Yazar "Erhan, Koray" seçeneğine göre listele

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    A novel cost-efficient daylight-based lighting system for public buildings: design and implementation
    (Znack Publishing House, 2020) Ayaz, Murat; Yücel, Uğur; Erhan, Koray; Özdemir, Engin
    In this study, design and implementation of a new cost-efficient daylight-based lighting control system is proposed to provide energy saving in a public building with a conventional lighting system. Energy gain recovery and regional daylight utilization coefficients are obtained by conducting daylight measurements in all indoor spaces of the building where the proposed lighting system will be applied. Daylight value is continuously transferred to the control system through the pyranometer placed outside and the need for artificial lighting is calculated by using sectional daylight utilization coefficients. Thereby, maximum benefit from daylight is realized when unnecessary energy consumption for artificial lighting is reduced. Experimental measurement results show that the proposed daylight-based lighting control system provides an average energy efficiency of the building at the level of 60 %. Additionally, the required investment, such as operating cost and payback period for converting an existing conventional lighting system into the proposed system, are discussed in detail. Cost analysis shows that the payback period of the proposed system can be reduced by 5 years compared to the conventional system.
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    High-speed kinetic energy storage system development and ANSYS analysis of hybrid multi-layered rotor structure
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Yangöz, Cenk; Erhan, Koray
    Flywheel energy storage systems (FESSs) can reach much higher speeds with the development of technology. This is possible with the development of composite materials. In this context, a study is being carried out to increase the performance of the FESS, which is especially used in leading fields, such as electric power grids, the military, aviation, space and automotive. In this study, a flywheel design and analysis with a hybrid (multi-layered) rotor structure are carried out for situations, where the cost and weight are desired to be kept low despite high-speed requirements. The performance values of solid steel, solid titanium, and solid carbon composite flywheels are compared with flywheels made of different thicknesses of carbon composite on steel and different thicknesses of carbon composite materials on titanium. This study reveals that wrapping carbon composite material around metal in varying thicknesses led to an increase of approximately 10-46% in the maximum rotational velocity of the flywheel. Consequently, despite a 33-42% reduction in system mass and constant system volume, the stored energy was enhanced by 10-23%. It was determined that the energy density of the carbon-layered FESS increased by 100% for the steel core and by 65% for the titanium core.
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    Prototype production and comparative analysis of high-speed flywheel energy storage systems during regenerative braking in hybrid and electric vehicles
    (Elsevier, 2021) Erhan, Koray; Özdemir, Engin
    In conventional EVs and HEVs, only a small part of the vehicle's kinetic energy can be usefully stored during deceleration. Generally, this storage process can be done by providing energy flow to the main battery of the vehicle. Since batteries work with a chemical reaction, they are not suitable for fast charging and discharging required for regenerative braking. In this case, a fast storage system is needed to store the regenerative braking energy in a short time. As a solution, the flywheel energy storage system (FESS) can be offered. In the literature, power transmission of vehicles with integrated FESS is provided by mechanical systems (CVT FESS). These systems are heavy, high cost, large volume, and occupy the rear axle of the vehicle. In the proposed system, a purely electrical power transmission is proposed to store the kinetic energy of the vehicle in FESS. In developed topology, the traction machine of the vehicle is also used as a generator, and the recuperation energy is stored in the electrically driven (M/G) FESS. As a result of the experimental studies, a minimum of 56% energy recovery efficiency was obtained. In addition, it has been shown that the developed system is 30% lighter, occupies 60% less space in volume, is at least 50% more cost-effective, maintenance-free, and has fewer moving parts compared to the CVT FESS. As a result, the addition of a fast-response secondary energy storage system to the electric vehicle battery contributes to the increase in efficiency.