[Stoves] Charcoal as space filler in TLUD reactors

[ajheggie at gmail.com]

[Default] On Mon, 6 May 2013 18:48:57 -0600,Ron
<rongretlarson at comcast.net> wrote:

>Martin
>
>      B.  I really like york idea of the aquarium pump, but ask you and others knowledgeable on fans, blowers, pumps what might be the downsides.  Where AC electricity is no problem, and one has such pumps (I have several), can you describe a scheme to both vary the output and measure the air flow quantities?  


Ron, Martin and stovers, 
We have of course talked about, and Philips implemented, a TEG to
provide electricity for air flow. To my mind ' especially given the
various orifices and bluff bodies which act as restrictions and
produce turbulence, if the primary air flow is forced the greater
volume of offgas resulting can entrain its own secondary air. This is
why I have tended to use centrifugal (snail like) fans.

Metering the primary air to keep it constant as the fuel+char bed
resistance changes has been a wish of mine. With a simple hot wire air
mass meter and a feedback loop to change the air supply.

I have recently been shown a TEG just 40mm square with a hot side that
can stand 350C and Cold side 180C and a 140 Watts of heat throughput
that can output a couple of Watts, now this low conversion of heat to
electricity is only 4% but it's a lot better than previous ones I have
seen and the thermal cost is small, unfortunately the capital cost
makes it a toy for the first world.
>
>      A few years ago, Andrew Heggie gave me a small homemade $1 or $2 device to do this.  Anyone found such in local hardware stoves?  Wall dimmer switches?  A single speed device won't tell us enough. 

To be fair this prototype was donated by the maker, Steve Taylor, it's
a brilliant little pulse width modulated voltage control, that means
it is very efficient as it changes speed. It also is good in that it
can operate, and be left set, at a low speed, many motors won't start
at their final low speed but this one starts at high power and then
immediately modulates down to the slow speed without stalling. I don't
think it was quite as cheap as you remember because there was not much
interest from[stoves] at the time Steve could not calculate a market
rate with no known demand.

Suffice it to say I still have the box of bits , less a few crucial
capacitors, to make more but Steve would have to help me out with some
instructions as I am not at all adept with a soldering iron.

AJH