The irreversible recuperative cycle

For the closed recuperative cycle [CHTXJi, with states 1,2,X,3,4, Y as in the T,s diagram of Fig. 3.10, the net specific work is unchanged but the heat supplied has to be reassessed as heat qj is transferred from the turbine exhaust to the compressor delivery air. Using the heat exchanger effectiveness, e = (Tx — — Ti) the heat supplied 

The isentropic temperature ratio for maximum efficiency (x ) is again obtained by writing dp/hx = 0 after some algebra this yields 

For the [CHTXJi plant, with the cycle parameters quoted above for the [CHTJi plant  

For their graphical interpretation, Hawthorne and Davis wrote 

The graphical representation is not as simple as that for the [CHTJi cycle, but still informative. It is also shown in Fig. 3.8, which gives a plot of the [CHTXJi efficiency against x for the parameters specified earlier, and for e = 0.75. The term in the square 

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