Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 7Citation - Scopus: 7Hollowed and Perforated Fins in Latent Heat Storage Units for High-Temperature Hybrid Thermal Energy Storage Applications(Pergamon-elsevier Science Ltd, 2025) Demirkiran, Ismail Gurkan; Niedermeier, Klarissa; Cetkin, ErdalHigh-temperature thermal energy storage (TES) is essential for next-generation concentrated solar power (CSP) plants in order to ensure continuous energy supply. Hybridization of latent heat storage (LHS) and sensible heat storage (SHS) enhances energy density, thermal stability, and efficiency by leveraging the high storage capacity of phase change materials (PCMs) while reducing thermal ratcheting for sensible storage. This study focuses on a numerical analysis of a shell-and-tube LHS using sodium as heat transfer fluid (HTF). It examines the impact of hollowed and perforated fins to enhance effective heat exchange. Simulations were conducted in a 3D solution domain using ANSYS Fluent. The results show that fin removal rate and hole placement are crucial design factors. A 20% perforation rate in the Perforated fin-Middle(full) configuration maintains high heat transfer efficiency, reduces material costs, and increases PCM storage. In comparison to molten salts as HTFs, liquid metals exhibit effectively lower HTF outlet temperatures, which is vital for LHS-SHS integration. These findings provide valuable insights for optimizing high-temperature TES units in large-scale CSP applications.Article Citation - WoS: 1Citation - Scopus: 2Investigation of the Effects of Various Parameters on Wireless Power Transfer Efficiency(Elsevier Gmbh, 2025) Yilmaz, Mert; Cetkin, Erdal; Akca, HakanElectric vehicles have dominated the automotive market, especially in recent years. However, the charging problem that stresses drivers continues. Although conductive charging is an established technology, it still needs to meet user expectations fully. On the other hand, wireless charging technology attracts users' attention with dynamic charging features. Although this technology improves daily, efficiency is not at the desired level. In this study, a wireless power transfer system was designed for electric vehicles, and the factors affecting the charging efficiency were investigated. This system consists of an inverter, a compensation system, and a load. The efficiency of the system according to cable type, air gap, cooling, and pulse-width modulation parameters was observed through 40 experiments, each lasting 20 min. In addition to efficiency, the frequency behavior was also investigated. Experimental results were compared with models designed in MATLAB and ANSYS software. The average errors between the experimental and simulation results are 1.75, 2.03, 1.85, 1.58, and 2.00% for air gaps of 19-20, 55-56, 91-92, 127-128, and 145-146 mm, respectively. Power was transferred wirelessly with a minimum efficiency of 59.25% at a 145 mm air gap and a maximum efficiency of 85.74% at a 56 mm air gap in 300 W tests.Article Impact of Cooling Strategies and Cell Housing Materials on Lithium-Ion Battery Thermal Management Performance(Mdpi, 2025) Aydin, Sevgi; Çetkin, Erdal; Samancioglu, Umut Ege; Savci, Ismail Hakki; Yigit, Kadri Suleyman; Cetkin, ErdalThe transition to renewable energy sources from fossil fuels requires that the harvested energy be stored because of the intermittent nature of renewable sources. Thus, lithium-ion batteries have become a widely utilized power source in both daily life and industrial applications due to their high power output and long lifetime. In order to ensure the safe operation of these batteries at their desired power and capacities, it is crucial to implement a thermal management system (TMS) that effectively controls battery temperature. In this study, the thermal performance of a 1S14P lithium-ion battery module composed of cylindrical 18650 cells was compared for distinct cases of natural convection (no cooling), forced air convection, and phase change material (PCM) cooling. During the tests, the greatest temperatures were reached at a 2C discharge rate; the maximum module temperature reached was 55.4 degrees C under the natural convection condition, whereas forced air convection and PCM cooling reduced the maximum module temperature to 46.1 degrees C and 52.3 degrees C, respectively. In addition, contacting the battery module with an aluminum mass without using an active cooling element reduced the temperature to 53.4 degrees C. The polyamide battery housing (holder) used in the module limited the cooling performance. Thus, simulations on alternative materials document how the cooling efficiency can be increased.Article Citation - WoS: 1Citation - Scopus: 1High Accuracy and Applicability Battery Aging Models for Electric Vehicle Applications(Electrochemical Soc inc, 2025) Yarimca, Gulsah; Jensen, Anders Christian Solberg; Cetkin, ErdalBatteries have gained significant attention due to their numerous advantages in applications such as electric vehicles. One of the factors limiting industry adoption is the aging of batteries. The characteristics of battery aging vary depending on many factors such as battery type, electrochemical reactions and operating conditions. Here we document the comparison of semi-empirical aging models (SEM), highlighting limitations and challenges. In addition, four SEMs are proposed. The usability and compatibility of these models are evaluated using experimental data from various sources including the Horizon 2020 Helios Project. The optimized parameters of each model are documented via linear regression and genetic algorithms. The results show that the genetic algorithm approach provides higher accuracy in comparison to the linear regression. The documented SEMs reveal better prediction performance than the literature of calendar obsolescence with SEM-3 and 7 performing particularly well in predicting capacity loss for the Helios dataset with low errors, i.e. 0.43 and 0.79 RMSE, respectively. The range of RMSE values for model predictions across all the datasets ranges from 0.196 to 3.903. This study aims to document the accuracy of SEMs both from the literature and proposed in the paper relative to battery ageing data from distinct sources.Review Citation - WoS: 13Citation - Scopus: 18Review of Cell Level Battery (calendar and Cycling) Aging Models: Electric Vehicles(Mdpi, 2024) Yarimca, Gulsah; Cetkin, ErdalElectrochemical battery cells have been a focus of attention due to their numerous advantages in distinct applications recently, such as electric vehicles. A limiting factor for adaptation by the industry is related to the aging of batteries over time. Characteristics of battery aging vary depending on many factors such as battery type, electrochemical reactions, and operation conditions. Aging could be considered in two sections according to its type: calendar and cycling. We examine the stress factors affecting these two types of aging in detail under subheadings and review the battery aging literature with a comprehensive approach. This article presents a review of empirical and semi-empirical modeling techniques and aging studies, focusing on the trends observed between different studies and highlighting the limitations and challenges of the various models.Article Citation - WoS: 5Citation - Scopus: 5An Experimental and Comparative Study on Passive and Active Pcm Cooling of a Battery With/Out Copper Mesh and Investigation of Pcm Mixtures(Elsevier, 2024) Samancioglu, Umut Ege; Gocmen, Sinan; Madani, Seyed Saeed; Ziebert, Carlos; Nuno, Fernando; Huang, Jack; Cetkin, ErdalThe carbon emission contribution to global warming accelerated both research on and transition to electric vehicles (EVs). Drivers demand high power, fast acceleration and less charging times. All these demands require high C rate charging/discharging demands from batteries. The rate of heat generation is exponentially proportional to C rates which decreases battery lifetime and may lead to thermal runaway. However, a battery thermal management system decreases thermal runaway risk and decelerates battery degradation via controlling battery temperature. In this paper, we first document the thermal conductivity enhancement via copper foam into phase change material (PCM) domain to uncover their possible use in EV thermal management applications. Maximum 15.93 times increment is achieved with a specific copper foam. Then, physical properties and behaviors of distinct PCM mixtures are documented. Homogeneity of mixtures is associated with the chemistry of PCMs and the mixture melting point is proportional to the volume weighted average of melting temperatures. The results document that the PCM with relatively lower melting point is beneficial when end of discharge temperatures considered, except for high discharge rate of 2C. Temperature uniformity across the battery increases with relatively higher melting point PCM. Experiments also document that the amount of PCM volume lost via insertion of copper foam yields higher end of discharge temperatures. Overall, both PCM and copper foam enhances temperature homogeneity and their benefit becomes more sensible during drive cycles relative to continuous charge/discharge use cases.Article Citation - WoS: 2Citation - Scopus: 2Optimization of Y-Shaped Micro-Mixers With a Mixing Chamber for Increased Mixing Efficiency and Decreased Pressure Drop(Asme, 2024) Samancioglu, Umut Ege; Kosar, Ali; Cetkin, ErdalIn this study, Y-shaped micromixers with mixing chamber design optimized as rotation and chaotic advection in the fluid domain increase with the chamber. Motivated by the advantages of Y-shaped mixers, a parametric study was performed for inlet angles (alpha, beta), inlet channel eccentricities (x-ecc, z-ecc) and length scale ratios (L-1/L-2, D-1/D-2, and V-sp). z-eccentricity is introduced in addition to x-eccentricity to create a design that further enhances the swirl and chaotic advection inside mixing chamber for the first time. The results reveal that the maximum mixing efficiency can be achieved for Reynolds number of 81 and alpha, beta, x-ecc, z-ecc, D-1/D-2, and L-1/L-2 values of 210 degrees, 60 degrees, 20 mu m, 20 mu m, 1.8, and 4, respectively. In addition, the proposed Y-shaped micromixer leads to a lower pressure drop (at least 50% reduction for all Reynolds numbers) in comparison to competing design. The maximum reduction in pressure drop is 72% less than the curved-straight-curved (CSC) (Re = 81) with mixing efficiency of 88% and pressure drop of 9244.4 Pa. Overall, an outstanding mixing efficiency was offered over a wide range of Reynolds numbers with distinctly low pressure drop and a compact micromixer design, which could be beneficial for a wide variety of applications where volume and pumping power are limited.