Dear Stovers,
Now that I have finished several months of numerous trips, I hope to
participate more on our Stove Listserv.
It is delightlful to read of the increasing interest in the TLUDs. No
less than Dean is now providing results. Welcome to the world of the
gasifier cookstoves.
As Paal has provided, I request similar details from Dean about the
TLUD(s) that he used. There are too many TLUD designs for us to know
which specific unit you were using to obtain the reported results.
And/or were those results from more than one TLUD design?
Dean Still wrote: (copied from messages below, with my comments added):
Adding more air holes in the bottom of the fuel chamber in a TLUD
allows pellets to burn up completely.
1. Pellets are the fuel? Always pellets? What other fuels are used
in the TLUD tests at Aprovecho?
If users want bio-char they just have to have fewer holes. Then the
char is made since there is not enough air to support burning it.
2. The TLUD can have plenty of holes and still make char if the user
dumps out the char at the end of the pyrolysis stage. OR if there is
an external way to block the incoming primary air after pyrolysis is
finished. Some TLUDs have that ability.
If it is tuned (!), the TLUD is very low in PM when it does not
make smoke when starting and finishing the burn.
The key word is "tuned" (with exclamation point no less). That is the
advantage of having stoves tested repeatedly under the PEMS emissions
measurement equipment. We can look forward to more of that as more
PEMS units are purchased. [Thank you Aprovecho for getting the PEMS
to the market!!] I had the opportunity last month to use the PEMS at
CREEC in Uganda (becoming Africa's focal stove testing location) and I
hope to use it at Zamorano University in Honduras in the coming months.
CO is also generally low. In the well tuned TLUD we generally see
around 7g of CO and 400mg of PM during the WBT compared to a
carefully operated open fire at 55g CO and 2300mg PM.
This comparative data is FANTASTIC!!! Such findings need to be
included in updates of the comparative data found in:
www.bioenergylists.org/andersontludcopm
and in some later versions of that graph where I also added the CO and
PM of charcoal stoves.
That graph is NOT proprietary to me and I would welcome anyone who
would make improvements of display or add more data. (I would like to
remain as a co-author or at least be cited on the newer versions of
the graph, but updating that table is not my priority with my limited
time, so I seriously request others to jump in. If you contact me
off-line, I will be able to supply further assistance.)
Generally the TLUD makes less smoke at the finish with more air
holes because all the wood burns up without making smoke.
Stated differently, at the end of the pyrolysis stage, it is desirable
that the finish be strong (with a goodly amount of primary air) as it
changes over to char-gasification. Otherwise, the last remaining
biomass (not yet char) is in the inside of the charcoal pieces and is
coming out slowly, too slowly to maintain the flame in the secondary
air zone. By having a good transition to the char-gasification stage,
there is no smoke, not even a small puff. Therefore:
do not cut back on the primary air when near the end of the pyrolysis
stage. Instead, (and especially if the holes are few) the user can
even blow gently or fan the primary air a little (manual fanning is
fine, a small fan/blower is also useful but not essential.)
Isn't it great that a TLUD can be operated in both char making and
no char making modes?
Yes!!!! But if the char is to be consumed in the TLUD, there can be
higher temperatures that negatively impact the metal stove materials.
The user can choose whether they want greater fuel efficiency or
to make an agricultural additive.
Actually, the heat of the charcoal burning is rather far down from the
bottom of the pot. In our testing at CREEC in Uganda and later in
Malawi, the hot char can be well used for either ignition of the
second TLUD unit and/or be dumped into an appropriate charcoal burner
upon which the cooking pot could be placed for further cooking or
simmering in close proximity to the bed of charcoal. The latter would
be greater fuel efficiency than leaving the char to be consumed in the
TLUD.
Ahhhh!! TLUD science!! There is still so much TLUD technology to be
learned and implemented into these remarkable stoves. I know of
numerous elements of TLUD progress that have not yet been reported to
the Stoves Listserv or anywhere else.
I encourage all of you to jump into the TLUD efforts.
Paul Anderson "Dr. TLUD" Skype: paultlud
***********************
Quoting Paal wendelbo <[email protected]>:
Grispin
To your infomation if Dean dont' have the exact figures by hand the
TLUD-ND I made at Stove Camp 2009 had the following settings.
The combustion chamber had a diameter 150mm and was 180 h
a.. 55 mm free space from concentration lid up to the pot
b.. 105 mm hole in concentration lid
c.. 6 mm split between concentration lid and top of thee
combustion chamber - 4x15mm for the stand for 2nd air
d.. 5 five mm holes 75 mm up from the bottom on the side of the
combustion chamber
e.. 5 five mm holes 25 mm up from the bottom on the side of the
combustion chamber
f.. 13 five mm holes at the bottom plate for 1st air
g.. 15 mm space between combustion chamber an cover for preheating
of 2nd.air
The combustion chamber was filled with 1kg of wood pellets and a
complete 5 wbt carried out.with following result.
Fuel to Cook 5L
(8 50/1500) g 768.8
CO to Cook 5L (20) 23.0
PM to Cook 5L (1500 223.1
15,000/25,000mkJ
Energy to Cook 5L 14,807
Time to boil 5 litres min 28.1
CO2 to Cook 5L 708.6
Regards Paal W
----- Original Message -----
From: Crispin Pemberton-Pigott
To: 'Discussion of biomass cooking stoves'
Sent: Friday, December 03, 2010 2:40 PM
Subject: Re: [Stoves] K Smith Article in Energy for Sustainable Development
Dear Dean
I really appreciate the info and the flexibility you have built
into the stove. Can you please tell us how much fuel mass was burned
(perhaps in the case of a char consuming version) and the MJ/kg of
the fuel? I wondered what the emissions are per dry kg burned or per
even better, per MJ of heat produced.
My interest is to be able to make comparisons with other fuels and
combustion efficiencies.
Thanks
Crispin
From: [email protected]
[mailto:[email protected]] On Behalf Of Dean
Still
Sent: 03 December 2010 13:31
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] K Smith Article in Energy for Sustainable Development
Hi All,
Adding more air holes in the bottom of the fuel chamber in a TLUD
allows pellets to burn up completely. If users want bio-char they
just have to have fewer holes. Then the char is made since there is
not enough air to support burning it.
If it is tuned (!), the TLUD is very low in PM when it does not
make smoke when starting and finishing the burn. CO is also
generally low. In the well tuned TLUD we generally see around 7g of
CO and 400mg of PM during the WBT compared to a carefully operated
open fire at 55g CO and 2300mg PM. Generally the TLUD makes less
smoke at the finish with more air holes because all the wood burns
up without making smoke.
Isn't it great that a TLUD can be operated in both char making and
no char making modes?
The user can choose whether they want greater fuel efficiency or
to make an agricultural additive.
Best,
Dean
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