Chapter 13 Gas Turbine Power Plants

Q A =C p (T 03 -T 02 .) (13.14)
where T 02 - is calculated from (13.10), i.e.,
(13.15)
Finally, the cycle thermal efficiency T] can be calculated by
substituting the above equations into the equation,
W -W
^ = ^-^- (13.16)
where the numerator has been expressed as a difference, since W c
represents the magnitude of the compressor work.
The graphs of Figure 13.3 were determined by using the
methods outlined above. The variation of cycle thermal efficiency
with cycle pressure ratio at constant turbine inlet temperature is
shown for the air standard Brayton cycle with y = 1 .4. It is noted
that the optimum cycle pressure ratio is a function of turbine inlet
temperature. For T 03 =1000°K the optimum r p is around 7 or 8,
but for T 03 = 1300°K the optimum r p is much higher. Cycle efficiency
depends on turbine inlet temperature and cycle pressure
ratio; furthermore, there is an optimum pressure ratio for every
turbine inlet temperature.
13.4 Brayton Cycle with Regeneration
Efficiency as a function of cycle pressure ratio for a cold airstandard
Brayton cycle having T 03 = 1300°K was considered in