# Optimization of the Battery Pack Heat Dissipation Structure of a Battery-Type Loader
## 4 Results and Discussion of Single-Factor Analysis
Comprehensive Analysis of the Effect of Air Outlet Size and Bulkhead Width on the Heat Dissipation Characteristics of Battery Packs  
Based on the best air outlet location being that of the Type IV battery pack, the comprehensive effects of the variation of air outlet size and bulkhead length on the heat dissipation characteristics of the battery pack were studied. Schematic diagrams of the partition gap and air outlet are shown in Figure 12.  
As shown in the figure, with other conditions kept unchanged, the comprehensive effects of different air outlet sizes and bulkhead lengths on the thermal characteristics of the battery pack were further analyzed by varying the partition gap width \(x\) and air outlet length \(y\) to optimize the heat dissipation effect of the battery pack. The value of \(x\) was set as a series of equal differences with the first term being 10 mm and the difference being 10 mm, while the value of \(y\) is set as a series of equal differences with the first term being 100 mm and the difference being 100 mm. The wind speed of the air inlet was taken as the maximum value of 3 m/s, while other parameters and conditions (e.g., the location of the air inlet) were kept unchanged. The simulation results are shown in Figure 13 below. As the battery pack usually has the best heat dissipation effect at the air inlet, the lowest temperature of the battery pack was distributed near the air inlet. The lowest temperature was 35.4 \({}^{\circ}\)C and was not affected by the length of the air outlet or the width of the gap of the partition. Therefore, the lowest temperature of the battery pack is not discussed below: only the maximum temperature, average temperature, and temperature difference  
Figure 11: Air flow line diagram in type IV battery pack. Figure 12: (**a**) Schematic diagram of the width of partition gap; and (**b**) schematic diagram of air outlet length. of the battery pack affected by the length of the air outlet and the width of the partition gap are discussed. Figure 13: (**a**) The maximum temperature variation curve of the battery pack; (**b**) the average temperature variation curve of the battery pack; and (**c**) temperature difference variation curve of the battery pack. As shown in Figure 13a, for the maximum temperature of the battery pack, the fluctuation of the maximum temperature of the battery pack is more drastic with a change in the width of the partition gap and the length of the air outlet. From the overall curve, the width of the partition gap had a greater effect on the maximum temperature of the battery, compared to the length of the air outlet. When the width of the partition gap was 10 mm and the length of the air outlet was 800 mm, the maximum temperature of the battery pack was 58.1 \({}^{\circ}\)C, which was the lowest temperature at that time. At the same time, when the width of the partition gap was 100 mm and the length of the air outlet was 800 mm, the maximum temperature of the battery pack was 62.8 \({}^{\circ}\)C, which was close to the overall maximum temperature of the battery pack. Considering the average temperature with the change in the width of the partition gap and the length of the air outlet, the fluctuation of the average temperature was not as drastic as that with the highest temperature and appeared to be gentler. Roughly speaking, compared with the length of the air outlet, the width of the partition gap had a greater effect on the average temperature of the battery. Aside from a few exceptions, the basic trend was that when the vent size was kept constant, the average temperature of the battery pack tended to increase gradually as the width of the partition gap increased. As the minimum temperature was basically the same, the variation of the temperature difference of the battery pack and the variation of the maximum temperature of the battery pack was basically the same with the changes in the width of the partition gap and the length of the air outlet.