Libralato
CleanTech research and development

“The potential for grid-connected vehicles to decimate our demand for liquid hydrocarbon fuels should be clear. Freed from the psychological barriers which hinder widespread market acceptance of pure battery electric vehicles, plug-in hybrids with an all-electric capability of just [30] kilometres would slash liquid fuel consumption, since such a high proportion of journeys undertaken are well within this range.”

"Plugged In: The End of the Oil Age” by WWF
(Dr. G. Kendall, 2008)






Technology
Home // Technology // Alternative Experimental Engines
Alternative Experimental Engines
Other experimental engines are under development. However, none of them combines all the advantages of the Libralato engine.

Liquidpiston Engine
  • Novel design with separated expansion chamber
  • Very high thermal loading on combustion chamber device which will make sealing a significant problem
  • Friction losses very high
  • Cooling of the expander may also be an issue
RAD Max
  • Novel rotary 12-vane positive displacement device that produces 48 pump actions every revolution
  • Excessive number of moving parts needed
  • Excessive number of sliding components
  • Force translation performed by sliding components
Lontra Engine
  • Novel design based on two separate cylinders with a ceramic coated conduit joining them
  • Two cylinder design is not very compact – lower power to weight ratio
  • Conduit is vulnerable to vibration and could fracture; so the design is not so appropriate for vehicle applications
  • Company targeting different markets for compressors and gensets
Astremo Engine
  • Novel opposed 2 stroke technology
  • Exceptionally higher power to weight ratio
  • Uses piezo electric direct injection
  • Requires development of new lubrication system
  • Inherent low fuel efficiency and high emissions of two stroke design compensated for by use of piezo electric direct injection, but this is a high pressure, high manufacturing tolerance, high cost, high maintenance approach. Questionable whether it will meet Euro 6 emission standards
REVETEC Engine
  • Novel 4-stroke design uses two counter rotating tri lobular cams and rollers to produce the reciprocating motion normally generated by a crankshaft and connecting rod
  • Independently verified to achieve 38.5% efficiency (BSFC 212g/kWh @ BMEP 4.5 bar, 2000 rpm, lean-air ratio 15.2: 1)
  • Claimed to be the most efficient gasoline engine in the world
  • Licensing with Chinese manufacturers being negotiated
  • Engine itself does not represent substantial size/ weight/ cost savings
Ox2 Engine
  • The Ox2 engine is a circular engine block containing 8 cylinders which exert their force on a bevel shaped cam. While a camshaft rotates on a 4-stroke engine, the entire engine block rotates on the Ox2 engine
  • Pistons are connected by rings (called "plates") that move via rollers along a fixed cam (track)
  • At higher rpm (1,000<) the centrifugal force lifting the pistons from the track increases, therefore the size and power of the engine is limited
STAR ROTOR Engine
  • The Star Rotor engine is based on a recuperated Brayton cycle gerotor, which has separate compressor and expander units. This is predicted to have exceptionally high efficiency (up to 50% at full load) because:
    • The recuperator captures thermal energy from the expander exhaust and recycles it into the engine
    • The rotors do not touch thereby reducing friction
    • Speed control is accomplished without throttling losses
    • Fuel combustion is complete thus reducing the amount of fuel required to operate
    • Spraying atomized liquid water into the compressor allows nearly isothermal compression, reducing compression work significantly
  • This engine shares many of the advantages of the Libralato engine and even possibly exceeds them through the use of a Brayton cycle approach
  • However at full load, the engine consumes 2 gallons of water for every gallon of gasoline. This extra requirement limits the application of the engine in an automotive context
Anyoon Rotary Engine
  • The Anyoon rotary engine is a novel concept with some of the advantages of the Libralato engine and the Star Rotor engine:
    • Like the Libralato engine it uses a greater expansion volume than the compression volume
    • Like the Star Rotor engine it uses injected water to cool the combustion chamber
  • Sealing is a major problem for this design and very expensive diamond like composite materials are being investigated to counter the problem
  • Stoppers held by rollers in a track of parabolic spirals, are subject to fatigue, seal wear and maintenance issues
  • Use of injected water limits the application of the engine in an automotive context
Lotus Range Extender Engine (series hybrid)
  • Three cylinder 1.2L, 56 kg gasoline engine optimized between two power generation points: 15kW @ 1,500 rpm and 35 kW @ 3,500 rpm
  • Innovative architecture comprising an aluminum monoblock, integrating the cylinder block, cylinder head and exhaust manifold in one casting
  • This engine is not powerful enough to power a mid sized vehicle at more than about 85 mph / 140 kph
  • Engine efficiency is estimated to be significantly less than the Libralato engine, in the region of 240 g/kWh
Hefley Engine
  • The Hefley engine is a variable displacement engine with opposed pistons acting on a central cam, similar to the REVETEC engine
  • The design is not space efficient
  • Potential fatigue issues on the central connecting shaft
  • The usefulness of variable displacement for different fuels is questionable
Scuderi Engine
  • The Scuderi engine is a split cycle engine which divides the four strokes of a conventional combustion cycle over two paired cylinders, with one intake/compression cylinder and one power/exhaust cylinder
  • The design is not space efficient
  • The design involves extremely high pressures which require extremely high tolerances and high manufacturing costs
GO Engine
  • The Go engine is a conventional engine which incorporates eccentric bearings with a planetary gear. This allows variable compression ratios and use of Atkinson cycle greater expansion volume compared to compression volume
  • The engine does not offer significant advantages in terms of size, weight, vibration, noise, cost etc
Moller Engine
  • The Moller engine is a Wankel type engine with improved combustion surface coating and incoming fuel-air charge cooling. This allows it to avoid the disadvantages of the oil cooling system used by Mazda
  • The Moller engine achieves a similar power to weight ratio as the Libralato engine, but is less efficient at about 255g/kWh BSFC
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