[Stoves] Top lit updraft combustors

Sat Dec 16 21:12:10 CST 2017

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.

> On Dec 16, 2017, at 6:22 AM, Norbert Senf <norbert.senf at gmail.com> wrote:
> 
> 
> 
> On Fri, Dec 15, 2017 at 7:08 PM, Ronal W. Larson <rongretlarson at comcast.net <mailto:rongretlarson at comcast.net>> wrote:
> (snip)
> 	2.  But re my on-going dialog with Xavier (hugely longer today) on this same topic,  I need to point out that Norbert said:  “When you get into the weeds of “what is the repeatability of your laboratory method”, the answer is “we don’t know”, and the next best answer is “plus or minus 40%, based on limited data”.
> 
> 	For the WBT under discussion for stoves, I think we are probably about +/- 5% (example:   such as Tier 4 re cooking efficiency at 40% +/- 2%).  I’m happy enough with 5% repeatability and see in the standard deviations numbers much smaller at any single laboratory.  I gather Xavier thinks that is not good enough, but I still have to read through his many articles provided today to understand his concerns.
> 
> Hi Ronal:
> 
> Just to be clear, I was referring only to repeatability on PM measurements. In testing that we did on masonry heater with standardized fuel cribs, we managed to get +/-10% (coefficient of variation), which is the best I have seen except for pellet stoves. However our repeatability on efficiency during the same tests was +/- 0.26%.
> http://heatkit.com/html/lopez2a.htm <http://heatkit.com/html/lopez2a.htm>
> This is "same lab same operator". Much harder to do "different lab, different operator", as you are required to do (theoretically) for EPA round-robin proficiency testing.
> 
> (snip)
> 	[RWL3:  Norbert - my interest in this topic is from the perspective of char-making stoves (both cooking for this list and heating from yours).  In your world, would the practitioners accept the idea that your “kilogram of fuel” be modified by subtracting out the fuel that went into char?   (I’m simplifying here, because char has higher energy density).  I’d appreciate anything more you could add on “harmonizing” with char in mind. 
>                  
> 	I like both your above answer and the earlier part I have not copied here;  just want to get your views on this list concerns.    
> 
> In our PM testing with cordwood, it is pretty clear that there are no PM emissions from char (other maybe than flyash). We can shut off our sampler early with no difference in results. Opacity testing will confirm this. Therefore, I doubt whether you need to subtract the weight of the leftover char, which would give you an erroneously higher g/kg number. One of the "tricks" in EPA certification testing is to prolong the charcoal phase of the burn as long as possible, which of course reduces your g/h number. Your g/kg number would remain the same. Everything revolves around the magical "EPA number" g/h. It should be g/kg, particularly if you want to compare a wider variety of stoves.
	[RWLA:  We do everything in energy not weight units - so there is no problem with the subtraction (except some who think you can’t).  But it is interesting what you say about seeing minimum emissions after the fuel (mostly wood for you) hs turned to char.  That is the principal of the TLUD, when operated to make money.  Our WBT doesn’t deal with g/h - although it could;  the emphasis in my char-making world is g/MJ  - ad the controversy is over what kind of MJ.   Some want to treat all char as waste!  (This is not my area of expertise, so I hope others will correct me on what is standard in the latest WBT methodology.)

>> 
>> Yes but of course we would be interested in figures for all
>> cookstoves, not just TLUDs.
>> 
>> What I want to know is how cheaply could acceptably accurate and
>> precise (i.e. repeatable) protocol and equipment be made?
> 	[RWL4:   I think Andrew is (tn part) here raising the issue of what we call a WBT - water boiling test.  A certain load for the test.  Do you see anything wrong with a 5-liter standard cookpot of water, where you measure both temperature gain and evaporated loss?  (with arguments about how to handle char.)  Perhaps describing a little more on your thermal equivalent of a reproducible load (with char-making, if you can), valid anywhere on earth. 
> 
> Ha, ha. I met Crispin a few years ago at a workshop that he gave. I knew him from this list, but never realized he was Canadian. I invited him to join our MHA technical committee, where he has made some great contributions to the fundamental science. He has also talked my ear off about the boiling of water test and what is wrong with it (simmering, for example). I have no experience with this whatsoever. Maybe you need to manufacture a “standardized test pot", perhaps with a calibration certificate and a serial number?
	[RWLB  The L’Orange paper looked at that and found no major differences when testing with 6-7 pots.  Recommended near 10”.

>  
> 
> 	 Do you think that your test approaches have helped or hurt your industry?  (EPA and all the other tests.)  And users?
> 
> Definitely helped. We got started with a $100,000.00 project, that was fortunately funded by others, to test masonry heaters and masonry fireplaces at a university laboratory. We didn't know anything at the time, and didn't really learn all that much for the money, except how expensive it was. We realized we needed be able to do our own testing. Fortunately we had a connection to OMNI-Test in Oregon, where we met Skip Hayden and he introduced us to the Condar sampler. We have been able to do some very fundamental stuff like the (PM) repeatability testing on cordwood, that simply didn't exist in the literature. We have a pretty exciting project on the go at the moment in partnership with the Masonry Heater Association of France, to develop a software simulator for possible use in certifying one-off handbuilt masonry heaters. We are also working with Crispin and his new decombustion theory to incorporate additional instrumentation such as measuring flue gas water content, to look at the changing fuel analysis during the batch burn.
	[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?
	 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 <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.

> Our users are heater masons and manufacturers. They have more information on what innovations to incorporate into their own commercial activities. The Austrian eco-firebox is a hot topic at the moment. We are also working with EPA to get a method to certify manufactured masonry heaters, and possibly one-off site built masonry heaters. Our market is so small that the actual difference in the air shed is not much, since we are already clean. We have to compete with dirty “outdoor boilers" in rural areas (and some urban areas like Fairbanks Alaska), that have literally 100X the PM emissions from the same piece of wood.
	[RWLD:   TLUDs face the same dirty competition.  But not by a factor of 100.   I presume the Fairbanks units are not batch - so your and TLUDs are fortunately in the same category.  But I still thin it worth considering whether your system has A BIG advantage of always being batch  I ‘ll bet Kirk could get even better performance if the WBT rules didn’t call for both high and low power (as is needed for cooking).  Kirk?
	Just wondering if the “Alaskan” also couldn’t be batch and also make money while heating.  Just need some short term storage?
> 
> 
> 	I know from watching your video that the emphasis there was on carbon buildup on filter paper.  And “our” tests seem to have some of that.  I personally doubt  that individual “stove activists” on this list will want to get into the detail you showed on your video, but maybe you could say more - and about the other hard one: CO.
> 
> CO is pretty easy. You need a gas analyzer. For wood, you need a minimum of something like a Testo 330-2, which has CO dilution. In other words, when the CO gets above 5,000 ppm, it kicks in 10:1 dilution, which allows you to continue to measure, and prevents poisoning of the expensive CO sensor. There are also some very inexpensive NDIR benches available now, which might portend more affordable CO and CO2 measurements.
	[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)
> 
> 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.

	I have many more questions about how you optimize air flow and other issues related to getting an optimum burn,  and what changes you make and why when you are only combusting the char you have produced.   But that can wait.

Ron

> 
> Best ............. Norbert
> 
> -- 
> Norbert Senf
> Masonry Stove Builders
> 25 Brouse Road, RR 5
> Shawville Québec J0X 2Y0
> 819.647.5092
> www.heatkit.com <http://www.heatkit.com/>
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