Had an invention idea years back related to a work project. Need a passive (unpowered) device, say cigarette pack - to - paperback book size, to produce smoke at a certain temperature limit (~ 500°F) where it is attached. The smoke needs to be reasonably non-toxic, dense, and highly visible even in a high wind, say up to 40 knots. The mechanical parts are worked out but I never could get the ChemE part down. It could be a binary device or could react only to temperature. Is it at all feasible?
I assume you’ve already explored something like these: https://www.grainger.com/category/hvac-and-refrigeration/central-equipment/smoke-emitter-cartridges
But that is quite a lot of wind. It would have to be a pretty large volume of smoke to see it in those wind speeds from any distance; if you aren’t specifically looking for it, that is.
I don’t know the application, but would something like a signal flare not be workable instead?
Unpowered, and produce smoke when the attached substrate reaches 500F.
Glass bulbs in fire water sprinklers come in various temperature ratings. The black/orange one has a maximum ceiling temperature of 475 F. That’s close.
Oils have temperature smoke points.
Make a container, maybe pressurized with an inert gas (no O2/no oxidation), maybe not, with an oil that smokes under 500 F with a glass bulb stopper that breaks at about 500 F. The oil comes out, hits the 500 F substrate, and starts smoking.
The wind aspect is not all that critical but as you say could reduce the visibility; why I included it.
A flare would be great if it was for a boat out in the open; no really safe direction for one here.
The ‘barrier’ part was pretty much worked out with an earlier mention of Sn melting point [or could be an otherwise useless solder to melt out]. But it does need to be forced out of a small aperture to deplete the ‘charge’ slowly. Maybe Nitrogen would do?
Smoke effect for spinning car tire is made by spraying ammonia water on the tire and hydrochloric acid on the pavement. The vapors react to form ammonium chloride. So, somewhat toxic.
Most smoke is made from hot oil vapor contacting cold air. Glycerine is a good non-toxic oil to use for this. Water can be mixed with glycerine to lower the boiling point. Injecting oil into the hot exhaust manifold of a car engine will generate lots of smoke.
To make a smoke generator you want to have hot oil vapor being expelled from an orifice at about 50 psi. The oil vapor jet will mix turbulently with air and condense into droplets like a steam jet would. Water droplets quickly evaporate but oil will not.
A Coleman lantern or camp stove converts liquid fuel to a hot vapor jet to the burner. The same principle can be used to make a smoke generator, except you do not want the hot oil vapor to catch fire (which it can do).
If the generating liquid boils out from a filled cavity I will not have to pressurize it at all. Is that workable e.g. at 500°F? Maybe just need to start experimenting. I am grateful for all the help; it is at least looking hopeful again.
If the oil boils out as a vapor, it may be translucent, i.e. not generate smoke. Yep, best to experiment.
Air is used to pressurize the fluid reservoir. If the pressure in the heated vapor generator is less than air pressure, fluid flows into the generator. Fluid then vaporizes from the heat, and any increase in pressure will push fluid out of the generator back to the reservoir. So pressure stays constant at whatever the air pressure is. The generator is generally just a straight or coiled length of heated metal tubing.
Hot oil vapor is transparent, just like steam. When hot oil vapor mixes with cold air, which is hundreds of degrees cooler than the its boiling point, it condenses to microscopic transparent droplets that scatter light, called smoke. Almost all white smoke or powders are actually transparent solids/liquids.