[Stoves] Re Alexis Belonio article

[Dean Still]

Dear All,

The Chinese stoves usually use a small steam box which is filled with hot
water (the Chinese frequently have hot water around for making tea in a
thermos bottle) but it takes about 10-15 minutes for the water to boil so
the jets do not happen right away. I tried making a Rocket stove with a
water jacket surrounding the combustion chamber but still had to wait 10
minutes for steam. So, in a stove that boils quickly anyway it would be nice
if the steam jets were active sooner.

One of the advantages of the water jacket would be that metal in the
combustion chamber would stay cool. So longer life.

I have been having trouble with the steam wetting the combustion chamber so
maybe I'll try a condensing plate between the reservoir and the holes to
reduce spitting.

Mark Bryden has written that doubling the velocity of hot flue gases flowing
near the pot would approximately double heat transfer by thinning the
boundary layer of still air under the pot. So I am trying to boost velocity
whether using air or steam jets while keeping temperatures high.

Best,

Dean

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of David G. LeVine
Sent: Saturday, April 07, 2007 8:27 PM
To: Crispin Pemberton-Pigott; Discussion of biomass cooking stoves
Subject: Re: [Stoves] Re Alexis Belonio article


>The interesting difference between the loco and the stove is that we
>primarily want the air for mixing rather than for increasing the combustion
>rate, that is, for creating a well mixed burn instead of higher power from
a
>limited physical size.  That leads me to believe (so far) that it is
>possible have an increase in overall efficiency because of the small amount
>of power required to stir things up.

What I saw the steam as was a replacement for an electric fan.  Most 
TLUD units use a fan to get the flow high enough for maximum heat 
out.  Steam meant no electricity needed.

>It may be that people are injecting steam without regard to checking 
>the emissions or the efficiency.

That is quite possible.  Would you (as a person struggling to 
survive) trade off a few extra twigs for another 15 minutes to gather 
food?  I would bet you would rather than not having enough calories 
to stay alive.  If someone gave me a super-hot stove which took an 
extra few twigs, but heated the water in 1/2 the time under those 
conditions, I would, and I wouldn't care about pollution one bit.

In a survival situation the extra time has to be traded off against 
the extra fuel.  A 12 foot high pile of rice husks won't feed me, but 
an extra 300 calories might let me survive an extra day.


David G. LeVine
Nashua, NH  03060


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