aluminum heat exchanger

[Lc_shi]

hi sirs

Is it feasible to apply aluminum tube for evaporative condenser if it's with good anti-corrosion?
It's cheaper than copper and lighter than steel.

what's your comment?

thx!

rgds
LC

[desA]

hi sirs

Is it feasible to apply aluminum tube for evaporative condenser if it's with good anti-corrosion?
It's cheaper than copper and lighter than steel.



What is an 'evaporative condenser'?

:confused:

[chemi-cool]

Aluminium will have to be coated against corrosion.

[Sridhar1312]

Aluminum as such is not protected from corrossion as we seen complete fins got powdered with three months of installation at Salallah in Oman.
Thus if it aluminum alloy with corrosion protection should be suitable.

[desA]

Aluminum as such is not protected from corrossion as we seen complete fins got powdered with three months of installation at Salallah in Oman.

If aluminium is used correctly, the aluminium oxide layer is generally sufficient to protect the fin material. The corrosion mechanism here is the speed with which the fin forms its protective oxide layer.

What messes things up is if the aluminium is sacrificial with respect to some other material e.g. copper - or even aluminium-alloy, in the presence of water. This forms a galvanic corrosion cell.

The way to assist here could be suitable fin protection (coating), suitable resistant alloy, or even correct electrical earth-straps - some form of disrupting the electrical galvanic cell.

My main concern is aluminium-copper systems in the presence of stray current & water, which would accelerate the corrosion cell.

Aluminium-aluminium fin-tube systems can be made to last for reasonable lifetimes under fairly extreme operating conditions. Look at the condenser & radiator in most modern automobiles.

[wilsoncheung]

Very good! desA.
I have studied the corrosin mechannism of the aluminium and the aluminium-copper heat exchanger. I found that aluminium will corroded if it was with copper by the mechanism of electrical galvanic corrosion.

[desA]

^ Thank you. It is my pleasure.

If you need further information in this field, please ask - I'll try to point you in the right direction.

[Lc_shi]

Hi desA

Your comment is valuable. I plan to try to build a AL coil as an evaporative condenser. There're two issues need be considered:
#1 : the water is sprayed on the AL coil ,how about the corrosion ?

#2: need to weld aluminum with copper tube of the compressor. how about the electriacl corrosion between copper and al

[desA]

#1 : the water is sprayed on the AL coil ,how about the corrosion ?

What materials eg. 3003, 6000x series etc, are you using for the fins, tubes? You will need to investigate their galvanic potential values - by test - AFTER brazing. If mechanically-joined, then the as-supplied galvanic potentials.



#2: need to weld aluminum with copper tube of the compressor. how about the electriacl corrosion between copper and al

Use an aluminium tube clad with copper. This is now common in Asia.

If galvanic corrosion of the pipe/compressor joint becomes a problem, then perhaps look into an electrical strap across the pipe/compressor joints, to remove charge build-up.

There are electrical devices which can also disrupt a galvanic corrosion cell. Be careful of stray electrical currents.