Comparison Between Closed Cycle Gas Turbine and Open Cycle Gas Turbine

Comparison Between Closed Cycle Gas Turbine and Open Cycle Gas Turbine can be done in 11 different criterias. Those 11 criterias are cycle of operation, working fuel used, type of fuel used, manner of heat input, quality of heat input, efficiency, part load efficiency, turbine blade life of a turbine, control on power production and cost of turbine plant installation compared in below table briefly.

S.no
Criterion
Closed Cycle Gas Turbine
1 Cycle of operation It works on closed cycle. The working fluid is recirculated again and again. It is a clean cycle. It works on open cycle. The fresh charge is supplied to each cycle and after combustion and expansion. It is discharged to atmosphere.
2 Working fluid The gases other than the air like Helium or Helium-Carbon dioxide mixture can be used, which has more favourable properties. Air-fuel mixture is used which leads to lower thermal efficiency.
3 Type of fuel used Since heat is transferred externally, so any type of fuel; solid, liquid or gaseous or combination of these can be used for generation of heat. Since combustion is an integral part of the system thus it requires high quantity liquid or gaseous fuel for burning in a combustion chamber.
4 Manner of heat input The heat is transferred indirectly through a heat exchanger. Direct heat supply. It is generated in the combustion chamber itself
5 Quality of heat input The heat can be supplied from any source like waste heat from some process, nuclear heat and solar heat using a concentrator. It requires high grade heat energy for generation of power in a gas turbine.
6 Efficiency High thermal efficiency for given lower and upper temperature liquids. Low thermal efficiency for same temperature limits.
7 Part load efficiency Part load efficiency is better. Part load efficiency is less compared to Closed cycle gas turbine.
8 Size of plant Reduced size per MWh of power output. Comparatively large size for same power output.
9 Blade life Since combustion products do not come in direct contact of turbine blade, thus there is no blade fouling and longer blade life. Direct contact with combustion products, the blades are subjected to higher thermal stresses and fouling and hence shorter blade life.
10 Control on power production Better control on power production. Poor control on power production.
11 Cost Closed cycle gas turbine plant is complex and costly. Open cycle gas turbine plant is simple and less costly.

Vinodh Reddy is an Editor-in-chief of ME Mechanical. He holds Bachelor of Engineering (Honours) degree in Mechanical Engineering from BITS-Pilani. He also writes for vrcworks.net and EduGeneral.

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