Comparison of Experimental and Simulation Results of Cooling Performance by Using Heat Pipe Combined With Forced Air Cooling for Lithium-Ion Batteries

In this work, the battery thermal management system (BTMS) using heat pipe and forced air cooling for NMC lithium-ion batteries was designed. The effect of air velocity on cooling performance was studied and compared between experimental and simulation results. All studies were conducted on lithium nickel manganese cobalt oxide (NMC) pouch cells with a 20 Ah capacity in seven series connections, under air velocities of 6.3, 9.5, and 12.7 m/s, with 4C discharge rates, at room temperature 22°C. The cooling performance was considered from two variables: the maximum temperature of the battery in the pack (T_max) and the maximum temperature difference of the battery in the pack (▵T_max). Both the experimental and simulation results indicated that increasing the air velocity has the effect of decreasing the T_max, while the ▵T_max did not differ significantly. The appropriated air velocity was 9.5 m/s. The behaviour from the simulation method was consistent with the experimental method, but the magnitude of the temperature fluctuations was still very large. At an air velocity of 9.5 m/s, T_max from simulation was only 33.1°C, while the experimental result was 44.3°C. The ▵T_max from the simulation was only 1.9°C, while the experimental result was 11.1°C. The main reason for the large difference was the properties of the materials used in the experiments, including batteries and heat pipes.