There are two definitions of exergy efficiency. i.e.
1. eff = Wnet/ Exergy In
2. eff= 1- (exergy destruction/ Exergy In )
While analyzing supercritical CO2 power cycles, the exergy efficiency from two definitions comes out to be different. There is almost a difference of 4 to 5%.
Kindly explain this?
I think the first definition includes also exergy lost but not the second definition.
The first one is based only on the difference of quality between energies and the second one focuses on irreversibility of the process.
Something might not be correct with the second definition. Exergy in minus exergy destroyed would not give you anything useful.
Dear Abubakr Ayub. I use the following approach to solve the problems of exergy efficiency - in the numerator - "useful" exergy, and in the denominator - "spent". This approach, I think, gives correct results.
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