Handbook of Turbomachinery Second Edition Revised - Ventech!

Figure 1 Trend or growth for key engine operating parameters.
the last stages of a compressor rotor, considering that temperature
capability of the material for these components is limited to about 700 8C
(1,300 8F). Application of a lower-temperature air from an intermediate
compressor stages can be beneficial if this air has a sufficient pressure
margin over the exterior pressure of the cooled component. In some cases,
the temperature of the discharge air can be reduced in an external heat
exchanger, for example, using in the cooling circuit a low-temperature
bypass air in aero engines or water in combined cycle industrial turbines.
A closed cooling system, where the coolant continuously circulates in a
closed loop, presents a more efficient but more complex alternative to the
open system. Closed-loop systems using liquid metal coolants are known for
space application. A closed-loop steam cooling system that had been tried
decades ago is regaining its popularity for heavy-duty industrial gas
turbines, particularly in combined cycle power generation plants.
Advancements in cooling technology are a critical means, together
with improvements in high-temperature materials, to achieve higher turbine
inlet temperatures. Cooling systems must be designed to assure that the
maximum component temperatures and temperature gradients experienced
Copyright © 2003 Marcel Dekker, Inc.