Numerical studies of lithium-ion battery thermal management systems using phase change materials and metal foams

摘要

This article investigates thermal management systems (TMS) of lithium-ion battery made from pure octadecane, pure gallium and octadecane-Al foam composite materials by numerical simulations. Porosity of the Al foam changes from 0.97 to 0.925 and 0.88. The numerical simulation is based on SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm, staggered grid, and temperature transforming model. Three different heat fluxes of 400, 600, and 800 W/m~2 at the left and right boundaries of the computational domain are considered to simulate the heat released from the battery. Different TMS's thicknesses have been studied. The time variations of battery surface temperatures are compared with different phase change materials (PCMs) to compare the effectivity of the TMS. Results show that the discharge time before the average battery surface temperature reaches above 60 ℃ increases with an increasing thickness (between 7.5 and 15 mm) of the TMS. The result with pure octadecane indicates that the discharge time is increased by 87 percent when the thickness of the TMS is increased from 7.5 mm to 15 mm. The surface temperature of the battery is more uniform and the discharge time is 4.7 times longer when gallium is used as the PCM, compared with those with octadecane for all thicknesses at the heat flux of 600 W/m~2 and thickness of 12.5 mm. Adding metal matrix of 0.88 porosity to the octadecane led to 7.3 times longer discharge time compared to the pure octadecane. It is also found that adding the Al foam to octadecane remarkably increases the uniformity of the battery surface temperature, i.e. the maximum temperature difference at the surface of the battery decreased from 25 ℃ with pure octadecane to 2 × 10~(-4) ℃ with octadecane-Al foam composite (0.88 porosity) after the battery discharges for 1000 s at 600 W/m~2 heat flux.