Elektrikli araçlarda kullanılan lityum iyon akü paketleri için termal yönetim sistemi tasarımı

Lithium ion batteries are a normally used kind of rechargeable batteries as a result of their high specific energy and power. Expanding considerations have been paid to rechargeable Li-ion batteries with the developing popularity of electric vehicles and hybrid electric vehicle. However, safety problems, high cost, and poor performance in low ambient temperatures and high current rates are big obstacles for commercially utilization of these batteries. Most of the mentioned limitations could be eliminated by proper thermal management. Temperature profile of the Li-ion cells has noteworthy impacts on the performance, safety, and cycle life of the battery. That is the reason little temperature gradient can prompt incredible loss in the performance of battery packs. Lately, various analysts recommend new procedures to suggest a superior thermal management on Li-ion batteries. Keeping the battery cells in an optimum range is the primary goal of battery thermal management. In the first part of the study, a 3D model with new multilayer approach was developed to study the electrochemical-thermal behavior of the high capacity pouch type Lithium ion battery cells. In this approach, the 1D electrochemical module was coupled with the 3D thermal module using the COMSOL program which solves the differential equations numerically by finite element method (FEM). The developed Electrochemical-Thermal model was validated with the experimental measurements. The developed model was used to study the effects of multilayer structure and the number of electrodes on thermal behavior of the batteries for the first time in the literature. Then, the effects of cell dimensions and configuration were investigated on the temperature rise and nonuniformity of the battery cells. In the second part, an air-based and a water-based thermal management system were developed, and the cooling performance of them were optimized. As cooling system, aluminum plates with mini-channel system was designed to a single-cell and battery packs. Design parameters, for example, channel number and width, inlet flow rate, and cooling material were optimized. As cooling material, water- and air-cooling performances were compared. Pressure drop and velocity profiles inside the channels were illustrated. Both internal and external temperature profiles of a single cell and battery packs were investigated with and without cooling systems. In the last part, the optimized cooling systems were applied on the developed 4S1P battery modules. The needed inlet flow rates and power consumption values were calculated to keep the battery pack in an optimal operation temperature range (10-40 °C). The outcomes of this work showed that using upgraded mini-channel cooling plates adequately controls the temperature level and uniformity of the single cells and battery packs. With increasing the inlet flow rate, cooling efficiency can be as high as 60%.