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Thread: Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine

  1. #1

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine

    .... and some things to do with it

    I) Opening Accolade

    Of Tesla's celebrated forgotten inventions the Mechanical Oscillator proudly stands second to none in obscurity. While many claim to have heard of and to have opinions about its much praised or maligned but generally completely misunderstood sophisticated younger brother, that Monarch of Machines, the Tesla Turbine, few will claim any knowledge at all about what is arguably the best piston fluid heat engine design ever.



    Here are a few quotes from Tesla himself about the engine and how it came to be:

    The Problem Of Increasing Human Energy, With Special References To The Harnessing Of The Sun's Energy
    The Century Illustrated Magazine, June 1900.

    ".. I finally conceived a combination of apparatus which should make possible the obtaining of power from the medium by a process of continuous cooling of atmospheric air. This apparatus, by continually transforming heat into mechanical work, tended to become colder and colder, and if it only were practicable to reach a very low temperature in this manner, then a sink for the heat could be produced, and energy could be derived from the medium.".

    ".. the primary object of which was to secure the greatest economy of transformation of heat into mechanical energy. A characteristic feature of the engine was that the work-performing piston was not connected with anything else, but was perfectly free to vibrate at an enormous rate."

    ".. the engine which I have named "the mechanical oscillator." In this machine I succeeded in doing away with all packings, valves, and lubrication, and in producing so rapid a vibration of the piston that shafts of tough steel, fastened to the same and vibrated longitudinally, were torn asunder. By combining this engine with a dynamo of special design I produced a highly efficient electrical generator, invaluable in measurements and determinations of physical quantities on account of the unvarying rate of oscillation obtainable by its means. I exhibited several types of this machine, named "mechanical and electrical oscillator," before the Electrical Congress at the World's Fair in Chicago during the summer of 1893, in a lecture which, on account of other pressing work, I was unable to prepare for publication. On that occasion I exposed the principles of the mechanical oscillator, but the original purpose of this machine is explained here for the first time."

    "In the process, as I had primarily conceived it, for the utilization of the energy of the ambient medium, there were five essential elements in combination, and each of these had to be newly designed and perfected, as no such machines existed. The mechanic oscillator was the first element of this combination, and having perfected this, I turned to the next, which was an air-compressor of a design in certain respects resembling that of the mechanical oscillator. Similar difficulties in the construction were again encountered, but the work was pushed vigorously, and at the close of 1894 I had completed these two elements of the combination, and thus produced an apparatus for compressing air, virtually to any desired pressure, incomparably simpler, smaller, and more efficient than the ordinary."


    To more fully understand the significance of the features incorporated into the Mechanical Oscillator's design let's briefly discuss some of them:

    First is the operating principle that the Prime Mover, 'the work-performing piston' Tesla mentioned above, be isolated from the load. This basic step which is ignored in offerings presented to the public today, except for a few gas-electric hybrid automobile power systems, ensures longer mechanical life and lower maintenance costs by the simple expedient of eliminating excessive stresses brought on by varying load demands.

    It also allows for engines designed to run within a constant speed range commiserate with their most efficient operation thus lowering manufacturing as well as operating costs. Hydraulic systems pretty much accomplish the same thing through the use of an accumulator to respond directly to load demands while the primary pump supplies the accumulator. Most of Tesla's electrical systems did the same thing via banks of condensers which energized the secondary load circuits while the main generators supplied the condenser arrays. This same concept can be found in aircraft such as the legendary military cargo plane, the C-130 which uses constant speed engines in conjunction with variable prop blades to control thrust.

    Also while this fact seems to be almost completely overlooked or ignored, the innovative use of an Air Spring to stop and reverse reciprocating motion eliminates the crank assembly and with it the costs and complexity of its shafts, bearings, lubrication system, etc., not to mention the attendant weight, friction, wear, maintenance, and breakage associated with it all. Since this 'bottom end' found in most steam and IC piston engines accounts for up to 60 - 80 percent of manufacturing and operational cost, weight, and maintenance, if this isn't a big deal, what is?

    For those who will cry out: 'But what about getting that reciprocating motion turned into rotary motion?!' This is where the principle of separating the prime mover from the load comes into play. Tesla's gen-sets powered by Mechanical Oscillators use reciprocating magnets, not rotary; the exact same principle used by those emergency shake and shine flash lights so popular a few years ago. Tesla was the first proponent that I know of for hybrid power systems, in his case he advocated reciprocating steam Oscillator engines to run electrical generators to power rotary electrical motors for both boats and trains. In a similar fashion a Mechanical Oscillator driving a pump module can power a hydraulic system which feeds rotary hydraulic motors. Many industries with heavy duty in-house transport needs regularly use hydraulic powered vehicles because of their rugged and low maintenance attributes. These power systems are not used in public offerings partially because of the huge negative economic impact it would have on the parts and service industries.

    For sheer elegance of design the Mechanical Oscillator is just about unmatched. Not only does its design eliminate the bottom end crank assembly, it also eliminates independent valves and timing mechanisms. If you have ever looked at the diagrams for large steam engines, especially large stationary ones for manufacturing plants, or seen them operating you can get an idea of the sheer mechanical complexity involved in just getting those valves timed correctly. The Mechanical Oscillator doesn't have independent valves or timing systems, it has a single moving shaft-piston component - lets say that again: 'it has a single moving shaft-piston component' - of which the power piston through the use of plenum grooves and internal channels together with precisely placed intake and exhaust cylinder ports, acts as its own valve assembly and timing mechanism.

    And if that isn't enough, remember those bearings that got thrown out with the crank assembly? Well, all of those from the main crank bearings to the piston wrist bearings were load bearings subject to constant stress and requiring a dedicated lubrication system. The few bearings the Mechanical Oscillator does have are all sliding bearings which are a completely different animal altogether.

    To finish up this opening accolade of the Mechanical Oscillator it is not out of place to point out that, just as in the case of hybrid power systems, Tesla anticipated the ***anese revolution in high speed automotive engines. And once again he out did his future competitors, as while the rpms of today’s engines range from 5,000 to 10,000, the Mechanical Oscillator worked at frequencies of 60,000 or so with a stroke of around three eighths of an inch or 9.5 mm for the intelligentsia amongst us.

    All praise to the Magnificent Mechanical Oscillator.




    References:

    The Problem Of Increasing Human Energy, With Special References To The Harnessing Of The Sun's Energy
    http://www.tfcbooks.com/tesla/1900-06-00.htm

    Tesla's Oscillator and Other Inventions
    by Thomas Commerford Martin
    http://www.tfcbooks.com/tesla/1895-04-00.htm

    1894-01-02, US Patent 511,916 Electrical Generator
    1894-02-06, US Patent 514,169 Reciprocating Engine
    1894-04-10, US Patent 517,900 Steam Engine


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    @ C. Kurtz 2014 This content is offered under CreativeCommons by sa-3.0

  2. #2

    II) Components and Operation

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it


    II) Components and Operation


    The Mechanical Oscillator fluid heat engine is a constant period resonance device designed to operate at high oscillation frequencies, with the low mass and extremely short stroke associated with such devices.

    Basic components consist of: 1) a power Piston (Tesla's work-performing piston), 2) a common Shaft extending completely through the housing, and 3) an Air Spring; which combined together form the only moving unit in the whole design.




    The power Piston itself can be viewed as being composed of five equal width longitudinal sections (5N), with two circumferential grooves separating the end sections from the central section.

    Matching this construction, the cylinder bore has precisely centered longitudinally around it a circumferential band composed of five sections each also 1N in width. The two end sections, each containing a cylinder Exhaust Port, and the center section, containing the cylinder Inlet Port, are separated from one another by two solid bands. Each Port opening is precisely centered on its section, but is made slightly narrower (e.g. if N = 10 mm then each port could be 8 mm in width).

    This design allows the power Piston to function as a sliding valve controlling the in-flow and out-flow of the motive medium: steam or gas under pressure. In this valving capacity when at Null Center the power Piston's two end sections block the two cylinder Exhaust Ports, while the Piston's center section blocks the cylinder Inlet Port. Movement in either direction unblocks the ports and directs the in-flow of the motive fluid alternatively from one Piston face to the other.

    This valving function necessitates a piston throw of 1N in either direction requiring a minimum cylinder internal length of at least 7N. (The accompanying images show an additional .5N on each end for cushioning which may or may not be needed.)

    The Air Spring acts as a unbreakable shock absorber slowing the advance of the power Piston, stopping it before it crashes into the cylinder head, and then releasing the energy absorbed to send the piston back along its reciprocal path. If you've ever watched deer, antelope, or other physically fit animals, or some people for that matter, you will recognize the complementary interplay between two halves of a whole recognizable by a natural fluidity and 'bounce' to their movements.

    The Air Spring itself is somewhat optional in that the oscillation control function can also be incorporated into the design of application modules which can be placed on the common shaft, such as electrical generators, compressors, or others which exhibit compression load type characteristics.

    In addition if intake fluid is directed around the Air Spring housing the radiated heat of compression can act in a pre-heating role.




    The Mechanical Oscillator’s elegant minimalist design was also envisioned as an adaptable platform to allow for stacking additional power modules and the use of various application modules, such as hydraulic pumps, etc. It can operate in either the horizontal or vertical positions.

    During operation, the two power Piston Grooves act as plenums enhancing communication with the cylinder Ports and the power Piston's internal fluid Channel rim ports, which are located in the grooves. The grooves alternate between the cylinder's inlet port and the exhaust port opposite the piston face their channel communicates with. Together the grooves and fluid channels serve as both inlet and exhaust ducts. The accompanying images show the top Piston channel communicating with the left end of the cylinder exhausting through the right cylinder Exhaust Port, while the lower Piston channel communicates with the right side of the cylinder and exhausts through the left cylinder Exhaust Port.




    A single pair of channels is shown for simplicity's sake; however, two pair would provide superior ventilation and load distribution. The exact dimensions of the Air Spring would be a matter of empirical testing and adjustment to the selected motive fluid pressure and load range. This should be made easier by the fact that the Air Spring's design, as a 'leaky' pneumatic device, allows for wide latitude in adjustments.

    In summary, from all indications the Mechanical Oscillator is a very durable, low maintenance, high efficiency, easy to manufacture, low cost design which eliminates a multitude of parts, e.g. valves, cranks, fly wheels, load bearings, etc., and the accompanying parasitic losses normally associated with piston engines in general.




    @ C. Kurtz 2014 This content is offered under CreativeCommons by sa-3.0
    Last edited by ckurtz; 03-16-2014 at 03:32 PM.

  3. #3

    III) Fun Stuff: The Square Wooden Atmospheric - Vacuum Engine

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it


    III) Fun Stuff: The Square Wooden Atmospheric - Vacuum Engine



    A while back I had access to a wood shop and a nice 3D program, Rhino 4. Having seen a couple YouTube videos demonstrating square wooden atmospheric engines using cranks and sliding-valves I was motivated to make a similar Oscillator engine to put them to shame. Unfortunately before any practical work could be done time moved on and so did I.




    Still, I find the thought of a square wooden Oscillator somewhat hilarious and in the hopes someone with more talent and the proper tools might think so too and actually build one to post a video to show the world I offer these incomplete plans and observations.

    How It Works - or should: Hook up your shop vac or your wife's dainty house vacuum to the suction port and hit the switch. The connection between the vacuum chamber and the Oscillator section is through a series of holes drilled through the second Partition from the left, which is marked as element (3) in the above component image. These holes connect with the space in between the Exhaust Chamber box (6) and the power Piston Cylinder box (4) which shows three slots per side. The slot in the middle is a continuation of the central Inlet Port slot seen in (6) and (5), while the two end slots are the Exhaust Ports. With the vacuum established ambient air will enter through the Inlet Ports exerting pressure on one side of the power Piston (11) depending on the piston's exact position. In the case of it being at Null Center a sharp rap on the end of the shaft (Tesla's actual recommendation) extending through the right end partition will motivate it to move off center and start working. As long as a vacuum is pulled and nothing breaks or seizes up it should run - hopefully in a blur of reciprocating motion.

    Plans: Having never done so before, I thought working in actual A4 print size might be useful so I made the plan images ungodly large; something I will not do again. Use only for reference not for actual building. *(I'll post the links as soon as I re-size them and get them uploaded - no matter what people may tell you vector graphics don't necessarily scale all that well...)

    Although I cleaned the plans up for posting here, it has to be stressed that this was only a preliminary design at best. For one thing I have no idea what the real tolerances would be for making a wooden Oscillator; will wood give you one millimeter tolerances? If not how large do they have to be; this is important especially for sizing the ports which directly influences the piston length as it is composed of five equal sections which interact directly with the cylinder ports for the valving function. So, although I left the measurements intact on the plan images they were only meant to be used as references or place holders subject to change, and it's probably best to just ignore them.

    A couple more observations about the design in general are probably in order. I decided to add a separate vacuum section for connecting to a vacuum hose instead of just devising slot connections directly to the power Piston Cylinder because I wanted an axial connection without radial hoses. This was partly for aesthetic reasons - I mean who wants something that looks like an aborted Borg? But if you don't mind it can probably be simplified - it just won't be as pretty and Maclom Reynolds will probably be somewhat disappointed - but that's okay, he's disappointed a lot as we all know...

    Another item I'd like to touch on is the size of the Air Spring piston in this design. It is small relative to the power Pistons Tesla shows in his patents and what I use in other designs. The difference here is that this is an Atmospheric engine, it only works on ambient air pressure not on hi-pressure steam or compressed air of several bars. Because of this I thought that a smaller piston sized to achieve higher compression ratios would work just as well as a larger lower pressure one. That might or might not be correct; since I never built it I never found out if it would or if it would just burst all asunder..!

    Anyway, if someone gets inspired enough to build something I'd sure like to hear about it, especially if it puts those silly wooden sliding-valve crank designs to shame...




    Wooden Air Engine 2009: http://www.youtube.com/watch?v=ngb4SYR74m4

    Wooden Air Engine 2011: http://www.youtube.com/watch?v=A5LVhivWiVo


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    @ C. Kurtz 2014 This content is offered under CreativeCommons by sa-3.0

  4. #4

    IV) The Tesla - Giffard Combine

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it


    IV) The Tesla - Giffard Combine



    The Venturi Jet Injector

    In 1738 famed scientist Daniel Bernoulli (1700-1782) published his work 'Hydrodynamica' in which he formulated the principle that as the speed of a fluid increases, the lateral pressure it exerts decreases. How this works can be approximated next time you find yourself in a long unobstructed hallway. While facing down the hall get close enough to a wall so you can reach out to the side and push on it, the amount of lateral force you can exert will drop dramatically as you start walking faster and then break into a run.

    In 1797 Giovanni Battista Venturi (1746-1822) observed the corollary effect that fluids flowing in a pipe would speed up when forced through a constriction into a smaller pipe and the ensuing lowering of the stream's lateral pressure would enable it to entrain surrounding fluids.

    Lowered pressure is another way of saying lowered opposition, and when dealing with fluids this devolves to opposition to the movement of the particles making up a fluid mass. While not speaking directly on fluid mechanics, one of the best descriptions of the underlying process was given by Tesla's favorite mentor, William Crookes, in his 1879 address 'On Radiant Matter':

    "Gases are now considered to be composed of an almost infinite number of small particles or molecules, which are constantly moving in every direction with velocities of all conceivable magnitudes. As these molecules are exceedingly numerous, it follows that no molecule can move far in any direction without coming in contact with some other molecule. But if we exhaust the air or gas contained in a closed vessel, the number of molecules becomes diminished, and the distance through which any one of them can move without coming in contact with another is increased, the length of the mean free path being inversely proportional to the number of molecules present. The further this process is carried the longer becomes the average distance a molecule can travel before entering into collision..."

    It is through this mechanism that lowered pressure zone gradients expand into a fluid medium surrounding a high speed jet which entrains the constituent particles of the mass as they eventually find themselves following the paths of least resistance. *(just a note to point out before someone says otherwise, that entrainment is _not_ the nefarious practice of making an innocent appear to be complicit in conspiring and carrying out dastardly schemes... Entrainment _is_ the brilliant force multiplier capability inherent in fluid dynamics for co-opting the energy and vitality of formerly aimless bystanders into a focused cohesive group effort which is a distinguishing characteristic of Order over chaos...)

    A milestone regarding Venturi Effects was reached in the 1860s when French academic, Prof. Henri Jacques Giffard, developed and patented a venturi based steam-jet water injector which used a small amount of steam from a boiler, such as those found on the old beloved by all steam locomotives, to inject _all_ of the make-up water the system requires right back into the very boiler the injection steam came from. Impossible, right? That is what most academics, engineers, and other self-appointed establishment spokesmen said when the idea was first put forward. However, Giffard produced a working device and steam venturi jet injectors and their multitudinous off spring soon became ubiquitous industry standards, found nearly everywhere fluid systems are used.




    They work because Giffard could visualize the interplay between the characteristics of the motive fluid, steam, and that of its lower temperature denser state, water, in differing conditions. Basically if hot expanded steam interacts with water at the right temperatures the steam will condense forming a low pressure zone more steam will accelerate into and while moving through a venturi will pick up and mix with the very water that will condense it, accelerating the water to nearly the velocity of the steam stream in the doing. As this now mostly condensed highly accelerated composite stream passes through a divergent tube its speed decreases while its pressure increases until when it reaches the one-way valve back into the boiler, its much greater density and momentum overpowers the opposing steam - magic of sorts in the form of fluid dynamics.

    All right, one may ask, what the devil has this got to do with Tesla and his Mechanical Oscillator? Ah! Ye of little faith and smaller memories, have you so quickly forgotten Tesla's comments quoted in the Opening Allocade?

    ".. I finally conceived a combination of apparatus which should make possible the obtaining of power from the medium by a process of continuous cooling of atmospheric air. This apparatus, by continually transforming heat into mechanical work, tended to become colder and colder, and if it only were practicable to reach a very low temperature in this manner, then a sink for the heat could be produced, and energy could be derived from the medium."

    In the mid-1800s Giffard had conceived of using great fiery steam boilers to power vacuum creating jets, and in the late 1800s Tesla stood the concept on its head by creating a null center of low pressure cold by using the power of solar heated ambient air to run his Mechanical Oscillator as an atmospheric engine driving a compressor. In addition, he could also capture the heat of compression from his compressors to pre-heat expanding liquid air, then capture more heat from the surrounding environment to drive another Oscillator by expansion. Both approaches incorporated phase change relationships and demonstrated their creators' brilliance.

    Some who look askance at the thought of exploding steam boilers or dealing with limbs frozen solid by immersion in liquid air, may wonder if there is a non-extremist approach that might achieve similar results. As it so happens steam isn't the only motive fluid used in venturi jet injectors as nearly any low viscosity fluid can be used - water and air work fine at ambient temperature as long as they are pressurized enough to effect a high speed flow through the device. In fact non-steam injectors are much less complicated in design as the need to address steam's phase change inside the injector is eliminated. *(It's probably best to point out that technically, according to Strickland, _only_ condensible motive devices should be called Injectors; however, I hope no one minds if I use the term in its generic sense as it describes the process so well.)

    The design of jet injectors is, as their name implies, closely related to that of De Laval nozzles, also commonly known as rocket nozzles, which minimize the chaotic motions of particles making up a fluid mass while maximizing their orientation and speed along a common pathway. There are two basic jet injector designs related to whether or not the motive and suction fluids are similar or dissimilar, and whether or not mixing of the two is important. Designs for similar fluids, especially two liquids with no mixing demands can be of simple converging nozzles with minimal throat lengths and diverging sections; while dissimilar fluids with high mixing requirements require converging nozzles, relative long mixing throats, followed by similarly long diverging nozzles.



    Strickland pointed out in 1898 that Giffard's first design addressed all the basic scientific concepts needed for successful implementation of the Injector, and that all subsequent improvements were due to attention to details and improved manufacturing techniques. By then commercially available injectors were able to reach steam jet velocities of over 3,400 feet per second, achieve entrainment ratios of 1 lb of motive steam to 13 lbs of water, and inject this mass economically back into boilers operating at up to 150 psi. Modern versions of jet injectors, eductors, gas burn off Tulips, etc. commonly claim 1:20 volume entrainment ratios, with some specific application designs claiming ratios of over 1:50. Again these results are mainly due to improvements in manufacturing and materials which allow greater fit between physical dimensions and actual flow shapes.

    (continued)

  5. #5

    IV) The Tesla - Giffard Combine (cont.)

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it

    IV) The Tesla - Giffard Combine (cont.)


    Heat of Compression: To pursue our quest for a little bit of natural philosophical jujitsu to attain our goal of a working Tesla-Giffard hybrid, now is a good time to look more closely at the Heat of Compression mentioned previously in regards to Tesla's air compressor design. This phenomena relates to the fact that as a gas is compressed the energy required to maintain the now reduced mean distance between its mass of unceasingly agitated constituent molecules is decreased and this now excess energy either radiates away or goes into raising its temperature and pressure. For instance the surface area of a 1 cubic meter sphere is around 4.836 square meters, while that for 0.5 cubic meters is about 3.046 square meters. The larger sphere has about 158% more surface area, while inversely the smaller has only about 63% of the larger. It is pretty easy to see that if all the molecules that fill a larger space are crammed into a smaller one, or vice versa, the number of impacts per unit of surface area is going to drastically change, as is the mean distance a molecule can travel before a collision occurs.

    To see how this works lets compress 2 cubic meters of ambient air (14.7psia, 288 degrees Kelvin, density of 1.2kg/cubic meter) into a 0.5 cubic meter volume. First let's do it the easy way following Boyle's Law which lets the heat-of-compression go off on its own so pressure is a simple inverse function of volume.

    Boyle's Law: P2=P1V1/V2 = (14.7psia*2cubic meters)/1cubic meter = 29.4psia

    Now let's try it when there is _no_ heat loss. *(note: I'm not a mathematician so beware..) The sign 'y' = gamma = cp/cv = 1.4; gas constant 'R' = cp - cv = 0.287; rho = density.

    P2 = P1(V1/V2)^Y = 14.7psia(2/1)^1.4 = 14.7psia*2.639 = 38.79 psia
    T2 = T1(rho2/rho2)^Y-1 = 288K(2.4/1.2)^0.4 = 288K*1.3195 = 380 degrees K

    Perfect utilization of the heat-of-compression has the potential to increase both pressure and temperature about 31 per cent. Of course in the practical world perfection is unobtainable; however, it can be worth striving for.

    Internal Compression: Normal mechanical compressors are separated from the pressure tank and treat the heat-of-compression, along with the increased pressure potential, as a waste product which is radiated away from the housing and pipes. Internal compression as the name implies, moves the act of compression inside the pressure vessel.

    While there are various ways this can be accomplished, for our purpose here we will focus on combining Tesla's Mechanical Oscillator with the venturi jet injector. Here the oscillator, the compressor/pump, and the injector(s) are all placed inside the pressure tank. Once the tank is pre-pressurized, the surrounding fluid drives the Oscillator as an internal hydraulic PTO (power take off) device with the fluid exhausting to a non-pressurized reservoir. The compressor / pump's supply is also the surrounding fluid which it pressurizes to supply the motive jet for the Injector which creates a low pressure area ambient air, and or make-up water can move into. Once there the intake fluid becomes entrained with the high speed water jet, mixed thoroughly in the throat passage if needed, and is then injected from the diverging section as a high pressure stream directly into the pressure tank itself where any remaining pressurization is quickly accomplished by the resident compressed air.

    As an example of this I give you the Mark-10 tgc Heat-of-Compression Hand Pump:




    To see how all this (supposedly) works let's first set some conditions:

    A: Compress 4.2kg of air @ 14.7psia @ 288K @ density = 1.2kg/cubic meter, into a one (1) cubic meter volume which is considered constant. The water volume is also considered constant as it is replaced nearly as fast as it is used. Assume _no_ heat losses.

    B: To begin the pressure tank is at the above ambient conditions. The first stage in this example is the pre-pressurization by hand, followed by the action of the Oscillator-Pump-Injector.

    C: The Mechanical Oscillator and Pump are affixed to a common shaft so the stroke of each is the same. The working surface area of the Oscillator's power piston is double that of the Pump's piston, so the Pump's output is always double the tank pressure driving the Oscillator - normal losses for such systems are ignored here.

    D: The Injector's ratio of motive fluid to entrained suction intake fluid = 1:5.

    In this configuration, for every cubic meter of water exhausted through the Oscillator, the Pump will deliver 0.5 cubic meters of 2X pressurized water to the Injectors which will draw in (0.5 * 5) 2.5 cubic meters of intake fluid. With water replaced at a 1:1 volumetric ratio 1 cubic meter of the intake is dedicated to make-up water, leaving 1.5 cubic meters for fresh intake air, or an additional 1.8 kg of air added to the 2.4 kg already present for a total mass of 4.2 kg.

    Including the pre-pressurization stage, this results in an 'Ideal' pressure increase to 84.92 psia, and a temperature increase to 475.59 K (202.59 C | 396.66 F).

    Where the sign 'y' = gamma = cp/cv = 1.4; gas constant 'R' = cp - cv = 0.287; rho = density. Solve for P2, T2, and E1.

    P2=P1(V1/V2)^y = 14.7(3.5m3/1m3)^1.4 = 14.7(5.78) = 84.92psia
    T2=T1(P2/P1)^(y-1)/y = 288K(84.92/14.7)^0.286 = 288K(1.651) = 475.59K
    E1=cv*m*T2 = 0.718*4.2*475.59K = 1,434 kJ

    ...

    Disclaimer of sorts: Please note there has been no practical prototype development of this specific design approach to date, so although most of the concepts are based on existing devices or valid principles, all of which are in the public domain, it is still more or less in the thought experiment stage. The primary unanswered question here is whether or not Tesla's Mechanical Oscillator can perform adequately as a hydraulic instead of a pneumatic device, which is what it was designed as and which all the literature I know of refers to it as. Originally I thought this design would function with a normal pneumatic oscillator; however, using compressible air as the motive fluid introduces some severe limitations that the use of basically incompressible water does not. There are probably hydraulic devices that can serve the same mechanical purpose at lower efficiencies, but of course not the same sentimental role.

    In any case if you want to be the first to amaze your off-road groupies by pumping up a flat Monster Truck tire by hand, or amaze them even more by blowing it off its rim, then start building your own Magnificent Tesla-Giffard Combine Heat of Compression Mark-10 today! And if you think you'll be amazed just think how amazed I'll be....




    References:

    On Radiant Matter
    British Association for the Advancement of Science Lecture
    by: William Crookes, 22 August 1879

    Practice and Theory of the Injector
    by: Strickland L. Kneass, 1898
    http://www.archive.org/


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    @ C. Kurtz 2014 This content is offered under CreativeCommons by sa-3.0
    Last edited by ckurtz; 03-16-2014 at 03:47 PM.

  6. #6

    V) Solar Augmented Heat-of-Compression Fluid Power Systems

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it


    V) Solar Augmented Heat-of-Compression Fluid Power Systems



    Background: This design approach was developed over the past year or so due to an interest in providing a practical alternative to the traditional high temperature solar heat engine designs with their dependence on reflective surfaces, tracking mechanisms, special thermal transport fluids, and other temperamental fallible costly high maintenance schemes and their generally abysmal overall thermal efficiencies which are not well suited for small scale non-commercial power applications.

    The primary philosophical principle here is that our atmosphere provides the most practical dependable solar heat reservoir available to earth bound inhabitants, and since for all practical purposes air is still free and can't be permanently broken, frozen, or evaporated it might be a sensible idea to make use of what Mother Nature in her bounty has so generously given us.

    Variations Three on a Theme: With that in mind what follows is pretty much just variations on the concepts discussed in the previous chapter, with the addition of passive solar heating units, and the expansion from the small mobile utility device design of the Mark-10 to that of stationary thermal solar power installations serving farms or small communities.


    Example 1: Simple Air Compressor using air as the motive and suction fluids - or - How things get difficult real fast. This example is mainly to clarify why hydraulic motive injectors are better suited for this type of application than pneumatic. Compressed air serves the external load.

    A: Pre-pressurize by compressing 2.4kg of air (@ 14.7psia @ 288K @ density = 1.2kg/cubic meter), into a one (1) cubic meter volume which is considered constant. Then exhaust one (1) cubic meter of pressurized air through the Mechanical Oscillator. Assume _no_ heat losses. Solve for Pf, Tf, and Ef.

    B: To begin the pressure tank is at the above ambient conditions. The intake air during the Oscillator's operation will be heated to 338 degrees K by the solar panels.

    C: The Mechanical Oscillator and Pump are affixed to a common shaft so the stroke of each is the same. The working surface area of the Oscillator's power piston is double that of the Pump's piston, so the Pump's output is always double the tank pressure driving the Oscillator - normal losses for such systems are ignored here.

    D: The Injector's ratio of motive fluid to entrained suction intake fluid = 1:5.




    From the above conditions it can seen that for every cubic meter of compressed tank air that powers the Oscillator and exhausts to the atmosphere, half a cubic meter of compressed tank air will be drawn into the compressor and delivered to the Injector as a quarter cubic meter of air at twice the pressure. At the ratio of 1:5 the Injector will then draw in (.25 * 5) 1.25 cubic meters of ambient air.

    While from a volumetric view point things don't look all that bad, from a mass perspective this is a disaster, for the cubic meter of pressurized air exhausted driving the Oscillator had a mass of 2.4 kg, while the 1.25 cubic meters of intake ambient air only had a mass of 1.5 kg. In this scenario the pressure will fall from 38.79 psia to 18.97psia.

    Where the sign 'y' = gamma = cp/cv = 1.4; gas constant 'R' = cp - cv = 0.287; rho = density. Since the original 2.4kg air mass was entirely replaced by the 1.5kg intake mass we can solve this just using the intake values. Solve for Pf, Tf, and Ef:

    Pf = P1(V1/V2)^y = 14.7psia(1.25/1)^1.4 = 14.7(1.291) = 18.97psia
    Tf = T1(P2/P1)^(y-1)/y = 288K(18.97/14.7)^0.286 = 288K(1.29)^0.286 = 309.77K
    Ef = cv*m*Tf = 0.718*1.5*309.77K = 333.62kJ
    *(I got a Tf of 314.87K when using the formula Tf = T1(rho2/rho1)^y-1; don't know why but it certainly indicates I did something wrong...)

    This design fails because of the variable relationship between volume and mass the compressibility of air engenders. As the following examples demonstrate this problem is eliminated with the substitution of basically non-compressible water as the motive fluid.


    Example 2: Air Compressor using water as the motive fluid, with air as the primary suction fluid & water as the secondary, or, the Mark-10's big brother. Compressed air serves the external load.

    A: Pre-pressurize by compressing 2.4kg of air (@ 14.7psia @ 288K @ density = 1.2kg/cubic meter), into a one (1) cubic meter volume which is considered constant. The water volume is also considered constant as it is replaced nearly as fast as it is used. Then exhaust one (1) cubic meter of pressurized water through the Mechanical Oscillator. Assume _no_ heat losses.

    B: To begin the pressure tank is at the above ambient conditions. The intake air during the Oscillator's operation will be heated to 338 degrees K by the solar panels.

    C: The Mechanical Oscillator and Pump are affixed to a common shaft so the stroke of each is the same. The working surface area of the Oscillator's power piston is double that of the Pump's piston, so the Pump's output is always double the tank pressure driving the Oscillator - normal losses for such systems are ignored here.

    D: The Injector's ratio of motive fluid to entrained suction intake fluid = 1:5.




    In this example the former compressor is now a pump delivering 0.5 cubic meters of pressurized tank water to the Injectors instead of the 0.25 cubic meters of air of Example 1. The Injector's performance ratio stays at 1:5, so for every cubic meter exhausted by the Oscillator the Injector will draw in (0.5 * 5) 2.5 cubic meters of intake fluid. With water replaced at a 1:1 volumetric ratio, 1 cubic meter of the intake is dedicated to make-up water leaving 1.5 cubic meters for fresh intake air, or an additional 1.8 kg of air added to the 2.4 kg already present for a total air mass of 4.2 kg in the cubic meter volume.

    Including the pre-pressurization stage, this results in an 'Ideal' pressure increase to 89.32 psia, and a temperature increase to 511 K (238 C | 460.4 F).
    Where the sign 'y' = gamma = cp/cv = 1.4; gas constant 'R' = cp - cv = 0.287; rho = density. Solve for Pf and Tf.

    Step One: Compress 2.4kg of air @ 14.7psia @ 288K @ density = 1.2kg/cubic meter into 0.5714285 cubic meter. Assume _no_ heat losses. Solve for P2, T2, and E1:

    P2=P1(V1/V2)^y = 14.7(2m3/0.57m3)^1.4 = 14.7(5.78) = 84.92psia
    T2=T1(P2/P1)^(y-1)/y = 288K(84.92/14.7)^0.286 = 288K(1.651) = 475.59K
    E1=cv*m*T2 = 0.718*2.4*475.59K = 819.54 kJ

    Step Two: Compress 1.8kg of air @338K into a 0.4285714 cubic meter volume. Solve for P2, T2, and E2:

    P2=P1(V1/V2)^y = 14.7(1.5/0.4285714)^1.4 = 14.7(5.78) = 84.92psia
    T2=T1(P2/P1)^y-1)/y = 338K(84.92/14.7)^0.286 = 338K(1.651) = 558K
    E2=cv*m*T2 = 0.718*1.8kg*558K = 721.16kJ

    Step Three: Combine the above results in a 1 cubic meter volume with rho3 = 4.2kg. Solve for Pf & Tf:

    Tf=(E1+E2)/(cv*rho3)=(819.54kJ+721.16kJ)/0.718*4.2=(1,0540.70)/3.0156 = 511K
    Pf=(rho3*R*Tf)= 4.2*287*511 = 615,852.33Pa / 6895Pa/psi = 89.32psia

    (If all air is solar boosted final temp = 558K @ 97.55 psi)

    (continued)

  7. #7

    V) Solar Augmented Heat-of-Compression Fluid Power Systems (cont.)

    Tesla's Magnificent Mechanical Oscillator Fluid Heat Engine
    .... and some things to do with it


    V) Solar Augmented Heat-of-Compression Fluid Power Systems (continued)



    Example 3: Hydraulic Power Unit using water as the motive fluid, with water as the primary suction fluid and air as the secondary. A Hydraulic PTO serves the external load. Change in the internal volume and mass of water is the primary compression method. The internal volume of water is variable; the internal volume of air is variable, the internal mass of air is semi-variable as it could serve a 'top-off' HOC function.




    I haven't bothered with a mathematical analysis for this example partly because my eyes are crossing, but mostly because the basic concepts should be clear enough by now for anyone who has gotten this far to understand well enough what is going on to figure things out for themselves.

    This example takes the hydraulic approach initiated in the 2nd example a step further changing the device from an air compressor to a full-fledged hydraulic device. Compression pressure now is mostly a function of variations in the volume of water; the air mass remains mainly constant but its volume varies inversely to that of the water.

    While the design seems much more complex the use of water as the sole motive and load driving fluid should simplify the operation and reduce maintenance to a great degree. Two separate Injectors are shown because the heat of compression plays more of a secondary role in this design in regards to regulating pressure and the demand for air is not as closely tied to that of water as in Example 2.

    The relationship between exhaust and intake fluid remains basically the same as discussed above in Example 2; the main difference is that a greater percentage of the intake is dedicated to make-up water to either replace PTO usage or increase the mass / volume of the internal water to increase the pressure. Air intake is primarily dedicated to maintaining the air mass and fine tuning the pressure range via the heat of compression possibly in conjunction with a finely calibrated blow-off valve. In fact it might be that a hybrid design incorporating pneumatic load serving capabilities could prove practical.

    Closing Thoughts: When I first started thinking along the lines that have eventually led here, I thought the system would be entirely pneumatic in operation and entirely uninsulated. However, as it turns out hydraulic injectors are required and insulation is needed not only to prevent freezing in cold climes, but to retain as much internal heat as practical.

    Even though the use of water injectors requires consideration of cold weather factors this is not necessarily something to be too concerned about, as the designs can adjust by either putting temperature controlled shut-off valves on outside solar water panels, eliminating them altogether, or building them into the heated structures housing the primary pressure vessels. At first I thought heated structures were a very negative issue, however, in truth in cold climates, such as Alaska, all rural residences and commercial facilities have insulated and warmed pump houses anyway. The more I have considered it, especially the idea of the passive solar panels being built into the structure the more appealing it has become. In any case the use of low temperature passive solar thermal panels provides for a much more robust, efficient, and accessible system than any high temperature tracking design can ever achieve - which was the goal after all.

    For those wondering whether or not venturi injectors are suitable for compression applications, according to Strickland Kneass' 1898 'Practice and Theory of the Injector', commercial versions of Giffard's steam jet venturi injector which were capable of achieving somewhat phenomenal motive flow speeds - over 3,400 feet per second, were commonly able to inject 8 to 13 pounds of water using 1 pound of steam back into boilers operating up to 150 psi. Today's commercial steam and non-steam injectors come in all types, forms, and names depending on their specific function. Pneumatic motive fluid models, such as air handlers and gas field burn-off Tulip devices can commonly move air at volumetric ratios of 1 unit of motive gas to 20 of entrained air or higher. Cheap hydraulic units hooked up to your faucet can move air at volumetric ratios greater than 4 units of air to 1 unit of water; while units specifically engineered and manufactured for a particular application can achieve much greater ratios.

    There are other more elegant ways to achieve internal compression. This small introduction to the subject is offered in the hopes that it will encourage and possibly inspire others to investigate further the magical potential of fluid dynamics.




    @ C. Kurtz 2014 This content is offered under CreativeCommons by sa-3.0

  8. #8
    Networking Architect Aaron Murakami's Avatar
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    You should talk to Peter Lindemann, he shares your passion about Tesla's "self acting heat engine."
    Aaron Murakami





    You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete.” ― Richard Buckminster Fuller

  9. #9
    Wow, you really did a lot of work! I really need to get in touch with my high school math teacher. I remember 20 years ago (give or take a few), saying dumb things like "when am I ever gonna use this in the real world?". Well, apparently every day. I was just explaining to my kids who were learning how to find volumes of containers that I was just doing the same thing, designing a pump, finding the area of the piston times stroke times rpm for flow. Anyway, I've spent the last 3 years in my shed working out the details of an ambient air engine that was so simple on paper! A scroll compressor (running as expander), a 30 plate heat exchanger, yards of misc copper tubing, fittings, valves, etc. Even home built thermoelectric generator/ heaters/ coolers, pulse tube cryocoolers (performance to be determined) and a tesla turbine/ pump thingy (large diameter turbine with small dia pump on same shaft). I guess you could say I'm working on a cold (cryogenic?) Rankine cycle. The basic idea being pump a cold liquid (ln2 if ambitious, propane if u don't want to spend 3 years in the shed) through heat exchangers cooling the returning nitrogen, picking up additional ambient heat, spinning turbine, returning to liquid container via heat exchanger. At least that would be the "on paper" version. The real thing involves Joule Thomson valves, many heat exchangers, 2 cycle motors converted to air motors, etc. Because the tesla turbine pump can't get the liquid to high enough pressure, I wanted to design a air powered hydraulic plunger pump to use the piston ratios to step up the pressure. That's when Irremembered the oscillator, thought I'd Google it to see how those "valves" worked, and found your post. My design is also inspired by Tesla's PWIHE (long title!). I noticed he came up with his theory for the ambient engine after seeing air liquefaction (was it Claude, Linde, Kelvin?). He also used the water flowing in a cup analogy that really made sense. If you pump out water (heat), more water (heat) can flow in, which at best leaves us breaking even. However, if some of the water (heat) is converted to hydrogen and oxygen (work), then you don't have to pump as much out as comes in (a gain!). Since the best way to get compressed gas to lose heat is to make it do work, this is pretty convenient! Of course its never quite that easy, but using latent heat properly and using good materials (stress, thermal conductivity, etc) it can be done. The cold fluid absorbs ambient heat, expands to high pressure, does work, losing heat, then gives remaining heat to the warming liquid being pumped via heat exchanger, then JT valve for final liquefaction. This a slight simplification, there are other details such as how to recirculate unliquefied gas , volume and pressure flows, etc. Search ORC cycles, and its already being done with propane using waste or solar heat, but the holy grail is ambient! I like your thinking and will probably use the oscillator/ hydraulic pump design you show, although putting it inside the tank would evaporate the LN2 supply. I just like knowing I'm not the only insane person trying to save the world (its a tough job but someone's gotta do it). Its also interesting to see other ideas. You came up with a totally different idea from the same inspiration. Actually reminds of a compressed air forum I've seen. The injectors are a totally different approach from anything I've seen. After making the nozzle for the tesla turbine I think I'd purchase an injector instead of my usual "maybe I can make one!) attitude. If I had $, I'd buy a cryogenic liquid pump but I'm guessing a HP one would cost more than my car. I'd love to work with you and test some ideas. I've been reading old books online about steam engine valves, etc. Why are there such things as valves? Tesla made them obsolete 100 years ago! The system in the oscillator is nothing short of genius, and his valvular conduit solves other valve issues. Just wish it was easy to make like most of his other inventions! Thanks for sharing! Andy

  10. #10
    Andy:

    Sorry about the delay in responding. I forgot this forum doesn't have email notification for new postings just for private messages, and I don't stop by very often as you can tell. I sent you a PM with a contact email address as I do appreciate your comments and hearing about your research activities.

    This particular design is what someone over on another forum refers to as a working A1 model that demonstrates the conceptual potential albeit in a more limited form from that of a more optimal design. The whole motivation behind it came from briefly being somewhat enthused at what the folk over at Open Source Ecology dot Org were promoting, especially since their engine of choice was supposed to be the Tesla turbine. My interest began to wane when the disorganization of the site began to be somewhat suspect, i.e. perhaps partially deliberate in order to cover up certain things such as the trashing of the turbine in favor of a 9% efficient bump valve steam engine - it takes a real collective of geniuses to make a decision like that... However, because at one time I had been pretty deeply involved in solar concentrator/collector design I had gotten somewhat interested in perhaps helping them out in that regards as they were knee deep in re-hashing every mistaken approach taken by almost everyone over the years: i.e. go for high temperature high concentration tracking collectors which are about the most inefficient concept ever because of the inherent high losses associated with high temperature systems; and because tracking systems almost never compensate for their high initial costs, or the fact that they are generally responsible for 80% or so of ongoing maintenance costs - meaning they break down a lot. From previous work I was pretty sure I could put together a low temperature compressed air system using just ambient air run through cheap stationary solar panels which would provide more power more reliably for less cost than any high temp system they could put together. However, by that time I was getting less and less impressed with their organization which seemed to have pretty much fallen under the establishment's sway as exemplified by their often quoted operational mantra that they would focus only upon 'proven' technology: i.e. f__k Tesla and his turbine and stick with gasoline engines... So instead of providing them with an optimal design I thought I would just turn out a somewhat limited capability version and see what they would do with it.

    However, de-tuning a design and still having something that works good enough is about on par with stiffing the F-22 for the F-35 - the result ain't pretty and it sucks. I banged my head against the wall for almost a year before it finally got through my thick skull that the modified approach I was working on had to use a hydraulic motive fluid, and once I figured that out then it finally came together fairly well, even if it isn't overly elegant. Anyway by then I had decided I didn't want anything more to do with the open source folk, and just posted the plans here as I appreciated what Aaron was doing for Dollard. I didn't expect much of a reaction as this forum's members are pretty much into secret magical electrical stuff, and I wasn't disappointed which is okay.

    It sounds as if you are more or less following the direction described by Tesla in creating a null center of sorts through liquefying a gas and using the resulting pressure differentials to tap energy from the surrounding ambient medium that moves inward towards the lower pressure center, and then also taps the energy from the revitalized liquid as the heat drawn from the incoming medium vaporizes and re-expands it.

    Am not sure if you noticed or not but the design I posted does not tap the inward motion directly, only the outward movement of the pressurized hydraulic fluid powering the mechanical oscillator driving the high pressure pump which supplies the motive stream for the injector. The high velocity of the motive stream creates the low pressure zone inside the injector which the ambient fluid and replacement fluid move into. Trying to extract energy from this movement would restrict the amount entering the injector which would prove fatal to its operation. The energy is extracted but that occurs only after entering the injector where the compression by the surrounding high pressure air begins and finally completes as the mixed stream moves out into the high pressure tank itself. This is where this design differs from most compressors because there is no mechanical compressor per se, since the motive fluid is a liquid it is moved by a pump not a compressor, and it is the resident compressed fluid that does the actual compression of the indrawn ambient fluid.

    This design only works if the hydraulic fluid stays a liquid both while serving as the injector's high velocity motive stream and while in the external non-pressurized reservoir. Using a gas or vapor as the motive fluid involves compression losses that off-set the greater than one ratio of suction fluid to motive fluid the injector provides. I am mentioning this just to point out that this design will not work with a single fluid, such as LN, trying to provide both the gaseous element and the hydraulic element because somewhere along the line the liquefied element is going to vaporize and when that happens then this design fails. In fact while I forgot to mention it in the posting it is possible that heated pressurized water might still retain enough energy after powering through the mechanical oscillator to turn to steam in the reservoir; I doubt that would actually prove to be the case but if so then probably some sort of oil would have to be substituted.

    As far as modifying your design to use the mechanical oscillator instead of the turbine, I don't see why not as that was what the oscillator was specifically designed for. However, the turbine is probably capable of achieving the necessary compression levels if staged properly which it does much more elegantly than piston compressors.

    Again my apologies for missing your post, drop me an email if you do eventually see this.

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