Fluid's boiling point dependence as function of pressure

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SUMMARY

The boiling point of fluids is directly dependent on pressure, particularly in pressurized water reactors (PWRs) where water is maintained at high pressure to prevent boiling. The saturation temperature increases with pressure, and empirical correlations exist for both saturation temperature and heat transfer coefficients. In PWRs, the coolant typically remains subcooled, with a core inlet temperature below the saturation temperature, leading to potential nucleate boiling as the coolant approaches the saturation temperature. A pressure drop of approximately 25 psid occurs across the PWR core, affecting the boiling dynamics.

PREREQUISITES
  • Understanding of saturation temperature and pressure relationships
  • Familiarity with pressurized water reactor (PWR) operations
  • Knowledge of empirical correlations in heat transfer
  • Basic concepts of nucleate boiling and fluid properties
NEXT STEPS
  • Research the Jens-Lottes correlation for subcooled nucleate boiling
  • Study steam tables to analyze saturation lines and boiling point relationships
  • Explore empirical correlations for heat transfer coefficients in fluids
  • Investigate the effects of pressure drop in PWR systems on boiling phenomena
USEFUL FOR

Engineers, nuclear reactor operators, and thermal hydraulic specialists interested in fluid dynamics and boiling point behavior in high-pressure systems.

Stephan_doc
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Greetings to all,
I need some help for i understand how to demonstrate fluids boiling point dependence as function of pressure (i.e for main cool agents). Which are the basic equations for to write a general formula? I know that in PHWR type reactor water is at height pressure to prevent boilling phenomena.
Thanks a lot
 
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I don't know about a general formula, but if you consult the saturation line in any handy steam tables, you can discern a relationship between boiling point and pressure.
 
Generally, pressurized water reactors have a core inlet temperature which is subcooled, i.e., Tcoolant < Tsat. By the time the coolant about 70% of the way through the, it is possible that sub-coolant nucleate boiling occurs, i.e., the cladding surface reaches or slightly exceeds the saturation temperature. One also must bear in mind that there is a pressure drop of about 25 psid across a PWR core.

As pressure increases, the saturation temperature increases, and there are empirical correlations for that, just as there are empirical correlations for heat transfer coefficients and fluid properties. Material properties are generally not defined ab initio.


Here are some notes on the Jens-Lottes correlation for subcooled nucleate boiling.
http://www4.ncsu.edu/~doster/NE400/Text/HeatConvection/Boiling.PDF
 

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