Closed Cycle Gas Turbine Power Plant
Schematic diagram of a simple closed cycle gas turbine power plant is shown in Figure.
In this system the heat energy to compressed air is indirectly supplied in a heat exchanger called source. The heat energy of turbine exhaust gases is rejected in a heat exchanger called sink before supplied to the compressor.
Both the source and sink operate at constant pressure neglecting the pressure losses. Therefore, in this cycle the same working fluid (gas) is re-circulated and it remains uncontaminated by the products of combustion.
Advantages of the closed cycle are that it can use any type of fuel since heat is supplied externally to working fluid having the desirable properties (having high specific heat) without being contaminated. The system can be pressurized to reduce the size of components. It has higher output and efficiency as compared to open cycle power plant. However, the disadvantages of the system are that large sized heat exchangers are needed for its operation thus increasing its size and the cost. It has complexity of operation and system needs to be gas tight.