# Optimization of the Battery Pack Heat Dissipation Structure of a Battery-Type Loader
## 4 Results and Discussion of Single-Factor Analysis  
Analysis of the Influence of the Outlet Position on the Heat Dissipation Characteristics of the Battery Pack  
To ensure that the battery pack still has a serpentine air duct, the air outlet position was kept within the range of the third layer of the battery pack and moved. Keeping the other structures of the battery pack unchanged, four different air outlet location schemes were proposed as shown in Figure 6, where 1 denotes the air inlet and 2 denotes the air outlet. We developed models and conducted simulations according to these air outlet schemes for the battery pack. The inlet wind speed was set to 1 m/s, 2 m/s, or 3 m/s, and other conditions were kept constant. In this way, we obtained battery pack temperature cloud diagrams for the four packs, as shown in Figures 7-10:  
As the air outlets of the four battery packs were all located at the third layer and other structural parameters remained unchanged, the temperature of the batteries in the first and second layers did not change considerably compared with that in the third layer. Therefore, we only compare the temperatures of the battery packs in the third layer. Figure 6: Schematic diagrams of the battery pack air outlet locations: (**a**) type I battery pack; (**b**) type II battery pack; (**c**) type III battery pack; and (**d**) type IV battery pack. Figure 7: Temperature cloud diagrams for type I battery pack under different inlet wind speeds: (**a**) 1 m/s; (**b**) 2 m/s; and (**c**) 2 m/s. As can be seen from Figures 7-10, different air outlet locations led to different heat dissipation effects in the battery packs. Among the four outlet positions, regardless of whether the inlet wind speed was 1 m/s, 2 m/s, or 3 m/s, the heat dissipation effect of type I and II packs was the worst, and the highest temperatures were observed in the third layer of the battery pack in these models. The heat dissipation effect of the type III pack was better, but the highest temperature of the third layer at the outlet position of the type IV pack was the lowest; therefore, the heat dissipation effect of this type of battery pack was the best. To explore the specific reasons for the heat dissipation effect of the type IV battery pack, the airflow line inside the type IV battery pack was analyzed, as shown in Figure 11.  
In the type IV battery pack, when the air flows to the third layer, it is forced to flow to the left and right sides of the third layer due to blockage of the wall behind, which greatly increases the turbulence effect of the air and leads to the best heat dissipation effect. As a result, the temperature of the batteries in the rear rows of the third layer was the lowest when compared to that in the other schemes. Therefore, the air outlet location in the following mainly adopts the type IV battery pack scheme. Figure 8: Temperature cloud diagrams for type II battery pack under different inlet wind speeds: (a) 1 m/s; (b) 2 m/s; and (c) 2 m/s. Figure 10: Temperature cloud diagrams for type IV battery pack under different inlet wind speeds: (a) 1 m/s; (b) 2 m/s; and (c) 2 m/s. Figure 9: Temperature cloud diagrams for type III battery pack under different inlet wind speeds: (a) 1 m/s; (b) 2 m/s; and (c) 2 m/s. However, for the battery pack as a whole, no matter which of the above-mentioned battery pack solutions was selected, only the temperature of the battery pack in the third layer changed significantly, and very high temperatures were still maintained in the first and second layers; even when the air velocity at the air inlet reached a maximum of 3 m/s, the maximum temperature in the battery pack still reached 64.7 \({}^{\circ}\)C. Obviously, the temperature does not meet the operating temperature requirements of the battery pack; therefore, further study of the influence of other structural parts of the battery pack on its thermal characteristics is needed.