## 3 Results and Discussions
### Energy and Exergy Analysis of the RORC Configuration  
The base condition parameters considered for this investigation in the RORC system are shown in Table 5. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameters** & **Proposed Model** & **[PERSON] [50]** & **Absolute Deviation (\%)** & **[PERSON] et al. [38]** & **Absolute Deviation (\%)** \\ \hline \(\eta_{th}\) (\%) & 16.26 & 16.15 & 0.68 & 16.37 & 0.67 \\ \(\eta_{ex}\) (\%) & 48.67 & 48.54 & 0.27 & 48.8 & 0.27 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Validation of the proposed model for the RORC system. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters** & **Values** & **Unit** \\ \hline Cooling temperature & 50 & \({}^{\circ}\)C \\ Pinch point evaporator & 90 & \({}^{\circ}\)C \\ Pinch point condenser & 15 & \({}^{\circ}\)C \\ Exhaust gas temperature & 435.07 & \({}^{\circ}\)C \\ Outlet gas temperature & 270 & \({}^{\circ}\)C \\ Pressure ratio pump 1 & 2.5 & \\ Ambient temperature & 30 & \({}^{\circ}\)C \\ Ambient pressure & 101.3 & kPa \\ Hours of operation per year & 7446 & h \\ Turbine isoentropic efficiency & 80 & \% \\ Pumps isoentropic efficiency & 75 & \% \\ Regenerator effectiveness & 85 & \% \\ Pressure ratio pump 2 & 4 & \\ Fuel mass flow & 9986.04 & kg/h \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Base condition parameters for a RORC system. Taking into account the parameters established in Table 5 the thermodynamic properties were obtained for each point of the RORC System duct shown in Table 6.  
From the simulation results obtained and the thermodynamic properties, some energy and exergy parameters of the WHR system from the engine were calculated, as shown in Table 7. These results show that the WHR system in the base condition result in an increase in thermal efficiency of 1.58% for the natural gas engine, and the RORC has a thermal efficiency of 13.95% and a volumetric energy capacity of 16.28 kJ/m\({}^{3}\), which considers the change enthalpy of the system in relation to the density at the exit of the expander. The exergy balance was calculated for all the components, as shown in Table 8 which shows the results of traditional exergetic analysis based on the inputs and outputs of the components. To perform the heat exchange from the residual steam of the internal combustion engine to the ORC, Therminol 75 is used as a heat exchange fluid, which on its passage through the three-stage heat exchanger transfers heat to the working fluid which changes from the liquid phase to the vapor phase. Previously, the temperature of the working fluid had been increased by means of a regenerator to improve the process in the exchanger. A diagram of the process is shown in Figure 4, where the entire \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**State** & **T (K)** & **P (kPa)** & **H (kJ/kg)** & **(S-S\({}_{0}\)) (kJ/kg K)** & **E (kW)** \\ \hline
4 ORC & 338.15 & 247.17 & 70.76 & 0.26 & 5.37 \\
5 ORC & 338.64 & 988.69 & 72.47 & 0.29 & 6.83 \\
6 ORCr & 397.49 & 988.69 & 232.17 & 0.73 & 38.03 \\
6 ORC & 397.49 & 988.69 & 448.30 & 1.24 & 94.85 \\
6 GRC & 397.49 & 988.69 & 497.21 & 1.37 & 107.71 \\
1 ORC & 559.44 & 988.69 & 913.44 & 2.27 & 275.16 \\
2 ORC & 531.13 & 247.17 & 846.54 & 2.31 & 190.42 \\
3 ORCr & 371.92 & 247.17 & 470.70 & 1.47 & 54.38 \\
3g ORC & 338.15 & 247.17 & 403.41 & 1.28 & 43.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Thermodynamic properties of the RORC system. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **RORC** & **Units** \\ \hline Thermal efficiency engine-ORC & 40.17 & \% \\ Increased thermal efficiency & 1.58 & \% \\ Thermal efficiency ORC & 13.95 & \% \\ Global energy conversion & 5.69 & \% \\ Global exergetic efficiency & 29.35 & \% \\ BSFC engine-ORC & 177.5 & g/kWh \\ Volumetric energy capacity & 16.28 & kJ/m\({}^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Performance parameters obtained for the waste heat recovery (WHR) system based on RORC.