Heating of liquid when pressure 1bar-->5000bars

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Discussion Overview

The discussion revolves around estimating the temperature rise of a liquid when it is suddenly adiabatically pressurized from 1 bar to 5000 bars. Participants explore the implications of compressibility at high pressures and seek theoretical methods for calculation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Paavo Palikka expresses curiosity about the temperature rise of liquids under high pressure and questions how to calculate this effect, noting that the magnitude of temperature change is uncertain.
  • One participant shares an experience with a hydraulic system that reached 4480 bar without significant heating, suggesting that not much heat is generated from pressurization alone.
  • Another participant emphasizes the need for theoretical calculations and mentions the first law of thermodynamics, indicating that the pressure-volume-temperature (PVT) relationship is crucial for understanding the internal energy changes in the liquid.
  • A participant provides a generic compressibility value for water, which is questioned by another participant regarding its usefulness in the context of the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact temperature rise or the methods for calculation. There are multiple viewpoints on the heating effects of pressurization, with some experiences suggesting minimal heating while others seek theoretical frameworks for understanding the phenomenon.

Contextual Notes

Participants acknowledge that the behavior of liquids under extreme pressure may vary significantly based on the specific liquid and its properties, and that assumptions about incompressibility may not hold at such high pressures.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, fluid mechanics, or engineering applications involving high-pressure systems.

Paavo Palikka
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Hello!

I have some troubles finding a way to estimate how much temperature of liquid would rise when it is suddenly adiabatically pressurized to thousands of bars. In normal conditions liduids such as water are considered to be incompressible, but certainly not in 5000 bars. Because water (or any other liquid) gets compressed, also some heat should be generated. But how to calculate it and what are the constants? I am just curious about the magnitude of temperature rise, is it more like +0,1K, +1K or +10K. Of course this depends strongly on liquid, but I am interested of any liquid just to get idea how to calculate magnitude of temperature rise.



-Paavo Palikka
 
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(1) I once designed a one shot impact absorbing device for a large test rig .

Basically a piston in cylinder device using hydraulic fluid . When activated pressure in cylinder went in a fraction of a second from not much to somewhere in region of 65 000 psi . That's about 4480 bar . Hardly got warm .

(2) Hydraulic systems working at 10 000 psi (690 bar) are common and there are some systems working at very much higher pressures . Pumps generally get warm after a period of use but they don't normally get excessively hot . Most of the heating actually comes from the fluid passing through the valves and from bearing heating - not much comes from the actual pressurisation .
 
Thank you for your answer Nidum!

Even heat 1-->5000bar does does not get device warm, I would be interested how this could be calculated theoretically. I forgot to say that this is rather theoretical question,

.Paavo palikka
 
A "generic" compressibility for water is 30 ppm/atm.. Help you any?
 
Bystander: Not really, but thanks for trying to help.
 
Bystander's answer should really help. You just use the first law of thermodynamics, with the work equal to pdV. To do this, you need to have the PVT equation for the material, and this is where Bystander's answer comes in. You also need to look up the general equation for the effect of pressure on the internal energy of a material.

Chet
 

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