cross hatched copper tube for condenser coil

[J.S.]

Hi, this is my first post here. Let me know if I posted this in the wrong section.

Anyway, I'm wondering if anybody can elaborate on why someone would spec cross hatched copper tubing (on inside of tubing) for a condenser coil?

I wondering what benifits, performance-wise the cross hatching has over plain smooth tubing.

If anybody wants to also comment on riffled copper tubing, feel free to. Thanks. I'm curious.

[TRASH101]

Firstly welcome

Secondly you've posted in the right section

The cross hatch tubing is purely serves as an increase to the internal surface area of heat X where the rifled tubing is a little more involved. I believe that in the evaporator the rifling causes the liquid to swirl fast enough to cause a centrifugal effect where the liquid is forced to the tubing walls while the vapor formed from evaporation is carried centrally in the vortex resulting in better rates of evaporation as the liquid contact to the transfer surfaces optimal. On the downside the velocities that can result may case oiling of the liquid which decreases the transfer rate.

[J.S.]

Firstly welcome

Secondly you've posted in the right section

The cross hatch tubing is purely serves as an increase to the internal surface area of heat X where the rifled tubing is a little more involved. I believe that in the evaporator the rifling causes the liquid to swirl fast enough to cause a centrifugal effect where the liquid is forced to the tubing walls while the vapor formed from evaporation is carried centrally in the vortex resulting in better rates of evaporation as the liquid contact to the transfer surfaces optimal. On the downside the velocities that can result may case oiling of the liquid which decreases the transfer rate.

Thank you for welcoming me and also for the insight!

Specifically about the cross hatched tubing interior for a condenser coil, it's for more surface area. Sounds logical.

The theory of the rifled evap coil tubing is definately interesting.

In my limited experience, I've only seen rifled tubing on a condenser coil. I could be wrong but I don't think the theory mentioned for rifled tubing on an evap coil applies to a condenser coil since they operate differently (I know you're aware, I'm just saying that out loud). On a condenser coil, would rifled tubing be simply to increase surface area like cross hatching? If that's the case, I'm guessing cross hatching would be a more extreme case of surface area increase, whereas rifled tubing would be less extreme?

I still have a lot of learning to do, but I'm just trying to get a grip on tubing interior wall surface differences at the moment. Thank you.

[TRASH101]

The rifled tubing works well with evaporators and to a lesser extent condensers.(you'll notice in my previous post my carefully chosen words)

I have found a link to some limited info

http://www.achrnews.com/Articles/Fea...100000f932a8c0____

If your lucky some of the boys that work on NH3 will see this thread and direct you to a more involved and definative answer than I can.

good luck

[J.S.]

The rifled tubing works well with evaporators and to a lesser extent condensers.(you'll notice in my previous post my carefully chosen words)

"The cross hatch tubing is purely serves as an increase to the internal surface area of heat X where the rifled tubing is a little more involved."

Aah yes, thank you. And for the link!

[amitsaxena]

Dear J.S,

There are two benefit of using the hatched tubes

1. Increase in surface area
2. Increase in Heat transfer coefficient as it wont allow the flow to form boundry layers and also produce turbulence hence better Nu number and Heat transfer coefficent.

Thanks
Amit Saxena