Search This Blog

Tuesday, 1 April 2014

Advantages and Disadvantages of Closed Cycle Over Open Cycle

Advantages and Disadvantages of Closed Cycle Over Open Cycle Points : Advantages and Disadvantages of Closed Cycle Gas Turbine Over Open Cycle Gas Turbine, Advantages and Disadvantages of Closed Cycle Over Open Cycle
Advantages of Closed Cycle Over Open Cycle
Closed Cycle
Open Cycle
1.As the working fluid does not mixed with the products of combustion therefore it is possible to use a gas of higher density and higher specific heat then air such as krypton, argon" xenon etc. This will reduce the size of the various components. Helium has been successfully used as working medium in closed cycle gas turbines. The specific heat of helium at constant pressure at being nearly five times that of the air so heat drops and hence energy delta per kg of mass flow in about five times in turbines using air heat exchanger sued in glass turbines using helium as working medium less surface area of about 1/3 that of heat exchanger used in gas turbines using air as working medium. Therefore the size of helium unit is comparatively smaller.But in case of open cycle system working fluid mix with the product of combustion land large amount of air is necessary in it and we can't used gas of higher density that is why this system part load performance is low that's why the closed cycle system. Is more advantages than open cycle system. If we are using gas (helium) as working medium therefore the size helium unit is combatively 1/3 smaller than open cycle's combustion chamber this thing reduce the size of the various component. Which is the main characteristic of the system is.
2.As the working medium does not mix with the product of combustion so there is no accumulation of carbon deposits on blade and nozzles of the turbine. The compressor remain free of dust as the working medium may be cleaned. Therefore, the periodic cleaning of component is not needed.But increase of open cycle system the working medium mix with the product of combustion so there is necessary the accumulation of carbon deposits on blade and nozzles of the turbine which get dusty the compressor therefore the periodic cleaning is must in open cycle system.
3.The system has improved part load efficiency as the output can be varied by withdrawing or admitting more working medium.Part load performance of open cycle system is low because there is a limit of admitting air in the compressor. Because air is heavy than helium
4.External heating can be done by inexpensive solid fuels such as coal.
Disadvantages of Closed Cycle Over Open Cycle
Closed Cycle
Open Cycle
1.As the system is under an initial high pressure with a working medium other than air, therefore the system should be gastight. This increase the cost of the system.In open cycle system the combustion chamber is lighter in weight and smaller in size with a high rate of heat release that's why the system is quit cheaper then closed cycle system.
2.A large air heater is needed and this air heater is not as sufficient as the combustion chamber used in open cycle.The combustion chamber of open cycle system is more efficient and suitable for large quantity of air.
3.As the system needs cooling water so the system cannot be used in aeronautical engines.Cooling water is not needed to except in those turbine using intercooler. This property is quite advantages in marine aviation etc.

No comments:

Post a Comment

Dont paste link here..