## 3 Results and Analysis of the Filed Measurements
### Exhaust Fume System
#### 3.4.2 Air Velocity and Airflow Rate
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \
\begin{tabular}{c} **Measuring** \\ **Points** \\ \end{tabular} & \multicolumn{3}{c}{**Capture Point**} & \multicolumn{3}{c}{**Hood Face**} & \multicolumn{3}{c}{**Air Inlet in the Hood**} & \multicolumn{3}{c}{**Natural Makeup**} \\  & **1\({}^{\bf 1}\)** & **1\({}^{\bf 2}\)** & **1\({}^{\bf 3}\)** & **1\({}^{\bf 4}\)** & **1\({}^{\bf 5}\)** & **3** & **4\({}^{\bf 1}\)** & **4\({}^{\bf 2}\)** & **4\({}^{\bf 3}\)** & **9\({}^{\bf 1}\)** & **9\({}^{\bf 2}\)** \\ \hline
\begin{tabular}{c} **Standard** \\ **Value** \\ \end{tabular} & \multicolumn{3}{c}{**0.25–0.5 m/s [40]**} & \multicolumn{3}{c}{\(\geq\)**0.5 m/s [20]**} & \multicolumn{3}{c}{**4–5 m/s [20]**} & \multicolumn{3}{c}{\(\leq\)**1 m/s [20]**} \\ \hline
30-Apr & 0.55 & 0.66 & 0.68 & 0.47 & 0.17 & 0.35 & 11.41 & 9.10 & 7.00 & 0.66 & 0.21 \\ \(\pm\)U & 0.06 & 0.07 & 0.07 & 0.06 & 0.07 & 0.07 & 0.25 & 0.18 & 0.14 & 0.06 & 0.01 \\ 7-May & 0.50 & 0.57 & 0.63 & 0.55 & 0.21 & 0.40 & 12.86 & 8.77 & 6.73 & 0.67 & 0.19 \\ \(\pm\)U & 0.06 & 0.06 & 0.06 & 0.06 & 0.06 & 0.06 & 0.17 & 0.11 & 0.13 & 0.06 & 0.06 \\ 10-Jun & 0.53 & 0.46 & 0.45 & 0.52 & 0.36 & 0.44 & 11.90 & 8.21 & 7.06 & 0.70 & 0.20 \\ \(\pm\)U & 0.09 & 0.07 & 0.06 & 0.07 & 0.06 & 0.06 & 0.15 & 0.15 & 0.08 & 0.06 & 0.06 \\ 1-Jul & 0.43 & 0.45 & 0.43 & 0.46 & 0.29 & 0.40 & 12.09 & 8.39 & 6.73 & 0.78 & 0.31 \\ \(\pm\)U & 0.06 & 0.07 & 0.08 & 0.06 & 0.07 & 0.06 & 0.18 & 0.22 & 0.08 & 0.06 & 0.06 \\ 10-Jul & 0.52 & 0.46 & 0.55 & 0.52 & 0.12 & 0.35 & 11.78 & 8.71 & 6.95 & 0.57 & 0.32 \\ \(\pm\)U & 0.06 & 0.06 & 0.07 & 0.06 & 0.06 & 0.06 & 0.20 & 0.29 & 0.10 & 0.06 & 0.06 \\ 1-Aug & 0.54 & 0.40 & 0.58 & 0.50 & 0.11 & 0.35 & 11.87 & 8.74 & 6.98 & 0.64 & 0.34 \\ \(\pm\)U & 0.06 & 0.06 & 0.07 & 0.07 & 0.06 & 0.06 & 0.14 & 0.19 & 0.17 & 0.06 & 0.06 \\ 14-Aug & 0.52 & 0.51 & 0.50 & 0.52 & 0.22 & 0.35 & 12.04 & 8.56 & 7.34 & 0.70 & 0.31 \\ \(\pm\)U & 0.06 & 0.06 & 0.06 & 0.06 & 0.06 & 0.06 & 0.21 & 0.17 & 0.10 & 0.06 & 0.06 \\ 30-Aug & 0.48 & 0.53 & 0.51 & 0.46 & 0.19 & 0.35 & 11.98 & 9.04 & 6.35 & 0.69 & 0.31 \\ \(\pm\)U & 0.06 & 0.06 & 0.07 & 0.09 & 0.06 & 0.06 & 0.15 & 0.14 & 0.13 & 0.06 & 0.06 \\ 11-Sep & 0.53 & 0.46 & 0.42 & 0.42 & 0.22 & 0.36 & 11.95 & 8.69 & 6.60 & 0.73 & 0.22 \\ \(\pm\)U & 0.09 & 0.07 & 0.06 & 0.06 & 0.06 & 0.06 & 0.17 & 0.09 & 0.20 & 0.06 & 0.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Air velocity at each measuring point of the oil fume exhaust system. Figure 12: The cloud diagram of air velocity of the hood face. where: \(\mathrm{L}_{1}\) is the exhaust airflow rate, \(\mathrm{m}^{3}/\mathrm{h};1000\) is the empirical coefficient, \(\mathrm{m}/\mathrm{h}\); \(P\) is the perimeter of the exhaust hood (excluding the side against the wall), \(\mathrm{m};H\) is the distance between the hood face and the stoves surface, \(\mathrm{m}\). \[\mathrm{L}_{2}=3600\times 0.5\times\mathrm{A} \tag{10}\]  
where: \(\mathrm{L}_{2}\) is the exhaust airflow rate, \(\mathrm{m}^{3}/\mathrm{h}\); \(\mathrm{A}\) is the area of hood face, \(\mathrm{m}^{2}\)  
According to Formulas (8)-(10), the minimum exhaust airflow rate of this kitchen was 12312 \(\mathrm{m}^{3}/\mathrm{h}\). The makeup airflow rate should be 80%-90% of the exhaust airflow rate [2]. From Figure 13, we can find that the ratio of makeup airflow rate to exhaust airflow rate is between 76.11-94.24%, which is consistent with the standard value. However, the exhaust airflow rate of this kitchen is lower than the minimum value, which may lead to fumes overflowing from the exhaust hood during cooking.