Pratt & Whitney Unveils Revolutionary Hydrogen Aviation Steam Hybrid Engine Concept

Pratt & Whitney has introduced details of its Hydrogen Steam-Injected, Intercooled Turbine Engine (HySIITE), a groundbreaking hybrid engine concept designed to harness hydrogen's cryogenic properties and the thermodynamic benefits of steam injection. The project, part of a two-year $3.8 million initiative funded by the U.S. Department of Energy’s ARPA-E program, promises up to 35% lower energy use compared to current state-of-the-art engines and a staggering 99.3% reduction in nitrogen oxide (NOx) emissions.

https://aviationweek.com/aerospace/emerging-technologies/pratt-whitney-unveils-details-hydrogen-steam-hybrid-engine-cycle

HySIITE: A Game-Changer in Hydrogen Aviation Propulsion

The HySIITE concept leverages a semi-closed-loop system in which steam, produced from exhaust water condensation, is reinjected into the compressor and combustor to improve efficiency and cooling. This innovative cycle generates water vapor as a byproduct, producing 1 gallon of water every 3 seconds, which can be stored for the next flight. According to Michael Winter, Chief Scientist at Pratt & Whitney parent RTX, “We blew away the metrics,” achieving remarkable efficiency while minimizing environmental impact.

The engine's design features a compact core at the rear, where air flows in reverse through a compressor, combining with steam before combustion with hydrogen. Unlike traditional turbofans, the HySIITE system integrates evaporators, condensers, and water separators, enabling efficient heat recovery and reducing emissions. Neil Terwilliger, Pratt’s technical fellow for advanced concepts, noted that steam injection allows higher operating pressure ratios and enhanced intercooling without conventional material limitations, resulting in unprecedented thermal efficiency.

Pratt & Whitney is extending its hydrogen propulsion research through initiatives such as NASA’s AACES 2050 project and collaborations with the Netherlands’ Delft University of Technology and Canada’s HyADES project.

For more information

https://www.prattwhitney.com/

(Top image: Credit — Pratt & Whitney)

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