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    A comparative thermodynamic analysis on different exergetic efficiency methods for a solar photovoltaic module
    (Inderscience Publishers, 2017) Özalp, M.; Bayat, M.
    In this paper, a comparative study on the different exergetic performance of a solar photovoltaic (PV) module is presented. The exergetic efficiency of the PV module was obtained as functions of environmental, operational and design parameters, and calculated in four cases. In Case I, electrical exergy, thermal exergy and exergy destructions were considered. In Case II, a novel expression on the calculation of solar exergy was proposed. In Case III, chemical and physical exergy components including enthalpy and entropy concepts were discussed. In Case IV, an empirical expression depending on the power conversion efficiency of the system was used. As a result, the exergy efficiency varied in the range 9.25% to 18.32% in Case I, whereas it varied between 9.41% and 18.34% in Case II. In addition, the exergy efficiency varied from 6.58% to 19.99% in Case III, whereas it varied in the range of 9.30% to 18.89% in Case IV during November 2015. Copyright © 2017 Inderscience Enterprises Ltd.
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    Energy, Exergy and Exergoeconomic Analysis of a Solar Photovoltaic Module
    (Elsevier Inc., 2018) Bayat, M.; Ozalp, M.
    This chapter describes an experimental study performed on a polycrystalline solar photovoltaic (PV) module to determine its performance characteristics through energy, exergy, and exergoeconomic analyses. Energy and exergy analyses were performed according to the first and the second laws of thermodynamics. Thus, energy and maximum electrical, power conversion, and exergy efficiencies were obtained as functions of environmental, operational, and design parameters. The exergoeconomic analysis was performed by applying the exergy destruction and energy loss rate of the PV, with an aim of determining the actual product cost of the system. According to the analyses conducted in this study, the power conversion efficiency varied in the range 9.6% to 18.3%, whereas the maximum electrical efficiency varied between 12.6% and 23.12%. In addition, with a gradual increase, the energy efficiency varied from 24% to 68.4%, whereas the corresponding exergy efficiency varied in the range of 9.3% and 18.1% throughout the month. © 2018 Elsevier Inc. All rights reserved.
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    Fuel cells basics and types
    (Elsevier, 2023) Bayat, M.; Kaskun, Ergani, S.; Dasdemirli, Y.; Kayfeci, M.
    Fuel cells are clean energy-converting devices that directly convert the chemical energy of the fuel into electrical energy accompanied by an oxidant. Thanks to their prominent features, including their quiet operation, modularity, and high energy efficiency, they have a broad range of use. As fuel cells generate energy through electrochemical processes, their operating conditions may be similar to those of conventional batteries. However, the characteristic that most distinguishes fuel cells from conventional batteries is their ability to continuously produce energy without requiring recharging. Moreover, only water vapor, heat, and electricity are formed in fuel cells when hydrogen is employed as fuel. Fuel cells can produce very different strengths to power systems as large as a power station and as small as a laptop or electronic device. Therefore, this chapter investigates the operating principle of a fuel cell, the classification of fuel cells, and the basic properties of each fuel cell. © 2023 Elsevier Inc. All rights reserved.
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    Thermal modeling and performance assessment of a PEM fuel cell
    (Elsevier, 2023) Bayat, M.; Kayfeci, M.
    This chapter introduces a three-dimensional (3D) thermal model of a PEM fuel cell (PEMFC) to determine its performance characteristics and comprehensively discuss the mass transfer within the cell. In this study, a steady-state and isothermal model has been adopted to describe the multiphysics of a single-phase flow. In addition, the transport phenomena in the gas flow channels, gas diffusion layers (GDLs), and gas diffusion electrodes (GDEs), along with electrochemical currents in the GDLs, the GDEs, and the electrolyte membrane, have been considered. In this proposed model, the molar fractions of reactants and water along a single channel and the variation of electrolyte voltages, velocity profiles, and pressure gradients are analyzed and discussed for different operating temperatures from 323.15 to 353.15K. Accordingly, the maximum power density varies between 0.542 and 0.572W/cm2, whereas the optimum net output voltage varies between 0.537 and 0.581V in the same temperature range. © 2023 Elsevier Inc. All rights reserved.