powering the third world - Page 3

 

On 23 Jan 2006 07:53:21 -0800, meow2222@care2.com wrote:


Nick, I liked your idea of towing a ship to some un powered remote
country and allowing it to turn to ferric chloride ( a source of iron
to increase photosynthesis from the sea) whilst it provided
electricity. I wondered how the electrical output compared with the
thermal input of the original smelter. My (employed) work generates
about 3kg/day of worn ground engaging steel parts, as it takes too
long to collect a decent load for the scrap man and if I lived on the
coast I would gladly reduce it to ferric chloride and derive power
from it.

Now I did some figures for a cheap thermopile, to power a fan for a
small 3rd world cook stove. I figured it needed to be something the
local blacksmith could make from scrap material, I plumped for nickel
iron junctions and the device to form the bottom of a cook pot, as the
whole heat flux has to pass through the junctions and is ~1%
conversion to electricity. If it is the bottom of a pot then at least
the cold side goes on to boil some water.

Material    Seebeck  Coeff. *
Iron        19 micro Volts/deg C @ 0C
Nickel     -15

Assuming this is somewhere near linear in the range 0 to 400C:

So if the water in the pot is the cold sink and boiling and we have a
flame of 800C but the boundary layer halves what the thermo couples
see then we have a delta t of 300C to play with. If my interpretation
is correct we should have 34micro Volts times 300 output per junction,
we are looking for 1.25V , suggesting 123 couples or 246 junctions,
fiddly.

AJH

 

AJH wrote:

Battery power comes from corrosion of the metal, so the ship in water
wouldnt last well. Its financially inefficient method, unless you have
a source of metal that you cant get anything for. For you it might run.



Why do you need 1.25v though? 0.1v could be transformed into whatever
V_out you like using a transformer and vibrator. When youre dealing
with 0.1v max, water is more or less an insulator.

Heat powered thermopile gens have been made, the famous example being
the russian 12v paraffin generator. A bit less well known is a pakistan
designed candle driven wire thermopile. A bigger solar version of that
was what I had in mind.


NT

 

 meow2222@care2.com wrote:


Just a note here....I own a Global ThermoElectric Propane fired Generator
that does 240Watts output, using aprox. 1 USG/Day.  It isn't especially
efficent for power production, but in a cogen situation, it has its
advantages.  I use the Cold Air side of the pile to heat the WellHouse
that has my 500USG Domestic Water Tank in a Highlky Insulated room.
The power provided, is used to keep a 1200Amphour bank of L16's
charged.  Up here in the Frozen North, having running water in the winter
does tend to keep the womenfolk happier, and the extra power is nice
in the PowerBalance for the Inverters.

Bruce in alaska
--
add a <2> before @

 

On 27 Jan 2006 13:33:15 -0800, meow2222@care2.com wrote:


I understand this, I was looking on it as idle conjecture in the
absence of figures that showed the electrical output compared with the
thermal cost of reducing the ore.


I was considering making use of existing battery powered fans, I've
not seen any practical examples of a vibrating reed switch stepping up
voltage through a transformer.

Bruce has posted that he uses such a device, on the surface the
figures he posted suggested a conversion efficiency in the teens. I
have yet to see a practical model using metal-metal junctions and
making use of the waste heat. I am aware of several commercially
available semi conductor ones.

I have similarly see stirling powered fans for mounting on a stove top
to distribute the heat which make more sense.

My quest was for a simple device to be used in conjunction with a cook
stove to both increase its efficacy and maybe generate enough surplus
for charging a small battery for IT use. I had concluded the
thermopile using metal to metal junctions was too difficult, I wish to
be proved wrong.

AJH

 

AJH wrote:

Lets give it a go.



ISTR doing some quick calcs on the possibility of using scrap to
generate power, and although the material quantities made sense if
youve got scrap to get rid of, there is labour involved in running the
thing. Its certainly very simple to try it though, all you need to get
going is some basic salt cells and a 12v invertor. Salt cells just need
buckets, salt and charcoal.



This was the standard way to run valves on batteries in the 30s and
40s. Google phrases like 'battery eliminator' or 'vibrator power pack'
or 'car radio vibrator supply.' There are of course other ways to do
it, such as a motorised switch, but the vibrator is probably one of the
best techs for such low Vs.



I think he was talking about commercial semiconductor thermopiles,
which are a somewhat diffrent animal. Commericial units youre talking
3%, homebrews more like 1%. Although very low, 10 watts for a 1m device
costing 10p isnt bad, and does have its uses.

They also can produce power after dark with a solar heat store, so have
the potential to be used without battery packs.


NT