Differential Pressure Across Chiller Barrels 1

[DRWeig]

Hi Team,

Under near-laboratory conditions and with very accurate instruments, I'm measuring flow through both chilled and condenser water barrels of a chiller. Instead of the expected flow-squared correlation to pressure drop, I'm getting flow to the 1.7 or 1.8 power.

Anyone here ever run into this? I would think that a chilled water tube bundle would behave like a long straight run of pipe and give me flow-squared correlating to pressure drop.

Am I missing something here?

Thanks much!

Best to you,

Goober Dave

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[MTES93]

I had to go look at Bernie's equation again then to Hazen Williams - then to Darcy Weisbach... Talk about taking a trip in the way back machine.

In Darcy which is considered the more accurate of the two, friction is related to the square of the velocity which we would expect... I wonder if it is the actual friction coefficient of the 'pipe' which changes w/Reynolds number??? I think it can change significantly depending on flow regime you are in... laminar transitional and turbulent which obviously impacts your loss/flow relationship...

I know in the simpler hazen willians they use a somewhat fixed friction value (I think based on pipe type) rather than the calculated f value that Darcy uses. In the Hazen formula, friction loss varies with 1.85 power of the flow/velocity...

Hope this helps.

 

[DRWeig]

Thanks 11241, that gives me a good place to start.

Dave

Best to you,

Goober Dave

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[DRWeig]

From 11241's hints, I found good data here:

http://www.crses.sun.ac.za/files/research/completed-research/solar/thesis_olivier_UP.pdf

among other places, for those of you who might be interested...

Best to you,

Goober Dave

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