Homogeneous Charge Catalytic Ignition of Ethanol-Water/Air Mixtures in a Reciprocating Engine

Lean ethanol-water/air mixtures have potential for reducing NOx and CO emissions in internal combustion engines, with little well-to-wheels CO2 emissions. Conventional ignition systems have been unsuccessful at igniting such mixtures. An alternative catalytic ignition source is being developed to aid in the combustion of aqueous ethanol. The operating principle is homogeneous charge compression ignition inside a catalytic pre-chamber, which causes torch ignition and flame propagation in the combustion chamber. Ignition timing can be adjusted by changing the length of the catalytic core element, the length of the pre-chamber, the diameter of the pre-chamber, and the electrical power supplied to the catalytic core element. To study engine operation, a 1.0L 3-cylinder Yanmar diesel engine was converted for ethanol-water use, and compared with an unmodified engine. Comparing the converted Yanmar to the stock engine shows an increase in torque and power, with improvements in CO and NOx emissions. Hydrocarbon emissions from the converted engine increased significantly, but are largely due to piston geometry not well suited for homogeneous charge combustion. No exhaust after treatment was performed on either engine configuration. Applying this technology in an engine with a combustion chamber and piston design suited for homogeneous mixtures has the potential to lower emissions to current standards, with a simple reduction catalytic converter.