An insight on intercooling and reheat gas turbine cycles

The current drive for high efficiencies and low emissions has resulted in the examination and development of advanced power systems based on complex gas turbine cycles. Reheat and intercooling are two such schemes. The basic objective of introducing intercooling and reheat is to increase specific power and thermal efficiency. When comparing ideal and real cycles, the largest sources of loss in a gas turbine engine are those arising from the turbomachinery and the need to cool the turbine blades. In this paper the concepts of intercooling and reheat for gas turbines are assessed, in a systematic way, using a model that includes the above losses in order to evaluate their effects on the engine performance. Also examined is the choice of the position where intercooling or reheat is implemented which can have a large effect on the engine output. A comparison is made with the simple cycle and it is shown that these schemes show much promise. Some of the development difficulties are also outlined. Intercooling promises large improvements in efficiency over the simple cycle, especially at high pressure ratios. Reheat on the other hand is much more suited to combined cycles.