Odds and ends

Moderator: Mike Everman

Re: Odds and ends

Postby Mark » Tue Aug 23, 2016 5:26 pm

Well an initial test of the high pressure air tank proved fussy. Maybe with the snorkel the beveled/rounded bottom reflects the combustion in an adverse way or maybe just being almost 2 inches shorter than the 20 ounce tank is a factor or both. I have never liked round bottom "jam jars" as much as flat bottom ones.
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Re: Odds and ends

Postby Mark » Sun Sep 18, 2016 5:28 pm

So I tried the high pressure aluminum air tank again with a shorter 3.75 inch snorkel and it ran well enough sideways but it doesn't sustain in the vertical which is the same behavior for the other (CO2) paintball tanks with a longish snorkel.

In other news I was revisiting an idea of using a typical jam jar to run it on paraffin wax. The idea being like melting a glass beer bottle that is slowly moved closer and closer to a campfire, it won't crack and as such perhaps gradually heating a jam jar with wax for fuel until it starts to smoke or reach the autoignition temperature, would have a chance of working. It might need some puffs of air to air out the jar for starting. One thing about wax as opposed to a low boiling point methanol is the fuel could be considerably hotter instead of how methanol would be sloshing against the sides of the glass making it more likely to crack, usually right at the fuel level. Thus the heat gradient between the melted wax and jar could be such that the jar might be less likely to crack.

He's putting the test tube in water whereupon the tube cracks and the erupting steam carries the vapor up and since the wax is hot enough, all it needs is air to light.
Autoignition of boiling paraffin (candle wax)


I was watching these gasoline powered jam jars and it dawns on me that much like starting a Dyna-Jet on gas, it might help if you preheated the gasoline. Dyna-Jets are easier to start if hot or until you get a few false starts to heat it up. It seems counterintuitive though, because a jam jar might become too rich to start if not careful, the vapor being heavier than air displacing the oxygen.
"After 45 minuets of trial and error, this was the end result. Unfortunately were missing about 15 seconds of footage at the start, including the lighting of it which burnt a 2cm hole in my glove."

Note the delay in starting as the flame dwindles and sits on the surface of the gasoline for a bit before the main pulsations start up. This happens with methanol too sometimes.

"Paraffin wax is a white or colorless soft solid derivable from petroleum, coal or oil shale, that consists of a mixture of hydrocarbon molecules containing between twenty and forty carbon atoms. It is solid at room temperature and begins to melt above approximately 37 °C (99 °F); its boiling point is >370 °C (698 °F)."

"The boiling point of methanol is 64.7 degrees Celsius, or 148.46 Fahrenheit."
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