An annual problem I have every summer is dealing with smoky campfires when camping. Your bog standard cicle-of-rocks or metal ring fire pit is crazy inefficient, and unless you run continuously in the offgassing phase (bright, tall orange flames, as the wood gas burns off), with lots of convection, you inevitably produce a ton of smoke. This is terrible for all folks, but my asthma-prone lungs get especially cranky. So you either have to continuously feed wood (inefficient and costly), or play the game of shuffling upwind constantly.
I usually end up tinkering and modifying the fire pit to try to eek some better air flow patterns, but it's usually a lost cause with open pit fires.
I might just cave and get one of those stainless inserts, but what I'd really like is something flatpack that I could assemble into a more efficient burner. I've seen small ones [1] that slot together to make a rocket stove, but nothing campfire sized.
I wonder how much demand there would be for such a thing. Seems like there are several products for general "firepit" designs, but without a chimney, these suffer from most of the same problems as open pits. [2][3]
Edit: oh, maybe a "tent stove" is what I'm looking for.
To get mostly-smokeless performance, leave out the bottom metal plate when you assemble it so it gets continuous air flow right through the device. I used to use https://www.solostove.com/en-us (car camping only) and it just burns too* clean - no smoke, hot fire, goes through fuel very fast, and all the heat goes straight up. Still love that thing, but actually for an "improved campfire experience" that collapsible grill thing is excellent. Particularly useful: the heat reflects off the inclined metal plates right on to the people sitting around the fire, in exactly the way it does not on a solo stove.
For those metal ring pits with a cooking grate, you can build the fire on top of the grate for better airflow. If you can get air coming in underneath the fire from all sides, it'll greatly reduce the smoke. And you also reduce the chances of smoke "chasing" the person that's sitting the closest, since they're not blocking a lot of airflow from the sides. Still not peak efficiency, but a lot less smoke.
I repurposed an unused grill lighting thing as a perfect miniature outdoor fireplace. I don’t know the exact name of the device but it is a metal tube 8” wide and 16” tall with a metal grille at one end, inserted up the tube a couple of inches:
Yes, you have to feed it sticks like cookies into a Cookie Monster, but it’s really good for having a snap fire with lots of eat and lots of combustion. Because they are a ubiquitous garden accessory they are also very cheap.
If you're in the US, take a look at Firebox [1] that have a bunch of options through the price range all of which are fairly light. I would suggest going with a biomass stove with some thermal mass (easier to keep the burn chamber hot and also to stop the wind from pushing your stove around) if you're not constrained by backpacking/bikepacking constraints though (e.g. car camping or just going to a park/yard for some outdoor bbq.) You can make one with tin cans and some filler material (there's several guides online) or you can buy something like the EcoZoom [2].
Lots of people don't realize that wet wood generates a lot more smoke and that it takes wood a while after falling off a tree to dry up, so if I'm going by car or by train I often take some dry wood with me to keep the smoke dry.
I've used and researched a lot of portable wood stoves. If you want a portable rocket stove, the one I would recommend is the Virestove. There are some video reviews on youtube that you can check out before buying it. I haven't used a more practical one yet. If you have the funds, they have it in titanium right now. Should be quite lighter than the stainless version. The mini version is more portable of course, but doesn't achieve the smokeless combustion that the larger version does. I guess it's the length of the chimney, but not sure.
For a flat pack grill that's practical and portable, I'd recommend you check out the ones made by UCO. They come in three sizes as of now. The only downside I find with flat pack style grills is that on most of them you have to raise the grill to add wood.
Somebody recommended the Firebox line. They're pretty awesome, but are regular wood stoves. They will smoke just like any fire pit or flat pack grill. No rocket smokeless combustion. The stainless version is very well built and will last forever. Haven't tried the titanium version, but seem to be well like by users. I'd also recommend the Bushbox, by Bushcraft Essentials. These towo are the best of the folding style portable wood stoves (not rocket style).
links to this stuff (some are available on amazon):
virestove.com
ucogear.com/portable-grills/
bushcraft-essentials.com/en/outdoor-stoves/
fireboxstove.com
I have to say though that I've been using wood stoves to cook less and less, mostly because of health concerns. It seems every year I find more and more reasons not to be around them.
What temperatures does this trade off between fewer unburied particles and more NOx production begin to take place? Is it a situation where unburned particles reduce quickly and dramatically as temperature increases and NOx increases slightly until much higher temperatures or is it closer to 1:1?
I really like the idea of using a dual bell system, where one is small and steel and the other’s large and masonry. The thing that triggers me to build/add to a fire is feeling cold, so having quick response is nice. But then of course you want heat mass to avoid dumping all of the extra heat out the chimney.
If my Hearthstone stove ever goes out, I’d like to build one of these.
Is this the same as a rocket mass heater? Appears to be a somewhat different design, but same physics. A rocket mass heater is going to have the burner box outside of the bell.
Any reason you couldn't have bells on separate floors? I.e. core and a bell on floor one that leads to a bell on floor two before exiting through a chimney?
It's not immediately clear what the difference is between this and regular rocket stoves.
I think (I could not find a clear description that was short and easy to understand, maybe I missed it) that it has a door on the box where the wood goes in, and a pipe that feeds fresh air into that box to keep the combustion going.
To add a bit of context to the sibling comment, rocket stoves can work when made out of pretty much any material, because the air flow is not tightly regulated.
Batch box's purpose is to allow a more full-sized fire with the efficiency of a rocket stove, and there are several key differences to hit that:
- It should be made of a refractory material. Rocket stoves function perfectly well with plate metal or anything, really
- All dimensions, especially the air inlets and heat riser, must match a specific set of ratios to preserve the specific airflow needed to maximize burn efficiency. Too much means air will move too quickly, preventing full burn
- A choke point between the burn chamber and riser exists to slow down and funnel gasses and heat together. Without this, you don't have enough heat to get full combustion
Batch box burners tend to be quite a bit more fussy than a rocket stove to get going, though if a good portion of your exhaust rise is inside and pre-warmed, it should have a strong enough natural draft that starting it isn't much extra effort. I toyed around with the dimensions a bit myself and have something that works really well (cylindrical chamber rather than block), though I don't think I'm getting optimal efficiency out of it.
The difference is that in a normal rocket, you need to keep feeding the fire at regular intervals because the feed tube is so small. In the batch box you load it once and let it burn.
[+] [-] kortex|3 years ago|reply
I usually end up tinkering and modifying the fire pit to try to eek some better air flow patterns, but it's usually a lost cause with open pit fires.
I might just cave and get one of those stainless inserts, but what I'd really like is something flatpack that I could assemble into a more efficient burner. I've seen small ones [1] that slot together to make a rocket stove, but nothing campfire sized.
I wonder how much demand there would be for such a thing. Seems like there are several products for general "firepit" designs, but without a chimney, these suffer from most of the same problems as open pits. [2][3]
Edit: oh, maybe a "tent stove" is what I'm looking for.
[1] https://www.amazon.com/Marsh-Kettles-Flat-Rocket-Stove/dp/B0...
[2] https://www.amazon.com/Flat-pack-firepit-grill-carry/dp/B086...
[3] https://www.etsy.com/listing/799723294/flatpack-firepit-port...
[+] [-] leashless|3 years ago|reply
This is dirt cheap, light-ish, and excellent.
To get mostly-smokeless performance, leave out the bottom metal plate when you assemble it so it gets continuous air flow right through the device. I used to use https://www.solostove.com/en-us (car camping only) and it just burns too* clean - no smoke, hot fire, goes through fuel very fast, and all the heat goes straight up. Still love that thing, but actually for an "improved campfire experience" that collapsible grill thing is excellent. Particularly useful: the heat reflects off the inclined metal plates right on to the people sitting around the fire, in exactly the way it does not on a solo stove.
It's really good. Makes me happy.
[+] [-] stronglikedan|3 years ago|reply
[+] [-] gorgoiler|3 years ago|reply
https://image.dhgate.com/0x0/f2/albu/g9/M00/38/77/rBVaVV7PBK...
Yes, you have to feed it sticks like cookies into a Cookie Monster, but it’s really good for having a snap fire with lots of eat and lots of combustion. Because they are a ubiquitous garden accessory they are also very cheap.
[+] [-] Karrot_Kream|3 years ago|reply
Lots of people don't realize that wet wood generates a lot more smoke and that it takes wood a while after falling off a tree to dry up, so if I'm going by car or by train I often take some dry wood with me to keep the smoke dry.
[1]: https://www.fireboxstove.com/index.php?route=common/home
[2]: https://ecozoom.com/
[+] [-] pnutjam|3 years ago|reply
[+] [-] EL_Loco|3 years ago|reply
For a flat pack grill that's practical and portable, I'd recommend you check out the ones made by UCO. They come in three sizes as of now. The only downside I find with flat pack style grills is that on most of them you have to raise the grill to add wood.
Somebody recommended the Firebox line. They're pretty awesome, but are regular wood stoves. They will smoke just like any fire pit or flat pack grill. No rocket smokeless combustion. The stainless version is very well built and will last forever. Haven't tried the titanium version, but seem to be well like by users. I'd also recommend the Bushbox, by Bushcraft Essentials. These towo are the best of the folding style portable wood stoves (not rocket style).
links to this stuff (some are available on amazon):
virestove.com
ucogear.com/portable-grills/
bushcraft-essentials.com/en/outdoor-stoves/
fireboxstove.com
I have to say though that I've been using wood stoves to cook less and less, mostly because of health concerns. It seems every year I find more and more reasons not to be around them.
[+] [-] wespad|3 years ago|reply
https://news.ycombinator.com/item?id=6895582
https://news.ycombinator.com/item?id=20075110
https://ludens.cl/paradise/turbine/turbine.html
[+] [-] littlestymaar|3 years ago|reply
Higher temperatures lead to lower amount of unburned particles, but also lead to NOx production. That's what the WW scandal was about by the way.
If you want clean combustion, you need high temperature + SCR[1]
[1]: https://en.wikipedia.org/wiki/Selective_catalytic_reduction
[+] [-] voisin|3 years ago|reply
[+] [-] TacticalCoder|3 years ago|reply
Honest question: compared to which pollution if the wood is let to rot in nature? For it'll eventually decay too.
[+] [-] jonstewart|3 years ago|reply
If my Hearthstone stove ever goes out, I’d like to build one of these.
[+] [-] CrazyPyroLinux|3 years ago|reply
[+] [-] tylerag|3 years ago|reply
[+] [-] ShroudedNight|3 years ago|reply
That being said, I'm intrigued to try the 'core' design in something like a pizza oven to see how it performs.
[+] [-] jollyllama|3 years ago|reply
[+] [-] leashless|3 years ago|reply
I think (I could not find a clear description that was short and easy to understand, maybe I missed it) that it has a door on the box where the wood goes in, and a pipe that feeds fresh air into that box to keep the combustion going.
Did I get that right?
[+] [-] zdragnar|3 years ago|reply
Batch box's purpose is to allow a more full-sized fire with the efficiency of a rocket stove, and there are several key differences to hit that:
- It should be made of a refractory material. Rocket stoves function perfectly well with plate metal or anything, really
- All dimensions, especially the air inlets and heat riser, must match a specific set of ratios to preserve the specific airflow needed to maximize burn efficiency. Too much means air will move too quickly, preventing full burn
- A choke point between the burn chamber and riser exists to slow down and funnel gasses and heat together. Without this, you don't have enough heat to get full combustion
Batch box burners tend to be quite a bit more fussy than a rocket stove to get going, though if a good portion of your exhaust rise is inside and pre-warmed, it should have a strong enough natural draft that starting it isn't much extra effort. I toyed around with the dimensions a bit myself and have something that works really well (cylindrical chamber rather than block), though I don't think I'm getting optimal efficiency out of it.
[+] [-] davidvd|3 years ago|reply
[+] [-] leke|3 years ago|reply
[+] [-] stevespang|3 years ago|reply
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