Optimize Flow through Counterflow Chiller

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butterblum

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I am converting my old gravity-fed CFC to be used with a pump and a whirlpool arm.
I plan on using the SpinCycle whirlpool arm, which requires a 1/2" NPT male connection.
I plan on just using camlock fittings, and I will use 1/2" ID silicon tubing on the input end of my chiller, but I have questions about optimizing my whirlpool action.
I worry about using 1/2" ID tubing at the output of my chiller, because there will be a flow velocity loss going from 1/4" ID copper tubing to 1/2" ID tubing. I am assuming flow velocity is the most important factor for creating a strong whirlpool.
Would it be better to go smaller and use 3/8" ID tubing between the CFC output and the whirlpool arm? I also don't like having to step up to 1/2" NPT fittings for 1/4" ID and 3/8" ID connections.
 

Smellyglove

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I believe as long as the WP arm is "small enough" that's the piece of equipment which will dictate the pressure you'll get. Don't think the pieces before it will give you less pressure. Even if the pressure varies at different places in your entire loop, it's the output pressure which matters.

I think. I'm no pressure-scientist.
 
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butterblum

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I believe as long as the WP arm is "small enough" that's the piece of equipment which will dictate the pressure you'll get. Don't think the pieces before it will give you less pressure. Even if the pressure varies at different places in your entire loop, it's the output pressure which matters.

I think. I'm no pressure-scientist.
Ironically enough, I am a mechanical engineer....
Skipping my fluids class certainly didn't help my grasp of flow fundamentals.
 

Smellyglove

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Ironically enough, I am a mechanical engineer....
Skipping my fluids class certainly didn't help my grasp of flow fundamentals.

Hehe. And I'm a soundguy. I can relate to a bandpass subwoofer. Where the element itself plays into a cabinet, but the cabinet has a narrow port as the exit thus creating a higher pressure (volume) at the output of the port. The element exhibits a pressure within the cabinet, and all that pressured air wants to escape through that small port. A given amount of air wants to get out of the cabinet, but since the port is smaller, the pressure rises.
 
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butterblum

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Hehe. And I'm a soundguy. I can relate to a bandpass subwoofer. Where the element itself plays into a cabinet, but the cabinet has a narrow port as the exit thus creating a higher pressure (volume) at the output of the port. The element exhibits a pressure within the cabinet, and all that pressured air wants to escape through that small port. A given amount of air wants to get out of the cabinet, but since the port is smaller, the pressure rises.

My worry is that when you step up ID size, there will be a loss of pressure that can't be regained, even by stepping down ID size again.
 

beermanpete

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What you need for the whirlpool action is velocity at the exit of the whirlpool arm. To get velocity a restiction to flow is required. As long as the restriction is at the exit of the whirlpool arm it should be fine. What happens ahead of this point does matter too much as long as the total pressure drop is not too high.
 

wilserbrewer

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The larger tubing will have fewer losses and provide more flow and pressure exiting the whirlpool arm.

Imagine if the tubing ahead of the whirlpool arm was very small, flow would be reduced.

In this instance the difference is likely minimal, but larger tubing provides more flow and less pressure losses.
 

IslandLizard

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The 1/4" copper chiller tubing may be too restrictive, reducing flow, thus pressure and velocity on the outlet of the whirlpool arm.
Why don't you try it out with water and see if you get a strong enough whirlpool? If not, use a T-valve to bypass the coil when you've arrived at your WP temp.

I run my whirlpool through a 30 plate wort chiller, and it works fine on a March pump.
Hops are bagged until I find a better solution for them.
 
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butterblum

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The 1/4" copper chiller tubing may be too restrictive, reducing flow, thus pressure and velocity on the outlet of the whirlpool arm.
Why don't you try it out with water and see if you get a strong enough whirlpool? If not, use a T-valve to bypass the coil when you've arrived at your WP temp.

I run my whirlpool through a 30 plate wort chiller, and it works fine on a March pump.
Hops are bagged until I find a better solution for them.

Yeah, I'm going to just try it out with water first. I probably won't include a T-valve until I have a permanent location for my setup - I will just disconnect the tube from the chiller and connect it to the whirlpool arm.
 

Smellyglove

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Doh! Sorry for stupid reply. I didnt think bakwards past the 1/2 tubing to the chiller ID.
 

JadeAug

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I am also a mechanical engineer, with an emphasis in thermal fluids so I think I can help you out here.

I am converting my old gravity-fed CFC to be used with a pump and a whirlpool arm.
I plan on using the SpinCycle whirlpool arm, which requires a 1/2" NPT male connection.
I plan on just using camlock fittings, and I will use 1/2" ID silicon tubing on the input end of my chiller, but I have questions about optimizing my whirlpool action.
This is my currently my exact setup and I highly recommend it.
I worry about using 1/2" ID tubing at the output of my chiller, because there will be a flow velocity loss going from 1/4" ID copper tubing to 1/2" ID tubing. I am assuming flow velocity is the most important factor for creating a strong whirlpool.
The momentum (mass flow rate X exit velocity) and direction of the fluid exiting the whirlpool arm and flowing in to the kettle is the most important factor for creating a strong whirlpool. You want to achieve as high of a velocity as possible at without restricting the flowrate too much. It is actually better to have the velocity of the fluid in the piping system to be low and the velocity should be increased at the exit only.


Would it be better to go smaller and use 3/8" ID tubing between the CFC output and the whirlpool arm? I also don't like having to step up to 1/2" NPT fittings for 1/4" ID and 3/8" ID connections.

No. Flow restrictions through your piping system come in the form of major head losses (friction from pipe walls) and minor head losses (inertial changes fittings). Using larger diameter pipes and fittings will reduce all losses. You should step up to 1/2" tubing immediately exiting the chiller. I also recommend using the Brewhardware cam lock fittings with the 5/8" barbs as they fit in 1/2" tubing just fine and can be clamped on using only a zip tie.
 
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