Finding resulting pressure in a pipe when water is heated

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Discussion Overview

The discussion revolves around the relationship between water temperature and pressure in a closed pipe system, particularly focusing on how heating water from 5 to 90 degrees Celsius affects static pressure. The scope includes theoretical considerations and practical applications related to pressurized pipe systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks an equation linking water temperature and pressure in a closed system, noting that heating water causes it to expand and increase static pressure.
  • Another participant questions whether the pipe contains only water or if there is gas present, and whether the pipe itself can expand when heated.
  • It is mentioned that the system typically operates at 1-5 bars of gauge pressure and involves regular steel pipes, raising uncertainty about the relevance of pipe expansion.
  • Participants inquire about the coefficients of volumetric thermal expansion for both steel and water, indicating a need for these values in calculations.
  • One participant expresses uncertainty about how to apply the coefficients of thermal expansion and emphasizes the importance of understanding "volumetric coefficient of thermal expansion" and "bulk compressibility" for solving the problem.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the application of thermal expansion coefficients or the relevance of pipe expansion in this context. Multiple viewpoints and uncertainties remain regarding the factors influencing pressure changes in the system.

Contextual Notes

Participants have not fully defined the assumptions regarding the system's conditions, such as whether the pipe can expand and the specific properties of the materials involved. There is also a lack of clarity on how to apply the thermal expansion coefficients in practical scenarios.

TSN79
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I work with pressurized pipe systems, and so I'm looking for some equation that link water temperature and pressure. In other words, when water in a closed system is heated, it expands, and so the static pressure increases. A typical problem will be determining the resulting pressure in a piece of pipe if the water in it is heated from say 5 to 90 degrees. Any ideas?
 
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TSN79 said:
I work with pressurized pipe systems, and so I'm looking for some equation that link water temperature and pressure. In other words, when water in a closed system is heated, it expands, and so the static pressure increases. A typical problem will be determining the resulting pressure in a piece of pipe if the water in it is heated from say 5 to 90 degrees. Any ideas?
Does the water fill the pipe, or is there gas also? Can the pipe expand also when heated, or is it just the water?
 
Chestermiller said:
Does the water fill the pipe, or is there gas also? Can the pipe expand also when heated, or is it just the water?

There is only water, usually at 1-5 bars (gauge pressure). We mostly deal with regular steal pipes (SCH 20, 30, 40) up to DN150 so I'm not sure if pipe expansion is a factor to consider?
 
TSN79 said:
There is only water, usually at 1-5 bars (gauge pressure). We mostly deal with regular steal pipes (SCH 20, 30, 40) up to DN150 so I'm not sure if pipe expansion is a factor to consider?
What is the coefficient of volumetric thermal expansion of steel, and what is the coefficient of volumetric thermal expansion of water?

Chet
 
Chestermiller said:
What is the coefficient of volumetric thermal expansion of steel, and what is the coefficient of volumetric thermal expansion of water?

Chet

They can both be found in the link, but I'm still not sure how to apply these values.

http://en.wikipedia.org/wiki/Thermal_expansion#Volume_expansion
 
TSN79 said:
They can both be found in the link, but I'm still not sure how to apply these values.

http://en.wikipedia.org/wiki/Thermal_expansion#Volume_expansion
I'd like you to be able to figure this out by yourself. I'm prepared to keep you pointing in the right direction.

Please tell me you understanding of the physical meaning of "volumetric coefficient of thermal expansion" and "bulk compressibility"? Understanding of both of these quantities will be necessary to solve your problem. If you aren't sure of their meaning, please look them up, and then get back to me with your understanding. If you have any questions about them, I will be glad to answer them.

Chet
 

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