Catalytic Heat

[WXYZCIENCE]

I have been working on stirling engines and have been playing around with heat and the efficiency of external combustion. I call the unit my Heat Cat. The first picture is a macro-flame of propane and air. The mixture is adjustable and litered.




The internal diameter of the holder is one inch. It is very hard to keep the flame lite. With the addition of the catalytic beads in this next frame you can see the action of the catalyst on the fuel mixture. The burn chamber will now stay alive as long as the fuel mixture is applied.





In this final picture the heat sink is added to complete the, Heat Cat.





There is a tiny hole on the right side for the exhaust byproducts. At this stage I have no way to calculate the efficiency of this unit. After running the unit for half an hour the temperature stays constant at 180 degrees F.


Joseph.

[RogerAS]

Joseph,

What is that stuff, rabbit biscuits?

See my diary on stirling stuff today.

How much air do u need for cat action?

Auto re lights? Cool.

[WXYZCIENCE]

Roger, the pellets are from a auto catalytic converter.


Looked at your diary. LOTS of info.


A small fish tank pump would run 20 units.


I will use a nichrome wire in the larger unit for lighting.


Joseph.

[willib]

pumpworm you allways have the neatest stuff going on

i was lookig at a honda 750 four crankshaft and thought that would be perfect for your stirling?

[WXYZCIENCE]

Willib, I have a honda 350 crank same stroke as the 750. Looked at that already. I got the Rena crank to work very well. Will try to update the diary next month. Thanks for the input.
Joseph

[dinges]

Hello Joe.

I'm wondering what it is that you are trying to accomplish (i.e. what's the goal) of your contraption. You say it's to increase burn efficiency. However, burning something is already pretty efficient (if you burn all of it, that is). The issue at hand is more to transfer the energy to where it is wanted, as opposed to wasting it on heating things that shouldn't be heated.

I assume you know that the catalytic converter in cars doesn't increase (fuel) efficiency, but converts certain gases to other gases (IIRC, CO becomes CO2, NOx becomes N2 and O2).

I think that if you used small, plain pebbles instead of the pellets from a catalytic converter, you would get the same effect. Might be interesting to give that a try, to rule out whether it's the simple presence or the chemical composition of the pellets that's keeping the flame alive.

Regards,

[WXYZCIENCE]

The issue at hand is more to transfer the energy to where it is wanted, as opposed to wasting it on heating things that shouldn't be heated.


BINGO, Thanks Peter, that is what I am trying to accomplish.You have put it into words for me.


If propane (a basic heating fuel) is burned at 1400K, achieves complete combustion. And in a ceramic block this is how it is done. My question? What temperature does the catalytic bead operate at, and is it as efficient.


I think that if you used small, plain pebbles instead of the pellets from a catalytic converter, you would get the same effect.


I have tried lots of other materials. The beads have a range (my measurement equipment lacks lots but) they will operate at a very low temperature. My question? How efficiently are they burning the gas.
Joseph

[vawtman]

Hello Joe

 I always wondered how those Mr Heaters work not sure if your familiar with them.Use them in my ice shacks.The shacks are sealed pretty tight and have not lost anymore braincells than usual.I think

[GerryS]

The burning should take place at a lower temperature significantly by having the catalyst present.  The catalyst reduces the activation energy for the reaction.  So in this case, if the gas normally burns at 1400, adding a catalyst will lower the temperature needed for oxidation of the gas to 1000 or something (depending on catalyst).  That infact is one of the three purposes of the three-way catalyst.  Unburnt hydrocarbons and soot need to be burned and turned into CO2 instead of being dumped into the atmosphere.  A lot of these hydrocarbons that escape the combustion process and soot that is formed in the combustion process don't oxidize readily at engine exhaust temperatures.  Thus come into play catalysts.  Add some well dispersed platinum onto some high porosity alumina (the beads in this case) and you can burn the soot and hydrocarbons at a much lower temperature.  However, you also have rhodium and palladium in your three-way catalyst beads.  When platinum is present, rhodium and palladium have little effect comparatively when it comes to oxidation.  So the three-way catalyst is not essential here, just the platinum on high surface area/high porosity material.  

[mustang19432001]

If you want efficiency you should try a bunsen burner. We used them in chemistry class. I think you can make one with some threaded pipe, a threaded base, a barbed hose connection and some rubber hose. The long and short of it is when you first light it the burner puts out a yellow flame and when you uncrew the pie half way the blame turns blue.

Cut a couple wide slits into the threads of the base to allow air flow. Before lighting you screw the threaded pipe all the way into the base. After lighting you unscrew it to expose the cuts you made in the base. The heat from the flame draws air up the pipe and generates a cool flame with two shades of blue. The dark blue flame is about 1800 degrees F, the lighter blue flame in the middle is about 2300 degrees F. I'd suggest 3/8" pipe but larger MIGHT work.

It doesn't have a low profile, but the pipe is necessary for the fuel-air mixture. At least with a bunsen burner you won't lose energy with a compresser or a confined exhaust port, and the flame is fairly easy to keep lit.

OK.. the heat sink... one suggestion would be to use the original burner, drill a hole in the bottom to allow the heat to enter and drill more holes in the side for venting. Just remember that a bunsen burner generates alot of heat, and fast. Perhaps another heat sink could have a textured bottom like the piece in the third picture to absorbe the heat from the flowing hot gasses, and to absorbe it best by slowing the hot gasses.

Just a suggestion anyway... the catylist burner seemed a little teedious. Interesting concept... but none-the-less it looked far too difficult for what little it was supposed to do. I'm not even sure if your project could acomodate a bunsen burner or if it could use a unique burner. I still say the bunsen burner is the best way to go. It's easy, and very clean with CO2 and H2O being the primary byproducts with the occasional light yellow flicker producing CO.

[mustang19432001]

unscrew the pie... correction... unscrew the pipe.

can we say OOPS?