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Diesel Electric Propulsion

Discussion in 'Technical Discussion' started by Crewagency, Nov 26, 2004.

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  1. karo1776

    karo1776 Senior Member

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    OK how this works is the water is directly injected into the expansion space formed by the piston and cylinder. Almost like a high pressure modern diesel direct injection system... actually operates at similar pressures of around 7000 Bar. The water flashes to steam on impact with a hard surface in the cylinder, cylinder head or piston crown made of something like polycrystalline diamond. Therefore, the steam is produced on injection of the water steam.

    The issue is the pumps that produce the pressure put the energy into the water in compression like any hydraulic fluid... and this is little different from heating water to create steam... but it is heat energy (powering pumps though creation of either the electrical or mechanical energy) that is converted to hydraulic energy as both pressure and flow.

    So just guessing without doing a very complex energy balance its not much better than heating the water and creating steam in the first place... likely worse:
    This means less energy efficient or higher ultimate entropy of the whole system. Why is all the energy change interfaces chemical > heat > kinetic (steam) > electric > Kinetic (hydraulic) > heat > kinetic (steam) > kinetic (mechanical). At every stage of interface or change from one form to another there is energy that cannot be tapped and turned into useful work in the exchange (entropy)... but there are two phase changes both taking place in the piston cylinder water to steam and then back steam to water.

    See on a steam engine it works boiler chemical > heat > kinetic (steam) > (kinetic) mechanical. There are two phase changes first water to steam and then steam to water.

    Therefore, in the lab if the energy comes from the electric power company to the water or give it hydraulic energy is free it really works but put it in a closed cycle and I doubt it adds up any better than a conventional boiler supplied steam system.... just a bunch of different equipment... all just to not have to have a boiler???
  2. Marmot

    Marmot Senior Member

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    It would be difficult to get further off base than that. Read the articles before commenting.


    I don't think there enough smileys to go around.
  3. Opcn

    Opcn Senior Member

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    Karo, you seem to be discussing the Crower six-stroke engine. The link Marmot posted is about using an injector system to convert water to steam without an external heat source. It seems to me that powering the injectors would take more energy than you could possibly capture from the steam, but that pessimism of mine is why I'm missing out on this fabulous investment strategy. I didn't make money off oc Madoff either, I'm such a fool...
  4. karo1776

    karo1776 Senior Member

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    I did read the article... It was just you were lured in... ! And, I know more than you do... haw haw!

    These guys are squirting a stream of water into heated chamber connected to the inlet of the steam reciprocating engine.. which then transfers the steam into the expansion chamber... BUT THAT was done in the 18th century its called a BASIC STEAM ENGINE.... actually it was done in ancient times.

    But that is not the point or idea of the technology and disregarding its practicality... here with these guys in that article...because they are experimenting in a lab the steam generator is external to the engine and basically is a mini boiler... and need the valve between it and the engine for the engine to run in a controlled manner.

    The technical goal they are striving for is to create the steam directly from the stream of water... right now it is a stunt because they have to use boiler to actually accomplish it... in a usable manner to demonstrate an engine running.... it is just they are using higher pressure injection of the makeup water... IT DOES NOT WORK as intended... now.

    SO it was obvious to every real engineer seeing the thing the idea, it need extra heat to accomplish the flash to steam making it a stunt.

    What the article and you may not know someone else had already did that a long time ago, have already put the thing directly into the engine... without the external boiler. Why is because the mechanical functional problem of having as constant stream of water producing the steam in the external "steam creation chamber... i.e. steam generator..." needs to to have a inlet metering device (i.e. like all reciprocating steam engines needing inlet valve system). And, the heated container essentially acts like a boiler... . But with the timed system the steam of water is injected directly into a heated pre-chamber like component internal to the engine or the actual expansion chamber of the basic piston engine eliminating the steam control valving to created pulses of steam to run the engine. Don't know if it really worked or not!

    And, it is obvious to engineers seeing this technology or hearing about it... and if it practically worked as stated then the stream of water produced steam could be used internally to an engine where it would be injected to produce the steam a timed pulse width modified metering scheme to control speed and output of the engineer. I believe is the real intent of where the technology is going.

    But what you don't know... from this article as it is not up to date on the technology and concepts...

    Having been an engineer I have a lot of colleagues and friends who get called into look at these types of things... for various reasons. It provides us with long conversations of companionships about this or that... so what you don't know is:

    A couple engineers I know looked over these technologies some time ago... and... it was obvious to everyone it was a joke in the form described in this article... as that was a stunt. Sort of like a hopeful inventor applying some applied research to an ancient technology to make it some grand invention that will make him rich and buy a big yacht and house on the Riviera retirement.

    But everyone thought it was best applied as an internal injection of a timed and injection into the engine directly to internally produce the steam. If the stream of high pressure water could practically produce the steam outside of laboratory conditions in a manner of usable practical quantities. So I don't even see an invention as it was obvious to anyone skilled in the art, once the old idea of producing steam from a steam of water by impact... (experiments on that have gone back to the 19th century). Anyway, last I heard that is where it was going... the timed injection and creating the steam internally to the engine rather than this updated but conventional steam engine technology of the 19th century.

    Sorry... I added to the information of the article... I would not invest much in this... and certainly not real money!

    So I ask you what's the "gros bordel putain de merde" difference?
    (no in French that does not mean a "big bordello of whore dung"... meaning more like "big god darned mess").
  5. Marmot

    Marmot Senior Member

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    Why do I suspect you have never had anything to do with steam beyond watching a tea kettle boil?

    Substitute the line of smileys with "roll eyes." Call me arrogant if you wish but this crusty old steam chief engineer feels like it is deja vu all over again listening to a bunch of first year cadets telling each other how they will reinvent the marine propulsion business.
  6. karo1776

    karo1776 Senior Member

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    Marmot, I was giving you a hard time as crusty old steam chief engineers see thought these things... and I truly think you were pulling everyone's leg posting the article... and keeping me in line from posting too much dream technology... as I am a geek extreme sometimes!

    But coincidentally some time ago I had talked with some old engineering friends who had looked it over... and therefore knew more than the article on the "pressurized water to steam cycle... ???".

    I think why these thermal machine entrepreneurs are so prevalent is that there is just such a huge market worldwide, and when you do the numbers any true success equals big numbers. But as you know most of it is as I said in French... . It's just real hard to beat a diesel or even for large ships turbine or steam plants... they have mountains of experience and development and improvement behind them.

    I post these engineer dream concepts as it is a forum for that and imagining what might be... but when it comes down to the nitty gritty an owner will usually not take risks on them unless he is foolish and knows no better, perhaps like this guy, warning watch only if you can resist "breaking out the grease bucket and initiating him to engineering":

    The Fendi Princess Yacht ft Prince Albert II at the Monaco Yacht Show 2011 | FashionTV - FTV - YouTube
    and/or
    "Carpe Diem" Yacht Decked in Bulgari ft Prince Marcus, Monaco Yacht Show 2011 | FashionTV - FTV - YouTube


    The submarine stuff is real but hugely expensive and only perhaps applicable to as a hobby figment of imagination to yachts. Hybrid yachts are the same in many respects, and I think a phenomena of the hybrid car craze.

    The real driver for the owner is quiet reliability. That term "quiet reliability" is exactly the driver for yacht propulsion and generating plants. This is why Feadship is so successful. The technical aspects have been sorted and refined... so the owners can play with all the show and not worry about the go aspects. After all the sea can be both a playground and a very unforgiving place. So taking risk may not only ruin a vacation but might result in loss of life.

    As you know, the owner does not like problems during his relaxation time on the yacht. So these lets call them emerging technologies all become problematic when applied as the power plant of an at sea palace. The fuel cost issue is not a reason for yachts to go after the last drop of efficiency, if one can spend 25 million whatever on a 40m yacht and 3 million and more a year supporting it... the cost of fuel is not a real concern. Yachts are not commercial carriers or transport shipping companies.

    The reason, I think, diesel electric propulsion is attractive is that it goes back to the early days of power boats; it can be very quiet and reliable, and; it provides for the potential of reduced maintenance, service and down time costs. Also, it can provide with other proven technologies at anchor stabilization; station keeping, and; improved maneuverability in tight spots... all of which can be important.

    But applying it to yachts under 60-65m is a technical challenge. The issues are mass, volume and complexity. Not presently possible on anything other than a displacement boat. I cannot afford a 65m plus yacht but recognize diesel electric would be very beneficial to that "quiet reliability"... and wonder if I would be truly happy with such an animal.

    But back to the YouTubes... even that guy is ultimately interested if he buys a yacht in "quiet reliability".
  7. Marmot

    Marmot Senior Member

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    Now that earns a respectful smiley for sure :) and a big grin to boot :D
  8. karo1776

    karo1776 Senior Member

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    Actually have seen that run... the Crower!

    Your assessment is correct on the water injector steam cycle... or the concept of using pressurized water to impact on something hard and "flash to steam"... almost like perpetual motion machines... and I actually know people who invested in those type of things... and it just blows me away how they got money in the first place to invest! But look at Madoff...

    "sucker born every minute..." or as

    W.C. Fields said,
    "Never give a sucker an even break or smarten up a chump."

    or the old saying,
    "You can't cheat an honest man."

    And, my favorite from... Senator William Andrews Clark... the reason behind the 17th Amendment of the United States, saying when accused of buying the entire Montana legislature:
    "I never bought a man who wasn't for sale"
  9. HTMO9

    HTMO9 Senior Member

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    As perfectly stated before, there is no free lunch or more academically spoken the Perpetuum Mobile will never come. Until somebody invents the Flux compensator or finds these famous Delithium Cristals, we have to live with what we have.

    As long as the electricity tank does not excists (which will may happen some day), we have to rely on fossil or alternative (green) fuels. I do not believe, that we should take the food of humans and animals and convert it (in larger scale) into fuel for cars and planes (or yachts?). The name of the game should be increasing the overall efficiency of thermo dynamic machinery and this in a manner in order to produce the absolut least amount of exhaust gases.

    The best way of saving energy is to use as little as possible of it. The automotive industry has achieved milestones in energy savings, which would be believed imposible years ago. 50 miles per gallon was best possible some 30 to 40 years ago. Now Volkswagen will bring a car into production which is suppost to achieve 235 miles per gallon.

    No matter what kind of combustion or energy conversion (Flux converter:)) will be used (reciprocating piston engines, rotary piston engines, steam engines, turbines, hybrid propulsion, diesel or petrol, fuel cells or whatever) it will leave some products of its fuel or propellant behind.

    Looking at our subject, the propulsion of ships and yachts, we are faced with new standards of pollution control. IMO Tier II is in effect, IMO Tier III is in the near future, Tier IV will follow. As IMO (Marpol) Tier III can still be managed by applying modern technology within the engine, Tier IV will definately ask for external exhaust gas cleaning. In commercial shipping we are lucky to have cathedral sized engine rooms which are capable of containing large exhaust gas cleaning devices like heated particle filters and catalytic converters, scrubbers, afterburning turbines or selective exhaust gas recycling. But yachts or boats will not have that luxury of space in the engine room.

    The only way for smaller engines to comply with more and more restrictive pollution laws is to use cleaner fuel. Dirty Heavy Fuel Oil or high sulfur fuel oil will not be possible in the future any more. But even almost sulfur free automotive diesel will reach its limit one day.

    One answer IMO could be the use of GTL (gas to liquid) fuel. GTL diesel fuel is produced from Natural Gas via the Fischer-Tropsch-Synthese or the High Temperature Reactor process. It is the cleanest carbon hydrogen based liquid fuel available. It does not contain any sulfur, no molecular nitrogen and most important no aromatic carbon hydrogen molecules like parafin or others. And it does not require larger modifications on excisting diesel engines.

    Intensive tests of the Mercedes company on a unmodified diesel car has found a average 12 % reduction on fuel consumption and a up to 30 % reduction in some exhaust gases. In combination with urea injection (reduction of NOx) it was the cleanest possible combustion process possible.

    The break even point for production was at an cruide oil price of 25 $ / barrel.

    Several refineries are producing GTL at the moment (Malesya, Katar, Sweden and South Africa). Russia is building several plants at the moment. As we have cruide oil for maybe 100 or 150 years left, natural gas will last for 300 to 500 years to come.

    Boating will be possible even in the far future, but sorry, without the belching black smoke.:D

    The perpetuum mobile !???

    Attached Files:

  10. brian eiland

    brian eiland Senior Member

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    Sorry many could not access this article. Seems as though ProBoat has made it a bit more difficult to download their articles. But here was one review I thought was well done.

  11. brian eiland

    brian eiland Senior Member

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    Letter to the Editor (Nigel Calder author)

    I read that article with great interest as well, but I think I need to reread it several times over, as I am 'electrically challenged'
    I just wrote this 'letter to the editor' that will hopefully reach Nigel Calder.

    Nigel Calder
    Professional Boatbuilder Magazine

    Dear Nigel Calder,
    I've been following this diesel-electric technology development since David Tether began his work down in Solomon Island, MD,....the 'electric wheel' I think it was referred to originally. I have also followed, and participated in, some of the fairly extensive discussions that have been posted at least 4 of the boating forums.

    From all of the documentation I have collocated and saved, I find your writing on the subject the most trustworthy in my opinion. I particularly value your series of articles that have appeared in Professional Boatbuilder magazine.

    I just finished reading your latest article in ProBoat #142, “The Hybrid Conundrum”. I must admit that I am a little confused, and a little disappointed that this diesel-electric technology has NOT worked out to be a much more positive technology for the pleasure boater. I was sure hoping it would live up to the much vaulted hype it had originally espoused. My compliments to you for not getting trapped by the 'hype', but rather treating the subject in a very professional manner.

    I do have a couple of questions for you though,...and please realize these are coming from a guy who is real 'challenged' with the subject of electrics. :)

    1) Contained in that latest article from ProBoat, you post a photo along with this description, “BluWav Systems was the most efficient large electric-propulsion motor tested by the author. The motor controller, which supplies three-phase AC power from a DC input, is at the top of the photo.” Are you saying that the AC motor(s) are the most efficient and should be utilized in these DE systems? Are you saying that DC sources (either stored and/or from a DC gen-set) are converted into AC by the motor controller to power up the AC motor??

    2) Correct me where I am mistaken, but wasn't one of the real attractive features of these 'modern' DE systems the fact that simpler permanent-magnet DC motors would be utilized? ….or even a more unconventional DC motor configuration such as these recent rim-driven propellers.
    I was already anticipating the development of these rim-drive propulsion units for my gamefishing catamaran design,....retractable drives as well. Retractable rim-drive on catamaran.

    3) Was my interpretation that the use of DC verse AC components in these 'modern' DE systems was advantageous such that the DC generating set could be allowed to operate at a variety of RPM's and output levels, depending upon the slow or fast speed needs of the DC motor units it was powering? In other words the DC gen-set would not have to be operated at full speed all of the time, as do the AC gen-sets need to in order to product that proper AC wave form?

    My thoughts and hopes here were that the DC gen-sets would be more adaptable at supplying the propulsion motor's and the ship system's requirements. ....And maybe even without the ship needing a big storage bank of DC power? Wasn't that the goal that Glacier Bay's OSSA system was pursuing?....a closer match between the DC power being produced vs the DC power needed at any particular time??

    4) I had in mind another DE application aboard this 'New Age Trawler/Explorer' vessel with gamefishing/diving/survey capabilities. It was to be a smaller version of the Humphrey's 40M SkySail Motor Yacht
    New Age Trawler/Motorsailer, Kite-Assisted Power Yacht

    “The power would be a single main engine sized to develop the vessel’s desired top speed, and it could transmit this power by conventional shaft/prop arrangement, or with a Volvo IPS dual prop unit, or via a retractable azimuthing Rim-Drive prop unit.

    Supplementing this single main engine would be a single DC diesel/electric power unit to provide for:
    1) Ships electrical requirements
    2) Slow speed operation by electric (wing) motor belted to main prop shaft for docking, trolling, etc
    3) Maneuvering bow and/or stern side thrusters

    The entire ship would be powered by only two diesel engines, basically sized to provide:
    1) Full main diesel power, unimpeded by interceding diesel/electric conversion
    2) Slow speed operation and ship’s systems via the smaller diesel/electric unit
    3) ‘Twin power’ emergency backup as either engine can run all gear”


    This is still a very viable configuration, is that correct??

    BrianEiland
    RunningTideYachts
  12. karo1776

    karo1776 Senior Member

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    Brian, maybe I can provide some insights. I did my graduate paper in electrical engineering on hybrid power systems... now longer ago than many of the forum member are old. Mostly it concerned automotive uses but also considered trucks and yachts... why yachts is I been interested in boats from an early age.

    The answers to your questions are the same today as they were 40 years ago.
    Question 1:
    Most practical electrical machines which are driven by a rotating power source. It is simply that fundamental motors and generators which rotate to create or use electricity are AC machines. That is fundamental as magnets have opposite poles N and S whether the magnet is permeant or electrically created. As the alternate magnetic fields of the N and S poles cross winding and created current and voltage the direction of these currents and voltages are opposite.

    Magnetic forces

    DC is only able to be produced by switching the leads from the windings of the motor... mechanical or electronic commutation. So the basic permanent magnet machines are fundamentally AC and the DC is produced outside that at a cost to the efficiency as there are electrical losses in converting it whether that is in the loss of the commentator and brushes not being perfect for a given speed and the mechanical losses... but also for the more efficient electronic switching. And, any subsequent conversion is burdened with losses but in modern systems these are very low.

    Batteries produce and absorb only DC and the charge discharge cycle are not nearly as efficient... as you also have to change chemical energy to electrical or the reverse. Charging batteries is much more inefficient than converting between AC and DC and back.

    So you see if you have any system the most efficient production by generators is AC and the most efficient use is AC also in the motors.
    BUT
    If you have batteries which are only DC devices in the system a conversion is necessary with an attached inefficiency of conversion from AC to DC and back.

    Question 2: Partly this is answered in the answer to question 1. Your premise is incorrect thinking DC is simpler and more efficient than AC.

    But the question is tied to the comment as to the attractiveness of the ring drive propulsion motor/propeller combination. These are rotating field machines where the rotating field or magnetic drive force is created in the stator or the rim of the machine... each coil turned on and off electronically to create a moving or rotating magnetic force to drive the rotor/propeller. So they are electronically commutated. Therefore they do not have brushes. How the stator winding is connected determines the output characteristics of the motor.
    Now this is where you can really get confused.
    The rotor which is part of the propeller could either be PM (permanent magnets) or a squirrel cage type electro magnet EM. In the squirrel cage EM rotating field of the stator induces current flow in the coils of the rotor which
    are part of the rotor/propeller which oppose the magnetic fields in the stator as it rotates this creates a force which drives the rotor/propeller. You could use PM too.
    The problem is for rim drive is that basic electric machines have the efficiency directly tied to "flux density". A very large generator or motor high very high flux density because it has a lot of magnetic force confined in a smaller volume than a small machine.... why is lots of conductors or very large magnates creating intense magnetic forces in a relatively small volume of interface... small machines struggle to get high flux densities. This means large machines are more efficient than small machines. And, conversely high current flow improves this meaning two things running it at the low range of its capacity lowers its flux density, and also small conductors with high current flows are more efficient... but heat up quicker. All this means the technical challenge for ring drive propellers is to create high flux densities in the drives electrical components which are spread out in an basically inefficient manner.

    Question 3:
    The most efficient system is AC but you don't have to run the generators at any particular speed and simply generate what is called wild frequency and wild voltage AC. Meaning you get what you get from the speed of the diesel driving it. Yes the PM machines are more efficient. Then simply use a modern electronic motor variable speed AC controller to drive the propulsion and various auxiliaries at whatever speeds they need to be driven. These are very efficient at taking whatever input within the design range and outputting whatever is needed within the output design range. This is the most efficient system electrically. But add in batteries and you just added relatively large efficiencies... unless you have other operational situation or design limitations where it is better to store the overage produced... like using standard generator sets in the system which put out controlled voltage and frequency.

    Question comment 4... no comment.
  13. karo1776

    karo1776 Senior Member

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    Brian, the yacht Ambrose III is powered much as you suggest... two main engine generators powering electrically driven asipods.

    Couple further comments more electrical equipment of the motor and generator variety are most efficient when operated at or near full load. Why is that is the design point and where the most flux density is present in the machine.

    Some designs or configurations which have not been considered, noting these are only related to the electrical plant:

    First is use of an induction generator... that is basically a squirrel cage type AC motor used as a generator. Now this seems strange and will not work unless the motor being used as a generator is "excited" or connected to a power grid which already has power. Why is that it has no magnetic field to induce current flow in the output coils so running it will produce nothing, actually very little as there is some residual magnetism in the squirrel cage pole pieces. It works as a generator is only possible on a yacht by having it feed a main power grid which is connected to the ships service generator... whereupon the electric motor works as a generator only when the drive engine speed exceeds the synchronous operation of the motor to the power grid and the motor gets its magnetic field supplied by the grid in the form of volt-amps reactive VAR.

    First the power grid has three types of power... "real" or the watts you can get out of it... "apparent" the total power or current flowing in the system... "reactive" the power that is not useable in the system... or flows back from the load to the power source or is out of phase and for half the cycle the power is positive (flows to the load) and for half negative (flows back to the generator). Think of a right triangle where the long leg is the apparent power the and the other two legs connected at the right angle are the real and reactive. The real is the only one you can use. But the engine or prime mover has to create enough energy to produce the total of the apparent power... so this is something lost or missing when it come to getting work out of the system... and that is flowing around the system.

    VAR or the missing part of the power the engine puts to the generator but you cannot get out as useable real power is a strange concept as it is not power that is useably produced by the power grid to power a load... it is related to power factor... it that power that is not obtainable from the system. It is just circulating the system around as current that is not useable to produce work out of the system. Note the wires of an AC system must be sized for the apparent power! But there is no free lunch here... you take or draw VAR load off the grid and the generator suppling it simply has to produce more power to feed the grid to keep it in balance. In resistive circuits current and voltage are considered together meaning they are in phase... in inductive circuits the current lags voltage... in capacitive circuits the current lead the voltage... in mixed circuits is in the proportion of the load characteristics. So you can vary the circuits ratio of real to VAR power by changing either load characteristics of the circuit using this concept as VAR is simply power out of phase with the real power. Note in a polyphase system each leg has part of this unto its own.

    As I said the induction type generator (induction motor run as a generator) uses some of the reactive energy of the grid to power its magnetic field to generate electricity. You can compensate for this by adding capacitors to the system... or correct it and change the ratio of the legs of the power triangle. Now you want the maximum work out you need the real power leg longer than the reactive or var leg... so us sparky guys play around with modifying the systems characteristics... there are limits. If you have too little reactive power flowing in the system otherwise you can create over currents in the system which will put you down and dark.

    So how does all this apply to a diesel electric system.

    To describe the hypothetical system simply you could have:
    1. A diesel connected to a induction generator (squirrel cage induction motor with capacitive balance added) connected to a the main power distribution grid of the boat with a frequency motor controller between the motor and the grid... but the frequency motor controller would have a feedback loop in its control circuit that was feed by a tachometer or speed sensor on the engine. And, this loop would be tied into a propulsion control system computer.

    2. A conventional generator connected to the power grid of the boat... as you would usually use for hotel or non propulsion loads.

    3. A propulsion motor (an induction squirrel cage motor) connected to the propeller and electrically to the grid through frequency motor controller which is controlled by the propulsion control system computer.

    How it works:
    The helmsman calls up a specific speed for the boat in his speed control on the bridge through the propulsion control system. Whereupon the computer calculates the speed needed from the propulsion motor. Then sets the frequency controller on the propulsion motor to the corrects speed. This creates a power demand on the main power grid of the boat. The computer senses this power demand and commands the correct propulsion engine speed matched to the stored output characteristics of the engine and the induction generator... meaning a frequency on the speed controller they are connected to the grid with. The engine generator turns at its best speed for economy and the situation and the controller matches the frequency of that "motor" to the main distribution grid of the boat.

    You ask why not use PM generator and propulsion motor... its voltage control. The system explained works on one voltage which is that of the grid. This make the electrical distribution equipment similar for the induction generator / motor system. If you use very simple PM machines then you have to have built in voltage control which isolates the machines from the grid with another level of electrical complication... as they produce wild voltage dependent of generator speed and load... and the motor will draw whatever amps it needs to meet the commanded speed... so you can really get bad things going on with current flow within the system and it makes the wires bigger and the system more complex in the equipment needed to have the PM simplicity.
  14. karo1776

    karo1776 Senior Member

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    Brain,
    Sorry for the spelling and grammar errors... engineers often are totally clueless in such matters... and or creative in such uninteresting matters.

    Another possible choice is a DC based system utilizing PM toothless motor and generator combination. Remember all rotating electrical machines like motors and generators are basic AC machines. The DC is made or used by commutating the output or input to the line or grid.

    This requires a separate propulsion grid unless the hotel loads are powered by inverters off a DC grid to supply regulated AC power to the various auxiliaries, as most are made only in AC standard versions.

    What is a toothless machine?
    Well remember I said that the electrical efficiency is tied to flux density; the conduction/magnetic effects of the coil conductors, an ;it is also tied to losses due to magnetizing iron cores of the windings and also changing the direction of the magnetic fields in those windings as the machine rotates.

    The magnetic reversals require time too. The base windings of the power or magnet coils are made around iron pole pieces to concentrate and intensify the magnetic field... in both stator or rotor. But in a PM machine the rotor is usually a permanent magnet... so it does not have windings. Anyway, the iron pole pieces have coils of wire wrapped around them in the stator of the machine. The iron takes up space but also intensifies the magnetic force created by the coils... taking up space decreases flux density... intensifying the magnetic force increases flux density. So six of one halve a dozen of the other. In normal speed devices 1800 3600 rpm the changes of magnetic direction in the poles can be made more efficient by the making the iron pole pieces in laminations which reduces losses. Go real fast and the losses due to the pole reversals get proportionally larger. Also, it turns out the more turns and more conductors used for the coils for a given current loading the higher the magnetic force. And, the Iron retains heat in the machine limiting its current loading or density... and conversely the flux density. It turns out if you eliminate the pole piece... or iron teeth you can get higher efficiencies, flux density and power output.

    Joe Denk of Allied Signal invented this about 30 years ago. How it was done was to get rid of the iron go to very fine wire called Litz.

    Litz wire is a type of cable used in electronics to carry alternating current. The wire is designed to reduce the skin effect and proximity effect losses in conductors in windings or coils. if I explain this you will be totally bored.

    Anyway if you use a very strong PM as the rotor and get rid of the iron pole pieces or teeth; pack in the windings very densely around it; use litz wire windings, and; run cooling oil pumped through the windings you can make a more efficient and powerful motor or generator in a smaller space... ultimate in flux density. Unfortunately, the electronic commutation takes more space than the basic electric machine! And, unfortunately the machine likes high speed and diesels are pretty low speed. But for large power outputs the sweet spot reduces the speed requirements. So for a 100 kw machine it may fit in your hand but need 100,000 rpm but for a 1000 kw machine the speed might be reduced to 5000 rpm and the motor or generator be the size of a 2 kw conventional machine. But increasing size decreases the rpm needed... so a 1000 kw or 2000 kw motor generator can be designed to work with conventional diesels. Significantly reducing the mass and size of the diesel electric system.

    That is the key to practicality on most yachts of diesel electric and hybrid systems make them similar in mass and power density to convention diesel direct propulsion. That is the driving factor behind this suggestion.
  15. Innomare

    Innomare Senior Member

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    I just read the article of Nigel Calder - indeed finally someone who backs up with numbers what I have been saying for years. The conversion losses in diesel-electric installations don't match up to their fuel savings for motoryachts.

    Just the conclusion is a bit strange to me. He has effectively demonstrated that the hybrid propulsion package for motoryachts is actually a "comfort" issue and that in most usage scenario's the fuel consumption will be (much!) higher than with a (well-designed) direct-diesel configuration, yet he calls for legislation to promote the use of hybrid technology. Why? So our harbours would be quieter and more pollution-free. But this is at the cost of the rest of the environment.
  16. Marmot

    Marmot Senior Member

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    Ahh, finally a realistic and rational response. Thank you Innomare!

    My personal take on this entire discussion is that it is based on the dream of doing something different for the sake of doing something different. The proponents generally have no direct experience with marine electric propulsion and little understanding of when and where that mode is most appropriate.

    An enhanced technical vocabulary does not make up for breadth and depth of application specific knowledge. If there is any such thing as a Marine Engineering Mutual Masturbation Society (hereafter known as MEMMS so as not to offend the overly sensitive), it is almost certainly headed by the proponents of small scale marine electric propulsion and hybrid drives.
  17. karo1776

    karo1776 Senior Member

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    Hybrids
    True the losses particularly in long range transport add up in all hybrids to cost more in fuel consumption than direct drives... always been that way.

    The benefit in cars and surface transport is in stop and go situation where you can recoup losses in regenerative braking.

    In Marine applications for around the harbor low speed operation it is mainly that you can use small ships service generator at its fuel efficient point rather than a large propulsion diesel outside its fuel efficient point... that gives the small advantage.

    Diesel Electric... non hybrid
    That is the subject of the thread... the reason many of us are interested in yachts is the ability to control the "quiet reliability" for more pleasure enjoyment. And, improve maneuverability and some other operational benefits.
    The problem is as you point out the fuel consumption and as I point out the equipment (conventional) available really are impractical for yachts under a minimum of 60m.

    I think when I start doing some musings and discuss in a very very simplified manner the engineering it gets scary for non engineers. If I really explained it a book would result... and would be stuffed full of hard to understand concepts that are tied to higher level math. So when I mention in past posts multimillion dollar development costs you can now understand why those seemingly crazy numbers... they are very conservative.
  18. karo1776

    karo1776 Senior Member

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    Almost forgot my other interest in diesel electric is the corrosion benefits...

    What I save in corrosion protection will pay for any extra fuel wasted and hopefully more...

    I am planning on converting an old tramp steamer to a diesel electric yacht...

    To use it is a test bed for some ideas and don't want to go to to much bother... with hauling it out stripping the hull as that can be a bottomless pit sometimes...

    I figure if I hook up things right... and ground everything to the hull...

    I can save on zincs and by berthing between a couple aluminum hulled boats and leaching off them for corrosion protection

    With what I save for the pocket book on zincs might even be able to have a designer to put in a fancy interior... thinking maybe Remi Tessier... to make it acceptable on the Riviera.
  19. karo1776

    karo1776 Senior Member

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    Seriously, I have come to the conclusion the best place for diesel electric on a reasonably sized yacht 30-50m is as a small electric motor mounted between the main engine and the propeller shaft. Wherein the main engine can be disengaged from the drive and electric motor....

    Or as a retractable auxiliary electrically driven pod drive.

    The power comes from one or more of the ships service generators... might need some upsize for this or running a couple together.

    The propose is slow speed operation and maneuverability. Not ocean transits where standard direct drive from the engines through transmission to the shaft is more effective.

    But it is nice to scheme for some of us.
  20. Innomare

    Innomare Senior Member

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    Karo, did I just read that correctly that you are going to save on your zincs to pay for a Remi Tessier interior?