# Numerical Simulation on Thermoelectric Cooling of Core Power Devices in Air Conditioning
## 2 Simulations
**Finite element network division:** The division technique of the finite element network is to divide each domain into smaller-sized subdomains of various shapes, and these subdomains are called finite elements. The more nodes of the primitive, the smaller the calculation error, and the tiny parts can also be reflected, and the longer the calculation time is, too. Reasonable grid division can obtain more accurate calculation results. In this paper, triangles were used to divide the mesh unit, and the division results are shown in Figures 5 and 6. In this model, 196,16  
Figure 8 illustrates the steady-state temperature distribution of different components in the system under convectional air-cooling, and the whole process lasted about five minutes, as shown in Figure S3. As can be seen from Figure 8a, the power device had the highest temperature distribution among all system components, followed by the heat-sink fin and the air duct. Obviously, the heat was mainly concentrated on the power devices. The surface temperature of the power devices is proportional to their heat generation, and the heat-sink fins cannot effectively reduce the power device temperature. From Figure 8b,c, we can see that the maximum temperature of the high-heat-generating power device was 394.4 K, and the average temperature was 373.9 K, which exceeded its rated operating temperature of 368.1 K, while the maximum temperature of the low-power device was 371.6 K, and the average temperature was 358.2 K. Figure 8d shows the surface temperature distribution of the heat-sink fins. The temperature difference between the contact position of the power device and the heat-sink fins was not significant, which indicates that the uniform temperature performance of the heat-sink fins can meet the heat generation of the power device, so that most of the heat is transferred to the air through the heat-sink fins. The maximum surface temperature of the heat-sink fin was 363.8 K, and the average temperature was 348.5 K.  
Figure 8: Steady-state temperature distribution under air-cooling: (**a**) the overall system, (**b**) the high-power-consumption power devices, (**c**) the low-power-consumption power devices, and (**d**) the heat-sink fins. Figure 7: Airflow velocity distribution in the air duct. Then, we added a TEC beneath the power device that generates high levels of heat. The heat generated by the power device was actively carried to the heat-sink fins through the heat pump effect of the TEC. Consequently, the power device was temperature-controlled by active TEC cooling combined with the passive heat dissipation of the heat-sink fins. When the TEC operating current was 7.5 A, the steady-state temperature distribution of each component of the system was as shown in Figure 9, and the whole process lasted about eight minutes, as shown in Figure S4. As can be seen from Figure 9a, the combination of TEC active cooling with passive fin cooling resulted in a temperature distribution of each component in the system from high to low, namely the low-power devices without the TEC, the heat-sink fin, the air duct, and the high-power device with the TEC. The temperature distribution of the parts without the TEC was basically the same as that under single air-cooling, but the temperature of the high-power-consumption power device with the TEC was significantly lower. Additionally, the air temperature in the air duct was also different from that in the air-cooled heat sink because more heat was transferred to the air through convection heat transfer, causing the air temperature to become higher. The high-power-consumption power device had a maximum temperature of 331.8 K and an average temperature of 326.5 K (Figure 9b). The addition of the TEC resulted in a significant reduction in temperature, with the maximum temperature dropping by 62.6 K and the average temperature dropping by 47.4 K compared to single air-cooling, which demonstrates that TEC active cooling has a significant effect on the temperature field of the power device.