## 4 Conclusions  
In this paper, an improved analysis method for the ORC system is proposed. To study the influence of turbine efficiency selection on the ORC system, a radial-inflow turbine efficiency prediction model is coupled with the ORC system. Multi-objective optimization was conducted for the ORC\({}_{\text{CTE}}\) system and the ORC\({}_{\text{DITE}}\) system, and the optimization results were compared. In addition, a sensitivity analysis was conducted with respect to heat source temperature and ambient temperature. The following conclusions can be obtained:  
1. Turbine efficiency is not constant, it decreases with the increasing evaporation temperature, and increases with the increasing condensation temperature. For radial-inflow turbine with organic working fluid benzene, the largest difference between the predicted turbine efficiency and the constant turbine efficiency is 0.157 for the given operating conditions.
2. The distribution of the Pareto frontier for the ORC\({}_{\text{CTE}}\) system and the ORC\({}_{\text{DITE}}\) system are different. Compared with the ORC\({}_{\text{CTE}}\) system, the ORC\({}_{\text{DITE}}\) system has a lower optimal evaporation temperature but a slightly higher optimal condensation temperature.
3. As the heat source temperature increases, the deviation between the predicted turbine efficiency and constant turbine efficiency increases, and the error in the theoretical analysis results caused by assuming a constant turbine efficiency in ORC system increases. Meanwhile, with the increasing ambient temperature, the deviation between the predicted turbine efficiency and the constant turbine efficiency decreases, and the error in the theoretical analysis results caused by assuming a constant turbine efficiency decrease.  
**Author Contributions:** All authors contributed to this work. [PERSON] is the main author of this work. [PERSON] guided the analysis and the writing of the paper. [PERSON] and [PERSON] assisted with the modeling. [PERSON] and [PERSON] provided suggestions with respect to article modification.  
Figure 17: Turbine efficiency at different ambient temperature.  
Figure 18: Net power output at different ambient temperature.  
**Funding:** This research was funded by the National Natural Science Foundation of China (Grant No. 51306059) and Fundamental Research Funds for the Central Universities (Grant No. 2017 XS120).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Nomenclature**  
\(c\): absolute velocity, m s\({}^{-1}\)  
\(C\): capital cost, $  
\(D\): diameter, m  
\(\overline{D}_{2}\): ratio of wheel diameter  
\(f\): coefficient for friction loss  
\(h\): specific enthalpy, kJ kg\({}^{-1}\)  
\(l\): blade height, m  
\(m\): mass flow rate, kg s\({}^{-1}\)  
\(P\): pressure, MPa  
\(Q\): heat transfer rate, kW  
\(T\): Temperature, K  
\(U\): peripheral velocity, m s\({}^{-1}\)  
\(v\): specific volume, m\({}^{3}\) kg\({}^{-1}\)  
\(w\): relative velocity, m s\({}^{-1}\)  
\(W\): power, kW  
**Greek Letters**  
\(\eta\): efficiency  
\(\overline{u}_{1}\): velocity ratio  
\(\xi\): loss coefficient  
\(\varphi\): stator blade velocity coefficient  
\(\psi\): rotor blade velocity coefficient  
\(\alpha\): absolute flow angle  
\(\beta\): relative flow angle  
\(\Omega\): degree of reaction  
\(\Delta h\): entropy drop, kJ kg\({}^{-1}\)  
\(\Delta Tp\): pinch point temperature difference, K  
\(\delta\): tip clearance, m  
**Subscripts**  
\begin{tabular}{l l}
0, 1, 2, 2s, 4, 5s, 5 & state points \\ BM & bare module \\ con & condenser \\ critical & critical \\ eva & evaporator \\ f & working fluid \\ g1 & flue gas inlet \\ max & maximum \\ min & minimum \\ net & net \\ opt & optimal \\ pump & pump \\ s & isentropic \\ tur & turbine \\ the & thermal \\ u & peripheral \\ \end{tabular}