The US advanced IC engine technology developer LiquidPiston has unveiled a new multi-fuel-capable rotary combustion engine, the X2. The X2 is a 40hp rotary engine that requires no valves, cooling systems, radiators or silencers.
The X2’s design operates on LiquidPiston’s patent-pending High-Efficiency Hybrid Cycle (HEHC), a thermodynamic cycle optimised for fuel efficiency. The start-up says the HEHC cycle increases average efficiency over conventional diesel engines from less than 20% to more than 50% under typical operating modes, reducing fuel consumption as much as threefold compared with conventional diesel engines.
By combining its HEHC with a rotary engine architecture, LiquidPiston has created an engine that it says is up to ten times lighter, “whisper quiet”, and two to three times more efficient at part-load than conventional engines. Other factors advanced in its favour are as follows:
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fixed volume combustion chamber permits very high temperatures and pressures;
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theoretical thermal cycle efficiency of 74%;
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expected realised brake efficiency of 58% (peak) and 50% at partial load;
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quiet operation: engine lacks poppet valves and over-expansion minimises exhaust noise;
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power modulation by cycle skipping increases efficiency and recaptures heat;
- low heat signature from over-expansion and cycle skipping eliminates water cooling;
- low production cost – the engine has ¼ the mass and 85% fewer parts than small diesel engines;
- scalable to serve a variety of applications;
- power density of ~ 2hp/Lb.
