# Comprehensive Optimization of Air Quality in Kitchen Based on Auxiliary Evaluation Indicators
## 4 Optimization Analysis of Kitchen Air Quality
### Simulation Results of Different Working Conditions  
In this section, under identical power conditions (constant airflow rate and supply air temperature), five different top air supply angles were systematically designed to analyze their impact on the IAQ. The specific simulation conditions for each angle were detailed in Table 8.  
Figure 9 shows the ADPI values and corresponding fitting curves derived from the analysis of six different operating conditions. The results indicate that the lowest ADPI value for condition 5 was 28.48%, which was 16.64% higher than the original condition's lowest value of 11.84%, which effectively improved the airflow pattern. Additionally, with the top air supply system remaining active, the ADPI began to increase after 150 s. The optimal performance was observed in condition 5, where the ADPI reached approximately 80% after 270 s. This demonstrates that utilizing an effective top air supply could expedite the removal of hot, polluted air. Figure 8: Schematic diagram of top air supply outlet and optimization flowchart. (**a**) Schematic Diagram of Top Air Supply Outlet; (**b**) Optimization Flowchart. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Conditions**} & **Case 1 (Original** & & & & & \\  & **Condition** & **Case 2** & **Case 3** & **Case 4** & **Case 5** & **Case 6** \\ \hline Air Supply & & & & & & \\ Angle (deg) & 0 & 30 & 60 & 90 & 120 & 150 \\ \hline \hline \end{tabular} Note: The airflow rate is 2.16 m\({}^{3}\)/min, supply air temperature is 293 K.  
\end{table} 
Table 8: Simulation conditions. Human thermal sensation is a crucial indicator of indoor environmental quality. In this study, the PMV equation was compiled in C language and executed in Fluent via the User Defined Functions (UDF) interface to conduct a quantitative analysis during cooking. The calculation results were shown in Figure 10. The results indicate that the PMV value at the mouth breathing area increased over time, and peaked at 150 s when cooking ceased, influenced by the thermal plume generated during cooking. After cooking, as the effect of the thermal plume diminished, the comfortable airflow produced by the top air supply system significantly enhanced the airflow around the occupant and gradually reduced the PMV value at the mouth breathing area to a comfortable level below 1.5. Among them, it was found that condition 4 had the best performance. The PMV value at the forehead exhibited variability over time due to the combined effects of the cooking heat plume, the upper air supply system, and the heat plume generated by the body's own heat. In comparison, conditions 4 and 5 provided better thermal comfort. Figure 11 shows the CO\({}_{2}\) concentration distribution contour at the cross-section of x = 0.21 m and time of 150 s, under different conditions. The results demonstrate that activating the top air supply system could significantly increase the indoor CO\({}_{2}\) removal rate, and air supply angle could directly influence the spatial distribution of CO\({}_{2}\). In conditions 2 to 5, the airflow from the top air supply introduced fresh air to the lower part of the room, reduced CO\({}_{2}\) levels near the occupants and improved IAQ around the face area. At 150 s, the air quality in the room improved from a mildly polluted state to a  
Figure 10: Fitted plot of PMV over time for different conditions. Figure 9: Fitted scatter plot of ADPI over time for different conditions. clean air level, with polluted indoor air been efficiently expelled. According to the contour results, Condition 4 had the best performance. Figure 12 plots the time-domain fitting curves of the average CO\({}_{2}\) concentration in the breathing area and the average concentration in the room under different conditions.