[Stoves] New type of electricity generator suiteable for stoves - early development stage.

[Kevin Chisholm]

Dear Crispin

They are targeting to reach 85% of Carnot Efficiency. Carnot Efficiency 
is (T2-T1)/T2.

If the effective tempeature attainable from the computer was 150 F, 
(460+150 =610 Rankine), and the Office Temperature was 60 F, (520R), 
then 100% Carnot efficiency would be (610-520)/610 = 90/610 = 14.75% , 
85% of which equals 12.5%

85% efficiency might be attainable with high temperature applications, 
but it would be virtually impossible in low temperature applications. 
The difference in "cold end temperature" and the ambient temperature 
would probably be in teh range of 20 F, to keep heat exchanger size 
reasonably small. That one factor alone would reduce the maximum Carnot 
Efficiency to 70/610 = 11.5%.... that alone limits maximum efficiency to 
11.5/14.75 = 77.9% of Carnot.

It looks like the Writer who put together the story traded off a bit of 
perspective and fact for enthusiasm.

Kevin

Crispin Pemberton-Pigott wrote:
> Dear Peter
>
> While not fronting for the guy, a laptop that produces heat and which can
> recover perhaps 20% of it - not too bad.  Steam generators have been using
> waste heat for running equipment and heating buildings.  I don't see it as a
> major claim.
>
> Did he say that the laptop was going to literally power itself with its own
> heat? That would be stupid.
>
> Hey, someone good at math: How long can a laptop run on a 4 hour battery's
> worth of energy if 25% of the energy can be recaptured heat-generated
> electricity on a continuous basis?
>
> Is it as simple as 1.25 x 4 hrs = 5 hrs?
>
> A free hour?
>
> Not too shabby...
>
> Regards
> Crispin
>
>
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