Investigating the effect of duct burner fuel mass flow rate on exergy destruction of a real combined cycle power plant components based on advanced exergy analysis

• The effect of ṁDB is investigated on exergy destruction parts of each component.
• Increment of ṁDB elevates the avoidable exergy destruction of HP.SUP, LP.EVAP and LP.ST.
• Increase of ṁDB, reduces the unavoidable exergy destruction only in HP.ST and DEAR.
• Increase of ṁDB, has the maximum decrement of the total exergy destruction on ECO1.

In this research, an advanced exergy analysis of a real combined cycle power plant (CCPP) with supplementary firing is investigated. The endogenous/exogenous irreversibilities of each component and their combination with avoidable/unavoidable irreversibilities are identified. Furthermore, parametric study of the total exergy destruction, thermal and exergetic efficiencies and different parts of exergy destruction of each component are examined as a function of duct burner fuel mass flow rate (ṁDB). It is revealed that the avoidable exergy destruction of CCPP decreases within 23.9% while its unavoidable part increases by about 50% as ṁDB increases. In addition, the endogenous avoidable exergy destruction of CCPP gets 3 times while its exogenous part of avoidable is reduced within 86% by increasing ṁDB. It is found that the growth of ṁDB elevates the potential improvement of high pressure superheater (HP.SUP), low pressure evaporator (LP.EVAP) and low pressure steam turbine (LP.ST), and decreases the avoidable exergy destruction of the high pressure evaporator (HP.EVAP) and duct burner (DB). Moreover, the increment of ṁDB, decreases the unavoidable exergy destruction just in high pressure steam turbine (HP.ST) and dearator (DEAR) by about 8.2% and 5%, respectively, and increases the exogenous of avoidable exergy destruction of DB (ĖD,DBAV) within 166%. It means that the effect of other components irreversibilities on avoidable exergy destruction of DB is increased while inefficiency of this component has considerable decrement on its avoidable exergy destruction.