Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Access Right: Embargoed AccessSubject: search.filters.subject.Electric vehicle

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 7
    Enhanced Temperature Uniformity With Minimized Pressure Drop in Electric Vehicle Battery Packs at Elevated C-Rates
    (Wiley, 2022) Güngör, Şahin; Çetkin, Erdal
    The trend of transition from fossil fuel to electrification in transportation is a result of no carbon emission produced by electric vehicles (EVs) during their daily operations. Furthermore, the global carbon footprint of EVs can be minimized if the electricity is generated from renewable sources such as wind and solar. On the other hand, there are some drawbacks of these vehicles such as charging time being very long and the mileage range of vehicles not at the desired level. Battery cells are being charged at relatively high C-rates to eliminate these problems, yet high current rates accelerate the aging of batteries and capacity losses due to the generated heat. Generated heat causes overheating, and excess temperature triggers degradation and thermal runaway risks. This paper uncovers how the battery pack temperature uniformity and strict thermal control can be achieved with heat transfer enhancement by conduction (cold plates) and convection (vascular channels). We aimed to reduce the energy consumption of the EV battery pack system while increasing the thermal performance. The impact of the thermal contact resistance is also considered for many realistic scenarios. The results indicate that an integrated system with cold plates and vascular channels satisfies the temperature uniformity requirement (over 81%) with comparatively less pumping power (∼72%) of advanced electric vehicles for relatively high C-rates. Furthermore, findings show the temperature level can increase up to 4°C as thermal contact resistance increases. The proposed cooling technique, which has low cost, easy application, and lower energy consumption superiorities, can be implemented in palpable EV battery packs.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 18
    Thermal and Electrical Characterization of an Electric Vehicle Battery Cell, an Experimental Investigation
    (Elsevier, 2022) Güngör, Şahin; Çetkin, Erdal; Lorente, Sylvie
    This 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: 83
    Citation - Scopus: 95
    Canopy-To Liquid Cooling for the Thermal Management of Lithium-Ion Batteries, a Constructal Approach
    (Elsevier Ltd., 2022) Güngör, Şahin; Çetkin, Erdal; Lorente, Sylvie
    With the growing interest on electric vehicles comes the question of the thermal management of their battery pack. In this work, we propose a thermally efficient solution consisting in inserting between the cells a liquid cooling system based on constructal canopy-to-canopy architectures. In such systems, the cooling fluid is driven from a trunk channel to perpendicular branches that make the tree canopy. An opposite tree collects the liquid in such a way that the two trees match canopy-to-canopy. The configuration of the cooling solution is predicted following the constructal methodology, leading to the choice of the hydraulic diameter ratios. We show that such configurations allow extracting most of the non-uniformly generated heat by the battery cell during the discharging phase, while using a small mass flow rate.