|The 11-liter City Engine for HCNG
City Engines is undertaking an 18-month low-emissions bus program to be funded jointly by the Los Angeles County Metropolitan Transit Authority (LACMTA) and California’s South Coast Air Quality Management District (SCAQMD). The LACMTA is the largest single operator of natural gas fueled transit buses in the United States.
The program will include the re-powering and evaluation of four transit buses, two running on Compressed Natural Gas (CNG) and two running on a 30% Hydrogen, 70% Natural Gas (HCNG) blend. All four engines will employ the very low emissions lean burn HCNG and CNG technologies developed and patented by Collier Technologies Inc. over the past 13 years. City Engines is the exclusive licensee of those Collier technologies.
Hydrogen-CNG volumetric mixtures of 20% or less hydrogen are called Hythane; mixtures above 21% are patented and held by Collier Technologies, which has licensed it to City Engines. With a properly tuned and configured engine, vehicles can increase thermal efficiency while achieving extremely low emissions.
|NOx vs torque for a 30% HCNG City Engine compared to an 8.1-liter John Deere engine.
The hydrogen in HCNG is a flame enhancer that promotes combustion with a large amount of charge dilution (lean burn or EGR). HCNG engines operate in lower-combustion temperature regimes that produce very low NOx.
The new 30% HCNG 11-liter City Engine to be employed is based on a proven Doosan Infracore (Korea) short block engine design, with newly redesigned Collier/City Engines cylinder heads that support quiescent combustion and increased air flow. (Earlier post.)
The new engine configuration was demonstrated on a dynamometer in 2005, and proved its ability to more than meet the upcoming 2007 California CARB/EPA heavy-duty emissions standard. The direct drive engine produced NOx emissions of 0.1 g/hp-hr across the engine’s entire operating range. The upcoming 2007 Standard calls for 0.2 g/hp-hr of NOx. The emissions results were obtained at the exhaust, without the use or need of a three-way exhaust catalyst.
Part of the project will be certification of the engines to both existing and upcoming CARB/EPA emissions standards.
Subcontractors to City Engines will be Trillium USA, LLC, who will provide the HCNG fueling infrastructure for the demonstration; and Valley Power Systems Inc., who will provide installation and testing support, as well as future regional distribution services.
City Engines is also developing 8-liter and 5.9-liter HCNG engines.
City Engines: HCNG Is the Path to the Hydrogen Economy