## 4 Results and Discussions
### Sensitivity Analysis
#### 4.1.2 Relative Cost Difference and Exergoeconomic Factor Analysis  
Figure 5 shows the effect of the evaporating pressure on the relative costs difference by components for each WHR system. Figure 5a shows the decrease in the relative cost of B2 and ITC1 by increasing the evaporating pressure from 0 MPa to 1 MPa. However, these two components have lower relative costs to higher pressures, which is because the cost values of exergy destruction, investment costs, operation, and maintenance are significantly higher than the product cost of exergy. A similar case happens for ITC 3 and the recuperator in the RORC, as shown in Figure 5b. In the DORC case, as shown in Figure 5c, ITC2, B1, B2, and B3 show the highest relative cost values associated with the exergy destruction. However, these components present a relative cost decrease of 139%, 17%, 142%, and 95% respectively, which confirms that this parameter allows a better energetic performance only of these components since they do not significantly affect the overall thermoeconomic performance of the configuration. Likewise, the results show that the specific cost of exergy in the ITC 1 and condenser in the three WHR systems maintains a constant value in the vaporization pressure range studied, which can be explicated because of the exergy loss do not take excessively large values. Figure 4: Effect of evaporating pressure and turbine efficiency on the cost rate of exergy destruction by component, (**a–d**) SORC, (**b–e**) RORC, and (**c–f**) DORC. The high values of relative cost difference and exergoeconomic factor for B1 (rk = 8.5, fk = 80%), B2 (rk = 8, fk = 85%) and T1 (rk = 1, fk = 85%) at a pressure of 0.2 MPa, in the SORC as shown in Figure 5a,d, are due to the high purchase, operation and maintenance costs that make the proposed WHR system more expensive. Therefore, in the case of pumps, the possibility of purchasing ones that cause less increase in the exergy unit by sacrificing the value of the exergetic efficiency should be evaluated. For the RORC configuration, the ITC2, ITC3, and RC heat exchanger equipment have lower exergy destruction cost-plus purchase values than T1, so operation at a different evaporating pressure will not significantly influence the overall performance of the system. The high costs in the condenser and its increase in evaporating pressure are associated with a high value of exergy destruction, in addition to the inefficiencies of the heat exchange process at the end of the process. An important feature is that exergetic losses are not attributed exclusively to one component of the system; it is in this device where there are the highest exergetic losses and the highest values of exergy loss costs. In addition, being a device located in the final part of the process, the unitary exergetic cost considered for its valorization is very high. Regarding the exergoeconomic factor, the values of the condenser and the evaporator are 20% and 45% at a pressure of 0.2 MPa respectively as shown in Figure 5e, which are the lowest in the proposed configuration, so that the exergetic unit does not become excessively expensive when passing through these devices in relation to the others in the process. Figure 5: Effect of evaporation pressure on relative cost difference and exergoeconomic factor per component, (**a–d**) SORC, (**b–e**) RORC, and (**c–f**) DORC. Figure 5f shows the influence of the evaporation pressure for each of the components of the DORC configuration, where the exergoeconomic factor takes values close to 100% for all the components, which shows that the purchase costs of the equipment are more relevant than the cost rate for the exergy destruction and exergy loss, and the costs associated with the maintenance of the equipment. Therefore, the savings potential of these WHR systems depends on the operating conditions of each component and the operation of the gas engine.