4 replies to this topic

[Anggun Rush]

 

Hello, I have one small issue about piping placement.

*Attached the sketch-up about the piping.

 

Now I do in option A. From cooling tower, cold water pumped to condenser through vertical pipe first and then horizontal pipe. When water through vertical pipe from top to the bottom gravity force will increase, but become decrease again when the water through horizontal pipe to condenser (pressure drop effect). The flowrate of water into condenser doesn't make the issue for condenser. 

 

But if I will change to option B, from cooling tower, cold water through horizontal pipe after near condenser, change direction through vertical pipe from top to bottom into condenser, so I think flowrate become larger because gravity force effect. 

 

For option B, Can I have any issue for condenser caused by gravity force, Water hammer, or pressure drop of water into condenser?

 

Thank you.

 

 

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[xavio]

anggun rush,

 

A and B have identical elevation difference, the "gravity force effect" you're talking is practically identical.

A and B also have roughly same total length of pipe, the frictional losses should be practically identical.

 

The flowrate at any point along the pipe is constant, so it is incorrect to say:

When water through vertical pipe from top to the bottom gravity force will increase, but become decrease again when the water through horizontal pipe to condenser (pressure drop effect).

 

What is changing along the pipe is pressure, not flowrate.

Assuming you have centrifugal pump there, the flowrate is determined by total differential head of your system.

Because there is no difference in elevation and pipe length for A and B, it is safe to say that your pump will produce just the same flowrate for both cases.

 

As for water hammer, you don't need to worry about it.

You are pumping subcooled liquid, water hammer is not an issue.

Just check your in-pipe velocity to avoid erosion.

 

Hope it helps.

 

xavio

[katmar]

There is not enough information in your query to be able to give a definitive answer.  What are the pipe lengths, elevation differences, pipe sizes and flow rates?  Does the water exiting the condenser return to the same level as the supply pump?

[Anggun Rush]

Hi Xavio,

 

So, no different between model A & B about gravity force, pressure drop, or water hammer.

Thank you, I dont think about the velocity before.

[xavio]

anggun rush,

 

Yes, but as katmar pointed out, details matter.

You should perform hydraulic calculation for both cases to get the final answer.

At a glance, piping design for option B looks awkward.

 

Undersized pipe diameter might bring erosional problem to single-phase flow like this.

However, most of the time frictional losses reach an uneconomical level far before the erosional velocity is reached.

 

Good luck.

 

xavio