Quasiturbine - Comparative efficiency with other engines
Discussion on the Minimum Gas Flow at operational RPM, Load factor, Gas Expansion,
Total engine output and Residual pressure energy lost
All the following is within the Carnot efficiency rule.
This discussion is about geometrical or mechanical pressure energy loss in the flow or exhaust of the four most common engine concepts: Piston, Turbine, Wankel and Quasiturbine. It is not about thermal energy lost, but one has to know and remember that the gas are thermodynamically cool down during the expansion process, so that the exhaust thermal energy is much less than thermal fuel combustion energy,
the difference being hopefully efficiently converted into mechanical energy?
Notice that some piston steam engine preheat the piston in compression
with some exhaust steam to increase the efficiency,
which is not needed in the Quasiturbine since the exhaust stroke is the steam compression stroke,
and is in great proximity as the exhaust stroke become without any delay an expansion stroke.
The energy of the compression and expansion strokes
Some people tend to believe that engine compression stroke is an engine energy lost,
which it is not, since this stored compression energy is largely recovered during the following power stroke.
Notice also that if we consider the three equal "early, mid and late" piston expansion volume zones,
they all produce under constant pressure the same amount of energy,
since the angular shaft displacement is larger in early and late volume variations.
However, the torque will be highly modulated, being fare superior in the mid stroke.
Square torque pulse like in the Quasiturbine produces the same energy with a more constant torque
and require a relatively less robust machine, since robustness is dictated by the peak torque.
Adiabatic versus isothermal expansion
When a compressible fluid is compressed, its temperature increases, and conversely when it expands, it cools itself.
Gas cooling during expansion is not a good thing,
because it reduces the pressure in the expansion machines (positive displacement), and lowers the gas speed in turbines.
To get the most power out of a machine (not necessarily to get more efficiency),
one likes to add heat to the expanding gas,
and if this is not possible in the process, the expansion is split in several stages (like 2 and 3 stages steam turbine).
One must understand that the extra power obtained this way is not free,
since heat has to be supplied, but it does give a better output per pound of engine.
What is nice about internal combustion engine,
is their ability to provide the maximum heat by combustion while the expansion is actually occurring,
something no other gas compressible engine can do easily! (this excludes hydraulic engine).
Like pneumatic / vapour Quasiturbine includes two circuits, these circuits can
be as desired fed in series by connecting the exit of the first room to the entry of the second.
While placing an exchanger on this conduit one can add heat in an attempt
to make that the total relaxation in the engine approaches an isothermal relaxation.
In this case, the differentials of internal pressure is distributed between the 2 successive chambers.
In the conventional turbines, one often makes such an intermediary heating
in order to increase the total power output of the machine, without necessarily increasing the efficiency.
In the case of Quasiturbine, the connection in series reduces inevitably the specific power
but can increase the output if intermediate heat is available free,
as in the case of atmospheric heat in pneumatic mode.
The recourse to the series mode can be of interest in the case of strong pressure
where the relaxation produces a strong cooling, but presents little interest
with Quasiturbine with the low pressures, let us say lower than 50 lb/po2 (psi).
If the differential of pressure is considerable,
the volumes and displacements involved in the initial relaxation are much less than with the final relaxation,
so that the machine in initial phase must be of smaller dimension
(let us say for a relaxation from 600 to 300 psi) that for the final phase (of 300 to 0 psi).
If the use of a single machine requires an initial pressure reduction,
this initial loss of pressure in a regulator is not converted into mechanical energy,
but in thermal cooling and kinetic energy, the last one attenuates obviously adiabatic cooling...
Because volumes and displacements in final phase are more important,
the same differential of pressure on this level produces more energy at a higher pressure.
In other words, to extract the maximum energy from a very high pressure,
one would need a cascade of machine starting with smallest, each one reducing the pressure a little and feeding the following one...
The old steam engines use 3 such stages (or more stages in the case of turbines),
Titanic had steam engines using 4 stages of relaxations...
MDI for its part proposes a pneumatic car with very high pressure using 3 stages with piston.
Nothing prevents from juxtaposing 3 Quasiturbines of different sizes to do still better!
In the case of a source of pressure which becomes exhausted with time like compressed air in cylinders,
the obvious disadvantage is that early stages would become useless as the pressure becomes less.
A high pressure tank cooled gradually when pour in an intermediate low pressure tank,
but it is at the entry of the low tank pressure that the relaxation is violent and where cooling is most considerable.
However, relaxation kinetic energy forces does not transform itself into mechanical work, but into heat,
thus reducing the net effect of cooling in the low tank pressure or in the regulator.
It is however not very wise to use the energy of pressure of high pressure tank
to heat the intermediate partially low pressure tank,
from where the interest to use multiple mechanical relaxations with heaters isobars between the stages!
Energy being proportional to the pressure time the volume, energy is weak after each relaxation even if there is pressure,
because volume is contracted and weak, and it is the heating which gives again the volume, and thus of energy
These multiple relaxations are profitable in the case of systems of several megawatts
(with high and constant initial pressure) having important operating time ratios,
but are more difficult to justify in the case of small vehicles asking for a few tens of kW only,
where the operating time ratio is half an hour per day, and of which high pressure of the tanks is not constant!
All this shows that higher the pressures are, and lower the temperatures are,
less the system of production / recovery is effective.
REMARK ON PNEUMATIC SYSTEM EFFICIENCY
An high efficiency pneumatic motor does not guaranty the high efficiency of the entire pneumatic system.
All gas heat up during compression and cool down during relaxation.
The cooling effect must not be under-estimate. As an example, a typical 200 bar (atm.) cylinder
empty adiabatically (without thermalization to ambient temperature) gives at the end an air so cold
that its volume is then a 1/4 of that of the air once back to the ambient temperature (isothermal relaxation).
In those temperature conditions at the entrance of a pneumatic motor, the efficiency is catastrophically low
and the lubricant solidified, increasing considerably the internal engine friction...
Generally, the reversibility of the compression - relaxation cycle reduces with an increase in pressure,
which favours for high efficiency consideration the use of the lowest design pressure possible.
The measurement of the exhaust temperature gives generally a good indication of the efficiency,
since the minimum of energy lost into the environment correspond to
an exhaust temperature equal (neither inferior, nor superior) to the ambient temperature.
This condition can be achieve by a slight heating (solar) of the gas before its entry into the pneumatic motor.
Quasiturbine makes much more relaxation if it is use
with a dominant restriction at the entries of the chambers, and not at the exhausts.
The openings of exhaust must then be larger than them openings of intakes,
so that the air leaves more easily than it does enter, and thus lowers of pressure in the engine.
In this case, Quasiturbine has less specific power, but because it makes more relaxation, it is more effective.
One can make more relaxation by still reducing access to the intake, without synchronization valve,
or by reducing somewhat the torque taken out of the machine.
Since the Quasiturbine rotates from pressure as low as 1/10 of atmosphere (bar) (one psi !),
one understand why the Quasiturbine is so well adapted to high efficiency system...
Steam versus pneumatic - Effect of the condensation
The pneumatic motor has no phase change during relaxation,
such that at the time of exhaust it must evacuate a large volume of gas,
while the phase change of the steam into condensate during the relaxation
reduces considerably the volume to exhaust (similarly to the adiabatic cooling in an internal combustion engine)
and help to increase the engine performance. To fully benefit of this effect,
it is advantageous to make a cut-off or a strangle of steam intake at mid-course,
to make certain that a relaxation and condensation occur in the chamber before the exhaust opening.
Zero Load factor high-revolution efficiency - Minimum Gas Flow at operational RPM
Some people tend to believe that a free running engine (from which we do not take power) require a very small fuel consumption used only to compensate for friction or internal energy dissipation. Let first explain why this is not true, and why a Minimum Gas Flow (or consumption) at operational RPM is needed
and vary from one an engine concept to an other.
Rotating any of the four engine concepts with an external power source will generate a gas flow (not obstructed) at engine intake and exhaust, confirming that engines are in fact pumping devices operated in reverse mode. This flow will increase with the RPM and will also depend of the engine concept. Assuming four engines concepts of equivalent power but having different operational RPM, one will notice that the highest flow will be produced by the conventional turbine, because its is aerodynamically working at very high RPM. Next down will be the Wankel, then the piston and the Quasiturbine on the same level (At the same RPM, the Quasiturbine will pump 4 times more than the piston, but since its operational RPM is four time less, they compare exactly). If we want to self-run those 4 engines concepts at operational RPM, the reversibility principle will required that we provide an equivalent reverse Minimum Gas Flow at operational RPM in order to maintain the "free running" (without taking out any engine power - zero Load factor). Making this Minimum Gas Flow at operational RPM from pneumatic, steam or internal combustion is energy consuming, and seriously limit the low-power (zero Load factor) high-revolution engine efficiency, because this minimum flow energy is in pure waste. The conventional turbine is the engine which requires the highest gas flux (and consequently the highest consumption) just to maintain its free operational RPM (without producing any net energy), explaining why they are so fuel inefficient when not producing their full power. It must be understood that in order to actually deliver power, the flow must be increased from this Minimum Gas Flow at operational RPM. Mechanically, the Quasiturbine flow case is the easiest to understand, because it is obvious that to maintain the revolution, the Minimum Gas Flow at operational RPM must have the same velocity as the tangential blades turning around the Saint-Hilaire confinement profile. This discussion explains why for efficiency reason, an engine should never be selected more powerful than required. Idling (zero Load factor) a powerful engine always consumes more than idling a less powerful one. It does also explain why it is advantageous at low power to cancel down combustion on some of the pistons in order to increase efficiency.
Photo-detonation and Diesel versus cycle Otto
At low load factor, the intake depressurization of the Otto cycle dissipates power from the engine since the throttle valve is almost closed and the descending piston acts as a clogged vacuum pump against the atmospheric pressure, which vacuum is subsequently partially destroyed by fuel vaporization during the compression. Due to this effect, the engine in Otto cycle opposes to all RPM revolution increase (well known as the engine compression breaking) and this intrinsic resistance to speed augmentation is compensated by a constant and important fuel consumption. The photo-detonation mode does not use any throttle valve and accept without constraint all available air at atmospheric pressure (similarly as the Diesel, where the pressurization energy is restituted at the time of relaxation). For this reason, the efficiency at low load factor of the photo-detonation engine is twice that of the conventional Otto cycle, and considering that the load factor of a car is in average of about 10 to 15%, this is not a small difference (saving is still superior in the traffic jams...). See http://www.vok.lth.se/CE/research/HCCI/i_HCCI_uk.html
Compression ratio and parasite volume - Effects on engine efficiency
Pneumatic and steam engines get their pressure from an external source,
and it is obvious that any residual chamber (charging volume) within the TDC top dead center position
will have to be pressurized in pure lost before the pressure can make work on the piston itself.
For efficiency reason, one like those engines to have a very high geometric compression ratio 100:1 or higher.
Even if less obvious, the situation is alike with the IC internal combustion engine,
because from the pressure point of view, the TDC combustion chamber is a parasite volume,
which has to be pressurized in pure lost before producing any work on the piston itself.
To be more efficient, the combustion chamber must be the smallest possible,
which means the highest possible compression ratio.
To a certain extend, the Diesel engine does that, but looses the advantage of the uniform combustion.
However, there are other obstacles to increase the compression ratio.
In relation to mechanical limitation, the stress is proportional to the product ( Pressure X Time ),
such that if the compression pulse can be made shorter,
much higher compression ratio can be achieved without increasing the stress and fatigue on the engine.
This is exactly what the Quasiturbine does by having a pressure pulse at the tip which is 15 to 30 times shorter!
In relation to self-firing or photo-detonation, piston can not permit higher compression ratio
because such a timing is not controllable, and can not be postponed until the piston fall down.
The Quasiturbine fast raising and falling pressure pulse guaranty that the photo-detonation occurs at the right time.
In relation to fuel pollutant generation, piston does confined the gas for too long,
and allows the chemistry of NOx to be completed.
The Quasiturbine short confinement time does not allow NOx to be generated.
The short Quasiturbine pressure pulse reduces the confinement time,
but also the gas thermal exchange with the engine block,
and consequently leaves more heat into the expanding gas, which increasing the thermodynamic efficiency.
The Quasiturbine IC end result goes toward an engine in photo-detonation mode,
having a compression ratio of 30:1 or higher, using low octane gas, producing no NOx,
benefiting from fast radiation photo-detonation combustion process
(Knocking - Leaving extra combustion time to eliminate all un-burnt hydrocarbon),
with the advantage of uniform combustion without any synchronized intake or firing sparkplug,
being more efficient, and furthermore multi-fuel capable, more compact,
lighter, high torque at low RPM, 20 times less noisy, zero vibration...
Pushing gas versus expanding gas
Conventional turbines and all positive expansion machines (including the Wankel) do have a similar exhaust residual mechanical energy lost dilemma particularly sensitive in fluid flow engine mode when using an "external compressed fluid (air, steam...) reservoir", a dilemma which does not exist with incompressible (hydraulic) fluids flow. It does take energy to compress gas, but positive expansion machines do take only energy from the pressure action, careless how much energy is actually stored internally in the pressurized pushing gas in the expansion chamber, which is later exhausted. Let explain differently : If a piston is released after it has compressed air, compression work is very efficiently given back in energy, and the final differential expansion pressure is zero like at the starting point (which is not the case when using external gas pressure reservoir). This means that using gas (steam) from a compressed reservoir, optimum expansion efficiency required to inject only a certain quantity of loading pressured air (steam) at Top Dead Center, such that the final exhaust expansion pressure differential will be small (which do not means a null exhaust flow). Doing so, the gas in the expansion chamber will push with a reduced average pressure, and the total engine output will not be the highest (since pressure decreases as 1/x, the average pressure will be much less than half of the maximum). Similarly, conventional turbine convert tank pressure and expansion energy all at once, and trying to take out too much power from a conventional turbine will lead to blades stall and very inefficient regime. By maintaining the high pressure injection for a long time period (the expansion is then replace by a more constant pressure push), the total engine output power will increase substantially and so will the final exhaust pressure with substantial decrease in engine efficiency. Theoretically, mechanical efficiency (not thermal) at constant and continuous maximum injection pressure of compressible gas fall quite rapidly with the exhaust pressure differential, from 80% at 4 atmospheres to 60 % at 120 psi, and to 30 % at 500 psi (not to be confused with thermal cycle or internal combustion efficiency). Said otherwise, to maintain near 100% mechanical efficiency (extracting reservoir pressure energy and the total enclosed expansion energy with a zero exhaust final pressure, and ignoring thermal), the total Quasiturbine (or most positive expansion machine) power would have to be reduce to 1/3 of its maximum power at 7 bars (120 psi), or to 1/8 (which only double the engine size) at 33 bars (500 psi). Active or passive flow control (power control) using restrictions (and intake cavities) can be designed to limit the injection pressure duration when needed (The Quasiturbine restriction being sufficient), and make sure that gas expansion effectively occurs for a better efficiency in all engine. Internal combustion engines work from a limited combustion gas volume which actually expands and produces a similar substantial residual exhaust pressure mechanical energy (and thermal) lost
(efficiency also decreases as the load or the internal piston pressure increases).
This is not however a concern with incompressible fluid like water or oil in stable phase (viscosity may be ?),
since it is not possible to store significant internal pressure energy in such a liquid.
Never the less for similar applications, the Quasiturbine has the highest efficiency compared to any other engine.
Always remember that all engine efficiency fall with increasing exhaust pressure and temperature (output power).
Efficiency improvement by Asymmetric compression ratio !
To increase piston efficiency, the intake valve can be keep open late which reduces the amount intaked,
and the compression ratio experienced by the mixture.
However, during combustion, the mixture experienced a high compression ratio equivalent
since the expansion occur on a larger range.
With the Quasiturbine, this is possible without any valve, just by making the intake port to a late angle !
Compression ratio becomes say 10:1 at intake (spark plug needed) and 20:1 at combustion...
However, as efficiency goes up, specific power goes down... Up to the user to decide...
This is called either Atkinson or Miller Cycle... See definition from http://www.wordiq.com/definition/Engineering
Atkinson cycle :
The Atkinson cycle engine is a type of Internal-combustion engine invented by James Atkinson in 1882. The Atkinson cycle is designed to provide efficiency at the expense of power. The Atkinson cycle allows the intake, compression, power, and exhaust strokes of the Four-stroke cycle to occur in a single turn of the crankshaft. Owing to the linkage, the expansion ratio is greater than the compression ratio, leading to greater efficiency than with engines using the alternative Otto cycle.
The Atkinson cycle may also refer to a four stroke engine in which the intake valve is held open longer than normal to allow a reverse flow into the intake manifold. This reduces the effective compression ratio and when combined with an increased stroke and/or reduced combustion chamber volume allows the expansion ratio to exceed the compression ratio while retaining a normal compression pressure. This is desirable for good fuel economy because the compression ratio in a spark ignition engine is limited by the octane rating of the fuel used, while a high expansion ratio delivers a longer power stroke and reduces the heat wasted in the exhaust. This makes for a more efficient engine. Four stroke engines of this type with forced induction (supercharging) are known as Miller cycle engines.
Miller cycle :
In engineering, the Miller cycle is a combustion process used in a type of four-stroke internal combustion engine. The Miller cycle was patented by Ralph Miller, an American engineer, in the 1940s. This type of engine was first used in ships and stationary power-generating plant, but has recently (late 1990s) been adapted by Mazda for use in their Millenia large sedan. The traditional Otto cycle used four "strokes", of which two can be considered "high power" – the compression and power strokes. Much of the power lost in an engine is due to the energy needed to compress the charge during the compression stroke, so systems to reduce this can lead to greater efficiency.
In the Miller cycle the intake valve is left open longer than it normally would be. This is the "fifth" cycle that the Miller cycle introduces. As the piston moves back up in what is normally the compression stroke, the charge is being pushed back out the normally closed valve. Typically this would lead to losing some of the needed charge, but in the Miller cycle the piston in fact is over-fed with charge from a supercharger, so blowing a bit back out is entirely planned. The supercharger typically will need to be of the positive displacement kind (due its ability to produce boost at relatively low RPM) otherwise low-rpm torque will suffer. The key is that the valve only closes, and compression stroke actually starts, only when the piston has pushed out this "extra" charge, say 20 to 30% of the overall motion of the piston. In other words the compression stroke is only 70 to 80% as long as the physical motion of the piston. The piston gets all the compression for 70% of the work.
The Miller cycle "works" as long as the supercharger can compress the charge for less energy than the piston. In general this is not the case, at higher amounts of compression the piston is much better at it. The key, however, is that at low amounts of compression the supercharger is more efficient than the piston. Thus the Miller cycle uses the supercharger for the portion of the compression where it is best, and the piston for the portion where it is best. All in all this leads to a reduction in the power needed to run the engine by 10 to 15%. To this end successful production versions of this cycle have typically used variable valve timing to "switch on & off" the Miller cycle when efficiency does not meet expectation. In a typical Spark Ignition Engine however the Miller cycle yields another benefit. Compression of air by the supercharger and cooled by an intercooler will yield a lower intake charge temperature than that obtained by a higher compression. This allows ignition timing to be altered to beyond what is normally allowed before the onset of detonation, thus increasing the overall efficiency still further. A similar delayed valve closing is used in some modern versions of Atkinson cycle engines, but without the supercharging.
For a thermal energy efficiency superior to 50% ! (theoretical)
Since water requires an important quantity of latent vaporization heat
(which is not generally recover in the condenser or in the atmosphere open circuit),
operation with saturated steam will always gives low efficiency (5 %) (unless with a cogeneration application),
because of the important volume of water which needs to be evaporated to maintain the pressure.
Even if the Quasiturbine can accept saturated steam,
it is not suitable from the energy efficiency stand point, that this steam stays saturated during all the cycle.
In fact, in all expansion thermal machine (the Quasiturbine being one of the most efficient),
increase in thermal efficiency is always links to steam overheating (without having to increase the pressure),
since then one gets the same pressure effect with less molecules,
wherein making a substantial reduction in the quantity of water needed to be vaporized
(... and saving of the corresponding latent heat energy, while some more calories are lost in the exhaust).
With an important overheating, the efficiency of the thermal steam engines can reach and even exceed 50% ...
(The overheating may occur in the steam pipes, or in the Quasiturbine itself).
In practice, a tuned conventional system can have an efficiency exceeding 20%, with direct drive and instant reverse.
Why does the piston steam engine save steam by cutting intake before the end of the stroke?
Because of the sinusoidal crankshaft movement, the piston produces most mechanical energy
in the central third of its expansion stroke, little at beginning and little at the end.
It would be nice to cut steam in the first stroke, but it does need to be filled so that the second third can push,
but the last third is 1/3 of the volume and produces little energy, so it does make sense to cut the intake and save steam.
Why is it not the same with the Quasiturbine?
Because the Quasiturbine is not sinusoidal, and transform pressure into mechanical energy
much earlier and much later as well in the stroke, so that cutting intake will reduce power and make insignificant savings.
This last comment also applies to pneumatic engines.
... No more need for very high pressure steam to be efficient!
The conventional steam turbines require very high pressure
in order to generate the high flow speed permitting the turbine to be efficient.
This is not the case with the Quasiturbine which is very efficient
at all pressures, all load levels and all RPM,
and can produce substantial power
with sustained intake pressure as low as 20 à 50 lb/po2 and at only 1800 RPM.
In those two cases however, the super-heated steam increases the efficiency of the steam cycle,
and the lower pressure operation may lead to larger equipments for the same power...
The Quasiturbine greatly reduces the station construction and operation cost,
improves substantially the risk and safety level,
and reduces the law constraints and the qualification needed from the employees.
Stirling engine efficiency considerations
Stirling engine uses a close chamber (cylinder and piston) with a fix 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 convert a constant heat flux 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 combine with hydraulic engines to produce impressive power where power density is no 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,
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 higher compression ratio, and allow for more power density.
Since there is no exhaust, they are very quite engines, and the Quasiturbine Stirling is further vibration free.
See: Quasiturbine Stirling Engine
Exhaust energy recovery (regeneration) - 2 Quasiturbine ports!
As shown, the engine efficiency falls as exhaust energy in pressure, speed and temperature increases.
Conversely, one can almost decide at design of the efficiency by fixing the exhaust initial exit pressure.
Near the BDC bottom dead center of the piston or the Quasiturbine blade, there is a short angular range
during which back pressure will not significantly affect the engine operation,
where exhaust speed can be recuperated into a turbo,
and pressure energy can be "regenerated" into a secondary pneumatic Quasiturbine.
Residual heat can eventually be recuperated though a Quasiturbine Stirling engine.
Because the exhaust of the Quasiturbine occurs on a substantial angular area,
by making one early exhaust port and one late exhaust port, efficient regeneration can be done
by a secondary Quasiturbine feed by the early exhaust port, while the late exhaust port exit to atmosphere...
This kind of exhaust recovery sequence is not possible with the piston machine,
and allows higher efficiency while maintaining exceptional specific power density.
Optimum efficiency: Load factor versus RPM
This discussion gives some engine considerations useful for efficiently integrate an engine into a given application.
There is not one simple solution and every thing is matter of compromises. Generally speaking :
- Select the smallest engine power suitable for the need.
- Lower the internal engine pressure will be, better the efficiency (be careful about this statement ?).
- Lower the RPM will be, better the efficiency (be careful about this statement ?).
- To be efficient, the Minimum Flux suggest to take the maximum power from low RPM, but then the higher internal pressure will lower the efficiency. To optimized the efficiency, increase simultaneously the Load Factor and the RPM,
such that the total relative lost (minimum flux + exhaust pressure) / (net engine output) is keep minimal.
- About conventional turbines, use them only at nominal design RPM, load and power.
- From the integration point of view,
the Quasiturbine looks somewhat like a super-efficient very high torque low RPM piston engine...
Quasiturbine - A better energy efficiency
In relation to intrinsic effectiveness of the internal combustion engines in general, the energy of the fuel loses itself mainly on 5 levels: in consumption interns accessories of the engine (like the cams), in incomplete combustion, in the heat flow to the engine block, in the pressure (speed) and after-heat of exhaust fumes, and thermodynamic output limited due to the constraints of temperature and pollution. Quasiturbine improve each one of these considerations by not having any internal driven accessory, by allowing a thermal and photonic combustion more complete, by limiting the heat flow to the engine block by a shorter containment, by better exhaust fumes cooling by adiabatic pressure drop, in tolerating a higher temperature of combustion by the absence of valves, and by reducing the production of pollutants by a shorter compression puslse not allowing the chemistry of NOx to be carried out. Rotary geometry allows moreover a reduction of the surface swept by joints, and thus of the friction. Moreover, the continuity of the flows at the entry and at the exit of Quasiturbine increases the factor of use of the pipes by a factor from 6 to 10.
Nowadays, the output or effectiveness of engines has impact which largely extend over the strict aspect kW (BTU), because efficiency cannot be dissociated from its context of operation and sound use. Quasiturbine intrinsic energetic efficiency is higher amongst other things by suppression of energy consuming accessories. The high output of Quasiturbine is also connected to each of the following elements:
Quasiturbine improves each of these elements with several regards, mainly because it:
- Thermodynamics (advantage resulting from the early and late extraction of the mechanical energy).
- Thermal (a flow of heat reduced towards the engine block).
- Friction (the product "friction X displacement" is lower than that of the piston).
- Accessories peripherals (a profit resulting from the absence of accessories: free of cams, valve...).
- Energy devoted to evacuation of the burnt gases.
- Power instantaneous peak (only 20% higher than the average, compared with 7 times for the piston).
- Little harmonic on the shaft (no need for crankshaft, nor of flywheel).
- Economy from absence of gearbox with fixed or multiple ratios (from 8 to 12 % of economy).
- Economy in durability (measured in a number of passages, the low revolution means an increase in durability).
- Effectiveness of intake (the piston has a poor sinusoidal intake characteristic).
- Economy within application (a lighter vehicle... mean economies over 10 years!).
- No additive in fuel (Quasiturbine asks for a less octane rate).
- Environment (saving in fuel and less NOX product).
- Vibration zero (source of billion $ of damage and corrosion).
- Economy of space (4 times less than the piston engine).
- Saving in weight (5 time less than the piston engine).
With a top engine torque at low revolution, the Quasiturbine does not need gear boxes with fixed or multiple ratios for the majority of the uses, meaning direct increases of the output, and an economy of consumption.
- Has less driving accessories to actuate, not valve, tumbler, push rod, cams, pump oil...
- Better management of time and offers a better operating time ratio to its components. At the time of the relaxation, Quasiturbine allows an earlier and later extraction of the mechanical energy.
- Offer the best thermodynamic behaviour because of shorter impulses of pressure, which limit also the production of NOx.
- Possibly to use carriages which make it possible Quasiturbine to generate strong asymmetry on its perimeter, and to thus compress the mixture in shorter angular zone, for then slackening it on a greater angular area.
- Operation in continuous flow which improves the intake characteristic, which can to be even prolonged in the following cycle without fearing backpressure.
The photo-detonation Quasiturbine suppress all interest and need for hybrid vehicle concept,
since even a powerful Quasiturbine engine would have a small low regime efficiency penalty !
The relation between the hybrid vehicle concept and the Quasiturbine photo-detonation engine.
The hybrid vehicle concept is interesting with the present conventional internal combustion engines
because it is more efficient to run a 20 kW engine at full 20 kW at all time
(despite the inefficiency, weight and cost of the storage system), than to run a 100 kW engine at 10kW most of the time.
Notice that the present day hybrid vehicle offers about 50% fuel saving, ignoring the hardware energy investment !
But why is it so ? Why is it that if you lower the output power of an engine to 10%, the fuel consumption is only reduced to 25% ?
With Diesel engine, it has to do with the non homogeneous jet fuel mixture which requires more fuel to fire at idle.
With the Otto gasoline cycle, it has to do with the intake manufold depressurisation,
which makes idle engine to work hard against the atmospheric pressure...
These piston engine limitations can be overcome by the photo-detonation Quasiturbine engine.
It is not an easy road, but it is for sure an impossible road for the piston engine.
The shorter Quasiturbine linear-ramp-pressure-pulse allows and stands the very violent
but complete and clean photo-detonation combustion.
The photo-detonation engine has very little idle efficiency penality, which means that a 100 kW engine can be
efficiently and continuously used to produce only 10 kW of useful power, including on gasoline, diesel, or other fuels.
In this condition, there is no need to have an hybrid energy storage system, since the energy
you do not need is kept stored in the fuel tank!
The vehicle still can be electrical, but now with an all regime efficient high capacity modulated
power generator instead of a battery storage...
More on detonation at : Engine Problematic and Detonation Engine
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