## 3 Results and Discussion  
The goal of this project is to use coupled cycles to recover the waste heat in an FG from an industrial furnace. In SRC, ORC, and KC, respectively, FG was used to produce electrical energy. The FG temperature employed in the SRC was investigated parametrically in order to maximize the waste heat of FG in the cycles. The optimal point was determined to be the one that resulted in the lowest cost of producing electricity. Analysis was done on the net power production for each cycle (\(\dot{\mathrm{W}}_{\mathrm{net}}\)), thermal efficiency (\(\eta_{\mathrm{th}}\)), and the cost of producing electricity (\(\dot{\mathrm{Z}}_{\mathrm{electricity}}\)). Additionally, energy balances were constructed, heat recovery potentials were disclosed, and relevant computations were performed utilizing the measurement data of the FG from the AF. The findings of parametric studies and the results computed using constant data for each coupled system are presented below, section by section. Figure 2 represents the T\(-\)s diagram of SRC considering the optimum mass flowrate. As seen in the T\(-\)s diagram of SRC, the working fluid enters the pump as a saturated liquid at 0.6 bar pressure and 369.5 K temperature and is compressed at 150 bar pressure in the pump. It is assumed that the pump and turbine are isentropic. Using the heat taken from the FG, the temperature is increased to 873 K and expanded to 30 bar and 660 K in the high-pressure turbine. Afterwards, the temperature is increased to 873 K at constant  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Cycle** & **Component** & **Correlation** & **Explanation** & **Ref. ** \\ \hline \multirow{5}{*}{\(\mathrm{Cond}=\mathrm{Q}/\mathrm{U}(\mathrm{A}\mathrm{T}\mathrm{m})_{\mathrm{R}}\)} & steam turbine & PEC\({}_{\mathrm{ST,SRC}}=405\dot{\mathrm{W}}_{\mathrm{T}}\) & - & [27] \\  & condenser & PEC\({}_{\mathrm{cond,SRC}}=588\mathrm{A}_{\mathrm{Cond}}\)\({}^{0.8}_{\mathrm{B}}\) & \multirow{2}{*}{\(\mathrm{A}_{\mathrm{Cond}}=\mathrm{Q}/\mathrm{U}(\mathrm{A}\mathrm{T}\mathrm{m})_{ \mathrm{R}}\)} & [28] \\  & pump & PEC\({}_{\mathrm{wp,SRC}}=1120\dot{\mathrm{W}}_{\mathrm{P}}\) & - & [23] \\  & evaporator & PEC\({}_{\mathrm{eva,SRC}}=6570\Big{(}\frac{\mathrm{Q}}{\mathrm{A}\mathrm{T}\mathrm{m}} \Big{)}^{0.8}+21276\dot{\mathrm{m}}_{\mathrm{src}}+1184.4\dot{\mathrm{m}}_{ \mathrm{fg}}\) & \multirow{2}{*}{Q: heat transfer from fine gas} & \multirow{2}{*}{\(\mathrm{\Delta T\mathrm{m}}\): Logarithmic mean} & \\  & & temperature difference & & \\ \hline \multirow{5}{*}{\(\mathrm{Cond}=\mathrm{Cond}=\mathrm{Q}/\mathrm{U}(\mathrm{A}\mathrm{T}\mathrm{m})_{ \mathrm{R}}\)} & turbine & PEC\({}_{\mathrm{turbine}}\)\({}_{\mathrm{CO}_{2}}=866.64\dot{\mathrm{W}}_{\mathrm{T}}\) & - & [29] \\  & condenser & PEC\({}_{\mathrm{cond,CO}_{2}}=2143\dot{\mathrm{A}}_{\mathrm{Cond}}\)\({}^{0.51  
pressure by applying reheating. In the low-pressure turbine, the working fluid expands to the condenser pressure of 0.6 bar and 369.5 K. Finally, saturated liquid is obtained in the condenser and heat rejected into the CO\({}_{2}\) cycle. In the T\(-\)s diagram of CO\({}_{2}\), the working fluid enters the condenser as a saturated liquid at 233.028 K at a pressure of 10 bar as indicated in Figure 3. The CO\({}_{2}\) pressure rises to 90 bar, which is the condenser pressure in the pump. It is assumed that the pump and turbine are isentropic. The fluid temperature is increased to 359.5 K before the turbine inlet by using the heat released from the condenser of the SRC. The cycle is supercritical because the phase change takes place above the saturation curve. In the CO\({}_{2}\) turbine, the fluid expands to 233,028 K and 10 bar. The cycle is completed by heat rejection in the condenser to the oxygen line at constant pressure. Figure 3: T\(-\)s diagram of CO\({}_{2}\) cycle. Figure 2: T\(-\)s diagram of SRC. As it is clearly observed in Figure 4, R245 fa enters the pump as a saturated liquid at a temperature of 299.184 K and a pressure of 1.5 bar.