LiquidPiston unveils 40-bhp X2 rotary engine with 50% thermal efficiency

Conventional internal combustion engines, using the technology that is probably in your car, have very poor efficiency. In practice, around 20%.¹ The other 80% escapes largely through the exhaust pipe & the cooling system.

A new engine combustion cycle has been developed by a startup called LiquidPiston.

Because of its improved efficiency & use of aspects of Otto, Diesel, Rankine, & Atkinson cycles, LiquidPiston calls their new combustion cycle, “High Efficiency Hybrid Cycle” (HEHC).



At first glance, the HEHC resembles the Wankel rotary. Actually, the Wankel is even less efficient than other internal combustion engines. This is due, in large part, to the long, narrow combustion chamber, which allows excessive heat energy to be lost from the burning fuel/air mixture, to the chamber walls.


Notice the long, narrow combustion chamber (red) in the Wankel, & the compact combustion chambers (black) in the LPI X1.
Credit: LiquidPiston/Popular Mechanics

HEHC has a high compression ratio (18:1) & contains the combustion process in a smaller space than any other internal combustion cycle technology. This increases speed of combustion & minimises loss of heat energy. Finally, HEHC lengthens the expansion part of the cycle, so that the exhaust gasses are released at close to atmospheric pressure, thereby transferring the maximum possible fraction of the energy released by combustion to the piston, & reducing exhaust noise. Because so much of the heat energy released by the burning fuel is converted to mechanical energy, less is lost as heat, so that liquid cooling is not required.

Other advantages include small size & weight, compared to other types of internal combustion engines.

http://www.gizmag.com/liquidpistol-rotary/24623/

http://www.popularmechanics.com/cars/a8174/liquidpistons-hyper-efficient-engine-turning-the-rotary-inside-out-13817971/

https://newsoffice.mit.edu/2014/liquidpiston-small-efficient-rotary-engine-1205
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¹ Wikepedia: "Fuel efficiency", https://en.wikipedia.org/wiki/Fuel_efficiency / Hyper-Efficient Engine: Turning the Rotary Inside Out internal combustion engine startup LiquidPiston leap in efficiency from 20 percent to 50 percent automakers reciprocating piston engine hybrid systems improved accessories independent inventors huge improvements basic efficiency internal combustion engine engineering Bloomfield Connecticut LiquidPiston X1 engine just three moving parts major components raise thermal efficiency gas engine reduction weight size wasting much less energy combustion cycle 80 percent energy fossil fuels heat pressure exhaust dumped atmosphere radiator LiquidPiston's design capture waste higher efficiency Alec Shkolnik President CEO LiquidPiston thermal cycles design theoretically capable of 75 percent thermal efficiency 57 percent real world applications Wankel rotary seals Wankel housing X1 engine reduction oil consumption rotary engine enhancements direct injection high compression ratio 18:1 change geometry combustion chamber constant volume ignition air-fuel mixture auto-ignites like a diesel burned much longer than normal more complete combustion low emissions very high chamber pressures high pressure nearly atmospheric pressures available energy is extracted exhaust physically pushed out internal combustion engine releases very energetic high-pressure exhaust gas convert more heat energy mechanical force less heat has to be removed block no water cooling system engine under load cool down skip fuel injection event suck in cool air heated by the block exhausted inject water into the combustion chamber three effects cooling the engine reduced reducing NOx emissions converting water to steam increases power compact design LiquidPiston's lab engine 80 lbs 40-hp model weigh less than 50 lbs in production 40-hp diesel LiquidPiston hybrid range-extenders military applications boat engines license intellectual property manufacturing petrol gasoline engine /