Energy, Exergy and Economic (3E) Analysis and Optimization of a Combined Heat and Power (CHP) Plant

In this paper, a combined gas-steam power plant using exhaust heat to produce hot water is estimated in terms of energy, exergy and economics (3E). The examined parameters included the pressure ratio of the air compressor
$(\mathbf{r}_{\mathbf{p}})$
, the gas turbine inlet temperature, the steam turbine inlet pressure and the condenser pressure to evaluate thermal performance, exergy performance, and total annual cost (TAC). The mathematical model was established and solved in the environment of Engineering Equation Solver (EES) with comparison of results from the Aspen HYSYS simulator. The calculation results show that the exergy efficiency is maximum at
$\mathbf{r}_{\mathrm{p}}=\mathbf{11}$
. TAC is strongly influenced by gas cycle operating parameters. The minimum TAC can obtain at the steam turbine inlet pressure of 5,300 kPa. Overall optimization reveals maximum efficiencies and minimum cost at pressure ratio of 8.65, gas turbine inlet temperature of 1460 K, the smallest condenser pressure, and the highest steam turbine inlet pressure.