本研究針對電池模組中的產熱情形進行三維暫態熱流分析。首先利用實驗求得電池之比熱並推導出電池隨時間之產熱率，並將之應用於鋰離子電池模組中。爾後透過實驗數據觀察電池模組之PCB板其產熱對於模組的熱分佈有顯著影響，因此建立兩種形式的PCB板產熱方式應用於模擬中。第一種方法為收集PCB板上的6個溫度數據並假設PCB板為一塊狀系統來做均勻熱產生率。而第二種方法為將選定之時間點的溫度實驗數據代入Matlab中來做出擬合曲面並設置為邊界條件。此兩種方法都需由User-Defined Function來代入Ansys Fluent求解。後續由模擬驗證中可清楚看到模擬之數值隨著擬合曲面而改變，由此確立User Defined Function的正確性。模擬結果與設置於Cell Holder上的9個熱電偶數據做比對，可看到由於PCB板的產熱，對於此9點之溫度趨勢產生影響。由靠近PCB板的溫度最熱，且溫度隨著距離增加而遞減。此趨勢在兩組模擬中均可觀察到，不過在數值上與實驗數據有差距。PCB板的產熱也對於電池的溫度產生影響，使得整體電池的最大溫度差異在放電率0.6C時有4.6℃，而在放電率1C時有3.248℃。;The purpose of this study is to investigate the thermal-fluid field induced by the generation of heat during battery discharge in a Li-ion battery pack by 3D transient numerical simulations. The specific heat of the battery and the time-dependent heat generation of the battery were obtained based on experiments, and they were utilized as inputs for simulation settings. The experimental data further showed that heat generation of the PCB board was another significant heat in the battery package and had to be considered. Therefore, two methods concerning the heat source from the PCB energy dissipation were established. The first method was modeled by assuming the PCB was a lumped system and producing uniform heat based on the experimental data from the six thermocouples placed on the PCB plate. The second approach was to create time-dependent, curve-fitted surfaces as temperature boundary conditions from the measured temperature data by Matlab software. Both methods required the use of User-Defined Function to bring into Ansys Fluent. It was later validated that the numerical values varied with the curve-fitted faces and ensured the User-Defined Function was properly defined. The simulation results from both methods were compared with the measured temperatures obtained by the 9 thermocouples placed in the cell holder. It was found that the heat generation of the PCB plate had an impact on the temperature trend of these 9 points. The locations near the PCB plate had higher temperatures and the temperature gradually decreased as the distance with the PCB plate was increased. This trend was observed in both simulation methods, although their numerical values were different. The existence of heat generation of the PCB plate also affected the temperature distribution of the batteries, causing the maximum temperature difference of the batteries under 0.6C discharge rate to differ as high as 4.6℃. As for batteries under1C discharge rate the maximum temperature difference is 3.248℃.
