Quasiturbine> Advantages> Efficiency


Application advantages could be as precious as intrinsic engine ones.
Engine efficient is just the beginning of a saving cascade.
Quasiturbine offers optimum efficiency with a variety of fuels and modes.

Quasiturbine Efficiency

About QT Efficiency - See Also:

Specific efficiency are presented on corresponding
engine / expander description page.

Internal combustion is completed by a presentation at

Gas expander theory and efficiency is covered at

Where is the Energy Wasted?

Engines do not create energy, they only transform it into mechanical energy with some inevitable losses. Physics imposes thermodynamic losses to energy transformation which cannot be circumvent, but engine losses are more important than the minimum the physics is telling us...

In internal combustion engine, the energy is lost in several ways. Vacuum intake of the gas engine is responsible for about half of the gas consumption in today vehicle (hybrid concepts are trying to harvest some of that, while detonation engine could eliminate this loss). Inhomogeneous diesel fuel mixture is catastrophic to combustion. Partial combustion in gas engine is also a lost. Internal engine accessories like cam shaft and valve train are reducing the net available engine power. Thermodynamic imperfect machine cycle is also a substantial lost. Lubrication friction is taking an other 3%. Scaling down engine is not helping either...

Large utility plants convert energy more efficiently than small distributed units and should be favored when possible. The detonation Quasiturbine engine is one of the very few long term means to match utility efficiency the distributed way, while being as chemistry clean as possible.

Internal combustion residual pressure:
Once the piston get to BDC, it cannot extract any further pressure energy. However, the combustion gas pressure is still present and flushed out. At that time, back pressure has not negative effect on the piston while in BDC. This is the residual combustion pressure the turbo (or pressure exhaust QT) is designed to recover, and fortunately, higher is the initial piston mixture pressure (higher engine power), higher is this residual gas combustion pressure. Same happened within IC Quasiturbine.

Engine Exhaust Heat Recovery:
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. Stirling and short steam circuit Quasiturbine could do similarly!

Relative to the pressure flow energy conversion role of the Quasiturbine, the efficiency (not an absolute efficiency) is given by the (power or torque obtained) divided by the (power or torque which could be obtained according to formula), which is typically between in the 80 % efficiency as of 2009.

A Cascade of Savings

Engine efficiency is a large domain of activity which extends far behind 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! This is one of the paradox of today hybrid vehicle concept: 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?

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.

However, 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 are needed with corresponding efficiency increase.
  • Because the Quasiturbine can be 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.


Such small and efficient Quasiturbine steam engine makes mobility possible.

Thermal solar steam could drive a Quasiturbine. Solar concentrator could directly heat up a Quasiturbine engine bloc, which would act as evaporator, super-heater and motor! It could also be used for small geothermal or industrial heat process.

At home, combine electricity and heating would be possible from several sources, sometimes with complementary higher temperature source.

Quasiturbine Stirling could be made cylindrical and be inserted directly into the chimney for optimum heat recovery.

Engine Exhaust Heat Recovery:
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. Stirling and short steam circuit Quasiturbine could do similarly! Same technology could apply to:
Industrial exhaust gases heat recovery
industrial furnace heat recovery
Industrial process heat recovery
Chimney or stack heat recovery
Waste heat recovery
Solar heat recovery
Geothermal heat recovery
Thermal nuclear heat

ORC (Organic Rankine Cycle)

Engine suitable for ORC (Organic Rankine Cycle) in Solar, Geothermal and Waste Heat Recovery.

Efficient at All Loads

The benefit of power modulation is precious. Pneumatic, steam or combustion turbine engines all have one major limitation: Their efficiency depends of the load, the rpm, the power... They have to be operated at their design condition to meet their optimum efficiency at a given working power. Because the Quasiturbine is not an aero- or hydro- dynamic engine, but a static pressure type of engine, it has an optimum efficiency on a large range of power, load and rpm. This allows for efficient uses in power modulation applications with optimum energy saving and efficiency. The Quasiturbine is consequently a superior gas expander and most suitable for efficiency difficult steam co-generation projects.

Piston Beau de Rocha (Otto) gas engine and the diesel engine have similar optimum power regime limitation. Only the detonation engine has not.

Quasiturbine as an Immediate Solution

Engines are at the end of the energy chain and they affect the most the energy users. More efficient engines not only save fuel, but any bit of saving has direct amplified impacts on all anterior stages of the energy cascade and industry.

Click here for a 2000 pixels high resolution image

The Quasiturbine in Beau de Rocha (Otto) cycle is a relatively simple technology which could be widely used within a few years with substantial efficiency benefits over the piston engines in many applications. Other claimed advantages include high torque at low rpm, combustion of hydrogen and compatibility with detonation mode.

A lot of research are going on to increase the efficiency on the long term with piston, hydrogen, fuel cell... Hybrid concepts are ways to harvest part of the "low power efficiency penalty" of the piston engine used in vehicle, but counter-productive measures limit the long term perspective until they could efficiently fuel from the electrical grid. None of these solutions are short term stable and competitive.

By opposition to dozens of new engine designs, the most important at this time about the Quasiturbine is not the actual machine, but the fact that it does unknot a new field of development and offers means to achieve what no other engine design has suggested or is able to, and specially for detonation where piston engine has failed for over 40 years...

Efficiency as Rotary Expander

Gas Pipeline Pressure Energy Recovery - Rotary Pressure Expander
What about an "energy recovery rotary pressure regulator" ? An interesting application of the pneumatic Quasiturbine is to recover the pipeline high pressure energy at local distribution stations. Instead of using a conventional pressure regulator (an energy dissipative device), a pneumatic Quasiturbine will rotate under the pressure differential and the flow will be controlled by the rpm, i.e. the torque applied on the Quasiturbine shaft. It does act as a dynamic active rotary valve. This way, the Quasiturbine can transform the pressure differential into useful mechanical work to run pump, compressor, ventilator, electricity generator or locally convert the energy in high grade heat (better than pre-heating the gas before that same "rotary expander", to avoid any residual condensation as done with conventional regulators). Substantial heat is now given to conventional expansion valve in pure lost, while heat given to the gas at the intake of a rotary expander is essentially all recovered in mechanical energy or electricity. Because conventional turbines can not be widely modulated in rpm and load, they are not suitable for gas flow and pressure control, while the Quasiturbine is essentially a closed valve at zero rpm, and has high efficiency at all torque and all flow rpm. With such a system, any heat added before the Quasiturbine expands the gas and increases the available volumetric flow with the result that this heat is converted in mechanical energy with a very high efficiency. All experimental demonstration has to be done only by gas experts and under all current rules and regulations. Ignoring gas expansion and considering only the gas pressure flow, a 36 inches diam. gas pipeline at 700 psi carry typically a pressure power in excess of 30 MW - 25 millions of pound-ft/sec - of zero pollution pure mechanical energy almost totally recoverable through Quasiturbines in the heart of cities and industrial parks. This is tens of giant windmills on kW-h basis!. A survey (M. Dehli, GWF Gas-Erdgas 137/4, p.196, 1996) showed that in Germany alone, the potential for utilizing this pressure in 1996 was 200-700 MW, and the gas consumption has increased since then... See the conceptual diagram and a pipeline technical paper.

Economics: Take any similar fossil fuel electric generation station, and set the fuel cost to zero, as the pressure energy recovery does not consume any fuel. It is even better than renewable, it is free energy, until the utilities start to charge for it, and make an easy extra income!

Refrigeration: Conventional pressure regulators make all the gas to expand from the constant high pressure side, and the gas pressure-kinetic energy at the needle is converted into undesirable heat, reducing accordingly the amount of cold produced. The Quasiturbine rotary expander allow for individual chamber to expand at a variable reduced pressure during expansion, and such reduces the gas kinetic energy transformation into destructive heat. Furthermore, the Quasiturbine recuperates mechanically the gas differential pressure energy, which can be used to run more compressors and make more cold... A double energy efficiency gains! A single Quasiturbine in tubo-pump (tubo-compressor) mode could have one circuit used as rotary expander while the other is used to compress back some of the expanded gas. This offers great enhancement of thermodynamic cooling machine, and specially in high power LNG - Liquid Natural Gas liquefaction stations. Of course, this efficiency enhancement is also available for more modest cooling system and air conditioning equipments. With Quasiturbine rotary expander, the efficiency of a gaseous only (like dry air) system reaches almost the efficiency of a phase change liquid-gaseous system, and sophisticated phase change chemical products often environmentally unwelcome are not anymore needed.

More Technical


Quasiturbine Rotary Expander

Intake cut off valve