Dear Ron
" Below you describe Paul's flame as premixed. Unless something has changed (Paul?), I believe the flamelets are of the diffusion type - all secondary air is above the "Belonio burner".." Paul responded a few days ago. "Ron, you are right. Air comes into contact with the gas only after it exits the burner holes. Air does not come into contact with gas before it exits the burner holes. Paul" +++++++++++ I was under the impression Alexis went to a premixed flame based on my understanding of something he said during the demonstration in Bangkok. No problem. That is not a really big issue. Paul O’s burner is quite a bit different from the one Alexis showed. One big difference is the is much harder for air to rice from below and pass between the pot supporting structure and the pot, and also more difficult for hot gases to escape downwards. Something not mentioned so far, and I think I have read all the messages, relates to the burn rate. There is a fan involved and if the burn rate is not the same, then comparing the boiling performance is not going to tell us that much. If the heat transfer efficiency is greater, if the excess air is lower, if the heat escaping below is reduced, and it the heat production rate is higher, then the time to boil is going to be reduced. What would make a better metric is not the time to boil but the thermal efficiency. It is not really a race to boil, it is really striving to be economical with fuel, materials, time and attention. Jim Jetter in the second last PCIA webinar reported the emissions in terms of mass per net MegaJoule gained by the pot: g/net MJ. This is a very useful metric and tells us how much the mass of PM will be per litre boiled, of 5 litres if you wish – just multiply it. The energy needed to boil water is known. If the emissions are given per unit of energy retained by the pot (the net heating accomplished) then the emissions for any quantity of water boiled in that same sized pot can be calculated. As we have pointed out before, the SeTAR Centre testing at multiple power levels and with different pot sizes produces different results for each combination because the stove behaves differently when these are changed. Altitude can make quite a difference to stove emissions per net MJ. This is important information for someone choosing a stove to do a particular cooking task or set of tasks. Once a stove is characterised well, a reasonable projection of its performance is a walk in the park (easy). Regards Crispin
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