Thermodynamic problem

  • Thread starter rippir
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Hi,
after a while of searching through a thermodynamics book and not really finding what I'm looking for I come to you all with my problem :D

Here it is:
I am required to write a formula which will allow me to determine the outlet temperature of a pipe carrying water for any given flow rate, diam, length, inlet temp, ambient temp.

So for a sample problem, if water enters a 5m long 0.02m diameter pipe at 40 degrees C & travels through the pipe @ 3 m/s and the ambient temperature is 20 degrees C, what temperature will the water at the outlet be?

For the time being, I would like to assume that the pipe which the water is flowing through is constantly 20 degrees due to ambient temperature.

The purpose of this problem is to know how long a pipe in a HVAC system can be before the water reaches ambient temperatures

Any help is greatly appreciated.
Cheers!
Daniel
 

Answers and Replies

  • #2
This sound like a heat transfer problem and specifically convection heat transfer. As always with heat transfer problems the trick is in the assumptions you could assume the pipe to naturally convect into the ambient air but this seems overkill. Just pick up a undergraduate heat transfer book and go to the convection heat transfer section. Remember that the flow might not be fully developed at the entrance (although you might get away with assuming this).
This is not a problem that is typically described in a thermodynamics book!


Let me know if you run into specific problems.
 
  • #3
This sound like a heat transfer problem and specifically convection heat transfer. As always with heat transfer problems the trick is in the assumptions you could assume the pipe to naturally convect into the ambient air but this seems overkill. Just pick up a undergraduate heat transfer book and go to the convection heat transfer section. Remember that the flow might not be fully developed at the entrance (although you might get away with assuming this).
This is not a problem that is typically described in a thermodynamics book!


Let me know if you run into specific problems.

yes i agree
 

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