See Also: Combined Cycle, States Of Matter, Rankine Cycle
The processes used in the Brayton Cycle are:
a to b: Isentropic (constant Entropy) compression in the compressor.
b to c: Constant Pressure Heat addition in the combustor.
c to d: Isentropic expansion in the turbine.
d to a: Constant pressure heat rejection.
The thermal efficiency of the Brayton Cycle can be calculated in two ways.
One, (Q(in) - Q(out))/Q(in). Two, (W(turbine) - W(compressor))/Q(in). Q stands
for heat, and W stands for work.
Most Combustion Turbines use the Brayton Cycle, which is an Internal Combustion (see Internal-Combustion Engin
e) cycle. Combustion cycles differ from vapor power cycles, such as the
Rankine Cycle, in that combustion products cannot be returned to their initial
conditions for reuse. In most vapor cycles water is converted to steam, then back to
water, and then used again. Almost all installations drive the Compressor off of the Turbine.