مجتبي صفدري

Li-ion batteries used in electric devices and vehicles suffer from their low soutable temperature range. So this probles raise an issue to manage their thermal caractristic. Using phase change material (PCM) has been proved as a promising way to overcome this problem. Studing a moving of the PCM interface and simulating this phenomena with numerical methods is one of the major problems beacause of its computational costs. In the first section of this thesis solving defferent types of phase change problems via novel super fast and accurate method called generalized differential quadrature has beem investigated. Results showed that this method can predict the behavior of the phase change problems with the accuracy of less than 0.2% compare with exact method. In the next part this method was used to simulate to predict the behavior of the phase change phenolmena in the long time duration. By using different type of PCMs surrounding battery it was reffered that CaCl2.6H2O has better performance than other materials in reducing the battery temperature when the period time is 40hr and less. an‎d after this time Capric Acid show better performance than others. In the second part of this thesis simulating of the battery thermal management systems was studied at higher level of implication. By investigating on different type of PCM containers around the battery it was concluded that as long as the liquid fraction of the system is less than 1 the cylindrical container shows better performance but since them acoording to better air flow distribution in the battery pack the rectangular container becomes superior. After this it was decided to optimize the gemometry and the air velocity inlet of the mentioned pack. After optimizing results depicted that to maintain the Area, maximum and average temperature of the batteries in the pack the material should be PEG-1500 and the thickness of the air gap, PCM thickness and air velocity inlet should be 4.76mm, 1.41mm and 1.98m/s.