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Öğe 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.Öğe Futuristic methods of electronics cooling(Elsevier, 2023) Uysal, A.; Keçebas, A.; Kayfeci, M.Power density for high-performance chips has recently increased due to advancements in semiconductors, other mini- and micro-scale electronic technologies, and continued miniaturization. Heat is generated when the current passes over a resistance, and internal losses are unavoidable. Electronic devices produce heat this way while working. This heat needs to be taken from electronic devices due to its effect on their performance. The fault ratio on electronic devices increases exponentially as the temperature increases. That is how high operation temperature occurs from heat production on electronic devices that are not controlled and designed to cause safety and performance decreases. This reality is to make it necessary for heat transfer, namely, developing cooling systems and new investigations, and to increase the importance of thermal control on the operation and design parameters of electronic devices day by day. In this chapter electronic device cooling methods are classified as advanced cooling technologies (active and passive cooling methods) with the goal of guiding future research while representing current application areas. © 2023 Elsevier Inc. All rights reserved.Öğe Introduction to solar panels(Elsevier, 2023) Karaagaç, M.O.; Ergün, A.; Arslan, O.; Kayfeci, M.Decarbonization has gained global importance in order to reduce climate change that is mainly caused by the usage of fossil fuels. Renewable energy sources have the potential to reduce carbon emissions. For this purpose, the energy sector has focused on cost-competitive solar panel technologies in recent years. Solar panels are systems made of semiconductor materials that convert the solar radiation coming to their surfaces into electrical energy. The fact that solar energy is an inexhaustible resource and is free in abundance is shown as the most economical system compared to traditional energy sources. Solar energy has an important share when considering the electricity obtained from renewable energy sources in the last decade. In addition, when the efficiency of PV technologies increases and their costs decrease, the use of these systems will become more widespread. Since it provides sustainable production and reduces CO2 emissions, solar panels can play an important role in meeting the national energy need. In this chapter, the history of solar panels, semiconductor materials, solar cells, PV technologies, the global energy situation, and their place in renewable energy sources are shown in the overview. © 2023 Elsevier Inc. All rights reserved.Öğe Liquid-based solar panel cooling and PV/T systems(Elsevier, 2023) Ergün, A.; Kayfeci, M.; Karaagaç, M.O.Solar panels (also called PV panels) have been widely used in recent years to generate electricity from solar energy. One of the biggest disadvantages of PV panels is their low efficiency. In general, the efficiency of a PV panel varies between 15% and 20%. The temperature increase in PV panels is the most important parameter that causes their efficiency to decrease. Each 1°C increase in temperature causes approximately 0.45%–0.6% efficiency decrease. For this reason, cooling of PV panels increases their efficiency. Liquid-based cooling processes are frequently used for the water cooling process. But recent years researchers are examining air, oils, water, and water/nanofluids dispersions. In this chapter, liquid-based cooling of PV panels will be examined in detail. New studies in this field will be given with examples and developments in photovoltaic thermal (PV/T) applications will be mentioned. © 2023 Elsevier Inc. All rights reserved.Öğe Solar panel cooling using hybrid cooling systems(Elsevier, 2023) Yildiz, G.; Karaagaç, M.O.; Ergün, A.; Kayfeci, M.Photovoltaic (PV) panels are systems that convert the energy from the sun into electrical energy. A large part of the energy coming to the PV panel is converted into heat, causing the panel temperature to increase and the electrical efficiency to decrease. There are many benefits of cooling the panel to increase the performance and PV panel’s controllability. By removing the heat from the panel, the efficiency of the panel rises and the heat received is used as useful heat. In addition, the cooling of the panels also extends the panel life. The heat produced by the PV panels can cause an increase in the cell temperature above 50°C, and this situation causes a decrease in electrical efficiency (0.4% per 1°C for monocrystalline). Photovoltaic thermal (PVT) panels have been developed to cool the PV panels, and cooling process is carried out by passing water or air behind the panel. This section focuses on the different hybrid cooling techniques used in PVT panels and the effects of these techniques on performance. © 2023 Elsevier Inc. All rights reserved.Öğe 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.
