Moteur  QUASITURBINE  Engine

Mai 2002 - May 2002
Article paru dans le
“GHG Alberta Solutions Showcase Newsletter”


"Ultra-low Emissions and High Engine Efficiency Fuel Interest  
In the Combined Cycle Quasiturbine"
Gilles Saint-Hilaire (Quasiturbine Agence Inc.)
George Marchetti (Maverick Combined Cycle Engines) 
Publié par - Published by

Des copies peuvent être obtenues de
Patrick von Hauff 



Figure 1 
Caption: Basic operating mechanism of the Quasiturbine engine


Figure 2 
Caption: The combustion Quasiturbine engine


Figure 3 
Caption : Energy and power output densities of various vehicles power sources. 
Ref.: Romance of the engines, by Dr. Tukashi Suzuki, SAE Publishing. 


(Fichier texte ci-bas - Texte file below)

Ultra-low Emissions and High Engine Efficiency Fuel Interest  
In the Combined Cycle Quasiturbine
Gilles Saint-Hilaire (Quasiturbine Agence Inc.)
George Marchetti (Maverick Combined Cycle Engines)

The power generation technologies of the twenty-first century will require that four primary factors be considered in any future engine design:

Energy resource availability; 
Emissions characteristics; 
Engine efficiency; and 
Engine cogeneration potential.

With respect to energy resource availability in North America, leading energy experts, such as Robert Hefner Ref.1, have forecast that domestic natural gas supplies could meet existing energy usage patterns for the remainder of this century. Toward the end of the century, as natural gas supplies decline, a shift to hydrogen as a primary fuel may well occur.  Because of increasing concerns about the effects of global warming and acid rain on the biosphere, future power generation technologies must also have extremely low emissions signatures, particularly with respect to sulphur dioxide, oxides of nitrogen, oxides of carbon and volatile hydrocarbons.  The concerns about energy resource availability and emissions are intimately related to the third factor, which is engine efficiency.  All else being equal, less fuel is used and fewer emissions are released to the atmosphere by an engine that is more efficient in producing useful work from a given fuel input.

One of the most efficient power generating systems currently in widespread use is the combined cycle gas turbine.  Utility-grade combined cycle turbines Ref. 2 can have an electrical efficiency approaching 55%. The key to their superior efficiency is that the heat from the combustion of the fuel is used in two power generating cycles by the engine.  In the first cycle, the heat of combustion is used to turn a gas turbine generator.  In the second cycle, the exhaust heat from the gas turbine cycle is used to produce steam in order to turn a steam-powered generator.  Extremely high efficiency results because the heat of fuel combustion is used in two engine power cycles, not just one.  However, the size and complexity of utility-grade systems make them impractical for most combined heat and power (“CHP”) applications. 

A relatively new type of turbine has been developed by Quasiturbine Agence Inc. of Montréal, Canada Ref. 3, which is known as a “Quasiturbine” (“QT”).  The QT is a relatively low RPM engine.  Figure 1 illustrates the basic QT operating mechanism, which includes a rotor, stator with or without the four carriages.  The Quasiturbine concept has resulted in a large family of potential engine configurations, including combustion QT, a steam-powered QT and a Stirling QT.  Because the centre of the QT is hollow, an electric generator shaft can be inserted directly into the core of the engine. Consequently, the QT is able to directly drive conventional electric generators.

The QT has multi-fuel capabilities and can be operated in internal combustion mode with a gaseous fuel, such as natural gas, syngas or hydrogen.  The ports and spark plug of the combustion QT, as illustrated in Figure 2, can be oriented either radially or axially.  With its high pressure compression ratios, the combustion QT is capable of operating in photo-detonation mode without a spark plug.  Because the combustion QT is a high compression photo-detonation engine, the combustion of natural gas results in extremely low emissions of oxides of nitrogen and other greenhouse gases.  The QT can also function as a Stirling engine Ref. 4. A Stirling engine produces power by virtue of a working “fluid”, which may be a liquid or a gas (such as water or helium, for example) transiting between zones of high temperature and of low temperature within the engine.  The rotor of a Stirling QT engine is “pushed” by the pressure created by the heated working fluid in the high temperature zone and is “pulled” by the partial vacuum created by the cooled working fluid in the low temperature zone.

The combined cycle Quasiturbine (“CCQT”) increases engine efficiency by integrating a combustion QT with a Stirling QT.  During operation, the combustion QT produces both power (which is delivered as torque to the rotating shaft) and hot combusted exhaust gases.  In a single cycle engine, the latent energy of the hot exhaust gases is either vented to atmosphere or, in the CHP mode, is recycled for hot water or space heating.  In contrast, the Stirling QT utilizes a portion of the energy of the hot exhaust gases to generate more engine power, thereby increasing overall engine efficiency.  A thermal recycling unit delivers the hot exhaust gases to the Stirling QT's “hot temperature zones”.  As the temperature of the working fluid in the hot temperature zone increases, additional power is delivered to the shaft.  As the shaft rotates, the heated working fluid is transferred to an adjacent “cold temperature zone” and is cooled.  The fuel for the combustion QT travels through the cold temperature zone of the thermal recycling unit, cooling the working fluid. The heated fuel is then combusted in the combustion QT.  This technique is commonly known as “process fuel cooling” and may be supplemented with other standard cooling techniques.  Mechanical efficiencies of approximately 50% are anticipated with a CCQT operating on natural gas.  Like other CHP systems, the heat not used by the CCQT to generate power can be directed to hot water or space heating uses.

The CCQT is also a potential alternative to the automotive internal combustion engine.  Because operation in CHP mode is not practical for a vehicle, “on-board” engine efficiency is the primary measure of a vehicle's overall efficiency.  The Stirling QT's “on-board” engine efficiency can be substantially increased by using a very cold fuel, such as liquefied natural gas (-160C) or a refrigerated gas like natural gas or hydrogen (-50C to -75C).  The Stirling QT is unique in that it is able to recover a portion of the energy used to refrigerate or to liquefy the fuel, thereby further increasing the CCQT's “on-board” efficiency.  Because of its efficiency, a CCQT, operating on a very cold fuel, should more than double a vehicle's average miles per gallon (gasoline equivalent), while simultaneously reducing emissions of oxides of carbon, oxides of nitrogen and volatile hydrocarbons to a fraction of that produced by a gasoline engine.  With hydrogen as the fuel, the CCQT would function as a high efficiency “zero emissions” engine. Development and testing of QT prototypes are being conducted by Quasiturbine Agence Inc. under the direction of Dr. Gilles Saint-Hilaire.

1. Hefner, Robert, 27 International Journal of Hydrogen Energy 1 (2002).
2. Flavin, Christopher, Power Surge, p.101 (W.W. Norton & Company 1994).

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