The work output and rational efficiency of an open circuit gas turbine

The work output and rational efficiency of an open circuit gas turbine 

The statements on work output made for a real process (Eq. (2.23)) and for the ideal chemical reaction or combustion process at (po, Tq) (Eq. (2.37)) can be compared as 

The first equation may be applied to a control volume CV surrounding a gas turbine power plant, receiving reactants at state Rg = Ro and discharging products at state Py = P4. As for the combustion process, we may subtract the steady flow availability function for the equilibrium product state (Gpo) from each side of Eq. (2.47) to give 

This equation, as illustrated in the (T, s) chart of Fig. 2.8 for an open circuit gas turbine, shows how the maximum possible work output from the ideal combustion process splits into the various terms on the right-hand side  

Note that in Eq. (2.49) the term (Br Grq) does not appear as it has been assumed here that all reactants enter at the ambient temperature Tq, for which [—AGq] is known. For a compressed gaseous fuel, Grq) will be small but not entirely negligible. 

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