It's really good, preheating of air of EPA wood stove ?

[Prometeo]

Combustion air heating, it would increase the volume of air and reduce the oxygen percentage, cars also use intercoolers to cool air, what is the right reasoning?

 

[kborndale]

I think your overthinking this, it isn't rocket science it's burning wood. KISS is the philosophy I use with wood heat

 

[EbS-P]

Extra oxygen is not needed. There is already excess O2. Higher temperatures result in cleaner combustion which results in less pollution and higher efficiency. Win win.

 

[Prometeo]

the thought I had, the comburent air increases the temperature proportionally and exponentially, but running out in a relatively short time, the flame, 2 hours at maximum,
while with cold air, the fire would burn less hot but for longer, because the gas in the wood would not be extracted so quickly, but it would burn more "naturally"

 

[Prometeo]

At 100 degrees C oxygen is zero, it doesn't seem efficient, it means that air passes into the stove, unusable, and the flames disappear, when the stove is hot

 

[Rusty18]

At 100 degrees C oxygen is zero, it doesn't seem efficient, it means that air passes into the stove, unusable, and the flames disappear, when the stove is hot
View attachment 319963

I think that chart is for dissolved oxygen in water. We preheat air to 750c at work before it goes in the combustion chamber on our reactors. We run a little over 1900c on the outlet of our combustors…@2% oxygen.

I have no way to prove it but I would suspect the air temp on my encore is over 200c at the coldest when my stove is running in cat mode.

 

[EbS-P]

At 100 degrees C oxygen is zero, it doesn't seem efficient, it means that air passes into the stove, unusable, and the flames disappear, when the stove is hot
View attachment 319963

This is a graph of dissolved o2 in water. It’s an ideal gas law problem. The stoves intakes room temp air then heats it up and it expands it’s the same number of O2 molecules entering the stove.

 

[ABMax24]

A wood stove and combustion engine run on two very different principles.

A car engine derives its power from the difference in heat at the start and end of the compression/power cycle. The larger that difference in temperature the more power can be made. To increase that delta you want to be able to burn more fuel, which requires more air. The sole job of an intercooler is to increase air density i.e. cram more oxygen in the cylinder so you can burn more fuel.

Gale Banks has a few good videos on this, MAD or Manifold Air Density as he refers to it.

 

[Prometeo]

Sorry for the graph, of water, this should be correct, basically, at 200 degrees C the oxygen is about half, yes, I want to understand how air expands but I don't think fire considers the volume of air but the percentage of oxygen. Yes, the motor discussion is a little different, to avoid self-ignition before the spark, cold air is necessary, but I also think the fire in the stove benefits from fresh air and not heat. Paradoxically warm air has the same oxygen but in a larger volume, Therefore less cold air is needed and therefore the purpose of preheating so as not to lose heat, becomes counterproductive, considering that by reducing the oxygen percentage, the flame may not be created, and therefore we only have air that takes away monoxide and smoke for the flue, instead of continuing the flame.

 

[Kevin Weis]

Okay then. With respect to the above is having a OAK attached t the stove a good thing? Any pressure issues in the house not withstanding. I've always been concerned about cold air coming in the OAK cooling the fire or maybe exacerbating the black glass issues in stoves.

 

[Kevin Weis]

Just to add I didn't think much about this until a few days after I installed my OAK and there was frost all over it on morning when it was about 15f outside. I insulated it after that and had no problems with frost but made me wonder if that cold air was good for combustion of the wood.

 

[Prometeo]

OAK has countless advantages, including air rich in oxygen, which is what is needed to burn, the frost around your oak, it is simply the humidity of the house, condensed in that cold point,
if air does not enter between oak it must enter from other areas, must always enter in the house, better through oak, However, I was discussing my doubts regarding the heating path that this air takes inside the stove, quite obsolete