Optimization of cooling applications in lithium-polymer batteries

Lithium-polymer batteries are one of the battery types used in the aviation industry, especially in unmanned aerial vehicles. Like all battery systems, one of the most important problems encountered during charging or discharging of the battery is the heating problem, as well as the problems such as weight and low usage time compared to its weight. As a result of usage of lithium-polymer batteries in long term, the cell temperatures increase and the increasing cell temperatures damage the battery. For this reason, it is important for system safety and performance to transfer heat effectively and in a short time in lithium polymer batteries. In this study, cooling lithium-polymer batteries with air and increasing the capability of heat transfer from the surfaces of the battery models were examined. A cooling model was developed in unmanned aerial vehicles to decrease air resistance and keep battery temperatures in an optimum level, especially during take-off and landing phases. The battery models were produced using a three-dimensional printer, and the upper surfaces of these battery models were covered with aluminum fins of different heights, thicknesses and pitches. The visualization of the air velocities and flow structures around the battery models were carried out in the air tunnel with particle image velocimetry. Measurements performed with the particle image velocimetry were analyzed with different discharge rates and different air inlet temperatures in the computational fluid dynamics simulation software. The simulation results were compared with the experimental results, and the velocity distributions around battery and temperature dissipations were presented.