Quasiturbine tech promises engine paradigm shift
By Gizmag Team
November 26, 2004
November 27, 2004 A white paper on a revolutionary new approach to engine design has been released at the Global Powertrain Conference (GPC) in Dearborn, Michigan, USA. Quasiturbine technology uses photo-detonation for low-power-efficiency and requires low octane, additive-free gasoline or diesel fuel. It is also multi-fuel compatible (including direct hydrogen combustion) and offers a drastic reduction in existing propulsion system weight, size, maintenance and costs. Utilised within the internal combustion engine, the photo-detonation process could save half the gasoline now consumed by vehicles and provide substantial environmental benefits.
The Quasiturbine looks at first like a rotary engine with a deformable rotor made of four identical blades, but because it has no crankshaft and does not follow sinusoidal motion, it has properties far different from the piston and the Wankel rotary piston engine. The Quasiturbine engine has been developed to simultaneously optimise the 14 most important engine parameters, including compatibility with the revolutionary photo-detonation mode (knocking), which the piston engine cannot effectively tolerate. When taken together, these improvements increase fuel efficiency while simultaneously reducing exhaust emissions.
Inspired by the turbine, it perfects the piston, and improves on the Wankel.
The Quasiturbine is a continuous flow engine at intake and exhaust. An engine's piston completes 4 strokes in two rotations, the Quasiturbine completes 32. Because it was conceived for thermal and photonic ignition, the Quasiturbine cannot be considered as a "rotary piston engine", nor be correctly characterised by the piston paradigms. Note however, that the Quasiturbine can be operated at a lower compression ratio in standard Otto and Diesel cycle modes, with substantial benefits as well. The combustion Quasiturbine is therefore a combination of the best elements of other internal combustion engines, as defined by the following:
- Quasiturbine photo-detonation of the homogenous fuel/air charge eliminates the electronic ignition requirement for most fuel.
- Electronic ignition in the piston gasoline engine is required because of intake vacuum and incompatible long duration compression "pulse structure" limitations in the cylinder.
- Photo-detonation completely combusts the fuel in the fuel/air charge because of the short, but powerful, pressure pulse and because of the fast nearly linear variation of the Quasiturbine's maximum pressure zone, which rapidly closes and re-opens the combustion chamber. The diesel engine can only incompletely combust the inhomogeneous fuel injected into the heated, compressed air in the cylinder. The Quasiturbine (unlike the diesel) is therefore a "clean homogeneous combustion" engine. It has virtually no emissions other than the standard products of combustion, e.g., CO2 and H2O. "Clean combustion" also implies that the Quasiturbine engine is more fuel-efficient than the diesel.
- Photo-detonation in the Quasiturbine occurs rapidly at top dead centre. In the diesel engine, ignition of the injected fuel occurs somewhat after top dead centre, usually about 12 degrees or so, is progressive with time and which contributes mechanically to protect the piston. The Quasiturbine's power stroke is somewhat longer "with early and late mechanical energy conversion" and the exhaust somewhat cooler, which also implies a more efficient engine.
- Because the temperature of stator/rotor is not significant in the photo-detonation process (light ignition) and because the shorter Quasiturbine pressure pulse is self-timing, premature ignition is not a concern. The combustion Quasiturbine can have a very simple cooling mechanism, such as air-cooling, mainly when operating on a high volatility, low specific energy fuel like natural gas.
- The Quasiturbine is suitable for multi -fuel use, including hydrogen combustion. It can also be operated in a combined thermal cycle mode (including steam and Stirling mode hook-up on the same shaft) thereby further increasing the efficiency.
- Finally, the Quasiturbine can operate in the more conventional Otto or Diesel mode, yet retains its added value characteristics when compared to the piston engine.
The principal difference between the Otto and the photo-detonation Quasiturbine is the mechanism of fuel ingestion, ignition and combustion. The Otto mode Quasiturbine uses a spark ignition, while the photo-detonation Quasiturbine eliminates the need for spark plugs and an electrical ignition system. In photo-detonation mode, the fuel/air charge auto-ignites with a short, powerful pressure pulse in the Quasiturbine's combustion chamber. With the exception of the method of fuel ignition and combustion, and lean fuel condition, the operational characteristics of the Quasiturbine engines in both modes are essentially the same from the user perspective.
For the Otto piston engine, about half the gasoline used in the transportation sector is literally wasted to fight the atmospheric intake vacuum depression generated by the carburettor butterfly-valve (the engine-braking effect). This is also responsible for nearly half the pollution generated by gasoline transportation activities.
The Quasiturbine offers the potential for significant increases in fuel efficiency due to several factors, including virtually complete combustion of the fuel/air charge, high compression ratios, early and late mechanical conversion and the absence of peripheral accessories like camshaft. In fact, cost reduction is so important in transportation that even if Quasiturbine had a significantly higher cost (which is not the case), the fuel saving over the life of the vehicle would make the Quasiturbine engine a "no-charge" feature. This would be true even in non-photo-detonation Otto mode. Accelerated reduction in combustion chamber temperature, pressure and confinement time also leads to less heat transfer toward the engine block, further contributing to efficiency improvements over the piston engine.
Regardless of the method of ignition and combustion, the Quasiturbine is a uniquely "clean combustion" engine. The pollution-related products of commercially available internal combustion engines include carbon monoxide, other un-combusted hydrocarbons and oxides of nitrogen. Carbon monoxide and un-combusted hydrocarbons are the result of incomplete combustion of the fuel in the engine. The Quasiturbine's unique engine architecture minimizes the formation of these pollution-related engine products. Consequently, the chemical reaction that leads to the formation of oxides of nitrogen is retarded or prevented.
Quasiturbine and The Hydrogen economy
A 2003 report from the Massachusetts Institute of Technology (MIT) reached the following conclusion: "Improving gasoline and diesel engine is the way to go. The Hydrogen car is no environmental panacea: The hydrogen fuel cell will not be better in terms of total energy use and greenhouse gas emissions by 2020". With photo-detonation, however, the internal combustion engine can be transformed into a near-term environmental solution.
So far, carmakers like GM have invested heavily in developing fuel cells to power electric motors in vehicles, while others like BMW have studied the burning of hydrogen in internal combustion engines. Excluding a nuclear source, hydrogen must be processed from some other fuel source, such as natural gas, with a corresponding loss of about 30% of the energy value of the fuel during processing. When the energy loss associated with processing is taken into account fuel cells will only be about 35% fuel-efficient or so at most. In addition, because fuel cells are generally dependent on hydrogen, there are serious issues about production, transmission and storage of hydrogen fuel that must be addressed before hydrogen fuel cells can become a generally available option.
An extensive study commissioned by the U.S. Department of Energy released in 2002, in conjunction with announcement of the "FreedomCAR" initiative, outlines the extraordinary complexity and cost of this undertaking.
While hydrogen is the "Achilles heel" of fuel cells, the Quasiturbine has no such limitations. It is a multi-fuel engine and can use existing fuels and infrastructure (and even hydrogen, if and when, available).
For more information see: http://quasiturbine.com/