Why rankine cycle used instead of carnot cycle in stream power plant?
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Carnot Cycle is the most fundamental cycle in Thermodynamics. Moreover, it is an ideal cycle consisting four processes (most simply) as follows:
Heat input to the system
Work output
Heat rejection by the system
Work input to the system
These processes in power plant are done by following devices respectively.
Boiler
Turbine
Condenser
Pump
We know that the processes by these devices will not be ideal and involve some losses.
It is true that Carnot Cycle is the best cycle with the highest efficiency. So we should make our processes as nearer to these ideal processes to achieve high efficiency. But this does not work in cases of power plants.
Heat addition in power plants is at constant pressure whereas it is constant temperature process in Carnot Cycle which is not easily achievable.
Carnot cycle work input (analogous to pump work in power plants) is very large, while in Rankine cycle, it is comparatively little.
That is why we don’t go for Carnot cycle in power plants but use a more practical Rankine Cycle.
Heat input to the system
Work output
Heat rejection by the system
Work input to the system
These processes in power plant are done by following devices respectively.
Boiler
Turbine
Condenser
Pump
We know that the processes by these devices will not be ideal and involve some losses.
It is true that Carnot Cycle is the best cycle with the highest efficiency. So we should make our processes as nearer to these ideal processes to achieve high efficiency. But this does not work in cases of power plants.
Heat addition in power plants is at constant pressure whereas it is constant temperature process in Carnot Cycle which is not easily achievable.
Carnot cycle work input (analogous to pump work in power plants) is very large, while in Rankine cycle, it is comparatively little.
That is why we don’t go for Carnot cycle in power plants but use a more practical Rankine Cycle.
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