I’m just going to give you my take on it. Over the years I’ve had many projects. I did a lot of research on homemade batteries and made quite a few homemade batteries. Also I did a lot of research on thermal acoustic engines and managed to design some rather large engines that have good performance for their type. And I always messed around with making wood gas cook stoves and just wood burning stoves. I began to realize that what makes a battery more efficient can be applied to a wood gas generator and even more so when I learned about thermal acoustic engines plays a big role in making a wood gasifier more efficient. I’m not saying that I’m correct but this is just my take. As with any battery in order to prove efficiency you need to increase surface area. And air electrode will give you a good example of what small passages through a construct will do. The amount of contact increases dramatically. So I figure that the typical downdraft gas fire is not that efficient because the combustion zone has a lot of mass and is compacted therefore not allowing air to flow through easily. Also the pyrolysis zone is backed up and it’s also too large for the combustion zone to process. I don’t even know if I’m using the correct terms here as far as the gasifier goes. I’m calling The mass of glowing carbon the combustion zone. It’s so large and hot that a lot of the residual heat rises and makes for a large mass of pyrolysis zone. If you base it on the air electrode it’s not about the mass it’s about how much glowing carbon surface area you have, and when it’s compacted air passing through tries to go around it because it’s just too thick and compacted. So with this design the glowing carbon is nice and fluffy and has micro passages all through it. Also it’s not very thick but very hot. Pyrolysis takes place just below this glowing carbon and the transition is rapid. The glowing carbon is full of micro passages which can be interpreted as the stack on a thermal acoustic engine. On a thermal acoustic engine you transition from cool air to hot air very rapidly and when this happens air velocity is increased. So the hot glowing carbon is the stack with all of its micro passages The cool air passing through is instantly superheated and converted to flammable gases. But it’s also accelerated just like the thermal acoustic engine. You’d be surprised how much more surface area there is coming in contact with the air because of those passages. Also excess heat is carried away and does not creep into the wood pellets very far causing a backlog of pyrolysis. It’s my opinion if you’re gas has a lot of moisture then the proportions are off. There should be no moisture passing through that wall of glowing carbon and if there is, proportions need to be adjusted.
Like I said this is just my take on the topic and I’m not saying that it’s correct. I’ve been retired for about 6 months now and I have always enjoyed trying to figure out how things work and tried to come up with new approaches. I have other interests also I have designed and built many firearms and currently I am patent pending on an original new gun design. And yes I cannot apply any gun designs to this wood gas generator. 
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