## 3 Results and Discussion
### Case Study B: Hybridization with GT (Gas Turbine) Fed with External Fuel  
This case study considers heat recovery in exhaust gases from a GT (fed with external fuel) to heat up the feed stream to supercritical temperatures. As in case study A, the configuration plant for this case corresponds to that shown in Figure 3, but replacing the ICE by a GT. The selection of the GT model is based on the energy required to heat the feed stream. For each operating conditions, GT will generate an exhaust gas flowrate with a maximum temperature of 530 \({}^{\circ}\)C [55]. This stream is used as 'hot fluid' to increase the feed stream ('cold fluid') temperature up to the reactor inlet temperature that ranges from 450 \({}^{\circ}\)C to 520 \({}^{\circ}\)C since a minimum pinch point temperature of 10 \({}^{\circ}\)C is considered in the preheater. Moreover, taking into account the performance of a GT in combined heat and power mode, the available mechanical power is also produced for electricity generation [56]. For this case, in contrast to the previous one, the cold fluid (feed stream) is heated in a single preheater from ambient temperature to 520 \({}^{\circ}\)C. The countercurrent hot fluid in the heat exchanger is composed of a variable flowrate of exhaust gases coming from GT with a maximum temperature of 530 \({}^{\circ}\)C. The outlet temperature in the hot fluid stream remains in a range from 97 to169 \({}^{\circ}\)C depending on the operating conditions. Figure 11a presents the thermal power exchanged in the preheater to reach the reactor inlet temperature considered. As expected, higher temperatures at the reactor entrance require greater energy exchanges. It is noticeable in terms of the amount of energy required, a significant reduction in the thermal power required when the glycerol mass concentration increases. Figure 11b shows the exhaust gas flowrate required for each operating condition. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameters Analyzed**} & \multicolumn{4}{c}{**Glycerol Mass Concentration in the Feed (wt.\%)**} \\ \cline{2-6}  & **10** & **15** & **20** & **25** & **30** \\ \hline Electricity from the ICE (kW) & 2289.3.5 & 2224.8 & 2160.2 & 2092.5 & 2027.9 \\ Electricity from the reactor hot effluent (kW) & 92.1 & 90.5 & 89.2 & 87.8 & 86.3 \\ Total Electrical Power (kW) & 2381.4 & 2315.3 & 2249.4 & 2180.3 & 2114.3 \\ Fuel thermal power (kW) & 5723.3 & 5561.9 & 5400.6 & 5231.3 & 5069.9 \\ Glycerol thermal power (kW) & 444.4 & 666.7 & 888.9 & 1111.1 & 1333.3 \\ Syngas thermal power (kW) & 177.2 & 264.7 & 351.7 & 438.9 & 526.2 \\ Electrical efficiency 1 (\%) & 41.61 & 41.62 & 41.65 & 41.67 & 41.70 \\ Electrical efficiency 2 (\%) & 38.61 & 37.17 & 35.76 & 34.37 & 33.02 \\ Electrical efficiency 3 (\%) & 41.48 & 41.42 & 41.35 & 41.29 & 41.23 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the results of case study A when the reactor inlet temperature is 530 \({}^{\circ}\)C.  
Figure 11: (**a**) Exchanged thermal power and (**b**) required exhaust gases flowrate from GT versus the temperatures at the reactor inlet in the range from 450 to 520 \({}^{\circ}\)C. Both figures are parametrized as functions of the glycerol mass concentration in the feed stream. In order to show the behavior of the hot and cold stream along the preheater, the same glycerol concentration used in the previous case study (20 wt.%) is considered. However, the reactor inlet temperature for this case is set at 520 \({}^{\circ}\)C and the minimum pinch point temperature at 10 \({}^{\circ}\)C. Under these conditions, the IQ curve for the preheater is shown in Figure 12a. For the hot fluid, the temperature is reduced from 530 \({}^{\circ}\)C to 165 \({}^{\circ}\)C, while the cold fluid temperature increases from 25 \({}^{\circ}\)C to 520 \({}^{\circ}\)C. Along the cold fluid curve, the change to the supercritical state that generates a singular curve around the critical temperature can be seen because of the sharp variation in properties.