There’s an iron I love that has a steam generator onboard. I think it might be a good thing to hack. Use a camel back for water storage. Make a handle to keep it close to the ground. Keep it light weight and portable.
What James said about real world losses and insulation. Just so I could get a handle on the basics here energy needed to boil water. I like to see the values, so I dumped it into a spreadsheet.
I think by the numbers I could come up starting from 50F worse case from a tap to 100F water you are in the range of 0.25L per min under a 15A circuit.
This seemed to be first site that gave info. They had north of 10L/m, but that is someone doing it commercialy for $. https://www.weedtechnics.com/
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If you start with near-boiling water in the reservoir, you’ll save tons of juice trying to heat it so far. We don’t happen to have a near-boiling Artesian spring nearby, do we?
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Just for clarification do I read that as Ar-teez-Ian, or Art-eh-zen?
And no. I’m actually surprised we haven’t set up an automated weed frying system on raspi and a frenzel lenses.
Your cup doth boil over David…
Def agree, even hot tap speeds it all up considerably
Not too much is saved with a water pre heater. As long as it’s liquid, the difference between boiling it off and raising it from 0C to 100C then boiling it off is only about a fifth extra. (2257kJ vs 418.4 kJ + 2257kJ (2675 total) for 1 kg (L) of water)
@tom.bloom’s spreadsheet didn’t look right to me, and I recalculated it, and after a while wondering if I was off, found the issue: 1 degree temp rise (specific heat) = 4.184 kJ/kg (or J/g), heat of vaporization = 2257 kJ/kg (Note decimal point, cell C2.) Though it often seems to be written as 2.257 kJ/g, which while accurate if used with J/g or kJ/kg makes missing that an easy mistake. Once corrected it lines up with my calculations. After talking with him, I think that’s what happened.
My calculations get ~2.4 L/hour from 1800W (15A circuit, 120V) Without losses. (Hah!) or a flow rate of about 0.04 L/min. Mind you stream greatly expands, with nothing confining it and such is something like a 1500x increase in volume.
While the commercial ones listed are 20x+ more powerful (based on diesel fuel rates listed) they seem to be a bit off. Continuous, I get about 60L/hour (but they are inconsistent on on units used in their marketing, Two of them one, noted at 4.7L of diesel/hour and another at 5L/hour one claims 5L/min, the other 5L/hour. If the burner is put into only burning it gets about 75-80L/hour per my calculations. But they could be using super heated steam (boil the water, then add heat to it to add extra energy, which is for comparison is about 2.08 kJ/kg (Half that of water) which is also what @james.a.seymour 's youtube link does.)
For another comparison: a kitchen stove is going to be up to about 3000 W heating element (Though most standard 8" ones seem to be 2200W, with 1500W for the 6" ones) can only burn off about 4-5L/hour.
As far as repurposing something else, a lot of things like the HF one mentioned are close to the limit, and without a 208V/240V circuit, you’ll have to have multiple 120V circuits or burn fuel.
And a 2m fresnel lens from a 100" projection TV (assuming focused without any difficulties like melting things, might actually be a very good option) Also assuming the lack of losses, there’s about 1000W/sq meter from solar. Assuming minimal losses (as we aren’t trying to convert the solar to electricity, which would have 10-15%) : When sunny that would outperform a 120V system for making steam. (@james.a.seymour 's death ray pi aside, which would probably work… at least until the first wind storm.) We could probably make a local steam machine with a smaller one. But compared to the ~400kW (quick estimate based on roughly half the garden) that solar is providing, trapping even a portion of that is probably better.
Though admittedly, that 20% when trying to boil water, will certainly slow it down from never boiling, if watched. So to achieve efficiency we should by conventional wisdom, never watch it.
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