[Stoves] Blower -- Was Re: Tanzania Project

[Paul S. Anderson]

Quoting Stephanie Keller <keller_geo at yahoo.com>:
    (snipped)
> If you have any information relating to durable and 
> simple-to-construct improved cookstove designs, please advise. We are 
> particularly interested in fan stoves due to their high efficiency.
>
Dear Stephanie and all stovers,

As suggested by others, you should STUDY the info at the Stoves 
Internet site. There are many variations.

You have indicated a knowledge of and interest in "fan stoves" (stoves with
forced air).  If you want to seriously consider having the Philips stove, you
will need contact the Philips people directly.  I hope they have 
written to you
Off-List already.  But that stove does not meet your criteria of
"simple-to-construct."

My current work with forced-air stoves is not yet documented on the Internet
site.  I expect to present at or before ETHOS 2008.  You or some 
representative
should consider attending that conference.  Seattle area on last weekend of
January.

My forced-air stoves are TLUD gasifiers.  I believe that the newest 
design that
I am finalizing now in India could be highly appropriate for your needs and
conditions.  I will address here only the issue of the forced air:

1.  Axial fans (like computer muffin fans) are inferior to centrifugal blowers
(squirrel-cage devices) in terms of air flow.  My TLUD requires a true blower.

2.  Blowers are common, but usually rather large for the needs in residential
cookstoves.  So we are building our own in India from esentially basic
materials except for the 12 volt DC motor that is from China and is the type
common for tape recorders, etc.  Rating is 300 milliamps, so very little power
is required.  Motor cost in India is US$2.  (The entire blower but not 
of great
quality from Vietnam that I obtained in Cambodia at US$2 each does not seem to
be available  --  at least I cannot contact the company.)  Our complete blower
system in India should cost only $5 or $7, but still too early to say.  In the
USA it would sell for $25 and still be far better and less expensive than what
I have found in the USA for my experiments there.

3.  Our blower in India has a PWM (pulse width modulator) that will 
give control
of the motor speed WITHOUT the energy losses from using simple 
resistors to slow
down the motor (lower the voltage but waste the unwanted volts as heat).  For
example, 12 volts turned down to only 6 volts means 50% is wasted when using
resistors, but means about double the battery time when using the PWM.  We are
making our own PWM for 500 milliamps here.  I expect to bring a few units back
to the USA.  (I have extended my stay here until 20 December).

4.  Price also relates to the original power source.  My project here has 220
volt AC power to each house all day every day.  So we are using low-amp
converters that here (India) are called "battery eliminators" because they
allow users to power their radios, etc., without batteries.  You do not need
this if you are running the blower from a battery system, such as rechargeable
batteries with solar charging.

5.  The blower blades (squirrel cage) is being made from acrylic sheets 
cut and
glued with a jig.  Estimate is 50 units per day production, but 20 per day
would be plenty for starters.  We expect to go to injected moulded plastic
quite soon, with price of only pennies per unit.

6.  The blower is for use outside the stove device.

So, to answer your un-asked question, yes, everything concerning this blower
system can be transferred to Tanzania or anywhere else.  You can let me 
know of
any interest, but I will not be getting into specifics until January after all
is tried and true.

Happy Diwali!!!    Major festive holiday in India on 9 Nov!!!

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson


----------------------------------------------------------------
This message was sent using Illinois State University Webmail.