--- In biofuels-biz@yahoogroups.com, Michael Allen <[EMAIL PROTECTED]> wrote: My guess is that he was talking about unconventional liquid fuels in general.
I think the effect was first noted by the British Army some 60 years ago when they burned sump oil to keep warm in the deserts of north Africa. I'm sorry I no longer have the references but drip-plate burner designs developed at that time have been published. They also noted that used-sump oil containing some water burned cleaner than new engine oil. The water in the fuel has two advantages: In expands explosively to steam and so aids the production of fine oil droplets. And the water vapour reacts with any deposited carbon to form carbon monoxide and hydrogen which happily burn to give more heat. I guess people don't often stop to think that liquid fuels are not themselves flammable: it is the vapour which they form that burns. So anything you can do to increase the rate of vapour production (such as atomising the fuel and pre-heating both it and the air needed for combustion) increases the rate of vapour production which leads to smooth controllable combustion. (Water containing emulsions and separate water sprays have also been used with internal combustion engines to increase efficiency but that is another story) Dissolved or emulsified water can therefore be beneficial because it aids atomisation of the fuel to small droplets and it also turns soot into combustible gases. Provided the water content is not too high, the latent heat required is more than matched by the improved combustion efficiency. 5% to 10% by weight is probably about right for fuels with a high calorific value but IMO perhaps half that should be used with glycerol to avoid chilling the flame. Incidentally, I used one of these British Army designs to make carbon black (channel black) in a small brick unit with a roof made from small pieces of railway line. That may give you a clue as to what happens if heat losses are high! (And the oil we used did contain some water). Insulating the plate (and the whole combustion chamber) with suitable ceramics is indeed a great help in sustaining combustion from fuels with a low calorific value such as glycerol. So, of course, is mixing it with a fuel of a higher calorific value. If anyone is interested in a suitable low-cost insulating material, let me know. Michael Allen 15/01/03 02:24:18, Keith Addison <[EMAIL PROTECTED]> wrote: >>Several contributors have spoken about drip plates. I was advised by a >>prof. of fuel science that dissolving 5% water in the glyc. would cause it >>to vaporise explosively on contact with the hot plate, so improving >>atomisation and combustion completeness. Obviously, you would lose the >>latent heat in the steam, but at 5%, that would be rather small. Anyway, it >>would be quite easy to try for those with a working furnace. >> >>David T. > >Hi David > >Was he talking specifically about glyc, or about the complete >by-product, with soap/FFA and catalyst? > >Best > >Keith > > >Biofuels at Journey to Forever >http://journeytoforever.org/biofuel.html >Biofuel at WebConX >http://webconx.green-trust.org/2000/biofuel/biofuel.htm >List messages are archived at the Info-Archive at NNYTech: >http://archive.nnytech.net/ >To unsubscribe from this group, send an email to: >[EMAIL PROTECTED] > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > --- End forwarded message ---
