Radical Controlled Autoignition in a HCRI Hydrogen DI Four-Stroke Diesel Engine with Reduced Heat Rejection

The aim of this work is to establish a means for operating a four-stroke direct injection (DI) homogeneous-combustion radical-ignition (HCRI) engine robustly on hydrogen with low NO_x emissions. To this end the use of fuel-insertion control for the fuel entering the radical generating mini-chambers is studied in some detail. The study points to the possibility that, if the compression ratios (CR's) are kept within the normal (conventional) range for diesel operations and heat losses are reduced, over its entire operating regime the hydrogen IC engine may be made to run with only one ignition mode: namely RI (radical ignition). Details of the altered chemistry of radical ignition and OH driven radical generation are studied numerically using a newer chemical-kinetics mechanism within two separate but connected open systems representing the distinctive main-chamber and mini-chamber processes. These two open systems are continuously interacting, passing energy and chemical species between themselves and the manifold.