## 6 Conclusions  
DORC is used for ICE waste heat recovery. The HTL evaporation temperature, condensation temperature and superheat degree are optimized by genetic algorithm, and the net power output is the objective function. The effects of \(T_{\rm g1}\) on net power output, thermal efficiency, exergy efficiency, HTL evaporation temperature, HTL condensation temperature, HTL superheat degree, exhaust gas temperature at the exit of the HTL evaporator, heat utilization ratio, and exergy destruction rate are analyzed.  
Figure 16: Effects of \(T_{\rm g1}\) on exergy destruction rate for the benzene system.  
Figure 17: Effects of \(T_{\rm g1}\) on exergy destruction rate for the toluene system.  
The main conclusions are obtained as follows:  
1. The net power output of the DORC is primarily influenced by the HTL working fluid, and the relative deviation between the maximal and minimal net power outputs affected by the LTL working fluid is less than 3%. When \(T_{\text{g1}}\) is 523.15-598.15 K, cyclopentane is the optimal HTL working fluid for maximizing the net power output; when \(T_{\text{g1}}\) is 603.15-618.15 K, cyclohexane is the optimal HTL working fluid; when \(T_{\text{g1}}\) increases to 623.15 K, benzene is the optimal HTL working fluid. R1234 ze(E) is the optimal working fluid of LTL.  
2. The optimal HTL evaporator temperature increases with \(T_{\text{g1}}\) until reaching the upper limit. The optimal HTL condensation temperature initially increases and then remains unchanged for the cyclopentane system; in addition, it is maintained at a lower limit of the HTL condensation temperature for the cyclohexane, benzene, and toluene systems. Saturated cycle is suitable for these systems. Superheat cycle can improve the net power output for the cyclopentane system with \(T_{\text{g1}}\) of 568.15-623.15 K.  
3. The optimal exhaust gas temperature at the exit of the HTL evaporator is not constantly at the lower limit, but is at the lower limit for the cyclopentane system at 568.15-623.15 K; the exhaust gas temperature at the exit of the HTL evaporator is higher than the lower limit for the cyclohexane, benzene and toluene systems. The increase in exhaust gas temperature can improve the heat utilization ratio.  
4. Variations in the exergy destruction rates with \(T_{\text{g1}}\) are distinct for the different HTL working fluid systems. \(I_{\text{Hout}}\) and \(I_{\text{LC}}\) are the top two in most cases. When cyclopentane is used and exhaust gas temperature is 623.15 K, and the minimal \(I_{\text{Hout}}\) is 7.8%. \(I_{\text{P}}\) is the minimal exergy destruction rate.  
**Author Contributions:** Conceptualization, Z.G. and Y.D.; methodology, Z.G. and J.L.; software, Z.G.; validation, Z.G. and J.L.; formal analysis, Z.G. and J.L.; investigation, Z.G.; resources, Y.D. and Z.Y.; data curation, Z.G. and J.L.; writing--original draft preparation, Z.G.; writing--review and editing, Z.G., J.L., Y.D. and Z.X.; visualization, Z.G.; supervision, Y.D.; project administration, Y.D. and Z.Y.; funding acquisition, Y.D., Z.Y. and Z.X.  
**Funding:** This research was funded by National Natural Science Foundation of China, grant number 51736005, 51621062 and 11461078.  
**Acknowledgments:** This work was supported by the National Natural Science Foundation of China (Grant Nos. 51736005, 51621062 and 11461078).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Nomenclature**  
\(c_{p}\) specific heat capacity at constant pressure (kJ/(kg\(\cdot\)K))  
\(E\) exergy (kW)  
\(g\) gravitational acceleration (m/s\({}^{2}\))  
\(H\) pressure head (m)  
\(I\) exergy destruction rate (%)  
\(h\) specific enthalpy (kJ/kg)  
\(m\) mass flow rate (kg/s)  
\(p\) power (kW)  
\(s\) specific entropy (kJ/(kg\(\cdot\)K))  
\(T\) temperature (K)  
\(\Delta T\) temperature difference (K)  
**Greek symbols**  
\(\eta\) efficiency