Optimum design and performance improvement of the Heat Recovery Steam Generator (HRSG) have noticeable effects on the thermal efficiency of the combined cycle power plants. Therefore, HRSG must be designed in such way that maximizes the heat recovery and improves the overall performance of the plant.
In this paper, a method for design and optimization of a triple pressure HRSG is proposed. It is shown how to simultaneously optimize the operating and geometric design parameters of the HRSG by using the constructal theory. Considering the minimum total entropy generation as the objective function, the optimum parameters in the HRSG unit are derived by using the genetic algorithm method under the fixed total volume condition. Optimized total volume is derived by converting the exergy destruction to cost of entropy generation in order to compare with the capital cost and the results show that there is a trade-off between them. Also, aspect ratios of the units, the heat transfer area for each component of the HRSG and thermodynamic properties are significant features of the flow configuration inducted by the Constructal design. Furthermore, the effects of changing in the temperature and flow rate of hot gas on the optimal values of the total volume, power and steam production are determined.