The current study deals with the thermodynamic modeling, and multi-objective optimization of a pressure reduction
station integrated with an organic Rankine flash cycle (ORFC) and a thermoelectric generator (TEG)
waste heat recovery system (WHRS). Using the real operating data of a city gate station (CGS), a thermodynamic
simulation was developed using EES (Engineering Equation Solver). The exergy analysis as a rigorous method
was applied to find the exergy destructive components of the integrated system. Computations indicate that the
exergy efficiencies of the indirect water bath heater (IWBH), ORFC condenser and TEG modules are 1.41%,
30.45%, and 16.34%, respectively, which are the lowest asset values among all components.
Five main decision variables were defined as objective functions by the parametric study of the integrated
system. Results of multi-objective optimization offer a set of non-dominant optimization solutions. A criterion for
optimum state selection is carried out with the definition of an ideal point on the Pareto diagram, where point B
is picked as a favorable system state.
The scattered distribution of decision variables at points (offered by the Pareto solution) represents that ṁNG
and − TNG 2 tend to be at the lower bound of their allowable range in all optimum states. Moreover, a comparison
between the non-optimal and optimal integrated system reveals that the total exergy destruction rate through
the system decreases 337.62 kW, and the thermal efficiency increases 8.57% in the optimal state.