Water-air composite pressure system

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SUMMARY

The discussion centers on the energy calculations of a water-air composite pressure system. The user compares the energy stored in three systems: an air tank at 10 bar pressure with 1000 KJ, a water tank with 5.04 KJ, and a composite system containing both water and air. The calculations suggest that the total energy in the composite system is 50900 KJ, derived from both the water and the air under pressure. The user seeks clarification on the accuracy of these calculations and the significant difference in energy values.

PREREQUISITES
  • Understanding of thermodynamics, particularly energy storage in gases and liquids.
  • Familiarity with pressure units, specifically bar and its conversion to height in water.
  • Knowledge of isothermal expansion principles in gas behavior.
  • Basic concepts of hydraulics and fluid mechanics.
NEXT STEPS
  • Review the principles of energy conservation in fluid systems.
  • Study the calculations involved in isothermal expansion of gases.
  • Learn about the relationship between pressure, volume, and energy in hydraulic systems.
  • Explore advanced topics in hydraulics to understand energy differences in composite systems.
USEFUL FOR

Engineers, physicists, and students studying fluid mechanics, thermodynamics, or hydraulics, particularly those interested in energy calculations in composite pressure systems.

apurvmj
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Hi all,
This is my first post since I'm unable to find the answer myself & on the net too.
My query is let's consider we have 3 types of system

1. Air tank at 10 bar pressure.
It will have105*10*1= 1000 KJ energy.

2. Water tank of volume 1 cum and height of 1 m.
It will have 5.04*h2 = 5.04 KJ (h= water head pressure)

3. Now let's say we have 2 cum of volume containing water of 1 cum and 1 cum air at 10 bar.
can I say we have energy in water= 5.01*1002 = 50400 KJ (10 bar=100 m of water)
plus when water is out of tank volume of air will be 2 cum at 5 bar.
then energy stored in air (considering isothermal expansion)= 500 KJ
so total 50900 KJ.

Am I doing wrong some where/ everywhere then where is it wrong?
If not why there is so diffrence in energy?
 
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Pls help.
Don't anyone here study hydraulics.
 

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