exergetic optimization of designing parameters for heat recovery steam generators through direct search method

in this paper, first a sensitivity analysis of parameters affecting the performance of the steam generator is performed. this process includes the pinch temperature difference and the gas velocity (width of the hrsg) as the operating parameter and geometrical parameters (fin’s thickness, fin’s height, number of fins in each inch, tube transverse pitch) for each pressure parts is carried out, and then these parameters have been optimized. geometry details of the fins were considered separately for each pressure part of the steam generator (economizer, evaporator and superheater). the considered objective function is the rate of irreversibility in the steam generator which constitutes exergy destruction rate and exergy loss rate. after the optimization of total irreversibility rate, thermal and exergetic efficiencies and components of irreversibility, including exergy destruction for each part and exergy loss are calculated and compared with the situation prior to optimization.