Browsing by Author "Dilbaz, F"

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    Lithium-ion battery module performance improvements by using nanodiamond-FE3O4 water/ethylene glycol hybrid nanofluid and fins
    Dilbaz, F; Selimefendigil, F; Öztop, HF
    Control of heat released during charge/discharge processes of lithium-ion batteries is very important for the improvement of efficiency of lithium-ion batteries. In this study, the thermal performance of a 20 Ah rectangular type battery pack is analyzed with two different cooling fluids, namely water and nanodiamond-Fe3O4 water/ ethylene glycol (ND- Fe3O4 W/EG) hybrid nanofluid. The cooling system has 5 to 25 number of fins while the Reynolds number is taken between 100 and 800. The volume fraction of the nanoparticles is between 0 and 2% while the discharge rates of 3C, 4C and 5C are considered. The findings suggest that increasing the Reynolds number and the nanoparticle volume ratio improves the temperature distribution and lowers the maximum temperature in the battery pack. When compared to water with the same Re number, ND-Fe3O4 + W/EG hybrid nanofluid with 2% volume ratio at 800 Re number provides improvement of maximum temperature by 23.1% while 70.35% improvement in temperature difference is achieved. Using higher number of fins improves the performance. There is a reduction of 13.8% of the temperature difference in the battery pack with 25 fin model as compared to 5 fin model.
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    Comparisons of different cooling systems for thermal management of lithium-ion battery packs: Phase change material, nano-enhanced channel cooling and hybrid method
    Dilbaz, F; Selimefendigil, F; Öztop, HF
    Heat produced during the charging/discharging cycle must be dissipated for lithium-ion batteries to operate efficiently. Consequently, three distinct li-ion battery cooling systems were devised in this research, including phase-changing material (PCM), liquid-assisted, and hybrid, to allow lithium-ion batteries to run at the optimal operating temperature. To assess the efficiency of BTMS, the highest temperature and variation in temperature were examined. Without cooling system, simulations of the 20 Ah capacity battery pack were performed at various discharge rates (2C, 3C, and 4C). After that, an effective thermal management technique was identified by simulating PCM, liquid-assisted, and hybrid BTMS. The efficacy of PCM and BTMS was investigated at three different discharge rates. Water and Al2O3 nanofluid cooling medium thermal performance was investigated for liquid-supported BTMS at four distinct Reynolds numbers (Re) (250, 500, 750, and 1000), three distinct volume ratios (0.5 %, 1 %, and 2 %), and four distinct nanoparticle geometric shapes (Oblate spheroid, block, cylinder, and platelet). The influence of cooling channels on the thermal characteristics on PCM was investigated utilizing four various Re values and three distinct volume ratios, as well as the cooling effectiveness of hybrid BTMS. When the findings were analyzed, it emerged that hybrid BTMS improved the highest temperature by 28 %, while PCM and liquid-assisted cooling techniques enhanced peak temperature by 26 % and 27 %, correspondingly. However, when the temperature difference was analyzed, it was determined that only the hybrid and PCM reduced it to less than 5 degrees C, which is a suitable temperature difference. Paraffin can be cooled more efficiently by lowering the liquid stage distribution in the solid stage and the melting start time utilizing the hybrid cooling technique. Because of this, it has been determined that hybrid BTMS is the optimal cooling approach for the battery module.
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    Combined Utilization of Cylinder and Different Shaped Alumina Nanoparticles in the Base Fluid for the Effective Cooling System Design of Lithium-Ion Battery Packs
    Selimefendigil, F; Dilbaz, F; Öztop, H
    It is important to consider the thermal management of lithium-ion batteries to overcome their limitations in usage and improve their performance and life cycles. In this study, a novel cooling system for the thermal management of lithium-ion battery packs is proposed by using an inner cylinder in the cooling channel and different-shaped nanoparticles in the base fluid, which is used as the cooling medium. The performance improvements in a 20 Ah capacity battery are compared by using a water-boehmite alumina (AlOOH) nanofluid, considering cylinder-, brick-, and blade-shaped nanoparticles up to a solid volume fraction of 2%. The numerical analysis is conducted using the finite element method, and Reynolds numbers between 100 and 600 are considered. When the efficacy of the coolants utilized is compared, it is apparent that as the Reynolds number increases, both cooling media decrease the highest temperature and homogenize the temperatures in the battery. The utilization of the cylinder in the mini-channel results in a 2 degrees C temperature drop at Re = 600 as compared to the flat channel. A boehmite alumina nanofluid with a 2% volume fraction reduces the maximum temperature by 5.1% at Re = 200. When the shape effect of the nanofluid is examined, it is noted that the cylinder-shaped particle improves the temperature by 4.93% as compared to blade-shaped nanoparticles and 7.32% as compared to brick-shaped nanoparticles. Thus, the combined utilization of a nanofluid containing cylindrical-shaped nanoparticles as the cooling medium and a cylinder in the mini-channel of a battery thermal management system provides an effective cooling system for the thermal management of the battery pack. The outcomes of this work are helpful for further system design and optimization studies related to battery thermal management.