Dryness fraction - is anything missing here ?

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Homework Help Overview

The discussion revolves around the concept of dryness fraction in thermodynamics, specifically in the context of steam properties in a closed vessel and an ideal Rankine Cycle. Participants are exploring calculations related to steam mass and dryness fraction under varying pressures.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to calculate the mass of steam and final dryness fraction in a closed vessel as well as the dryness fraction at the turbine exhaust in a Rankine Cycle. Questions about determining temperature from steam tables and the significance of the term "saturated" are raised.

Discussion Status

Some participants have provided hints regarding the use of steam tables to find necessary properties, while others are questioning the assumptions and definitions involved in the problem setup. There is an ongoing exploration of the implications of the conditions described.

Contextual Notes

Participants are discussing the importance of steam tables and the implications of the term "saturated" in relation to the calculations. The context includes specific pressures and conditions that may affect the outcomes of the calculations.

rmenon
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dryness fraction - is anything missing here ??

Hi Guys,
Got a couple of questions I need answers on.
a)A closed vessel of 0.8 m3 capacity contains dry saturated steam at 350 kPa. The vessel is cooled until the pressure is 200 kPa. Calculate
1) mass of steam in the vessel
2) final dryness fraction

b)A steam plant that operates on the ideal Rankine Cycle produces steam that is dry and saturated at 500 kPa. The condenser pressure is 20 kPa. Calculate the dryness fraction at the turbine exhaust (expansion is isentropic)
What is the work done per kilogram of steam ?

Thanks and regards
Raj
 
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rmenon said:
Hi Guys,
Got a couple of questions I need answers on.
a)A closed vessel of 0.8 m3 capacity contains dry saturated steam at 350 kPa. The vessel is cooled until the pressure is 200 kPa. Calculate
1) mass of steam in the vessel
2) final dryness fraction
Can you determine the temperature of the steam in a)? Hint: the word "saturated" is important.

AM
 
Do you mean from steam tables
 
rmenon said:
Do you mean from steam tables
Well, you could boil water at 350 kpa and see what temperature it boils at. Or you could just look it up in a steam table.

AM
 

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