## 3 Results and Discussions
### RORC Thermal Performance: Effect of the Condensing Temperature  
Now, a comparison of the impact of the change in condensing temperature, Tc, is shown, applied to three fluids, i.e., pentane, hexane, octane, where we can appreciate the influence that temperature variation has on the fluids, and for all cases, the fixed values of pressure ratio were maintained at 6 with an evaporator pinch point of 100, which has been used in the literature [62]. As shown in Figure 8a, at a condensation temperature of about 65 \({}^{\circ}\)C a net power of 77.19 kW was obtained with pentane, which resulted, for this condition of operation, in the highest net power among the three fluids. However, as the condensing temperature increased to 71 \({}^{\circ}\)C, the net power decreased considerably to 71.24 kW, whereas the net power using hexane increased to 75.31 kW at the temperature previously indicated. Therefore, with an increase in condensing temperature, a slight increase in net power was achieved using hexane, and a reduction in power using pentane. For octane, a net power of about 62 kW was maintained. Similarly, for an increase in condensing temperature, as shown from Figure 8b,d, when the condensing temperature is below 68 \({}^{\circ}\)C, pentane behaves correctly as a working fluid. However, when the condensing temperature is above 69 \({}^{\circ}\)C, the pressure ratio equals 6 and the pinch point of the evaporator reaches 100 \({}^{\circ}\)C, and hexane achieves overall thermal efficiency, ORC thermal efficiency, and overall exergetic efficiency superior to pentane. Thus, for these particular cases, it can be stated that there is no organic working fluid that can guarantee the best performance in all system operating ranges. In addition, a condensing temperature range from 65 to 68.6 \({}^{\circ}\)C implies the best overall exergetic efficiency from approximately 31.5% to 30.6% for pentane, followed by hexane with values from 30.5% to 30.7%, as shown in Figure 8d. Then, octane presented the lowest overall exergetic efficiency values ranging from 25.2% to 25.4%. Therefore, hexane and pentane differ, in that a good behavior of the variables of interest is observed for an increase in the condensing temperature, except for pentane, which shows decreasing behavior in the range between 65 \({}^{\circ}\)C and 71 \({}^{\circ}\)C. However, it was analyzed that at condensing temperatures below 68 \({}^{\circ}\)C, pentane shows more desirable results on the system, which is a consequence of the irreversibilities presented in the heat exchanger and turbine, as was concluded by [PERSON] et al. [38]. Figure 7: Performance of different fluids for a RORC system with varying pressure ratios. (**a**) Net power; (**b**) Increase in thermal efficiency; (**c**) RORC thermal efficiency; and (**d**) Global exergetic efficiency. Figure 9d shows the variability of the pinch point of the evaporator for pentane, hexane, and octane. As shown in Figure 9, at a pinch point of 92 \({}^{\circ}\)C, and keeping the conditions of condensing temperature at 65 \({}^{\circ}\)C and pressure ratio of 6 constant, the best performance was presented by pentane (82.45 kW), followed by hexane (79.96 kW), and octane (62.87 kW), respectively. Figure 9b,c shows that as the evaporator pinch point increases, the absolute increase in thermal efficiency and ORC thermal efficiency decreases [61], which is caused by increased heat transfer irreversibilities in the evaporator, besides a decrease in the difference in enthalpies of the fluid at the moment of expansion in the turbine, and consequently, a decrease in the generated power; results that have been confirmed by [PERSON] et al. [62]. In addition, Figure 9d shows that the evaporator pinch point with pentane at 92 \({}^{\circ}\)C, obtains an overall energetic efficiency of 33.69%, indicating that when the pinch point is increased to 98 \({}^{\circ}\)C, it continues to maintain an exergetic efficiency higher than hexane and octane.