Sciencemadness Discussion Board - Pressurized Gas production.

Pressurized Gas production.

tom haggen - 4-11-2004 at 20:24

Hello, everyone.
I'm embarking on a quest that involves a high energy out put of pressurized gas. The first thing that came to mind was this reaction:

2NaN3(s)---->2Na(s) + 3N2(g)

The energy out put in this reaction is great which makes it appealing to me. However, you are left over with very reactive elemental sodium. I’m trying to harness the energy for some type of propulsion system, for a small appx. 16oz vehicle. The desired properties for of reagents are that when they react, they produce large amounts of gas with no other byproducts such as solids, liquids, or poison gases. I'm thinking I want something that will produce large amounts of gas with minimal amounts of reagents. Conventional explosives are not candidates for this experiment unless they are considered to have some sort of use as a reagent. Any suggestions?

BromicAcid - 4-11-2004 at 20:43

I once tried to make a hydrogen candle type thing, I drilled a hole in the top of a pop bottle and put in a handful of galvanized nails and added some HCl. Gas started coming out and I ignited it, of course the flame was colorless but it roared, but gas production was too great, the bottom rounded out and it fell over, then propelled itself about fifty feet, exploded and the hydrogen exploded separately form the mechanical explosion. But the byproducts are of course ZnCl2 and such, but without ignition the hydrogen could be safe. And of course you could substitute zinc with iron or aluminum or magnesium.

Excess MnO2 and concentrated H2O2 can make large quantities of O2 quickly that could be used to propel an object. And your only byproducts are going to be water and O2.

There really are not too many gasses that you could use that would not be hazardous in some way, oxygen is probably the most benign. Maybe you could use some sort of xenon fluoride, with aluminum, forming solid aluminum fluoride and xenon gas. But that's stretching it a bit. There are of course ways to produce nitrogen involving reacting sulfamic acid with sodium nitrite but that's somewhat of a waste if you ask me. The best gas would probably be carbon dioxide, but of course that is the most time tested method, like a bottle with water and dry ice, or a vinegar and baking soda volcano.

tom haggen - 4-11-2004 at 22:35

I don't know if my mind is just going blank or what, but I’m just having a hard time coming up with something off the top of my head. You would think after a year of blowing shit up and burning metallic objects in strong acids I would be able to come up with something. I guess I might as well go ahead and say that this is a project for my engineering class. The rules are that you have to use a chemical reaction to propel a small plastic vehicle 25 feet. No brakes can be used; therefore the only way for the vehicle to stop is when the reaction is complete. The project can't leak water or drip water, and it can not expel smoke (so no rocket engines). The only feasible way of propelling the vehicle is going to be with some kind of pressurized gas stream. If any gas is expelled it has to be calculated via stoichiometry. The problem I’m having with visualizing this project is this:
for example, if you use vinegar and NaHCO3 it will produces some CO2 but as CO2 spews out in a high pressure stream through some type of valve you are also going to probably be dripping some vinegar unless you make vinegar your limiting reagent, but if you do that then you are probably going to spew out some access baking soda. Also, my professor said that he will order any chemical we need for our groups design. This was sweet sweet music to my ears. For the first time in my life I have access to any chemical I want and my mind goes blank... I'm also going to need to find some kind of propulsion formulas. That way I can calculate how much pressure I will need to send a certain weight exactly 25 feet. I have five weeks so it's not a time crunch. But I really would like to try and use some sort of exotic reagents since I have access. The only catch to that is, my budget is only 15 American dollars.

[Edited on 5-11-2004 by tom haggen]

[Edited on 5-11-2004 by tom haggen]

vulture - 5-11-2004 at 13:38

Try a concentrated solution of ammoniumnitrate and potassiumcarbonate...

The ammonia stench isn't very pleasant though...

WARNING: This reaction can be violent, be prepared.

neutrino - 5-11-2004 at 14:57

Sodium azide is used in air bags with other stuff to take care of the sodium formed. I think this mainly consists of beningn stuff you could find anywhere.

edit:
I didn't think this deserved a new post, but would it be feasible to filter out any solid components produced using some kind of filter like glass wool?

[Edited on 6-11-2004 by neutrino]

kyanite - 5-11-2004 at 17:44

Yeah it's iron oxide they use. Your right, you can find that almost everywhere

It oxidizes the sodium so the driver doesn't get sprayed with atomized Na

Wow, I wish my school wasn't that cheap... Our lab experiments consist of questions like what happens when you dissolve salt in water...

On Sam Borrows site he does this thing with liquid nitrogen and warm water in a pop bottle rocket

. High gas output, non-toxic materials, and left over liquid nitrogen to play with when your done with your quest

http://www.powerlabs.org/rockets.html

Edit: If your worried about the water, I guess you could use less

[Edited on 6-11-2004 by kyanite]

tom haggen - 5-11-2004 at 23:19

Actually the reaction in an air bag uses potassium nitrate to stablize the elemental sodium created by the sodium azide reaction. So an ammonium nitrate solution will react violently with potassium carbonate then... I didn't realize that NH4NO3 was so acidic that it would react violently with a weak base like K2CO3.
By the way, I really like that glass wool idea you had neutrino.

What exactly initiates the sodium azide reaction? I assume it would be heat?
[Edited on 6-11-2004 by tom haggen]

[Edited on 6-11-2004 by tom haggen]

neutrino - 6-11-2004 at 06:27

The reaction of potassium carbonate and ammonium nitrate is not due to an acid-base reaction. It is due to the formation of ammonium carbonate, which easily decomposes:

NH4NO3(aq) + K2CO3(aq) <-> 2KNO3(aq) + (NH4

2CO3(aq)

(NH4

2CO3(aq) -> 2NH3(g) + CO2(g) + H2O(l)

vulture - 6-11-2004 at 14:35

Not really, the fact that ammoniumcarbonate decomposes is because you have a base and an acid in one molecule.

As a result this reaction IS an acid-base reaction:

NH4+ <----> NH3 + H+

CO32- + 2H+ ---> H2CO3 ---> H2O + CO2

Magpie - 6-11-2004 at 21:43

Consider a voltaic cell driving an electric motor. But I don't see how to stop it at 25 feet. This is probably not what your professor has in mind.

The solid or liquid entrainment proplem should be solvable with a knock-out screen of some sort, as previously mentioned. Consider kitchen srubbing pads. A zig-zag path filled with scrubber pad might work. You don't need much of a punch to go just 25 feet. A chemical reaction that is somewhat controllable like baking powder with vinegar added slowly via orifice might do it.

tom haggen - 6-11-2004 at 23:54

Actually polverone and I have been exchanging U2 messages about using some type of electric cell. He mentioned using a timer circuit to turn off the power. Its definitely an option I'm keeping in mind.

[Edited on 7-11-2004 by tom haggen]

neutrino - 7-11-2004 at 06:00

It appears that ammonium carbonate is actually stable up to 60*C, so all you’d have to do is heat a known quantity and it would completely decompose. With this in mind, Vulture’s reaction shouldn’t happen, though…? Could this be one of those things where it slightly decomposes at STP and reaches equilibrium in a sealed container, preventing further decomposition? Or maybe it would have something to do with the slightly elevated pH caused by an alkali carbonate?

kyanite - 7-11-2004 at 09:22

That sounds like that reaction that liberates ammonia from any ammonium ion by reaction with NaOH.
Like NH4NO3 and NaOH -> NH3, NaNO3, H20. Is that what your going at?

Organikum - 7-11-2004 at 11:09

tom haggen, I believe the solution would be a piston connected to a wheel or axis of the cart. The movement of the piston and the diameter of the wheels define an exact way the cart moves.
Providing a reaction which makes the piston move a defined amount of strokes is possible IMHO, the lesser strokes the easier this comes.
A big-volume cylinder and a reaction as heatsource, some calibration for the losses, thats it. The reaction could be even sealed, hot air as driving force (for free whereever ppl talk.....)

Of course I dont know if such a setup is inside the rules of the task.

vulture - 7-11-2004 at 13:09

Quote:

It appears that ammonium carbonate is actually stable up to 60*C, so all you’d have to do is heat a known quantity and it would completely decompose. With this in mind, Vulture’s reaction shouldn’t happen, though…?

Ammoniumcarbonate is stable when it's dry, because it isn't ionised then. In solution or when being melted however...

Magpie - 7-11-2004 at 19:32

It seems that unless you use a timer or a gearing mechanism with a limit it is going to be difficult to go exactly 25 feet.

The trouble with a gas propulsion reaction is that it is momentum driven. Momentum depends not only on the mass expulsion rate but also the velocity of expulsion. A simply built gas expulsion mechanism would likely ramp up then down, so trial & error are involved to get the distance. Then back- calculate to get the theory right to satisfy herr professor. So it looks like a lot of work (fun) and possibly a bit of money to make this work well. Is there a prize for 1st place? Money, women, or "engineer of the week" maybe?

What is the course you are taking and the discipline of the professor? I know you have your rules but this information may help to understand what the prof is really looking for.

Taaie-Neuskoek - 8-11-2004 at 00:14

Just an idea, I don't know or this is allowed, or practical.

The enigine can be anything, as long as it comes further then 25ft. If you are allowed to draw a white fat line at 25ft, it is easy to build/purchase a print which recognizes the white line, and then brakes the car via a relay and a motor, just disable the wheels one or another way...electromagnets are good as well for braking...

To recognize the white line you'll need something like a licht sensitive diode, with a transistor and a relay coupled to it. The transistor triggers the relay.

[Edited on 8-11-2004 by Taaie-Neuskoek]

tom haggen - 8-11-2004 at 09:21

The class is a freshman chemcial engineering course. There is no prize. The professor is a Dr. and specializes in polymers. He said that a lot of times someone in one of the groups will come up with a really good idea and then all the other group's projects will start taking the same form. Since this happens, he allows a fake pattent on your project which he issues. I have lab on thursday so after then I will probably have a much better idea on what exactly i'm going to be able to do for this lab. I.E. electric cell, a huge piston attached to the cart, etc...

oh ya new guy with the scandinavian name. No Breaks Allowed!

[Edited on 8-11-2004 by tom haggen]

Organikum - 8-11-2004 at 10:18

The decomposition of sodium bicarbonate at temperatures of 50°C+ to sodium carbonate yields CO2 and might be a easy, low-temp and non-toxic gas-source. Simplicity and availability.

I define here everything below the boiling point of water as low-temp.

mick - 9-11-2004 at 06:18

Not sure how complicated it can be, but maybe you could use a fast reaction to power up a fly wheel or clock-work mechanism or some thing with overload protection (a polymer that shears at the right torque or a bursting disc to vent xs pressure) and a basic clutch to engage at the right time. The fly wheel or whatever should hold a known amount of power.

mick

[Edited on 9-11-2004 by mick]

Magpie - 9-11-2004 at 13:15

Gasoline engines use chemical reactions. A model airplane engine could be used as a power source.

In line with mick's suggestion you could use the power source to wind a spring. This would store an exact and reproduceable amount of energy for release to the drive train.

garage chemist - 9-11-2004 at 14:02

I would use high conc. H2O2 and a solid catalyst on an inert carrier (so that the catalyst doesn't get dispersed in the liquid).

Try to coat pieces of broken pottery with finely divided silver (from the well- known reaction AgNO3 + NH3 + glucose, lots of recipes for this on the net), that is the standard catalyst for monopropellant rockets using H2O2.
Then secure the pieces to the opening of a narrow- mouthed aluminium bottle, fill it halfway full with atleast 70% conc. H2O2 without touching the catalyst.
When you lay the bottle flat, the H2O2 touches the catalyst and the rocket starts.
Make some kind of delayed tilting mechanism for the bottle on the vehicle.
When calculating the volume of produced gas, keep in mind that the water is also gaseous.
The heat of the reaction is enough to turn the entire liquid into steam.

I would be interested if your teacher is able to order high- conc H2O2.

I have produced about 3ml of 90%+ H2O2 about a year ago (by evaporating the water from 30% H2O2 in vacuum- works great, the water boils at 25- 30°C and the H2O2 at ca. 56°C when using an aspirator) and it is great fun to play with. When you soak a piece of wood with it and light it, it burns away rapidly with a yellow flame and hissing noise without making any smoke.

uber luminal - 9-11-2004 at 22:36

dry ice and an adjustable overflow valve.
once the pressure gets to whatever the valve is set for, it releases the pressure at a steady rate.

You could make one out of an old regulator something with the valve, just by adjusting the diaphram screws.

what are the reqs. for launching the car? can it be launched by another system (im guessing not, since that would be more of a mechanics feat than a chemical one)

vulture - 10-11-2004 at 12:16

Quote:

Then secure the pieces to the opening of a narrow- mouthed aluminium bottle, fill it halfway full with atleast 70% conc. H2O2 without touching the catalyst.

70% H2O2 is complete overkill and very dangerous. Remember, we're not trying to build a rocket that has to fight with gravity.

30% H2O2 will do just fine for propelling a small cart.

It doesn't have to be silver either. MnO2 on a carrier works too.

tom haggen - 10-11-2004 at 12:55

Could you just mill your own silver powder instead of trying to liberate it out of silver nitrate? Also what exactly happens when silver or manganese(II) oxide reacts with Conc. H2O2? I assume this is the type of reaction they use in a jet pack? I talked with polverone about this same topic and he said the exact same thing as you vulture. "Over kill."
I might try messing around with this type of reaction anyway since I have these types of reagents lying around. I have lab tomorrow, and I think I will have a much better idea of how I'm going to work this out. I starting to rule out using a high pressure stream of gas for propulsion, just because it seems impossible to accurately get a small vehicle to land on 25' with that method.

[Edited on 10-11-2004 by tom haggen]

garage chemist - 11-11-2004 at 09:37

Yes, now I also realised that 70% H2O2 may be the right concentration for monopropellant rockets, but totally unnecessary for the vehicle you want to build. Just experiment with 30% H2O2 (I have a feeling that the engine won't be easy to build- you need a narrow nozzle).

About the silver powder I don't know, but milling a metal is difficult.
Potassium permanganate is also a good catalyst, much better than MnO2, but when I used it to catalyse the decomposistion of H2O2, the violet colour disappeared.
I think some colourless manganese salts form, this also needs research.

Tacho - 11-11-2004 at 09:52

I would consider a reaction that take place inside a huge syringe. The plunger is pulled outward, lets say,15cm. Some gear system transform this 15cm in 25ft. That is about 50 times the original movement. You could get a rather precise stopping.

The plunger could pull a string winded (wound? sp? my english fails...) around a 4mm shaft coaxial to a 200mm wheel.

Can you built the car or its given to you?

The_Davster - 11-11-2004 at 10:21

The reaction of potassium permanganate and hydrogen peroxide is not catalytic. It is redox, the permanganate oxidizes the perxide to oxygen and water and the permanganate is reduced to manganese dioxide.

I tried this a while ago, if a solution of potassium permanganate was poured into DILUTE ( 35% peroxide causes the entire contents of beaker to eject

) peroxide quickly, there is gas given off and a brown precipitate is produced. I believe the ppt is MnO2 because it still has the ability to decompose peroxide. Hence why the permanganate solution must be poured into the peroxide quickly, otherwise the formed MnO2 will decompose the peroxide before it has a chance to react with the permanganate.

[Edited on 11-11-2004 by rogue chemist]

tom haggen - 11-11-2004 at 17:41

Ok I have some new information if anyone cares. I guess were not allowed to use a fuel cell or an electric cell. The guy in my group came up with this Idea that we should use some type of teeter totter thingy. This got me thinking if I could build a really small version of an old handcar maybe that might work. I'm attaching an image incase you don’t know what a hand car is. Anyway, my idea is to hook up a pressurized chamber to a hydraulic of some type with a hose. This hydraulic would need to do a specific task. The hydraulic will pressurize, that will make it extend when it’s fully extended it will depressurize and contract to its contracted position. Once it’s in a contracted position, it will pressurize and extend again. This will give a reciprocating motion. I'm thinking that this type of pneumatic cylinder is a lot like the one in a fully automatic paintball gun. If any of you think that this type of pneumatic cylinder sounds familiar let me know, I need to get one. All I would have to do is stick this reciprocating hydraulic under one handle of the railcar. This would mimic the man pumping the handle. Any advice would be greatly appreciated.

[Edited on 12-11-2004 by tom haggen]

[Edited on 12-11-2004 by tom haggen]

tom haggen - 11-11-2004 at 20:01

Edit: Image of hand car.

WRRWHC.jpg - 60kB

Tacho - 12-11-2004 at 02:29

Check the picture.

1- Inject water and lock that syringe.
2- Reaction push out the plunger of larger syringe, pulling the string.
3- String unrolls from shaft, moving the main wheel.
4-Plunger is stopped at the end of its course after having moved your cart 25 feet.

pressurecart.jpg - 12kB

tom haggen - 12-11-2004 at 09:35

Dude that seem like you would need a really large syringe or a very violent reaction. Though I really like the simplicity of the invention. I just remembered this morning apon waking up. When I took a crash corse electronics class at community college they had these automatic pnuematic cylinders hooked up to a relay ciruit and a source of pressure. I could use that exact same circuit to power my hand car idea, using my chemical reaction for my soucre of pressure. It seems overly complicated and probably is, and If it doesn't work I might revert to your invention tacho, because it makes a lot of sense. Don't know if it will go a full 25 feet.

Tacho - 12-11-2004 at 10:11

Quote:

Originally posted by tom haggen
Dude that seem like you would need a really large syringe or a very violent reaction.

I have a 60ml disposable syringe that looks perfect. I bought it in a veterinarian supply shop. Two of them connected like this...

......................water goes here, a T connection
..................................|
..................................V
.............________..||..________
|=====________===________=====|

...would give you about a foot of displacement.

Anyway, I have used a PVC pipe as a large syringe using a piece of rubber as the plunger top and a piece of thinner PVC pipe as the plunger itself. I used it as a pressure filtering system.

Quote:

Don't know if it will go a full 25 feet.

It will go any distance, it just depend on the plunger displacement and the wheel/shaft diameter ratio. If the ratio is too big, you will need more energy from the reaction to make it move, of course.

tom haggen - 12-11-2004 at 15:54

I think our group is going to try using your method tacho. Mine is way to over complicated. I think we are going to modify the outside diameter of our wheel in order to make the proper ratio for achieving the full 25 feet. Thanks for your help.

Tacho - 14-11-2004 at 04:12

Let me suggest that you make a small prototype first.

I have some experience in developing engineering projects, and small prototypes have saved me a lot of trouble before.

tom haggen - 14-11-2004 at 19:38

what do you mean make a small prototype? My class project is going to fit on a 6 inch plastic car. If that isn't a small prototype than I don't know what is.

Tacho - 15-11-2004 at 01:06

Sheesh!

Does it have to be that small? Those large syringes and main wheel just won't fit there.

Guess we're back to drawing board...

tom haggen - 15-11-2004 at 18:48

No I've figured out a good wheel to axle ratio. By the way where the hell did you come up with this idea? It's freakin brilliant. I just hope it's something my professor hasn't seen before, though I doubt it would matter.

Tacho - 16-11-2004 at 08:34

Thanks tom, I also think the idea is good, that's why I insisted on it. I hope it works. Please, post your results.

Magpie - 16-11-2004 at 11:43

Yes, Tacho, I think the wound string drive link with inherent limit is very clever.

I think I'm going to stop making comments about situations "going south." By the way is that expression reversed where you live?

tom haggen - 17-11-2004 at 01:25

Man, I just realized something. How are you suppose to get the liquid to flow down from the top syringe to the bottom syringe filled part way with baking soda? If you have the top syringe sealed off it wont allow fluid flow through the tube down to the lower syringe with the baking soda. Further more, if the fluid was able to make it down to the baking soda once the reaction pressurized it would send the fluid back up the hose preventing it from reacting further. Any solutions to this apparent design flaw?

Tacho - 17-11-2004 at 02:32

1- To start the reaction, I would leave some ammount of air along with the baking soda (or other fizzer), about 2 cc should be enough. This air will be compressed by incoming acid, allowing it to enter the main syringe.

2- After injecting the acid, the smaller syringe is then locked somehow. Insert it in a “restraining slot” carved in the cart, or drill a hole through its barrel and plunger (at the top) and insert a nail in it. The hole has to be drilled with the plunger pushed all way down, so the holes align when its content are fully injected.

Hole.......Hole
..|............|
..V...........V
.............________
|=====________=

Some other other possible flaws:
1- The hoses will escape due to pressure, and squeeze the fizzing sludge all over your teacher’s face. Not too bad, but may lower your grade. Make sure the hoses connections can withstand the pressure.

2- Your cart won’t stop at the end of 25 ft because the larger wheel has gained inertia and will stretch the string and compress the larger syringe, starting an oscillating movement. May not happen, just experiment will tell...

3- After your cart start moving, I believe it will keep moving, but starting it may be a problem. Again, only experiment will tell...

Edit: Magpie,

We don't have that expression, but you reminded me of a world map printed in Australia, where South was on top and north was at the bottom, but all the text was properly printed, so Australia was in the top and in the middle of the world! It's all a matter of references...

[Edited on 17-11-2004 by Tacho]

tom haggen - 17-11-2004 at 09:21

Apon dreaming about how shitty I might have done on my math test I came up with a much simpler method of injecting the acid. Dont even use a plunger on the top syringe. just get everything setup, and start pouring the acid in to the top syringe with out a plunger. Once the acid has met the base in the lower syringe and the reaction has commenced, cap the top syringe with a pressure tight seal. Pressure will begin building up and have no place to go, unless the lower syringe starts exdending. Im hoping when that happens it will pull more acid down from the top syringe, but experiment will give results. I'm not to worried about the whole inertia thing yet. I have to get it to move in the first place.

Geomancer - 17-11-2004 at 11:14

Well, you've lured me out of hiding. I should be doing important stuff for school, but instead... Anyhow, for a quick, practical solution I think you're on the right track. However, here are some other ideas for moving a device using a wholly contained chemical reaction. They are of varying applicability.

If one were to line a cylindrical can with a dense material, and then fill it half full with less dense solvent, the changing center of gravity as the liner dissolved should cause the thing to roll (the motive force is small, though). Variations are easy to come up with. If you want more power (who doesn't), have the device generate gas on the submerged portions. An inverse waterwheel inside the container would then provide the needed torque. You'd need a way to control pressure buildup. For greater simplicity, I'm pretty sure a properly constructed rubber cylinder half filled with hot water will roll, too.

Which brings us to the concept of using heat sensitive materials, rather than gas production. In particular, shape memory alloys provide a great way to turn heat into just about any mechanical phenomenon you want. If you have a supply of SMA, it could well outperform the piston approach. But It's gimmicky.

Back to using gas production, how about a reverse peristalic pump? Wrap a soft tube several times around a wheel (so the weight of the vehicle cuts of gas flow where the tube is squeezed between the wheel and the floor), and attach one end to a gas source, the other to a sink. In order for gas to flow from the source to the sink, the wheel must roll.

And then, of course, there's the "Cochlea". Take a soft tube and back it with a thin strip of steel (or whatever), forming a spring that will tend to roll up into a spiral. Starting out in a compact spiral, gas is produced, causing the tube to inflate and the device to uncurl to its full 25 foot length. So far you've only gotten the front part of the device to the finish line, but you've cleverly designed the reaction so as the gas is slowly absorbed, at which point the spring action causes it to roll up again, tail first. Of course, you could do a similar thing using SMA or even a bimetallic strip.

If it was my project, assuming the grade didn't depend on absolute success, I'd go with the Cochlea for the sake of novelty and elegance. Mechanicly stopped piston schemes are the route of least resistance, though.

tom haggen - 17-11-2004 at 12:13

The grade is not really about success, it's more about how well you do on your write up describing your processes, and calculations for designing your project. Of course, the thing has to at least work, but if it lands on 25 feet or not it not a big deal. I like your intresting suggestions geomancer. However, I have already decided to use the syringe method and unfortunately I have gone past the point of no return in this dirty whore of a college term.

[Edited on 17-11-2004 by tom haggen]

Geomancer - 17-11-2004 at 17:52

tom haggen: I figured as much; for the most part I posted my ideas just because I find them interesting.

Tacho: I have a map like that, but it's cut through the Pacific (I assume the one you mention cuts the Atlantic?) so that Australia is in the upper left, rather than the center. It's called the "What's Up: South!" map, apparently distributed by ODT, Inc (www.odt.org). I have a laminated copy on my wall, and it's a decent world map, except for the fact that there's some annoying information about various map projections on the bottom.

tom haggen - 3-12-2004 at 01:38

Well thanks to all that helped with the tips. Special thanks to tacho whos idea I ended up building off of. Here is the picture of my pressure cart. Solely built by my hands because the members in my group are mechanically retarted.
I've gotten the car to go a good ten feet. Tommorrow Im going to increase the diameter of the drive wheels as much as possible to reach the full 25 feet. The race is tomorrow wish me luck. I'll try to win this one for sciencemadness.

[Edited on 3-12-2004 by tom haggen]

3.JPG - 49kB

Tacho - 3-12-2004 at 02:08

Wow! That’s a beauty!
Congratulations! You have a future in engineering.
Tell the other members of your group to switch their major to literature.

Magpie - 3-12-2004 at 09:34

Tom that is wonderful! You should win on design and appearance alone. Let us know how this goes and what your propellant materials are. I would also like to know what other good designs were entered.

Don't be dismayed by having to do this all yourself. Just remember that those who do, learn.

tom haggen - 17-2-2009 at 12:27

Wow its been a long time, I dont know why I never reposted the results. My vehicle did not go very far only like 10 feet or so and I think it had to go 25 feet or something. If I remember correctly the person who won had a car that had a pressure chamber which was pressurized and then the car was set on the ground. After the car was set on the ground they had a release valve or something that spun a propeller that powered the car all the way to the finish line and won the race. I have since given up on chemcial engineering haha, my life has no direction now and I dont know what to go back to college for. On the brighter side, Im in recovery and i have 18 months of sobriety.

Man that was a cool car I had forgotten all about it untill I looked at this post and saw that picture just now.

[Edited on 17-2-2009 by tom haggen]

chief - 17-2-2009 at 12:57

If NH4NO3 reacts with K2CO3 and the "unstable" carbonate decomposes, why doesn't it work the same way with Na2CO3 ? I recall threads here where people made NaNO3 from hardware-store NH4NO3-fertilizer, and they were talking about boiling it quite extensively ..., nothing about a violent reaction ... ???

Sedit - 17-2-2009 at 13:09

Its a shame that I wasnt around for this threed back in the day. I was going to suggest and endothermic and an exothermic reaction powering a stirling engine. Im no engineer thats for damn sure but some one working in collage could figure out the energy required to go the distance I would assume.

Sucks to hear you lost the race man

Still a sweet little car you had there.

tom haggen - 18-2-2009 at 12:06

Its funny I stumbled on this post actually because other day I was at work day dreaming, and I started imagining a new concept engine. Basically what I was thinking of is designing an internal combustion engine that utilizies the detonation of a high explosive to expand the cylinder at a very fast rate which would result in a very radical amount of horse power. Yes you heard correctly, I'm wondering if there is a way to take the energy released from the detonation of an energetic material and convert it into mechanical energy. I just dont know if there is any material that you could make a chamber out of that would not deform from the shock of a detonation. Possibly titanium? and for fuel I was considering the detonation of nitromethane.

Sedit - 18-2-2009 at 12:40

Nitromethane is used mixed in engines all the time, I would think that what your suggesting would be more modification of the engine so that the seals and gaskets could take a higher amount of abuse without blowing out. Im sure if one looked into it you could find a mass of research done by people to improve the amount of nitro they could add to the mix without destroying there engine.

As for deforming, would there be a way to waste alot of the energy out of a seperate area as to govern the amount of stress put on the piston and cylinder? Like a relief valve of sorts would be the first thing that comes to mind.

tom haggen - 18-2-2009 at 12:49

the whole idea is to be able to convert all the energy from the explosion to mechanical energy. using a release valve to vent off extra pressure would be a waste of energy. Further more the type of engine im trying to conceptualize isn't your typical "alcohol" engine that runs on nitromethane. In an "alcohol" engine nitromethane is used in mixture with methonal, and these engines ignite a fuel air mixture which cause a small controlled "explosion" very similar to the way that standard gasoline engines work. The reason that "alcohol" engines have so much horse power is because a nitromethane/methonal mixture is a very volitile mixture and it burns much more efficently than standard gasoline or "petroleum" for you Euros out there. What im proposing is an engine that runs off the detonation of an engergetic material. It doesn't have to be nitromethane, it could be mercury fulminate for example. This is totally different from iginting a fuel air mixture in a starndard internal combustion engine.

[Edited on 18-2-2009 by tom haggen]

zephram - 3-3-2009 at 21:34

Probably to late to be useful now but looking back to the question that started this guanidine nitrate sprung to mind:

http://en.wikipedia.org/wiki/Guanidine_nitrate

not_important - 3-3-2009 at 23:26

If you look at the thermodynamics of engines, I think that you will find that there's very little difference between conventional fuel/air detonation systems and those using self-contained explosives. Increases in power output are obtained through higher temperature of combustion, and denser fuel/air mixtures. Remember air is ~4/5 N2, which contributes little outside of thermal expansion, certainly nothing to the energy content. Nitromethane provides more oxygen per volume than air, as does 'nitrous' - N2O having N:O ration of 2:1 compared to 4:1 for air.

Explosive fueled engines have been built in the past, going back to those using gunpowder. None ever proved practical or very efficient, a significant portion of the explosion energy is lost in none reversible processes.