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Why aren't there copper radiators?

Discussion in 'Tech' started by E=MC2, Jun 17, 2005.

  1. Crispy476

    Crispy476 Well-Known Member

    Electrolysis is only a problem when two different metals touch like steel and copper with water or a fluid moving through it. That is why in plumbing you can not connect copper to a water heater or other dissimilar metal with out using a dielectric union or brass (it is a natural dielectric). The union is usally brass or copper with a thick plastic washer used to seal the connection while keeping the two metals from touching. This is also used in large buildings where there is a hydronic system for heating and cooling. You will run steel lines (4" and 6") pipe and have smaller (1-2") copper lines going off to different rooms. At every poins a Cu lines comes off the steel there is a brass male adapter. That isthe dielectric. No corrosion.

    This is seen quite often in older housed where the socalled plumbers did not know what they were doing.

    But back to the question. I would say that the reason for Al over Cu is cost.

    Crispy
     
  2. repars

    repars Active Member

    The real reason there aren't copper radiators is because the factor limiting radiators is the heat transfer to the air through convection, not the conduction of heat though the base material copper or aluminum.

    JP
     
  3. E=MC2

    E=MC2 Well-Known Member

    well, it isnt exactly a limiting factor, with an absolute limit. if the radiator was hotter the air would cool it so the temperature would drop more.
     
  4. number41

    number41 Well-Known Member

    $$$$$

    All of the above stated reasons play into the equation also. However, I believe money is the real issue. Aluminum is lighter and performs just as well for most applications, especially when you factor-in the costs associated with mass production using copper. Case-in point: copper is so expensive that pennies aren't even made of it anymore! Since the early seventies, the price of copper has made it necessary to make pennies out of zinc-alloy and coat them with copper. Check me on this. You can scratch the surface layer of copper off of a penny. The U.S. Gov't realized that they were losing a shite-load of money by using solid copper and changed-over.
     
  5. GrahamB

    GrahamB Well-Known Member

    But the return is pretty minimal. Suppose an Al rad runs 2C cooler than the water it contains. So maybe it's at 87C, or perhaps 67C above ambient. (Suzuki thermostats tend to open at 89C).

    Now if copper was twice as efficient a conductor (it's not, I don't think), then the rad would be at 88C, 68C above ambient.

    Newton's law of cooling now tells you the rate of heat transfer from rad to air will indeed be greater, by a factor 68/67, or about 1.6%.

    In general, if the thermal conductivity between rad & air is k% of that between water and rad, only k% of an improvement in water to rad transfer will make it through to overall water to air transfer.

    You could do much better by improving the limiting step, ie make the radiator bigger to improve rad to air transfer. Since Al is lighter than copper, you can build a bigger radiator for the same weight, which will more than compensate for the reduced thermal conductivity of Al relative to Cu.
     
  6. E=MC2

    E=MC2 Well-Known Member

    Re: $$$$$

    instead of scratching i used a 350v capacitator and sparke the crap out of that penny and got zinc spots on it, i also gave abe lincoln zinc nipples:D :Puke: :Puke:
     
  7. RDJeff

    RDJeff Well-Known Member

    Copper isn't nearly as strong, and then there is the old problem of work hardening, where the metal gets very weak over time. That, and copper is more expensive, and getting worse every day!
     
  8. Borg54

    Borg54 Active Member

    Metrakitracer70 - first of all do you own a copper mine or something?

    I agree with most of the answers except i think cost is only a very small part of the equation b/c if copper was indeed better it would be on every MotoGP bike in the paddock.

    I know very little about metals, but what about titanium...same problems?
     
  9. GrahamB

    GrahamB Well-Known Member

    Ti would be worse than Al in every possible way I think.



    Except bling, of course :cool:
     
  10. E=MC2

    E=MC2 Well-Known Member

    and all the radiators would sing you know they call me ti but you dont know me and then everyoen would start kicking their radiators in the face.

    I dont own a copper mine unless you're talking about the name for an intel celeron core known as coppermine my friend used to have that cpu. i said copper just because its more thermally conductive
     

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