## 6 Results and Discussions
### Effect of CO2 Permeance on Membrane Process Performance  
In the current paper, three different permeabilities (300, 1000, 3000 GPU) were studied to demonstrate the main influence of CO2 permeance on the membrane CO2 capture process. The impact of CO2 permeability was analyzed for all cases assumed based on process power consumption, CO2 capture efficiency and purity.  
To present part of Case 1 (one membrane unit) results obtained through different CO2 permeabilities, Table 5 declares particular parameters to reveal the capture process achievement at different CO2 permeabilities. It is comprehensible that increasing the permeability of CO2 helped to increase the carbon dioxide efficiency and purity by around 63% and 26%, respectively, with lower power consumption at 3 bar; 400,000 m\({}^{2}\) of CP1 and MSA1, respectively.  
At 80,000 m\({}^{2}\) of second membrane surface and 4 bar CP2, Table 6 exhibits certain optimal outcomes of Case 2 designed based on the analyzed CO2 permeabilities, where the CO2 capture rate variations of different compressor values regarding 300, 1000, and 3000 GPU are visibly shown. In contrast to Table 5, a greater CO2 purity was obtained at all the pressures, surfaces, and permeabilities assumed due to the usage of another membrane module with a lower surface area. The parameters presented below were selected only to demonstrate their impact on membrane performance.  
Figure 10: Different CO2 purity results regarding the three considered membranes.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**300 GPU**} & \multicolumn{3}{c}{**1000 GPU**} & \multicolumn{3}{c}{**3000 GPU**} \\ \hline MAS1 & m\({}^{2}\) & 400,000 & 800,000 & 400,000 & 800,000 & 400,000 & 800,000 & 400,000 & 800,000 \\ CP1 & bar & 3 & 7 & 3 & 7 & 3 & 7 & 3 & 7 & 3 & 7 \\ CO2 capture rate & \% & 26 & 65 & 45 & 89 & 50 & 93 & 73 & 99.7 & 70 & 99.5 & 88 & 99.9 \\ Power needed & MW & 130 & 286 & 171 & 370 & 153 & 314 & 197 & 383 & 171 & 321 & 211 & 385 \\ CO2 purity & \% & 57 & 56 & 53.2 & 46 & 71 & 64 & 64 & 48 & 77 & 65 & 68 & 48 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Different results of particular indicators for Case 1 at three permeabilities.  
Table 7 presents the best scores of 300, 1000, and 3000 GPU of CO\({}_{2}\) permeability for the same parameters assumed in Tables 5 and 6, in addition to 6 bar CP\({}_{3}\) and 8000 m\({}^{2}\) MSA\({}_{3}\) for Case 3 considered. The central object of the present research was obtained in this case where the carbon dioxide captured purity was 99.7% with almost 298 MW of electric energy requested, besides more than a 90% CO\({}_{2}\) removal rate: these results were achieved at 3000 GPU.  
The results obtained from Tables 5-7 show that improving membrane material with a higher CO\({}_{2}\) permeance helps to increase the affinity of that material toward CO\({}_{2}\) molecules, which increases the gas content absorbed via the membrane unit in enormous quantities; therefore, a higher CO\({}_{2}\) removal rate is obtained, see Figure 11a. On the other hand, the power consumption requirements for the membrane system showed a small increase with a high membrane permeability of CO\({}_{2}\), see Figure 11b. However, the figures demonstrate the significance of using a membrane material of high permeability to raise the efficiency of CO\({}_{2}\) removal with pretty much the same consumption of electricity. The figures were produced at three membrane stages (Case 3).