Heat exchanger - efficiency of the cycle

AI Thread Summary
The discussion centers on the efficiency of a heat exchanger cycle, particularly concerning the state of the working fluid before entering the boiler. It highlights that if the fluid's temperature exceeds 374°C after expansion, the condenser must reject sufficient heat to maintain the fluid in a liquid state, impacting cycle efficiency negatively. Participants express curiosity about the implications of high temperatures in power cycles and request a TS diagram to illustrate the process, especially through the condenser. The conversation emphasizes the importance of understanding vapor-liquid equilibrium in this context. Overall, the efficiency of the cycle is closely linked to the temperature management of the working fluid.
EastWindBreaks
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Homework Statement


T-s-Diagram-of-Vapour-Power-Cycle.png

Homework Equations

The Attempt at a Solution


Since we want the fluid to be in liquid state before entering a boiler, and super-heated water can only reach 374°C before entering super-critical state, suppose after the expansion, the temperature at point 3 is still higher than 374°C, does that mean the condenser must still reject enough heat to ensure the working fluid is in liquid form, since Q_out is large, the efficiency of the cycle won't be as good?
 

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Let's see what your concept of the process looks like if the temperature at point 3 is above the critical temperature. Please show us the TS diagram, also showing, for reference, the vapor-liquid equilibrium region.

Is this really a homework problem?
 
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Chestermiller said:
Let's see what your concept of the process looks like if the temperature at point 3 is above the critical temperature. Please show us the TS diagram, also showing, for reference, the vapor-liquid equilibrium region.

Is this really a homework problem?

its not a homework problem, I was just curious while reading about the textbook chapter on power cycles, since it is desirable to have high temperature input, I was thinking maybe that temperature can be so high that the temperature of the fluid coming out of the turbine might able to reach above 374 Celsius ?
 
EastWindBreaks said:
its not a homework problem, I was just curious while reading about the textbook chapter on power cycles, since it is desirable to have high temperature input, I was thinking maybe that temperature can be so high that the temperature of the fluid coming out of the turbine might able to reach above 374 Celsius ?
OK. So let's see your TS diagram of the cycle. I'm particularly interested in the part of the path through the condenser (or cold sink).
 
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