Dear Martin and all,
Thank you for your clear explanation. I realize now that I have seen
rotameters before. Dr. Tom Reed uses them, and also Dale Andreatta and
others, but I did not know the name.
I have been "on a different page." The rotometer functions with a
completely "closed" source of air. I have been thinking about the
"open" situations of a TLUD with a fan blowing at it, which is a vastly
different situation.
The desired measurement of air flows needs scientific / laboratory
conditions, which do not have. And a budget for such work to be done
with sufficient repetitions and with different fuels in order to give
the desired results. I hope that CSU can consider this in its
DOE-funded studies. Maybe Morgan or others could let us know if this
type of measurements have been done or are being planned for study.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 5/7/2013 4:31 PM, Boll, Martin Dr. wrote:
Paul,
first of all, have a look to a picture of a rotameter. So it is easier to
explain:
http://www.electro-mation.de/schwebekoerperdurchflussmesser.html
If you use a rotameter, you cannot use a fan to admit the forced air. You must
have somehow really compressed air. The pressure must be much higher than the
fracture of one mm H20 in a stove. The air is (variable) restricted very much
before the air-column of the rotameter , so that through the measure-part of
the rotameter flows nothing (when closed) or e.g. 100ml of air or 2 liters or
4 liters; as you turn more on or off these restriction. The rotameter column
only shows you, (by a floating weight on the air- or fluid-column) how much air
or gas or water flows per minute.
In low tech, you could use a screw-clamp, which quenches an elastic tube.
By doing this, the resistance of the burning-chamber is so small, that it
nearly does not alter the pressured air-flow per minute.
This system with rotameters was used in anesthesia-equipment, to have a
continuos ( and/but changeable !) rate of fresh oxygen, N2O or air coming into
the circular breathing system.
This circular-system has always different pressures during artificial breathing
-(by inspiration pressure plus; by exspiration pressure zero).
Normally between 0cm H2O and 20cm H2O- column. It can exceed up to: say 49 cm
H2O without altering remarkable the incoming amount per time of fresh oxygen or
air or N2O.
When you see these pressure-numbers, it is clear, that it would work in stoves
as well, because the pressures are remarkable lower. I think if you could use
pressurized air, a pressure with minimum 1 meter water-column (0,1 bar)
could work. You could get an air-stream, which is _relatively_ not dependent
from different resistance within the fuel-stack.
If you would take an inflated inner car-tire (the bigger the tire the better ),
good inflated, you had enough air with high pressure to feed a TLUD with
primary air for a long time, without lowering the tire-pressure too much,
giving a (nearly) constant air-flow. The flow-rate would be regulated by a
screw-clamp, squeezing a flexible hose. - Behind that clamp you would have the
a rotameter-column. But you can do without a rotameter:
Bubble through that hose the air into water and fill a dumped, water-filled
glass with these bubbles, to measure the amount of air. Count the amount per
minute and regulate the bubbling to your wish/need. In this setting, you know
the primary-air you get out of that hose sufficient exact. Naturally you must
separate primary- and secondary-air. You could force the secondary air by a
normal fan, if you want to have artificial draft. Primary- and secondary-air
would be to regulate each practically independent from the other.
The most important is, that you know the amount of primary air, and so you know
the primary-air per square-section.
-And that is the point you want to change in the system, because different primary air
gives the different amount of produced "smoke"-
You can adjust the TLUD-burn as you want, to look for its best performance.
-And you get to know the numbers when it best performs.
Mind: measuring the primary air-pressure does not give you the
air-amount-numbers you want (or better you must have ) to know. You must know
the flow number according to the square-section and look to the performance. So
you get to know the right amount.
At the end rises the simple question: How many liters primary-air per minute per square-section needs a TLUD for excellent burning?
Regards
Martin
Am 07.05.2013 um 17:18 schrieb Paul Anderson <[email protected]>:
Martin,
Where would you place the rotometer? Most fans / blowers create back-pressure
(and back flows) that do not go to the fuel stack?
I do not have experience with nor possession of a rotometer. For this I also
need guidance. It would be nice to include this in the experiments at
Aprovecho Stove Camp this summer. And there we can also do experiments with
different layers of fuels.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 5/7/2013 2:22 AM, Boll, Martin Dr. wrote:
Paul,
I do not expect to get much energy, but the performance would be interesting.
Even if there is different rate of mixture in different layers of the TLUD, you
could get different outputs, and do that in mind the needs of the
cooking-proceedure.
Upper layer charcoal, to get ignition without smoke, than fuel with few
charcoal as space-filler, than charcoal with (one have to experiment the rate
of fuel/charcoal) fuel-bits, possibly a sort of raw saw-dust. And at the bottom
just some charcoal to finish without smoke.
If you allow only the amount air liters per minute to pass the rotameter and
so the TLUD-primary (naturally you have to separate primary from secondary.air)
you know exactly the rate of air. You have to calculate the free space in order
to get the real air-speed in this area.
I think even if that is naturally not the true surface-speed on the fuel, it is
a good number to deal with.
Even if you don't have the right number, you could calculate from one
good-working TLUD to another which has a different Square-flat.
Mind: The high of the fuel stack does not count, because the flow-rate is
limited by the rotameter and not by the fuel-stack, because you work with a
relatively high pressure and the flow is limited by the high resistance
regulated by the rotameter.
Little bit in hurry-.
Regards
Martin
Am 07.05.2013 um 04:35 schrieb Paul Anderson <[email protected]>:
Martin,
Concerning "space fillers", I and probably others have put wood chips and small
pieces into TLUDs where there is otherwise too much space between the main biomass fuel
pieces. Yes, the chips do pyrolyze.
But my point is that making small pieces of biomass for filler can be
difficult. But using char pieces from previous TLUD batches is very easy.
But just do not expect to get much energy from the charcoal filler, because it
has already been pyrolyzed.
Concerning your comment/question about measuring the flow of primary air, it is
not sufficient to measure characteristics of the fan/blower/pump because the
holes in the bottom of the TLUD are intentionally small and the fuel is
intended to (expected to) block some of the flow. What is needed is to
measure the flow INSIDE the fuel cylinder, such as in the bottom 2 cm of fuel.
But how to do that?
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 5/6/2013 3:56 PM, Boll, Martin Dr. wrote:
TLUD-ers turn it as you want;
Charcoal as space-filler means __somehow__ that "mixed fuel" is used in a TLUD. From
that aspect it is a "hybrid-fuelled" TLUD.
Change the ratio of the "hybrid-fuelled" TLUD to: wood-pieces as space-filler
(by charcoal-packing). Run this different mixture and look.
Who did this already? Interesting to hear about.
- It would be as well interesting to know the difference in performance between
test-runs with natural draft and with forced air.
Even by that different ratio, the burn can be stopped after outgassing, to get
as final result charcoal.
- Hybrid-fuelled TLUDs would get probably a better quality of resulting
charcoal ( Frank, mentioned that as important difference for bio-char)
P.S. We could stop guessing about the amount of more or less _primary air_
(caused by the minimal pressure of a fan or natural draft in different-dense
TLUD-packages), and make an exact air-dosage by a rotameter, or less expansive
and simpler by an aquarium-air-pump.
Martin
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