## 3 Results
### Storage Tank Volume Optimization  
Up to this point in the study, the volumes of the three storage tanks have been assumed to be equal. The Taguchi design was applied once again to evaluate how different volume ratios affect the performance of the fuel station and to determine the optimal ratio. The control factors and their levels used in the analysis are listed in Table 5.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline  & \multicolumn{3}{c}{**Normalization**} & \multicolumn{3}{c}{**Gray Relational Coefficient**} & \multicolumn{1}{c}{**GRG**} & \multicolumn{1}{c}{**Order**} \\ \hline
**Sim. No** & **nVehicle** & **mAverage** & **WComp** & **nVehicle** & **mAverage** & **WComp** & & \\ \hline
1 & 0.42 & 1.00 & 0.07 & 0.46 & 1.00 & 0.35 & 0.45  
In the Taguchi design, two control factors were selected to define the tank volumes. The first is the ratio of LB volume to total volume (\(\overline{\
u}_{\text{low}}\)), given in Equation (1). The second is the ratio of MP volume to HP volume (\(\overline{\
u}_{\text{m/h}}\)), given in Equation (4), for the remaining volume. Each factor has three levels, resulting in nine cases (\(3^{2}=9\)). These levels are based on a total storage volume of 48 tanks, each with a 150 L capacity, leading to a total of 7200 L. The control factor values are designed to align with the L9 orthogonal array. For each of the nine cases, the number of vehicle tanks that can be filled in 24 h (\(n_{\text{vehicle}}\)), the average mass of gas accumulated in a vehicle tank (\(\text{m}_{\text{Average}}\)), and the work performed by the compressor per mass charged (\(\text{W}_{\text{Comp}}\)), are calculated. In these calculations, the pressure values that yielded the best results in previous analyses are used. The results are summarized in Table 10 under the column heading \"Results.\"  
Following this, S/N (signal-to-noise) ratios were calculated using the larger-is-better approach for \(n_{\text{Vehicle}}\) and \(\text{m}_{\text{Average}}\), while the smaller-is-better approach was applied for \(\text{W}_{\text{Comp}}\). The S/N ratio values for each output parameter are also presented in Table 10.  
Figure 14a illustrates the behavior of the S/N ratios calculated for \(n_{\text{Vehicle}}\) at the specified levels of the control factors. According to this figure, the maximum \(n_{\text{Vehicle}}\) of 231 is achieved when the ratio of LB volume to total volume (\(\overline{\
u}_{\text{low}}\)) is set to 0.25 and the ratio of MP volume to HP volume (\(\overline{\
u}_{\text{m/h}}\)) is set to 0.5. Figure 14: (**a**) S/N ratios for \(n_{\text{Vehicle}}\) at specified control factor levels during storage volume optimization; (**b**) S/N ratios of control factors for the average gas mass (\(\text{m}_{\text{Average}}\)) at specified control factor levels during storage volume optimization. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Control Factors and**} & \multicolumn{3}{c}{**Results**} & \multicolumn{3}{c}{**S/N Ratio**} \\ \cline{3-10}  & \multicolumn{2}{c}{**Levels**} & & & & & & & \\ \hline \multirow{2}{*}{**Sim. No**} & \(\overline{\
u}_{\text{low}}\) & \(\overline{\
u}_{\text{m/h}}\) & \(\mathbf{n}_{\text{Vehicle}}\) & \(\mathbf{m}_{\text{Average}}\) & \(\mathbf{W}_{\text{Comp}}\) & \(\mathbf{n}_{\text{Vehicle}}\) & \(\mathbf{m}_{\text{Average}}\) & \(\mathbf{W}_{\text{Comp}}\) \\  & & & & [kg] & [kWh/kg] & & [kg] & [kWh/kg] \\ \hline
1 & 0.25 & 0.5 & 231 & 9.511 & 0.200 & 47.272 & 19.564 & 13.989 \\
2 & 0.25 & 1 & 227 & 9.456 & 0.194 & 47.121 & 19.514 & 14.263 \\
3 & 0.25 & 2 & 229 & 9.358 & 0.185 & 47.197 & 19.424 & 14.638 \\
4 & 0.5 & 0.5 & 226 & 9.335 & 0.188 & 47.082 & 19.402 & 14.502 \\
5 & 0.5 & 1 & 224 & 9.290 & 0.184 & 47.005 & 19.360 & 14.708 \\
6 & 0.5 & 2 & 229 & 9.209 & 0.177 & 47.197 & 19.284 & 15.024 \\
7 & 0.75 & 0.5 & 231 & 9. Figure 14b presents the calculated S/N ratios of the control factors for the average gas mass (m\({}_{\text{Average}}\)) accumulated in the vehicle tank.