Two questions for folks more knowledgeable than I:
1. how would one tie a rocket mass heater into an essential oil still, and is it even possible without boom squish?
2. what are the best options for installing a rocket mass heater in a trailer/tiny house where there are severe weight limitations? Can the masonry/cob be lightened with perlite or vermiculite, or even fiberglass fibers?
I'm rehabbing an old trailer, and I'd like to avoid a mini cast iron stove if possible. They just don't seem efficient enough to me.
I think you could combine a rocket mass heater and essential oil still, but you might want to include a switch to bypass the mass, especially in a small space like a tiny house. otherwise, it would be very easy to overheat the space and make it very unpleasant to operate.
on the weight issue: blocking the trailer up under where the stove is would help while it's parked. making the mass removable might be necessary if it's going to be mobile.
I probably should have been more specific, tel; the rocket heater for the still could be portable, because I would be processing herbs outside for EO, but the heater in the trailer must be permanent. I don't want to waste any heat energy, so I definitely want some thermal mass, but lightweight.
Sage Radachowsky, a tiny house fan, mentioned that micronized paraffin might be a good thermal sink, but the cost and weight is still big. I debated maybe piping the hot exhaust thru the flooring of the trailer (like air conditioning in reverse) but don't know if the temps would do something to compromise the trailer structure. I would block the trailer no matter what once it was parked, but it still needs to roll and conform to the 7700lb. limit per the DMV.
lightweight thermall mass would be something of a holy grail.
for the trailer, I bet you could use water as your mass. I'm imagining a propane water heater with the guts and insulation removed layed on its side. or maybe a couple in series. the water could be drained when it's on the move. there are significant hazards involved with heating water, though, so precations would very much be in order.
outdoor rocket still? I'm quite certain that's doable. take care to isolate any flammable vapor or oil from hot spots and flames.
So you think, Tel, I could find a mini cast-iron radiator and plumb it to the rocket? Hmmmmm...I'll have to run that by Deek Diedriksen and the boys at Tiny Yellow House...
As for the Essential oil still, I'm not sure how I would plumb that. The heater must heat the bottom of the still (just like a propane heater), but perhaps a plain ol' quickie brick rocket with a real short vent pipe would do the trick. (maybe I'm overthinking this one...)
Jennifer Jennings wrote:So you think, Tel, I could find a mini cast-iron radiator and plumb it to the rocket?
I do think you could. I also think that you should think long and hard about how you're going to eliminate any risk of steam explosion. it can and has been done, but caution is most certainly in order.
planning a similar contraption for a friend's bus. we'll see...
still: I'm thinking you would want a thick bottom on whatever your vessel is and to situate your condenser well away from any heat. a quick and dirty rocket could work, but if it's something you'll be using a lot, you may as well design it to be more efficient and adjustable and user-friendly.
I'm thinking you would want a thick bottom on whatever your vessel is and to situate you condenser well away from any heat.
Fortunately, I have several welder friends who might be interested in this project, mostly because they don't want to see me spend 6K for a distiller of the size I want/need. Part of the design process will have an extended neck into the condenser.
I'd love to know what results you get from your friend's project, and I wanna see pictures when you do. Thanks for all the advice, Tel!
I don't know how mobile your trailer is going to be? if not too mobile you might try digging in your thermal mass under the trailer, insulated in the earth or box of gravel on top of earth with associated ducting. Park trailer over TM and skirt trailer preferably with some type of insulated board.
I never considered having it outside, Tarkus, but that could work (especially since Paul has put together a portable one). Connecting it and feeding it wood might be a bit tricky, unless I put some kind of trapdoor...
Perlite or vermiculate to lighten the thermal mass would also make it less efficient - they have a lot of entrained air in them and do a good job of insulating (insulating=slowing down the process of heat transfer) meaning less transfer of heat from the exhaust before it is vented outside. You could compensate by having a longer run through the TM, but that would require more TM which would weigh more overall. There is really no way to escape the need for mass in the thermal mass - except by using costly phase-change materials like paraffin (also flammable).
Two ideas - complex and simple.
From all that I've heard what you need for good TM is direct contact with the exhaust run from a highly heat conductive material - cob being the practical optimum - which in turn is embedded with high mass material for heat accumulation (rock, brick, stone rubble).
For a tiny house on a trailer you need something which is permanently installed - but is low weight when the home is in transport mode.
It really sounds like water could be the answer. Very conductive, plenty of mass, very portable, easily drained out when necessary, safe and nonflammable (but provision would have to be made to safely vent steam in case of overheating). The amount you use would have to be carefully thought out - you can't let it get hotter than 100C (212F), so the total volume would have to be fairly high so that it can absorb a useful number of BTUs without transitioning to steam.
I am imagining a heat bench with a short run of conventional cob/stone TM at the hot end of the exhaust run, but with the remainder essentially a series of water containers with a relatively small amount of cob between containers and in direct contact with the exhaust duct - like a cob honeycomb. It would be quite massive in weight, but a good portion of that mass could be drained out.
But ... Perhaps you should just go simpler.
Your house, all its furnishings, and even the air inside it, is thermal mass. Assuming your tiny house is well insulated, you can just utilize the home itself as your thermal mass. When not in transport mode you can add to the home's mass by using water drums as table supports, end tables, etc. (as a bonus you have a good supply of emergency water). They'll retain the ambient indoor temperature - which in cold weather you can maintain by more frequent firings of a small RMH stove without built in TM. Yes it will be less efficient than a big thermal mass unit that recovers a large amount of the exhaust heat, but it will still be better than a conventional furnace or wood stove.
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