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LiquidPiston has been the subject of numerous technical papers. All papers are available for download below.
Alexander Shkolnik, Nikolay Shkolnik, Mark Nickerson et al., “Compact, lightweight, high efficiency rotary engine for generator, APU, and range-extended electric vehicles,” 2018 NDIA Ground Vehicle Systems Engineering and Technology Symposium, Aug 7-9, 2018, Novi, MI
This paper will overview the HEHC thermodynamic cycle and rotary X engine, and will describe the development status of the X4, a 0.8L Compression Ignition engine, funded by the Defense Advanced Research Projects Agency (DARPA), with aggressive targets including: 30 kW power, and power to weight of 1 hp/lb Operating on the HEHC cycle, the X4 engine can potentially achieve very high brake thermal efficiency of up to 45%. The paper will also provide an overview of a second smaller X engine, the “X Mini Diesel” (XMD), a small (70cc) spark-ignited (SI) multi-fueled engine that is heavy fuel compatible.
Nickerson, M., Kopache, A., Shkolnik, A., Becker, K. et al., “Preliminary Development of a 30 kW Heavy Fueled CompressionIgnition Rotary ‘X’ Engine with Target 45% Brake Thermal Efficiency,” SAE Technical Paper 2018-01-0885, 2018, doi:10.4271/2018-01-0885.
This paper presents initial progress in the development of LiquidPiston’s ‘X4’, a 30 kW heavy-fueled rotary compression ignition engine prototype. This development is partially funded by the Defense Advanced Research Projects Agency (DARPA), with broad dual-use civilian / military applications including UAVs, generators, and for propulsion. The 30 kW size may be of significant interest in the automotive application as a range extender for Electric Vehicles. The engine has exceeded the mechanical verification target, demonstrating stable operation with in-cylinder pressures of 150 bar.
Leboeuf, M., Dufault, J., Nickerson, M., Becker, K. et al., “Performance of a Low-Blowby Sealing System for a High Efficiency Rotary Engine,” SAE Technical Paper 2018-01-0372, 2018, https://doi.org/10.4271/2018-01-0372.
The X-Engine overcomes the gas leakage issue of the Wankel engine by using two axially-loaded face seals that directly interface with three stationary radially-loaded apex seals per rotor. The direct-interfacing of the apex and face seals eliminates the need for corner seals of the typical Wankel engine, significantly reducing rotary engine blowby. This paper demonstrates the sealing performance that can be achieved by this new type of seal configuration for a rotary engine based on dynamics models and experiments.
Tiago J. Costa, et al., SAE Journal Article 2016-32-0033
This paper describes the method used for heat transfer measurement and prediction on the LiquidPiston XMv3 small rotary engine at its current state of development. A 1D engine model (GT-POWER) and a 3D CFD model (CONVERGE), were coupled together with the objective of quantifying the engine heat transfer losses inside the combustion chamber.
Daniele Littera, et al., SAE Technical Paper 2015-32-0719, 2015
This paper describes development progress of LiquidPiston’s small rotary engine, the XMv3, which operates on a Spark-Ignited (SI) variant of its patented High Efficiency Hybrid Cycle (HEHC).
Alexander Shkolnik, Daniele Littera, Mark Nickerson, and Nikolay Shkolnik et al., SAE Technical Paper 2014-32-0104, 2014, doi:10.4271/2014-32-0104.
This paper describes the initial development progress of small rotary internal combustion engines developed to operate on the High Efficiency Hybrid Cycle (HEHC). This innovative rotary engine architecture shows a potential indicated efficiency of 60% and brake efficiency of >50%. Two prototype ‘X’ rotary engines are discussed. The first engine is the larger X1 engine (70hp), which operates on the HEHC with compression-ignition (CI) of diesel fuel. A second engine, the XMv3, is a scaled down X engine (70cc / 3HP) which operates with spark-ignition (SI) of gasoline fuel.DOWNLOAD NOW
Nikolay Shkolnik, Alexander Shkolnik, LiquidPiston, Inc, SAE Technical Paper 2010-01-1110, 2010, doi:10.4271/2010-01-1110 .
Available at SAE Website
Nikolay Shkolnik, Alexander Shkolnik, LiquidPiston, Inc, SAE Technical Paper 2008-01-2448, 2008, doi:10.4271/2008-01-2448
Available at SAE Website
Nikolay Shkolnik, Alexander Shkolnik, LiquidPiston, Inc, ASME Paper No. ICEF2005-1221
Available at SAE Website