## 3 Result
### Sensitivity Analysis
However, this topic will not be discussed in this study as additional analysis is required to re-engineer the process. Figure 6: Mole fraction at the outlet of the steam reformer and the efficiency of the fuel processor according to the temperature of the steam reformer. (S/C = 3, T\({}_{\text{HTS}}\) = 400 \({}^{\circ}\)C, and T\({}_{\text{LTS}}\) = 200 \({}^{\circ}\)C). Figure 7: Mole fraction at the outlet of the HTS and efficiency of the fuel processor according to the temperature of the HTS. (S/C = 3, T\({}_{\text{SR}}\) = 700 \({}^{\circ}\)C, and T\({}_{\text{LTS}}\) = 200 \({}^{\circ}\)C). As shown in Figure 9 and Table 4, the thermal efficiency of the fuel processor increases as the S/C ratio increases at steam reformer temperatures below 650 \({}^{\circ}\)C. As the steam reformer temperature increases, the thermal efficiency of the fuel processor increases. However, the thermal efficiency according to the S/C ratio seems to have a maximum point, according to the S/C ratio, at a temperature of 650 \({}^{\circ}\)C or higher in the steam reformer. At a steam reformer temperature of 650 \({}^{\circ}\)C, the highest efficiency was 81.81% at an S/C ratio of 4, but at a temperature of 700 \({}^{\circ}\)C or higher, the highest efficiency was obtained at an S/C ratio of 3. At a reformer temperature of 700 \({}^{\circ}\)C or lower, the highest thermal efficiency of 86.36% was obtained at an S/C ratio of 3. At higher temperatures, the conversion of natural gas to hydrogen increases and more natural gas enters the burner to provide heat to the reactants (natural gas and water) to produce the maximum thermal efficiency at different S/C ratios (and temperatures). Figure 10 shows the conversion of natural gas according to the S/C ratio and temperature of the steam reformer. The conversion of natural gas to hydrogen is calculated based on the molar flow rate of natural gas entering and leaving the steam reformer and indicates the degree of reaction. The amount of heat required to bring the water temperature to the operating temperature of the steam reformer at various S/C ratios and temperatures is  
Figure 8: Mole fraction at the outlet of the LTS and efficiency of the fuel processor according to the temperature of the LTS. (S/C = 3, TSR = 700 \({}^{\circ}\)C, and T\({}_{\rm HTS}\) = 400 \({}^{\circ}\)C). Figure 9: Comparison of the efficiency of the fuel processor according to the temperature of the steam reformer and S/C ratio. shown in Figure 11. Since a larger amount of water is supplied to the system at a high S/C ratio, the amount of heat required is increased according to the increase in the S/C ratio. On the other hand, since the natural gas conversion is more than 95% at 700 \({}^{\circ}\)C and an S/C ratio of 3, the increase in the hydrogen flow rate produced by increasing the S/C ratio at a temperature of 700 \({}^{\circ}\)C and higher is inevitably small. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline S/C Ratio & \(\mathbf{T_{SR}}\) (\({}^{\circ}\)C) & **500** & **600** & **650** & **700** & **800** & **900** \\ \hline
1 & 21.88 & 42.64 & 50.19 & 55.37 & 60.93 & 62.38 \\
2 & 32.32 & 59.54 & 73.50 & 81.85 & 85.60 & 85.93 \\
3 & 39.78 & 68.52 & 80.31 & **86.36** & **88.94** & **89.15** \\
4 & 45.39 & 73.25 & **81.81** & 85.14 & 86.32 & 86.41 \\
5 & 50.58 & **75.31** & 81.12 & 82.95 & 83.56 & 83.61 \\ \hline \end{tabular}
\end{table} 
Table 4: Thermal efficiency of the fuel processor corresponding to the steam reformer temperature and S/C ratio. (The bold and border represent the maximum efficiency at the same temperature.) Figure 11: The energy required to heat water according to the S/C ratio and temperature of the steam reformer. Figure 10: Conversion of natural gas according to the temperature of the steam reformer and S/C ratio.