[Beowulf] oil immersion cooled blades
prentice at ias.edu
Fri Mar 16 08:08:16 PDT 2012
On 03/16/2012 12:47 AM, Nathan Moore wrote:
> If you take a cm^3 of space, right next to the cpu and fill it either
> with air, or with oil, you'll have many, many, more atomic/molecular
> degrees of freedom to fill with energy in the cm^3 of oil. Getting
> that energy out of the cooling medium seems primarily like a
> fluid-flow problem - given oil's higher heat capacity, you can leave
> it around something hot, and still have it serve as an effective heat
> sink for a longer period of time than you can with air. My point is,
> the fan for the air has to run much faster than the oil pump for the
> oil coolant.
> I'm too young for this, but didn't VW and Porche cool some of their
> engines with oil through the early 1980's?
Yes, I and was going to mention that in the e-mail. I just posted. The
original VW "boxer" engines were air cooled. If you look at the
cylinders, they have heat fins on them like a CPU heat sink or a
motorcycle engine to promote heat transfer to the air. For VW fanatics
(of which I used to be one) there two types of VWs: air-cooled, and
everything else. I was in the "everything else" camping, owning several
rabbits and GTis.
The engines in the early Porsches and the 911s trace their lineage all
the way back to the first VW beetle engines, and were also air-cooled
boxer engines (boxer = horizontally-opposed cylinders). Porsche 911s
retained air-cooled engines well into the 1990s, and went to
water-cooled engines because it was getting too hard to meet tougher and
tougher noise and emissions requirements with air-cooled engines. As a
bonus, I think liquid-cooling really helped increase how much horse
power they could put out, too. But you lose out on the very distinctive
sound that the air-cooled 911 had. :(
Do you remember the 911 turbos with that big "whale tale" rear wing"
That wing wasn't really there for aerodynamics (although it did help for
that, too) It was there to house the massive air-to-air intercoolers
needed to cool the turbocharged air. Since they went to liquid cooled
engines, you really don't see that any more.
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