Single-Cylinder Hydrogen, Spark Ignition Engine

Single-cylinder hydrogen research engine

Hydrogen-powered engines could act as a bridging technology toward a large-scale hydrogen infrastructure by using the well-known and widely used internal combustion engine as the device that transforms the energy stored in hydrogen into motion.

The U.S. Department of Energy has set challenging goals for hydrogen internal combustion engines:

• A brake thermal efficiency of 45%
• Tier 2 Bin 5 emissions (less than 0.07 g/mi NO_x emissions)
• Equal or better power output than a comparable gasoline engine
• A cost target of $45/kW by 2010
• A cost target of $30/kW in 2015

In order to meet these targets, Argonne is researching advanced mixture formation and combustion concepts, as well as engine internal emissions reductions measures. Research on single-cylinder hydrogen research engines focuses on advanced injector design and injection strategies to improve the efficiency of hydrogen combustion engines, while reducing emissions at the same time.

Promising operating strategies include various variants of hydrogen direct injection with custom-designed injector nozzles and advanced injection strategies with multiple injection events. Although these advanced combustion concepts can significantly reduce nitric oxide emissions (the only relevant emissions component in hydrogen combustion engines), recent activities have also focused on engine-internal emissions reduction measures like water injection.

Multi-Cylinder Hydrogen, Spark Ignition Engine

Multi-cylinder hydrogen engine

In order to determine real-world engine efficiency and emissions behavior, Argonne is testing the most promising hydrogen combustion concepts developed on the single-cylinder hydrogen engine on a multi-cylinder hydrogen engine. This 4-cylinder hydrogen engine is equipped with a supercharger and intercooler, as well as an after-market Engine Control Unit (ECU) that allows full calibration access to the engine.

Currently, this multi-cylinder engine is being operated with hydrogen port injection on a variable air/fuel ratio operating concept. At low engine loads, very lean combustion of hydrogen air mixtures allows efficient and virtually emissions-free operation. With increasing engine load demand, the amount of hydrogen is increased while keeping the amount of air constant. Using the supercharger enables a further extension of this operating regime up to engine loads equivalent to a comparable gasoline engine.

The goal of this research is to fully characterize a hydrogen engine in real-world operation. Further steps for this project include the implementation and operation of the hydrogen multi-cylinder engine on a vehicle platform under transient operating conditions. Also, more advanced hydrogen direct injection strategies will be transferred, implemented and tested on this engine platform.

May 2008