A visual on flow transition in pipes

hot_rod

This display allows me to demonstrate air, dirt, magnetic separation and also show flow changes as pumps ramp up and down in speed. A small aquarium air pump allows for air removal demo. 409 stainless steel chips work good for a magnetic separation demo, and they don't rust.

At flow rates in excess of 2 fps, as predicted by the formulas, you can see the water display a sort of multiple "cork screw" patterns through the pipe. As you slow flow the fluid "screw" patterns stretch out, and slow down and less movement is seen.

Eventually the flow appears to stop moving, at flow rates below about 1 gpm as best as I can measure. Injecting some air show a small movement in the core of the tube, bubbles actually stop moving and cling to the wall of the tube.

The pumps adds heat to the loop when you run it for an hour or so, at low flow rates you can feel then pipe wall is cooler that at the 2 fps flow rate, indicating the heat transfer is tied directly to flow velocity.

You can also see the action inside the closely spaced tees, and the reverse flow or two direction flow as you vary the primary and secondary flow rates. In this pic secondary glow is going up, primary flowing down.

Inject large air and you can see the effect of cavitation in the clear plastic pump bodies.

A poor mans 0-10VDC control via a 9 V battery.

It's a little tough to get on a plane, else I would take it to all training classes.
A clear fire tube boiler demo would be nice to add.

img src="https://us.v-cdn.net/5021738/uploads/editor/dp/vfg247f52g9m.png" alt="" />

Canucker

@hot rod Do you have a video of it in action? I would love to see it. That might be something you can tote around easier than the set up. I seem to remember someone linking to a steam set up made of glass, which was fascinating to watch

hot_rod

Canucker said:

@hot rod Do you have a video of it in action? I would love to see it. That might be something you can tote around easier than the set up. I seem to remember someone linking to a steam set up made of glass, which was fascinating to watch

Good idea, a neighbor is a photographer, he may have a better setup to film it in action. Be a fun You Tube project.

This is acrylic, it starts to squirm at warm temperatures, glue joints don't care for pressure and temperature, lots of JB weld repairs on those large pieces. I keep a large towel and bucket on standby when I take it on the road.

This is a portable version for our reps, air, dirt, mag separation with an air pump.

Canucker

Clear PTFE might work? Joints would probably still be an issue, I've personally never seen it heat welded together but I'll bet Swagelok has fittings

hot_rod

Canucker said:

Clear PTFE might work? Joints would probably still be an issue, I've personally never seen it heat welded together but I'll bet Swagelok has fittings

I've tried a few different plastic tubes. Clear PVC is to purple colored, some of the poly and acrylics are not CTS so fittings are a problem.
With this acrylics, I heat it with a heat gun to make sweeps, save on fittings. It is glue-able with a cement like you use for models, but no fittings.

The shark bite fittings allow you to disassemble and reuse them and the tube. I router a piece of plywood to make a template to bend the ells and 180 bends.

Various wall thickness available also. US Plastic in Ohio is a good source for all things plastic, quick shipping and small quantity orders are accepted.

Harvey Ramer

That's some pretty cool stuff bob! Nothing speaks louder than seeing physics in real time!

Solid_Fuel_Man

I like it! When I was in college, we built a trainer out of acrylic for the different industrial valves and flow meters. It was fun, but was all an open drain down system. Had many pneumatics and 4-20ma transducers performing various functions. Closed loops hydronic would be more fascinating to watch!

TS

Erin Holohan Haskell

@hot rod - This is fantastic! Thanks for taking such a visual approach to teaching. I'd love to see a video too.

keyote

This makes me wonder about my last post about the lochinvar schematic which shows the air dirt separator on the generously sized header I would think it would be a bad place for it unless you didnt upsize the header < 2 fps untill after the separator

Gordy

Think wide spot in the road if that anology helps. The dirt seperator creates that.

Then think like dirt particles and air bubbles.

Then you must think about where you don't want them, and where you want them to end up to be removed. Be one with the air, water, and dirt. Then no visual animation is needed.

keyote

yeah so a "generously sized header" is a wide spot in the road, and the animation shows dirt slowing to a standstill as velocity falls so i would think you would not want the separator on that wide spot where they show it or have i got it backwards and you want it where the water is slowest.

SWEI

keyote said:

have i got it backwards and you want it where the water is slowest?

Right. Slow the water down: The dirt falls and the bubbles rise.

Gordy

Actually the dirt seperator/air removal device creates its own wide spot in itself. However using the larger dia. Header helps the device do a more proficient job.

SWEI

A bit of semantic scrambling, but we are both really saying the same thing here.

keyote

thanks for clearing that up

hot_rod

No harm in having multiple "wide spots". Include a magnetic band on that spot if you plan on using ECM pumps

Strainers or dirt depressors will not remove fine magnetite particles commonly found in hydronic piping

keyote

those things are really pricey if its really needed ill do it just wondered if people noticed the ecm pumps claim to have it built in and if that putting a magnet in the strainer basket was going to really hepl

Larry Weingarten

Hello: Just a fun little FYI, a Frederick Dye, who passed away in 1930, wrote a book called Hot Water Supply and in it he describes how to use amber or hardwood dust to show the movement of water in glass apparatus he would build to simulate different heating systems. Here is a drawing of his.
Good stuff!

Yours, Larry

DanHolohan

Dye. How appropriate!