[Stoves] Top lit updraft combustors

[Law, Steven (MOECC)]

Thanks Norbert, I will take a look at this and see how to use my new calculation model to support this method.

For example, I do everything on a wet basis, so all the moisture in the wood fuel is accounted for in the mass balance. I even separate the H2O in the flue gas generated from the combustion of hydrogen in the wood from the evaporated moisture in the wood fuel. These two quantities of H2O are then added together in the wet flue gas.

I also have a dry volume basis calculation since that is how the dry flue gases are measured in the field. I designed the model to blend both lab analysis data for the wood and LHV efficiency with field data for emission measurements and HHV efficiency. It should be fun to figure this all out.

From: Norbert Senf [mailto:norbert.senf at gmail.com]
Sent: December 18, 2017 11:43 AM
To: Law, Steven (MOECC)
Cc: Ronal W. Larson; Discussion of biomass; mhatech at yahoogroups.com; Sauve, Terrence (OMAFRA); John Ackerly
Subject: Re: [Stoves] Top lit updraft combustors

Thanks, Steven. That's great.
Our experience with domestic-scale cordwood in masonry heaters (50 lb batches @20% moisture) is that the "boiling of water" or latent heat loss is typically in the 13% range, using the Condar spreadsheet HHV calculation   heatkit.com/docs/condar.PDF<http://heatkit.com/docs/condar.PDF>

On Mon, Dec 18, 2017 at 11:24 AM, Law, Steven (MOECC) <Steven.Law at ontario.ca<mailto:Steven.Law at ontario.ca>> wrote:
Hello all,

I have finally completed a proper study of reporting efficiency using LHV and HHV. It was much more complicated than I thought it would be, and now I know why this is such a mess!

Just remember that HHV is always less than LHV, and anything above 100% is WRONG and cannot possibly conserve energy or mass and is therefore unscientific.

When an LHV efficiency from Europe is 90% (which is actually a reasonable number), the HHV efficiency is a maximum of 84% or usually less, depending on the moisture content of the wood fuel and is more typically 75-80%. This is important, HHV efficiency is extremely dependent on fuel moisture whereas LHV is less so, but only for non-condensing boilers.

Again, this is for non-condensing combustion devices, because when you throw in high efficiency condensing heat recovery all the numbers get screwy and LHV no longer applies. Everything has to be re-done for condensing boilers and only HHV can be used, I will repeat LHV cannot be used for anything where condensation of the flue gas occurs in the heat recovery device!

I think I have a proper engineering calculation procedure mapped out to deal with all of the above issues and I will begin to roll this out a little bit at a time since I need to review it again before sending anything out. It is a scientific method that is based on conservation of mass and energy and I hope that this new calculation procedure will help to solve some current problems in the industry.

Best regards, Steven
--
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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