More About the Stirling Steele.pdf

7/28/2019 More About the Stirling Steele.pdf

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More About the Stirling Steele:

In the Stirling-Steele engine, four gamma type Stirlings are daisychained together. This is done by driving the displacers via linear driverods which are attached to the top of power pistons. The rods pass thrua sealed bulkhead and the displacer cylinders are ported to power

piston cylinders that are phased behind them 90 degrees. This allows anengine that only requires one crank throw per piston where othertypes of Stirlings require two. Fewer crankcase penetrations along witha simpler crank permit for a more cost effective engine to manufacture.

Building four cylinder engines instead of single cylinder units hasseveral strong advantages such as easy starting, good balance, smoothrunning even at very low speeds, increased heater and cooler surfacearea and good low end torque.

As an external combustion engine, the Stirling-Steele engine caneasily meet the EPA standards for carbon monoxide and hydrocarbonemissions. Since it is a closed cycle device, it runs very quietly without

the need of a muffler.Volume = 2.25 cu-in rpm=1000Pressure = 40 psi Helium or T hot=~600 degrees C

= 20 psi air Tcold=70 degrees CHot heat exchanger = unfinned shellCold heat exchgr = 24 channels 0.0625 x 0.0625 x 0.625 in.Regenerator = stainless steel cloth 0.625 x 8.75 in., 60 meshDrive = Sinusoidal beveled gearsPower output = 40 Watts max (Helium)http://www.stirlingsteele.com
http://www.stirlingsteele.com/http://www.stirlingsteele.com/http://www.stirlingsteele.com/


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The following numbers are based on what I have seen in the above video orstatements the speaker has made and in a few cases, guesses based onwhat I can see. All my dimensional estimates are strictly eyeball and mayeasily be off by 20% or even more.

Sunpulse Stirling engine generating electric power

power piston diameter: est. 48 inchespower piston stroke: est. 2.5 inchesdisplacer diameter: est. 48 inchesdisplacer stroke: variable, est. 2.5 to 6 inchesflywheel diameter: est. 72 inchesflywheel rim: est. 0.5 inches thick by 4 inches wideOperating RPM: est. 60 to 90Heating and cooling pumps: est. 2 inch diameter by 3 inch stroke, double-acting

29.4 cubic inches per stroke = 312 grams (for water)Operating temperatures: Hot oil or water at 5 bar pressure, 150 to 200 deg C.Water cooling, est 25 degC or higher

Estimate operating gas temperature Th=180 deg C, Tc=40 degCPower output of generator: 1.5 kWEngine pressure variation: +/- 0.1 bar (approximate in video of gauge)Hot oil with possibly gravel stored in elevated barrel est. 55 gal barrel

Stirling engine driving water pump

flywheel diameter: est. 48 inchesflywheel rim: est. 2.0 inch diameter steeldisplacer stroke: est. 5 inchesclaimed pumping output:400,000 liters/day, zero head(110,000 gal/day or 9200 gph for 12 hr day)80,000 liters/day, 10m head(22,000 gal/day or 1800 gph for 12 hour day)15,000 liters/day, 50m head(4100 gal/day or 340 gph for 12 hour day)

total solar collection diameter est. 11 feet including mirrors

There are several interesting features of this engine that Ive tried to capturein these stills taken from the video. First, the robust power piston with what Iwould describe as a conical truss. If you want to get significant power out of alow-temperature Stirling engine, you need a big power piston. I estimate thepower piston at 48 inches in diameter. combine that with a pressurefluctuation of about 0.1 bar (1.5 psi) shown on the gauge in the video and youhave a peak piston force of around 2700 lbs.


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An atmospheric Stirling engine such as this will have an approximatelysinusoidal pressure versus time with two power peaks per revolution. One halfthe cycle will be above atmospheric pressure and one half will be belowatmospheric pressure . The average force =.64 x peak force or about 1730lbs. I estimate the power piston stroke at 2.5 inches so for a complete cyclethe travel is 5 inches for a total of 8650 in-lbs of work or 721 ft-lbs per cycle.At 60 RPM this would be about 980 watts. This gets you in the ballpark of1500 watts. At rated power this engine might be turning 90 rpm, the pressuremight be even higher, or my power piston diameter and stroke estimatescould be way off.

To me the most interesting feature of this engine was the variable-strokedisplacer. The following photo labels some of the components. A motor-drivenjack screw (which you can see operating in the video) adjusts a connectingrod anchor point on the lower displacer lever. When the connecting rod isclose to the pivot the piston travel is long and when it is farther away the travelis shorter.
http://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-power-piston1A.jpg


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The reason you want to do this is to be able to quickly regulate the poweroutput of the engine to match the load. The time constant for heating orcooling the engine might be minutes, but you need to adapt to electrical loadchanges much faster. This mechanism lets you operate the engine at a fixedtemperature and be able to vary the displacer stroke to control the RPM.Closed-loop RPM control using this method is much better and less wastefulthan say adding or dropping a dummy load to flat-load the engine.

The above photo also shows what I refer to as a rolling fabric seal around thecircumference of the power piston that provides an airtight seal to the cylinder.The seal is probably a coated fabric that is flexible but does not stretch underthe 1.5 psi operating pressure.

This last photo shows the engine-driven piston pumps that pump both the hotoil or water through the hot end of the engine and the cooling pump. Both ofthese pumps appear to be double-acting so they pump liquid twice percomplete cycle.
http://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-lower-displacer-lever-1B.jpg


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This is quite an impressive project. Also see some information at Sunvention.

Posted in Uncategorized | No Comments

Solar-powered Stirling engine design details

December 24, 2011 2:48 pm

Ive put together a video of the latest version of the LT-2 Stirling engine.Because this low-temperature engine has minimal output power I sometimesconsider it more of an artwork than an engine. I often refer to it as thesculpture engine.

Quasiturbine Stirling Engine (Sterling)Short-Steam-Circuit Engine

Rotary Hot Air MotorHeat pump

QT Short Steam Circu it Stirling simultaneously improvesboth high and low pressure, and speed pressure transition without heat

regeneration device:Flash steam is a very fast process that produces a much higher pressure that

heating a gas.

Furthermore, steam condensation is also a fast process producing a muchdeeper vacuum that the cooling of a gas.
http://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.sunvention.com/sv/produkte3.htmlhttp://www.sunvention.com/sv/produkte3.htmlhttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/category/uncategorized/http://www.solarheatengines.com/category/uncategorized/http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/http://www.solarheatengines.com/2011/12/24/solar-powered-stirling-engine-design-details/http://www.solarheatengines.com/2011/12/24/solar-powered-stirling-engine-design-details/http://www.solarheatengines.com/2011/12/24/solar-powered-stirling-engine-design-details/http://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpghttp://www.solarheatengines.com/2011/12/24/solar-powered-stirling-engine-design-details/http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/http://www.solarheatengines.com/category/uncategorized/http://www.sunvention.com/sv/produkte3.htmlhttp://www.solarheatengines.com/wp-content/uploads/2012/01/sunpulse-heating-cooling-pumps1A.jpg


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Up to 16 times more power than a Stirling piston enginewith comparable chamber volume!

Case study for a 50 kW (67 hp) unit(Helium or water-steam mode Quasiturbine Stirling engine)

A new, powerful, liquid or pressurized-gas Stirling Engine, Heat pump &Cryocooler

for use in submarine or free-space thermal gradients,and in vehicles with radio-isotope or solar cogeneration.

* * * * *A Stirling will always be Stirling

The objective is not to compete with other types of machines, but with otherStirling engines.

Stirling has its own environmental benefits in particular applications.

* * * * *

Consider a Quasiturbine without any intake or exhaust port,where all the chambers are filled with the same quantity of a compressed gas,and suppose that two opposed quadrants are heated to a high temperature,

while the two others are cooled.

Initiating the rotation will move the cool gas (or liquid water) into the hot areaswhere it will expand (evaporate) and produce a torque which moves it

into the followings quadrants where it is cooled (condensed) again, and soon.

This rotation is provided by two opposed closed gas circuits working

simultaneouslyon the Stirling thermal engine principle

(mechanical work produced by a closed fluid circuit simply from a constantheat flow between two hot and two cold poles,

as opposed to hot air engines which are hot-monopole devices,since they generally intake fresh air at ambient temperature and exhaust their

hot residual gas).Since there is a lag time in the gas temperature variation,

it is desirable to apply the heat with some advance on their respectivequadrants.

Since the gas is moved sequentially, rather that alternately, from the zones of

different temperature,the Quasiturbine Stirling has no need of a regenerator and loses


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no efficiency,which increases its RPM and power output.

The Quasiturbine also has no need for a "gas displacer".The Quasiturbine Stirling is not self-starting, and has a preferential direction of

rotation.

Leaks of hydrogen or helium (which have good conductivityand the highest gas pressure response per temperature increment change)

are known as a weakness of the Stirling engine.In the Quasiturbine Stirling, the engine shell is filled with pressurized helium,

and inter-chamber leaks are automatically recycled by the central region,requiring only the sealing of the turning shaft

(compare this to the difficulties of sealing pistons).The Stirling engine is also known to be large and heavy,

which the Quasiturbine Stirling concept should solve.

Quasiturbine Heat PumpDriving this device with an external motor

will also move heat from one quadrant to the next.The hot compressed gas will give its heat to a quadrant

while the following gas expansion will take heat (cold) from the next one.In reverse cycle, this device is a complete loop

and an integrated "Quasiturbine Heat Pump" with heat exchangers.(Such a compact device is not possible with a piston pump

because both compression and expansion occur at the same physicallocation,

which it is not the case with the Quasiturbine)Furthermore, no polluting gas or liquid is required.

The air-cooled or liquid-cooled component can be hot or cold, as needed.

4 pole Quasiturbine Stirling concept


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loading requires less mechanical energy in the absence of preheating andprecooling, which makes the regenerator less effective than one may think).Power increases as gas temperature differences increase in the chamberbetween the cold gas TDC intake and the hot gas BDC end; whichmeans, from a mechanical point of view, that the gas should get the coolest

possible entering the hot chamber, and the hottest possible entering the coldchamber (as in the Quasiturbine). Sure, the regenerator lowers thermalenergy consumption, but it also lowers mechanical output, with limited effecton total efficiency. It should be noted that the problem is not with theregenerator concept or with having it in the system, but with the time frame inwhich it works, and also with the extra chamber volume it often adds to thepressure system. The regenerator adds to time constants in the process andlowers the maximum engine speed. The lack of a regenerator in theQuasiturbine is not for space/weight/power density considerations, butbecause there is never any back flow since the gas is progressing forward allthe time, so there is no real need to incorporate temporary heat storage in a

regenerator. This is a case where expertise in the world of engines andthermodynamics has failed, until now, to discover the ingenuity and the simpleprinciples of the Quasiturbine.

Thermal transitional effect ( "hot and cold" losses): The fluid (gas orvapor) faces the "cold" side when it first begins to be heated by the hot side,and similarly, the fluid faces the "hot" side when it first begins to be cooled. Itis important to notice that heat exchange is done radially, and not byconvection from the beginning to the end of the chamber. Consequently,when the fluid leave a chamber side for the next, it is already at the "behind"side chamber temperature, and little happened to this fluid until it gets facingthe next chamber side temperature plate. For this reason, the temporarycoexistence of the fluid in the two chambers during transitions is not a thermalwaste at all.

Torque continuity, RPM and Power:The Stirling cycle produces pressure variations seen by the pistonalternatively as pressure and vacuum. In good working condition, the Stirlingpiston is pushed during gas heating and pulled during gas cooling, but thosetwo forces never act on the piston at the same time. The resultinginstantaneous torque on the piston is more constant (but less powerful) than

in the internal combustion engine because it has 2 positive contributions oftorque of about 90 to 120 degrees duration each per revolution - that is, onepush and one pull. For each revolution of the Quasiturbine rotor, each one ofthe four pivoting blades receives a push at the top and bottom hot plates(approximate angular location), and a pull at the left and the right cold plates,that is 2 pushes and 2 pulls on each of the four piston blades per revolution,

or a total of 16 torque impulses per rotation which level out the instantaneoustorque fluctuations, increase the power density, and remove the need for aflywheel (substantially reducing the engine weight and size even further).Because each Quasiturbine pivoting blade goes through 2 pushes perrevolution compared to 1 for the Stirling piston, the same time constant would

means that the Quasiturbine rotor RPM would be half the Stirling piston RPM.However, time constants in the Quasiturbine are anticipated to be quite short,


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so that about the same RPM can fairly be expected. Consequently, based onequal chamber volume, a Quasiturbine Stirling rotor will produce up to 16times more power than a piston Stirling (8 times due to the geometricalfrequency, and 2 times due to the RPM), hopefully with less than 16 times theheat flow, and this does not take into account other valuable improvements

like the elimination of inter-chamber tubing connections which will greatlyincrease the maximum pressure and vacuum.

The inter-chamber tubing connections:The conventional Stirling engine needs inter-chamber connecting pipes tocarry the gas to and from the cold and hot areas (displacer-side spacing playsthe same role). Those pipes are passive extensions of the compressionchambers, and since they are kept at a near-constant intermediarytemperature, their gas content attenuates rather than actively contributes tothe pushing effort. The Quasiturbine Stirling concept has no need for suchinterconnecting pipes, and allows for higher peak pressure in the chambers,

and consequently higher specific power density.

The Quasiturbine Stirling operation:This concept moves the gas around in a way that eliminates the need for theregenerator, which is quite imperfect in other Stirling engines anyway. It is thepurpose of the Stirling to work by bringing the most possible heat by gasabsorption from the hot area to the cold area. The Quasiturbine concept doesit both frequently and without a regenerator - both sources of its higher powerdensity. More heat moved by gas absorption equals higher engine poweroutput. Furthermore, one should remember that when parallel surfaces movepast one other, gas trapped between them will tend to roll in the direction ofthe moving surface, due to its adherence to the two surfaces, which ensuresthat when the gas comes up in the new zone in the following chamber it isessentially attached to the pivoting blade surface. This roll effect is soimportant in the Wankel engine that a second sparkplug is needed in the backchamber area to prevent combustion squelching. This roll is less important inthe QT, but it contributes to convective heat transfer within the chambers.

Quasiturbine Steam-Circuit Stirlingengine: (Quasiturbine Short-Steam-Circuit engine - Phases change mode?) To increase the heat flow transferrate, this Quasiturbine Stirling engine can be operated with a fluid such

as water where steam is produced in the hot zones and condensed in the coldzones. This requires only a small quantity of liquid water, which the centrifugalforce of the Quasiturbine rotation can maintain permanently in contact with theperimeter for an optimum heat transfer. Ultimately, this option could also beconsidered as an attractive Quasiturbine Stirling Steam engine.

Calculation method for Quasiturbine Power sizing

Some preliminary hypotheses:

1) To reduce thermal loss and allow optimum efficiency, let's suppose that the

hot and cold stator zones are made of an excellent thermal conductor, that theintermediary insulation has low thermal conductivity, and that the lateral


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engine sides and the pivoting blades are made of ceramic of very low thermalconductivity (or of conducting material coated with insulation).

2) Let's assume that the average gas temperature fluctuation in each chamberis from 100 degrees C to 400 degrees C during the rotation (a temperature

differential of 300 degrees C). This may require that the cold zones are keptunder 50 degrees C (a 50 degree C rise to account for gas temperaturediscontinuity at the surface and the gradient within the cold plate), and the hotzones are kept over 600 degrees C (a 200 degree C drop to account for gastemperature discontinuity at the surface and the gradient within the hot plate).This may also consequently require that the burner temperature be of theorder of 1000 degrees C (an advantageous high temperature permitting toburn dust and solid particles responsible of Smog).

3) Let's assume that these temperature fluctuations (and correspondingpressures) are produced at the optimum angle in stationary regime operation,

which means approximately when the ends of the pivoting blades are at thelimits of the hot and cold zones. This may require that the thermal quadrantseparation insulators be placed at a shifted angle (positive or negative, to becalculated by engine computer simulation) in reference to the rotation, so asto compensate for the thermalisation time lag due to the delay of heattransfer. The thickness of these inter-chamber insulators may also beadjusted to minimize the transitional thermal effect between the differenttemperature zones, mainly during pressure increase where the gas mayslightly flow back into the insulation area. Before initiating a thermal transitionzone, one can reasonably suppose that the gas is thermalized with its facingstator surface, and when the forward section of the pivoting blade passes theinsulator toward the next thermal zone, the thermal variations occur only inthis forward section, the section behind the separator insulation being alwaysthermalized to its previous environment.

4) Lets assume that the gas thermalisation time constant permits eachchamber to go through 24 thermalisations cycles per second. Since eachchamber accomplishes 2 cycles per revolution, this give 12 revolutions persecond, or 720 RPM.

5) Let's assume that the Quasiturbine can initially be uniformly pressurized at

the absolute pressure of P0 (bar or Atmospheres at ambient temperature, andgenerally with helium) in the chambers (square configuration in order to havethe same quantity of gas in each of them, or making use of check valves inthe pivoting blades toward the central region) and also in its empty centre(constant volume). The only leaking area would then be the seal of the exitingrotating shaft of the Quasiturbine, which a standard seal will easily make leakproof. On the other hand, this sealed enclosure could contain oil forlubrication, if required.

6) Ignoring the pressure fluctuations due to the geometric compression ratio(simulating a ratio of 1:1, equivalent to 2 interconnected out-of-phase pistons

with the total volumes being constant), the temperature fluctuationsmentioned in 2) will produce by themselves average pressure fluctuations


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from Pmin = 1.33 P0 (bar or Atm.) to Pmax = 2.33 P0 (bar or Atm.), a simpleratio of absolute temperature, meaning a pressure differential betweenchambers equal to P0. As for all Stirling engines, notice that the higher P0 is,the more important the pressure fluctuations will be and the higher totalengine power produced will be (a good way to rapidly control the output

power, rather than by acting on the hot temperature zone, assuming anaccess to the chambers by the central region of the Quasiturbine via checkvalves in the pivoting blades).

7) Stirling engines generally operate with low compression ratios, even if theyrespond simultaneously to a thermal compression ratio and a geometriccompression ratio (both are time variable, and the product of both ratios givesthe real ratio). In fact, it is probable that little gain can be made by selecting ageometric compression ratio which would raise the gas temperature byadiabatic compression behind the temperature of the hot zones (except foraccelerated heating by gas density and proximity effect, which would make it

possible to achieve higher RPM). For the present calculations, we suggestputting aside the effect on efficiency due to the geometric compression tocompensate for various losses still little studied. Note, however, that theQuasiturbine Stirling permits much higher compression ratios than the pistonengine, and consequently less gas mass, which improves efficiency.

8) Heat flow bottle neck: Heat flow is like water in a pipe network: themaximum flow is controlled by the bottle neck element, and a good efficientdesign is made of a sequence of elements having equal flow capability at fullpower, no more, no less. In thermal gas-solid devices, this is furthercomplicated by the gas contraction-expansion effect (ignoring radiation) bywhich a gas flow is more efficient to heat a cold object (on which the hot gasis attracted by contraction) than to cool a hot object (on which the cold gasexpands away). Reciprocally, an object is more efficient to cool a gas (whichhot gas is attracted by contraction) than to heat it (which cold gas expandsaway). Consequently, heat exchange flux between a solid and a gas shows adiode effect, which induces an hysteresis effect in the reversibility. The properargument applies here on the outside of the Quasiturbine-Stirling, but morecritically inside, where the transition from a cold chamber to a hot chamber willincrease the pressure and produce a small reverse flow into the cold behindchamber, which will demand a relatively longer angular hot pole. Conversely,

a transition from a hot chamber to a cold one will reduce the pressure andproduce a small forward flow which will accelerate the cooling, requiring ashorter angular cold pole for the same heat flow. Such optimization will makea better performing design, but will destroy the reversibility, for which anotheroptimized machine should be designed.

Lets apply these hypotheses to the case of the Quasiturbine QT400: TheQuasiturbine QT400 model (400 cc per chamber) has a rotor diameter of 28cm (11 in.) and a thickness of 10 cm (4 in.), each chamber having a maximalvolume of 400cc.. The internal surface of the hot zone (same for the coldzone) is about 20 cm (8") along the perimeter by 10 cm (4") thick, there are 2

hot zones, so that the total internal hot surface is 400 cm2

(64 sq. in.) and thesame for the total cold surface. About the suggested design, the cold area is


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liquid cooled while the hot area is heated through hot gas contact. Notice thatthe external engine hot area extends on the exterior over the cool area toincrease chimney gas contact (which can still be further doubled by the use offins). The diameter of the stator exterior is about 22 cm (8 1/2") and can beextended over the thickness of the engine (say 4 times 10 cm (4") along the

engine axis), and this would give a total chimney surface of about 2500 cm2

(400 sq. in), which can still be further doubled by the use of fins. The thermalflow to produce 50kW mechanical with a 25% efficiency will be 4 X 50kW,which corresponds to an exterior heat flow at atmospheric pressure of 80Watts/cm

2(500 W/sq. in., half of that if fins are used). Internal heat flow at

engine operational pressure will be 500 Watts/cm2 (3000 W/sq. in.), which a 6bar or Atmosphere internal pressure would theoretically balance the externalatmospheric pressure gas conductivity. With an absolute pressure differentialor P0 et 720 RPM, we will have:The torque = 50 x P0 (N-m) or 37 x P0 (pound-feet) With P0(bar or Atm.)

The power at 720 RPM = 5 x P0 (kW) or 6.7 x P0 (CV) With P0 (bar orAtm.)

Taking into account the approximations and the security factors, a first ordercalculation like this one allows us to establish the possibility of producing, inthe said conditions, more than 50 kW mechanical or electrical by pressurizingthe Quasiturbine at only 20 or 30 bar or Atmospheres (generally with helium).Note that few, if any, commercial Stirling engines achieve this level of power!

Need more power? The effect of pressure: The same Quasiturbine Stirlingcould be more pressurized (certain Stirling engines reach 200 bars ou Atmand more), and so produce more power. Because the entire rotor ispressurized, the roughness constraint due to pressurization affects mainly theengine casing (the roughness constraint on the blades depends for its part ofthe relative pressure fluctuation from the chambers). However, it is interestingto note that the thickness of the Quasiturbines (and other rotary engines) ininternal combustion mode is limited by its ability to extract the heat from therotor centre. However, in pneumatic, steam or Stirling mode, the engine isthermalized and it is not required to extract excess heat from the rotor centre,which means that the Quasiturbine Stirling thickness can be considerably

increased, allowing reduction of thermal end effects, and construction of morelinear, more efficient heat exchangers, and allowing production of still morepower from the Quasiturbine Stirling.See investigation of concepts for high power Stirling engines at: http://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.html

2 Poles Quasiturbine Stirling

The concept with 4 poles is complex and can present nodes of null push (?).

One could conceive a hot cycle of compression in one half of theQuasiturbine, and a vacuum in the other cold half? Quasiturbine Stirling with 2
http://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.htmlhttp://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.htmlhttp://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.htmlhttp://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.htmlhttp://www-ifkm.mach.uni-karlsruhe.de/Html-e/Project/Stirling/stirling.html


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poles (a hot half, other half cold) would certainly worth a study to validate thispossibility... (?)

Stirling Concept with 2 Quasiturbines

Dual-Quasiturbines Stirling engine? One hot and one cold? Side by side?On the same shaft? After all, Quasiturbine chambers are analog to pistons,but are making 2 compression-expansion cycles per revolution. Instead ofcooling the hot gas into a cold quadrant, move it from the hot-BDC into thecold-BDC chamber of a cold Quasiturbine located nearby, and when the gashas cooled to cold-TDC, move it back to the hot-TDC Quasiturbine. This willwork, but the back and forth flows could still be one way (without regenerator),which is again not appropriate for "regenerator" fans! However this DualQuasiturbines configuration is not likely to raise the power density or theefficiency(?), because it will introduce holes and maybe pipes as passivevolumes extending from the chambers. As a 2 piston Stirling engine (moving

at 90 degrees out of phase), this method consists of using 2 Quasiturbines,one hot and the other cold, assembled at -45 and +45 degrees opposed toeach other (which makes the chambers 90 degrees out of phase) on thesame common shaft, and permitting the gas to flow back and forth betweenthose two Quasiturbine chambers, either through a regenerator or not. TheStirling mode is then possible because during a rotation from 0 to 90 degrees,the volume of a chamber passes from 0 to Vmax, and that simultaneously therotating shaft from -45 to +45 degrees in the other Quasiturbine, it produces inthe latter a net variation of volume "null". The volume added with the 2coupled chambers being effectively modulated between approximately 1/2chamber and 1 1/2 chamber, varying little during the first 45 degrees, andmuch thereafter (Note that the short circuit concept allows variations ofvolume of 0 chamber with 1 chamber, and offers a stronger compressionratio)...

This concept is simple to understand and to study, but double the equipment.This solution is not as practical for the short-steam-circuit engine. TheQuasiturbine Aviation page http://quasiturbine.promci.qc.ca/QTAviation.htmlproposes a Brayton cycle where two distinct Quasiturbines side by side on thesame shaft share a common pressure area in between, one being the cold-compressor Quasiturbine, the other the hot-power Quasiturbine (notice that

this common in-between pressure has unidirectional flow, unlike the presentStirling Dual-Quasiturbines concept).

Quasiturbine Stirling and Short-Steam-Circuit engine efficiencyconsiderations

Stirling engines use a closed chamber (cylinder and piston) with a fixedamount of compressible fluid (no intake or exhaust). This confined gasis alternatively moved from the hot to the cold end of the cylinder

(generally by using a displacer object free to move within the chamberand taking the place of the gas), producing an alternative expansion-
http://qt.promci.qc.ca/QTAviation.htmlhttp://qt.promci.qc.ca/QTAviation.htmlhttp://qt.promci.qc.ca/QTAviation.html


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contraction pressure variation which does drive a piston on a relativelyshort course. This engine converts a constant heat flow from the hot tocold end of the cylinder into mechanical work with a superior potentialefficiency since it does not exhaust any residual thermal or mechanicalenergy, but it is very limited in total power output density in weight and

volume. However, it can be combined with hydraulic engines to produceimpressive power where power density doesn't matter. Since the gas ismoved sequentially rather that alternately from the zones of differenttemperature, the Quasiturbine Stirling is exempted from the need of aregenerator (not necessarily in the case of two Quasiturbines), whichincreases its efficiency and power output through an increase in RPMbecause preheat and precool increases the chamber charging pressurebefore the TDC, which is mechanically counter-productive. TheQuasiturbine Stirling engine moves the gas around very efficiently, witha higher compression ratio (smaller gas mass), and allows for morepower density. Since there is no exhaust, they are very quiet engines,

and the Quasiturbine Stirling is vibration free.

To have a high specific power density and a high efficiency, it isessential to reduce the time-losses in an engines (to reduce the idleperiods). In all Stirling concepts, there is an obvious considerable lossof time when moving the gas which is often spread out over more than90 degrees of shaft rotation, shortening the push and creating abackpressure. Whereas the researchers unanimously seem to carrytheir attention on the use of regenerators, we believe that theimprovement of Stirling passes rather by an increase in the speed of thegas movement between the cycles of relaxation and contraction, and thesuppression of regenerator (and yes!). Several refuse to understand thatat the time of moving gas, larger are the variations in temperature andmore brutal is the transition of gas between the heat and the cold area,higher the output will be. Output efficiency does not come from theregenerator, but from the speed of this gas movement, which must beimproved in all Stirling concepts (Note that the movement of thedisplacer does not require in theory energy, and how its accelerationdoes not consume anything theoretically!). Although the QuasiturbineStirling shows astonishing characteristics, it is the short steam circuitconcept which offers most brutal transformation and makes it possible

to anticipate a spectacular effectiveness. Indeed, its contour seal isscraping condensation droplets on the cold part (of water or othersliquidate) and brings them brutally on the hot part, creating an extremelyfast transition, highly beneficial to the effectiveness. We believe thesecomments somewhat useful to understand the effect and the limitationsof the Stirling engines, even if it is sometimes inevitably necessary toaccept limitations!

Combined heat cycle with Quasiturbine Stirling engine in GHG Alberta

Solutions Showcase Newsletter
http://qt.promci.qc.ca/GHGAlberta0205.htmlhttp://qt.promci.qc.ca/GHGAlberta0205.htmlhttp://qt.promci.qc.ca/GHGAlberta0205.htmlhttp://qt.promci.qc.ca/GHGAlberta0205.htmlhttp://qt.promci.qc.ca/QTVehiculeF.htmlhttp://qt.promci.qc.ca/QTVehiculeF.htmlhttp://qt.promci.qc.ca/QTVehiculeF.htmlhttp://qt.promci.qc.ca/QTVehiculeF.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://quasiturbine.promci.qc.ca/QTVehiculeE.htmlhttp://quasiturbine.promci.qc.ca/QTVehiculeE.htmlhttp://quasiturbine.promci.qc.ca/QTVehiculeE.htmlhttp://quasiturbine.promci.qc.ca/QTVehiculeE.htmlhttp://qt.promci.qc.ca/QTHydraulique.htmlhttp://qt.promci.qc.ca/QTVehiculeF.htmlhttp://qt.promci.qc.ca/GHGAlberta0205.html


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http://quasiturbine.promci.qc.ca/GHGAlberta0205.html

Stirling Hybrid VehicleApplications are numerous, including in silent,

zero-vibration and low pollution power plant for hybrid vehicle.

http://quasiturbine.promci.qc.ca/QTVehiculeF.html

About the Hybrid Stirling Hydraulic Quasiturbine LocomotiveSee the section Quasiturbine Hydraulic Motor atquasiturbine.promci.qc.ca/QTHydraulique.html

Non-stop nuclear Quasiturbine-Stirling for vehiclewhich could drive a several HP generator continuously for many years

base on a small simple nuclear pellet...http://quasiturbine.promci.qc.ca/QTVehiculeE.html

Notice - These calculations are subject to verification,and the practical feasibility of this principle applied to the Quasiturbine

has not yet been tested experimentally.

To find more about Stirling engine, visit the websites ofStirling Engine Society:

UK - http://www.argonet.co.uk/users/bobsier/inde.htmlUSA - http://www.sesusa.org

Model under development, onlyRESEARCH APPLICATION PROTOTYPES

are available at this time.

Questions

The matter of heat transfer should be well assessed. Considering the detailsgiven previously, the thermal flow to produce 50kW mechanical with a 25%efficiency will be 4 X 50kW. The questions become:

a) From the hot-stator exterior: Is it feasible to flow that much heat powerthought 2500 cm

2(400 sq. in.) gas-metal interface in the chimney (surface

can still be doubled by fins)?

b) From the hot-stator interior: Can this same heat flow be extracted by thepressurized gas from the two hot surfaces totalizing 400 cm

2(64 sq. in.)?

c) From the rotor: Can the internal pressurized gas move this heat flow fromthe hot to cold zone?

d) From the cold-stator exterior: Can the liquid cooled cold-stator zone extract

this kind of heat flow out of the engine?
http://www.argonet.co.uk/users/bobsier/inde.htmlhttp://www.argonet.co.uk/users/bobsier/inde.htmlhttp://www.sesusa.org/http://www.sesusa.org/http://www.sesusa.org/http://qt.promci.qc.ca/QTdesireacheter.htmlhttp://qt.promci.qc.ca/QTdesireacheter.htmlhttp://qt.promci.qc.ca/QTdesireacheter.htmlhttp://www.sesusa.org/http://www.argonet.co.uk/users/bobsier/inde.html


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e) What is the main limiting factor?

f) Are the temperature gradients in the right orders?

g) What is the fair power output of such a design?

h) Is the RPM hypothesis sustainable?

Remember, the objective for now is to bring the hypothesis to fair realisticvalues.

The upper concept works, but the one below will not!Be careful about concept alternatives

This concept is not as simple as many may think. Be very attentive not to betrapped.

For example, avoid the following concept (used by the author as examquestion for his engineering students!):
http://quasiturbine.promci.qc.ca/QTIndex.htmlhttp://www.fas.org/man/dod-101/navy/docs/swos/eng/62n1-16/sld003.htm


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Be careful also when you make comparison between the Quasiturbine StirlingCycle and the "Brayton Cycle" (also known as Joule Cycle) of theturboreactors.

http://www.fas.org/man/dod-101/navy/docs/swos/eng/62n1-16/sld003.htm

Brayton Cycle uses the intermediary transformation of pressure energy intokinetic energy, which allow later the kinetic energy recovery at the samepressure that the chamber intake. Remember that the Quasiturbine ispressure sensitive and requires a higher pressure at intake than atexit,because it does not use kinetic energy transformation. However, twodistinct Quasiturbines on the same shaft sharing a common pressure inbetween may be linked and/or looped (?) (If the first one is a cold highpressure low flow rate, the second one will have to be a hot low pressure highflow rate, providing that some combustion comes in, to increase the flow atconstant pressure like in turboreactor). From a high pressure source like in jetairplane conditioning system, a Quasiturbine compressor could be linked with

a Quasiturbine pneumatic motor through a cooling heat exchanger to act as aheat pump.

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Quasiturbine Vapeur Inc.

Casier 2804, 3535 Ave Papineau, Montral Qubec H2K 4J9 CANADA (514)527-8484 Fax (514) 527-9530

http://quasiturbine.promci.qc.ca [email protected]
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