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My idea for a diesel-electric hybrid

  1. Dec 24, 2014 #1
    I've got an idea for a high performance Diesel, and I'd like to know if you guys think it's feasible, as me and my friend are mulling it over (be patient with me, I know I may not be explaining this properly).

    We plan to build a 24 cylinder engine, where the bore:stroke ratio is 5":4".

    The structure will be opposed-piston. Instead of a crankshaft, the piston rod will have a magnet attached to a spring (fully-extended length of 4") that is attached to the bottom end. The cylinder will be a solenoid. There will be 2.71 cubic inches separating the pistons from each other when both are at TDC, which will allow for a 30:1 CR.

    The reciprocating motion of the pistons will be translated into electricity via the magnet oscillating inside the cylinder. The AC electricity will be rectified into DC, and stored in a battery, which will power electric motors on each wheel, as well as other necessary electronics. The lower reciprocating mass will also allow for higher RPMs (well, not really revolutions...).

    The valves will be electronically-actuated, since there's no crankshaft to do valve timing, which will also allow for a square valve timing profile. The engine will have six strokes:

    First stroke: air intake
    Second stroke: compression
    Third stroke: fuel injection
    Fourth stroke: exhaust of combustion products
    Fifth stroke: injection of demineralized water
    Sixth stroke: exhaust of steam

    The injection of demineralized water will cool the engine via evaporative cooling, rejecting heat to the exhaust, which will also exert a force on the pistons, for an extra power stroke. So this engine will produce power once every three revolutions. Also, the steam will dilute the emissions, which will reduce or eliminate the need for an SCR system, and also decrease brake specific fuel consumption. The engine will need to use steam cylinder oil, as that will resist the washing action of the steam.

    The engine will be fitted with a variable geometry turbocharger, particulate filter, and a selective catalytic reduction system.

    The engine block will have an ammonia refrigeration circuit, which will be controlled by the exhaust gas temperature. If the exhaust gas temperature rises above 900C, the refrigeration circuit will turn on, and stay on until it falls below 900C.

    By using electric motors to drive the wheels, the efficiency will be improved, and it will have a smooth torque curve, which eliminates the need for a transmission, reducing weight, and regenerative braking can be done.

    What do you think?
     
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  3. Dec 24, 2014 #2

    Doug Huffman

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    Too expensive, too complicated, too little improvement. My 12 y.o. ALH TDI still reliably produces 50+ mpg, 200 passenger-mpg.
     
  4. Dec 24, 2014 #3
    I'm trying to get best performance, not necessarily the best mileage. A diesel-electric can produce torque at 0 rpm, with a flat torque curve. This allows for excellent acceleration from a standing stop, and having independent electric motors on each wheel allows for torque vectoring, which will improve handling.
     
  5. Dec 24, 2014 #4

    Doug Huffman

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    Argumentative ad-hockery.
     
    Last edited: Dec 24, 2014
  6. Dec 24, 2014 #5
    I asked a question, and I expect a more thorough answer than "it's too expensive".
     
  7. Dec 24, 2014 #6
    I was asking, is this feasible, not necessarily economically feasible. What information do you need?
     
  8. Dec 24, 2014 #7

    462chevelle

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    First off, the camshaft is what actuates valves, not the crankshaft. You have to keep things simple because there are to many things that can fail. Just imagine you build such an engine. How many valves will it have with that many cylinders, how many valves per cylinder (usually 4/cyl) on a diesel. Think about how much electrical energy they will use, and if one fails, then what. He isn't being rude or anything counterproductive, your idea is a little theoretical since no one in their right mind would invest, which hardly gives it a place in an auto engineering section.
     
  9. Dec 25, 2014 #8

    Ranger Mike

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    Welcome and looks like you put a lot of thought into this. Lets look at the parts that I know about from a manufacturing point of view and compare it to a small block V8 that has proven it self a winner in every competition since its introduction in 1955.
    a 24 slug engine gonna be one large, heavy package. It will take a large chassis to house this and then add the transmission and associated suspension components..much engineering, a lot of frontal area, aero drag, weight..not gonna be a performance race vehicle.

    In racing I have found any time you use springs for anything you are asking for trouble. Now add a 4 inch spring and add a magnet and I think the failure rate will be very high.
    I wish we could find solenoids to actuate valves RELIABLY because this is just not the case today. We are back to the valve spring thing and eventual soft spring rates and collapse or failure.
    The piston required to have 30 to 1 compression ration is not going to be a high rev deal nor is the con rod. Rotating and reciprocating weight is way up on the weight scale as is the engine block with almost 3 inch wall separation..very heavy.
    You have magnets moving linearly in the cylinders to generate electricity so what kind of wire will have flex life capable of these oscillations. Otis Elevator Company did a life test one time to make its special bend radius wire. This wire is NOT cheap.
    Even if you get the AC current to the rectifier you have a huge amount of weight added with the rectifiers and storage battery and we have not even begun to talk about the
    entire water injection of demineralized water will cool the engine via evaporative cooling
    You will have one heavy beast when you have to carry water on board let alone the special demineralized water. Where you gonna go to fill it up? Wal-Mart?
    The purpose of this contraption is to “
    power electric motors on each wheel, as well as other necessary electronics. The lower reciprocating mass will also allow for higher RPMs (well, not really revolutions...).”

    I am not even gonna address this last garbled comment on RPM.

    The rest of the concept of variable geometry turbocharger, particulate filter, and a selective catalytic reduction system, ammonia refrigeration circuit add very high costs, too much additional weight with very little benefit. The elimination of the transmission to save weight is dubious at best.

    Production costs compared to current automobile offerings is excessive, the vehicle weight and frontal area are prohibitive. Performance compared to typical production offering are lacking and headache of ownership and maintenance are not worth the extra cost.
    I for one am not gonna spend a lot of time planning my trip around the closets demineralized water supply house and until the magnet spring thing is life cycle tested, no way am I driving the thing. The current crop of IC engines offer les emissions at idle than a human jogging. Petroleum oil is king and will be for DECADES. Oil is awesome and provides cheap energy and will for centuries to come.
    Thank you for taking time to post and wish you happy Holiday.
     
  10. Dec 25, 2014 #9

    Doug Huffman

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    In a decade, the Eighties, of racing F-Vee and SCCA B-Sedan Datsun 510 (the 510 was invited to the Run-offs), I don't recall ever breaking a valve spring. Lots of other stuff, $85K in broken parts alone, but not springs. In my career I directed testing of nuclear reactor SCRAM springs with never a bad reading let alone a failure.

    Broken springs are due to poor design or application.
     
  11. Dec 25, 2014 #10

    Ranger Mike

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    Doug
    good points all..
    i been lucky at Mid Ohio with the valve springs but remember that on Road Course you do not have constant HI RPM situation like in round track racing. In fact very little long term hi RPM. Not so much on the short track ovals where you lock into high gear and race it between 3500 and 8500 RPM lap after lap. Sustained high RPM racing means the first thing to go is valve spring tension. You must have have proper top end oiling to cool the springs. Drag racing takes a toll on top end as well so to maintain a proper spring rate is important.

    Merry Christmas fellow racer
     
    Last edited: Dec 25, 2014
  12. Dec 26, 2014 #11

    SteamKing

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    Just arbitrarily picking a CR for your diesel design is not recommended. The late Olds automotive diesel had a CR of 22.5:1 IIRC and it used cylinder bores much smaller than 5".

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

    Even though diesel engines are compression ignition, diesel fuel is still subject to pre-ignition if the engine is not correctly designed. Large bore industrial diesel engines use CRs on the order of about 16:1 or less, and the CR drops as the bore dimension increases.

    24 cylinders, even in an OP arrangement, makes for a physically large engine. Large engines imply heavy weight.
    You don't need a 30 liter diesel engine for most automotive applications, even for a large tractor truck.
     
  13. Dec 26, 2014 #12

    Doug Huffman

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  14. Dec 26, 2014 #13

    SteamKing

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    We had a F-M OP as a back up generator on our ship as well, a C-4 built in the early 60's. We lost one of our SS-TGs while in Africa, and we had to start up this beast to maintain electrical power in the ship. In addition to being quite noisy while running, the F-M raised the engine room temp. from about 100 F to 110 F all by itself, which made working conditions rather unpleasant.

    Also, the silencers from these engines can be located in the stacks, rather than adjacent to the engine itself.
     
  15. Dec 26, 2014 #14

    Evo

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    It appears the OP has abandoned this thread, they have been online in PF but have chosen not to respond to this thread. Sorry for everyone's hard work and attempts to help.
     
  16. Dec 27, 2014 #15
    I'm back here. I had some stuff to do over the past few days.

    We're going over my idea with my automotive engineer friend. He says it could work, but we'd have to worry about corrosion and ensure the water is nearly 100C to ensure it actually vaporizes and doesn't just heat up and flood the cylinder.

    We've also changed the bore:stroke to be 100 mm:105 mm, and we plan to use aluminum foam cased with a thin layer of solid aluminum to save weight.
     
    Last edited by a moderator: Dec 27, 2014
  17. Dec 27, 2014 #16

    Bystander

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    Can you go through this in a little more detail? For instance what energy source is moving the piston(s) for each step?
     
  18. Dec 27, 2014 #17
    You don't know how an ICE works? third stroke and fifth stroke are from combusted fuel and vaporizing water, respectively, the others are from inertia.
     
  19. Dec 27, 2014 #18

    Bystander

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    What inertia?
     
  20. Dec 27, 2014 #19
    The inertia from the power strokes and the flywheel 9or in this case, the springs).
     
  21. Dec 27, 2014 #20
    Bystander makes a cogent point; with nowhere to put a flywheel and each cylinder mechanically separated, the only thing keeping a piston moving is its own inertia, so they'd need to be very heavy to oscillate while creating high pressure at the end of their stroke. Also starting it would be... interesting? I suppose you could run the solenoid in reverse and attempt to fire the piston upwards with enough force to achieve 30-1 compression, but since coilguns are inefficient as hell and you'd probably be attempting something on the order of thousands of g's of acceleration I'd wager your solenoid would just explode. Plus you'd need one mother of a capacitor bank to jolt it.

    OTOH it might be educational to watch a machine explode due to lorentz forces, fuel air combustion, steam expansion, and high temperature arcing all at once.
     
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