous metal foams. A multi-input multi-output dynamic system based on artificial neural networks was obtained for the PV configuration with and without fin by using the measured data (ambient temperature, PV panels back surface temperatures, current, voltage, radiation and wind velocity) from the experimental test rig. It was observed that adding porous fins to the PV module results in performance enhancements. The developed mathematical model based on dynamic neural networks can be used for further development and performance predictions of these systems. (C) 2018 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Experimental study for the application of different cooling techniques in photovoltaic (PV) panels
    (Pergamon-Elsevier Science Ltd, 2020) Bayrak, Fatih; Oztop, Hakan F.; Selimefendigil, Fatih
    This article contains the experimental investigations of different cooling methods used for photovoltaic (PV) panels. Phase change material (PCM), thermoelectric (FE) and aluminum fins were chosen as the cooling methods. The CaCl2 center dot 6H(2)O is chosen as one of the PCM which is widely used in the cooling of PVs and the other is the PCM with melting temperature above the surface temperature of the PV panel. By using TE material in different numbers (6, 8 and 12) and aluminum fins in different layouts, surface temperatures and output powers of PV panels were compared. It is observed that the PCM which is not chosen appropriately has insulation feature in the PV panel and enhances the temperature of the panel and decreases the output power. When the most successful cooling methods were tested under the same environmental conditions, PV with fin system produced the highest power generation of 47.88 W while PV with PCM and TEM produced the lowest power generation of 44.26 W.