## 4 Results and Discussion
### Combined ORC-Dual Evaporator VCR Cycle Results
The reason of this situation can be thought to be not changing of compressor power and thus turbine power. \(\dot{\text{n}}_{\text{ORC}}\) does not change if there is no change in turbine power. In addition, \(\dot{\text{n}}_{\text{VCR}}\) almost remains the same because of assumption of constant cooling loads. Eventually, \(\dot{\text{n}}_{\text{total}}\) does not change. Figure 15 shows influence of change of ambient temperature on COP\({}_{\text{sys}}\) for dual evaporator system. We accepted to be 5 \({}^{\circ}\)C temperature difference between ambient and condensers while investigating effect of ambient temperature. Temperature difference of 5 \({}^{\circ}\)C was only used while drawing this graph. Previous Figures 13 and 14 assume ambient temperature to be constant. According to graph, increase in ambient temperature causes decrease in COP\({}_{\text{sys}}\). Because of the fact that compressor power will go up with increase in ambient temperature, COP\({}_{\text{sys}}\) will decrease. Graphs indicating effect of boiler and condenser temperatures as well as turbine and compressor isentropic efficiencies on system performance for the combined ORC-dual evaporator VCR cycle were not included in this article since their tendencies are exactly the same as combined ORC-single evaporator VCR cycle. It can be observed from Figures 13 and 14 that R600a gives best COP\({}_{\text{sys}}\) and \(\eta_{\text{lex,sys}}\), therefore can be selected as the most efficient working fluid among four fluids. Using R600a, T-s and P-h diagrams of the system are depicted in Figure 16a,b, respectively. Figure 15: Influence of T\({}_{0}\) on COP\({}_{\text{sys}}\) in combined ORC-dual evaporator VCR cycle. destruction happens in the mixing chamber with almost negligible amount. Also, the component that has the highest exergy destruction in refrigeration cycle is the compressor. The reason why the third valve has exergy destruction rate of equal to sum of the first and second valves is that vapor is expanded in valve three. Expansion of vapor will produce much more entropy than expansion of liquid as in first and second valves. Figure 18a,b depict the second law efficiency and degree of thermodynamic perfection for each component in the system, respectively. The component having the biggest second law efficiency in combined system is mixing chamber as represented in Figure 18a. This is followed by first evaporator and pump. The reason for zero second law efficiency in both of condensers is equivalent heat sink and ambient temperatures. Also, all of the expansion valves have zero second law efficiency since there are no exergy transfer in valves. Figure 18b indicates that pump gives the highest degree of thermodynamic perfection. As in combined system with single evaporator, the difference between second law efficiency and degree of thermodynamic perfection of some components exists for this  
Figure 17: Exergy destruction rate (**a**) and exergy destruction ratio (**b**) of components in combined ORC-dual evaporator VCR cycle. system too. This situation explains that theoretical ultimate point is not reached in terms of exergy. More exergy can be achieved as much as difference between second law efficiency and degree of thermodynamic perfection.