[Stoves] Stirling to drive fan

[AJH]

On Sun, 24 Sep 2006 11:32:34 GMT, steve wrote:

>A type T junction (copper/copper-nickel) (roughly 40 uV/C),
>running at 400 C Delta T, to give a total of 600mV output, I
>make that 600mV=40uV/C X 400 C X N Gives N = 0.6/40E-6/400 =
>40 -ish junctions. Or have I messed up ?

No it's a similar calculation to mine except I was aiming for 1.25V
and my couple was nickel-iron with only 34 microV/Deg C

Cromel-Alumel seems to be about 80 micro V/Deg C

Also I figured this figure was for a couple, i.e both a hot an a cold
junction to I thought it meant double the number of junctions.

I had also allowed for the fact that the hot junction would not reach
anywhere near the flue gas temperature, so I halved my delta T to
allow for this. I suspect the experiment will be necessary to see what
is doable.
>
>Constantan sheet, 1mm thick, 350 GBP 300mm x 1000mm !

This doesn't surprise me and is the reason I plumped for more common
materials. As I said at the time we really need a physics graduate to
run a few calculations because we also need a better feel for the
width of the components of the junction and their thermal conductivity
to establish the thickness of the heat path and hence the required
heat flux.


AJH