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LiquidPiston inverse Wankel engine tested for U.S. Army 10-kW generator prototype

This 10-kW generator prototype is powered by LiquidPiston's 25-hp heavy-fueled XTS-210 rotary engine. [Credit: Image courtesy of LiquidPiston]

 

 

 

 

LiquidPiston has begun testing its 10-kW heavy-fueled generator prototype that uses the Bloomfield, CT-based company's 25-hp heavy-fueled XTS-210 rotary engine that features an inverse Wankel design.

The company has been awarded over $65 million in Department of Defense (DoD) contracts, including an $8.3 million development contract with the U.S. Army in 2023, to develop a lightweight and ultra-portable generator for the military. The 10-kW generator prototype now being tested is meant to address DoD priorities for a smaller footprint and increased portability.

According to a LiquidPiston company brochure on the unique engine design, "The X-Engine [development platform] can be likened to an 'inverted' Wankel rotary design, having a trochoidal rotor and three-lobed housing. It leverages a stationary combustion chamber, which enables a higher compression ratio with direct injection of fuel, leading to better efficiency and optimized fuel air mixing.

The XTS-210 engine is the size of a basketball. [Credit: Image courtesy of LiquidPiston]

 

 

Additionally, "stationary apex seals reduce blow-by and offer direct lubrication, improving efficiency, emissions, and durability. The X-Engine has few moving parts and either three or six combustion events per rotor revolution, resulting in very high power density. Except for ancillary parts, there are only two primary moving parts, the shaft and the rotor, making the X-Engine simple and elegant in its implementation."

LiquidPiston X Engine. from LiquidPiston on Vimeo.

In the traditional Wankel engine design, a rounded triangular rotor spins in an eccentric orbit within an oval chamber, with each rotation producing three power strokes -- where the engine generates force. In the LiquidPiston X engine designs, an oval rotor spins within a modified, rounded triangular housing.

LiquidPiston - Intro from LiquidPiston on Vimeo.

The 25-hp XTS-210 adds up to one bar of boost through supercharging and operates as a two-stroke, producing six combustion events per revolution of the rotor, to deliver smooth power from a lightweight package, roughly the size of a basketball.

The LiquidPiston 10-kW genset is designed specifically to meet the DoD's portable electric genset specs at approximately one-quarter the size and weight of the U.S. Army's current Advanced Medium Mobile Power Source (AMMPS) 10-kW generator system.

The 10-kW system incorporates all components required for reliable and efficient power production in the field, including the XTS-210 rotary engine, a high-performance electric motor/generator, custom power electronics, controls, a thermal management system, a fuel tank, muffling, and military-grade packaging. LiquidPiston says the generator is designed in the long term to be plug-and-play compatible with today's AMMPS systems, and it will have similar connectivity and interoperability.

Being smaller and lighter than the DoD's currently deployed 5-kW and 10-kW gensets, and approximately the same size as the currently deployed 3-kW genset, LiquidPiston's 10-kW genset could greatly simplify DoD generator procurement and logistics by potentially replacing three products with a single product.

While being developed initially with an eye on military specifications, the base generator technology can be applied commercially in applications operating on heavy fuels including diesel, kerosene, and jet fuel, or it can be configured to be multi-fuel capable, compatible with gasoline and gaseous fuels such as propane.

NOTE: Please see the LiquidPiston XTS-210 brochure for more specs, including additional comparisons to Kohler KDW1003.

The 10-kW genset leverages the XTS-210 engine's patented High Efficiency Hybrid Thermodynamic Cycle™ (HEHC) design, offering several key benefits over current generator technology:

• Lightweight:Up to 75% lighter and smaller than the currently fielded AMMPS.
• Easy to transport: Can be man-portable, instead of requiring a truck, trailer, or forklift.
• Space efficient: Occupies only about 9 cu. ft of space.
• Heavy- and multi-fuel capable: Designed for jet fuel, the engines have also been operated on gasoline, diesel, propane, and hydrogen.

VIDEO: A see-through LiquidPiston rotary engine was built by Warped Perception. [Credit: Warped Perception]

According to the company, "The X-Engine technology platform is inherently scalable and has been demonstrated to date in engines from 4 to 70 hp."

Learn more at liquidpiston.com. You can also view the company brochure (PDF) on the XTS-210 engine at liquidpiston.com/xts-210-engine.

LiquidPiston's XTS-210 heavy-fueled rotary engine is the result of significant internal research and development. The XTS-210 is also being integrated into a hybrid eVTOL UAS (unmanned drone) for a U.S. Army demonstration that will occur later this year.

Sources: LiquidPiston, Warped Perception (video)

Published October 2024

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