Heat exchanger - efficiency of the cycle

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Homework Help Overview

The discussion revolves around the efficiency of a heat exchanger cycle, particularly focusing on the state of the working fluid and its temperature relative to critical conditions. Participants explore the implications of superheated water and the necessity of maintaining the fluid in a liquid state before entering the boiler.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question the relationship between the temperature of the fluid at various points in the cycle and the efficiency of the heat exchanger. There is a request for a TS diagram to illustrate the process and the vapor-liquid equilibrium region. Some participants express curiosity about the implications of exceeding critical temperatures in the context of power cycles.

Discussion Status

The discussion is ongoing, with participants sharing their thoughts and seeking clarification on the concepts involved. There is an interest in visual representations of the cycle, and while some participants indicate that the problem may not be strictly homework-related, the exploration of the topic remains productive.

Contextual Notes

Some participants note that the inquiry stems from curiosity about textbook material rather than a formal homework assignment, which may influence the depth of the discussion and the types of questions raised.

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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