## 4 Results and Discussions  
The cost rates associated with the exergy values of the streams of WHR systems are presented in Table 4. This table shows that the specific cost rate of the toluene stream at turbine inlet (1 ORC) is calculated to be 19.11 USD/GJ for the ENGINE/SORC and 16.26 USD/GJ for the ENGINE/RORC, and it is 18.16 USD/GJ for the ENGINE/DORC. The value of the cost rate of toluene organic fluid at ORC turbine, which is the device to produce power is determined to be 3.23\(\cdot\)10\({}^{-3}\) USD/s, 4.43\(\cdot\)10\({}^{-3}\) USD/s and 2.89\(\cdot\)10\({}^{-3}\) USD/s for ENGINE/SORC, ENGINE/RORC and ENGINE/DORC, respectively. Furthermore, Table 5 indicates that the ITC3, B1, and B2 fuel cost rate has an important contribution to the power production cost of the WHR configurations. The product cost of the B1 is found to be 1700.64 USD/GJ, which mean the highest cost difference presented in the process, due to the large pressure ratio required to operate the thermal oil and overcome the drop pressure in the hydraulic loop. The results show that a high level of capital is being invested compared to the rest of the equipment to obtain intermediate products in the system, such as the cost of thermal oil product in B1 in all the configurations being SORC (1700.64 USD/GJ), RORC (996.78 USD/GJ) and DORC (302.03 USD/GJ), and the cost of the organic fluid product in B2 being SORC (197.64 USD/GJ), RORC (161.52 USD/GJ) and DORC (201.58 USD/GJ). Related to the exergy rate of the products, it can be affirmed that this is low for these components, so the exergetic efficiency must be improved to achieve the same results at a lower cost. Table 6 shows the destruction and exergy loss costs for the WHR systems. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Component**} & \multicolumn{4}{c}{**Configurations of WHR Systems Based on ORC**} \\ \cline{2-7}  & \multicolumn{2}{c}{**SORC**} & \multicolumn{2}{c}{**RORC**} & \multicolumn{2}{c}{**DORC**} \\ \cline{2-7}  & \(\hat{\mathbf{C}}\) & \(\mathbf{c}\) & \(\hat{\mathbf{C}}\) & \(\mathbf{c}\) & \(\hat{\mathbf{C}}\) & \(\mathbf{c}\) \\ \hline
10 & 3.72 & 6.88 & 2.37 & 4.38 & 1.29 & 2.38 \\
11 & 0 & 0 & 0 & 0 & 0 & 0 \\
1 AT & 2.60 & 12.46 & 2.11 & 8 & 2.18 & 10.12 \\
1 ATg & 1.33 & 12.46 & 2.19 & 8 & 1.81 & 10.12 \\
1 ATf & 0.36 & 12.46 & 1 & 8 & 1.0 & 10.12 \\
1 ORC & 3.23 & 19.11 & 4.43 & 16.26 & 2.89 & 18.16 \\
1A & 0 & 0 & 0 & 0 & 0 & 0 \\
1g A & 0.59 & 11.01 & 0.64 & 9.43 & 0.97 & 28.20 \\  
ORC & - & - & 4.09 & 26.28 & 2.17 & 16.36 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cost rates \(\hat{\rm C}\) (10\({}^{-3}\) USD/s) and costs per unit of exergy \(c\) (USD/GJ). Table 6 shows that the condenser (ITC 3) has the highest value of \(\dot{C}_{D}\) among the other components in the SORC and RORC configuration, while in the RORC was the high-pressure evaporator heat exchanger (ITC 4). The \(f\) value of the ITC3 component is 18% (SORC) and 41% (RORC) as shown in Table 7, which indicates that the exergy destruction cost in this component dominates the purchase and operating cost. Therefore, this heat exchanger with a \(f\) value of 99% means in the DORC a great opportunity to optimize the size of equipment to reduce the purchase cost. After the ITC3, the ITC1 has the highest value of \(\dot{C}_{D}\) in the SORC configuration. The relatively low value of \(f\) in this equipment means that the cost rate of exergy destruction of the ITC1 is considerably higher than the purchase and operating cost rate for it, as a consequence of the large temperature difference between the thermal oil fluid and the exhaust gas from the engine. Therefore, another type of organic fluid should be studied in high-temperature ORC applications, and the selection of more expensive equipment will improve the exergoeconomic performance of these solutions.