Thermodynamics - evaporator condenser

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SUMMARY

The discussion centers on the effects of increasing the flow of cooling water to a condenser in a multiple effect evaporator system. It is established that this increase leads to a reduction in condenser pressure, which subsequently lowers the pressure profile of the entire evaporator. Key factors include a constant heat transfer area, a slight increase in the overall heat transfer coefficient due to a higher Reynolds number, and a decrease in the cooling water outlet temperature. The relationship between these variables is crucial for understanding thermodynamic behavior in evaporator systems.

PREREQUISITES
  • Understanding of multiple effect evaporators
  • Knowledge of heat transfer principles
  • Familiarity with Reynolds number and its implications
  • Basic thermodynamics concepts related to pressure and phase changes
NEXT STEPS
  • Research the principles of heat transfer in condensers
  • Study the impact of flow rates on evaporator performance
  • Learn about the thermodynamic cycles in multiple effect evaporators
  • Examine the relationship between pressure and temperature in phase change processes
USEFUL FOR

Engineers, thermodynamics students, and professionals involved in designing or optimizing evaporator systems will benefit from this discussion.

James MEng
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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 occurring here I just cannot work out what!
 
Last edited:
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I'm wondering where it said that the outlet pressure from the condenser would be decreased. This doesn't seem reasonable to me.
 

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