## 4 Conclusions  
In this paper, a combined cycle power plant was analyzed to observe the performance of a combined gas and steam power plant under varied component parameters. The proposed system was modelled using the Thermolib extension library in MATLAB. The results obtained from the system gave the net power from the Brayton cycle, Rankine cycle and overall system as 7.41 MW, 29.91 MW, and 24.75 MW respectively. The efficiencies were found to be 33%, 36%, and 62% respectively. The overall exergy efficiency of the multigeneration system was calculated as 78%. The ammonia heat pump had an output of 1.39 MW with a COP of 9.1.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Component** & **Exergy Destruction Rate (kW)** & **Share of Total (\%)** \\ \hline Compressor 1 & 137.3 & 2.8 \\ Combustion chamber & 2774.5 & 56.6 \\ Turbine 1 & 465.7 & 9.5 \\ HRSG & 500.0 & 10.2 \\ Turbine 2 & 176.5 & 3.6 \\ Condenser 1 & 529.4 & 10.8 \\ Pump & 14.7 & 0.3 \\ Evaporator & 88.2 & 1.8 \\ Compressor 2 & 117.6 & 2.4 \\ Condenser 2 & 93.1 & 1.9 \\ Valve & 4.9 & 0.1 \\ Total & 4902 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Exergy destruction for each component in the system.  
Figure 9: Impact of varying the combustion inlet energy rate on the exergy stability factor and exergetic sustainability index of the overall system.  
The outcome of the study showed that using different pressure ratios ultimately affected the gas cycle and the overall system performance, as it increased the gas turbine compressor work, gas turbine output power, the net power output, and the overall efficiency of the system. Increasing the pressure ratio of the Brayton cycle from 3 to 9 increased the Brayton cycle output power from 7.2 MW to 12.3 MW, while the net power output increased from 13.9 MW to 18.8 MW. Varying the pressure ratio also increased the efficiency of the Brayton cycle from 24% to 42%, while the combined efficiency of both the Brayton cycle and the Rankine cycle increased from 49% to 66%. Increasing the steam turbine inlet pressure from 4 MPa to 16 MPa increased the Rankine cycle power output from 6.5 MW to 7.7 MW, while the overall efficiency of the system increased from 62% to 66%. The heat flow rate into the combustion chamber also varied from 25 MW to 35 MW, and this caused the net power output of the system to increase from 15.5 MW to 19 MW. The exergoenvironment analysis of the system showed the appropriateness, usefulness, and stability of the multigeneration system in the environment.  
The effect of varying the combustion inlet energy rate on the exergoenvironment impact of the overall system was also analyzed. The results showed favorable exergoenvironmental effects, indicating a reduction in the system's overall irreversibility and environmental impact, made possible by the improved combustion efficiency in the combustion chamber.  
Formal analysis, H.A.; Investigation, M.A. ([PERSON]); Methodology, M.A. ([PERSON]) and D.A.; Supervision, J.H.Z.; Writing--original draft, H.A. ([PERSON]) and D.A.; Writing--review & editing, A.T.O. All authors have read and agreed to the published version of the manuscript.  
This work is funded by Universiti Brunei Darussalam, under the grant # UBD/RSCH/1.3/FICBF(b)/2022/017.  
Not applicable.