Solid fuel combustion engine?

  1. I was thinking.

    Now people plan to build factories to transform wood to liquid fuels.
    But why not run a motor on solid fuel.
    A diesel spread diesel to a fine particle dust so it burn faster and better.
    But you can get a explosion by sawdust.
    Is it not possible to get sawdust in to the motor?
    Does the exhaust from sawdust damage the motor?

    But is it possible to build a engine that don’t need a fast burning fuel?

    Lets say I take a gas tube and put in a sawdust burner with glow wire.
    I increase the pressure like in a engine and burn the sawdust.
    (The tube is heat isolated.)
    This increase the pressure and temperature.
    I now lead the pressure to a air engine.
    But I don’t want to let out hot air, so I have a chamber before air engine,
    were I spray in water that transform to steam and increase pressure and lower the temperature to 120-150 degrees.
    Now I build 6-8 similar tubes that in turn give pressure to the air engine with an automatic system that remove the ashes and load a tube with sawdust.
    The air motor is connected to a generator and a compressor to give pressure to the loading of the tube.

    Can I with this system get a working cheap effective engine system that need only solid fuel like saw dust and similar?

    Would it work?
    Could it get effective?
     
    Last edited: Sep 2, 2007
  2. jcsd
  3. DaveC426913

    DaveC426913 16,365
    Gold Member

    The shuttle boosters are solid fuel. They use ... um ... aluminum powder?
     
  4. Stirling engines operate on any heat source. In the 1920's they used wood, straw, etc. There's a company that makes a version that operates on the body heat of a cow.

    I understand some solid-fuel rockets use zinc powder and sulfur.

    Rail road steam engines used to operate on coal and wood.
     
  5. Explanation

    I will try to explane.

    A combustion engine need a fast exploding fuel so that the you get a total burn of the fuel when the piston is in its top position.

    A motor get to be very strong because of its many explosions / sec.

    But what if you build a motor that dont need to have a fuel explosion while the piston is in top position.

    Take a tube and fill it with compressed air and a fuel that burn slow like wood.
    The solid fuel will transform to heat and gas just like liquid fuel but take more time to burn.
    Then just lead pressure to a air motor.

    In this way it is possible to use solid fuel like wood and get a simpel engine.

    But it need some development to be used in a car. :)

    But would it work?
     
  6. It sounds to me something like Stevenson's steam engine. django
     
  7. It dont need to use any water as in a steam engine.
    I only burn wood in a tube that have a high pressure because things burn faster under high pressure.
    I dont need to have a fast combustion because i dont have a piston in the tube.
    When solid fuel has burned i lead the hot exhaust gas to a air motor.
    As i use a big combustion chamber i have much exhause gas to lead to the air motor and can stop the air motor by just turning a valve between combustion tube and air motor.
    A good thing is to isolate the tube because hot exhaust gas have higher pressure than if i let the heat leak out that will lower the pressure in the tube.

    I can have many combustion tubes that can burn fuel and take turn to produce exhaust gas to the air motor.

    Would it work?
     
  8. Astronuc

    Staff: Mentor

    I believe that combustion systems based on fuels like saw or coal dust use fluidized beds. It don't see that using powders in IC engines as being practical, since the dust/powder must be transferred pneumatically. The transfer system would be somewhat complicated compared to small diameter tubing for liquids.

    See -
    http://www.netl.doe.gov/technologie...ography/demonstration/aepg/baepgfb_mac4a.html

    Solid rockets use ammonium perchlorate, aluminum, iron oxide and binder.
    http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html
     
    Last edited: Sep 2, 2007
  9. Last edited: Sep 8, 2007
  10. brewnog

    brewnog 2,791
    Science Advisor
    Gold Member

    Yes it would work, but you get much more expansion (and work output) by using your burning wood to heat water, and using the resulting steam to drive a reciprocating steam engine, or turbine.
     
  11. LURCH

    LURCH 2,514
    Science Advisor

    Their have been similar attempts throughout recent history to use gunpowder as a solid fuel for ICEs (because of the enormous amount of energy density in gunpowder). The problem, as
    Astronuk mentioned, is mainly in the fuel delivery system. Trying to get a powdered or granular fuel into a cylinder and then seal it airtight, then exhaust the byproducts is a real nightmare. Of course, if you've got oil or some other liquid lubricant involved, your granular or powdered fuel is going to clump, specs of fuel want to wedge into the valve seals, etc.
     
  12. Yes I belive mythbusters tried many variations to this kind of engine and none of them could reload the combustion chamber fast enough.
     
  13. But with my system there is no piston that is moving and need a fast fuel burn.
    It can take its time and when fuel is burned it is released to the air engine.
    There you spray in water to lower the temp in the exhaust gas so that we do not let out exhaust gas with temp higher than about 120 degrees.
    So with big fuel chambers it does not need fast rpm.
    But if you want more power you can use ordinary fuels like petrol and any other liquid or gas fuel to get many work periods per second and then have a very efficient engine.

    English version of engine sketch

    http://picasaweb.google.com/magnus.ivarsson/EngEngine/photo#5113054754090447858
     
    Last edited: Sep 22, 2007
  14. Danger

    Danger 9,878
    Gold Member

    Hi, guys.
    I didn't weigh in on this before because I had nothing to say, but I just thought of something (actually 2 variations of something).
    These certainly wouldn't be practical, and the cost of 'fuel' would be horrendous, but I think that they might work as experimental or demonstration devices.
    I think that one could replace the head assembly of a 4-stroke cylinder with a custom unit attached to the 'muzzle' of a blank-firing machine gun. The complications are absolutely disgusting, though. To start with, the firing pin would have to be triggered by the piston position. I suppose that the stock camshaft could be used for that. I'm not going to bother trying to figure out the exhaust system right now. In any event, the engine would become a 2-stroke, since no intake or compression is needed.
    As an even less efficient variation, the gun itself could be attached to a crank so that the recoil could be harnessed.
    I guess that the bottom-line concept is that an encapsulated solid fuel might be more useful than trying to inject a loose form into the chamber.
    I know that it's not quite in keeping with your idea, Magi; just tossing out an idea that came to me.
     
  15. I love free ideas so feel free to write anything that comes in your mind.
    Thats what evolution is about. :)

    But I would like to get more comments on the construction of a
    motor with no pistons to think of because with no pistons the fuel burn can take its time.
    So any kind of fuels can be used and no exhaust gases will be let out
    with a temp over 120 degrees.

    What do you think of the construction.
    Could it be effective?

    http://picasaweb.google.com/magnus.ivarsson/EngEngine/photo#5113054754090447858

    I just like the idea.

    Regards Master of Science in Engineering Physics
     
  16. Danger

    Danger 9,878
    Gold Member

    Wow, you're a lot older than I thought. No offense intended; you just struck me as being more of a teenager or early 20's guy.
    That lastest art really helped me to understand what you have in mind. Thanks for the link. I have a problem with it, though (very minor); even with my reading glasses, I can't quite make out the label in the middle. 'Hot (?)' It's not really important, since the rest is clear enough.
    As for the design, I'm confused as to why you include a carbeurator on a solid-fuel combustor. They work only on liquid or gaseous fuels. A venturi might be able to suck in something like extremely fine-grained carbon, but no way can I see it working with sawdust.
    I'm also curious as to what you plan to use as an 'accumulator' to smooth out the delivery to the air motor.
     
  17. The carbeurator is there to use when using liquid or gas fuels.
    When using solid fuels there need to be a mechanical system to open and mount a wood pellet/saw dust or something similar.

    Use a browser were you can zoom in or load up the JPG to read it properly.
    The HOT is H2O.
    It is the water tank that is used to lower exhaust gas temp before ex.gas is released to exhaust pipe.

    The Air Engine can have a big flywheel to keep the rotation as in a simple engine.

    Is it interesting?

    A queestion.
    In a carbeurator you want to have a very fine petrol steam.
    Why are the petrol not heated to 50-100 C so that petrol steam is vaporised in to the engine?
    Is it to dangerous?
    Would it not produce more homogenous air-fuel mix?


    Magi
     
    Last edited: Sep 22, 2007
  18. Danger

    Danger 9,878
    Gold Member

    Yeah, it's interesting. :approve:
    In a lot of high performance applications, such as drag racing, the fuel supply is actually chilled. It gives a denser intake charge. Pre-heating it would detract from efficiency.
     
  19. Yes i know what a intercooler is. :)
    I am talking about boiling petrol and inject the petrol steam in to the cooled air
    to get the minimized dripplets of fuel in to the engine.
     
  20. Danger

    Danger 9,878
    Gold Member

    Actually, I wasn't referring to an intercooler. I've never heard of one of those being used on a normally-aspirated engine. What I'm talking about was called a 'cool can' in our slang; the proper term was 'fuel chiller'. The liquid-gas line (pre-carbeurator) passed through a cannister that would be filled with ice before the race.
     
  21. You talk about drag racing and getting most power from an engine.

    I talk about getting the best fuel burn in the engine and a
    compleate total burn of fuel to get a smal fuel per mile.
     
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