> >>> Also, as my figures hopefully showed, you don't need much flow if
> >>> water mixes fully.
> >>>
> >>> 42 watts per (cc per second) at 10C rise.

> >> 10C rise seems rather high to me.

> > That deep-ends on what you think is rising relative to what.

> My understanding was that by "rise" you meant Twh-Twc
> >Ths =A0Cooled heatsink temp
> What do you mean by "cooled heatsink"? do you mean the waterblock or the =
radiator?
> AIUI there are more like seven temperatures involved

I imagine that we agree reasonably well on what was involved and that
a real [tm] fluidynamicist [tm] may even identify 42 relevant
temperatures.

I was aiming at basic concept - hence my use of "weasel words" such as
" ...  if water mixes fully. ..."

and

" ... There are 4  temperatures involved, ASSUMING each is HOMOGENEOUS ..."

eg the radiator ( or whatever (I didn't specify) is used) section was
dumbed down to T water in, T water out and local ambient.
I agree that lots goes on in there that you can play with. That was in
fact my point in noting that water temperature rise across the hot
element was not liable to be the key figure of merit.

Similarly I allowed a homogeneously hot thing cooled by a stream of
well mixed cold stuff. Getting the heat from core to fluid boundary is
a necessary 'exercise for the student'.
My main point there was that using water you can cool  4.2 Watts of
heating if you have a flow of 1cc per second at a 1C averge fluid rise
or 42 Watts for 10C rise. The reason for saying 10C rise was to show
intuitively that you can get quit real Wattages at very low flows by
any normal standards. Saying 100 cc / second to coo, 420 Watts at 1C
rise makes the point less graphically that saying 10cc /second at 10C.
Those who get excited by the subject can then explore.

FWIW air flow needs ~~~~~~=3D  500 to 1000 x the volumes to achieve the
same result. litres per second of air are no great problem (usually)
but it's worth noting).

But, yes, there's more to it than my simplistic summary covers.
But, given the stated assumptions I thing it gives a good feel for
what is needed.


      Russell

..

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