I hear you buddy , you just can't hear me....

I noticed this unanswered thread on another site. Mr.Burner throws up a couple of interesting ideas which I would like to discuss except I can't.
My thoughts will follow.
NYBurner,


Im not sure if this has been discussed in the past or not....or is even feasible. The recent discussions regarding stove optimization/efficiency have got me thinking about what options there are truly.
Reading all of these threads and discussions have been great but in some ways pointless as well. I've been waiting to see who would venture into discussion more regarding this....hopefully it is interesting for others as well. At the end of the day we are all trying to optimize thermal heat transfer (out of the burn pot -->exchangers -->convection air output) and there are 2 conflicting ideologies going right now....choke the draft and redirect more air into the fire.

Choking the draft makes the most sense as advice from a manufacture/service perspective as it keeps the stove in manufacture recommended burn temp ranges. Slowing the draft allows more time for the heat exchange to occur, while not affecting the other parameters of the stove operation. It is safe. This bumps extraction efficiency from the fuel used but is not geared to improve the heat exchange rate.

Others are redirecting air or burning a 'hotter' flame to actually get a significant rise in thermal output....This is a stress on the stove itself (albiet likely 'safe') but still a stress. Cheaper stoves with bad metal or thin metal run the risk of burning out components. This method is actually increasing the RATE of thermal exchange by increasing the delta (out of the burn pot -->exchangers) AND again (exchangers-->convection air output). This likely has more loss up the flue.....although with increased heat transfer across the exchangers I am not sure how much net loss there is?

Of the 2 options, I think extracting a hotter flame has given the most feedback in regards to an 'improvement' in output from the community here......and so currently, a higher cfm convection blower, or more thermal mass (turbulators)/better metals are the 2 options of improving the exchange rate in our current configurations.

**Short Attention people here for conclusion**
Has there been any attempt in the past to build a 'smoldering' style pellet stove with an incorporated catalyst?? It seems a pellet stove has everything needed to build a really superior catalyst burner (controlled draft, convection exchange, constant controlled fuel feed). Clean emissions, a REALLY hot burn....any thoughts?

 

My thoughts are the controlled environment of a pellets stove fire gives us the perfect opportunity to tune to the maximum efficiency. Really you should look this as 2 distinct operations; fire and heat extraction.
The fire has clear efficiency parameters. There is a ideal fire temperature and that is where the stove should operate. Luckily (or unfortunately when it comes to improving efficiencies) wood pellets have a wide burn temperature so it is easy to get slack and just have the fire working near enough.
Air washes reduce efficiency as they add an uncontrolled airflow. All air should come through the fire pot, through a sealed oak, preferably via a heat scavenging flue. This allows a level of waste flue heat to ensure a clean operating fire to be recycled allowing feed rates to be reduced to maintain correct operating temp without going below condensation point.
So, no to really hot burn. Wasteful.
Also no to smoldering. Simply a recipe to gum up your stove.
We run a catalyst device in our stoves at all times. It is called a SmartBurn. Great product. I got hammered last time I mentioned it. I don't care, I don't make them but I definitely use them. Incredibly common out here and everyone from wood burners to pellet burners use them. With our ashy fuels we need to carefully clean our stove but no problem with the flues as the SmartBurn keeps them crystal clean. No need for the LBT.
So for fire just run at peak efficiency at all times with minimum draft possible.

For heat extraction; then minimum draft is essential. Maximum blower fan is good but the noise can be annoying. The tipping point becomes what noise can you stand. Our experience is that most stoves are capable of reducing flue temp below condensation point (which is telling you that have gone too far in the heat exchange process) so you just step up from there and your sweet.

It is a real balancing act but not that hard. After all it is only rocket (stove) science...

 

Really a sign of a poorly tuned stove. Just like a car really. Fire temp is critical to clean running. Run em cool and yuck.
The SmartBurns were developed for putting in a wood stove firebox so when put in the top of a pellet stove firebox you need a hot temp to really activate them properly. When we see tiny silver flecks in the fine ash we sweep out of the stove we know it is working. It can't fix a blocked stove and chimney IMHO, even though the blurb says it will, but it definitely keeps a clean stove cleaner longer.
Below is a earlier video I did for our stove owners. It is pretty dark and crappy but it does give an idea of what I am talking about;