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: 18Citation - Scopus: 20Cold Plate Enabling Air and Liquid Cooling Simultaneously: Experimental Study for Battery Pack Thermal Management and Electronic Cooling(Elsevier, 2023) Coşkun, Turgay; Çetkin, ErdalThe temperature of cells varies greatly during dis/charge while their performance and lifetime are greatly affected by this fluctuation. Elevated temperatures may yield battery fire due to thermal runaway as well they accelerate ageing and capacity fade of cells. Thermal management systems are a necessity for electric vehicles to extend the lifetime of battery cells and eliminate any fire risks, especially for fast dis/charging applications. Here, we document a hybrid cold plate with a working fluid(s) of sole air or liquid as well as both of them. Hybridization of air and liquid cooling promises to minimize energy consumption requirements during a charge/ discharge cycle by combining the benefits of both thermal management strategies if energy management is controlled accordingly. The temperature of each cell can be kept below 30 degrees C with the proposed hybrid cooling heat exchanger, and the temperature difference between the cells is reduced by 30 % relative to liquid cooling. The maximum temperatures are decreased by 18 % and 3 % in hybrid cooling when compared to air and water cooling, respectively. Furthermore, a step function combining various discharge rates (1C and 3C) was employed in experiments to mimic a realistic situation, i.e. variable C-rate rather than constant. The results show that the temperature of the battery cells can be kept below 30 degrees C with air cooling for variable discharge rate and the effect of contact resistance should not be overlooked for liquid cooling. Furthermore, the possible use of the proposed hybrid cold plates is surveyed in the cooling of electronic devices which produce more and continuous heat than cells. Therefore, three resistance heaters with a capacity of 50W are used in experiments as well. The results show that the proposed cold plates could be used in both electronics cooling and battery thermal management with a control algorithm to switch between sole working fluid and combination modes which could be developed based on the results of this paper.Review Citation - WoS: 103Citation - Scopus: 136Digital Twin of Electric Vehicle Battery Systems: Comprehensive Review of the Use Cases, Requirements, and Platforms(Elsevier, 2023) Naseri, Farshid; Gil, S.; Barbu, C.; Jensen, A. C.; Larsen, P. G.; Gomes, Claudio; Çetkin, Erdal; Yarımca, GülşahTransportation electrification has been fueled by recent advancements in the technology and manufacturing of battery systems, but the industry yet is facing serious challenges that could be addressed using cutting-edge digital technologies. One such novel technology is based on the digital twining of battery systems. Digital twins (DTs) of batteries utilize advanced multi-layer models, artificial intelligence, advanced sensing units, Internet-of-Things technologies, and cloud computing techniques to provide a virtual live representation of the real battery system (the physical twin) to improve the performance, safety, and cost-effectiveness. Furthermore, they orchestrate the operation of the entire battery value chain offering great advantages, such as improving the economy of manufacturing, re-purposing, and recycling processes. In this context, various studies have been carried out discussing the DT applications and use cases from cloud-enabled battery management systems to the digitalization of battery testing. This work provides a comprehensive review of different possible use cases, key enabling technologies, and requirements for battery DTs. The review inclusively discusses the use cases, development/integration platforms, as well as hardware and software requirements for implementation of the battery DTs, including electrical topics related to the modeling and algorithmic approaches, software architec-tures, and digital platforms for DT development and integration. The existing challenges are identified and circumstances that will create enough value to justify these challenges, such as the added costs, are discussed.Article Citation - WoS: 30Citation - Scopus: 33Emergence of Elevated Battery Positioning in Air Cooled Battery Packs for Temperature Uniformity in Ultra-Fast Dis/Charging Applications(Elsevier, 2022) Göçmen, Sinan; Çetkin, ErdalPure electric vehicles (EVs) are gradually becoming major interest of research in worldwide. Battery cells in EV battery packs must be kept in between the desired operational temperature range (similar to 30 degrees C) and temperature should be homogeneous in packs to eliminate safety risks and prolong battery life. In this study, performance of a novel BTMS design was studied at various discharge conditions with fast and ultra-fast C-rate values. Cooling with natural convection exceeds desired operational temperature in the pack as well as forced air convection in Z-type manifold. Elevated battery positions yield flow resistance along the air channels in between battery cells to be uniform which yields flow rate sweeping the surface of each cell to be the same. Therefore, the maximum temperature in between cells decreases to less than 0.3K from the order of 12K. The temperature uniformity is essential for ageing and electrical resistance of cells to be homogeneous in a pack. In addition, heat transfer enhancement with various fin designs is documented as well as its effect on the temperature distribution. The accuracy of numerical studies is validated by experimental work. The results show that the peak temperature can be kept under the desired operational temperature with minimum deviation in the temperature difference for distinct operation conditions required for advanced electric vehicles (cars, airplanes, helicopters) with extreme charging and discharging capability.Article Citation - WoS: 75Citation - Scopus: 85Thermal Management System for Air-Cooled Battery Packs With Flow-Disturbing Structures(Elsevier, 2022) Şahin, R. Cagtay; Göçmen, Sinan; Çetkin, ErdalLithium-ion battery packs are preferred in electrical vehicles (EVs) due to their efficient and stable characteristics. Battery thermal management systems (BTMS) have vital importance in EVs to keep batteries in the desired temperature range to maximize performance and lifetime. BTMS with air cooling is simpler and lighter relative to competing methods; however, low thermal conductivity and heat capacity of air necessitate thermal performance and pressure drop adjustments. This work offers a novel design method for cylindrical cells by evaluating the effect of various baffles (cylindrical, triangular, diamond and winglet) on the cooling performance and pressure drop of an air-cooled battery module with 12 21700 cylindrical cells. Thermal characteristics are simulated by the electrochemical-thermal battery model, the P3D multiscale model (modelling parameters for a commercial 21700 cell are documented) in COMSOL Multiphysics 5.5 and their accuracy is validated by experiments. As a result, baffles reduce the maximum temperature and temperature difference by 5% (1.8 °C) and 40% (1.7 °C), respectively, consuming 3.5 times more power than the base design. Delta winglets offer the optimum solution, reducing the maximum temperature and temperature difference by 2% (0.6 °C) and 15% (0.7 °C), respectively, with a 44% (0.12 W) rise in parasitic power consumption.Article Citation - WoS: 30Citation - Scopus: 32Emergence of Asymmetric Straight and Branched Fins in Horizontally Oriented Latent Heat Thermal Energy Storage Units(Elsevier, 2022) Demirkıran, İsmail Gürkan; Rocha, Luiz Alberto Oliveirab; Çetkin, ErdalMobilized thermal energy storage units have a vital role in reducing energy consumption in buildings by enabling industrial waste heat to be used in buildings. High conductive fins can enhance the heat transfer performance of mobilized thermal energy storage tanks which suffer significantly from the low thermal conductivity of phase change materials. On the other hand, investment costs of the mobilized thermal energy storage tanks need to be decreased to compete with fossil fuel-driven systems in buildings. The present study numerically investigates the effect of innovative fin structures on the melting performance for fixed fin material volume to disable cost increase. Two-dimensional models with phase change were simulated for shell-and-tube heat exchangers. The shell geometry was designed sufficiently large to observe the melting growth of phase change material independent from shell walls within the given charging time. Straight and Branched type fin structures with the fin numbers of Nfin=2, 4, and 6 were simulated to uncover the effect of shape and length scale of fins on natural convection-driven melting. It was found that Straight fin type is more suited than Branched fins as they do not show significant melting enhancement with increased complexity and cost. The fin structures in all cases performed better when located at the top of the heat transfer fluid tube, even though the literature considers that top-located fins inhibit natural convection circulations. Varying the number of fins from (2-fin) to (4-fin) causes 15.8% increase in melting ratio, but further increase in the fin number (6-fin) reduces melting ratio below the (4-fin) case. Within (4-fin) structures located at the top, using distinct fin lengths yields melting ratio to increase 28.1%. Overall, the results show that heat transfer could be improved by varying the fin structure without increasing total fin volume and cost. The melting region growth shape with optimized fin structure forms the basis for the multitube arrangement of mobilized thermal energy storage units to enhance heat transfer performance with low cost.Article Citation - WoS: 16Citation - Scopus: 18Thermal and Electrical Characterization of an Electric Vehicle Battery Cell, an Experimental Investigation(Elsevier, 2022) Güngör, Şahin; Çetkin, Erdal; Lorente, SylvieThis paper documents the experimental characterization of a Li-ion battery cell during charging/discharging cyclic operations. The study of the battery cell is conducted in the absence of cooling aid system, and provides thermal and electrical insights. After describing the experimental set-up, the changes in temperature are presented and highlight the nonuniform distribution of the temperature on the battery cell surface. The findings indicate that the maximum temperature difference on the investigated battery cell surface may reach up to 11 C at 3C and 17 ⁰C at 5C, at the end of the discharge in the natural convection case. These changes in space come with temporal variations that are also documented. Voltage curves are provided during charging and discharging operations. The impact of the discharge rate, ambient temperature are then investigated together with the capacity fade after 500 cycles, and results showed that ventilation and low ambient temperatures allow to alleviate the battery capacity fade by 3%.Article Citation - WoS: 22Citation - Scopus: 22Emergence of Rectangular Shell Shape in Thermal Energy Storage Applications: Fitting Melted Phase Changing Material in a Fixed Space(Elsevier, 2021) Demirkıran, İsmail Gürkan; Çetkin, ErdalHere we document the effect of heat transfer fluid (HTF) tube position and shell shape on the melting time and sensible energy requirement for melting a phase change material (PCM) in a multitube latent heat thermal energy storage (LHTES) application. Tube location and shell shape are essential as the shape of the melted region, i.e. similar to the boundary layer, affects convective heat transfer performance. HTF tube total area is fixed in all cases to have the same amount of PCM. In order to eliminate the effect of heat transfer surface area variation, results of two- and four-tube configurations were compared within themselves. Liquid fraction, sensible enthalpy content, and latent/sensible enthalpy ratio relative to time were documented for two and four HTF configurations in various shell shape and tube locations. Results show that eccentric two tubes with rectangular shell decreases melting time and sensible energy requirement from 67 min to 32 min and from 161.8 kJ/kg to 136.3 kJ/kg for 72.3% liquid fraction, respectively, in comparison to the concentric tubes with the circular shell. When the number of HTF tubes increases to four, then the required melting time and sensible energy decrease 80% and 3.8%, respectively, for PCM to melt completely as the concentric tubes and circular shell is replaced with eccentric tubes and rectangular shell. Results of liquid fraction variation relative to time show that S-curve of melting becomes steeper if PCM distribution is such that the intersection of melted regions is delayed. Therefore, melted PCM regions could be packed into a shell that minimizes melting time and required sensible energy. Even rectangular shell shape increases the heat transfer surface (increased heat loss rate) because melting time has decreased greatly, total energy lost to the ambient from the surfaces of shell decreases. Eccentricity slows down the solidification process but due to increased heat loss rate from the surface, rectangular shell enables faster solidification than circular shell shape. There is a trade off in between solidification time and heat loss energy for rectangular channels which can be optimized by selecting proper insulation thickness. Overall, the results show that without any thermal conductivity enhancement (TCE) method, melting performance and latent heat storage capability can be significantly enhanced as decreasing the sensible heat storage by fitting the melted PCM regions into a fixed space for the applications where charging speed is lot faster than discharging.