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Thermodynamics - evaporator condenser

  1. Oct 31, 2013 #1
    Hello - fundamental thermo question which is puzzling me...

    It concerns a multiple effect evaporator with condenser. Hot vapour is water, cooling medium is water.

    My question stems from the following:
    When the flow of cooling water to the condenser is increased, the pressure in the condenser (and thus the pressure profile of the entire evaporator) is reduced.

    Here's how I understand it...

    • Heat transfer area of condenser remains constant
    • Overall heat transfer coefficient is increased slightly; given that the Reynolds number on cold side is increased
    • Cooling water temperature out is reduced (assuming heat load is constant and inlet temperature is the same)

    How does this in turn lead to a reduction in evaporator pressure, please explain in basic terms (what's actually physically happening rather than just formulae! :thumbs:).

    Thanks in advance for any replies

    Edit: Also the mass flow rate of condensate will be the same for a given flow "in" of water and steam. Some thermodynamic activity is occuring here I just cannot work out what!
    Last edited: Oct 31, 2013
  2. jcsd
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