Quasiturbine> Theory> Hybrid Differences

 


Few seems to know the reason and the potential limit of Hybrid Concepts?
Hybrid is a complicated way to harvest part of the piston engine losses
that Quasiturbine detonation engine simply does not lose...

Theory - Quasiturbine versus Hybrid


Hybrid versus Detonation

In an interview on December 15 2004, Myron D. Stokes of eMotion!Reports wrote (from the press Release):

... Questioned about the Toyota Hybrid System www.toyota.com  and the PAICE Hyperdrive System www.paice.com , the president of Quasiturbine Agence Inc., Dr. Gilles Saint-Hilaire explained that " These are viable approaches for the near term because they are some of the best practical ways to avoid the low-power-efficiency-penalty of the today high power vehicle engine, used with only 15% average load factor. But getting extra efficiency this way requires additional power components and energy storage, with associated counter-productive increases in weight, space, maintenance, cost and environmental recycling process". However, in addition to the Otto internal combustion mode Quasiturbine www.quasiturbine.com , Saint-Hilaire expects a rapid development of the photo-detonation Quasiturbine in the next 5 years, taking full advantage of its unique short and fast linear ramp pressure pulsed properties (This "knocking" mode is almost impossible for the sinusoidal crankshaft piston engine to tolerate). Such a photo-detonation Quasiturbine, notes Saint-Hilaire, would have very little low-power-efficiency-penalty, would be more environment friendly as it would require low octane additive-free gasoline or diesel fuel, would be multi-fuel compatible, including direct hydrogen combustion, and would offer a drastic reduction in the overall propulsion system weight, size, maintenance and cost". This would tend to make the hybrid concept much less attractive long term, until such time when fully electric vehicles will efficiently "fuel" from the electrical grid." ... Complete Press Release at :
http://quasiturbine.promci.qc.ca/Presse/QTEmotionPR031217.pdf


Low Power Efficiency Penalty

The efficiency of a 200 HP gas engine falls dramatically when used at 20 HP, because of high vacuum depressurization needed in the intake manifold, this vacuum reduces as the power produced by the engine increases. The reason for modern hybrid concepts is to harvest this low-power-efficiency-penalty of today's high power vehicle engine, generally used with only 15% average load factor. This is a 50% fuel saving potential in transportation, of which about half could be harvested the hybrid way.

It is the main purpose of the hybrid car concept to avoid the low efficiency of gas engine at reduced power. However, detonation engines do not need intake vacuum as they intake all the air available, and mainly for this reason, efficiency stay high even at low engine power.


Hybrid Definition

Detonation and hybrid are two different means to harvest the low efficiency of reduced power piston engine, and both are compatible with efficient electrical (in-wheel) power train. Detonation engine is however a more direct and efficient way, and because the on board fuel is already a form of energy storage, detonation engine avoid to re-stock this energy electrically into batteries. The chemical energy stored in the fuel is degraded when chemically re-stored in batteries.

Lets make first a distinction between electric vehicle getting their power from electrical grid and the hybrid concepts. Advanced electric vehicles using powerful in-wheel digital motors and a set of high efficient batteries rechargeable from the grid, are not hybrid vehicles (having only one propulsion system). The idea behind such a vehicle is to benefit from the high electricity conversion efficiency of public utilities, instead of poor efficiency of onboard engine. This concept requires larger electricity storage than the Hybrids, and this is their deficiency today. Ultimately, Hybrid will have to measure to Quasiturbine detonation engine, which also will have to measure in efficiency to pure electric vehicles... However, the Quasiturbine detonation engine could continue to stay the supreme onboard generator for extending pure electric vehicle autonomy...

Hybrid is one way to avoid the lost of efficiency of powerful piston gas engine when running at low power, the Quasiturbine detonation engine being an other and better possibility. This is a 50% fuel saving potential in transportation, of which about half could be harvested the Hybrid way. But getting extra efficiency the Hybrid way requires additional power components and energy storage, with associated counter-productive increases in weight, space, maintenance, cost and environmental recycling process. For now however, the hybrid concept is attractive, until such time when fully electric vehicles will efficiently "fuel" from the electrical grid. ...

Hybrid means to have 2 or more active propulsion systems in series or parallel. Parallel concepts are the most complex and the less long term versatile, but the mostly used at this time, because engines can add up their power when needed. Serial concepts mean that only one propulsion system drives the train, supplied by one source or another. Serial must have total power at the wheel, but offers more versatility in term of energy storage and handling management.

Among the confusions about the hybrid cars, many believe that hybrid is mainly to allow regenerative braking ? It is not. Regenerative braking (electrical, pneumatic, hydraulic...) could be an added technology on vehicles, and is often self-included in hybrid concepts. Regenerative braking energy recovery is insignificant on the highway, little when the batteries are near fully charged, limited to soft braking (heavy braking exceeding recovery power capability), and none for now from the back wheels (still waste energy to standard friction brakes). It is however valuable in intense city driving, and is also of course an asset of most hybrid concepts. Regenerative braking system can exist independently from hybrid.


A Cascade of Savings

The paradox of today hybrid vehicle concept is: How much additional equipment can be added to a vehicle to reach the point where this equipment has worthless net saving effect in actual application?

Engine efficiency is a large domain of activity which extends far beyond engines. The presence of an engine in a vehicle adds accessories and weights which have to be carried by the power of that same engine (the net usable power is reduced by the presence of the engine itself). The presence of the engine is a necessity, but also a factor of inefficiency. The ideal vehicle would not bother to have an onboard engine! This shows that not only engine efficiency is important on the bench test, but must also reduce to the minimum its self-inefficiency in application. It would be worthless to have a 70% efficiency gas engine for mobile application, if such a 30 HP engine would weight 3 tons!

Because the Quasiturbine reduces the weight of typical vehicle power train by over 50%, it does not have to claim any extra efficiency on the test bench to be most valuable. Such a reduction of weight on the lifetime of a vehicle means substantial reduction in power demand, and consequently in fuel.


Engine Exhaust Heat Recovery

Recovering 30% of the engine exhaust heat would allow to exceed most hybrid efficiency performance. By placing a hot Quasiturbine into or around an engine exhaust pipe, and injecting pressurized hot water (steam keep in the liquid state for better heat transfer), some heat can be recovered into mechanical energy. A Quasiturbine Stirling or short steam circuit could do similarly! See: Engine Exhaust Heat Recovery with Quasiturbines


Electric - Combustion, Hybrid

In parallel concepts (most commonly used today), while the IC engine is at stop, the electric motor/generator can carry reasonable power demand. To provide extra power, or when the battery needs to be recharged, the IC engine and the electric motor generator are geared together. In serial concepts, electric motors (either central or in-wheel) provide all the train power at all time, either from the batteries, or from the batteries and the onboard generator together.

In these two concepts, battery storage capacity needs to be moderate, as they only intervene for peak power, and long run energy comes from the fuel tank. Regenerative braking (electrical, pneumatic, hydraulic...) could be an added technology on vehicle, and is often self-included in hybrid concepts.


Pneumatic - Hydraulic, Hybrids

A hydraulic hybrid vehicle uses hydraulic and mechanical components instead of electrical ones. A variable displacement pump replaces the motor/generator, and a hydraulic accumulator replaces the batteries. The hydraulic accumulator, which is essentially a pressure tank, is potentially cheaper and more durable than batteries. Hydraulic hybrid technology is being actively developed primarily in heavy vehicles like buses, trucks and military vehicles. Other hybrid concepts may also be developed.


Quasiturbine Over Hybrid

Detonation and hybrid are two different means to harvest the low efficiency of reduced power piston engine, and both are compatible with efficient electrical (in-wheel) power train. Detonation engine is however a more direct and efficient way, and because the on board fuel is already a form of energy storage, detonation engine avoid to re-stock this energy electrically into batteries. The chemical energy stored in the fuel is degraded when chemically re-stored in batteries.

The Quasiturbine has several intrinsic efficiency characteristics which add up and reduce the engine energy lost in several ways:

  • Because it does not have internal accessories to drive, like the piston cam shaft and valve train, additional energy is available to the end users.
  • Because of the shaping of the volume pressure pulse, the thermodynamic of the Quasiturbine can be far superior.
  • Because the engine weight is about 1/4 that of a piston, energy saving can be substantial in many applications.
  • Because the Quasiturbine is a high torque low rpm engine, much less or no transmission gears ratio is needed with corresponding efficiency increase.
  • Because the Quasiturbine can be made of large size, it is an efficient alternative to utilities for efficient energy conversion (steam) in electricity or from co-generation.
  • Because the Quasiturbine (AC model with carriages) has the potential to run in detonation mode, it will not have the low power penalty of the Beau de Rocha (Otto) cycle, which can provide a 50% energy saving in transportation application (much superior to hybrid concepts).

Multi-fuel capability is also an important efficiency factor permitting to use the most pertinent local combustible. Hydrogen high compatibility is also of consideration for the future.

So, the Hybrid Concepts have been developed to harvest the low piston efficiency at reduced power. If a new engine does not have such a penalty at low power, the Hybrid Concept would be of no interest. This is exactly the objective of the Quasiturbine detonation engine use in transportation.

The development of a detonation engine provides a mean to avoid that low-power-efficiency-penalty; maybe more environment friendly as it will require low octane additive-free gasoline or diesel fuel; maybe multi-fuel compatible, including direct hydrogen combustion; and may offer reduction in the overall propulsion system weight, size, maintenance and cost. For these reasons it could be better or competitive with hybrid car technology.


More Technical

Engine Exhaust Heat Recovery with Quasiturbines

Photo-detonation engine

Quasiturbine in transportation