# Residue Cost Formation of a High Bypass Turbofan Engine
## Appendix C Exergoeconomic Analysis  
The economic data of the engine were taken from Balli [1]: a total capital investment cost for the engine of \(TCI\) = 16,000,000.00 USD, engine overhaul and maintenance cost of \(OMC\) = 800,000.00 USD, engine operation hours in a year of \(\tau\) = 3000 h, interest rate of \(i\) = 10%, engine lifetime of \(N\) = 30 years, and engine salvage ratio of \(SV\) = 15%. Based on these data, the following economic parameters were estimated: the present value factor \(PVF=(1+i)^{-n}=0.05731\), present worth \(PW\) = \(TCI-SV\cdot PVF=\) 15,862,459.0 USD, capital recovery factor \(CRF=i(1+i)^{n}/[(1+i)^{n}-1]=0.1061\), annual capital cost \(ACC=PW\cdot CRF=\) 682,678.0 USD/year, hourly levelized total capital investment cost rate \(\dot{Z}^{TCI}=ACC/\tau\) = 560.893 USD, hourly levelized operating and maintenance cost rate of the system \(\dot{Z}^{OMC}=OMC/\tau\) = 266.667 USD/h, and total hourly levelized total cost rate of the engine \(\dot{Z}^{TOT}=\dot{Z}^{TCI}+\dot{Z}^{OMC}\) = 827.559 USD/h.  
In this study, the purchase cost of each productive component was determined from \(\dot{Z}_{i}=\omega_{i}^{Z}Z^{TOT}\) with \(\omega_{D}^{Z}\) = 5%, \(\omega_{F}^{Z}\) = 17%, \(\omega_{FN}^{Z}\) = 4%, \(\omega_{C}^{Z}\) = 22%, \(\omega_{CC}^{Z}\) = 14%, \(\omega_{HPT}^{Z}\) = 18%, \(\omega_{LPT}^{Z}\) = 12%, and \(\omega_{N}^{Z}\) = 8%. The price of the fuel Jet-A1 was considered as 27.04 USD/GJ [35], and the price for air was taken as zero.  
Table 20 presents the cost balance of each component of the GE90-115B turbofan engine.  
Columns \(f_{r}\) and \(f_{Z}\) of Table 21 correspond to the residue and component factors, respectively. They represent the contributions of the residue and component costs, respectively, to the production cost of each component [17]. These indicators are defined as \(f_{r,i}=\Pi_{p,i}/\Pi_{p,i}\) and \(f_{Z,i}=\Pi_{P,i}^{Z}/\Pi_{P,i}\), respectively. The exergoeconomic factor \(f_{P,i}=\dot{Z}_{i}/(\dot{Z}_{i}+c_{F,i}\dot{I}_{i})\) indicates the exergoeconomic costs of a component [17], which is the sum of the component cost (\(\dot{Z}_{i}\)) and the cost of the irreversibilities generated in this component (\(c_{F,i}\dot{I}_{i}\)). If the economic cost of the external resources of the \(i\)th component is zero, then \(f_{P,i}=1\), as is the case for the D. A low exergoeconomic factor for a component (\(f_{P,i}\to 0\)) suggests that the cost of the irreversibilities dominates and that the overall cost of the entire system may be reduced by improving the component efficiency (i.e., reducing the exergy destruction),even if the capital, operating, and maintenance costs for this component increase [41]. For the turbofan engine, the CC had a low exergoeconomic factor (\(f_{P,CC}=0.0147\) or \(1.47\%\)); therefore, the component performance could be improved, although this would be limited by the combustion process. An exergoeconomic factor close to unity indicates a low irreversibility cost compared with the component cost; therefore, it is not advisable to attempt to improve the efficiency of the process. In other words, this factor suggests decreasing the investment cost in that component at the expense of its exergetic efficiency [41]. The exergoeconomic indicators of \(f_{r}\), \(f_{Z}\), and \(f_{p}\) constitute a useful and simple tool for determining possible improvements in an energy system. However, they do not consider the effects induced by changes in the irreversibility of a component on other components.