Quasiturbine Stirling Engine (Sterling) 
Short-Steam-Circuit Engine
Rotary Hot Air Motor
Heat pump

« QT Short Steam Circuit Stirling » simultaneously improves
both 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 much deeper vacuum that the cooling of a gas.

Up to 16 times more power than a Stirling piston engine
with 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 other Stirling 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 areas
where it will expand (evaporate) and produce a torque which moves it
 into the followings quadrants where it is cooled (condensed) again, and so on.
This rotation is provided by two opposed closed gas circuits working simultaneously
 on the Stirling thermal engine principle
(mechanical work produced by a closed fluid circuit simply from a constant heat 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 respective quadrants.
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 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 conductivity
and 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 Pump 
Driving 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 physical location,
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


4 pole Quasiturbine Stirling concept
The figure shows arbitrary angular lengths and positions of the hot and cold zones.

An alternative geometric arrangement would be to use an enlarged, flat, engine cover 
on one side as a cold plate linked to the corresponding cold radial zone,
and another enlarged, flat, engine cover on the other side as a hot plate linked to the corresponding hot radial zone.
This would give a sandwich-like compact-disk engine with wide, flat exchanger surfaces
particularly appropriate for solar free-space applications (with the shadow side cold).

An electricity generator with magnets can be incorporated 
into the Quasiturbine core to make the system a sealed unit.
Furthermore, due to high torque continuity resulting from the 16 pulses per revolution,
the Quasiturbine Stirling without a controller can provide optimum sinewave electrical output
without risking over-modulation of engine RPM, or stopping engine rotation at the instant of peak power.

Why is the Quasiturbine Stirling superior to conventional Stirling? 

The regenerator: 
The Stirling engine is able to produce mechanical energy from a constant heat flow, which the open Otto Cycle engine cannot do; furthermore, the Stirling has no intake and no exhaust. The regenerator is not mandatory in the Stirling engine, but when the gas flows alternately from cold to hot to cold... in the Stirling piston engine, the regenerator is a temporary heat storage aimed at increasing "thermal efficiency" with free-energy preheating and precooling. This may look good on the thermal balance sheet, but it is not so good for mechanical energy output because the regenerator adds an extra volume in the chamber (increasing the total gas mass). Any preheating and precooling increases the chamber charging pressure before TDC, and this is mechanically counter- productive for the piston (gas chamber loading requires less mechanical energy in the absence of preheating and precooling, which makes the regenerator less effective than one may think). Power increases as gas temperature differences increase in the chamber between the cold gas TDC intake and the hot gas BDC end; which means, from a mechanical point of view, that the gas should get the coolest possible entering the hot chamber, and the hottest possible entering the cold chamber (as in the Quasiturbine). Sure, the regenerator lowers thermal energy consumption, but it also lowers mechanical output, with limited effect on total efficiency. It should be noted that the problem is not with the regenerator concept or with having it in the system, but with the time frame in which it works, and also with the extra chamber volume it often adds to the pressure system. The regenerator adds to time constants in the process and lowers the maximum engine speed. The lack of a regenerator in the Quasiturbine is not for space/weight/power density considerations, but because there is never any back flow since the gas is progressing forward all the 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 and thermodynamics has failed, until now, to discover the ingenuity and the simple principles of the Quasiturbine. 

Thermal transitional effect ( "hot and cold" losses):
The fluid (gas or vapor) 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. It is important to notice that heat exchange is done radially, and not by convection 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 facing the next chamber side temperature plate. For this reason, the temporary coexistence of the fluid in the two chambers during transitions is not a thermal waste at all.

Torque continuity, RPM and Power: 
The Stirling cycle produces pressure variations seen by the piston alternatively as pressure and vacuum. In good working condition, the Stirling piston is pushed during gas heating and pulled during gas cooling, but those two forces never act on the piston at the same time. The resulting instantaneous torque on the piston is more constant (but less powerful) than in the internal combustion engine because it has 2 positive contributions of torque of about 90 to 120 degrees duration each per revolution - that is, one push and one pull. For each revolution of the Quasiturbine rotor, each one of the 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 instantaneous torque fluctuations, increase the power density, and remove the need for a flywheel (substantially reducing the engine weight and size even further). Because each Quasiturbine pivoting blade goes through 2 pushes per revolution 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, so that about the same RPM can fairly be expected. Consequently, based on equal chamber volume, a Quasiturbine Stirling rotor will produce up to 16 times more power than a piston Stirling (8 times due to the geometrical frequency, and 2 times due to the RPM), hopefully with less than 16 times the heat flow, and this does not take into account other valuable improvements like the elimination of inter-chamber tubing connections which will greatly increase the maximum pressure and vacuum.

The inter-chamber tubing connections:
The conventional Stirling engine needs inter-chamber connecting pipes to carry the gas to and from the cold and hot areas (displacer-side spacing plays the same role). Those pipes are passive extensions of the compression chambers, and since they are kept at a near-constant intermediary temperature, their gas content attenuates rather than actively contributes to the pushing effort. The Quasiturbine Stirling concept has no need for such interconnecting 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 the regenerator, which is quite imperfect in other Stirling engines anyway. It is the purpose of the Stirling to work by bringing the most possible heat by gas absorption from the hot area to the cold area. The Quasiturbine concept does it both frequently and without a regenerator - both sources of its higher power density. More heat moved by gas absorption equals higher engine power output. Furthermore, one should remember that when parallel surfaces move past one other, gas trapped between them will tend to roll in the direction of the moving surface, due to its adherence to the two surfaces, which ensures that when the gas comes up in the new zone in the following chamber it is essentially attached to the pivoting blade surface. This roll effect is so important in the Wankel engine that a second sparkplug is needed in the back chamber area to prevent combustion squelching. This roll is less important in the QT, but it contributes to convective heat transfer within the chambers.

Quasiturbine Steam-Circuit Stirling engine: (Quasiturbine Short-Steam-Circuit engine - Phases change mode?) To increase the heat flow transfer rate, 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 cold zones. This requires only a small quantity of liquid water, which the centrifugal force of the Quasiturbine rotation can maintain permanently in contact with the perimeter for an optimum heat transfer. Ultimately, this option could also be considered 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 the intermediary insulation has low thermal conductivity, and that the lateral engine sides and the pivoting blades are made of ceramic of very low thermal conductivity (or of conducting material coated with insulation).

2) Let's assume that the average gas temperature fluctuation in each chamber is 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 kept under 50 degrees C (a 50 degree C rise to account for gas temperature discontinuity at the surface and the gradient within the cold plate), and the hot zones are kept over 600 degrees C (a 200 degree C drop to account for gas temperature discontinuity at the surface and the gradient within the hot plate). This may also consequently require that the burner temperature be of the order of 1000 degrees C (an advantageous high temperature permitting to burn dust and solid particles responsible of Smog).

3) Let's assume that these temperature fluctuations (and corresponding pressures) are produced at the optimum angle in stationary regime operation, which means approximately when the ends of the pivoting blades are at the limits of the hot and cold zones. This may require that the thermal quadrant separation insulators be placed at a shifted angle (positive or negative, to be calculated by engine computer simulation) in reference to the rotation, so as to compensate for the thermalisation time lag due to the delay of heat transfer. The thickness of these inter-chamber insulators may also be adjusted to minimize the transitional thermal effect between the different temperature zones, mainly during pressure increase where the gas may slightly flow back into the insulation area. Before initiating a thermal transition zone, one can reasonably suppose that the gas is thermalized with its facing stator surface, and when the forward section of the pivoting blade passes the insulator toward the next thermal zone, the thermal variations occur only in this forward section, the section behind the separator insulation being always thermalized to its previous environment.

4) Lets assume that the gas thermalisation time constant permits each chamber to go through 24 thermalisations cycles per second. Since each chamber accomplishes 2 cycles per revolution, this give 12 revolutions per second, 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, and generally with helium) in the chambers (square configuration in order to have the same quantity of gas in each of them, or making use of check valves in the 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 exiting rotating shaft of the Quasiturbine, which a standard seal will easily make leak proof. On the other hand, this sealed enclosure could contain oil for lubrication, 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 fluctuations mentioned in 2) will produce by themselves average pressure fluctuations from Pmin = 1.33 P0 (bar or Atm.) to Pmax = 2.33 P0 (bar or Atm.), a simple ratio of absolute temperature, meaning a pressure differential between chambers 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 total engine power produced will be (a good way to rapidly control the output power, rather than by acting on the hot temperature zone, assuming an access to the chambers by the central region of the Quasiturbine via check valves in the pivoting blades).

7) Stirling engines generally operate with low compression ratios, even if they respond simultaneously to a thermal compression ratio and a geometric compression ratio (both are time variable, and the product of both ratios gives the real ratio). In fact, it is probable that little gain can be made by selecting a geometric compression ratio which would raise the gas temperature by adiabatic compression behind the temperature of the hot zones (except for accelerated heating by gas density and proximity effect, which would make it possible to achieve higher RPM). For the present calculations, we suggest putting aside the effect on efficiency due to the geometric compression to compensate for various losses still little studied. Note, however, that the Quasiturbine Stirling permits much higher compression ratios than the piston engine, and consequently less gas mass, which improves efficiency. 

8) Heat flow bottle neck: Heat flow is like water in a pipe network: the maximum flow is controlled by the bottle neck element, and a good efficient design is made of a sequence of elements having equal flow capability at full power, no more, no less. In thermal gas-solid devices, this is further complicated by the gas contraction-expansion effect (ignoring radiation) by which a gas flow is more efficient to heat a cold object (on which the hot gas is attracted by contraction) than to cool a hot object (on which the cold gas expands away). Reciprocally, an object is more efficient to cool a gas (which hot gas is attracted by contraction) than to heat it (which cold gas expands away). Consequently, heat exchange flux between a solid and a gas shows a diode effect, which induces an hysteresis effect in the reversibility. The proper argument applies here on the outside of the Quasiturbine-Stirling, but more critically inside, where the transition from a cold chamber to a hot chamber will increase the pressure and produce a small reverse flow into the cold behind chamber, which will demand a relatively longer angular hot pole. Conversely, a transition from a hot chamber to a cold one will reduce the pressure and produce a small forward flow which will accelerate the cooling, requiring a shorter angular cold pole for the same heat flow. Such optimization will make a better performing design, but will destroy the reversibility, for which another optimized machine should be designed.

Lets apply these hypotheses to the case of the Quasiturbine QT400: The Quasiturbine QT400 model (400 cc per chamber) has a rotor diameter of 28 cm (11 in.) and a thickness of 10 cm (4 in.), each chamber having a maximal volume of 400cc.. The internal surface of the hot zone (same for the cold zone) 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 the same for the total cold surface. About the suggested design, the cold area is liquid cooled while the hot area is heated through hot gas contact. Notice that the external engine hot area extends on the exterior over the cool area to increase chimney gas contact (which can still be further doubled by the use of fins). The diameter of the stator exterior is about 22 cm (8 1/2") and can be extended 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 thermal flow to produce 50kW mechanical with a 25% efficiency will be 4 X 50kW, which corresponds to an exterior heat flow at atmospheric pressure of 80 Watts/cm2 (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 6 bar or Atmosphere internal pressure would theoretically balance the external atmospheric pressure gas conductivity. With an absolute pressure differential or 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 or Atm.) 
Taking into account the approximations and the security factors, a first order calculation like this one allows us to establish the possibility of producing, in the said conditions, more than 50 kW mechanical or electrical by pressurizing the 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 Stirling could be more pressurized (certain Stirling engines reach 200 bars ou Atm and more), and so produce more power. Because the entire rotor is pressurized, the roughness constraint due to pressurization affects mainly the engine casing (the roughness constraint on the blades depends for its part of the relative pressure fluctuation from the chambers). However, it is interesting to note that the thickness of the Quasiturbines (and other rotary engines) in internal combustion mode is limited by its ability to extract the heat from the rotor centre. However, in pneumatic, steam or Stirling mode, the engine is thermalized 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 more linear, more efficient heat exchangers, and allowing production of still more power 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 the Quasiturbine, and a vacuum in the other cold half?
Quasiturbine Stirling with 2 poles (a hot half, other half cold)
would certainly worth a study to validate this possibility... (?)

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 of cooling the hot gas into a cold quadrant, move it from the hot-BDC into the cold-BDC chamber of a cold Quasiturbine located nearby, and when the gas has cooled to cold-TDC, move it back to the hot-TDC Quasiturbine. This will work, but the back and forth flows could still be one way
(without regenerator), which is again not appropriate for "regenerator" fans! However this Dual Quasiturbines configuration is not likely to raise the power density or the efficiency(?), because it will introduce holes and maybe pipes as passive volumes 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 to each other
(which makes the chambers 90 degrees out of phase) on the same common shaft,
and permitting the gas to flow back and forth between those two Quasiturbine chambers, either through a regenerator or not.
The Stirling 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 the rotating shaft from -45 to +45 degrees in the other Quasiturbine,
it produces in the latter a net variation of volume "null".
The volume added with the 2 coupled chambers being effectively modulated
between approximately 1/2 chamber and 1 1/2 chamber, varying little during the first 45 degrees, and much thereafter
(Note that the short circuit concept allows variations of volume of 0 chamber with 1 chamber,
and offers a stronger compression ratio)...

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.
The Quasiturbine Aviation page http://quasiturbine.promci.qc.ca/QTAviation.html proposes a Brayton cycle where two distinct Quasiturbines side by side on the same 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 present Stirling Dual-Quasiturbines concept).

 

Quasiturbine Stirling and Short-Steam-Circuit engine efficiency considerations

Stirling engines use a closed chamber (cylinder and piston) with a fixed amount of compressible fluid (no intake or exhaust). 
This confined gas is alternatively moved from the hot to the cold end of the cylinder
(generally by using a displacer object free to move within the chamber and taking the place of the gas),
producing an alternative expansion-contraction pressure variation which does drive a piston on a relatively short course.
This engine converts a constant heat flow from the hot to cold end of the cylinder into mechanical work 
with a superior potential efficiency since it does not exhaust any residual thermal or mechanical energy, 
but it is very limited in total power output density in weight and volume.
However, it can be combined with hydraulic engines to produce impressive power where power density doesn't matter. 
Since the gas is moved sequentially rather that alternately from the zones of different temperature,
the Quasiturbine Stirling is exempted from the need of a regenerator (not necessarily in the case of two Quasiturbines), 
which increases its efficiency and power output through an increase in RPM
because preheat and precool increases the chamber charging pressure before the TDC, which is mechanically counter-productive.
The Quasiturbine Stirling engine moves the gas around very efficiently, 
with a higher compression ratio (smaller gas mass), and allows for more power 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 is essential to reduce the time-losses in an engines (to reduce the idle periods). In all Stirling concepts, there is an obvious considerable loss of time when moving the gas which is often spread out over more than 90 degrees of shaft rotation, shortening the push and creating a backpressure. Whereas the researchers unanimously seem to carry their attention on the use of regenerators, we believe that the improvement of Stirling passes rather by an increase in the speed of the gas movement between the cycles of relaxation and contraction, and the suppression of regenerator (and yes!). Several refuse to understand that at the time of moving gas, larger are the variations in temperature and more brutal is the transition of gas between the heat and the cold area, higher the output will be. Output efficiency does not come from the regenerator, but from the speed of this gas movement,
which must be improved in all Stirling concepts
(Note that the movement of the displacer does not require in theory energy,
and how its acceleration does not consume anything theoretically!).

Although the Quasiturbine Stirling shows astonishing characteristics, it is the short steam circuit concept which offers most brutal transformation and makes it possible to anticipate a spectacular effectiveness. Indeed, its contour seal is scraping condensation droplets on the cold part (of water or others liquidate) and brings them brutally on the hot part, creating an extremely fast transition, highly beneficial to the effectiveness.

We believe these comments somewhat useful to understand the effect and the limitations of the Stirling engines,
even if it is sometimes inevitably necessary to accept limitations!

 

Combined heat cycle with Quasiturbine Stirling engine
in “GHG Alberta Solutions Showcase Newsletter”
http://quasiturbine.promci.qc.ca/GHGAlberta0205.html 

Stirling Hybrid Vehicle
Applications 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 Locomotive
See the section Quasiturbine Hydraulic Motor at
quasiturbine.promci.qc.ca/QTHydraulique.html

Non-stop nuclear Quasiturbine-Stirling for vehicle
which 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 of
Stirling Engine Society:
UK - http://www.argonet.co.uk/users/bobsier/inde.html 
USA - http://www.sesusa.org 

Model under development, only
RESEARCH APPLICATION PROTOTYPES
are available at this time.

 

Questions

The matter of heat transfer should be well assessed. Considering the details given 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 power thought 2500 cm2 (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 the pressurized gas from the two hot surfaces totalizing 400 cm2 (64 sq. in.)?

c) From the rotor: Can the internal pressurized gas move this heat flow from the 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?

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 realistic values.

 

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 be trapped. 
For example, avoid the following concept (used by the author as exam question for his engineering students!):

 

 

Be careful also when you make comparison between the Quasiturbine Stirling Cycle 
and the "Brayton Cycle" (also known as Joule Cycle) of the turboreactors. 
http://www.fas.org/man/dod-101/navy/docs/swos/eng/62n1-16/sld003.htm
Brayton Cycle uses the intermediary transformation of pressure energy into kinetic energy, 
which allow later the kinetic energy recovery at the same pressure that the chamber intake. 
Remember that the Quasiturbine is pressure sensitive and requires a higher pressure at intake than at exit, 
because it does not use kinetic energy transformation.
However, two distinct Quasiturbines on the same shaft sharing a common pressure in between may be linked and/or looped (?)
(If the first one is a cold high pressure low flow rate, the second one will have to be a hot low pressure high flow rate,
providing that some combustion comes in, to increase the flow at constant pressure like in turboreactor).
From a high pressure source like in jet airplane conditioning system, 
a Quasiturbine compressor could be linked with a Quasiturbine pneumatic motor through a cooling heat exchanger to act as a heat pump.

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Quasiturbine Vapeur Inc.
Casier 2804, 3535 Ave Papineau, Montréal Québec H2K 4J9 CANADA (514) 527-8484 Fax (514) 527-9530
http://quasiturbine.promci.qc.ca             quasiturbine@promci.qc.ca