High torque engines

Discussion in 'Boat Design' started by Boston, Apr 27, 2009.

  1. Rangerspeedboat
    Joined: Apr 2009
    Posts: 120
    Likes: 3, Points: 0, Legacy Rep: 17
    Location: Texas

    Rangerspeedboat Senior Member

    Being a steam fanatic on another forum, I can tell you alot about steam engines.

    First Stirling engines are known for high speed but no torque. There isnt any application for a stirling unless you want to run a small generator off of steam exhaust.

    A good triple expansion steam engine would probably supply enough power for what you want. A triple expansion engine would save steam and not sacrifice too much power.

    What kind of boiler were you thinking of using?

    I am very interested in this project.
     
  2. Boston

    Boston Previous Member

    http://www.boatdesign.net/forums/propulsion/these-turbine-alternaters-easy-make-26738-new-post.html

    hit the link above and you will see how I ended up at the conclusion that a pellet fired steam engine was pretty much the lowest cost and most environmentally friendly way to get from point a to point b and still be sipping a martini on a yacht

    been working out details and am at the boiler part of the problem. I had given double expanding steam engines some thought I had yet to find one in the size range I am looking for

    nice to have you drop by

    cheers
    B

    last page of that thread is a good summery of were things ended up so far

    nice idea about the steam exhaust
    would be a cool novelty piece in the engine room

    there is a particularly good explanation of these engines at http://www.google.com/url?sa=t&source=web&ct=res&cd=4&url=http%3A%2F%2Fwww.animatedengines.com%2Fvstirling.shtml&ei=BwD5SfyENMvJtgeWqoCfDw&rct=j&q=regenerator+stirling+engine&usg=AFQjCNFuy9YslDQQztfBFqDGMbE1V30Usw&sig2=NniTp--myDYv7Qa6yp9a-g
     
  3. TollyWally
    Joined: Mar 2005
    Posts: 774
    Likes: 26, Points: 0, Legacy Rep: 423
    Location: Fox Island

    TollyWally Senior Member

    Boston,
    LOL without looking it up, 16.97 or call it 17 in the field. Mr. Swanson was a genius.
     
    1 person likes this.
  4. Boston

    Boston Previous Member

    lmao
    I honestly thought I would stump the whole squad with that one
    thats pretty old school there mate
    Ill throw you a few points for that one
    no one actually knows how to use a square these days
    kinda went the way of slide rules

    cheers
    B


    in the 70s Ford made a 180 hp swashplate sterling engine as an experiment to replace some car engine
    it worked but they never did anything with it

    and there is a french submarine out there with a 1700 hp engine in it

    a normal flame will induce rpm of about 3000 in a small 100 Kw sterling engine
     
  5. imrankhaled
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: BANGLADESH

    imrankhaled Junior Member

    any body can say where can i find a 700hp diesel engine with suitable gearbox dxf drawing
     
  6. Boston

    Boston Previous Member

    and if you add up all those 6.7 billion anybodies you end up in the mess we're in now
    there is a brave new world outside the box and I say its a better world
    all one has to do is rub a few brain cells together
    my two cents
    (steps off off soap box and bows)
    B
     
  7. Boston

    Boston Previous Member

    Stirling Powered Ships

    the sterling engine seems best suited to electrical generation
    so one possibility is to go back to the electric engine powered rather than steam power system but replace batteries as a storage device
     
  8. Jimbo1490
    Joined: Jun 2005
    Posts: 785
    Likes: 41, Points: 28, Legacy Rep: 527
    Location: Orlando, FL

    Jimbo1490 Senior Member


    In terms of what??? There's NO WAY you're going to get lower BSFC numbers with steam than a modern diesel.
    BSFC is king because it means less fuel for more power, and also less CO2, soot, wasted btus per HP.

    Show me some numbers for BSFC that prove a steam setup is more efficient (and therefore environmentally friendly) than diesel.


    Jimbo
     
  9. Boston

    Boston Previous Member

    there are both calculations on this page and on the these turbine alternators are easy to make thread that clearly show the per penny cost of each btu is cheaper in wood pellet form than in diesel form

    the only remaining question is how to apply that cheaper btu to a drive system

    the external combustion engine
    IE
    steam
    or maybe the stirling engine
    being examples of external combustion

    as for carbon contribution
    as long as the source of the fuel being burned is grown harvested and used as fuel during the average life cycle of co2 in the atmosphere then the source is carbon neutral
    IE
    if a tree locks up x amount of co2 in its growth process over say fifty years
    and we harvest the tree for fuel
    and we know the basic co2 life span in the atmosphere is say 200 years
    then the net effect after the 51 or 52 years it takes us to cycle that carbon from atmosphere to plant to fuel to atmosphere to plant is net zero gain in atmospheric carbon
    thats carbon neutral

    where as if you burn oil that has been sequestered for millions of years adding billions of tons of co2 to the atmosphere that were not previously part of the typical cycle
    there is likely to be a dramatic rise in co2 in the atmosphere
    as we have had in since the start of the industrial age

    for god sakes man
    its a no brainer
    combustion of a renewable energy source rather than a fossil one is not the premise of the debate
    the question was at least
    how to best apply power from a low speed high torque engine to the water

    been answered
    ( thanks Rick for the help )

    now we have digress sufficiently that I thought I would start a new thread
    concerning this new engine consideration

    it is not necessary that a particular renewable energy be more efficient than fossil fuels
    its that the allure of the convenience be weighed against the detriment to the environment and the value of sacrificing some elements of that convenience for the benefit of our kids
    who will be having to deal with the mess we have made of things

    cheers
    B
     
  10. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 34, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Just a thought ..if you have all this torque applied to the prop will there not be an equal and opposite reaction causing the boat to lean??? With such a large craft you carnt just stand to one side of the helm to balance it !!
    Perhaps you need to build in a canted deck ..!!
     
  11. Boston

    Boston Previous Member

    its not that much torque that its a problem
    about 400+ ft/lbs at say 80 or 90 hp each engine and say 1000 rpm
    just enough to make a big slow prop work perfectly

    certainly not enough to transfer so much twist that it becomes an issue
     
  12. Jimbo1490
    Joined: Jun 2005
    Posts: 785
    Likes: 41, Points: 28, Legacy Rep: 527
    Location: Orlando, FL

    Jimbo1490 Senior Member

    Boston,

    Your explanation of how something is to be considered "carbon neural" is total mental ************, similar to purchasing carbon credits. CO2 lasts 5-10 years in the atmosphere, not more. That a fuel is cheaper is another point altogether; you can get lots of free wood, at least right now. But will you get more btuh per unit of soot/CO2 or any other efflux? No way, no how.

    Jimbo
     
  13. Boston

    Boston Previous Member

    looks like there are lots of similar explanations as to the definition of carbon neutral to me

    if you read through the thread you can clearly see that the fuel costs per btu have been calculated along with the various efficiencies of various ways of putting those btu's to use

    if you want to come back with an informed contrary argument feel free
    but the btu to steam % conversion in a domestic pellet boiler system is extraordinary
    with good pellet boilers running at an efficiency often in excess of 90%

    so it stands to reason that if I combine what amounts to a carbon neutral fuel source with one of the most efficient and simple methods of converting that fuel source to steam and running a steam engine that I would end up with the most btu cost effective and environmentally friendly ratio of btu/hp

    diesel on the other hand is in the ball park of 50~60% efficient

    from
    http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/diesel.html
    you then need to consider a transmission for diesel the where there need be none withe low rpm high torque reversible steam engine and the additional energy losses and costs associated
    and the expensive fuel tanks and delivery apparatus that can be replaced with simple and cheep hoppers for the pellets and Archimedes screw type delivery systems that are so cheep and easy to construct DIY

    you might also consider that all calculations were for a diesel cost of $3 per gallon and we both know thats only going up
    and a pellet cost of $225 per ton

    if you then also consider the chance of a boiler explosion ( although modern boilers are engineered to have a safety factor of 4 )
    you can maybe see how I then tried to apply a steam less heat engine to the exorcise

    you were doing so well Jim
    did you miss me over on the climate thread
    I kinda took a vacation from the efforts of so many, to convince so few, of the realities of what we have done to our climate
    even so
    lets keep the boating threads about boating
    and leave the climate argument to those who visit the climate thread

    if you want to argue the efficiency of an actual steam engine then you need to specify what type of engine with or without cogeneration
    the variations being anywhere from 1% to 90% efficient

    beautiful part being that there in a closed loop system not just water need be considered for the transfer medium

    and I havent even begun on that posibility yet
    and wont until I work out the sterling option
     
  14. Jimbo1490
    Joined: Jun 2005
    Posts: 785
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    But ultimately, BTUH is just the beginning of the food chain in a heat/expansion engine, because in the end, we want to spin a shaft to drive a propeller, right?

    Boilers may have great conversion efficiency, but unless you also want to make a bunch of hot water to heat a house or some such, the conversion efficiency to SHP is not going to be good. If it were all that, there would still be lots of steam piston engines around, despite all their other eccentricities.

    Whenever we see a modern steam powered something or other, it uses a turbine, because you can get good conversion to SHP. Of course the normal 'reaction' type of turbine (with little buckets or airfoils) is very difficult to manufacture.

    But there is another type of turbine that's fairly easy to build and has surprisingly high conversion efficiency. It was invented by Tesla and aptly named Tesla Turbine

    Now that would be a novel way to power your boat! Your project would make all the industry rags for sure!

    Jimbo
     

  15. Boston

    Boston Previous Member

    dam Jim thats a great idea
    let me see how its stacks up and if anyone still produces them

    low rpm and high torque is ideal for a transmission's system so if the turbine is ultra high rpm as most are then it will present practical difficulties

    although Im starting to lean back towards an electric engine running on a bank of Stirling generators
    simple and no boiling water and so 10% loss of energy just in the conversion process
    also I could run the Stirling generators directly to the electric motors with only a few batteries to buffer the load variations
    so Im almost back to were I started from with the electric instead of steam configuration
     
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