Sharif Digital Repository

The supplementary firing is one of the techniques which are used to increase the output power of the combined cycle power plants (CCPP). The low construction cost per generated power encourages designers to consider it in the new CCPP. In this paper the thermal and exergy analyses of HRSG for various operating conditions in variation of loads and variation of ambient temperature carried out. They are based on the performance test data at different operating conditions. The objective of these analyses is to present the effects of supplementary firing on gross power output, combined cycle efficiency and the exergy loss in Heat Recovery Steam Generator (HRSG) devices at different ambient... 

Piping systems commonly experience the transient-state situation as the result of changes to flow conditions during pump failures, valve closures or turbine load rejection. This paper addresses transients as a consequence of the load rejection of a Francis hydropower plant (Karun 4, Ahwaz, Iran). To control the turbine system and related equipment during load rejection, the valve closing law of wicket gates is of paramount importance. The pressure rise at the end of the pressure shaft, the pressure drop in the draft tube and the speed rise while the electromagnetic braking torque disappears are solely dependent on the closing curve. Thus, an optimum closing law can eliminate the probable...