Solving Thermodynamic Problem: Outlet Temp of Pipe Carrying Water

In summary, the speaker is seeking help with writing a formula to determine the outlet temperature of a pipe carrying water, given certain parameters. They mention using a heat transfer book and assuming constant temperature, but note that this problem is not typically described in a thermodynamics book. They offer assistance for any specific problems that may arise.
  • #1
rippir
1
0
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
 
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  • #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
jaap de vries said:
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
 

Related to Solving Thermodynamic Problem: Outlet Temp of Pipe Carrying Water

1. How do you calculate the outlet temperature of a pipe carrying water?

The outlet temperature of a pipe carrying water can be calculated using the formula: Tout = Tin + (Q/mCp), where Tout is the outlet temperature, Tin is the inlet temperature, Q is the heat transfer rate, m is the mass flow rate, and Cp is the specific heat capacity of water.

2. What factors affect the outlet temperature of a pipe carrying water?

The outlet temperature of a pipe carrying water is affected by several factors, including the inlet temperature, heat transfer rate, mass flow rate, and specific heat capacity of water. Other factors such as pipe material and insulation can also affect the outlet temperature.

3. How can I ensure accurate calculations when solving thermodynamic problems for a pipe carrying water?

To ensure accurate calculations, it is important to use the correct values for all variables, including the specific heat capacity of water at the given temperature and pressure. It is also important to consider any heat losses or gains in the system and account for them in the calculations.

4. Can the outlet temperature of a pipe carrying water exceed the inlet temperature?

Yes, the outlet temperature of a pipe carrying water can exceed the inlet temperature if there is a heat source along the pipe's length or if the pipe is insulated and there is minimal heat loss. However, in most cases, the outlet temperature will be lower than the inlet temperature due to heat losses in the system.

5. How can I troubleshoot if my calculated outlet temperature is significantly different from the actual outlet temperature in a real system?

If the calculated outlet temperature is significantly different from the actual outlet temperature, it is important to check all variables and values used in the calculation, including the specific heat capacity of water, mass flow rate, and heat transfer rate. It may also be helpful to consider any external factors that may be affecting the system, such as heat losses or gains, and adjust the calculations accordingly.

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