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Water under pressure and temperature effects

  1. May 25, 2012 #1
    If you apply tremendous force to water and cause extremely high pressure, it should compress and the temperature should go up - but if the heat is given away to the surroundings, does the water temp continually go up to match the surroundings? does the water temp go down underneath the surrounding temp? I would think that initially the water would give off some heat, but does this mean the water is colder since it has given off heat? And if it's colder, won't it just have to regain the heat again to match the surrounding temp. Seems confusing.
     
  2. jcsd
  3. May 26, 2012 #2
    I would think that the temperature rise would be related to the amount of work that one would have to put into the water to compress it. Since the change in volume of water per change in pressure is not very much there would be little work performed and the temperature rise would be very little.
     
  4. May 26, 2012 #3

    haruspex

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    I agree there should be very little change in temperature, but for a different reason. Given that large forces are needed to compress water, even a little compression may take significant work. But on release, I believe much of the energy would be recovered. If so, it means the work done was stored in the state of compression rather than as heat.
    See e.g. http://www.criticalprocesses.com/Use of enthalpies to calculate energy needed.htm
     
  5. May 26, 2012 #4
    If you are talking about extreme pressures, then water is more compressible than most folks think. If you are not familiar with the concept of a bulk modulus, go look it up. Think of it as a sort of poison ratio for a liquid, and you can use it in a similar manner as calculating strain energy. This is the energy you are talking about. Once you run the numbers, you will see that the amount of work done is relatively small.
     
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