Water Drain Channel minimal cross-section

[addibigg]

TL;DR

Drain channel minimal cross-section

Hi there!
I'm looking for an approx. minimal size for a drain channel where condensation water can go through. Can anyone have some advice?
No increased pressure for the water, just the normal atmospheric pressure. Water condensing and just have to be able to get out.
The amount of water is small, let's say 50-100ml/hours.

Attached the first draft of the channel. Smallest cross-section:

Any standards (if exists) could be good too, so I can refer to it.

Thanks!
Regards,
Ádám

 

[jack action]

Maybe Manning's equation is of interest to you?

 

[Rive]

TL;DR Summary: Drain channel minimal cross-section

let's say 50-100ml/hours

That's around a dripping tap. Unless it's some really special area of application I would not try to overthink this.

Without knowing the area of application, it's hard to talk about requirements...

My only thought about this is that stale water often prone to biological activity => clogging => you may need to provide means for cleaning.

 

[Baluncore]

Without knowing the area of application, it's hard to talk about requirements...

My only thought about this is that stale water often prone to biological activity => clogging => you may need to provide means for cleaning.

True.
If the area is not subjected to UV sunlight, consider waxing the surface, so beads of water then run off cleanly.

 

[jrmichler]

That could be a challenging problem. In order for water to flow, there must be a pressure difference. That difference can be quite small, but it must have a downhill gradient. For example, the gradient of the Mississippi River is only a few inches per mile. Mechanical engineers refer to the gradient as head loss.

Flow vs head loss is calculated using a Moody chart (search the term). You will find that you have a very low Reynolds Number, so you may need to calculate it using the equation on the chart for friction factor in laminar flow.

Your flow channel is not a round pipe running full, so you will need to calculate the hydraulic radius (another term to search), and use that number in the head loss equation. Interesting side note: In some circumstances, a round pipe will flow more water when partly full than when running full. This is a very real situation in culvert flow.

At the size of the flow channel, water surface tension will be significant. The water may not want to enter the channel at all. You may need some way to accumulate enough water that the pressure head will push it into the channel. Or add some soap to reduce surface tension. Or make the channel from a material that bonds to water so that it does not bead up. This calls for some experiments.

 

[Baluncore]

Or make the channel from a material that bonds to water so that it does not bead up. This calls for some experiments.

There are always too many possible solutions to an under-specified problem.
A wick could lead the water over a ridge, like a siphon, while an area of felt could evaporate a condensate back into the air.