Unit-6: Heat Engines: Gas turbines

In a gas turbine, the gaseous products of combustion are typically around 1300oC. The turbine blades are covered by a ceramic coating of low thermal conductivity.
Gas turbines for electricity generation originally evolved from jet turbine engines.
Since the working fluid does not change phase, a condenser is not involved in the process, so the overall size and cost of a gas turbine plant is less than that of an equivalent steam plant.
Gas turbines operate in a Brayton (or Joule) cycle. It is an open cycle but is equivalent to a closed cycle in the sense that the atmosphere acts as a heat exchanger that cools the air entering the combustion chamber.
Gas turbines are relatively low capital cost devices that can be started up quickly and are employed for satisfying sudden changes in electricity demand.
Efficiencies of simple gas turbines are up to around 40%.