[Stoves] Top lit updraft combustors

[Norbert Senf]

On Sat, Dec 16, 2017 at 10:12 PM, Ronal W. Larson <rongretlarson at comcast.net
> wrote:

> Norbert  cc Biochar list, Andrew, MHA (Masonry Heating Association) list,
> and Terrence and Steven
>
> 1. Hello to MHA and Terrence and Steven - who I see are in Ontario
> Government departments.  Feel free to jump in.
>
> 2,  I am particularly thinking of folks in Ontario modifying MHA systems
> so they produce char (mostly to go in the soil).  I believe MH users could
> find that fuel costs could become negative.  (This idea thanks to Andrew)
> The fuel piles will have to be larger or re-fired more often - but these
> char-makers seem to be cleaner.
> I think it pretty unlikely to get through US departments as rapidly as
> OMAFRA and OMOECC, where Government official seem to believe there is
> global warming.
>
> See few comments below - and thanks for yours.
>
> (snip)
>


> *[RWLC:   I think we are a long way from having acceptance of a “ software
> simulator”.*
> * I would have guess that most of your MH units are “one-off”.  They can’t
> be tested in the field at low enough cost?*
>

In the masonry heater industry we have a precedent from Austria. They have
a proprietary calculator, that is accepted for certifying one-off heaters.
The main nuts and bolts behind the math is the European EN-13384 chimney
calculation standard. You basically calculate the friction (pressure)
losses for "worst case scenario" which is with a half load, in the summer,
and verify that the appliance will draft properly. Damien Lehmann in France
has developed an open source version and we are trying to extend it to
include additional heater types than only the Austrian style. Austrian
heaters are "channeled", where the pressure loss calculation is based on
the channel cross sections and length. In North America we have started
building for example, a Russian system that is based on buoyancy and has
significantly less friction and that the Austrian calculator can't handle.


> *  How much change in “fuel analysis” during a batch burn**?  Hadn’t
> heard of this.  but found several papers related toMHA, such as*
> http://mha-net.org/docs/temp/2017-10-16%20Pemberton-Pigott%
> 20-%20Decombustion%20Theory.pdf.
> * Mt tentative conclusion is that this is un-needed for TLUDs, but i am
> surprised at the assumptions needed.  I look forward to understanding this
> and why measurements aren’t enough.*
>

After seeing Crispin's presentation on this at the Stove Design Challenge
event in 2014 at Brookhaven Lab in NY, a team from the University of
Buffalo did some work with it on a cordwood boiler. They found that with a
batch burn of standardized briquettes and a constant fuel composition
assumption "...H2O is underpredicted at early times and overpredicted
during the charcoal oxidation stage, resulting in a mean error of
approximately 64%". The good news is that the two sort of cancel each other
out. I think the error in calculating overall efficiency was somewhere in
the 3% range.

For our calculator effort, we need an accurate flue mass flow rate and
therefore need to measure H2O. Therefore, Crispin's approach should tie in
well with this.

*[RWLE:  I googled for Testo 330-2 and “inexpensive NDIR benches” (on
behalf of Andrew’s emphasis on this) and tentatively concluded we can’t yet
get equipment CO and particulates in the range of $100.  (NDIR =
Non-dispersive infra-red)*

Yes, that would be a stretch. A Testo is in the $2500 range. There is an
interesting NDIR bench on ebay for $26.00:
https://www.ebay.com/itm/NDIR-Infrared-Carbon-Dioxide-CO2-Sensor-Module-MH-Z14A-Serial-Port-0-5000ppm/282697897512?epid=14007377319&hash=item41d21b9628:g:cZ4AAOSwjodZ5eRL

but it only goes to 5000 ppm, likely for HVAC room occupancy measurements.
In principle, you would only need to shorten the chamber in order to get a
higher range. At least that is what I have seen on some older Horiba
benches.


CO is interesting to watch, but we don't care that much about it. It is not
regulated in North America, and is not a health issue except in dense urban
areas. When we tested the Austrian eco-labelled air system, PM dropped
about 50% and CO dropped about 80%. We were a lot more excited about the PM
drop, because this is the number that matters here to regulators. Europeans
have told us that the United States is about 10 years ahead of Europe in
air quality regulation. Largely due to California, in particular Los
Angeles. The Europeans are only just now recognizing the PM problem in
urban areas from diesel and wood burning, and addressing this in their
regulations.



*[RWLF:   Good.  Maybe that helps the garage testing of TLUDs a bit.  If
you ever hear of something in the $100 range,  I believe a lot of people on
this list would be willing to add PM to what they are already able to do
 quite cheaply to get weight,  temperatures, and times for energy
efficiency computations.*
Before my Testo arrived, I was able to do some useful stuff by measuring
opacity. $1.00 CdS sensor, light source, ohm-meter:
www.mha-net.org/graphics2/17121701.JPG

It shows you where in your cycle the PM is, but is hard to correlate with
the "EPA number"

-- 
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com
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