## 1 Introduction
\begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{**Specification**} \\ \hline Engine & 18V/32/40 \\ A (mm) & 8300 \\ B (mm) & 4450 \\ C (mm) & 12,750 \\ H (mm) & 5240 \\ W (mm) & 3500 \\ Weight (t) & 139 \\ \hline \multicolumn{2}{c}{**Exhaust gas data**} \\ \hline Temperature at turbine outlet & 306 \({}^{\circ}\)C \\ Mass flowrate & 15.1 kg/h \\ Volume flowrate & 92,700 m\({}^{3}\)/h \\ Pressure (abs.) & 1.03 bar \\ Permissible pressure drop after turbine & \textless{}0.03 bar \\ \hline \multicolumn{2}{c}{**Savenged air data**} \\ \hline Temperature at the compressor inlet & 25 \({}^{\circ}\)C \\ Temperature at the air cooler outlet & 42 \({}^{\circ}\)C \\ Mass flowrate & 14.7 kg/h \\ Volume flowrate & 48,000 m\({}^{3}\)/h \\ Pressure (abs.) & 3.2 bar \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Specifications of the Doosan-MDT: 18V32/40 for AAC diesel generator. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**NPP site** & **Unit** & **No. of DG** & **Power (kW)** & **Vendor (Engine/Generator)** \\ \hline \multirow{2}{*}{[PERSON]} & EDG 3/4 & 4 & 8000 & Doosan-MDT: 16 PC2.6B, Alstom \\  & AAC DG 3, 4 & 1 & 7200 & Doosan-MDT: 16 PC2.6B, Alstom \\ \hline \multirow{2}{*}{[PERSON]} & EDG 1/2 & 4 & 7200 & Doosan-SEMT: 16 PC2-5V400, Alstom \\  & AAC DG 1, 2 & 1 & 7200 & Doosan-MDT: 18V32/40, Hyundai \\ \hline \end{tabular}
\end{table} 
Table 3: Status of EDG & AAC DG of APR 1400 [3]. Figure 2: Schematic diagram of the Doosan-MDT: 18V32/40 for AAC diesel generator. options [4]. According to the review of the previous studies on the S-CO\({}_{2}\) cycles, it was verified that the S-CO\({}_{2}\) cycle has a strong potential to outperform the conventional steam cycle or organic Rankine cycle, particularly in waste heat recovery applications [5]. The major reasons are as follows: high efficiency at a moderate turbine inlet temperature (450-750 \({}^{\circ}\)C) which significantly decreases maintenance and material problems, compact turbomachinery and heat exchangers which save the initial investment, and a simple layout which significantly reduces the overall footprint of the power plant [6]. The main feature of the S-CO\({}_{2}\) Brayton cycle is lower compression work than the other gas Brayton cycles because of S-CO\({}_{2}\) fluid's its high density and low compressibility near the critical point. Therefore, this characteristic makes the S-CO\({}_{2}\) cycle having fewer material issues than water and consequently leads to a higher turbine inlet temperature [7]. Moreover, the cooling and chemistry control system of S-CO\({}_{2}\) cycle are relatively simple than the steam Rankine cycle, the operation cost and the whole footprint of the power plant can be greatly decreased [8]. Because of these advantages, the S-CO\({}_{2}\) cycle is recently considered as the potential power cycle of conventional and renewable energy systems such as fossil fuel power plants, concentrated solar power systems, geothermal power plants, fuel cells, next generation nuclear power plants, and ship propulsion application. In this paper, a comparison of six S-CO\({}_{2}\) power cycle layouts recovering waste heat of s 7.2 MW AAC DG is presented in order to evaluate which S-CO\({}_{2}\) cycle layout is the most qualified for a diesel engine application. Moreover, a sensitivity study of the cycles with design parameters was carried out, and thermodynamic performance results of the cycles were evaluated. After that, key components of the waste heat recovery system will be designed, and off-design analysis of the designed S-CO\({}_{2}\) bottoming cycle will be presented.